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2025-10-19 01:29:01
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https://www.eevblog.com/forum/beginners/10-mhz-reference-signal-connection-at-spectrum-analyzer-and-signal-generator/
|
10 MHz reference signal connections for spectrum analyzer and signal generator ? - Page 1
|
[
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 12, 2019, 08:15:01 am",
"content": "My spectrum analyzer (SA) and my signal generator each has an input for external 10MHz reference signal, and also I have 10MHz from GPSDO.As my SA does not have the internal tracking generator, I will use the external sig-gen.All I want is to do is a simple sweep measurement on DUT across the defined frequency range.How to connect the 10MHz signal source, topology wise, to these two equipments SA and sig-gen ?FYI, the SA has only single port which can be configured either IN or OUT for the 10MHz signal, while the sig-gen has two separated ports, IN and OUT.TIA"
},
{
"post_id": "",
"author": "capt bullshot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 12, 2019, 09:49:52 am",
"content": "You've just suggested the solution:If your GPSDO has only one output, connect this to Sig Gen ref input, Sig Gen ref output to SA ref input.Otherwise, of one can (or has), one uses an distribution amplifier for the 10MHz ref.Edit: for your purpose, most probably you won't need that external reference at all. Let the Sig Gen and the SA run on their internal refs."
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 12, 2019, 11:02:32 am",
"content": "other than that, a 50 ohm 2-way splitter maybe with equal cable length if synch is required, ymmv."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 12, 2019, 07:07:23 pm",
"content": "It should not matter how you hook them up as long as the signal levels are appropriate. Through the signal generator is probably the easiest since it only requires two cables."
},
{
"post_id": "",
"author": "0culus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 12, 2019, 09:17:33 pm",
"content": "I guess you might want to also verify that an external reference onto your sig gen also goes out. I would think it should, though, so you can daisy chain."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 12, 2019, 09:42:12 pm",
"content": "Quote from: capt bullshot on April 12, 2019, 09:49:52 amRight. Described measurement do not need *any* frequency accuracy from signal generator. If you trust your SA indication during other measurements, this one is no different, does not require ext.ref."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 13, 2019, 03:54:19 am",
"content": "Thanks for all replies, really appreciate it.All noted, my acquired used SA is pretty aged, it seems like the internal xtal is aged and drifted, hence the GPSDO from the 1st place. Also the sig-gen is the new member in my T&M family.All worked and done, daisy chained from GPSDO -> sig-gen -> SA, and the marker is now spot on.I guess the best is to get a 10 MHz distributor isn't it ? Here we go, another TEA adventure begins.Thanks again."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 13, 2019, 04:20:28 am",
"content": "Quote from: BravoV on April 13, 2019, 03:54:19 amThat would eliminate any issue with having the connections for daisy chaining.If you can find an analogue video distribution box with at least 10MHz bandwidth, that should work."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 13, 2019, 04:27:52 am",
"content": "Quote from: Brumby on April 13, 2019, 04:20:28 amWhat potential issue/s, if the ref signal is daisy chained ?Quote from: Brumby on April 13, 2019, 04:20:28 amYeah, currently in the process looking for it, and also I'm currently considering an offer locally here of an alternative that is an alien unknown GPSDO box that has built-in distributor, worst case if the GPSDO is unworkable (no documentation what so ever on the net), at least I can salvage the distributor part + a nice box + PSU. I've searched and asked around, seems like no one knows it, even the god of GPSDO boards, author of LadyHeather.Few shots of the thingy from the seller."
},
{
"post_id": "",
"author": "0culus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2019, 05:03:00 am",
"content": "Unless the intermediate members of the daisy chain are also amplifying the external ref signal on it's way out, you'll likely experience losses by the end of the daisy chain."
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2019, 09:47:01 am",
"content": "Quote from: BravoV on April 13, 2019, 03:54:19 amat 10MHz its easy to diy. active distributor will need 2 or few cheap gain opamps, the passive one is the said 2-way splitter earlier...https://support.channelmaster.com/hc/en-us/articles/200383715-How-Much-Signal-Do-I-Lose-Going-Through-A-Splitter-CM-3212HD-CM-3213HD-"
},
{
"post_id": "",
"author": "Shock",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2019, 11:14:05 am",
"content": "One thread on DIY distribution amps here.https://www.eevblog.com/forum/testgear/diy-10-mhz-distribution-amplifier-requirements-gathering/If you are going for an Extron the ADA 6 300MX HV is the high bandwidth model, it has several channels to distribute 10MHz, 1pps, TTL etc and 6 outputs on each means you aren't likely to run out."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 13, 2019, 12:11:47 pm",
"content": "Quote from: BravoV on April 13, 2019, 04:27:52 amFor example: 3 units with a 10MHz input and only one has a 10MHz output."
},
{
"post_id": "",
"author": "Shock",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2019, 02:35:00 pm",
"content": "Quote from: BravoV on April 13, 2019, 04:27:52 amAny deterioration in a daisy chained signal would have a cumulative effect. Noise, attenuation, effects of each instrument down the line. All things being equal, if you have a distribution amp with six outputs you get six \"identical\" signals."
}
] |
2025-10-17T18:12:47.110751
| 14
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10-turn-potentiometer-question/
|
10 turn potentiometer question. - Page 1
|
[
{
"post_id": "",
"author": "davelectronic",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 30, 2019, 04:06:47 am",
"content": "A while ago i picked up an TLC3780 step up step down converter, with the intention of putting a cheap variable bench power supply together. I've removed the pcb 10 turn voltage potentiometer, and the 10 turn current potentiometer. That went fine after wicking away the solder for clean holes for wires to panel mount 10 turn potentiometers.After measuring both potentiometers, the voltage potentiometer is 500k and the current potentiometer is 200k. Firstly i would like to keep the precision of 10 turn potentiometers, but panel mount components.But I'm finding here in the UK there are none available at those values. The project is the one that Great Scott has done on YouTube. He's potentiometers are from Europe and the US going by his list of parts availability. So two questions really, firstly could i use a lower value for these 10 turn potentiometers, or is that idea not feasible ? And if that's not possible, is there supplier of 10 turn potentiometers here in the UK where i am ? I've tried ESR electronics one of my go to components sellers. Also RS here in the UK, and ebay os a non starter, most 10 turn potentiometers on there are not much above 10K.Thanks for reading, any help appreciated."
},
{
"post_id": "",
"author": "andy3055",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2019, 04:44:37 am",
"content": "100k:https://www.amazon.com/s?k=100k+multi+turn+potentiometer&ref=nb_sb_noss500k:https://www.amazon.com/Multi-turn-Trimmable-Trimmer-potentiometer-handle/dp/B01G2Z9IAE/ref=sr_1_2?keywords=500k+multi+turn+potentiometer&qid=1572410421&sr=8-2"
},
{
"post_id": "",
"author": "MosherIV",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2019, 07:46:31 am",
"content": "https://cpc.farnell.com/search?st=10%20turn%20potentiometerI have used CPC in UK many times, without problems.I am surprised you cannot get multi turn potentiometers from RS. Normally, you are overwelmed with choice.Just checked, and yes - 219 parts to choose fromhttps://uk.rs-online.com/web/c/passive-components/variable-resistors/potentiometers/?applied-dimensions=4294873067Edit:Can you use lower values?Depends on the circuit. If the pot is just being used to generate a voltage - yes.If the pot resistance is used in circuit, then no, not without modifying the design.Yes, I see what you mean about the 500K"
},
{
"post_id": "",
"author": "davelectronic",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 30, 2019, 03:50:41 pm",
"content": "Thank you for the replys, first links are US i think, so no idea of delivering and import charges. Other following links, none of these go over 100k, so the 200k and 500k are not stocked. Just another thought, if the closest value i can find is say 50k to 100k, can i increase the potentiometers value with another 1% fixed value resistor in series with the potentiometer ? Just a thought. Although i don't know how the potentiometers value and travel and value would play out.Thank you again for your help."
},
{
"post_id": "",
"author": "SteveSi",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "December 08, 2019, 10:41:05 am",
"content": "I had the same issue when trying to remove and extend 200K and 500K pots on a power module.These points may be of use to you:1. Some (cheap?) wirewound multi-turn pots have 'no contact' spots - this obviously affects the voltage\\current on your output and can be disasterous!2. Add another 10K/20K pot for a fine voltage control - the voltage adjust pot is 500K and the centre wiper is connected the pot end terminal so it is easy to add another small pot in series - just be careful not to exceed the total resistance of 500K. Only 2 wires are neeed to connect these two (coarse+fine) pots.3. 200K and 500K are high impedance. In my power module, the 200K CC pot is actually in series with a 1.6M resistor on the PCB - so it isveryhigh impedance. Extending the connections to both pots using long unshielded wires is a bad idea! I found that just by putting my hand near the unshielded wires to the front panel pots caused the PSU module to pick up noise and increased it's total current consumption to 1A! Touching any of the pot wires insulation caused even more issues. I used shielded cable (old USB cable) and connected the braid to 0V at the PSU end, and to the pot enclosure at the other end (check for shorts). This cured most of the problems. Just be careful before putting it into a (metal grounded) case not to touch any of the pot wires.4. For the current CC pot, use a normal pot but fit a large knob for better control.I can't give you exact values because my unit stopped working after playing with it a while. I ordered a replacement but when it came, it only went up to 28V instead of 30V (the 20-turn pots were actually 460K and not 500k!). I was so disgusted that I returned the module. I came to the conclusion that this 'BOOST\\BUCK – ‘DC5-32V LTC3780 Automatic Lifting Pressure Power Step Up/Down Constant Voltage’ [Out: 80W 1-30V] was not suitable for an adjustable bench power supply as it was just too unstable.I am investigating other boost\\buck modules and combinations, but so far have not found anything which actually works without going unstable or generating voltage spikes on power up\\down, etc.See also my blog -http://rmprepusb.blogspot.com/2019/11/is-d3806-boostbuck-dc-dc-power-supply.htmlI am coming to the conclusion that a DPH3205 modulehttps://www.banggood.com/custlink/GmGKsh7ggMmight be worth the extra expense after all (if you want to use with an ATX PSU)."
},
{
"post_id": "",
"author": "t1d",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 09, 2019, 04:05:33 pm",
"content": "Quote from: SteveSi on December 08, 2019, 10:41:05 amAs this is in the beginner section, I will point out that you may want to investigate the difference between Linear and Switch-Mode power supplies and when it is appropriate to use each. My general short-take on it is this... You can use a linear supply for all applications, including those where switch-mode might be allowable, but, you must use a linear supply, when a switch-mode is not allowable. For a beginner's first bench power supply, I think it is a better investment to obtain a Linear power supply. This all pertaining to DC supplies, of course. Just saying...As for substituting a lower resistance pot and an additional resistor for a single pot, you will loose part of the operational adjustment, and therefore the range, of the circuit. I think the deficiency would be rather proportional... Let's say you use a 400 ohm pot and a 100 ohm resistor, for the 500 ohm pot. Seems to me that you would loose about 20% of the adjustment range, at the lower end, or the upper end, of the adjustment scale, depending on how the circuit is designed. PS, I did not investigate your circuit."
},
{
"post_id": "",
"author": "SteveSi",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "December 09, 2019, 04:15:41 pm",
"content": "no - as I explained, the voltage 500K 20-turn pot is wired as a simple variable resistor (one end is shorted to the wiper)so it is fine to wire in another smaller pot wired in the same way.pin 1 is connected to pin 2 (wiper)wires go to pins 1&2 and another to pin 3i.e. simple series resistor.For the CC pot however, it is not wired in this way and so it is a lot more difficult to add a fine pot.P.S. re the DPH3205 I meant that it would be best if you have to use an ATX PSU as a power source. I agree that a linear PSU is the best option for a reliable bench supply."
},
{
"post_id": "",
"author": "andy3055",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 09, 2019, 05:05:24 pm",
"content": "If you have to use a series resistor, split the value in 2 and use on either side of the pot so that your adjustment range is in the middle rather than to 1 side."
},
{
"post_id": "",
"author": "tunk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 09, 2019, 05:49:05 pm",
"content": "I don't really know much about this, but you might be able to uselower resistance potentiometers if you replace some resistors onthe board. This may be some help:https://wiki.beyondlogic.org/index.php?title=WD2002SJ_LTC3780_Synchronous_Buck_Boost_Converter_Ebay_Automatic_lifting_pressureIf I understand the schematic correctly, you could replace R9 witha 2.8k resistor and use a 100k potentiometer. Then again, this mayblow up your board."
}
] |
2025-10-17T17:59:15.974266
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10-watt-transistors-for-16-h-bridges/
|
10 watt transistors for 16 h-bridges - Page 1
|
[
{
"post_id": "",
"author": "Capernicus",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "December 27, 2021, 07:40:32 pm",
"content": "I looked at mouser, and the prices of the transistors were humungous.https://au.mouser.com/c/semiconductors/discrete-semiconductors/transistors/rf-transistors/?output%20power=10%20Wits 34 dollars for a mosfet there, but I'd prefer a BPJT.If I bought those mosfets - my h-bridges would cost $2000. that is complete rubbish. I can buy a decent computer for that much.Is there anywhere you can go for something cheaper than this!??!?"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 27, 2021, 07:48:56 pm",
"content": "Should we create a \"Capernicus just does not make sense\" thread?"
},
{
"post_id": "",
"author": "Capernicus",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "December 27, 2021, 07:50:10 pm",
"content": "Im not very good at shopping, wherever I go its always super expensive, and I know you guys know how to buy components better than me.Can you please humour my deficiencies and just help a little guy out?"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 27, 2021, 07:54:07 pm",
"content": "But seriously, what H bridge? With parts meant to be used with something like radars?"
},
{
"post_id": "",
"author": "Capernicus",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "December 27, 2021, 07:58:56 pm",
"content": "similar to this, except im doing it slightly different. u just have block both sides of the motor, its pretty simple."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 27, 2021, 08:01:34 pm",
"content": "You don't go shopping for RF power transistors to drive a motor. But use something like thishttps://au.mouser.com/ProductDetail/Toshiba/TK40A06N1S4X?qs=HVbQlW5zcXXetBqR1xf7fw%3D%3DOf course the most suitable part should be selected according to voltage and motor power which were not mentioned."
},
{
"post_id": "",
"author": "Capernicus",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "December 27, 2021, 08:07:18 pm",
"content": "THANKYOU!!! =)"
},
{
"post_id": "",
"author": "NorthernWing",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "December 28, 2021, 01:10:01 pm",
"content": "...yeah, you've been looking at RF power transistors. It sounds like you're trying to run a motor here, not a radar front end.I for one am a fan of just using these things whenever I need to drive something. They're easy to use and quite hard to kill.https://www.mouser.com/ProductDetail/Toshiba/TB67H303HG?qs=Zwj7mHVHPHQhWEhFr6x4Bw%3D%3DIf you want NPN BJTs - D44H8/D44H11, TIP41C, 2N3055/MJF3055/TIP3055. For MOSFETs you should be able to come up with a boatload of results if your voltage+current requirements are even remotely reasonable... what exactly have you been searching/filtering for?"
},
{
"post_id": "",
"author": "Capernicus",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "December 28, 2021, 01:35:17 pm",
"content": "Thats rated well above what I need. But thanks for the link!!My bot is only 10volt 1amp. Its amazing that one u showed is 300 watts, I bet that is twice as strong as a man.I wonder how big the motor is that goes with it.If you make a really strong one, then prob is the battery is going to drain 100 times faster, so have to put down a 6x6x6 matrix of 3000 farad super capacitors for that thing, to even last 10 minutes."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 28, 2021, 02:39:47 pm",
"content": "Quote from: Capernicus on December 28, 2021, 01:35:17 pmDoes not mean you need a 10W transistor though. Power rating is the maximum power transistor is allowed dissipate (generally not in free air). Nothing to do with power of the load."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 28, 2021, 06:39:29 pm",
"content": "That's RF power devices for you! Well not for you.. Switching MOSFETS are cheap- even halfway dcecent ones. Under a kiwi:https://nz.element14.com/infineon/irf520npbf/mosfet-n-100v-9-7a-to-220ab/dp/910303101Or For a couple of kiwis a monster:https://nz.element14.com/infineon/irf2804pbf/mosfet-n-40v-280a-to-220/dp/8657491It can only handle a measly 75A not 280A.But this will do you:https://nz.element14.com/infineon/irfr024npbf/mosfet-n-55v-16a-d-pak/dp/8649618"
}
] |
2025-10-17T17:17:27.555412
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100-dc-dc-for-grundig-microphone/
|
100 DC-DC For grundig microphone - Page 1
|
[
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2020, 02:46:58 am",
"content": "Hi All, Long time viewer, first time contributor. I am planning to build the circuit attached to power and use with the Grundig GCM3 Microphone. My question is how can i generate the 100v from the 9v without using 33 battery's. I am new to electronics and i have built a few kits and could do with some help with this. I read about a boost converter using a 555 but i am not sure if that wold be suitable.The microphone was a gift and as i am stuck inside (imunocompromised) i would like a nice project."
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2020, 03:38:02 am",
"content": "Welcome to the forumA common circuit for generating condenser mic capsule HV bias is a one-transistor Hartley oscillator with voltage multiplier afterwards. Early Schoeps CMC3 or CMC5 used it. Output is usually around 60VDC (7.5V power) but with 9V you can get more. Very little current is required, uA. The disadvantage compared to using a stack of coin batteries is the oscillator's output is not regulated unless the input is regulated - so it will drop as the 9V battery ages. It also has some RF noise but this is filtered and seems to work fine.These are circuits used by many mic manufacturers. MXL mic pic shows it as the second board on the far right, pic fromhttp://recordinghacks.com/microphones(you should send pics to them, they have no Grundig). The other mic schematics shows the bias voltage circuit.I was working on a small SMT Hartley oscillator pc board for mics but Mouser sold out of inductors so I have to find substitutes.Another method is a voltage multiplier using CMOS CD4049.Most important is how much room do you have?"
},
{
"post_id": "",
"author": "Circlotron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2020, 03:57:56 am",
"content": "If space is not a problem you could just join a whole lot of small 9 volt batteries in series. They clip together quite well. Get it going very quickly, and if it’s not a success you can always use the batteries for something else. Probably lower noise than an inverter too."
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2020, 08:40:34 am",
"content": "Have no limit on size but am hoping to put it all in a guitar pedal size enclosure. but tbh it could be any size. I know stacking batteries will work but there must be an way without."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2020, 05:27:09 pm",
"content": "I laughed at \"33 x CR2032\"; that sure is safe.Any oscillator circuit with a high voltage winding on the resonating inductor can work and results in low noise. A transformer based inverter is feasible as well. But since the inductor or transformer is not common, a micropower boost switching regulator can directly drive a capacitance multiplier to easy get to 100 volts."
},
{
"post_id": "",
"author": "chris_leyson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2020, 05:44:07 pm",
"content": "A dc-dc converter, something like thishttps://uk.rs-online.com/web/p/isolated-dc-dc-converters/7331102/If you go down this route you may want to go for a medically approved converter for safety reasons, low leakage current. EDIT: Sorry had my safety hat on, was thinking about leakage current."
},
{
"post_id": "",
"author": "gf",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2020, 06:31:32 pm",
"content": "Does it stringently need 100V, or would it work with the usual 48V phantom power over XLR as well? (Then it were powered from the mixer/amp, and no need for batteries at all.)"
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2020, 07:58:42 pm",
"content": "Apparently it doesnt work with 48v and only produces nice results up at round 100v. I have seen cap/diode doublers but how can i simply produce the ac? i cant design my own circuits yet so any pointers to online resources. I will look at rs but wanted to build the whole system myself if i can. it is my isolation challenge to get this mic to work."
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2020, 08:03:42 pm",
"content": "Quote from: chris_leyson on May 16, 2020, 05:44:07 pmThis looks a promising option but it is expensive and I would like to know how it works rather than just using sealed unit. but if all else fails it would be a solution"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2020, 08:23:22 pm",
"content": "If it's for the polarising voltage for a condenser microphone then the 33 lithium coin cells actually sounds like arelativelycompact and electrically very quiet solution. The only load will be insulation resistance (as indicated by the 500k series resistor in the schematic), so they should last for pretty much shelf-life.Just stack them in suitable insulated tube (or maybe two half sized stacks side by side) with a single compression spring and a suitably large series resistor. They don't need to be expensive cells for this application, just look for cheap ones on Amazon. CR2025s would save you some stack height too (2.5mm vs 3.2mm), 82.5mm total.The microphone might well have used a 90V dry cell radio HT battery originally.Edit: Qty 10 for £1.89 on ebay (with 5% multi-buy discount).Edit1: CR1616?"
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2020, 08:31:20 pm",
"content": "Quote from: Gyro on May 16, 2020, 08:23:22 pmI am starting to think this is getting to be my only option, What do you mean by \"suitably large series resistor\" isnt that what the 500k is for. I know the £1 shop sell packs of 20 but think might go little better quality"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2020, 08:38:19 pm",
"content": "Yes, it is, sorry, I wrote that bit before looking at the schematic (again).If you want really compact you could maybe try CR1616s but they might be more expensive as they are less common.P.S. Old Zamboni would have given his eye teeth for lithium coin cells!https://en.wikipedia.org/wiki/Zamboni_pile"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2020, 12:35:49 am",
"content": "Quote from: willeye on May 16, 2020, 07:58:42 pmCheck out figure 27 on page 18 of Linear Technology application note 45 for an example of how a boost converter can drive a capacitive voltage multiplier. The virtue of this particular implementation is that it can run on a single 3 or even 1.5 volt cell:https://www.analog.com/media/en/technical-documentation/application-notes/an45f.pdfR3 is the \"suitably large series resistor\" mentioned by Gyro and is there for safety as it limits the output current if the high voltage is applied to something delicate, like the user."
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 17, 2020, 09:33:55 am",
"content": "Quote from: Gyro on May 16, 2020, 08:23:22 pmWell i have ordered 40 cr1616 from ebay, that way i can build the circuit then i can test while I learn about doublers. So where does the 1m resistor go in this case?"
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 17, 2020, 09:40:20 am",
"content": "Quote from: David Hess on May 17, 2020, 12:35:49 amSo figure 27 cold be connected to a cap/diode doubler via the out but what is the +90v Bias mean"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2020, 10:37:08 am",
"content": "You could buy 8 A23 batteries :https://uk.farnell.com/gp-batteries/gp23a/battery-12v-38mah/dp/30040810 pcs for 4.5 pounds :https://www.amazon.co.uk/GP-Super-Voltage-Alkaline-Battery-Chrome-Black-Red/dp/B072FBK3P9/Should take up little space, but kinda lousy battery life, i don't know how many hours the mic is gonna run on a set of 8."
},
{
"post_id": "",
"author": "gf",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2020, 10:37:27 am",
"content": "Safety might be a secondary aim. But primarily, the series resistor between voltage source and condenser microphone capsule is supposed to ensure that (once the capacitor is charged) audio frequency variations of the capacity do not alter the charge, but rather lead to a changing voltage across the capacitor, which can be picked-up and amplified. So I'm surprised about the low value of only 500k. For a cut-off freqency of say 20Hz, this imples that the capsule capacitance would need to be >= 1/(500000*2*pi*20), i.e. >= ~15nF. Admitedly it's a mic with a large diaphragm, but is the capacitance really that high? Otherwise low-frequency performance suffers. I've seen other condenser mic amp schematics which rather used dozens of MOhm up to 1GOhm for the charging resistor, and similarly high values for the gate biasing resistor, too. Nevertheless it indeed seems that these old Grundig tape recorders feed the mic input via only 500kOhm, e.g. R10 inhttp://www.hifi-archiv.info/Grundig/TK5/tk5-16.JPGQuote from: willeye on May 17, 2020, 09:40:20 amThe left part of figure 27 already is the boost converter, including the doubler.You can likely change the divider R1/R2 a bit to get 100V instead of 90V.(The pulse generator at the right hand side of figure 27 is not part of the converter, you don't need it, it is just powered by the 90V generated by the converter)"
},
{
"post_id": "",
"author": "chris_leyson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2020, 10:47:01 am",
"content": "I really like the solution posted by David Hess, AN15 fig. 27. An external high voltage switch could also be used with the LT1073 as shown in fig. 29 which uses the LT1072. And thanks to gf post above pointing out the 500k series resistor the maximum available current is only 200uA."
},
{
"post_id": "",
"author": "gf",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2020, 11:20:51 am",
"content": "Quote from: chris_leyson on May 17, 2020, 10:47:01 amBut DC current is not an issue. Once the mic capsule capacitor is charged, there won't flow DC current any more. It is rather the converter's quescent current which drains the battery then, not its load.EDIT: When the mic capsule were biased directly from a battery, then this battery would last forever (almost - i.e. rather limited by self-discharge and leakage currents only), while the no-load quiescent current of the LT1073 is still 135..250µA. This relativizes of course, when we consider that the amp needs some power anyway."
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 17, 2020, 01:10:30 pm",
"content": "Thank you all for the help! I am learning so much. So if i understand I only need this part of theFigure 27. Do i need to do anything to smooth the output voltage. Would noise be transferred to the signal from mic. I will draw up a final design and order a lt1073. The batteries I have ordered can be a way of testing and a fall back. Does the inductor value have to be exact. I have some i have removed from other recycled boards. Is there a simple way to test an inductor.Would thishttps://www.ebay.co.uk/itm/10pcs-LT1073CS8-Micropower-DC-DC-Converter-Ajustable/261185316852?hash=item3ccfdba7f4:g:XggAAMXQLs5Rp0sLbe correct. It aslso says in the specs it can run upto 30v so could i run the whole thing off a 9v square battery"
},
{
"post_id": "",
"author": "gf",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2020, 04:29:14 pm",
"content": "Are you really sure that the mic won't work with 48V, too? (besides giving a ~6dB lower signal)Looking around in the web, I found the following two circuits interesting.Both pretty simple, still just a few components, directly powered over XLR from the mixer, no battery, no voltage converter.http://www.audioimprov.com/AudioImprov/Mics/Entries/2016/3/4_Johnny_Zhivagos_Lika.htmlhttp://www.audioimprov.com/AudioImprov/Mics/Entries/2017/5/7_Schoctava%2C_a_simple_mic_circuit.html(The second one may not be an option if one side of the capsule is undetachably connected to ground.)"
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 17, 2020, 06:56:37 pm",
"content": "Quote from: gf on May 17, 2020, 04:29:14 pmEverything I have read has said 48v works but does not allow the mic sing to full potential. As this is a project for fun i am going to keep trying to get as good a result as i can. There are only one wire from the mic and the shield. Obviously all i can get is anecdotal info so i think if i use the original schismatics as a start i can hopefully make something nice."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 18, 2020, 03:57:33 pm",
"content": "Quote from: willeye on May 17, 2020, 01:10:30 pmThat is correct.QuoteNoise may be a problem so I would add an RC filter before the load by dividing the high value current limiting resistor into two parts and placing a capacitor between them to ground.QuoteThe inductor needs to be able to support the full switching current from the LT1073 without saturating but is otherwise not critical. The LT1073 datasheet has details."
},
{
"post_id": "",
"author": "gf",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2020, 03:57:06 pm",
"content": "@willeye, here is yet another low-current voltage multplier from CMOS invertes:http://gyraf.dk/schematics/Voltage_multipliers_with_CMOS_gates.pdfBtw, did you watch the EEVblog microphone video series?Quite a couple of (proven) circuit ideas are sketched here.[ It's actually a playlist of seven videos, IIRC, but the board software inserts only the first video into the message. At YouTube you can search for \"EEVBlog Microphone Series\" ]Quote from: willeye on May 17, 2020, 06:56:37 pmAs \"original schematic\" I'd consider the tube preamp in the Grundig tape recorders, to which these microphone models are supposed to be connected. But I'm not sure that Grundig's aim was the best result one can get from this microphone capsule. My feeling is that they rather had a different design goal in mind: Unlike other high quality microphone manufacturers they wanted torenounce a (tube?) preamp inside the microphone enclosure(I guess for cost reasons), so they rather did make some compromises in favor of this goal. Note, for best results one would rather not have a long cable from an condenser microphone capsule to the preamp (but the preamp would reside directly in the mic enclosure, close to the capsule), and one would not charge/load the capsule with such a low impedance either (500kis lowfor a condenser microphone capsule).EDIT:One fundamental question is of course whether to keep the gadget itself untouched, for historic preservation reasons, or whether to modernize it."
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 20, 2020, 11:28:15 am",
"content": "Quote from: gf on May 19, 2020, 03:57:06 pmI have been watching those videos over and over and I am learning so much and am starting to understand the parts of the circuit. Parts have started to arrive so I will start to breadboard it.I can see that Grundigs goals might not have been to get the best out of it but mine are, It is such a nice looking thing and there are quite a lot of them about so it feels like a good project.I will experiment with the 500k resistor once it is breadboarded to see if I can improve the response after the info in the episodes above. Looking at some Grundig schematics it always has the 500k but it often is accross a 3m /2m resistor divider so the final resistance on the load looks like 2.5m on some but maybe i havent read them right.I have a din socket on the way so I should be able to build this as a module that has no impact on the mic and wont require modification.One video that helped a lot wasseeing it step by step and explaining every part of the circuit is amazing."
},
{
"post_id": "",
"author": "gf",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 20, 2020, 04:43:17 pm",
"content": "Quote from: willeye on May 20, 2020, 11:28:15 amIn the TK5 schematic I see a 3M/5M divider feeding the 500k resistor, but connected to the center tap there is also a bypass capacitor (C35=50nF), shorting AC to ground (cut-off ~6Hz). So the divider resistors don't play a role for AC at audio frequencies.EDIT:Where do you actually want to connect the mic? To home audio / PC sound card, or rather to a mixer with XLR microphone inputs?"
},
{
"post_id": "",
"author": "willeye",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 21, 2020, 11:57:31 am",
"content": "Quote from: gf on May 20, 2020, 04:43:17 pmI am planning to use both on my mixer and on my pc via either a di box or a xlr to 3.5 cable, have both. Most of the parts have now arrived and I have put together then main circuitand just waiting for some 16mm ID tube to build the battery and the 400v cap. First time I have worked with jfets."
}
] |
2025-10-17T17:49:35.034702
| 27
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100-ohms-differential-pairs-impedance-matching-length-matching/
|
100 ohms differential pairs impedance matching + length matching - Page 1
|
[
{
"post_id": "",
"author": "VEGETA",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "September 25, 2021, 12:47:55 pm",
"content": "Hello,I want to route high speed digital signals of 600 mhz and 6 ghz. datasheets and design guides strictly says it should be 100 ohms differential impedance. I also want to length matching them. I am using KiCAD, can't\\won't use any other package.I used 0.1 trace width and 0.2 spacing (i though it is 0.3 but it is actually 0.2). my PCB vendor is AllPCB and their 4-layer stackup shows pre-prep is 0.122mm of heighthttps://www.allpcb.com/4_layer_pcb.htmlI plugged these numbers in Kicad calculator and it showed like in attached picture.I already routed these signals, was very tiresome to length match them!please inform me what to do to achieve the requirements... and what is the best approach professional designers use in order to do it.I mean, you don't design the board multiple times to be able to fit all PCB manufacturers with their different stackups right? or do you specify a custom stackup all the time if you are doing it for professional job.. and is it really much expensive?does length matching has to do with this?I had to put vias (0.3mm size) for nearly half of these diff. pairs... will this affect anything?for your kind help!NOTE: attached picture was for 0.3 gap which is not correct, correct one is 0.2mm. for 0.2mm kicad says Zodd= 68 ohms which is not going to be 100 ohms diff... i need it to be 50 ohms.EDIT: I achieved 50 ohms Zodd by making 0.15mm width and 0.1mm spacing, but i feel these are too close and too small... is this correct to choose?thanks!"
},
{
"post_id": "",
"author": "VEGETA",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "September 25, 2021, 01:11:44 pm",
"content": "reference board has this:width of trace: 0.1 mmspacing: 0.2 mm (= actual space between the 2 tracks, not from track center to track center).which is like mine.but their stackup specs are the following:prepreg height: 60 um.copper height: 18 um. (mine is standard 35).I plugged them on kicad calculator and it turns out to have around 51.75 ohms Zodd. seems about correct right?___I might be wrong about reference stackup, therefore I attached the sheet showing its details. please correct me"
},
{
"post_id": "",
"author": "VEGETA",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "September 25, 2021, 05:10:03 pm",
"content": "I looked around and found that I used 0.1mm trace with 0.2mm gap + 0.122mm prepreg thickness and 35um copper thickness... both kicad and saturn pcb tool showed around 100-103 ohms differential which is nice! also, all signals are length matched with help of 0.3mm vias. is there anything else i need to worry about? please inform me.Now for single signals (not differential), there are 60 of them which needs to be 50 ohms. kicad shows 0.2mm to be suitable (=51.1 ohms) while saturn shows around 0.19mm (50.1 ohms). gonna go with saturn calculations and modify the tracks.what do you think or recommend?"
}
] |
2025-10-17T17:22:10.096777
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1000-eur-oscilloscope/
|
1000 EUR Oscilloscope - Page 1
|
[
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 10, 2023, 01:18:06 am",
"content": "Hi All,it appears that this year my new hobby company brought some income and I would like to use the revenue to get some equipment home.I have about a 1000 euro that I would like to spend for an oscilloscope. I know that the model depends on what I am going to use it for and for me it's a tough question. I would like to get into electronics and luckily have the budget to spend. I'd like to look into the servo motors and the RF devices and understand better how things work. Thus It should probably be a well rounded scope that will last me for the next 10years or so as i will learn etc.Was looking at Rigol DHO924Shttps://rigolshop.eu/dho924s.htmlas it's just a good fit for the budget but maybe there are deferent things I should look at and consider ?PS.please It'äs a bit of a luxury problem. I don't want to go cheap. I want to spend 1000 eur on the company hardware, otherwise they will be gone in food or taxes and all that."
},
{
"post_id": "",
"author": "MarkT",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 02:23:24 am",
"content": "It looks like the Siglent model at that price point is one of the SDS2000X series - probably worth comparing to the Rigol.Many modern RF devices are way out of reach of a budget scope, note. Even ISM bands go upto 915MHz, WiFi starts at 2.4GHz, etc. A spectrum analyzer is more appropriate in many cases for RF work."
},
{
"post_id": "",
"author": "u666sa",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 04:33:44 am",
"content": "I heard from dudes rigols are noisy. Which further reafirmed by purchase decision. SDS1104X-E, and you can hack it to 200 MHz. You can even go extra cheap and still get a good one. You can even get Owon HDS2202S for like really cheaphttps://aliexpress.ru/item/1005003764438360.htmlLet's face it. You don't need an expensive oscilloscope. It's not used often. Most of the time it will be sitting collecting dust. In repair industry for me, last time I used it was yesterday, to check the clock on memory chip. Before that, I wasn't using it perhaps two weeks.And you will have to be comparing local buying options VS. foreign. Because of customs."
},
{
"post_id": "",
"author": "JeremyC",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 05:32:47 am",
"content": "Quote from: De on December 10, 2023, 01:18:06 amIf you are targeting 12 bit scopes the DHO924S maybe good option. I suggest to check threads about hacking the 914 to 924,it may save you ~100 euro.I believe the noise front end in Rigol scopes applied to the older 8 bit series.If you can wait 1 - 2 months check also the new SDS800 HD series from Siglent.If you don’t have needs for 12 bit scope I would recommend the Siglent SDS2104X Plus, you can easily convert it in 500MHz scope (check thread on EEVblog). However it’s a little bit more than 1000 euro.In my opinion Siglent scopes have the best FFT implementation on the market.Good luck..."
},
{
"post_id": "",
"author": "jonpaul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 10:41:16 am",
"content": "I would avoid the digitals till you learn on an anglog scopeA 2 ch 10 or 20 MHz fine for basic beginner use.We Got three analog Hameg scopes in EU for between EU 5...40.Go to the modern digital after you are experienced on an analog scope.j"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 11:14:06 am",
"content": "Quote from: MarkT on December 10, 2023, 02:23:24 amThe ISM bands go way beyond 915MHz. DECT, Zigbee, Wi-Fi and Bluetooth, among many different unlicensed radio systems, by design operate in ISM bands. That’s why you don’t need a license for your Wi-Fi router and Bluetooth mouse.The highest worldwide ISM band is 24GHz, but in some areas higher bands, up to 244GHz, are allocated."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 11:14:59 am",
"content": "Quote from: jonpaul on December 10, 2023, 10:41:16 amCompletely pointless advice IMHO. I don’t see any advantage whatsoever in starting with an analog scope."
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 11:55:15 am",
"content": "Quote from: tooki on December 10, 2023, 11:14:59 amThis. Here's better advice: as always, ignore jonpaul."
},
{
"post_id": "",
"author": "jonpaul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 03:44:43 pm",
"content": "Hi: Really rude comments... Advantages of analog scope for a beginner:Walk before you can run...Save $Learnavoid issues in digital scopesj"
},
{
"post_id": "",
"author": "langwadt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 05:00:20 pm",
"content": "Quote from: jonpaul on December 10, 2023, 03:44:43 pmNone, what so ever"
},
{
"post_id": "",
"author": "u666sa",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 10, 2023, 08:57:19 pm",
"content": "Scopes takes about three weeks to catch up, perhaps faster if you use it often. It's simplier than TI-83 calculator.Some advanced stuff will come later down the road of course, no big deal."
},
{
"post_id": "",
"author": "Haenk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 11, 2023, 01:52:38 pm",
"content": "Quote from: tooki on December 10, 2023, 11:14:59 amActually, there is!If you kill your scope while trying things out, it's not a huge loss, just buy another one for cheap.Whole different story if you kill your 1k scope on the second day(Other than that, there really is no point in going vintage.)"
},
{
"post_id": "",
"author": "Zenith",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 11, 2023, 02:13:04 pm",
"content": "Quote from: tooki on December 10, 2023, 11:14:59 amEasy to use, cheap and good enough for a lot of things. I have both a DSO and analogue scopes and I usually use the DSO. It's small and comes with nice extras such as a good enough for most things frequency counter and voltage readouts. For some things an analogue scope is nicer.In this case it sounds as if it's the O/P's first scope and he doesn't know that much about them. He doesn't have a clear definition of his needs. Just because he wants a scope and has 1,000 € to spend, doesn't mean it's a great idea to splash it all on a scope."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 12, 2023, 08:33:01 pm",
"content": "Quote from: jonpaul on December 10, 2023, 03:44:43 pmUsed DSOs exist, too.I disagree 1000% with your characterization of operating a DSO as “running” while analog is “walking”. I think a DSO is, ultimately, more beginner-friendly than an analog scope. If you’re stuck, you can always press “autoset” to at least get you to some kind of recognizable state. A beginner on an analog scope can easily be in a configuration they don’t know how to get out of, other than completely randomly pressing buttons and turning knobs.Analog scopes have “issues” (=limitations), too. And many of them are really significant, like not being able to do a single trigger and hold the image of a transient event for subsequent observation. (Analog storage oscilloscopes did exist, but were exotic and spectacularly expensive devices. One of those today, used, is probably worth more than a basic new DSO, as a museum piece.) They’re much larger and heavier. Usually only 2 channels, while most DSOs have 4.I feel like you’re basically advocating “hazing by CRO”. But IMHO an appeal to tradition is not in itself a valid argument."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 12, 2023, 08:33:49 pm",
"content": "Quote from: Haenk on December 11, 2023, 01:52:38 pmIf blowing it up is a concern, one could buy a used DSO…"
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 13, 2023, 09:21:28 am",
"content": "Analog scopes can still do what they used to do for the last 50 to 100 years, but the only sensible argument for buying an analog scope is if it some second hand thing for EUR 50, or maybe up to EUR100 if it is a really fancy one.But a more important question is: Do you already have experience with an oscilloscope, or is this your first one?I recently bought a new Siglent SDS1104X-E (100MHz, 4 channel) scope. I paid around EUR460 for it and it is already more scope then I would need. My previous scope was a Rigol DS1052E and I never liked it much. On-screen measurements and FFT are so bad on that thing it's unusable, and it's rotary encoders started glitching within a few months.But why spend EUR 1000? Pretty decent digital scopes start around EUR350 new. EUR 1000 is a bit of a difficult budget, It's easy to buy more scope then you need, or the wrong one. EUR1000 is also still quite low if you're interested in a \"traditional western brand\" oscilloscope.I also see the scope you selected has 16 digital channels. That is nice to have of course, but I bought a separate logic analyzer (Kings LA2016 16 channels 200Msps EUR130) There is an advantage of having both analog and digital in the same device, but I find the price difference too big. I also prefer the much bigger PC monitor and mouse + keyboard navigation for a logic analyzer.My gut feeling is you get an lot of oscilloscope for EUR500, and EUR1000 does not get you much more. Especially Rigol & Siglent are fighting in the \"entry market\", and they probably can't make much profit there, while for EUR1000, you get a bit more bandwidth and some digital channels. (Total BOM cost probably less then EUR 50) and most of the money goes to their profit margins."
},
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 13, 2023, 11:14:28 pm",
"content": "good reasoning but some models for my undefined needs would be very appreciated."
},
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 13, 2023, 11:18:23 pm",
"content": "Quote from: Zenith on December 11, 2023, 02:13:04 pmI literally beg you to be specific, if you can formulate a need for me please go ahead and suggest the alternative equipment..."
},
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 13, 2023, 11:24:36 pm",
"content": "Quote from: JeremyC on December 10, 2023, 05:32:47 amThank you!Siglent SDS2104X Plus looks still within the reach. It's 1200 eur. Without the bundle pack that they offer now for extra 250 or so.What would be a better investment for the future , Siglent SDS2104X Plus or DHO924S , from your point ?"
},
{
"post_id": "",
"author": "jonpaul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 14, 2023, 12:02:53 am",
"content": "Rebbonjour a tous:I have used both analog CRT and digital scopes and each has its place.The analog CRT are gernerally more robust and have no issues in aliasing, quantization, and generally less noise than digital.We prefer TEK analog especially the last (and very best!) CRT, 2465B, 2467B.For digital we have had Yokogawa Japanese scipes sicne 1993.Easy to use, fine connectivity and well designed.In EU we have found several German Hameg HM series andalog, HM103, HM203 and HM204 for EU 5>>25>>40.You can sonetiems firnd bargins at flea markets, ham radio meets and siletn key auctions.Beware that analog scopes are typically easy to damage in shipment, the glass CRT.Bon chance!Jon"
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 14, 2023, 04:48:45 am",
"content": "Quote from: De on December 13, 2023, 11:24:36 pmI have no hands on experience with the Rigol but see it's only advantage over the SDS2104XP being the 12 bits and the HDMI out. I hear the Rigol can be \"persuaded\" to operate at 200MHz but the Siglent can be \"improved\" for no cost to over 600MHz. THis will be a lot better for RF needs. The Siglent does have a 10 bit mode too at reduced BW, but if 12 bits is paramount to your needs then the Rigol would be best. For me the 600MHz bandwidth is far more important than the 12 bit resolution of the Rigol.Also, it may just be my opinion, but the Rigol seems like a toy. It's tiny, noisy and has an external power supply and some have noted that it's UI is not yet very polished. They may improve that over time with firmware updates, but it seems apparent Rigol have a track record of not doing that.Support is another consideration. I'm not familiar with Rigol support, but the support I get from Siglent is amazing. They give me the best support I have ever gotten on any product I have ever worked with. Personally or professionally.You need to do some homework and decide what it is you really want, but from your initial post I'd have to suggest the Siglent. If you can swing the additional cost and really want the 12 bits, look at the SDS2104X HD. It offers the beat of both."
},
{
"post_id": "",
"author": "Zenith",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 14, 2023, 05:03:25 am",
"content": "Quote from: De on December 13, 2023, 11:18:23 pmUnfortunately my crystal ball is away at the cleaners. You ought to know the sort of things you are interested in and want to investigate. If you want to spend €1,000 on an oscilloscope look at the Rigol or Siglent closest to €1,000 and buy that. Spend between €400 and €500 on the scope, which for most of us would be more than adequate, and you have about the same to spend on other things, such as a function generator, power supply, very good digital multimeter, or whatever combination fits your needs and budget.If you are learning basic electronics, oscillators, amplifiers, filters, op amps etc, then a used 20MHz Hameg for €50 will take you a long way, and you certainly don't need to spend €1,000."
},
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 16, 2023, 04:48:04 pm",
"content": "Quote from: Zenith on December 14, 2023, 05:03:25 amWell, this still leaves me with exact same question i had at the beginning.However I am looking now at the SDS2104X Plus as well"
},
{
"post_id": "",
"author": "Wallace Gasiewicz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 16, 2023, 05:25:15 pm",
"content": "I THINK that the Sigilent scopes appear to be the best buy for the buck, bought NEW.If you say you have to burn 1K EUR especially.Watch the Scope tutorial at the top of the page first. Make a list of functions you think you want.Then look at the functions available on the scopes you are considering., Then look for discounts..I have only owned 20 scopes and use a Digital Agilent 54820 scope at present. These are getting old and are big, but seem to work fine. They are still expensive used. Maybe someone would comment on their capabilities as compared to Sigilent...CRT scopes are getting old also I have two, a Tek and an HP 1980, which cost 20K USD when new in 1985.There are still good reasons to have an analog scope (the 1980 is advertised as Digital).To us ole timers the new scopes can be aggravating because their controls are different or at least respond differently and you can get different traces with different sampling etc... But there is always the autoscope function.....Make sure the scope has the functions that you think you will need or like. An example is a 50 ohm input setting. Ability to use an external monitor maybe... maybe a bigger footprint if you want it to sit still on the bench and not move around when you use the cables....etcThe Fournier Functions on scopes I have seen are much better than nothing but not as good as a cheap SpectrumAnalyzer. A really cheap Logic Analyzer is better than the ones in scopes.So I would buy a scope based on its scope functions first. Then secondarily worry about it's Logic Ability. They pretty much all come with FFT, some much better than others.Also consider probe costs. There are lots of cheap knock off probes that arereally goodif you are under 500 MHzz, above 500. More Expensive.I do think that buying a cheap analog and learning is a good idea, but also we are in the 21st century and analog scopes are kinda antiques....and too many need repair. And you are telling us you need to make the purchase soon rather than wait to learn how to use an old scope.Good Luck!!!"
},
{
"post_id": "",
"author": "Solder_Junkie",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 16, 2023, 07:14:29 pm",
"content": "As both a home builder of equipment, and someone who spent their working life repairing electronic equipment for a major European manufacturer (who also made oscilloscopes), perhaps I can make a suggestion or two…Chinese ‘scopes are “OK” for home use, but are cheaply made. I have a Rigol DS1054z, the good points are:Low cost4 channels which can be handy at timesDoesn’t take up much space, easy and light to carry.The 1054z used to be easily “hacked” to 100 MHz and give extra features (maybe can still be done). The hack could be reversed in case of needing repair.The bad points:The supplied probes are poor, factor in the cost of buying a set of better ones.The rotary encoders are poor, one of mine has become intermittent.Regarding those advocating buying an analog scope to start with, check the mainstream manufacturers… you won’t find one, the world and his dog use digital scopes, they are easier to use and the triggering is vastly superior. Knowing what signal to expect, I can preset my Rigol and capture a transient event “1st go”, and have it stay on the screen, which isn’t something an old analog would manage.Personally, and as suggested by others, unless you have a real need, don’t waste money on an expensive scope, even in the service industry they tend to gather dust on the workshop shelf. 500 euros should easily get you something useful. Put the spare cash into a decent multimeter (a USA made Fluke with a lifetime warranty, that won’t burst into flames when you test the mains supply on Ohms) and a good soldering station (Hakko or Weller).SJ"
},
{
"post_id": "",
"author": "schmitt trigger",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 16, 2023, 07:32:00 pm",
"content": "Excellent idea to invest in your own company instead of giving the money away to the taxman.If you ask twenty people for an opinion, you will get twenty-one different opinions. Keeping that in mind, I'll give my own personal opinion, which can be as relevant,or not,as the others:-Depending on the electronics field you are working on, you may find the need for specialty probes. They can be diff probes, current probes, active Hi-Z probes, passive hi-voltage probes, you name it.For me, which I work a lot with power electronics, a diff and a current probe are a must. Consider in your budget a specialty probe."
},
{
"post_id": "",
"author": "Zenith",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 16, 2023, 11:50:54 pm",
"content": "Quote from: De on December 16, 2023, 04:48:04 pmA perennial problem. What would you like, what can you afford, (in this case €1,000), and what would fit your needs exactly? Should you be of unlimited resources would a Infiniium UXR‑Series Oscilloscope with 110GHz bandwidth be a sensible and enjoyable thing to own?Were you my brother, I'd be happy to loan you a nice little 40MHz analogue Hitachi scope while you mulled over the question. I believe it would keep you happy for quite a time.The Siglent SDS2104X Plus looks like a formidable instrument for the price, even if it's stretching your €1,000 price, and the innovative licensing arrangements, looked into in depth on this forum, should not be overlooked."
},
{
"post_id": "",
"author": "Wallace Gasiewicz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2023, 12:17:18 am",
"content": "Here are some in the UK, in our buy and sell :https://www.eevblog.com/forum/buysellwanted/labtronix-sell-off-of-siglent-equipment/msg5202747/#msg5202747"
},
{
"post_id": "",
"author": "nightfire",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 17, 2023, 12:21:42 am",
"content": "Another approach: Get some scope for a bit less than 1000 Euros, that maybe has some decent resale value, and get some needed accessoires like a differential probe, when you have to probe inside power supply parts etc.Or a PCB holder or that stuff."
},
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 02:44:32 am",
"content": "Quote from: Wallace Gasiewicz on December 16, 2023, 05:25:15 pmHej, where is the scope tutorial ?"
},
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 02:45:56 am",
"content": "Quote from: Solder_Junkie on December 16, 2023, 07:14:29 pmI do own a couple of great Flukes and a good soldering station!What would be the scopes you would recommend then, as a person who saw them \"from the inside\" ?"
},
{
"post_id": "",
"author": "De",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 02:51:46 am",
"content": "Quote from: nightfire on December 17, 2023, 12:21:42 amwill appreciate any specific model of the scope that you can recommend"
},
{
"post_id": "",
"author": "Solder_Junkie",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 09:06:00 am",
"content": "“ What would be the scopes you would recommend then, as a person who saw them \"from the inside\" ?”The problem is that an entry level oscilloscope from Rohde & Schwarz will only give you 2 channels and 50 MHz bandwidth for €1300 (inc vat). Such prices are not a problem if you are equipping the workshop of a European company who can offset the cost against tax and enjoy the support of a serious test equipment manufacturer.A retired home user, like myself, has to consider the cost more carefully. You get 4 channels and 100 MHz from Rigol or Siglent for less than half the cost of the lower specification R&S oscilloscope. In addition, the Chinese oscilloscopes include a lot of decoding features for free, these features come as additional expensive options with R&S.In the past year I used my oscilloscope 3 or 4 times, my Fluke 177 is used every week. An oscilloscope gathers a lot of dust…SH"
}
] |
2025-10-17T16:42:40.922699
| 33
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10001-step-up-transformer-frequency/
|
1000:1 step up transformer frequency - Page 1
|
[
{
"post_id": "",
"author": "robowaffe",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 27, 2023, 09:37:51 am",
"content": "so as far as i can tell now, step up transformers take more wire to make than a 1:1 isolation transformer.that means they have more henrys and more load than 1:1 transformers?so when someone is talking about a high frequency step up transformer like this->10kv.https://www.aliexpress.com/item/1005002038574313.html?pdp_npi=2%40dis%21AUD%21AU%240.60%21AU%240.51%21%21%21%21%21%402101c5c216904506568384363eba10%2112000018505117655%21btf&_t=pvid:74f2abb1-59c4-4d6b-afbb-6e11e112965f&afTraceInfo=1005002038574313__pc__pcBridgePPC__xxxxxx__1690450657&spm=a2g0o.ppclist.product.mainProductIve got 3 questions.* what is the dc resistance of its coils* what is the henry's* what is this frequency probably going to be?"
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2023, 11:41:17 am",
"content": "1 & 2 is impossible to tell. You either read manufacturer's datasheet or buy this transformer and measure yourself.3. The frequency will be whatever you choose it to be. Theoretically you can drive the transformer at any frequency you like. Practically the core material and construction of the transformer defines optimal frequency range where efficiency will be highest. Much lower or much higher frequency will make a transformer to not function as intended. Judging from the picture this one is likely intended to work at around 10's of kHz."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2023, 12:44:02 pm",
"content": "I dont think that you have fully understood how transfomers work. How the Magnetic flux created in the primary couples via the magnetic circuit into the secondary. Indcutance is not a parameter your aimaing at. Once you have established the ratio, you need to determine the flux density (B). Then you design a core that will operate at the peak flux density.The primary and secondary in a step up transformer will have different indcutances.When a simple transformer is under load the net inductance is essentally zero.All the flux from the primary \"indcutance\" is coupled into the secondary indcutance.Some transfomers are designed so that the coupling factor (k) is somewhat less than unity.This creates extra inductance- these areoften refered to as leakage transformer. They were very popular in lighting circuits. Step up and balast all in one lump.The number of turns is determined by the flux density you want to create in the magnetic circuit.If you dont know what that number is, or anything about the frequency, core dimensions or material its impossible to say.Tutorial attached."
},
{
"post_id": "",
"author": "robowaffe",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 27, 2023, 01:41:47 pm",
"content": "Thanks for the toot, I'm reading it now.isnt the frequency of the transformer dependant on its henry's?and isnt the number of winds increasing the henry's?"
},
{
"post_id": "",
"author": "CaptDon",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2023, 12:49:37 am",
"content": "It is nearly impossible to answer your ambiguous questions here. Just go googling about the internet and learn about transformers and inductors from companies that specialize in building them and have online guides for choosing materials and doing calculations. Using iron wire would NOT produce more inductance in a given core vs. copper wire. It would produce large inefficiencies and most likely wasted heat energy."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2023, 10:01:59 am",
"content": "Quote from: robowaffe on July 27, 2023, 09:37:51 amWhat gives you that idea?Two transformers, of the same power rating and frequency, typically have similar quantities of copper and iron.A step-up transformer boosts the voltage and reduces the current.A step-down transformer boosts the current and reduces the voltage.An isolation transformer theoretically has the same current in the primary and secondary windings. In reality, there's some loss, so it's not perfect, but don't worry about it at this stage.The higher the current, the thicker the wire needs to be. A step-up transformer will have thinner wire on the secondary winding than the primary. An isolation transformer will have the same thickness wire on both the primary and secondary."
},
{
"post_id": "",
"author": "robowaffe",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "July 29, 2023, 10:12:18 am",
"content": "I think that because a step up transformer has asymmetrical windings so it ends needing more wire, but I dont know for sure.But I spose if one wire is thicker than the other I guess it would balance out."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2023, 10:14:23 am",
"content": "Quote from: robowaffe on July 29, 2023, 10:12:18 amIt doesn't need such thicker wire on the secondary, because it reduces the current. I added a bit more to my previous post, because I left out that part."
}
] |
2025-10-17T16:50:39.642393
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1000v-rectifier-for-24v-linear-power-supply/
|
1000V rectifier for 24V linear power supply? - Page 1
|
[
{
"post_id": "",
"author": "webgiorgio",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 04, 2018, 04:09:33 pm",
"content": "I am selecting the H bridge rectifier for the low voltage side of a transformer 220/24Vac 5A.I would pick a 100-200V rectifier, and I want to minimize the thermal loss of the H bridge.I would expect that the silicon is thicker for a diode with higher reverse voltage, but if you look at this datasheet (https://www.diodes.com/assets/Datasheets/ds21221.pdfGBJ2510), you see that the Vforward=1.05V for any Vreverse from 50V to 1000V.Why diodes with different reverse voltage have the same Vforward?I see that 1000V bridge rectifiers are more easily available on ebay than 100-200V. Is it a bad design if I use a 1000V version? (as far of the datasheet I would say no)."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 04, 2018, 04:14:29 pm",
"content": "Not a bad design to use 1000V, just overkill.Look at diode theory for answer to Vbr vs Vf on diodes, these parametersare predicted by different physical properties.Google \"diode theory\" or look at the books onwww.archive.orgRgards, Dana."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 04, 2018, 04:40:00 pm",
"content": "Forward voltage is always given as \"typical\", and generally also depends on the current flow, so it is given at the full rated current. As you are using a 25A bridge, the peak current through it will be nicely derated, so the actual forward voltage drop will be lower, probably at around 0.9V, being roughly the forward voltage at the 10A mark, when used as a full bridge rectifier with capacitive load. As to the actual unit, the forward voltage difference between a 50V and a 1000V is likely to be zero, as they make only one diode design for the units, and bin them during test for forward voltage drop ( to find those that are super leaky and get rid of them) and reverse voltage drop at around 0.5mA with a 1000V compliance voltage, to get an idea as to breakdown voltage, and then bin them for voltage. The binning generally, with a known process with good history and well known equipment, tends to be towards the top, 1000V devices being all that comes out, so while there might be devices made with lower voltage ratings in the part number, they all will probably pass the 1000V mark in most cases, unless they had a poor day at the foundry and actually made a not too good load of wafers by accident that did not meet the 1kV spec, but tested out lower. They all start off as GBJ2510 devices, but some either failed final voltage test and were labelled appropriately, or they had an order for the part and simply used the good stock with a lower label, as they do meet or exceed the required spec.Poorly kept secret is that a 1kV diode like 1N4007 could be any die that exceeds 1kV, some might be 1500V, some 1800V but all will be 1000V capable at 125C die temperature. You can be reasonably sure that at room temp all will withstand 1200V though, but make no assumptions on that, they make terrible voltage reference avalanche diodes."
},
{
"post_id": "",
"author": "davy peleman",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "February 04, 2018, 06:41:53 pm",
"content": "the same in my country. the 1000 volt ones are more common and less expensive than the weaker bridge rectifiers. really unlogical. so i also buy the 1000 volt ones. really strange a strange fact."
}
] |
2025-10-17T18:39:09.427659
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100k-digipot-only-reaches-63k/
|
100k Digipot only reaches 63k - Page 1
|
[
{
"post_id": "",
"author": "cyrix2000",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "November 30, 2022, 11:29:44 pm",
"content": "Hi,I'm wondering what I'm doing wrong here...I have MCP42100 DigiPot connected via SPI to a RaspberryPi. The control works but I can't get it to go above around 63K (even if I measure between the PA and PB terminals which should always be 100k I'm only getting 63k. Throughout the whole range it is outputting lower resistances than it should and maxes out at 63k. I tried to different MCP42100 both with the same effect, so I guess it isn't an equipment error but more an user error. The supply voltage provide by the RPi is 5V.So what am I doing wrong here? I'm using a multi-meter to check the resistance between PA and PB or PA and PW."
},
{
"post_id": "",
"author": "thm_w",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 01, 2022, 12:11:01 am",
"content": "Where did you purchase the IC from?Did you tie pin \"B\" to ground when measuring?Anything else connected? Is the MCP42100 on a SMD breakout or something."
},
{
"post_id": "",
"author": "Geoff-AU",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 01, 2022, 12:37:00 am",
"content": "PAx to PBx should be 100k regardless of wiper setting. Make sure you never apply any voltage outside the Vss to Vdd range to any of the potentiometer pins. If you sourced it from a reputable vendor (eg Digikey/Mouser) then it is likely user error, if you bought it from grey market (ebay, aliexpress, etc) it is probably a counterfeit part."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 01, 2022, 01:01:43 am",
"content": "Quote from: Geoff-AU on December 01, 2022, 12:37:00 amEnd to end resistance range is 70k-130k, so the OP's measurement isn't quite as far out as it seems. Datasheet shows measurement performed with the B terminal referenced to a fixed voltage (0-Vdd) rather than floating, so the OP should replicate that."
},
{
"post_id": "",
"author": "Geoff-AU",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 02, 2022, 01:26:26 am",
"content": "oh yeah, I missed that. Gee those are fairly loose tolerances. Better used as a voltage divider then it doesn't matter aside from circuit loading (not usually a critical parameter for a divider)"
},
{
"post_id": "",
"author": "EPAIII",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 02, 2022, 02:05:03 am",
"content": "I have seen specs for actual pots that were intended for the radio-TV repair industry where the overall resistance spec was +100/-50%. They would work quite nicely as volume, tone, horizontal lock, etc. controls. And were probably the same spec as the OEM parts. So 63K doesn't sound that shocking to me.Quote from: mikerj on December 01, 2022, 01:01:43 am"
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 02, 2022, 05:39:13 am",
"content": "That 70-130K is also only at room temp. The 800 ppm/deg C tempco will add another few percent at anything but dead on room temp. Also note that the wiper resistance is 250 ohms max.Digital pots are mainly used as \"potential dividers\" rather than variable resistors- the difference is subtle. The wiper output will track well with the digital code but the end to end resistance is poorly toleranced especially on these high value guys. You should also lightly load the wiper so the wiper resistance doesn't get in the way.Believe it or not, making large accurate resistors on chip is very expensive. They need to be long and skinny and there are tolerances involved all which take up IC area. They track well but they have poor tolerances. The only way to get really good R's on chip is to laser trim which is super expensive.Note that the lower resistance variants of the parts have somewhat better tolerances (their 10k is +-20% end to end at room).The microchip parts are designed to be very low cost, there are fancier pots from ADI/Maxim that have tighter end to end tolerances- (as good as 1%)You can also get clever by putting fixed R's around the digipots to tailor them for what you want. Maxim had an app note on these kind of tricks."
},
{
"post_id": "",
"author": "cyrix2000",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 02, 2022, 08:02:45 am",
"content": "Hi,thanks for all the advice. One thing I missed was grounding the output side when measuring it. After doing that, the end-to-end value improved to 92k which is more acceptable.I guess what I'll need to do is more or less generate a table of resistance for each of the 256 wiper positions and work with that. I hope these are at least somehow repeatable."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 02, 2022, 11:11:11 am",
"content": "Quote from: cyrix2000 on December 02, 2022, 08:02:45 amThey should be repeatable given the same operating conditions. Don't forget the rather high temperature coefficient of this part, a nominal 800ppm works out around 74 ohms/Celsius for your part which doesn't seem much, but if this will be used outdoors or in a non-heated building you could see 30C change or more over the seasons which may be significant for your application."
},
{
"post_id": "",
"author": "WattsThat",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 02, 2022, 11:36:26 am",
"content": "QuoteStarting to sound like an X-Y problem.Why do you care about the absolute resistance? It’s a potentiometer and when used correctly, absolute value should not mater. If you need a programable resistor, there maybe better ways to achieve your goal. If that’s the case, tell us about the bigger picture, not whats on the bench in front of you."
},
{
"post_id": "",
"author": "cyrix2000",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 05, 2022, 08:15:43 am",
"content": "Hi,I need a programmable resistor. I'm trying to replace a 12k NTC for controlling the temperature curve of a heating system. It doesn't need to be mega accurate but being able to replicate the resistance of the equivalent NTC, so that the temperature can be estimated with a deviation of max 5K. I think I'd need to use the Digipot in Rheostat mode for that."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2022, 08:43:34 am",
"content": "Instead of a digital pot simply use a set of CMOS analogue switches and a R 2R ladder network, or just a set of binary resistor values to make a DAC, and as you likely will only be using the range between 10 and 15k you can get by with only having a few values switched, to give low, 3 mid and high temperatures, easy to do with a quad switch, and appropriate resistors being switched in parallel with a 15k resistor."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 05, 2022, 10:40:34 am",
"content": "Check the wiper load impedance. Too low?"
},
{
"post_id": "",
"author": "cyrix2000",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 07, 2022, 08:02:54 pm",
"content": "Unfortunately I need quite a wide resistive range (-20C = ~100k, +20C = ~15k).I have setup my control system now with a digipot and it seems to be working, just needs some fine tuning..."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 07, 2022, 09:03:07 pm",
"content": "Quote from: cyrix2000 on December 02, 2022, 08:02:45 amYou got an incorrect measurement, because the voltage on the digital potentiometer floated outside the power supply rails. All terminals on a digital potentiometer need to be within the power supply rails voltages, otherwise it won't work properly.Quote from: cyrix2000 on December 07, 2022, 08:02:54 pmHow about using a dual channel digital potentiometer? The matching between channels should be very good. One channel could be used as feedback, to calibrate it, with the other being the actual resistance."
}
] |
2025-10-17T17:02:07.647860
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100m-resistor-4th-b-white/
|
100M Resistor 4th B. white. - Page 1
|
[
{
"post_id": "",
"author": "Vtile",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "January 22, 2017, 12:35:57 pm",
"content": "I have this 100Megaohm resistor, deep purple to brownish body. It is 100 megs since it divides 10V to 5V series with my 100Meg Multitester and so says also the colorcode: brown-black-purple-whiteNow what is the White??? I have no source/reference that it even should exist in that place as a 4th band. I'm just curious.. Anyone have any information what is this presumaply nonstandard marking.I have no idea of the age of this as it is salvaged part from random electronics in the past (late 90s when it did end to my box of resistors)."
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 22, 2017, 03:03:54 pm",
"content": "For very high values, which will often be used at high voltages, you don't want a metallic ink like gold or silver, so white is probably used as non-shiny silver.These VR68 high-voltage resistors use yellow instead of goldFrom the datasheethttp://www.vishay.com/docs/28907/vr25vr37vr68.pdfQuote"
},
{
"post_id": "",
"author": "Vtile",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "January 22, 2017, 03:19:06 pm",
"content": "Oh, really nice. Thx.It might indeed be the explanation, since it does have good technical reasoning.The resistor I have also do have this hard enamel shine on it so it might indeed be a highvoltage range. Something over the typical jellybean dip to paint range anyway."
}
] |
2025-10-17T19:04:44.227717
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100ma-500ma-and-900ma-current-availability-indication-without-the-use-of-an-mcu/
|
100ma, 500ma and 900ma current availability indication without the use of an MCU - Page 1
|
[
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 05, 2024, 07:36:29 pm",
"content": "PreambleI have never done any PCB design before and am not an EE. I recently, however, realized that for programming microcontrollers having a debugger would be very handy, and further than that, having a debugger that was isolated would be even more handy to make expensive mistakes, cheap mistakes.As such, I started designing the schematic for a board that I plan to have 2 connectors, one being an upstream facing port and one being a downstream facing port.The setup from upstream to downstream is as follows:Power and USB 2.0 Data come onto the board through the first type C receptacle, only using the D+ and D- lines, pulling the CC lines both to ground with 2 5.1kohm resistors.The power is broken off to power 3 isolated DC to DC power supplies (2 3v3 and 1 5v5) for 3 separate purposes, and the data is passed through an ADUM4166 USB Hi-Speed Isolator.On the other side of the isolation barrier:One 3v3 supply is used to power the ADUM4166 as well as the FT2232HQ and its accessories, IO pins, and indicator lights.One 3v3 supply will be used to potentially power whatever MCU is being tested at that time if it does not have a supply of its own for whatever reason.One 5v5 supply will be used to power a USB Hub controller that will connect to both the FT2232HQ for debugging purposes and the downstream facing type C port to get more utility out of the Isolator as it's rather costly on its own so it makes sense to me to have it also function in a multi-purpose manner.My goal is to make a board for debugging that will allow me to operate carefree, insulated from sloppy mistakes. There are various components not mentioned related to safety such as ESD TVS diodes, etc.RequestMy current request is to find a USB controller that will allow me to be certain that the upstream facing port has access to 500ma or 900ma+.As best I can tell, there are devices that will give me assurance of 1.5A being available using the USB Battery Charging Specification 1.2, which I don't imagine many computer ports would support, but all devices I could find appear to have \"default\" as a rather nebulous option. I believe this to be true because the downstream facing port that this device's upstream facing port is connected to does not need to grant the device access to 500ma or 900ma in the case of USB 3.0+ so when GPIO out pins give me the information that the power draw is \"default\" as far as I understand it, that could mean between 100ma to 900ma.This is an issue because I do not want to overdraw from the downstream-facing port I am connected to, as a core goal of this board is to eliminate worries of mistakes causing an incident to the device that the debugger is attached to, which will be significantly more valuable than the thing being tested. As such, I am hoping to find a solution that conforms to the standard while being able to differentiate between 100ma, 500ma, and 900ma+ being granted to this device. Basically, the most important thing is to conform to the standard at the upstream facing port end. I can deal with any compromise after that if I can get spec compliant assurance that I am good to draw the amount of current I need.In essence, the ideal solution would be a USB hub controller that would always ask for 900ma, failing that, would ask for 500ma, and failing that would let me know not enough power was available, and could give me this information in GPIO form such that adding an MCU to this board would not be required and a simple arrangement of MOSFETs could serve to limit features as to fit within the lower 500ma limit or enable all features if 900ma was available.I realize this is rather specific and this is a bit of a shot in the dark as I've looked through many datasheets at this point, but also acknowledge it is completely possible that I simply misunderstood something about the specifications I was reading.(Kinda blurry image of schematic I've been working on just to show I've done the leg work)Edit:This thread can be closed. Understandably it appears the somewhat niche nature of this question (requiring reasonable knowledge of USB power communications) means it appears unlikely that a productive answer will be found here. I have my own contingency plans and have found further paths to investigate on my own. I may edit this with my solution if I find success for future people searching for a solution to the same problem."
},
{
"post_id": "",
"author": "Swake",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 05, 2024, 08:39:20 pm",
"content": "Do I understand correctly that what you want to do is to protect your computer from whatever wrong move you make on the device you're building?Keep it simple! Here are some possibilities:A/ Use a cheap laptop or thin client like device instead of your expensive computer.B/ Use a ready made USB isolator. These cost only a couple of bucks from the well known Chinese providers. These can't provide a lot of power so you have build in protection from that point of view.C/ Use isolated DC to DC power supply modules. 3 bucks at the same suppliers. Example: B0505SD/ Add a fast fuse in line with the power supply.E/ When you first power up your device do not plug it in a computer but feed it from a USB power supply and measure its consumption using a USB power monitor/meter. FNRSI and Rudeng have nice stuff. After that you can use these devices to continue monitoring and logging power consumption."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 05, 2024, 09:08:21 pm",
"content": "This isn't really an XY problem, I am aware of other solutions. This seems like a good project, its something I want, and much more convenient than the alternatives while forcing me to do fairly complex circuit board design but not too complex for a beginner project (I find it very hard to stick with projects that I feel are just busy body projects/projects that exist solely for the purpose of learning, so I often will go with somewhat ambitious projects that have real payoffs to me as the motivation is really there to finish.More specifically:A) Using a seperate computer is massively inconvenient for programming vs debugging on the computer I'm already coding on. Workflow is massively important for me to complete projects. What might feel like small obstacles to others can often make me lose interest in a project because I simply do not want to do X, Y or Z, or because I'm more risk averse than average.B) Hi-Speed (480mb/s Isolators commercially available are rather expensive anyways, so getting one included for ~30 bucks worth in components to a board I already want seems like good value.C) My design includes Isolated DC to DC supplies. Indeed the one you recommend is pretty much the same as the one I selected except that I opted for an SMD supply due to the potential for easy assembly by a PCB house (I selected the XP Power IES0105S03 and XP Power IES0105S05)D) A Fast fuse does not accomplish what I want. I want to be able to plug this into a PC with full confidence that the device will be within spec. No fast fuse could guarantee this as the 100ma minimum guaranteed current of USB ports is not enough for the FT2232HQ, much less IO.E) This is error prone, does not solve the potential of ac powered devices with different ground plane potentials (Something I've witnessed with janky 3d printers I've worked on) and current is also not guaranteed to stay the same during troubleshooting especially where motors are involved and programming involves issues surrounding troubleshooting movement issues with said motors. This is a common use case I plan to use this device with, using BLDC's in strange ways and other electromechanical projectsIn essence, I am aware that all sorts of janky \"it sorta works\" solutions exist, but I am seeking to create a solution I am comfortable with, doesn't rely on the user being perfect and maintains a workflow that is conducive to me finishing projects and not going \"bah I don't want to set that up right now\". Otherwise I wouldn't have already have put days of work into this. I'm trying to make the product I want to exist and gain knowledge along the way; Teaching myself to fish and catching a big tuna.All that being said, this doesn't mean I am idealistic, I have contingencies such as simply being ok with being limited to ports that support 1.5A or greater, using a separate port for power, and other similar compromises. I made this post though imagining someone with more experience might be able to assist with this particular option."
},
{
"post_id": "",
"author": "JustMeHere",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 05, 2024, 09:49:13 pm",
"content": "Just get a bench power supply with a USB port. If not, make a cable that connects to the binding posts."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 05, 2024, 10:17:51 pm",
"content": "Not sure how this would address the problem Im trying to solve."
},
{
"post_id": "",
"author": "wasedadoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 05, 2024, 10:43:41 pm",
"content": "Just make a simple junction box that takes 5 Volts and ground from an external supply, ground and data lines from a PC and combines them to connect to your device."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 05, 2024, 10:51:39 pm",
"content": "Better yet, use a powered USB 2.0 hub with a floating output PSU on the downstream side of the ADUM4166. Tap in to the hub PSU for device side power to the ADUM4166, and gate power to the hub with a high side load switch controlled by PGOOD so it powers down if the host port is unpowered/disconnected."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 12:16:53 am",
"content": "Hey, I appreciate the side advice/alternatives, but I'm making this with a specific goal in mind. I am well aware of all the little tips and tricks I could use to ignore complexity, but my goal is not to get the simplest solution, Its to get a solution I would be happy with. Please understand that I do have specific goals for this project/board and that my choices are made to align with those goals when it comes to the general setup. The goal is to have something I've created which reasonably suits my my use case. It doesn't have to be perfect, but solutions like simply roughly guessing, or using a secondary power supply aren't really what I'm looking for.I want something I can whip out without hesitation, and which encourages use rather than being a point of contention. The best safety devices are the ones you actually use, and I'm specifically making this because I'm tired of janky solutions to things and want to do things the right way, the spec compliant way. So while I appreciate the effort put in, and can understand why people might assume that I might be taking a harder path as a result of potentially being unaware of shortcuts, I really did research various methods and came to a conclusion on what I really wanted out of the project and the functionality I wanted out of this board. With this in mind, I'm seeking a solution like the one I've described—something that more closely aligns with my goals for this project. I want a device where I can use the device without fear of repercussions and without any friction involved in its use. If people aren't familiar with an option that fills my use cases here, no fowl, no problem, I understand completely and can keep looking on my own. I just hope to steer this conversation more towards a solution to this problem rather than workarounds or ways to avoid solving the problem."
},
{
"post_id": "",
"author": "Andy Chee",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 04:44:21 am",
"content": "Quote from: product_dev_as_a_hobby on January 05, 2024, 07:36:29 pmI'm not sure you understand what GPIO means.No MCU, no GPIO."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 06:36:54 am",
"content": "Im very confident I do. It is the method of output from USB controllers that doesn't involve the typical MCU only protocols such as I2C or SMBUS, instead simply pulling GPIO pins to high or low which could be used to turn functions on or off as well as set configuration settings with simple mosfets or pull-up/pull-down resistors rather than entire MCUs.You will often see it listed on datasheets for USB controller ICs, of which I have looked through many at this point.Example Here:I really do think asking for clarification rather than a confident condescending remark would have been more appropriate for something you weren't familiar with."
},
{
"post_id": "",
"author": "Andy Chee",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 07:10:01 am",
"content": "Quote from: product_dev_as_a_hobby on January 06, 2024, 06:36:54 amThe USB controller itself is a MCU, albeit dedicated to the sole task of negotiating USB connections.(see page 8 of the datasheet, the big green block is an MCU).https://www.ti.com/lit/ds/symlink/tusb320lai.pdfWhatever new version of USB controller you're trying to invent, inevitably your design will require a big green block as well."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 11:01:49 am",
"content": "Quote from: Andy Chee on January 06, 2024, 07:10:01 amThe fact that a USB hub controller contains an MCU is irrelevant to a question looking to interface with a USB hub controller without an MCU. Most complex logic components do and that pretty clearly is not what is being referred to, nor would it fit in a search for one that does not require a seperate MCU to interact with it.To say that looking for a USB hub controller that fits my needs is \"trying to invent\" a USB controller is pretty impossible to take constructively. I have strived for respectful and constructive exchange so having a response so clearly misrepresent technical details of my question is unhelpful and uninviting. I do not wish to dive further into this unhelpful line of conversation with you."
},
{
"post_id": "",
"author": "Andy Chee",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 11:12:38 am",
"content": "Quote from: product_dev_as_a_hobby on January 06, 2024, 11:01:49 amThat is effectively what you're attempting to do isn't it? You're not solely sensing and measuring current, but you're also generating the correct USB signalling protocol to interrogate upstream or inform downstream devices of current availability?If you were just sensing and measuring current, that's a relatively simple task. But if you want any USB signalling, that practically demands a MCU."
},
{
"post_id": "",
"author": "peter-h",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 11:23:30 am",
"content": "Look at the TPS2511. That will give you some info.900mA is what you can draw from a USB3 (yellow plastic insert) PC/laptop port. Normal USB is 500mA. In general, with PC (not laptop) ports you can draw this 900/500mA without any negotiation."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 11:33:09 am",
"content": "Quote from: Andy Chee on January 06, 2024, 11:12:38 amIndeed perhaps there is a misunderstanding here. The example controller I pulled that screenshot from has a table which I believe will aid in getting across what I'm trying to accomplish as it comes close to the functionality that I want, which is what spurs on my belief that there is likely a USB hub controller chip that accomplishes my goals available off of the shelf, just waiting to be found.here in this graph, you can see that with this controller, we get simply high, low output signals which could then by given to mosfets to very simply control our power draw. To truly understand what I am trying achieve would shift where each of these outputs trigger though.Instead of starting at default, we would start at 100ma, the minimum current, the next tier would be 500ma, the standard USB 2.0 current, and then the final stage would be 900ma+ including everything greater than 900ma.In the first stage of this, the hypothetical USB controller I am hoping to find, we would simply remove power from all of our other components, effectively completely turning off our board as there would not be enough power to run even just the FT2232HQ when the output of its GPIO pins are taken into account.For the second stage at 500ma, we would allow the FT2232HQ to turn on, and the doward facing port to be enabled at 100ma draw (as is the bus powered hub standard current output for USB 2.0). This would just barely fit under our 500ma current allowance, but would disallow us from using the DC to DC isolator meant to be used for powering 3v3 devices being tested by the FT2232HQ that do not have their own power source (for example if you had a microcontroller you took out of its environment and away from its power supply to test at the bench, so you would have a convenient source of 3v3 power without needing to whip out cables and your secondary power supply.For the final stage at 900ma+, we would have enough allowance to enable all of the features of the board.Indeed, the problem is this: I have not found a controller that I believe can distinguish between 100ma, 500ma and 900ma allowance via GPIO pins, the preferred method as it does not require the programming and inclusion of a seperate MCU and can be done with a few cents of mosfets and some pull down resistors.My current plan, or rather my contingency upon failing to find assistance in achieving this was to simply accept compromise and require far more power than I need by simply requiring that 1.5A of allowance be present for the board to operate. This would be a significant compromise given that it would exclude many perfectly capable modern ports from being compatible with the device, but it would give me the assurance I need that I would never overdraw from the host computer which is massively important to my goal of making this a hassle free debugging tool where I do not have to rely on myself not making mistakes to keep an expensive device safe, nor do I have to rely on less convenient half solutions Im used to relying on (like ensuring I only troubleshoot with battery power to avoid any potential ground plane differences that I am unaware of for instance).Hopefully I have gotten my goal across more clearly, but if there are still have questions, Im sure I can add more detail."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 11:50:01 am",
"content": "Quote from: Andy Chee on January 06, 2024, 11:12:38 amUnfortunately while definitely somewhat getting at what I am looking for, that is a downward facing port, which means it would be inapplicable for my purposes searching for a USB hub that would give me assurance that I could pull a given current from the host downward facing port of a host computer to the upward facing port on this device/board.It does allow for me to more clearly identify a wish list however. One where I could potentially set the power amounts that the USB hub controller negotiated for. In that event, I would likely be happy enough with being able to set it to negotiate for 900ma, and having it tell me whether or not the request for power was successful or not through a simply hi signal on a gpio pin which would go directly to an enabling mosfet."
},
{
"post_id": "",
"author": "Andy Chee",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 11:50:30 am",
"content": "So it sounds like you want to build a USB hub that's capable of \"load shedding\", load capability dependent on on upstream interrogation, and switching off downstream ports as required?And you want to utilise an existing USB hub controller which hopefully has the correct signalling to switch the ports?"
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 12:17:44 pm",
"content": "Not quite but very close. The port itself would not be responsible for any of the load shedding. Instead, due to the fact that the hub would be communicating through isolation and powered via a 3v3 supply rather than the actual USB supply, the goal would be to use that information through the GPIO pins, to do load shedding through a circuit of my own.The outputs of the isolated DC to DC power supplies for instance, to other components on the board would be disabled via mosfets.The distinction here that matters is that the USB hub controller itself would be distinct to the components that draw power. That is to say that the power would not be going through the USB hub itself (as its isolated) or its power switch, but instead to mosfets that power other parts of the circuit.So for instance, in that middle stage, the GPIO pins would lead to a configuration where the power coming from the primary isolated side's secondary 3v3 rail used for powering microcontrollers would be cut off by a mosfet.In the case of only 100ma, for instance however, only the USB hub controller would continue to receive power, and the rest of the components such as the 5V rail for the USB hub, the 3v3 rail for boards being tested that need a 3v3 vout supply, the 3v3 power to the FT2232HQ and the 5v vout for boards to be tested that need 5v would be cut.This would all be with relatively cheap mosfets based on the GPIO output of the hub, and that is why I am so intent on finding one with GPIO out, and not requiring a secondary MCU. It simplifies the design massively and doesn't require coding to configure each board.In essence, the fact that the hub is isolated means that it can't directly control power and can only indicate what it has successfully requested and been approved to use, and then have other circuits comply with that."
},
{
"post_id": "",
"author": "Swake",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 01:41:47 pm",
"content": "You should not rely on any version of the USB protocol to protect something from happening. It might be possible to implement what you want but that is an out-of-spec use of the protocol and personally I would never want to rely on it because it was never meant to be capable of that.If you want to build something that will be safe to use in a lab context then you must account for that environment yourself. There is only one way to cope with such a harsh environement: total isolation. There is a reason why all those fancy T&M tools from HP; Gossen; Rigol and many more have a galvanic isolation on the communications bus (USB, ETH, RS-xxx; GPIB; etc... ). They all have the equivalent of an MCU on the communications and user interface side (the side that is 'under-control') and they have some equivalent controller on the business side (The side where a surprise event can happen any time), both sides being isolated from each other with opto's or the like.I will write it again: the simplest, don't care and no more worries solution is to use an additional cheap second hand computer. I use an old thin client with a ridiculous cost. No, ones you're setup it does not complicate your workflow in any way. You can solve all that by mounting disks to your 'expensive' workstation over the (wireless) LAN and in my personal case I use remote desktop or a console connection should I nevertheless want to do something on that thin client. Actually it has opened many new possibilities because it is a fully dedicated setup now that is very stable.In your context an MCU is going to be one of your cheapest components. The very capable ESP32-C3 is 1€ and you can find other MCU as low as 10cent. Unless you are going to build millions of devices and the price of the device is sensitive to a couple cents, it is a no brainer decision to include an capable MCU especially if your device is something that will be used to make debugging of firmware/hardware easier, that MCU will bring a lot of capabilities for a ridiculous cost that otherwise would not be possible. Chances are that your potential customers don't care about 5€ more or less but they do about that extra functionality.You still have a 'modern' use case for the FT2232HQ? I'm genuinely curious about what you want to do with it, because I think of it as a legacy interface with old fashioned serial buses. It works perfectly well but is expensive, very expensive."
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 02:17:36 pm",
"content": "Quote from: Swake on January 06, 2024, 01:41:47 pmI think you are misunderstanding a lot of what I am trying to accomplish here. I am trying to get confirmation of what current the USB spec is allowing me to draw, which I will control ourselves to ensure the board is always compliant. I don't really see where you are viewing USB itself as being a protection device anywhere in this plan. USB itself serves as no protection in any of what I've described, in fact a great deal of the board is to protect the Host pc's usb ports/circuitry specifically with the idea that there isnt inherent protection of a level that I am looking for.Quote from: Swake on January 06, 2024, 01:41:47 pmIf you look over my initial post, you'll see that the entire point is complete galvanic isolation, and indeed that is the reason for the 4 main isolating components described, exactly for that purposes. The Hi-speed USB isolator, is the key component of this device, so I am once again confused because that is quite literally what the plan is: To have complete isolation on one side of the board to the other side of the board.Quote from: Swake on January 06, 2024, 01:41:47 pmI feel I have already sufficiently explained why this suggestion is not relevant to my project as what you are suggesting is to simply not do my project and continue to risk hardware rather than build a safety device once that improves my workflow significantly by not simply having to use low quality hardware due to a lack of proper isolation.Quote from: Swake on January 06, 2024, 01:41:47 pmI don't quite think you are understanding the goal or purposes of the device I am aiming to build. The ESP32 would be completely wasted other than to configure USB hub controllers, and would necessitate extra, unnecessary complexity. I have many ESP32s laying around, this isn't like Im not familiar with or am unaware of how mcus work or how cheap they are, it is that Iamand do not want the added complexity, especially when it comes to a device I want to be fairly bullet proof safety wise.I don't have potential customers. Im building something that I want, for me, to improve my workflow.Quote from: Swake on January 06, 2024, 01:41:47 pmThis is the most confusing part of your comment. These are completely inexpensive. They cost at most 7 dollars Canadian. They also have all of the capabilities I care about with regards to debugging such as compatibility with JTAG, SPI, I2C, UART, and SWD (through software) using either open source libraries and software (ex. OpenOCD) or their driver set.They are a perfect fit for my use case, and I can't quite see why I would degrade my experience by having to bit bang the JTAG protocol manually through code as I would need to do with something like an esp32.They have 480mbps bandwidth which is more than enough bandwidth for dual channel communication for any of the specified protocols, have reasonable software support, and deal with all of the GPIO worries and most of the protocols I care about internally with their MPSSE modules.All in all I think there have been a lot of crossed wires here, so let me reiterate:The goal is a debugger board with isolation that allows me to comfortably debug things without adding friction to my workflow in a protected manner.To do this I will be putting a FTDI FT2232HQ behind complete galvanic isolation just as described in my initial post.To power the isolated supplies however, power is required, and that is where this post comes into play, with my seeking to find a method to best identify how much current I can safely pull from the other side of the isolation wall.Just one more time, I want to reiterate, a major part of this boards aims, involve being galvanically isolated, hence so much of my confusion at much of your reply. Hopefully that clears things up."
},
{
"post_id": "",
"author": "coromonadalix",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 06, 2024, 02:41:05 pm",
"content": "@ OP i dont think youll get your answers hereand to control the supply currents like you want is no trivial tasks, even if you say so, not all makers abide by theses rules, and you could be surprisedi simply use an buffered supply and isolated usb hub, and i added a small voltage current monitoring donglesee there : maybe you'll get some ideashttps://www.sealevel.com/product-category/usb-hubs-isolators/usb-hubs/"
},
{
"post_id": "",
"author": "product_dev_as_a_hobby",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 06, 2024, 03:10:24 pm",
"content": "Quote from: coromonadalix on January 06, 2024, 02:41:05 pmYea... I realized that a few comments ago when the only suggestions seemed all roughly to be \"just don't try instead\".TBH I feel massively disappointed. I put so much damn effort into making a good post after reading the rules, getting a feel for the forum, adding information, removing information, getting to just the right length etc. What really killed me though were the weirdly dismissive, hostile and condescending comments. It just stings when you've put in the work just to get slapped in the face because apparently if you don't know the answer you are forced by law or force of nature to comment and deride the op irrelevant to their post.That was a bit of a vent because I'm pretty convinced that like you said, I wont get my answers here.Luckily, I've found a group that is focused on USB, and they seem to have some knowledgeable helpful people where while I haven't found my answers, the replies have all been nice/helpful, so it's not like it was all for nothing even if this post in particular turned out to be a quite frustrating dead end. Heck, one of the guys there actually legitimately works on the standard and is pretty available to answer questions, so if anyone knows, it's probably this guy.Quote from: coromonadalix on January 06, 2024, 02:41:05 pmIt's not actually controlling the current thats the issue, I just want to know what's available at any given time. Controlling the current for the schematic I already have should be relatively trivial with a few mosfets and selectively turning off features.Anyhow, thanks for the suggestion, but even before I posted I had a number of contingencies prepared, one of which is to just use the amp rating that I can be confident in; 1.5A as the bare minimum, which a number of hubs seem capable of giving me in the format I want, which has its downsides of requiring that every port I use with this support that current, but accomplishes what I want. I think I'll wait for the experts in the other group chime in though, as I get the impression Ill make a lot more progress with them as the replies I've already gotten seem far more on target."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2024, 02:08:56 pm",
"content": "Quote from: Swake on January 06, 2024, 01:41:47 pmHow could the USB protocol not support what he is trying to do? Why are there current limits at all, 100ma, 500ma, 900ma, whatever, if they cannot be enumerated by the device?He wants an IC which goes through the USB enumeration process and negotiates the maximum possible current, and reports that. Why would USB have several different current limits at all if this is not possible?I have also looked for this sort of IC for exactly the same purpose, but figured I did not know what to look for because I never found one."
},
{
"post_id": "",
"author": "coromonadalix",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2024, 03:49:09 pm",
"content": "just found this one this morninghttps://www.ti.com/product/TPS2552power-distribution switchesAdjustable Current Limit: 75 mA to 1700 mAand add an mcu to do some usb control for the \"ilim\" pin ??send a pm to the op about this one ...he told me in a pm he would not monitor this thread anymore ..."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2024, 07:27:59 pm",
"content": "But that does not do any part of what the original poster asked.Some battery charger chips do at least some of it.I was reading about USB power enumeration and the device is suppose to present a set of entries to the host, and then the host is suppose to pick the highest current one under USB 1 and USB 2. Normally this would be 100mA and 500mA, but it could also be anything in between and what we really need is a chip which handles the negotiation and returns a signal for 100, 500, 900, 1.5A, 2.1A, whatever.As point out, most devices are just ignoring all of it. Chargers are defaulting to 500 or 900 milliamps no matter what they are plugged into unless they negotiate one of the proprietary charger standards or PD."
},
{
"post_id": "",
"author": "coromonadalix",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2024, 05:58:29 pm",
"content": "while i did understood what the op askedonly thing / explanations so far are :http://dangerousprototypes.com/docs/Designing_USB_Devices_for_proper_current_and_MaxPowerit is the connected device who need to be controlled \"by itself or added circuitry\", not the host by designhttps://electronics.stackexchange.com/questions/5498/how-to-get-more-than-100ma-from-a-usb-porthttps://www.beyondlogic.org/usbnutshell/usb5.shtmlor the attached pdf who explain a few thingsor theses linkshttps://www.infineon.com/dgdl/Infineon-AN2361_USB-Powered_Battery_Charger_for_NiCd_NiMH_Batteries-ApplicationNotes-v06_00-EN.pdf?fileId=8ac78c8c7cdc391c017d072c8b335163https://www.silabs.com/documents/public/application-notes/an0046-efm32-usb-hardware-design-guidelines.pdfhttps://www.infineon.com/dgdl/Infineon-AN2361_USB-Powered_Battery_Charger_for_NiCd_NiMH_Batteries-ApplicationNotes-v06_00-EN.pdf?fileId=8ac78c8c7cdc391c017d072c8b335163yeah i do know its about chargers, but maybe something could be useful in all of this ??"
}
] |
2025-10-17T16:42:28.778435
| 26
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100mhz-lna/
|
100MHz LNA - Page 1
|
[
{
"post_id": "",
"author": "Bidski",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 24, 2015, 07:39:34 am",
"content": "Hi All,I am looking at designing a low noise amplifier for a radio receiver for a university project. The radio needs to operate at around about 100MHz.I have come across a MOSFET cascode LNA circuit that uses a MOSFET current mirror for biasing. I have attached a picture of this circuit.My issues are this, I will need to build the radio that I design and so I am trying to source some low noise MOSFETs that are readily available and I am having trouble finding any. The only ones I can find will take at least a week to ship here. However, I did manage to find some low noise JFETs.My issue now is that I am not sure how to analyse circuits with JFETs in them. Can I just take the circuit that I showed and replace the MOSFETs with JFETs? Or are the other concerns that I need to account for?I have been looking around for information on JFET current mirrors, but so far I have found nothing at all. Is this because JFETs are not well suited to this task?Best RegardsBidski"
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2015, 08:06:00 am",
"content": "Quote from: Bidski on May 24, 2015, 07:39:34 amIn general, no you can't.Before you get to the \"subtle\" parameters, you will need to check the bias conditions, polarity, and enhancement/depletion characteristics."
},
{
"post_id": "",
"author": "VK5RC",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 24, 2015, 08:22:25 am",
"content": "This Ham has some pretty serious lna, a recent 140MHz design is on his websitehttp://www.g4ddk.com/The HP/Agilent /Keysight Application Note on noise factor measurement Y factor etc is pretty good."
},
{
"post_id": "",
"author": "Bidski",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 24, 2015, 08:30:30 am",
"content": "Quote from: tggzzz on May 24, 2015, 08:06:00 amHmmm ok.Does anyone know of some low noise MOSFETs that might be suitable for this circuit?Quote from: VK5RC on May 24, 2015, 08:22:25 amI will have a look. Thank you.Best RegardsBidski"
},
{
"post_id": "",
"author": "German_EE",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2015, 09:39:23 am",
"content": "If you're building something that needs a really low noise figure then pay attention to your power supply. A 78xx regulator isn't good enough as it will introduce additional noise into the circuit and you will get better results using a standard 723 regulator chip. There are of course low noise regulators these days but as your time is limited the 723 is easier to obtain locally. Use lots of decoupling plus maybe a series power choke and build your circuit on a ground plane that is seam soldered to a case all the way around."
},
{
"post_id": "",
"author": "VK5RC",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 24, 2015, 12:24:28 pm",
"content": "I am in the process of trying to bounce a radio signal off the moon EME ( it has been done by many) it needs lots of RF grunt, a really good antenna and a really low noise pre-amp. For this ends I have built and tested one of G4DDKs LNA. I have measured sun noise using it, so it seems to be working OK.It uses the MGF4919 GaaS FET . With quite a bit of trial and error using the Y method and an old HP Noise meter 8970A (with 436A noise source) I got the Noise Factor (at 1296MHz) down to 0.27dB for a gain of about 35dB. Picture below. The FET is mounted up in the air (held up by small inductors) adjacent to the input SMA in the bottom left of the photo."
},
{
"post_id": "",
"author": "f1rmb",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 24, 2015, 12:34:21 pm",
"content": "Use a PGA103, search Google for a publication from F1JKY, you'll find measures, PCB drawing an so on.Cheers."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2015, 03:18:59 pm",
"content": "Quote from: Bidski on May 24, 2015, 07:39:34 amYes but:You need different biasing, which this circuit could stand a change in, anyway.The first transistor is statically biased, \"diode mode\", so that it develops a voltage corresponding to how much Vgs is necessary to draw the applied drain current (from the 1k resistor). This voltage is coupled to the bottom transistor, so that it gets the same Vgs, and give or take variation in Id vs. Vds (shouldn't be much), it will carry the same current (i.e., a MOS current mirror).This works great when the transistors are matched and thermally coupled (as on an IC), but may not work out so well in practice. The transistors at least need to be a matched pair. Since accuracy and power level are not big problems here, thermal matching probably isn't a big deal either (it should be good enough that they're on the same PCB). It's still not the greatest, and wastes a transistor anyway.I'd rather do it by replacing the transistor \"reference\" with a simple voltage divider. This is even worse (there's no reference to Vgs at all!), but we do one better by adding an R||C in the source of the bottom transistor. Vg is set such that it's a bit above Vgs(th), and so load current is drawn, causing voltage drop across the source resistor, which reduces Vgs -- negative feedback sets the bias point. The bypass cap ensures the source still \"looks\" AC-grounded as far as the signal is concerned.The L-C-L network is a big question, of course. If nothing else, that has to be tuned for the operating frequency. It probably also needs to be tuned for the impedance match (the gate has a fairly high impedance, even at RF). You can solve for that, but it requires having S-parameters or admittance data in the transistor's datasheet; and it'll most likely be different in practice anyway, needing adjustment. The gate L and C should be the most important there; the source L seems out of place, and might be intended to be very small (a fraction of the other L), with the purpose of adding negative feedback at AC or something like that.Converting this to JFETs means providing Vgs somewhere between negative and 0V (instead of positive), which would stink for directly grounded source -- but in practice, we simply bias the gate at GND and add enough source resistance to let it self-bias again. It's also acceptable to run a JFET at zero gate bias, at least as long as the input signal isn't too strong. The top transistor should have a voltage divider biasing its gate (with bypass to GND), so its Vg is maybe 20-50% of supply. Source voltage will rise above Vg, so that it again sets Vgs by feedback (but Id is still set by the bottom transistor; it's important that Idss of the top transistor be higher than Id of the bottom transistor).As for \"low noise\", a cascode might not be ideal, because it basically throws away the gain of one of the transistors -- the main advantage to the circuit is nearly eliminating reverse transfer (gain from output to input). When modest gain and absolute lowest noise is required, it might be better to use a single transistor (common-source or -gate). One advantage of a JFET is, the source input impedance (in common-gate) is fairly modest (it's roughly 1/Gm or Rds(on), which for most will be within a small factor of 50 ohms), and it doesn't need any biasing (again, it can be ran at Vgs = 0). Output impedance essentially gives the gain ratio, so a higher impedance load (100s ohms to a few k) is needed to obtain gain. Which means a matching circuit (LC or wideband transformer is fine).BJTs are good too. I forget which (BJT, JFET or MOS) is strictly best at 100MHz -- of course, if you need every last dB of noise factor, you can always go with a GaAsFET or PHEMT. Just be careful to use teensy ferrite beads to prevent it from oscillating at stupid-GHz...Tim"
},
{
"post_id": "",
"author": "Nuno_pt",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 24, 2015, 03:28:32 pm",
"content": "Look at LNA4All from 9Q4 guy,http://lna4all.blogspot.pt/,it's cheap, or look at Sam G4DDK,http://www.g4ddk.com/for VLNA or PGA devices, or look at YU1AW,http://www.qsl.net/yu1aw/LNA/low_noise.htm.Or use some 50Ohm internal match device like PGA103, or PSA and run it on RFSim, then try it with Noise Figure meter like 8970A/B, to see the NF, or make one CANFI,http://www.canfi.eu/very cheap and results are like the best NF meters."
},
{
"post_id": "",
"author": "KJDS",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2015, 05:54:14 pm",
"content": "LNA design is an interesting area.If you design the RF match to get good S11 and S22 as you would when you weren't concerned about noise then the noise figure will be horrible. If you design the input matching circuit for optimum noise figure then the input match will be so horrible that you'll suffer nasty input match, with all the issues that that causes, and if you do either of the above with a modern high gain low noise pHEMT or FET then you'll almost certainly end up with an oscillator rather than an amplifier. Adding some resistance in the output can mean a decent compromise between a good input match for both return loss and noise performance.The reason that the G4DDK LNA has the transistor mounted in the air is to provide source inductance to give stability."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2015, 07:23:15 pm",
"content": "Quote from: KJDS on May 24, 2015, 05:54:14 pmGot any examples? It was my understanding that the two conditions are not typically the same, but that they're close enough (+/- 50%) not to be a problem.Pathological cases like negative feedback pushing around the dynamic impedance doesn't count. (Common base BJTs might be a good example; the emitter is a low impedance to begin with, but a low base impedance combined with stray inductance typically makes it look slightly negative. Simple solution, add a damping resistor, and choose whatever match you like.)Tim"
},
{
"post_id": "",
"author": "Electro Fan",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 25, 2015, 09:55:48 pm",
"content": "Quote from: VK5RC on May 24, 2015, 12:24:28 pmEME! This project idea has captured my imagination - Wow!! I'm going to start a thread (I'll put it in this \"Beginners\" forum since it came up here - although based on some initial reading it doesn't looks real \"beginner.\")Thanks for the idea! EF- After delving into it the post/thread is moved to the Projects, Designs, and Technical Stuff forum:https://www.eevblog.com/forum/projects/eme-earth-moon-earth-communications-48431/"
}
] |
2025-10-17T19:39:57.527406
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100mhz-scope-what-does-it-really-mean/
|
100mhz scope, what does it really mean - Page 1
|
[
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 17, 2013, 05:15:35 pm",
"content": "I was going to watch that scope video, but my system keep hanging. Not sure if it is the net or my machine or youtube itself.I used to think a 100mhz scope means it could display a complete cycle of sine-wave at 100mhz without distortion. The more marketing specs I read, the less sure I am now.A 100mhz scope, what does it really mean? If I want to see a complete sine-wave at 100mhz, what bandwidth do I really need?100mhz is just a number out of the air, could be 10mhz, could be 1khz, or even 50/60hz.ThanksRick"
},
{
"post_id": "",
"author": "Hydrawerk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 17, 2013, 05:37:52 pm",
"content": "100MHz oscilloscope displays a 100MHz sinewave with -3dB less amplitude."
},
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 17, 2013, 11:33:32 pm",
"content": "HydraWerk and Aurora, thanks both. I didn't know that \"without distortion\" is numerically defined as 3db drop. I just recalled it as \"without distortion\" which is rather subjective. 3db - I learn something new today, that makes it a good day. Thanks!Oh, the other good thing is, it looks like my recollection is essentially correct, good to know. Last time I used a scope was over 30 years ago - it was a Tektronix... No digital scopes back then."
},
{
"post_id": "",
"author": "w2aew",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2013, 01:33:46 am",
"content": "It really has nothing to do with distortion, it's simply about frequency response. As the others have stated, it means that a 100MHz sinewave will be no more than 3dB down in amplitude.Is this the video you were trying to watch?"
},
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 18, 2013, 06:44:03 am",
"content": "Quote from: w2aew on April 18, 2013, 01:33:46 amYou are right - your post make me think a bit. I am too analog in my thinking here. Before storage scopes and digital scopes, all the effects you are going to get is in the visual representation of the wave form. So, I \"file it\" in my mind as the visual distortion. At 1g samples per second, a choke point of 100mhz somewhere in the pipeline has different implications than merely visual representation. My mind was locked into merely thinking about the visual representations. Your point is thought provoking. I have to rethink (enough so that I can explain it to myself to make myself understand). I have to rethink digitally.The video I was trying to watch was the \"Intro to Oscilloscope\". This one you are point out is one I should watch also. Once I finish that, I will see if I really understand scope bandwidth.Thanks for pointing it out.Man, how much one can actually forget after 30+ years. Hard to imagine, there was a time when I can grab a bunch of parts and make an 808x CPU work on a breadboard designing it on the fly and program the darn thing with dip-switches.Rick"
},
{
"post_id": "",
"author": "jpb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2013, 08:42:26 am",
"content": "For a general signal containing a mixture of frequencies, the frequency response will give rise to distortion - things like a square wave or a ramp. The better scopes have a smooth roll off with frequency whilst some of the cheaper scopes have peaks and troughs before the 3dB point. There is a thread on this forum where people have plotted their scopes frequency responses (though you need access to the right equipment to measure it accurately).Generally, if you want an accurate representation of an analogue signal I think the rule of thumb is you can go up to around a third of the 3dB bandwidth, so a 100MHz scope allows you to accurately display signals up to 30MHz or so. Of course you'll still see something for signals well above 100MHz.Here is a useful Agilent app note:http://cp.literature.agilent.com/litweb/pdf/5989-5733EN.pdf"
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 18, 2013, 09:38:57 am",
"content": "Having some knowledge of frequency domain representations (eg. Fourier transform) of signals is very helpful here. Square wave for examples have many odd harmonics. A 30 MHz square wave will have the third harmonic at 90 MHz, this will be about -3 dB down, and the fifth at 150 MHz, which will be much more attenuated. So you're essentially making a square wave from just the first and third harmonic. This will be a pretty ugly square wave.One third of the bandwidth sounds very optimistic to me, I'd rather stick to one fifth. This is for a decent visual representation of the signal. Zooming in or using automated measurements in a DSO might require much more bandwidth. Which is why the Agilent document uses rise times, not repetition rates, for digital signals."
},
{
"post_id": "",
"author": "jpb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2013, 09:59:38 am",
"content": "Quote from: alm on April 18, 2013, 09:38:57 amI did say analogue signals, a square wave is probably a digital signal. But yes, 1/3 is probably a minimum. The app note gives a fairly balanced view (though obviously as it is produced by a scope manufacturer it is going to err on the side of higher bandwidth being needed).It depends to some extent what you want to look at. With the 30MHz square wave example, yes it would not give you very accurate rise times and even the shape would be wrong but you would be able to get the duty cycle and the general level of the signal and spot if there was a runt pulse. You'd also be able to estimate the frequency quite well (though counters are quite cheap).The third harmonic would be down by about 26% and the fifth by 44.5% in terms of amplitude but in the harmonic series for a square wave the terms go as 1/n where n is the harmonic so a 26% reduction in the third harmonic corresponds to about 8% overall and a 44.5% in the fifth corresponds to around 9% overall but the two have peaks in different places so the errors wouldn't simply add. The 30MHz square wave wouldn't be that ugly. For a simple Gaussian response (1 pole) the first harmonic would be down 3% which might actually help the shape though it would make the amplitude measurement less accurate.As an experiment I used graph plotting software to plot a square wave up to the 19th harmonic (it got a bit tedious as I was doing it by hand) and then the same 19 harmonics attenuated as if a 30MHz wave on a 100MHz scope (assuming just a simple Gaussian roll off) - here is the graph:"
},
{
"post_id": "",
"author": "w2aew",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2013, 01:30:43 pm",
"content": "If you're interested, I did a video a while back discussing the harmonic content of square waves, including \"building\" a waveform from the harmonic components individually to see how the process works."
},
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 18, 2013, 11:10:27 pm",
"content": "Quote from: alm on April 18, 2013, 09:38:57 amQuote from: w2aew on April 18, 2013, 01:30:43 pmQuote from: jpb on April 18, 2013, 09:59:38 amI sure am interested. I will hit the video over dinner. Yes I am familiar with Fourier Transform. But I need to relearn this. I have post-grad training in Physics (master degree) and I did my share of electronics in my Physics labs. But since graduate school, I have not worked in the industry. I forgot too much.I caught myselfexplaining something wrong to my daughter. It took me a moment to remember some basic things. I don’t have anything specific in mind to look at with a scope per-se. I just want to relearn some of the stuff I forgot.Thanks for your inputs, guys. Most helpful."
}
] |
2025-10-17T20:23:32.772456
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100ur-1w-current-sense-resistor/
|
100uR 1+W current sense resistor - Page 1
|
[
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 09, 2015, 08:56:18 am",
"content": "I'm looking to do some high amperage current measurements (up 100A) with a shunt resistor, any ideas where I can get one. The ones i find don't have great specs often 5% and well over 100ppm. I can easily use a higher wattage value to try and keep in spec.Note: i have tried a current clamp and I'm not happy so don't tell me to use one."
},
{
"post_id": "",
"author": "German_EE",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2015, 09:01:58 am",
"content": "I faced this problem a few months ago. Pull apart an old clock and extract the main spring. Three 5cm lengths of this in parallel clamped at both ends provided about 1,2 mV per amp, you then add a series resistor in your meter lead for calibration to bring this down to a 1 mV per amp ratio."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 09, 2015, 09:05:33 am",
"content": "I'm considering using wire, but I can't calibrate it 5AWG cable has 0.001028R per metre so just under 100mm of that will do it and I can even do a twisted pair to get rid of inductive effects, or maybe a larger guage. But I don't know how accurate AWG wire cross sections are and it may depend on wire coatings etc and of course more heat more resistance as this is at 25C,"
},
{
"post_id": "",
"author": "krish2487",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 09, 2015, 09:08:12 am",
"content": "Try a proper current shunt.There are shunts available from ohmite.0.5% tolerance and 30ppm tempco.Look at the S and SH Series."
},
{
"post_id": "",
"author": "rs20",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2015, 09:11:02 am",
"content": "You shouldn't care about the tolerance at all, you only care about the tempco. You can calibrate any tolerance in the error out trivially (either in software if this is going via software, or with the voltage divider if you absolutely must have the correct analog voltage in-circuit, which I very much doubt you actually need). Dave regularly mentions this in multimeter reviews."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 09, 2015, 09:13:35 am",
"content": "The problem is I have nothing to calibrate with, I have nothing to measure 100A with I can add up both fluctuating current readings from 2 power supplies that I hardly trust.I need ideally to buy something that come warranted to work as mentioned above"
},
{
"post_id": "",
"author": "TMM",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 09, 2015, 09:16:14 am",
"content": "Quote from: Simon on July 09, 2015, 09:13:35 amYou don't need to calibrate it at 100A if you can ignore the self heating effects at 100A.edit: might have been unclear - you can calibrate the resistance of the shunt at a lower current."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 09, 2015, 09:34:20 am",
"content": "Yes i could flow 10A and use my meter as a reference"
},
{
"post_id": "",
"author": "Pillager",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 09, 2015, 10:15:38 am",
"content": "Some of these sound quite promising:http://www.isabellenhuette.de/en/precision-and-power-resistors/products/And Mouser has a nice one:http://www.mouser.at/ProductDetail/Vishay/WBPK600L0A00010001/?qs=kcL3wPdn6%2f2VZ5DGC96cKQ%3d%3d"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 09, 2015, 10:37:39 am",
"content": "hm not for 87 quid, I was hoping some something chuncky rather than surface mount although I suppose i can solder it to copper bar with a hole in for screw terminals."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2015, 10:41:34 am",
"content": "Why are you even considering a resistor?A Hall effect transducer would probably be much more suitable."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 09, 2015, 10:42:29 am",
"content": "hm thats true. I think i have a couple of those from Allegro"
},
{
"post_id": "",
"author": "rs20",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2015, 12:08:56 pm",
"content": "Quote from: Hero999 on July 09, 2015, 10:41:34 amBeware of Hall effect transducers; one that I got is very good at detecting its orientation w.r.t. the Earth's magnetic field (and yes, this is a current-measurement hall effect chip with pins for the current). I don't recommend that part, I was really confused while debugging it until I realised that tilting the device caused massive offsets in the measurement. You *might* get away with using it for AC though, but it's dodgy in my books -- I mean, if it picks up the Earth's magnetic field so well, surely some nearby 100A AC cables will gives if some pretty decent competing fields?My v2 for the same circuit is ditching the hall effect transducer for a uCurrent-style arrangement instead -- ultra small resistance current shunt, with gain after that (I never needed the isolation in the hall effect transducer in the first place)."
},
{
"post_id": "",
"author": "HighVoltage",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 11, 2015, 06:55:48 am",
"content": "May I ask, why you don't want to use a current clamp?The Tektronix A622 (same as Agilent, AEMC and more, rebranded) goes to 100A and is pretty linear and reliable.Otherwise, buy one of these cheap but large resistors from ebay:http://www.ebay.de/itm/Nebenwiderstand-Shunt-100-A-60-mV-Mess-Shunt-zur-Strommessung-/121698634939?pt=LH_DefaultDomain_77&var=&hash=item1c55cdccbbThey are pretty accurate as well and can be re-calibrated at 10A"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 11, 2015, 06:57:04 am",
"content": "I tried a current clamp and was 5A out on 45A. I just don't trust them."
},
{
"post_id": "",
"author": "HighVoltage",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 11, 2015, 07:04:53 am",
"content": "Quote from: Simon on July 11, 2015, 06:57:04 amWhich model of clamp did you use?The resistor in the ebay link I sent earlier will for sure work.I have the same one and used it up to 100A for precision measurements."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "July 11, 2015, 07:09:40 am",
"content": "cant remember, some no name thing, didn't even have a display you have to plug it into a multimeter in mV mode.Mind you it was a motor driver I was measuring so plenty of emf floating around as spikes of 100's of amps get shoved in and out so might upset measurements. partly why i want a resistor and then I'll low pass filter it."
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 11, 2015, 07:46:05 am",
"content": "If you want that much resistance, without extra size and price, the best is to parallel smaller resistors. Now, I'm not talking about just paralleling 10 1mOhm resistor. You should use an amplifier next to each (current sense amlifier with fixed gain), and average the outputs. Use 4 wire resistors, a nice amp like INA199, 4-5 shunt each 1mOhm. It is not 100uR, but you dont really need that low, as all the cable and connection losses will be a lot already."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 11, 2015, 07:50:59 am",
"content": "Quote from: Simon on July 11, 2015, 06:57:04 amDid you zero it first?And this may seem silly but many current clams are current transformers and only measure AC: are you sure it was a Hall effect sensor, designed for DC use?"
}
] |
2025-10-17T19:37:30.213181
| 19
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100v-dc-10-amps-regulated-power-supply/
|
100V DC @ 10 Amps regulated power supply? - Page 1
|
[
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "October 16, 2015, 10:35:21 pm",
"content": "Self build or commercial, what are my options? Currently struggling with a toroidal transformer and a full wave bridge, unregulated. Voltage drops to circa 65 / 70V DC under load. Would prefer to steer away from a SMPS, especially self built, too complex. Thanks. Mains available here is 230V AC, 50Hz, about 60 Amps"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 16, 2015, 11:21:43 pm",
"content": "if it drops to 65V under load your transformer AC output voltage is too low for 100VDC.The problem with regulation at this current and voltage difference is you either have a massive heatsink or go switchmode. Your looking at 40-50V difference between noload and fullload DC output which is 50V*10A = 500WThere are a few more specialized options, such as a servo controlled variac with feedback from the DC output after the bridge. But this is obviously slow to respond so is only useful in limited situations.Best option is to just look for something on ebay. Or perhaps multiple units that can be wired in series to give you 100V. (Since 100V isnt going to be very common for a single unit) Two 48V 10A units might be easier to find and could be tweaked to output 50V easy enough with some understanding of how switchmode psu feedback works."
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 16, 2015, 11:34:09 pm",
"content": "I'm not saying you should get this, i cant figure out if its compatible with being wired in series but.. Two these might work and would be under US$100http://www.aliexpress.com/item/led-power-supply-switch-600W-48v-12-5A-ac-dc-converter-Input-220V-S-600w-48v/2026109253.html?ws_ab_test=searchweb201556_7,searchweb201527_2_71_72_73_74_75,searchweb201560_4I'm pretty sure this will have a pot to make tweaking the output to 50V dead simple.Cheaper onehttp://www.aliexpress.com/item/New-model-48V-10A-480W-Switching-Power-Supply-Driver-for-LED-Strip-AC-100-240V-Input/32345061556.html?ws_ab_test=searchweb201556_7,searchweb201527_2_71_72_73_74_75,searchweb201560_4Of course this is relatively cheap china stuff, so quality is a bit unpredictable."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 17, 2015, 07:40:58 am",
"content": "Quote from: AcHmed99 on October 16, 2015, 11:27:51 pmNo here in the UK we are terribly good at taking a source of heat, wastefully turning it into electricity by burning it miles away and loosing 60+% of it's heating power, then channaling it all the way to our homes so that we can use electricity to..... make heatMany houses still have electric cookers and heating, these may be deemed to be safer for elderly people etc but many of us are now on gas."
}
] |
2025-10-17T19:31:52.921722
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100vac-smps-on-120vac/
|
100VAC SMPS on 120VAC - Page 1
|
[
{
"post_id": "",
"author": "Mikek400",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 17, 2015, 05:31:36 am",
"content": "I have a SMPS that is rated for 100VAC 50/60HzI find it suspicious that it has such a narrow operating voltage considering they usually operate over a wide voltage range. I doesn't specifiy any kind of operating voltage window as a normal SMPS would such as 100-127VAC.I would like to operate it on 120VAC but want to know what you think about the impact of doing so. I relatively sure that plugging it into 120V wont release the magic smoke right away, but was wondering how sensitive SMPS are to voltage input. Are there any components I should be looking at to be sure its not overheating or check to be sure its not drawing too much current?The power supply is integrated and potted into the device I want to use, so the only other way to power the unit would be to build a buck transformer. It is low enough wattage to do so, but why bother if the SMPS can handle the voltage.Any thoughts?UPDATE========Since I didn't have any replies and was asking while I was work, now I am at home and tried out hooking it up to 120v via a step up transformer. It uses very slightly less current at 120v instead of 100v. drawing .021A at 120v .022A at 100v.I won't know exactly how much power it uses at operating current until I get it back to the US and try it out. But looking at the standby current it uses looks ok.Main filter cap rated for 180v so looks like it should be ok. Will see when I get it back to the us and can try it out on 60hz power but it is rated for 50/60Hz operation.If anyone knows anything I should look out for, please pass the info on."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2015, 05:46:46 pm",
"content": "It will work but a 180V filter capacitor means a maximum voltage rating of 128VAC so running it at or near that voltage will shorten its life.It sounds like it's a cheap, poorly designed PSU. Ideally the capacitor ideally should be rated to 200V or more, to give plenty of safety margin."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2015, 06:38:38 pm",
"content": "How much is the device worth and how difficult will it be to replace once you are back stateside?From your measurements, you could buck the voltage with a 1VA transformer, with an 18 or 20V secondary which woud be approximatelt a 1 1/4\" cube. Depending on clearances etc. that might even fit inside."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2015, 09:09:36 pm",
"content": "Well, I've seen 160VDC caps in 120V equipment forever, so I doubt it's a big deal...It might not be rated for other voltages simply because it wasn't tested for sale in those markets. Dunno. There *might* be concerns like, not passing other FCC/CE regulations (EMC or safety) that are coincident with those regions, but those should be apparent from the lack of respective agency symbols on the equipment.Tim"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 18, 2015, 11:45:41 am",
"content": "Quote from: T3sl4co1l on December 17, 2015, 09:09:36 pmWas it decent branded equipment?Running a 160V capacitor at nearly 170V (more if the mains is on the high side of its tolerance) is asking for trouble and certainly isn't going to do anything for reliability."
},
{
"post_id": "",
"author": "Mikek400",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 18, 2015, 03:35:43 pm",
"content": "Actually its a tankless LP gas hot water heater.Came across it cheap and have space in my bag.It uses 150W max I think but really cant check much until its actually hooked up and working.Has Nichicon 105c caps inside it and looks to be built ok.Found a spec sheet for the unit.. Lists minimum voltage as 90V and max as 110.. Hmm.Voltage back home is usually from about 118 to 124v.Purely out of curiosity I would like to see the us version of this unit to compare the boards.For anyone who is curious about this board here are some pics.https://drive.google.com/open?id=0B7ll7KI4S3PNOUhqdDlfYUc4ZHpjSUhjUmpaUWNVMU9yeFBjhttps://drive.google.com/open?id=0B7ll7KI4S3PNRHNkNXNWemJDWFdiRkJadmhsWU1VSXZRNjZnhttps://drive.google.com/open?id=0B7ll7KI4S3PNRHNkNXNWemJDWFdiRkJadmhsWU1VSXZRNjZnhttps://drive.google.com/open?id=0B7ll7KI4S3PNenRNMTM5WHJxWndYeFZBT29wXzFtSjdiNVZzhttps://drive.google.com/open?id=0B7ll7KI4S3PNSzRac3luMU5hWDdyNGQwekstN2FEai1nSW5zAbout the EMF / Safety certifications, they make a very similar model which they sell in the US I believe, but this one doesn't have any markings for safety agencies in the US. Purely out of curiosity I would like to see the US model and compare the boards."
},
{
"post_id": "",
"author": "Mikek400",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 18, 2015, 04:43:09 pm",
"content": "Seems that you guys think I should probably run it at its designed voltage.How is the best way of getting lets say 200W at 100V from 120V. I made a small 120v boost transformer here for testing things from a 100=>20V 2A wall wart. But I question the safety of leaving a transformer hooked up with its secondary powered at 120v. Are there any safety issues I should be worried about? Am I just paranoid? I would think that the enamel on the secondary is only insulated for low voltage."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 19, 2015, 01:09:07 am",
"content": "Quote from: Hero999 on December 18, 2015, 11:45:41 amThink they were pulled from stuff like CRT TVs.Really, electrolytics don't mind a little overvoltage, as long as it's applied gradually. But long life, no, I wouldn't expect that from those things either.Tim"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 19, 2015, 01:51:31 am",
"content": "A high bus voltage will also overstress the magnetics, which will have been designed with minimum core area and turns count to save materials, and likely the switching semiconductor(s) as well.Quote from: Mikek400 on December 18, 2015, 04:43:09 pmI wouldn't care to run a cheap bare transformer with a metal bracket holding the core down as a buck or boost transformer, unless the secondary was on an insulating plastic bobbin, but a high quality split bobbin transformer, a fully potted PCB mount transformer or a fully insulated toroidal transformer will be fine."
}
] |
2025-10-17T19:28:24.812359
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100w-constant-current-load-to-test-my-power-supply/
|
100W constant current load to test my power supply - Page 1
|
[
{
"post_id": "",
"author": "Spikee",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "August 13, 2012, 03:16:43 pm",
"content": "My new powersupply will arrive in a few days (ELV.de pps5330)http://www.elv.de/prozessor-netzteil-pps-5330-komplettbausatz.htmlAnd to test it and compare it to my own noobish power supply i want to build a constant current load that is capable of 100w (30V 3A) .The heatsink i will use is 0.4 c /w (has small fan on it).So here is the first attempt:https://docs.google.com/open?id=0BwczAtgmsNqIakhQeW5PN05MQmcI just used the lm324n because i have them at home , but this is probably not the ideal opamp .But i was not sure which other one is better. I also have the TI OPA2336 opamp wit rail to rail output capability.The current readout is not added yet ...What i want it to be capable of:100W dummy loadso i can test my 30V 3A power supply and my diy power supplies.Thanks to everyone that will help =) .Trying to do an ltspice simulation now ..."
},
{
"post_id": "",
"author": "kripton2035",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 13, 2012, 03:31:43 pm",
"content": "this is an old elv kit for a 100w dummy load model EL7000.good readings !"
},
{
"post_id": "",
"author": "Spikee",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "August 13, 2012, 03:48:38 pm",
"content": "It's kinda the same principle.But its hard to read technical German"
},
{
"post_id": "",
"author": "T4P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 13, 2012, 03:54:59 pm",
"content": "Low offset opamp. That's the sort of opamp you needalso a chopper amp would be good"
},
{
"post_id": "",
"author": "Spikee",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "August 13, 2012, 04:03:30 pm",
"content": "so the OPA4251 would be good ?http://www.ti.com/product/opa4251"
}
] |
2025-10-17T20:31:35.812397
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/100watt-400-watt-transistor-to-drive-dc-motor/
|
100watt- 400 watt transistor to drive dc motor - Page 1
|
[
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 04:19:48 pm",
"content": "I cant seem to find one of these things.What do they look like and how big are they?"
},
{
"post_id": "",
"author": "andy3055",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 04:28:05 pm",
"content": "One would use thyristors at those high voltages to drive heavy current loads such as motors.Years back I worked at a plywood plant in Fiji and that is what was used. Manufacturers like ABB/Siemens specialize in those thyristor drives."
},
{
"post_id": "",
"author": "StillTrying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 04:39:40 pm",
"content": "If it's just for on and off switching of the motor the idea is to dissipate nearly all of the power in the motor and not the switch.The motor's start up current is probably the most important to know."
},
{
"post_id": "",
"author": "madires",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 04:59:45 pm",
"content": "It would help if you tell us more about your project. What is voltage of the DC motor? How do you want to drive it? Simple on/off, H bridge, or whatever? What about the driving signal?"
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 05:12:24 pm",
"content": "Thanks for the help.Its just all on all off Left Right control.I want to switch it with an ldr (cause im going to commune with it through the screen of a laptop) , and its only a pretty small motor, only 100 watts will ever get to the motor,but i need 4 times that much to go through the transistor, cause my circuit is a little unorthodox. (but its like a h-bridge, but it has a constant back return)So when the transistor is on, im going right through the motor, when its off ive got another connection to battery that auto-returns it left.Doing it this way is not as good, but I only need 1 transistor per dimension. (and its a robot so its got tonnes of these) And it might get expensive 4 trannies per hinge.I wish I could just use the ldrs as a variable resistor but id need about 20 per dimension because theyd get so hot and they are too resistive, and transistors im guessing would be alot cheaper.Unorthodox 1 switch h-bridge->Ive tested the circuit, (only with resistors, and just a wire for the transistor) and its working fine, it has to decellerate before it goes in the opposite direction, and it goes a little faster in one direction than the other - and I lose power down the ungated pathways, so i get about half strength, and because it working back against itself its a quarter - but I think this wont come out of the battery so I should be ok in that regard.The transistor would go where the \"Left Right\" switch is."
},
{
"post_id": "",
"author": "madires",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 05:52:11 pm",
"content": "Battery voltage? Motor voltage?"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 05:59:53 pm",
"content": "If you're dissipating 400W in the transistors to control a 100W motor then you're doing it wrong. Re-think the whole approach, motor control is a very mature field, your problem has been solved before by somebody."
},
{
"post_id": "",
"author": "schmitt trigger",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 06:05:55 pm",
"content": "Un orthodox bridge, indeed!Have you taken into account all the wasted energy through the resistors?"
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 06:06:35 pm",
"content": "So is the difference between 400 watts and 100 watts significant?I dont even know what the dimensions of a transistor I need for it.In this video - do you think its running the motor off the 9v battery? Cause its going faster than mine with the 90 watt power supply cranked full.If this is sounding illogical, I know what you mean, Im not sure whats going on myself...I might have some problems getting my bot off the floor...Yes theres wasted energy through those 2 junctions through the resistors to negative, I have them at 10 ohm, but maybe 3 ohm would work (less resistance = more power) because the motor would only be about 2-3 ohm - and i need to make the loss 50/50 to fit my idea.Ive got my power supply cranked full, and its a pretty small motor, im definitely overpowering it if it was getting full power (but it actually isnt getting that much across the bridge.), but im not really sure what its rating is. My resistors are getting really hot, and they are rated at 10watts. I can only have it on a little at a time, but I can get bigger resistors if I want any time.If my calculations are correct its about 25 watts going to the motor. but its going slowish - and is 25 watts too much for going slow? I could do a video of it, if it helps."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 06:09:30 pm",
"content": "Quote from: krayvonk on March 29, 2020, 06:06:35 pmThe actual numbers are irrelevant, the fact that you're wanting to burn up 4 times as much power in the transistors as gets to the motor is very significant. You should aim for something like 5% losses, not 400% losses.SCRs (thyristors) were used to control motors back in the 1970s and into the 80s but they have been obsolete for a long time, now MOSFETs are used almost exclusively."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 06:22:53 pm",
"content": "Its actually only 50% wastage of the battery, But because its on a \"spring\" It divides the power to the motor by 2 again, because it needs a left direction and a right direction."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 06:45:39 pm",
"content": "heres a vid of it going. (I kept my mouth shut.) its a 90watt power supply and it was on halfway exact. and I had to bodge resistors I had on, so they arent exact omages, but its actually biased in one way even if you get them right cause of load differences."
},
{
"post_id": "",
"author": "schmitt trigger",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 06:47:35 pm",
"content": "Quote from: krayvonk on March 29, 2020, 06:06:35 pmThat is a direct consequence of a completely incorrect way of controlling a DC motor.James-s is a very knowledgeable and helpful member. Heed its advice: re-think your approach."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 06:53:20 pm",
"content": "haha np.I do get to purchase 4 times less transistors for my 4 times less power tho!"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 08:59:57 pm",
"content": "Wait, are we talking just a dinky little toy motor? 100W is quite a lot of power, at 9V that would be over 11 amps, obviously not doable with a little 9V battery, you might find a motor that powerful in something like a cordless drill. Those little permanent magnet motors used in a lot of toys are maybe 5W max, typically quite a lot less. You should be able to easily control one with an H-bridge made of something cheap and easily available like BD139/BD140 or some small power mosfets. There are also integrated H-bridge ICs specifically designed for controlling motors. I've used one made by TI, I don't recall offhand which specific part it was though."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 09:07:11 pm",
"content": "Thanks for those component codes.Thats exactly what I want! -THANKS!!!How come my motors arent frying?? Ive had them on 100% power for ages and ive only ever cooked one of them, and it seemingly happened at random, the rest seem to take it fine.I know that the amps and volts get better efficiency at a certain setting due to the topology of the motor, but im not experienced and ive just been putting them on max power. (I plugged a drill into my PS once, and it acted funny and someone told me its because it was some limiter it had.)Maybe ive got some magic spell on my motors that dont let them blow up or something, but how the hell am I supposed to work things out with miracles every where..."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 09:15:18 pm",
"content": "I have no idea since you have not told us what power supply you are using or what specific motors you are using. Permanent magnet DC motors can operate over a very wide voltage range, one rated for 12V for example will usually run on 3V or less and will typically tolerate at least 24V without burning up. The current depends greatly on the mechanical load, if you load down the motor and try to run it at higher than rated voltage it will deliver more than the rated torque while drawing more than the rated current and if you run it hard enough long enough it will burn up.There's no magic, it's just physics."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 09:26:04 pm",
"content": "So im pretty much strangling the little motors, and I should upgrade to something like this right ->https://www.motiondynamics.com.au/united-my6812-12v-dc-100w-2750-rpm-electric-motor.htmlExcept, my power supply is 30v 3amp.... so I know what I have to do, I NEED AMPS NOT VOLTS!!! I have to change my powersupply, plus I need a different transistor...Maybe something like this for the power supply.https://www.jameco.com/z/MDR-100-12-MEAN-WELL-AC-to-DC-DIN-Rail-Power-Supply-12-Volt-7-5-Amp-90-Watt_1943481.htmlAnd this for the transistor.https://au.element14.com/on-semiconductor/rfp12n10l/transistor-mosfet-n-100v-12a-to/dp/1017795?gclid=Cj0KCQjwjoH0BRD6ARIsAEWO9DuvxDkf3X78H0n2Lr6eX4DAWgTFNokJOJ3l3c3XiFUC16fB-b9gKzAaApOlEALw_wcB&mckv=s_dc|pcrid|380892800521|pkw||pmt||slid||product|1017795|pgrid|76493923343|ptaid|aud-435654578090:pla-841876761010|&CMP=KNC-GAU-GEN-SHOPPING-TEST-NEWI cant believe transistors are so cheap, they are like chips.And now we are getting dangerous. So I better be careful."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 09:37:19 pm",
"content": "Is this even a serious thread or are you just trolling? What you're saying makes no sense at all, I'm out."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 10:24:09 pm",
"content": "Im a total n00b mate. If this seems completely illogical, I am NOT doing it on purpose!!! just trust me, ill get to average eventually. i promise.I just plugged in a transistor for the first time Just then (I just added it to the circuit), I got it working, but it amplified *less than I thought* So i boosted up the base contrast a little more and it ran.THATS THE FIRST TIME IVE EVER USED ONE. Ive learnt everything backwards order, I never went to uni, and in electronics class I was only a teenager so I thought it was more cool to not listen to the teacher.Im amazed by simple crap that you would never even dream of being impressive at all. Im a literal joke in your eyes.But. my robot is soon on the way! And im planning on starting a CPU company would you believe.I know its all easy crap in the end as well, thats the one thing I know that isnt a joke. But... Im not there yet...FIX...Ok thats it for the thread. THANKS EVERYONE FOR THE HELP!!!"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 10:44:01 pm",
"content": "the motor you showed in video is around 12-20W, 60W at best during stall. the diagram above is the worst way i've seen to drive a motor direction. what you are doing is shorting your psu with 3+6 = 9 ohm on the right, 12 ohm on the left, this result in tremendous wasted power. its a good coffee heater though in a cup. try google h-bridge motor control."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 29, 2020, 10:48:42 pm",
"content": "half goes in the motor, half is wasted. its only half. woops, its actually 2/3 if the resistance is 3 ohms matching the motor, but if its 10ohms its only a little more than half wasted If transistors were more expensive, it would be more worthwhile to use it, but since they cost very little, its probably not a good idea."
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 11:33:55 pm",
"content": "dont just try to invent things. people have done > 80% efficiency (8/10 to the motor) many millenia ago, today people can do almost 100% efficiency. but if you insist on your way, who am i to object? so may i suggest this maybe a good option for you as a start... to power your 10W motor...https://www.alibaba.com/product-detail/10KW-10000W-dc-regulated-power-supply_2006541291.html?spm=a2700.7724857.normalList.50.5bfb1e79hZJF1ohttps://www.alibaba.com/product-detail/Fixed-Painted-Wave-wire-Wound-Power_60813487562.html?spm=a2700.7724857.normalList.12.706d6112H5MlHm&s=p"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 29, 2020, 11:51:49 pm",
"content": "Quote from: james_s on March 29, 2020, 09:37:19 pmwhat he's trying to build is a high powered wheatstone bridge. by adjusting resistance in one arm of the bridge, reverse polarity voltage is achieved, hence reversed motor direction. but instead of a voltmeter, he put a motor in the middle to change direction, now he's planning to put a bigger motor and his problem is, he'll need to reduce resistance in every wheatstone bridge's arm to get a usable power to the motor for rotation... he made perfectly sense, just not that practical... in todays term, we call that a joke, no offense"
},
{
"post_id": "",
"author": "wizard69",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 12:57:20 am",
"content": "As others have already said you need to rethink things here. There are dozens, probably several hundred, types of low voltage DC motor driver IC's out there. Some are for the automotive market and others more general, in one chip you get your entire motor control circuit.Less thn 10 seocnds on Google, searching for \"DC Motor Control IC\", turned up this:https://media.digikey.com/pdf/Data%20Sheets/Infineon%20PDFs/TLE84106EL.pdfwhich gives you 6 channels in one IC. By the way this isn't a recommendation at all because Infineon's data sheets leave a lot to be desired. Rather it it the very first chip that my search turned up."
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 01:10:56 am",
"content": "assuming your current knowledge, i will do this (attached) when i was a kid, this is my \"invention\" called \"dpdt bridge\"no bodged power resistors mess, no transistor and math headache, and the cheapest and most efficient possible solution."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 30, 2020, 01:23:51 am",
"content": "Thats excellent thanks. I bet that operates at the full power of the battery!When does what we do get into the stage of \"impressing others\" instead of making you look like a lunatic on the internet?"
},
{
"post_id": "",
"author": "ratatax",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 01:30:07 am",
"content": "i think what you are searching for is:"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 01:38:24 am",
"content": "Quote from: krayvonk on March 30, 2020, 01:23:51 amyes thats the idea when driving a motor, power needed is what power given (to the motor, not to the power resistors). want slower motor? use smaller voltage battery like 1.5V AA. another solution is $1 buck converter from china. but if you insist well, i've given you the other solutions much earlier."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 30, 2020, 01:40:04 am",
"content": "NEEDZ MOR RESISTAHZ!"
},
{
"post_id": "",
"author": "gcewing",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 01:58:43 am",
"content": "Quote from: krayvonk on March 29, 2020, 06:06:35 pmThe difference is 300 watts -- that's a serious amount of power!You don't seem to have much of a feel for what these numbers mean, so to put it in perspective, here's something that dissipates 500 watts:http://www.goldair.co.nz/product-catalogue/heating/panel-heaters/gph150-500w-mechanical-panel-heaterAnd you're thinking of wasting this kind of power foreach axisof your robot. If your robot has 3 axes, that's getting on for 1000W -- enough to heat your living room in winter!Do you see how impractical the idea is now?As you've found, transistors are cheap. 300W power resistors, by comparison, are not cheap -- Mouser is listing them for around $30 each, and that doesn't include all the heatsinks, fans etc. you would need to get rid of the waste heat.Just use a 4-transistor H-bridge, or a chip made for the purpose. It's the only sane thing to do."
},
{
"post_id": "",
"author": "HackedFridgeMagnet",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 02:17:34 am",
"content": "Here I found a 400W transistor for you.Guys just answer his question, no need to overthink this."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 30, 2020, 02:39:06 am",
"content": "Thanks gcewing for the info. (Yes I am way out of whack still, I need to take in more information.)$30? Thats more like it, all the transistors I was looking at were cheaper than the photo resistors! It was a little illogical seeming.Base in the middle is the only way to do it."
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 03:11:28 am",
"content": "haha thats a nice trick! TO-18 can for 400W, you'll need to buy 10 of them until you figure out the truth. but then (if it is), you are going to need 500W PSU, my earlier link will cost you $1000 china brand. here's better deal i just remember i built (invent?) a \"h-bridge esc\" a while a go for my rc project, made the pcb but have not assemble and program it since i put rc project on hold. its designed to accept PPM or PWM signal and also from potentiometer, to control both directions and speed. in the rc market this kind of board only can control bldc 3 wire motor, and only PPM signal from radio receiver, where my board can use normal 2 wired brushed motor controlled from either 3 types of signal. for your project i guess potentiometer will be a convenient one. if you want i can assemble, program and sell to you at $60, no need upgrade psu, no need to buy even 2pcs 2N2906 to find out that you will be left with nothing. your 30V 3A PSU can make your 100W motor jump across room if you want or if not careful, and can be as slow as snail controlled with potentiometer, 80% efficiency guaranteed. with 2 pairs of IRF3205 and IRF4905 combo in the bridge, it can drive up to 1000W motor theoritically. just upgrade to 1KW PSU and start killing living things if you want to, cheers"
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 30, 2020, 07:39:50 am",
"content": "I dont need a 500 watt psu if i can just put a couple of wires in the wall socket. (+ and -) and I dont even need to wire up an oscillator either!Wow man, you know alot. Did you draw that whole schemmy up for me? Very nice. (I actually like it alot, I wish ppl would show work here more often, is it uncool?)The $60 offer is nice, for my project ill at least be spending about $100 on my components, But it just doesnt seem honest if I dont do the hard work myself.And... Whats everyone got against potentiometres! arent they as good as a relay if u glue them to a dc motor?"
},
{
"post_id": "",
"author": "TheHolyHorse",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 02:46:46 pm",
"content": "Quote from: krayvonk on March 30, 2020, 07:39:50 amIf you're actually considering putting some wires in the mains outlet, please don't for your own and everyone else's safety.I'd suggest you start over from the beginning, forget everything you know about electronics and get someone to teach you and actually listen."
},
{
"post_id": "",
"author": "atmfjstc",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 03:24:53 pm",
"content": "There is NO WAY this guy isn't trolling. The only other possible explanation for his style is if he were a 13 year old kid - but his Youtube channel disproves that."
},
{
"post_id": "",
"author": "TheHolyHorse",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 04:17:04 pm",
"content": "Quote from: atmfjstc on March 30, 2020, 03:24:53 pmI wouldn't be so sure, he seems dead serious. Not everyone is meant for electronics and some should outride stay away from it. That's just how it is."
},
{
"post_id": "",
"author": "krayvonk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 30, 2020, 04:21:55 pm",
"content": "I agree with you. Maybe I should just stick to raytracing, newton physics engines and artificial intelligence on the gpu... and never bother making a computer, cause its just too hard... assembler is just gobblegook better stick with high level its much easier, and get back into the kitchen where i belong."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 10:11:29 pm",
"content": "Quote from: krayvonk on March 29, 2020, 10:48:42 pmA linear power supply controlling a load will dissipate half the power, but that's only when half the voltage is being dropped across the load.Consider a 1 Ohm resistor connected to a 10V power supply. The maximum power dissipation will be P = 102/R = 100/1 = 100W. If a resistor is connected in series with the load to control the power level. Say we select a resistor value to sweep the voltage across the load between near 0V and 10V. We can't go all the way to zero or 10V, because it would involve a resistor value with zero or infinite resistance, which is impossible and will give a division by zero error. The plot shows the maximum power dissipation in the series resistor is only 25W.Note how the power in the load shows a square relationship with the voltage. The maximum power dissipated in Rs is a quarter of the maximum power dissipated in the load.linear PSU power dissipation.asc(0.74 kB - downloaded 39 times.)"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 30, 2020, 10:57:26 pm",
"content": "Quote from: atmfjstc on March 30, 2020, 03:24:53 pmNO. this guy reminds me of my younger brother. this type of guys is for real... if you have family of this type, you'll understand when they stated...Quote from: krayvonk on March 29, 2020, 10:24:09 pmi guess they got sucked by a mentality/propaganda/idea that skills is more important than knowledge/academic. the good thing is he got some balls in trying electronics, better than be on the street."
},
{
"post_id": "",
"author": "Ice-Tea",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 02, 2020, 08:12:05 pm",
"content": "Quote from: krayvonk on March 30, 2020, 07:39:50 amFeel free to ignore everything everyone is saying *except* for this: don't jam wires into the wall socket. Just... don't."
}
] |
2025-10-17T17:52:51.790565
| 42
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1013d-oscilloscope-311021/
|
1013d oscilloscope - Page 1
|
[
{
"post_id": "",
"author": "Mal",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "February 04, 2022, 02:03:21 pm",
"content": "hi everyone, i have a 1013d oscilloscope, the inner screen is broken, ive looked everywhere for a replacment but could not find one. the manufacturer fnirsi wont help at al . is there anyone who has replaced a screen in one of these that could proide me with a screen number, the number on the screen back is hz-tft070ie001 is there an equivalent screen to the one thats in it. any replies i will be grateful for it"
},
{
"post_id": "",
"author": "bob91343",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 04, 2022, 05:18:49 pm",
"content": "What is a 1013d oscilloscope?"
},
{
"post_id": "",
"author": "tunk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 04, 2022, 05:50:32 pm",
"content": "You did get a reply from one of your other posts - did you look into that?Maybe you could take it apart and post some photos?"
},
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 06, 2022, 04:19:41 am",
"content": "Quote from: bob91343 on February 04, 2022, 05:18:49 pmIt's a tablet style scope made by FNIRSI:http://www.fnirsi.cn/productinfo/419011.htmlYou'll find quite a bit of discussion about it on the forum here."
},
{
"post_id": "",
"author": "bob91343",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 06, 2022, 04:36:45 am",
"content": "Thank you for the clarification. However, I read this:"
},
{
"post_id": "",
"author": "Mal",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "February 06, 2022, 05:42:57 pm",
"content": "i have emailed them so i will see what they say ,thankyou for the info"
}
] |
2025-10-17T17:15:29.537379
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/105-smd-resistor-tolerance/
|
105 SMD resistor tolerance - Page 1
|
[
{
"post_id": "",
"author": "Agony",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 12, 2013, 07:51:27 pm",
"content": "so i \"salvaged\" a led ring/strip and looked at the resistors.There are some 105-s, that look like 0.06W range, really tiny.measured i get 720-730k ohms.105 is rated at 1M ohm.is that huge tolerance normal? thats around 27% less."
},
{
"post_id": "",
"author": "David_AVD",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 12, 2013, 09:29:18 pm",
"content": "Maybe you fried them during removal?"
},
{
"post_id": "",
"author": "Agony",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 12, 2013, 11:25:15 pm",
"content": "didnt remove them, in circuit testing. .. too small to even bother removing.https://www.circuitlab.com/circuit/fhp5xv/led-ring/"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 12, 2013, 11:33:58 pm",
"content": "They probably are 1M but other components in the circuit are skewing the measurement.Or maybe your DMM is a cheapish brand and has a flat battery (cheap meters read wrong when getting flat)Most likely the former."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 12, 2013, 11:34:45 pm",
"content": "No, but if you look at your schematic, you've got resistances in parallel, and if you're trying to measure those 105 resistors in circuit, assuming all of those resistors are actually 1M and they are right on the mark for tolerance, you should read about 750K. Factor in a bit of tolerance, and 720K-730K isn't that far out."
},
{
"post_id": "",
"author": "Agony",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 13, 2013, 12:34:53 am",
"content": "the R3,R4,R5,R6 - they all were marked as \"105\" - 105 should be 1M.But when i did some measuring - had a unregulated DC supply (17.6V under load) - the current was very close - 7mA.Thats what simulation gets me with 720k ohm resistors. With 1m ones the simulation suggested a 11mA - way mroe then it actually measured."
},
{
"post_id": "",
"author": "David_AVD",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 13, 2013, 02:09:08 am",
"content": "Measure the resistors out of circuit and tell us what they read."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 13, 2013, 02:42:22 am",
"content": "Quote from: Agony on May 13, 2013, 12:34:53 amYou're not listening and/or reading...You can't measure the value of those resistors \"in-circuit\". There's too much other stuff going on.And an unregulated 17.6v. Who knows what kind of wave garbage is coming out of that thing..."
},
{
"post_id": "",
"author": "metalphreak",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 13, 2013, 02:38:02 pm",
"content": "You should look up how a voltmeter works. Also understanding that taking a measurement at two points is between two \"nodes\", so anything connected between those two nodes is measured. It might give you some clarity as to why you're getting the result you are.The multimeter is putting out a small test voltage, the current from this is travelling through all the resistors in the circuit. What you are measuring is the combination of all the resistors at once in that configuration. You pretty much have to remove most components from a circuit if you want to test their values."
}
] |
2025-10-17T20:22:20.142582
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1070ti-please-connect-power-connected/
|
1070Ti "Please connect power" - connected - Page 1
|
[
{
"post_id": "",
"author": "elior77",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 14, 2020, 07:00:47 am",
"content": "Hey !I got this ASUS 1070 Ti, when I turn it on I get \"Please power down and connect the PCIe power cable...\"The back side of the card was very dirty and has some signs of corrosion, I work at an Electronic factory so I have every thing needed for repairs, I got the card cleaned and re-soldered any bad pads found.I understand the the INA 3221 chip is responsible for voltage monitor on the card, I replaced it - still the same.btw, all the voltages I expect to see are there, mem,gpu,pcie,5v,1.8v ...I would love some help here, as I understand it the the card does not start normal start up for some reason.Thanks !Elior"
},
{
"post_id": "",
"author": "ConKbot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 15, 2020, 02:53:26 pm",
"content": "Is it an 8-pin PCI-E power connector? Given that its the same number of power pins as a 6-pin, and just 2 extra grounds, see if one of the ground pins is being used to sense the 8-pin plug being connected, and if there is a faulty joint, or visible cracked trace. No specific guidance on how to diagnose, as I'm not sure what a typical implementation is for them, but I do know at least some cards can tell if a 6 or 8 pin is plugged in."
},
{
"post_id": "",
"author": "elior77",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 19, 2020, 07:06:21 am",
"content": "It has 1x8pin PCI-E power connector, there no cracks, the card is like new on the gpu side, it is just the back side that suffer from liquid attack...I source reason for the problem is the liquid that got spilled on the back, I tried to take care of all the visible corrosion but I something is still not right."
}
] |
2025-10-17T17:49:45.476989
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10937p-50-chip/
|
10937p-50 chip? - Page 1
|
[
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 21, 2018, 05:07:44 am",
"content": "How the heck do you use this chip? I have close to thirty of them I pulled off of busted vfds from old snack vending machines. I would like to use them to drive 14 segment led displays. I figured it was possible because the data sheet says it can be used for both led and vfd. I can't get it to work at all, I've tried three chips so far. I know the chips are good because I have a test rig setup with a socket on an original working display board...I'm under the impression that they are powered from 5 volts and I already have data being sent to sck and data via an arduino. I get nothing on the led displays and all the pinsare at 0.0 volts... I can attach a data sheet of needed but a quick Google search will also bring it up. Any help would be really appreciated. I've been on this now for three days straight..."
},
{
"post_id": "",
"author": "daryl_uk",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "May 22, 2018, 01:57:43 pm",
"content": "Would be helpful if you could post your schematic of your circuit design for de-buging."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 23, 2018, 07:19:14 am",
"content": "Unfortunately I don't have a schematic for what I have on the breadboard. All I have is 5 volts hooked to vss pin, and the vdd pin at ground. Of course I also have the reset, sck and data lines hooked up to the arduino. Furthermore I have the reset line tied to the arduino via a pnp transistor like it shows in the dataset with some resistors. I have all the grid and anode control pins tied to ground via 100k resistors.My main question is on how to use this chip with 14 or 16 segment alphanumeric displays like it says can be done in the datasheet?"
},
{
"post_id": "",
"author": "Whales",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 23, 2018, 09:46:58 am",
"content": "We can't help you at all if we can't see what you're doing, there are an infinite number of things that can go wrong with any circuit. Draw a full schematic of what you have made on a piece of paper and post a picture."
},
{
"post_id": "",
"author": "hsn93",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 23, 2018, 11:42:22 am",
"content": "im not sure but i think the arduino clock is faster than what the chip can handle?"
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2018, 01:29:10 am",
"content": "Rockwell 10937 VFD controller, I remember them in zig-zag package decades ago, but there are DIP and PLCC parts too.Micrel bought the line and has them as MIC10937-40, 10937-50, MIC10957-40 and 10937-50. Datasheets are on the webhttp://www.datasheetcatalog.com/info_redirect/datasheets/400/27307_DS.pdf.shtml"
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2018, 03:17:39 am",
"content": "The Micrel datasheet shows that the IC requires a 15V supply... for example +5V and -10V. Check the supply voltages on the original board."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 24, 2018, 07:53:22 am",
"content": "Okay I got the chip to power up. I'm using an at power supply at the moment using the 5 volt rail and the negative 12 volt rail going through a negative voltage regulator to bump it back down to -10 volts.Now where I'm stuck at is to get it to drive 14 or 16 segment ked displays. Could someone have a gander at the dataset and clarify how to hook up led instead of a vfd glass?"
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 24, 2018, 09:47:06 am",
"content": "Here is the schematic of what I have so far..."
},
{
"post_id": "",
"author": "Whales",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2018, 10:53:39 am",
"content": "Your schem shows nothing but resistors instead of LEDs. Good -- see what it does to them before going any further; don't worry about LEDs until you first get the chip itself working.QuoteMake sure to use a scope (not a DMM) as the chip will be multiplexing those pins at high freq.Missing from your schem is the Arduino. (1) Have you joined grounds? (2) Have you scoped your data and clock to make sure the chip is getting what you think you're getting?EDIT: You have the power-on reset (POR) pin controlled differently to what the datasheet shows. The DS shows it being driven with 0 to 5V, you're doing it -10 to 5V. That's outside the max spec of this part? I presume the resistor will current limit it, but it would still be worth checking out.Actually I might be misreading here.Oh, and a pox on you for drawing a P-type part upside downAll the holes will fall out. You're just trying to confuse me whilst I'm sick."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 25, 2018, 04:44:05 am",
"content": "Sorry about drawing the transistor upside down lol. I did that so the pins were on with where I had it in the schematic lol.I do have the grounds from the schematic also tied to the arduino. I didn't see a point in sawing the arduino in this schematic because that isn't where my issues lie.I think what I'm now trying to ask is what type of displays to use (common anode or common cathode). How to hook them to the circuit (directly, with limiting resistors, with mosfets, with mosfets on the grid and anode drivers)? I've already assumed that I need to use common cathode because the segment drivers say anode in the datasheet...Right now with that schematic, the chip does work."
},
{
"post_id": "",
"author": "Whales",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 26, 2018, 09:18:43 am",
"content": "I've just been trying to think how you could use the wrong display type (common anode vs common cath) on this chip and get away with it, but my addled brain isn't letting me.Problem (1): voltage swing. The ADx and SDx outputs look like the might be pull-up only (relying on external pull-down resistors), so if you have split rails (eg +5V, GND, -5V) then you should be able to be clever and cheat the voltage directions to light your LEDs.Problem (2): output patterns. This device will strobe the display, but if it does it inverted then persistance of vision will be ruined (all segmentsexceptthe one you want will light and show digits). You'd have to use external inverter chips to fix this.Given how digital this device is (serial interface and all) I'm surprised there's no internal option or bit to flip to change between common anode and common cathode. The only info I found suggesting the common type is the timing diagram (figure 1 on page 5).The fact the datasheet does not mention the common type suggests I'm completely missing something. Maybe it's just expected to be of one type, or maybe there's some clever way of using either common anode or cathode that I can't figure out.Sorry hydrolisk"
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 26, 2018, 02:40:11 pm",
"content": "Quote from: Whales on May 26, 2018, 09:18:43 amYou can use common cathode displays with either direct segment drive or non-inverting segment drivers (NPN emitter followers).For common anode displays you would need inverting segment drivers (NPN common emitter).For common cathode, you also need inverting digit drivers (NPN common emitter).For common anode, you need non-inverting digit drivers (logic inverter + PNP common emitter?).They don't bother showing LED drive on the datasheet because it's really intended for VFD drive."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 26, 2018, 09:49:42 pm",
"content": "Quote from: edavid on May 26, 2018, 02:40:11 pmSo if I'm understanding you correctly, if I need to invert the signals coming from the chip, I'd need to use something like a 74hc14?For pull up and pull down resistors, I'd pull the anodes low and pull the cathodes up?For the npn solution I'd hook the base of the transistors via a resistor to the segment and grid driver pins? Thanks for the information you have given so far, it has helped me quite a bit so far.P.s. the only spot in the dataset that show's any indication of using led is on the first page. But that is it. I've scored the Web for a different dataset that might show the led example bit I've gotten no where. That is why I came here."
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 26, 2018, 10:00:38 pm",
"content": "Quote from: hydrolisk1792 on May 26, 2018, 09:49:42 pmThat would be OK.QuoteI don't see why you would need them (unless driving a 74C14 or MOSFET).QuoteYes, but you only need base resistors for common emitter transistors."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 26, 2018, 11:14:19 pm",
"content": "The 10937p-50's a royal PITA to use with LEDs - you'd be far better off chucking them or it back in the parts bin and either using it with a VFD or, if you must drive starburst LEDs, using a string of 74HC595 shift registers and a handful of MOSFETs (or TPIC6C594 power shift registers) and segment limiting resistors, all run from a single positive supply, with the Arduino providing the segment pattern for each character.However if you *MUST* use it, possibly for a LED conversion of an existing VFR display, a VFD has active high character grids and segment anodes but a starburst LED display has either active high character anodes and active low segment cathodes if its common anode, or visa-versa if its common cathode.A 10937p-50 is only good for up to 20mA of segment or character drive, so if you are using it with starburst LEDs, it strongly favours using common cathode characters, with a NPN transistor for each cathode so it can sink the worst case 200 mA of a character with ten segments on. Each transistor needs a base resistor to limit the base current and each segment anode needs a current limiting resistor to stay under the 10937p-50's 20mA output rating. You could use ULN2003 or ULN2803 ICs (depending on the number of characters you need) for a reduced parts count solution with all base resistors integrated.If you are stuck with common anode LED characters, you'll need a NPN emitter follower on each 10937p-50 ADx pin to get enough current, and you'll still need 14 or 16 inverting drivers for the segment cathodes, + resistors to limit the segment currents to whatever the display is rated for. One could use 14 or 14 discrete NPN common emitter transistors + base resistors but the parts count is fairly ridiculous so using 2x ULN2803 or ULN2003 is preferable. Due to the voltage levels involved a 74HC14 is useless. In all cases, to minimise dissipation in the segment resistors, unless you are driving blue LEDs or ones with multiple series dies per segment, the ULN2803 or ULN2003 chip's common emitter pin (GND) should go to 0V not your -10V 10937p-50 Vdd supply."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 28, 2018, 04:25:54 am",
"content": "Quote from: Ian.M on May 26, 2018, 11:14:19 pmCould I use td62783apg instead of the uln2003 solution because I have a lot more td62783apg than uln2003."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 28, 2018, 04:43:46 am",
"content": "No. The td62783ap is non-inverting and is high-side not low-side, so it cant replace a ULN2003 or ULN2803. If you can tolerate its higher voltage drop, you could however use it instead of the discrete NPN emitter followers for the character anodes if driving common anode starburst displays. You'd still need two ULN2003 or ULN2803 chips for the segment cathodes."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 28, 2018, 09:50:56 am",
"content": "Okay I understand now, that makes sence why you selected the uln chips.So to sum it up, I'll put the uln chips at the grid drivers and as for the segment drivers, just limiting resistors? Just making sure I understand what you are telling me without a schematic. I may throw a schematic together off the original one I posted to visually see what you are saying.I do have a lot of electronics experience and work with electronics for a living so I think I get the gist of what you are saying."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 28, 2018, 10:52:42 am",
"content": "Yes I think you've got the idea. State whether your starburst LEDs are common anode or common cathode, 14 or 16 segment, their LED Vf (measure one segment @ 10mA if you don't have official data) and post a schematic as PNG or GIF and I'm happy to check it for you."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 29, 2018, 12:47:31 am",
"content": "Okay. I have some common cathode displays, and I usually go by the 2.1v 10ma thing when dealing with unknown leds.Quick question, when using these chips with the actual vfd glass, what is a good filiment voltage to use? AC or DC? Working on another one because I found that one of the glass are still good that I have."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2018, 06:32:55 am",
"content": "LED Vf is highly dependent on colour Your 2.1V 'guesstimate' will only be typical of GaAS (Gallium Arsenide) amber, yellow and green LEDs and *SOME* GaAS red LEDs.However if your LEDs are over 2V Vf, due to the voltage drops in the 10937p-50 segment drivers and the ULN2003/2803 inverting cathode drivers it looks like there wont be enough headroom to run the LEDs between the +5V rail and ground and still have enough drop across the segment resistors to accurately set the current , so you'll have to return the cathode driver to your -10V rail. If you wanted to run them between 5V and Gnd, you'd need to use MOSFETs (with gate pulldown resistors) for the cathode drivers to avoid the high Vce_sat drop of the Darlingtons in the ULN2003/2803.Whether you need to run a VFD filament on AC or DC depends on the filament length, and how much brightness variation you can tolerate across the display due to the voltage drop across a DC filament resuting in a different anode-cathode voltage for each digit. Get it going on DC, and if you don't like the results, build an AC filament driver.To find the filament voltage for an unknown VFD with no data, if possible, measure the RMS voltage across the filament (using a scope or true RMS meter that can handle the filament drive frequency) in the equipment it came out of to give you a starting point. Otherwise, in a dimly lit room, connect just the filament to a PSU that goes right down to 0V. Observe the VFD, shielding it from as much external light as possible, and *SLOWLY* starting from 0V turn up the voltage till the filament has a barely perceptible dark red glow. If you can observe the glow under normal domestic room lighting, you are almost certainly over-driving the filament."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 29, 2018, 08:39:04 pm",
"content": "So for the vfd question, I went ahead and measured one of the original displays in working condition. It measured spot on 5vac with my fluke 87 true rms DMM."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2018, 09:51:13 pm",
"content": "So, next check that as described above with a bench supply, wind the voltage up to 5V DC (while keeping an eye on the filament to make sure it doesn't get hotter than a very dim glow) and measure the filament current, which you'll need to design a supply for it.Also, while you can, measure the supply rails to the VFD driver, the DC bias on the filament (check both ends), and the negative voltage feeding the grid and segment pulldown resistors, to get an idea of the anode-cathode voltage it needs, and the extra grid bias for cutoff. See Fig.4 Partial System Schematic in the 10937p-50 datasheet to get an idea of what voltages you are looking for.That gives you enough data to put together something that should work first time - either a 6.3V filament transformer + a dropper resistor, or drive a MOSFET H-bridge powered from your 5V rail, with a 50% duty cycle squarewave, then capacitively couple its outputs to the ends of the filament so you can bias the filament to a suitable negative voltage. If you use a BJT H-bridge, you'll need a somewhat higher supply voltage to compensate for its Vce_sat voltage drops.Either way you'll need a resistive divider across the filament to fake a center-tapped 5V transformer. I'd start by using resistors of about 5x the filament hot resistance. Again see fig.4 - your drive circuit replaces the CT transformer and AC source shown directly below the VFD. The center tap of the two resistors goes to the cathode of the bias Zener Ek.The pro-grade alternative of a Royer or similar power oscillator driving a miniature transformer to provide both a CT 5V RMS secondary and a suitable output to rectify to get the -Vdisp supply is just too much design + experimental work for a one-off to make sure the filament voltage doesn't change excessively as the load on -Vdisp varies, unless you can simply reverse engineer the oscillator + transformer circuit from the donor equipment and reuse the transformer frim it."
},
{
"post_id": "",
"author": "hydrolisk1792",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 30, 2018, 11:26:00 am",
"content": "Actually the last part of your post is exactly what I'm doing for the one off vfd I'm doing. I was given another one off a jukebox that had a busted glass and I'm going to use that transformer. My mate also gave me a schematic for that display, so I don't even need to reverse engineer the board.As for the LED verson in the OP, I'm waiting on more displays to come in the post.Now I'm assuming on the LED verso I don't need the negative bias for the pull down resistors, I can just put them at ground, right? Or should I keep that true to the datasheet?"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2018, 08:43:41 am",
"content": "Sorry it took me so long to reply - I've had a lot of non-EE stuff going on so didn't have time for a properly considered reply earlier.Quote from: hydrolisk1792 on May 30, 2018, 11:26:00 amThe off-state output leakage per driver is specced at 10uA max. so you don't actually need any pulldown resistors for the LED version unless you are driving a BJT or MOSFET. The ULN2x03 chips include an internal base-emitter pulldown. You certainly don't need a large negative bias for the pulldowns - that is only to get a high enough Vak for sufficient brigtness for multiplexed VFDs. For any output that needs a pulldown, simply take the pulldown to whichever rail (Gnd or -10V) sinks the current from the LED cathode drivers."
}
] |
2025-10-17T18:31:28.604070
| 26
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10a-buck-converter-rc-sevos/
|
10A Buck Converter - RC Sevo's - Page 1
|
[
{
"post_id": "",
"author": "Docara",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 13, 2018, 07:49:27 am",
"content": "Hi,I'm just looking into the feasibility of driving a couple of RC Servos from an automotive source and would like some advice.First off the Servos will be either 7 or 8.4V and have a stall current in the range of 6-8A. And the Power cables would need to run approx. 2-3m.Now I have only ever needed linear power supplies up to 2A so I've used our old friends the 78xx series. It is tempting to buy one of the multitude 10A+ Buck converters from our favourite auction site, but I don't know the implications are of using Buck converters with reference noise etc to surrounding equipment and to the electronics on-board the servos themselves - not to mention the long-term reliabilityThe alternative is to trawl through datasheets and use manufactureres application circuits to knock up a circuit without knowing good PCB layout practices or experience in this area.Your thought would be most welcomeThanksMatt"
},
{
"post_id": "",
"author": "AustinR",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "August 14, 2018, 01:21:57 pm",
"content": "Reliability is component-specific, so I cannot comment on the longevity of using specific buck converters long-term.However, I can comment a bit on controlling output ripple. Without knowing the specific application or requirements, I don't think you'd have to worry about servo issues too much, but using a capacitor on the output side of the buck converter should reduce how much ripple your servo is seeing.I found a decent video on youtube covering this here:https://youtu.be/G-Llhy2ViUYHope it helps!"
}
] |
2025-10-17T18:27:08.966620
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10a-current-source-vin14-5v-vout12-5v/
|
10A current source; Vin=14.5V, Vout=12.5V - Page 1
|
[
{
"post_id": "",
"author": "Myster E",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 30, 2020, 05:15:08 am",
"content": "I'd like to ask you in the EEVblog community for thoughts, opinions, advice, etc... on building a 10A current source for charging a deep cycle battery from my vehicle's alternator. Common alternator output is about 14.5 V, and the battery's voltage while under a 10A charge would range from 12.5 to 14.5 V, increasing with state-of-charge (SOC) from 20 to about 90%.I'm planning to replace my van's starter battery with a deep cycle battery (group size 24; ~ 80Ah). I need to limit the charge current to 10A, in line with the recommended max bulk charge rate of 0.13C for flooded batteries. This also saves on alternator stress.Here's what I've been considering:option 1 - do nothing: just swap batteries and move onoption 2 - off-the-shelf device: a DC-DC charger? probably out of my price range... and probably overkill...I'm happy with the alternator's constant voltage function; just need to fill in the constant current partoption 3 - linear regulation: sounds barbaric... but is it?option 4 - switch mode regulation: that's out of my league right now... but I'm up for it if it's the way to gooption 5 - pulsed regulation: ... like a lot of solar chargers do it?option X - anything outside of my box sofar...I have a few opinions on these options, but I'll save them while I'm listening...What do you think?"
},
{
"post_id": "",
"author": "DenzilPenberthy",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 30, 2020, 11:38:03 am",
"content": "Honestly, this doesn't sound like a good idea for a number of reasons.- your starter battery is much better suited to cranking the engine than a deep cycle battery- if you somehow limit the alternator output to 10A, that probably won't even cover the vehicle's consumption. Let alone once you turn on the headlights, windscreen wipers and blower motor. Your battery will run flat.If you want a deep cycle battery in your van for some reason like using an inverter, then leave the starter battery and alternator as it is. Fit a deep cycle as a second 'leisure battery' and charge it from the vehicle through a 'split charge' system.Cheap version is a voltage sensitive relay which connects the leisure battery when the alternator is running.e.g.https://www.12voltplanet.co.uk/split-charge-relays.htmlBetter version, especially if you want to limit charge current or have a new vehicle with a 'smart' alternator, is use a DC-DC converter. e.g:https://www.12voltplanet.co.uk/battery-to-battery-chargers.html"
},
{
"post_id": "",
"author": "Myster E",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 30, 2020, 07:47:57 pm",
"content": "Many thanks for your post Denzil.Perhaps I should share a bigger picture of my plan:Parallel to the battery there is an engine start module (ESM) - a scaled-down version of thishttps://www.maxwell.com/products/esm/.It's a bank of supercapacitors (240F x 15V) with a balance circuit. It does the heavy lifting during starts. It lends a hand during peak surges - hard braking, steering ...I'll install that first next to my current starter battery, which has been struggling lately. It should extend said battery's useful life. There's a handful of YouTubers that have done similarly for their vehicles.The starter battery will be replaced with a deep cycle battery. I'll continue to rely primarily on the ESM for starting duties. In the worst case the ESM should start the vehicle after allowing the surface charge of a flattened battery recover to 11V or so.Now, I want to spare the alternator from routinely recharging a battery from a 50% or even 20% state-of-charge (SOC). This would also be of concern with the conventional leisure battery + isolator arrangement, as you suggested. The vehicle's charging system isn't suited for this. Hence my wish for a current regulator. It will limit current into the battery (iow it's a charge controller); it will not otherwise hinder alternator output.Lastly, the plan calls for an ideal diode circuit (https://www.ti.com/product/LM74610-Q1) bypassing the current regulator; it allows current to pass (virtually) unhindered out of the battery. Hence, the vehicle's power sources are: 1) the alternator for steady-state power, 2) the battery through the ideal diode for intermediate-term power, and 3) the supercap bank for short-term power.Let's start another thread should this plan attract further discussion.... Now, about the current source:Picture a conventionally isolated auxiliary battery charged from the vehicle alternator. I would still want a current regulator to limit bulk charging current... for the sake of the battery and of the alternator. In this topology I would call it a \"current-limited battery isolator\". I figure I don't need a DC-DC solution, since there's nothing 'smart' about my '92 Astro van's alternator, and since resistive losses should be minimal with the battery housed under the hood (GB-EN: 'bonnet')... current regulator dropout losses notwithstanding.cheersMr. E"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 30, 2020, 08:44:32 pm",
"content": "The typical way to handle multiple batteries in things like RVs and boats is to use a battery isolator which is nothing more than a pair of heavy duty diodes in a housing. My dad's sailboat has a pair of large deep cycle batteries and there is a manual switch that lets you select Off-1-2-Both. IIRC it is a make-before-break type so it doesn't let the alternator run unloaded as you switch from one configuration to another.You want to make sure that you're not limiting the output of the alternator to power other accessories, some of those can draw quite a lot. If it has an electric primary cooling fan that can pull 50+ amps. The HVAC blower can pull another 20-30 amps, same with the electric rear window defogger, headlights are 10-12A, it all adds up.If you do decide to build some kind of regulator, make sure you take into account the fact that an automotive electrical system is notoriously dirty. You can get all kinds of spikes well beyond the nominal 12V, and it can dip down as low as 6V or so cranking the engine on a very cold day."
},
{
"post_id": "",
"author": "Myster E",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 30, 2020, 11:56:20 pm",
"content": "Thanks for your post James.james_s wrote:Quotejames_s wrote:QuoteI've moved and responded to these comments in a new thread: \"Replacing starter battery with deep cycle battery\"https://www.eevblog.com/forum/renewable-energy/replacing-starter-battery-with-deep-cycle-battery/james_s wrote:Quote... not to mention reversed battery conntections (-12V), 24V jump starts, suppressed load dumps (up to 40V for a second or more), or even unsuppressed load dumps (100V+); a possibility in my crate, a '92 Astro van.I've already designed a front end for any regulator I will build. It covers:electrostatic discharge (ESD) and other spikesunsuppressed load dumps (I have no idea if my vehicle has load dump suppression)negative input (supercaps reversed)negative output (battery reversed)overvoltage (lockout at 16V)input filter for regulator circuits"
}
] |
2025-10-17T17:38:17.390471
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10a-device-in-15a-socket-vice-versa/
|
10A device in 15A socket vice versa? - Page 1
|
[
{
"post_id": "",
"author": "Dokroma",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 05, 2020, 02:49:20 pm",
"content": "How come you can plug in a 10amp device into a 15amp wall socket but not a 15amp device into a 10amp socket? Wouldn't plugging the 10amp device into the 15amp cause it to blow?"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 05, 2020, 04:07:09 pm",
"content": "A 15 A socket means it can tolerate currents up to 15 A, and has a fuse or circuit breaker rated for that. What can you possibly mean here?"
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 05, 2020, 04:12:03 pm",
"content": "The device \"decides\" how much current it takes. Sockets, wires, power supplies are rated for a maximum current. Generally, the wall socket and house wiring cannot actually reduce the current the device takes, the only thing it can do is to cut it completely if the limit is exceeded, using traditional fuses or modern high-tech alternatives."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 05, 2020, 04:24:20 pm",
"content": "An ideal model for the wall socket in ones house is a constant-voltage source with a switch (circuit breaker or fuse) that opens when the current exceeds the set limit. If you connect a shorting plug, the switch opens but the huge current will flow momentarily, long enough to flip the switch from on to off."
},
{
"post_id": "",
"author": "garethw",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 05, 2020, 04:36:16 pm",
"content": "An ideal voltage source will supply what ever current is needed to keep the voltage at the desired level. For example, mains in the US is 110V (I'm in the UK so ours is 240V). If you plug in a phone charger for example, it will only draw a few hundred mA at most. That is all the circuit consumes. Plug in a kettle and suddenly you need 10A to keep the voltage at 110V. The device will consume what it needs.A current source, however is a different story. It will generate a voltage that is required to cause a set current to flow.If I have a 100V DC voltage source with a 1A rating and I connect a 1000 Ohm resistor across the terminals I get:100V / 1000 Ohms = 0.1 AIf I upgrade my voltage source to a 100V DC with 100A rating and connect the same 1000 Ohm resistor I get:100V / 1000 Ohms = 0.1 AThe current rating has no effect on the current consumed."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 12:53:01 am",
"content": "Quote from: Dokroma on July 05, 2020, 02:49:20 pmAs others have said, the device draws just the amount of current it requires.A moment's reflection reveals this is obvious------otherwise you would have trouble using things like phone chargers from the normal 10 amp sockets.The other way around is where you can get into big trouble.----it is an evil habit in Oz amongst some sections of the community to file the large \"Earth\" pin on a 15 amp plug down so it fits in a normal domestic 10 amp socket.Sometimesthey get away with it!For non-Oz folks:-The normal 10 amp plug is similar to the Chinese one.For 15 amp, the plug looks similar, but the \"Earth\" pin is made larger, so that it won't fit into a 10amp socket.The 20 amp socket looks still looks similar, but the \"Active\" & \"Neutral\" pins are larger, & the \"Earth\" pin is round."
},
{
"post_id": "",
"author": "helius",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 02:09:51 am",
"content": "Quote from: vk6zgo on July 06, 2020, 12:53:01 amIn North America, a similar quick & dirty technique exists to fit a 20A plug into a 15A socket: one of the blades of the 5-20P is rotated 90 degrees from the corresponding part of a 5-15P. Take out the channellocks and twist the blade so it fits—you may get away with it if the equipment doesn't actually use more than 1800W."
},
{
"post_id": "",
"author": "Dokroma",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 06, 2020, 02:19:13 am",
"content": "Quote from: vk6zgo on July 06, 2020, 12:53:01 amAnd how does the device decide how much current it should get? Through the resistance? But then what about if the device needed 10amps exactly, wouldn't the device e.g a kettle need 0 resistance in its circuitry? But then wouldn't that cause it to blow up since don't circuits need some resistance? I am very new to electronics and amps confuse me, along with volts."
},
{
"post_id": "",
"author": "0culus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 02:42:13 am",
"content": "Quote from: Dokroma on July 05, 2020, 02:49:20 pmBecause drawing 15 amps will trip the 10 amp breaker on a 10 amp circuit. The quoted rating of a circuit is the MAXIMUM allowable current on that circuit before a protective device trips. A 15 amp circuit will happily supply 10 amps @ standard wall voltage for your area all day long."
},
{
"post_id": "",
"author": "John B",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 03:35:09 am",
"content": "The 10A and 15A ratings refer to an acceptable standard of self heating in the switches, wires and power cords. Take out the circuit breaker for the moment - more than 10A or 15A is capable of flowing through either circuit, but the temperature of the whole system may rise to a dangerous level and pose a fire hazard.Remember that the circuit breaker is to protect the rating of the circuit, the circuit isn't built to the rating of the circuit breaker (ie, the circuit safety margin should exceed the circuit breaker)Of course, that doesn't rule out the existence of BAD wiring."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 06, 2020, 03:47:39 am",
"content": "You need to pay more attention to Ohms Law. The voltage is a key part of the situation! (Just stick to resistive loads for the moment until you get your head around this.)Quote from: Siwastaja on July 05, 2020, 04:12:03 pmThis is the key fact ^ ^ ^ ^ ^QuoteYes, sockets and circuits are able to supply UP TO their rated current. Imagine you power bill if every device plugged into a 10A socket pulled 10A!!!!You can have a device that needs 1 amp - and that's all the current it will take. The socket cannot force any more current than that down its throat.It is also the reason our power points in Australia - which look like these below - will allow you to insert a 10A plug into a 10, 15, 20, 25 or 32A(capacity)socket. The same can be said for any plug - it can be inserted into a socket of matching orhigherrating, but NOT into one of lower rating.The reason for this is very straightforward.... If a device is one that may need up to, say, 20A, then if you were to plug it into a 10A capacity socket, you would almost certainly overload it - melting things, burning things and possibly setting things on fire - especially if the circuit breaker didn't trip.This is why they are shaped the way they are.As a simple example - if I were to plug a clock radio which requires 0.1A into a socket rated for 10A, 20A or 32A - then the current which would flow would be 0.1A in all cases. It's the 240V (sorry, 230V**)which is important.** Up to 2000: 240V +6% -10%From 2000: 230V +10% -6%"
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 05:12:08 am",
"content": "Quote from: Dokroma on July 06, 2020, 02:19:13 amNo. Ohm's law.Volts = Amps x OhmsVolts is constant in your example, the Volts coming out of your wall in Australia is 240, it doesn't change (ignoring tolerance).The designer of the kettle decides they want to draw 10A from your 240V supply, so they use Ohm's lawVolts = Amps x Ohmsthey plug in what they know240 = 10 x Ohmsand rearrange the equation to work out what they don't know240 / 10 = Ohmsand now they can make thier heating element be 24 Ohms, and that will draw 10A on the 240V supply.(For sake of simplicity, I have just accepted that your imaginery designer chose 10A, rather than based their decisions on some other reasons like desirable time to heat the water and the power required to do that)."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 06, 2020, 05:24:44 am",
"content": "Quote from: Dokroma on July 06, 2020, 02:19:13 amYes, you certainly are confused. It's good that you are honest about this as it shows you really want to understand. So we will try to help you get there.First things first... There aresourcesof energy and there areconsumersof energy. (They bothcanbe complicated - but we will stick to simple examples*1to help you \"get it\".)Energy supplying devices come with two basic parameters:1. The nominal voltage they provide - which is usually fixed*12. Themaximumcurrent they areableto provide.Energy consuming devices come with two parameters as well:1. The nominal voltage they are expecting - which is usually fixed*12. The amount of current they need to do their job.Standard operating scenario:1. Voltages need to match (within allowed tolerances)2. Current required from the consuming device should be less than or equal to the maximum current the source device is able to provide. Actual current flow is determined by the consuming device.The Water Analogy.It is an old analogy - but a very good one to get a grasp of a few basics....Let's just start with a very basic example - a dam with a pipe at the bottom.Consider voltage as pressure (in fact, voltage is sometimes referred to as electrical pressure). The higher the voltage, the greater the pressure and vice versa. No water needs to flow for this pressure to exist.Lets look at our dam with the pipe blocked off. We could measure the pressure in the pipe. The higher the water level, the higher the pressure.Now let's open the pipe ... water will flow - but how much water will flow? That will depend on the pressure and the size of the pipe (and anything along the pipe that could affect the flow of water - but don't worry about that just yet).Next step is we run a big pipe (say 30cm dia.) to somewhere. This pipe is capable of carrying a lot of water - but when we get to the somewhere, we connect a 1cm dia. pipe to it. Here, the amount of water that flows depends on the smaller pipe, not the big one.Electricity works in the same way."
},
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 07:08:20 am",
"content": "Quote from: Dokroma on July 06, 2020, 02:19:13 amThe wall outlet provides a certain voltage and up to a certain amount of current at that voltage -- e.g. 230V and a max of 15 amps.If the kettle needs exactly 10 A it will set its resistance to 230/10 = 23 ohms.Of course, simple devices like kettles have a fixed resistance, so in this case the manufacturer will design the kettle to have a resistance of 23 ohms.If you plug that kettle into a 115V outlet it will draw half as much current -- 115V/23 ohms = 5A.This is why some devices which are made to work around the world have a switch which tells the device why kind of power (115 vs. 230) is coming in on the mains socket -- like the little red switch you find on the back of PC power supplies:"
},
{
"post_id": "",
"author": "Circlotron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 07:16:49 am",
"content": "It's like saying you can safely put a 10 ton load on a 15 ton bridge, but you can't safely put a 15 ton load on a 10 ton bridge. The amps rating of the outlet is what it will tolerate, not what it supplies to any load. The load determines the amps, not the supply.*Of course, we are talking about a voltage source here, not a current source. Let's not complicate things."
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 08:40:19 am",
"content": "Quote from: Dokroma on July 06, 2020, 02:19:13 amSome traditional, simple devices, mostly heaters, by using a specific resistance. I = U/R.More modern devices are, in principle, the same, except harder to analyze for a beginner because the \"actual\" power-hungry circuit, say a battery charger or a CPU, isn't a constant resistance, but it varies, and there are active power converters inbetween.QuoteOh, no, if the designer wants to design a kettle that draws 10A exactly, in a 110V system (now this depends on the country), they design in a 11 ohm heating element. Current = voltage / resistance. 110V / 11 ohms = 10A. Job done! Of course, if you run that kettle accidentally at 230V, say you use a plug adapter, now the 11 ohm element is taking 230V/11ohm = 20.9 A, and the kettle likely burns down.Do also note that current ratings seldom are very accurate. If a 10A socket has a 10A fuse, it's typically guaranteed to blow only after exceeding 15A for a long time (possibly minutes), and between 10A and 15A is some grey area where it may or may not blow. Same thing for the kettle. Cheap manufacturing can't repeatably make exactly 11 ohm heating elements, and the power line voltage isn't exact either."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 09:49:50 am",
"content": "The point is, voltage is the \"pressure\" that forces electricity to flow through a load. (That's why excess voltage can damage a device.) The current is theamountof electricity that manages to flow given the pressure (voltage) and the resistance (think of the size of a hole in a pressurized tank).The current rating of a device is the maximum current it wants to draw when applied to its rated voltage.The current rating of an outlet is the maximum current it can carry safely. But it's the voltage that does the pushing, so a load will never draw more current than it wants to — the outlet can't force current through."
},
{
"post_id": "",
"author": "Dokroma",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 06, 2020, 10:13:06 am",
"content": "Ok, I understand it now. Also, what would happen if someone got shocked by a 230V outlet? What would happen? What about a 120V outlet? Also how long does it take to learn everything about electronics? I only know the names of some PCB components but I don't really know anything about how they work and stuff, but I have some experience with soldering."
},
{
"post_id": "",
"author": "Dokroma",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 06, 2020, 10:17:15 am",
"content": "Also, if I put my multimeter in Amps mode and put the probes in the socket, it would read the internal current of the multimeter right? And not 10Amps?"
},
{
"post_id": "",
"author": "Dokroma",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 06, 2020, 10:36:26 am",
"content": "Also, do any of you make money off electronics? Have you ever made a circuit and put it in a case and sold it? Could I make a high quality product with little mistakes and have it made in China and sold around the globe?"
},
{
"post_id": "",
"author": "atmfjstc",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 11:05:29 am",
"content": "Quote from: Dokroma on July 06, 2020, 10:13:06 amTechnically speaking, depending on the circumstances (and pure luck), a wide range of outcomes is possible, from walking away nearly unscathed, to being maimed or killed in all sorts of ways: cardiac arrest induced by the current, burns, cracking your head against something hard as you are jolted away etc etc.Basically something you should avoid if at all possible."
},
{
"post_id": "",
"author": "atmfjstc",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 11:08:53 am",
"content": "Quote from: Dokroma on July 06, 2020, 10:17:15 amA multimeter in Amps mode acts like a short across its terminals, so plugging it in the mains is the same as plugging a simple wire in the mains. Oops. Don't do it, unless you want bad things to happen to your multimeter, the socket, and possibly your hands."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 06, 2020, 11:31:21 am",
"content": "Quote from: Dokroma on July 06, 2020, 10:17:15 amNO!DO NOT DO THIS!There is a VERY BIG DIFFERENCE in using current measurements and other measurements.This is a very softly stated description of what will happen...Quote from: atmfjstc on July 06, 2020, 11:08:53 am"
},
{
"post_id": "",
"author": "Halcyon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 06, 2020, 11:34:34 am",
"content": "Quote from: Dokroma on July 06, 2020, 10:13:06 amThe day you stop learning in *any* trade is the day you should just give up. You never stop learning."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 11:58:13 am",
"content": "Quote from: Dokroma on July 06, 2020, 10:13:06 amIt takes ∞ years. Because it's literally impossible to know EVERYTHING about a topic — there'salwayssomething new to learn.I think you need to start with the basics and go from there. Don't do anything with AC yet — you're not ready."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 06, 2020, 11:58:27 am",
"content": "As someone who clearly understands very little, what the hell are you doing anywhere near the mains? Just stick to your batteries and 3V light bulbs fore now!"
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 12:13:14 pm",
"content": "Quote from: Dokroma on July 06, 2020, 10:36:26 amMany of us work, (or in my case, used to work) for a company, or govt department, etc.Some have their own business, but of these, some sell and/or service stuff made by some other company.These are quite legitimate ways of \"making money off electronics.\"Others do make stuff & sell it, but it can be a hard way to make a living.QuoteWith your present level of knowledge, you \"don't come within a bulls-roar\" of doing that!"
},
{
"post_id": "",
"author": "madires",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 12:55:23 pm",
"content": "It's the same reason as why stickers on power strips tell you to not daisy chain them."
},
{
"post_id": "",
"author": "Dokroma",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 06, 2020, 02:30:38 pm",
"content": "Don't worry guys, I'm not going to play around with mains, I was just wondering what would happen. I am aware that measuring current with a multimeter is dangerous so I haven't done it before. I have used my multimeter though to measure the AC voltage before, I wanted to see if it was going to say 230V or 240V. And maybe I did oversimplify when I meant how long does it take to learn everything, I meant to get proficient at electronics and understand complex circuits, etc."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 02:43:44 pm",
"content": "There is algebra in the real world, but it is all \"story problems\". Here's a simple thought experiment: you can do the sums without a calculator1. Assume your electric teakettle has a resistance of 24 ohms (independent of temperature) and you connect it to a 240 V source. What is the current? How much power does it dissipate?2. Assume your teakettle has a cold resistance of 24 ohms, but when it reaches operating temperature the resistance increases to 48 ohms. What is the current at the instant when you turn it on? What is the current after it reaches operating temperature? What is the power in the two cases?The resistance numbers were chosen to make the arithmetic simple, but it is true that the resistance of a normal heating element increases with temperature.3. What would happen if the resistance decreased with increasing temperature, and why would that be a bad thing?"
},
{
"post_id": "",
"author": "tpowell1830",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 06, 2020, 04:49:33 pm",
"content": "Dokroma, from your questions, I can tell that you are curious and interested in electronics. However, the problem is that you obviously have not studied and are not familiar with Ohm's Law or have electrical/electronic training. Ohm's Law is the very first thing that you learn when you take a course in electrical/electronics and one of the first courses that are required when you start is electrical safety and CPR training (at least here in the US). Meters have ratings that show the allowed maximums that your meter can safely sustain, so be careful that your meter is rated to measure the AC voltages of your mains. I have seen meters explode when measuring voltages exceeding the meter's ability. This may seem a bit hyperbolic, but mains voltages and current capacities are nothing to take lightly. Over time and experience, you too can safely do this, but training is paramount.With that said, other comments here are trying to point out the relationships in Ohm's Law that pertain specifically to your questions, which is fine, however, I recommend that you take some structured courses in this field from a qualified school before engaging in the field too much. There are many people that decide to take this up as a hobby and do the basics, watch videos, look on the internet, etc. to learn as much as they can, but, they will tell you that it is not easy or quick. There are many learning videos on YT such as Khan academy and many more, just do a search. Without the structured training background, it will be very difficult to do the things that you are asking about. You have to realize that most of the experts on this forum not only have a 4 year degree (or greater) in this field, but also have many years experience. My only point is that if you are interested in the field, be prepared to do the work, because there is much work in learning electronics.If you are only casually interested as a hobby, you will still need many hours of study to get started, but, DO NOT forget the safety training, for your own sake (and for your family or those around you). \"The Art of Electronics\" is a very popular book for the purpose of learning, but you should start with something more basic, like Forrest Mims \"Getting Started in Electronics\".Electronics is a fun hobby, and can be a lucrative career, but it requires a great deal of study. If you don't put in the work to learn it, the return will be equal.Hope this helps..."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 06, 2020, 05:53:23 pm",
"content": "I would suggest he buys a book on the subject. A forum is not a full education program and it's difficult to have a conversation about anything without some common basis of knowledge."
}
] |
2025-10-17T17:46:51.233450
| 32
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10a-fuse-on-multimeter/
|
10A Fuse on Multimeter - Page 1
|
[
{
"post_id": "",
"author": "skillz21",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 08, 2019, 08:49:56 pm",
"content": "I have a multimeter, and for its current measurement, it says it has a 10A fuse. On the back of the multimeter, it says that it contains 2 fuses, one rated for 600v 10A and another rated for 200mA 600v. For this question, I'm going to focus on the 10A fuse. I'm kinda confused about this. Wouldn't you need 6000 watts to blow that fuse? Because technically, isn't it the watts that determine how much heat something is going to create? Or am I very wrong? So wouldn't I, theoretically, be able to measure more than 10 amps? (this doesn't mean that I'm going to, the wires get pretty warm around 8 amps."
},
{
"post_id": "",
"author": "skillz21",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 08, 2019, 09:15:55 pm",
"content": "Quote from: tvl on January 08, 2019, 09:02:38 pmI understand that, yes. Could you please explain to me why the fuse would be blown at 600v 10A? I don't understand, it says it's rated for 600v 10A(that equals 6000w)...? (yeah I understand that 6000 watts is a crazy high number, that what I'm trying to make sense of here."
},
{
"post_id": "",
"author": "cowana",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 08, 2019, 09:18:56 pm",
"content": "The fuse is rated for 10A current. Above that (ignoring the time it actually takes), it will blow. Doesn't matter at all about the voltage.Note that because of the thermal mass of the fuse, it won't instantly blow at 10.001A - the time taken will depend on the current. It can likely survive 15A for several seconds.When it does blow, it will create an open-circuit. It can then cope with up to 600V across it, before it will begin to arc and conduct again (not properly breaking the circuit). Below this 600V limit, it should be fine. This is why fuses have a voltage rating - it just doesn't apply until it blows."
},
{
"post_id": "",
"author": "barry14",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 08, 2019, 09:21:35 pm",
"content": "You are misinterpreting the fuse specification. A fuse rated for 600 volts and 10 amperes will blow when the current through it reaches about 10 amperes irregardless of the voltage of the source feeding it (fuses are not precision devices). Once the fuse blows, it is able to withstand up to 600 volts across it without shorting or arcing. The fuse will never see 600 volts across it and 10 amperes through it (at least not for long)."
},
{
"post_id": "",
"author": "rsjsouza",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2019, 09:21:48 pm",
"content": "Quote from: skillz21 on January 08, 2019, 08:49:56 pmThe meter (and consequently the fuse) is placed in series with the load. In this condition the voltage across the meter and the fuse is very minimal as the fuse has a very small resistance. For example, if the fuse has 0.005Ω of resistance and the current flowing through it is 10A, the voltage across the meter would be: V = R×I => V = 0.005×10 => V = 0.05V. Consequently, the power dissipated on the fuse would be P= V×I => P = 0.5WIn case of an overcurrent event the fuse opens and stays opened, thus the entire supply voltage is present across the meter (and the fuse) terminals. The voltage rating of the fuse expresses how much voltage it can safely sustain across its terminals if interrupted.The 6000W you calculated would be only present on the load under test, if the supply is 600V @ 10A."
},
{
"post_id": "",
"author": "skillz21",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 08, 2019, 09:24:39 pm",
"content": "Ok, it makes so much more sense nowthe 600v is for after it blows, got it! One question, how does it actually know when its 10A? Doesn't the heat produced depend on the wattage?"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 08, 2019, 09:26:59 pm",
"content": "Voltage rating has nothing to do with when fuse will blow or how much power it will dissipate. All that matters is current rating. Voltage rating on the other hand shows what max voltage it is guaranteed to interrupt. If actual voltage is higher than fuse rating, it may start to arc instead of interrupting current flow."
},
{
"post_id": "",
"author": "cowana",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 08, 2019, 09:27:18 pm",
"content": "The fuse will have a certain resistance, say for example 0.05 ohms.When there is 10A passing through it, this will create a specific voltage drop (0.05 * 10 = 0.5V in this case). That equates to 5W dissipation in the element, which melts it.The fuse doesn't care that it was in line of a 12V rail (or whatever it is) - the power dissipation in the element just depends on the voltage dropacross the fuse."
},
{
"post_id": "",
"author": "Adam60",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 08, 2019, 11:23:13 pm",
"content": "Your meter is probably rated CAT III and part of that rating system is explained vefy well above. Google ABCs of multimeter safety by Fluke and you can read about the different categories and their specifications. I believe there are currently 4 of them"
},
{
"post_id": "",
"author": "Nerull",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 09, 2019, 02:56:40 am",
"content": "Quote from: skillz21 on January 08, 2019, 09:24:39 pmOhms law. The fuse has a fixed resistance (well, its probably not actually fixed, but we'll pretend it is). Since resistance is fixed, 10A will always result in the same power. P=I^2 * R.If a fuse requires 1W to blow and has a resistance of 0.1 ohms, than we can calculate that the fuse will blow at I = sqrt(P/R) = sqrt(10) = 3.1A. Thus we would rate that as a 3.1A fuse.The voltage throughout the rest of the device is completely irrelevant to the voltage across the fuse. At 10A a fuse will always drop a given voltage and dissipate a given power depending only on its resistance, no matter what voltages exist elsewhere."
}
] |
2025-10-17T18:18:44.291849
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10ghz-video-transmitter/
|
10GHz Video Transmitter? - Page 1
|
[
{
"post_id": "",
"author": "Corrosive",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 19, 2015, 09:34:00 am",
"content": "Hello all, I'm currently trying to build an amateur tv transmitter using a 10ghz microwave doppler module such as this onehttp://www.amazon.com/SMAKN-Microwave-10-525GHz-Doppler-Detector/dp/B00FFW4AZ4I have managed to modulate audio over this module without any issue however I've never worked with analog video before. I'm looking to hopefully take a composite video source, amplify it with a transistor and then use that to drive the module modulating it on the 5v input pin.Thus far I haven't had much luck, I have managed to get it to transmit on the 10ghz ham band and down convert it with an lnb, sure enough I can pick it up on channel 60, 40, etc. What I see is a black screen while transmitting telling me I have a working carrier frequency.If anyone is interested here is my attempt:Is it possible to modulate video with one of these?EDITI found this in an old magazineNot sure if this will work on this module or not as it's not a gunn diode, but I'll give it a chance if I can salvage the needed components and post back here if it works."
},
{
"post_id": "",
"author": "SL4P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 19, 2015, 07:36:13 pm",
"content": "The black screen is encouraging but I think I'd look at the TV input with a scope, to see how the sync is formed, and it will also give you a better view of what your mod/demod is achieving.I'd also careful where I point that 10Ghz emitter, unless you already have enough children."
},
{
"post_id": "",
"author": "Dago",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 19, 2015, 07:53:37 pm",
"content": "Quote from: SL4P on July 19, 2015, 07:36:13 pmEmitters like this are used in supermarket door openers... It will do absolutely nothing to you even if you sleep with it in your underpants. The transmit power is in the range of 0 dBm (1 mW)."
},
{
"post_id": "",
"author": "SL4P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 19, 2015, 07:56:24 pm",
"content": "Quote from: Dago on July 19, 2015, 07:53:37 pm😉 I'll let you test that theory!"
},
{
"post_id": "",
"author": "BennVenn",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 19, 2015, 08:59:47 pm",
"content": "I believe there is a bit of capacitance inside that module which will severely limit the bandwidth you can pass through it. I assume you are modulating the 5v supply by a few mV? Will be fine with audio (although attenuated) but trying to push through 5mhz might be troublesome. Sync pulses to reconstruct the frame should make it through OK though any video you do get into the transmitter will look pretty rotten on its way out.Maybe remove the decoupling caps in the doppler unit, but it may not oscillate after..."
},
{
"post_id": "",
"author": "Corrosive",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 20, 2015, 12:14:17 am",
"content": "Without the caps I did run into an issue with oscillation, I have no idea what the bandwidth capability is on this thing unfortunately.I do have a scope but it's only a 10mhz model, not sure if it'll work for this application or not."
}
] |
2025-10-17T19:37:00.261098
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10k-2w-sliding-potentiometer-(pot)-for-a-project/
|
10K 2W sliding Potentiometer (pot) for a project... - Page 1
|
[
{
"post_id": "",
"author": "1974mcd",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 01, 2020, 05:05:08 pm",
"content": "Hi humans(I`ve just registered and the machine had at least 3 ways to be sure that this guy was an human, so you are humans also certainly)After a lot of effort to find a 10Ksliding pot capable of handling 2w for my project of a tig welding foot controler without any positive result, i trust this community to clarify me: Are the 10K W sliding pots more rare than unicorns or my search for one of this things has been badly done?Anyone has a reference, or a source for this kind of pot?The other option to build the foot controler is with a rotary pot actuated by a mecanical way to transform linear motion in rotational movement, i`d like to find a more natural way to go from almost no resistance to the 10k, and a sliding pot is as close to that dream as it gets...Any help will be welcome"
}
] |
2025-10-17T17:51:02.740481
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10k-pot-question/
|
10k POT Question - Page 1
|
[
{
"post_id": "",
"author": "Ian",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 04, 2011, 06:04:47 pm",
"content": "HiSo i am working on a project with some leds. My Variable psu can only do down to about 1.4v and my leds are 1.28v. So i was wondering if i use a 10k pot could i use it to control the voltage?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 04, 2011, 06:09:35 pm",
"content": "The normal way to dim LED is to use PWM.A pot will work but you should keep the series resistor in place to protect the LED from the pot being set to full voltage."
},
{
"post_id": "",
"author": "Ian",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 04, 2011, 06:12:41 pm",
"content": "should i use some capacitors to despike the voltage"
},
{
"post_id": "",
"author": "tekfan",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 04, 2011, 06:56:29 pm",
"content": "You could use a big wirewound pot Unless you have a small carbon pot, it is is a very bad solution because it will cause the track to melt inside if you have a bright LED connected to it. I'd put several power diodes in series with the power supply output so you get the voltage drop. You can then have an almost 0 output voltage out of your PSU. Still remember to have a resistor to limit the current going to the LED."
},
{
"post_id": "",
"author": "jimmc",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 04, 2011, 07:13:39 pm",
"content": "Simple answer is that it is not wise to.It is the current through the LED that should be controlled, the forward voltage drop varies from device to device and has a negative temperature coefficient (ie it reduces as the LED warms up).Unless you have good reason not to, it would be better to set the PSU to a higher voltage (say 5v) and use a fixed resistor to define the current [R = (5-1.28)/I] eg for I=20ma R=186R.There is a simple calculator herehttp://led.linear1.org/1led.wiz(note it chooses the nearest preferred value above the calculated value).Unless your pot is something quite special, it will have a maximum power dissipation of 1Watt or less.This is for when all the track is in use so the maximum current allowed will be 10mA (from I = sqrt(P/R)).No capacitors required.Jim"
},
{
"post_id": "",
"author": "tecman",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 04, 2011, 07:18:57 pm",
"content": "I agree with Jim. A simple series resistor is the right choice. Your 10K pot will likely not last since the current will be too high, and control will be next to impossible since yoy need about 1% of the rotation.I would differ, however in the calculation. 20 mA is the usual max current for a typical LED. Most will be bright enough at 5 mA or 10 mA. Use his formula but cut the current for most apps. Also higher supply voltage is better, as Jim indicated, since it will reducte temperature effects.paul"
},
{
"post_id": "",
"author": "Jon Chandler",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 04, 2011, 07:28:34 pm",
"content": "Ummm....forgive me for saying all the replies answered the question you asked but really missed the point.An LED is typically used in series with a resistor, and connected to whatever voltage you want to apply. Connecting an LED without a series resistor is almost never done.The resistor value is calculated to allow the desired current to flow through the LED. An LED has a voltage drop dependent on the current through it. This is the 1.8 volts specified on the data sheet.Vsource = Vled + Vr whereVsource = supply voltageVled = forward voltage of the LEDVr = voltage drop needed across resistor.By Ohm's LawVr = I * R whereI = current in ampsR = resistance in OhmsRather than go into all the details here, please look at two articles I've published:LED CalculationsLED Calculations - The Lab Section"
},
{
"post_id": "",
"author": "sacherjj",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 04, 2011, 07:31:23 pm",
"content": "I'll just echo everyone's advice. This is a good place to learn or reinforce how to implement Ohm's Law.V = IRVoltage across the resistor is equal to Vsource (voltage of however you drive it) minus Vled (Usually listed a Vf in LED specs). You will also need If for the LED, the current required to turn it on.Using Ohm's:R = (Vsource - Vled) / IledNow, it will be important to also make sure the resistor you want to use is rated properly for the power.P = IV = (Vsource - Vled) * IledIf this comes out 0.5W and you try to put a 1/4 W resistor in there, you will make a nice charred resistor.Edit: Jon must have pushed post just after I started typing..."
}
] |
2025-10-17T20:39:56.709555
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10k-potentiemeter-connections/
|
10k potentiemeter connections - Page 1
|
[
{
"post_id": "",
"author": "RobH",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 01, 2020, 05:31:11 pm",
"content": "On other simple circuits which have included a 555 ic, I have connected the middle pin of the 10k pot to pin 2 on the 555ic.while the 2 outer pins are connected to +V and -VOn this schematic it shows a 1k resistor connected to pin 1 on the 3 pin 10k pot, then shows pins 2 and 3 connected, and then pin 3 to +5V.In practice, what should be the actual connections, as I'm a bit confused.Thanks"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 01, 2020, 05:59:18 pm",
"content": "The circuit you posted uses the potentiometer connected as a variable resistor in series with the fixed resistor in the timing circuit.Your previous connections used the part as an actual potentiometer to apply a variable voltage to pin 2."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 01, 2020, 05:59:50 pm",
"content": "The term \"potentiometer\" implies your first description of your circuit.The schematic shows a potentiometer connected as a variable resistor, which is not the same function (but the same device)."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 01, 2020, 06:00:40 pm",
"content": "Jeez, TimFox, we should start a club"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 01, 2020, 06:40:13 pm",
"content": "Great minds think alike, yet fools seldom differ..."
},
{
"post_id": "",
"author": "RobH",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 01, 2020, 06:41:01 pm",
"content": "Ok thanks but is the resistor connected to the middle pin of the pot, pin2, and then an outer pin to +V. Is that it, nothing else.Thanks"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 01, 2020, 06:57:19 pm",
"content": "When connecting a three-terminal potentiometer to make a two-terminal rheostat (q.v.), it is normal to connect the wiper to one end of the resistance element, to avoid momentary open-circuit high-resistance events if the contact be noisy."
},
{
"post_id": "",
"author": "RobH",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 01, 2020, 07:02:22 pm",
"content": "Thank you and that is how I have it connected. I just wanted to be sure when I asked my question.One other thing, is there anyway I can check that the circuit actually works, as this is the transmitter for a long range IR detector. I have built the receiver and that seems to work ok.I don't have any test equipment, apart from a multimeter.Thanks"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 02, 2020, 05:28:53 pm",
"content": "Quote from: RobH on December 01, 2020, 07:02:22 pm??The circuit in the OP is a receiver, isn't it?Anyhow, many cellphone cameras can see the light from many IR LEDs, so you could try looking at your transmitter's IR LED with your camera. Try both the front cam and the selfie cam."
},
{
"post_id": "",
"author": "RobH",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 02, 2020, 06:44:42 pm",
"content": "Yes the circuit is a receiver and has a TSOP 1838 IR Receiver .My phone, Huawei nova 5T, camera didn't pick anything up from it and the selfie camera , well, it was just me, lolIs there anywhere I could connect a LED. I've had a look round the circuit with a multimeter and the voltages are mostly 5v nominally.The relay I am using is a SPST with just 5 pins.Thanks"
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 02, 2020, 11:11:01 pm",
"content": "The phone camera trick won't work on IR receivers - just IR transmitters. (Works well - I've used this many times.)If you want to check if the receiver is picking up a signal, I'd probe the output pin of the receiver on a scope (assuming you have access to one)."
},
{
"post_id": "",
"author": "RobH",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 03, 2020, 09:26:27 am",
"content": "I tried my phone camera on the transmitter and , unless I was mistaken in some way, I saw what appeared on the led a small / tiny light blue dot near or at the top of the IR led. Or is that just the reflection of the camera??No I don't have access to a scope at all, and don't know anyone who has one.I fear I might have bitten off more than I can chew with this project / circuit.Thanks"
}
] |
2025-10-17T17:38:07.291967
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10k-potentiometer-fast-question/
|
10k Potentiometer fast question - Page 1
|
[
{
"post_id": "",
"author": "Dellyjoe",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 25, 2013, 05:36:35 pm",
"content": "hello everyone im just about done my project i have two things to wire up and i don't know which two are the cold and which one is the hot.i know for photometers you have two cold and one hot.here is the data sheet that i found but it doesn't tell me anything.http://octopart.com/datasheet/evu-e2af25d14-panasonic+-+ecg-573536-13329483i have # 3"
},
{
"post_id": "",
"author": "Galaxyrise",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 25, 2013, 05:53:44 pm",
"content": "resistors like that do not have a polarity"
},
{
"post_id": "",
"author": "Dellyjoe",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 25, 2013, 05:56:01 pm",
"content": "Quote from: Galaxyrise on June 25, 2013, 05:53:44 pmwow i feel sillythanks for the info"
},
{
"post_id": "",
"author": "Mr Smiley",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 25, 2013, 06:04:46 pm",
"content": "Centre pin will be the wiperIf you want increasing Vout (centre pin) moving in a clockwise direction, looking from the front, Vlow goes to the left pin, Vout ( with respect to the left pin, Vlow ) comes from the middle pin and Vhigh goes to the right pinIf you want decreasing Vout (centre pin) moving in a clockwise direction, looking from the front, Vhigh goes to the left pin, Vout ( with respect to the left pin. Vhigh ) comes from the middle pin and Vlow goes to the right pin"
},
{
"post_id": "",
"author": "Dellyjoe",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 26, 2013, 01:33:02 pm",
"content": "Quote from: Mr Smiley on June 25, 2013, 06:04:46 pmThank you Mr smiley i found that out by playing around with it, but thanks again for letting me know if i didn't do that"
}
] |
2025-10-17T20:20:28.941899
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10khz-to-2mhz-1mw-to-1w-amplifier/
|
10kHz to 2MHz , 0.25mW to 150mW amplifier - Page 1
|
[
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 17, 2018, 04:53:56 pm",
"content": "Hi all,I need the following amplification:INPUT:frequency range = 10 kHz - 2MHzV = 1 V peak-2-peakI = 1-2 mA peak-2-peakOUTPUT:Vo = 12 V peak-2-peakIo = 80-100 mAPower = 30 dBm (about 1W)Does something like this exist that I can buy? Or I can also build one, but what basic component do I need? Would an OpAmp do the trick?Also, if the bandwidth is too large for the amplification that I need I can split the amplification in 2 (max 3) sub-amplifiers, each covering a sub range of frequencies, this is not an issue.Thank you"
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 17, 2018, 08:24:46 pm",
"content": "ADSL line driver or two plus a transformer or Balun?Linear or TI spring to mind for some reason.Regards, Dan."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 17, 2018, 09:44:20 pm",
"content": "FYI, ADSL drivers are apparently really quirky, don't use them outside the range that ADSL needs (even if the specs say or imply they can run over a normal op-amp sort of range). Maybe okay here.A modestly fast line-driving-capable op-amp or buffer should do fine here. Shouldn't have trouble finding one off the shelf.Possible gotchas: supply voltage range, slew rate, distortion, RMS output, load impedance (resistive? complex? nonlinear?), transient ratings if any, passband flatness, cutoff band slope, etc.Reminds me of something I breadboarded years ago,You might want something more powerful than '390x's for output, for which you might use some SOT-89 BJTs instead, which will get you plenty of dissipation into a copper pour, for 1W output. Or a TO-126 something or other if you prefer THT.A discrete solution should be a rather extreme measure, for something that ought to be commercially available, so this is just FYI.Tim"
},
{
"post_id": "",
"author": "Cerebus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 17, 2018, 10:33:07 pm",
"content": "Tim, nine transistors? Two too many surely?As to the OP's problem, Jim Williams' Linear application note 47 has a couple of handfuls of useful designs that will meet your spec and a lot of relevant tutorial material. Now on Analog's website:http://www.analog.com/media/en/technical-documentation/application-notes/an47fa.pdf."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 17, 2018, 10:41:23 pm",
"content": "Quote from: Cerebus on April 17, 2018, 10:33:07 pmAlas, t'was before 7TL's time (I said it was old).It could... ehhhh... let's see:- The one current mirror could be a resistor and transistor, simple enough. Worse offset, who cares right?- The diff pair tail could be a resistor. This impairs common mode range, but that would be acceptable for modest-gain and inverting applications.Ahh... that feels betterTim"
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 17, 2018, 11:07:41 pm",
"content": "An HP 465A is pretty close to what you want: 5Hz-1MHz, 0.5WThey are not hard to find on eBay."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2018, 07:54:23 am",
"content": "Quote from: raff5184 on April 17, 2018, 04:53:56 pmYou've made a an error with your power calculation.12Vpp = 6V peak.Assuming you meant a current of 100mA peak, not RMS, that's a peak power of 0.1*6 = 0.6W and the RMS power of a sine wave is half the peak, so 0.3WRMS. If you meant 100mARMS, then multiply by 20.5."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 18, 2018, 08:40:14 pm",
"content": "thank you all. Sorry there was a mistake in the specifications.It is not 30dBm, I meant that I want a gain of30dB.IN power = 0.125mWOUT power = 150 mWhence, gain = 30dB."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 18, 2018, 08:48:28 pm",
"content": "The correct requirements are:INPUT:frequency range = 10 kHz - 2MHzV = 1 V peak-2-peakI = 1-2 mA peak-2-peakIn Power = about 0.250 mWOUTPUT:Vo = 12 V peak-2-peakIo = 80-100 mAOut power = 150mW (or more)amplifier gain = 30dB (or more)"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2018, 10:59:27 am",
"content": "Your specification is still contradictory.1V peak to peak (not peak-2-peak) which is 0.5V peak, P = (Vp*I)/2 = (0.5*0.002)/2 = 0.0005 = 0.5mW.Are you talking about power or voltage gain?If the input power is 0.5mW and output 150mW, that's a power gain of: A = 150/0.5 = 300 = 10*log(300) = 57dBIf you're talking about voltage gain then: AV= 12/1 = 12 = 20*log(12) = 21.58dBThe voltages are clear, Vinpeak= 0.5V & Voutpeak= 6V. Now what about the input and output impedances?I think a video amplifier IC is more than adequate for this task."
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2018, 03:33:20 pm",
"content": "You sure?0.5mW in 150mW out, so A = 300 times.300 times power in dB is 10 log(300) = ~25dB, I have no idea where you got 57dB from.Yea, current feedback opamp or something of the sort, but notice that the source impedance seems to be quite high, so something fast and voltage feedback may be a better choice. Either way, not hard.Regards, Dan."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 20, 2018, 08:01:45 am",
"content": "Quote from: dmills on April 19, 2018, 03:33:20 pmMy mistake. I used the wrong log function. I pressed loge, rather than log10.QuoteYes, a high speed op-amp my do, although it may be a bit more expensive, than a video amp IC, but I haven't looked at this for a long time."
}
] |
2025-10-17T18:33:58.785585
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10kv-1a-rectifier-can_t-be-made-from-just-1n4007_s-can-it/
|
10KV 1A rectifier can't be made from just 1N4007's, can it? - Page 1
|
[
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "August 18, 2017, 12:29:41 am",
"content": "Digikey shows 1 amp Semtech devices weighing-in at $200 each. So this advice is just a setup for cascade failure, right?"
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "August 18, 2017, 01:13:18 am",
"content": "As a half-wave rectifier, I made the assumption (yes I know what they can do..) that immediately after conduction the last anode would briefly be at 9*Vf due to junction capacitance of the first 9 diodes and this would start cascade breakdown.So reverse leakage negates that and causes all 10 to share Vr equivalent to the whole stack.Also, would the slew-rate of higher AC frequencies (say 1Khz, not 50/60 hz) give any cause to de-rate Vr for the stack?"
},
{
"post_id": "",
"author": "digsys",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 18, 2017, 01:26:50 am",
"content": "It is very common (and recommended) practice, to put equalization resistors across each diode. Usually 100-330K, depending on diode specs.\"rated to conduct say 10x the worst-case reverse leakage current across the volt/temperature range. Otherwise one diode leaks, and the other breaks down\"In some designs in the long past, we even added 10-20pF across them as well. This will keep all didoes closely matched in all conditions."
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "August 18, 2017, 01:52:16 am",
"content": "So would the extra resistors and caps likely be found inside the $200 Semtech part (for longevity or stability)?**edit -Also even with a higher 470k across each part in the stack, 21-watts at 10Kv seems like a lot to loose (say, when running a generator and boost transformer to charge some oil capacitor bank)."
},
{
"post_id": "",
"author": "Jay_Diddy_B",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 18, 2017, 02:10:18 am",
"content": "Hi,You might want to look at the diodes switching characteristics, Trr and Qrr, if you are using the part at frequencies higher than a few hundred kilohertz.If the application is low current, you want to look at junction capacitance as well.Regards,Jay_Diddy_B"
},
{
"post_id": "",
"author": "Circlotron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 18, 2017, 02:50:37 am",
"content": "$200 sounds a lot for 10kV 1A.http://hvstuff.com/1a-10kv-high-voltage-diode-hv-rectifier-tesla-coil-hamI've bought some of their 40kV 1A and 80kV 200mA diode stacks with acceptable results."
},
{
"post_id": "",
"author": "Beamin",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 18, 2017, 05:50:26 am",
"content": "Quote from: Cliff Matthews on August 18, 2017, 01:13:18 amAssumptions can give you \"sum pastion\".So when they are in series say 10; each one drops .6v for a total of 6 volts drop? Will they work like resistors if you put ten in series and powered a 3v led off 9 volts? Or would this blow up the led? That always confused me how diodes will lose straight .6 volts always but resistors voltage drop is based on current *and* voltage. Do they get hot when losing this .6 volts? How much current does the diode use? Can you measure ohms across it?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 18, 2017, 07:46:18 am",
"content": "How about a microwave oven diode? They're not usually rated to 1A though, usually a few hundred mA.https://www.eevblog.com/forum/beginners/circuit-with-op-amp-lm339/?action=dlattach;attach=190287;imagehttp://hvstuff.com/12kv-350ma-microwave-oven-high-voltage-diode-rectifier"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 18, 2017, 08:33:38 am",
"content": "When putting the 1N4007 close together like in the 1st picture, this will impede heat removal. So it might withstand 10 kV, but no more 1 A rating. I have seen 1N4007 in series been used at 40 kV (though less than 1 A).Fast transients and thus reverse recovery currents could be a problem though, as in this case voltage sharing might no work well. At least it would be a good idea to have diodes from the same batch in this case, to have a close match in t_rr. Depending on the application one might want to have added capacitors or fast diodes."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 19, 2017, 02:25:10 am",
"content": "You can definitely do it with 1N4007s but the diode of choice would be some type of avalanche rated rectifier which will not require leakage current and capacitance balancing. If it was handy, I would take a photograph and post it but I have a rectifier made this way which is like 3 feet long made from DO-4 packaged stud rectifiers on printed circuit boards sandwiched between fiberglass U-beams that is 10+ kilovolts at several amps."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 19, 2017, 05:41:05 am",
"content": "The original TV high voltage rectifiers were just a stack of selenium discs placed in a tube, with a spring one end to provide contact pressure, and for decades all rectifiers were made from stacked rectifiers, either copper oxide or selenium, with a spring to provide clamping pressure.Known to work, though I would for high voltage work buy a reel of diodes so all are at least from the same die, and derate them voltage wise to around half the rated, using more diodes. With the 1N4007 however they are very likely to be able to withstand 2000V, though this is not tested, they are only rated to withstand 1200V as this is tested during manufacture to bin them."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 19, 2017, 06:17:35 am",
"content": "Two things not well noted yet in this thread:1. Reverse recovery.2. Matching.Indeed, all EHV diodes are stacks. It's possible to make single junctions up to 6kV or so; recovery time is quite slow, though. (Example:http://www.vishay.com/docs/93177/vs-sd553cs50lseries.pdfnote that 6us really is fast (compare 1N4007 at ~3us), for a diode of this voltage!) For both these reasons, a practical diode of, say, 10 or 20kV might be made of a half dozen dies, stacked.Matching is critical, and that's why they make proper stacks.At mains frequency, as mentioned above: recovery doesn't matter much, and the avalanche rating will take up the difference okay. 100k range resistors will do a good job of balancing the DC reverse voltage, by swamping the leakage currents (which won't match even under the best of circumstances).But as you go up in frequency, recovery-related losses (i.e., the avalanche that accompanies the earliest recovering diodes) come to dominate. You can try swamping this with capacitors, but your application might not allow much of that, either!There's also dynamic recovery to worry about: this is better known (but still not very well known) with higher voltage BJTs, but it applies to diodes as well! The physics is this: the junction does not recover uniformly, but rather it's more that the charge sweeps out, like a bucket drains through a hole in the bottom: as the level falls, the surface stays parallel. That means the junction width, and therefore the instantaneous breakdown voltage, rises over time, until the charge is empty and it settles out to the normal value.(When you see a \"soft recovery\" diode, it means that the recovery process has been tuned, for a particular setup condition (a few microseconds forward bias, then a modest dI/dt reverse recovery), to give a controlled breakdown voltage, causing the voltage to rise smoothly. Soft recovery costs more dissipation than an otherwise-identical diode made to be as fast as possible, but produces much less EMI. The difference might be, say, 20ns for a \"ultrafast recovery\" part, versus 40 or 50ns for a \"soft recovery\" part. Not a big deal at most switching frequencies.)So the problem is that, the whole time a diode is becoming open circuit (during the voltage rise), it's burning power. And that voltage is clamped to a value that rises as recovery finishes, up to the rated voltage eventually. If you have diodes that have mismatched recovery times, in an application that is fast enough to be recovery limited: you're in for unhappy diodes.What the manufacturers can do, then, is select dies by recovery time and charge, and junction capacitance, and use matched parts in the stacks.Tim (has melted UF4007s by connecting just two in series and operating at 100kHz)"
},
{
"post_id": "",
"author": "Beamin",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 23, 2017, 03:34:25 pm",
"content": "Quote from: Hero999 on August 18, 2017, 07:46:18 amThe proper part only costs 2.15$? Why not just buy that? I was thinking it was some obscure hard to get expensive part."
}
] |
2025-10-17T18:48:17.582747
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10mm-led-bulbs/
|
10mm LED Bulbs - Page 1
|
[
{
"post_id": "",
"author": "justintime2001",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 05, 2015, 05:54:25 pm",
"content": "I am trying to replace 2 flashing LED's in a bait boat. I wanted to replace them with constant LED's but they blow as soon as connected. I have managed to fit 2 new flashing LED's but these dont flash as such they stay on but sort of swap from dim to brighter rather than actually flash. Can anyone please advise or point me in the right direction? They are 12 volt LED's and the boat runs on a 12V 10Ah battery."
},
{
"post_id": "",
"author": "LA7SJA",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 05, 2015, 07:20:31 pm",
"content": "You must connect a current limiting resistor in series with the LED, use a value of 4700 Ohm (bright) to 10000 Ohm (dim). This shuld give the LED 25 to 1mA with most LED's. The \"flashing\" LED's have build in electronics for 12V suply.Johan-Fredrik"
},
{
"post_id": "",
"author": "justintime2001",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 05, 2015, 08:21:43 pm",
"content": "Thank you Johan,Does this mean a resistor before each LED or one for all of them? Could the lack of resistor be why constant LED's are blowing? Thank you.image attached"
},
{
"post_id": "",
"author": "tec5c",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 05, 2015, 08:57:17 pm",
"content": "If that is how you initially wired them (without the resistors) then you replaced them in backwards. The longer leg is (almost always) the positive leg.Flip them around and connect them up with the resistors (like the diagram shows) and you should be fine."
},
{
"post_id": "",
"author": "justintime2001",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 05, 2015, 09:17:02 pm",
"content": "Brilliant, thank you."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 05, 2015, 09:44:26 pm",
"content": "As an observation, if you connec several leds in series like you show in the picture, you only need ONE resistor at one end of the chain to limit the current going through all the leds.The current going through the leds can be determined using the formula Current (in amps) = ( Battery Voltage - number of leds x forward voltage of one led ) / Resistor value in ohms"
},
{
"post_id": "",
"author": "tec5c",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 05, 2015, 10:08:52 pm",
"content": "My mistake, I was in a hurry.I initially thought that the diagram showed the LEDs connected in parallel. On second look, what mariush suggested is a more suitable approach."
},
{
"post_id": "",
"author": "justintime2001",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 06, 2015, 12:46:57 am",
"content": "Thanks guys. The boat actually appears to be wired like the diagram below, but possibly without all the resistors. Hope it makes sense?"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2015, 02:05:50 am",
"content": "No, that's really not right.Go here :http://www.falstad.com/circuit/then click on File > Import from text and paste the following (make sure you select all, watch the scroll bar):Code:$ 1 5.0E-6 10.20027730826997 50 5.0 43v 112 352 224 352 0 0 40.0 -12.0 0.0 0.0 0.5162 128 64 208 64 1 2.1024259 1.0 0.0 0.0162 240 64 320 64 1 2.1024259 1.0 0.0 0.0162 384 64 464 64 1 2.1024259 1.0 0.0 0.0162 512 64 592 64 1 2.1024259 1.0 0.0 0.0r 96 192 176 192 0 100.0r 272 192 352 192 0 100.0r 480 144 576 144 0 100.0r 624 144 704 144 0 100.0w 224 352 208 64 0w 128 64 176 192 0w 96 192 112 352 0w 240 64 272 192 0w 384 64 480 144 0w 512 64 624 144 0w 224 352 416 352 0w 416 352 320 64 0w 352 192 352 240 0w 352 240 176 192 0w 112 352 112 400 0w 112 400 736 400 0w 736 400 704 144 0w 592 64 608 352 0w 608 352 416 352 0w 624 144 576 144 0w 464 64 416 352 0w 480 144 352 192 0o 1 64 0 35 2.5 0.2 0 -1o 2 64 0 35 5.0 0.0125 1 -1o 3 64 0 35 5.0 0.1 2 -1o 4 64 0 35 5.0 0.2 3 -1It will simulate the circuit your drew in the picture, only the components are arranged in a much uglier way. You can move mouse over the oscilloscope drawings at the bottom to see how much current goes through each led.Basically some leds receive more current because they get energy through two resistors and one of the led will barely light up or won't light at all according to your schematic."
},
{
"post_id": "",
"author": "justintime2001",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 06, 2015, 10:44:15 am",
"content": "Thank you mariush, It is how the boat is wired up at present. It's like a ring main in the uk. I will rewire the whole thing I think just how you guys have said."
},
{
"post_id": "",
"author": "justintime2001",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 07, 2015, 12:52:23 pm",
"content": "Hi Guys,I just wanted to let you know that I have rewired the boats lighting following your guidance and it has worked a treat.It may be simple to the experts but for me it was an achievement, so a big thank you for your help.All the best, Ian."
}
] |
2025-10-17T19:32:28.645313
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10uf-35v-decoupling-capacitor-alternative/
|
10uF 35V decoupling capacitor alternative - Page 1
|
[
{
"post_id": "",
"author": "Aykut1",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 29, 2025, 11:59:07 am",
"content": "Hi, I have designed my first PCB, which includes 10uF 35V decoupling capacitors close to the 5V, +5V, +3.3V, and 30V sources. However, I was unable to find this SMD component anywhere near my area, and ordering is taking a lot of time. Is there any other value I can replace this component with? I know the basic working principle of a decoupling capacitor, but I am not sure how does the value range of the component affects. I would appreciate it if anyone can recommend alternative values and also explains how can the range of it is determined or calculated. If it depends on the system I can also share my schematics and design. Thank you!"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 12:04:35 pm",
"content": "What sort of capacitor is it: ceramic, aluminum electrolytic, tantalum?10µF is a very common value, but for decoupling it's unimportant, although higher is generally better: 15µ, 22µF will be fine. Always go for a higher voltage rating than the voltage rail, especially for tantalum which might need to be double theNote that ceramic capacitors have a saturation effect, like inductors, meaning their capacitance decreases, as the voltage is increased, so you might need to use a much higher voltage rating and value, to achieve the required capacitance."
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 12:41:36 pm",
"content": "Use 10uF 50V that should be easy to find."
},
{
"post_id": "",
"author": "PGPG",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 12:42:26 pm",
"content": "Quote from: Aykut1 on July 29, 2025, 11:59:07 amI don't understand English word 'decoupling' perfectly. For me decoupling capacitors are 100nF I locate as close as possible to IC supply pins.At PCB supply inputs electrolytic capacitor are frequently used. Even mostly I use SMD elements for these capacitors I select THT parts.A practical rule for electrolytic capacitors is that their nominal voltage should be 2x their maximum working voltage.So for -5V and 5V you should use capacitor with at least 10V nominal voltage, but for 30V I would use at least 60V capacitor.Big capacitance (like 470uF, or more) is needed when capacitor is used to keep voltage between charging pulses coming from rectified AC 50Hz input. If supply voltage is already stabilized you can use only small (like your 10uF) capacitors."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 01:06:47 pm",
"content": "Quote from: PGPG on July 29, 2025, 12:42:26 pmThose are both examples of decoupling capacitors.QuoteYou don't need to go as high as double the supply voltage for aluminium electrolytic capacitors, on a regulated power supply, unless the temperature is high. 6.3V is fine on 5V logic rails. Tantalum yes, but aluminium is fine with a 10% or so margin.For smoothing capacitors, on a bridge rectifier connected to the secondary of a transformer, you want the capacitor to be rated to at least the maximum peak voltage. The maximum RMS voltage you can expect is the nominal unloaded secondary voltage plus 10% or so, to account for the tolerance of the mains voltage. If the unloaded secondary voltage isn't specified, then the data sheet often gives the regulation factor, a percentage which you need to add on to the secondary voltage to get the unloaded voltage. If this isn't available, then look at other transformers with similar power ratings and make an estimation.For example:12V transformer, 25% regulation factor.VRMSMAX= 12×1.30×1.10 = 17.2VThe capacitor needs to handle the peak voltageVPEAK= VRMS√2 = 24.3VSo a 25V capacitor will so, considering there will be some diode voltage drop and it's not going to be exposed to this voltage continuously. As always keep the capacitors away from the heat sink. By all means consider a higher voltage if there's room, but higher temperature rating is more important, than voltage."
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 10:02:04 pm",
"content": "Quote from: PGPG on July 29, 2025, 12:42:26 pmA decoupling capacitor can mean powersupply smoothing capacitor, or AC bypass cap.Decoupling is used for it's dictionary definition. To separate, disengage, or dissociate one thing from another.It can be disengaging the powersupply noise. Usually 100nF or 1uF, but can be 10uF too.Or separating the AC part of a signal from the DC part."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 10:13:39 pm",
"content": "I thought the kind of decoupling caps the OP is writing about are generally 0.1μF or so, not tens of μF.At least that's what I've always read. You know, the caps you're supposed to put next to pretty much every IC, between Vcc (or Vdd) and ground, to protect the chips from supply spikes and other crap.Why such large values here?"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 10:30:15 pm",
"content": "I agree about using 100 nF for “decoupling”, which I interpret as reducing the effect on the Vcc of U2 from current variations/spikes in U1, so you place them close to each Vcc pin of U1 and U2 .“Smoothing”, usually several uF, is used to reduce the ripple on the Vcc rail from the source of Vcc; another term is “reservoir” capacitance, especially for a single huge capacitor on each board.I am sometimes criticized for making careful distinctions in terminology instead of calling every part by the same term.Of course, decoupling capacitors must have very short traces or wires to each device.In higher impedance (high voltage, low current) circuits such as multi-stage tube amplifiers, it was common to insert a reasonable resistor (sometimes inductor) from the device/decoupling capacitor node to the supply rail to improve the decoupling effect, but that is impractical for IC power at 5 V or lower."
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 10:34:49 pm",
"content": "You can decouple the powersupply rail for an IC by placing a 100nF near that IC.You can also decouple your entire PCB from its external power source by putting 10uF/100uF/1000uF caps at the DC input to your PCB. Often we might call this bulk capacitance, but you are really just decoupling the power on your PCB from the external power source.Same concept but the scale/scope is different."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 10:44:22 pm",
"content": "Quote from: TimFox on July 29, 2025, 10:30:15 pmI think in this case you're perfectly justified in taking care in terminology.Quite helpful, actually."
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 10:49:56 pm",
"content": "I agree that it's always better to avoid using the words decoupling capacitor as a catch all term. Better to save decoupling cap for the rail caps near ICs and use 'bulk capacitance' or 'AC bypass cap' for other cap usage.I was just trying to help PGPG understand that 'decoupling capacitor' can have a pretty wide meaning and that's something to be aware of."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 11:07:48 pm",
"content": "When choosing a decoupling capacitor, it is useful to consider the current in each device and its likely variations and frequency. 100 nF is typical for a small digital IC. Similarly, a smoothing capacitor depends on the power supply ripple frequency, and lower-frequency components of the total circuit current draw."
},
{
"post_id": "",
"author": "PGPG",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 11:22:28 pm",
"content": "Quote from: Zero999 on July 29, 2025, 01:06:47 pm12V transformer primary coil have to be supplied by something - typically AC mains. At AC mains surges happen from time to time. These are the moments when having nominal voltage 2x higher than calculated peak voltage will be helpful."
},
{
"post_id": "",
"author": "Analog Kid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 29, 2025, 11:35:10 pm",
"content": "Quote from: PGPG on July 29, 2025, 11:22:28 pmI don't think those surges are likely to be 2X the line voltage.And if they were, they'd be of such short duration as to not be a problem.So I think 2X capacitor voltages are overkill. As most other folks also seem to think."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2025, 07:19:46 am",
"content": "Quote from: PGPG on July 29, 2025, 11:22:28 pmElectrolytic capacitors handle short term over voltages fine. The impedance of the transformer (leakage inductance and resistance) also help to limit the spikes.Open up any 230V mains powered switched mode power supply and you'll find it doesn't have 2×230√2 = 650V capacitors: 400V is the most common rating, occasionally 450V. Perhaps 650V is common in 400V three phase power supplies, but I've never opened one up and wouldn't be surprised if two lower voltage capacitors are connected in series."
},
{
"post_id": "",
"author": "PGPG",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 30, 2025, 11:04:35 am",
"content": "Quote from: Analog Kid on July 29, 2025, 11:35:10 pmYou are right. They are not 2x.They are much higher and limited to 2x by protecting elements.One of EMC tests each AC 230V powered device offered at marked have to pass is Surge test. The device get at AC230 supply a serie of 1kV surge pulses of internal resistance 1.2 ohm (if remember well).Pulse shape (rise time/fall time) is standardized.1kV is the minimum value used for devices destined to home use. For industrial devices higher pulse levels are used.Don't think of short times when supply voltage is little higher but of pulses that happen when lightning strikes nearby.Quote from: Zero999 on July 30, 2025, 07:19:46 amRight. In one Chinese supply I opened recently there was 450V input capacitor.At 12V supply I assume up to 15V (accumulator when charged get higher voltage than 12V).So to protect input I use transil that not conduct at 15V and starts conducting at 18V.You can check:https://www.st.com/resource/en/datasheet/sm6t100a.pdfthat for SM6T18A Vcl for 1000/10us pulse is 25.2V (after diode I have at input it gives 24.5V)So I assume that at 12V supply I can use 25V electrolytic capacitor.I have never designed protection for AC230 input. May be you are able to limit voltage to less than 2x working voltage so you use 450V capacitor."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 30, 2025, 01:36:03 pm",
"content": "Quote from: PGPG on July 30, 2025, 11:04:35 amI haven't designed a PSU with 230V input, but I've seen plenty of schematics and hardware. Many of them don't have MOVs or protection diodes across the capacitors and most of them use 400V capacitors. There are occasions when the capacitors blow up, but more often than not, it's the switching transistors which are destroyed by voltage spikes. Electrolytic capacitors rarely fail due to voltage spikes. They're self-healing; if the oxide is damaged by a voltage spike, it will re reform, as the bit of aluminium oxidises. Electrolytics generally fail due to high temperatures, too higher ripple current, or are just cheap/fake rubbish.If you want to design for long life, then you're generally better off going for higher temperature rating and higher ripple current, than higher voltage. Perhaps it's because higher voltage parts generally are bigger, thus have a higher ripple current rating, which is why the x2 voltage rating myth exists? Maybe it works in practice, up to a couple of hundred volts, but electrolytic capacitors with voltage ratings above 500V are less common, so it becomes impractical. Anyway, it's better to look at specifications which directly will result in longer life and a more robust product, rather than just over-rating the voltage, because it normally has the side effect of the capacitor having a higher ripple current rating."
}
] |
2025-10-17T16:15:43.491049
| 17
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10uf-cap-measures-6-2-7uf-normal/
|
10uF cap measures 6.2-7uF - Normal ? - Page 1
|
[
{
"post_id": "",
"author": "Signal32",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 28, 2021, 05:45:16 am",
"content": "Hello,Ordered a bunch of 0402 10uF/10V capacitors from AliExpress. These ones: .Measuring them with my U6-61E they come up at 6.1-7.1uF. The tolerance spec says +/- 20%, so I would expect them to measure in at at least 8uF.The multimeter seems good, measuring other caps you get exactly the values that you would expect. Ex: 2.19uF for 2.2uF, 0.99uF for 1uF, etc ....Is this normal / expected with smaller caps such as this ? Is this just a bad batch ?Thanks !"
},
{
"post_id": "",
"author": "Chalcogenide",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 06:02:22 am",
"content": "MLCCs suffer of a very strong DC bias dependence on the capacitance value. That specific part number is already 60% low at just 2V of applied voltage!http://weblib.samsungsem.com/mlcc/mlcc-ec-data-sheet.do?partNumber=CL05A106MP5NRN. Portable DMMs typically measure the time required to charge the capacitor to a given voltage to compute its capacitance, but this means that an MLCC suffering of DC bias effect will read low, and your part appears to be really quite bad in this regard."
},
{
"post_id": "",
"author": "The Electrician",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 06:08:12 am",
"content": "Quote from: Signal32 on September 28, 2021, 05:45:16 amWatch this:https://www.eevblog.com/forum/projects/mlcc-capacitors-and-my-experiments-of-dc-bias-on-capacitance/msg2601327/#msg2601327You shouldn't be using a multimeter to measure capacitors (particularly ceramic caps)--use an LCR meter (and for measuring ceramic caps the meter should have an ALC mode)."
},
{
"post_id": "",
"author": "Signal32",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 28, 2021, 06:36:07 am",
"content": "Makes sense, thanks !"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 08:48:42 am",
"content": "10uF is a very large value for an 0402 package. I would expect that it would have 'compromises' several areas, including pretty extreme voltage coefficient, as you have found. I doubt the Ali ones would have as close a tolerance as the Digikey ones you referenced either, I wouldn't be at all surprised at -50%."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 28, 2021, 09:02:36 am",
"content": "There is such thing as capacitance aging. Capacitors made with type 2 and 3 ceramics start losing their capacitance since the moment they are produced. Heating during reflow resets the process, capacitance is regained and starts dropping again. Considering that capacitors stayed on shelf quite a while, measured capacitance seems reasonable for 10uF cap. You can heat it again with hot air or soldering iron, let it cool and measure again.If capacitor uses type 3 ceramic, like Z5U or Y5V, then you will also have strong temperature dependence. Just a heat from your fingers may cause a significant portion of the capacitance to be lost.Capacitance voltage dependence should not cause much of measurement difference unless your meter causes significant DC bias."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 28, 2021, 09:12:24 am",
"content": "PDF about ageing process."
},
{
"post_id": "",
"author": "RoGeorge",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 09:56:09 am",
"content": "Quote from: wraper on September 28, 2021, 09:12:24 amI didn't know that, thank you!Quote"
},
{
"post_id": "",
"author": "Vovk_Z",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 04:49:37 pm",
"content": "Quote from: Signal32 on September 28, 2021, 05:45:16 amIf you want 'real' 10 uF you should buy at least 1210 size ones (X7R, but not Y5V)."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 05:07:52 pm",
"content": "When dealing with the inherent properties of a dielectric in a capacitor (or a non-linear conductor in a resistor), the independent variable is the E field (voltage gradient), so the non-linearity will be worse in smaller packages (for a given applied voltage across the terminals)."
},
{
"post_id": "",
"author": "dietert1",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 05:39:16 pm",
"content": "I have seen exactly the same -30 % low capacitance with MLCC. It's strongly temperature dependent.If you want a capacitor with +/- 10% or +/- 5 % tolerance, it's a film cap.Regards, Dieter"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2021, 08:43:32 pm",
"content": "10 µF in 0402 size is rediculous small. Don't expect more miracles from such a small part.The Class 2/3 ceramics have rather non ideal properties. When needing a more ideal capacitor, more modern C0G ceramic caps are a real alternative to film caps, though only for smaller values (e.g. < 50 nF). Even in a relatively small package C0G can be pretty good, with low leakage and low loss."
},
{
"post_id": "",
"author": "bobbydazzler",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 12:47:53 pm",
"content": "Yes the smaller the package the worse the capacitor is affected by dc bias. Also they're from Alixpress so may not even be genuine x5r parts, they could be y5v. I got some 47uf 'x7r' 1210 mlcc capacitors from ebay that seemed to be genuinely 47uf but as soon as they warmed up they had almost no capacitance, so probably y5v or worse."
},
{
"post_id": "",
"author": "The Electrician",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 03:03:55 pm",
"content": "Quote from: wraper on September 28, 2021, 09:02:36 amEven without DC Bias, the measurement difference can be quite large depending on the value of the AC excitation voltage applied by an LCR meter. See the graph labeled \"AC voltage characteristics\" in this spec sheet:http://weblib.samsungsem.com/mlcc/mlcc-ec-data-sheet.do?partNumber=CL05A106MP5NRNAlso see this video:"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 04:07:00 pm",
"content": "With such a nonlinear part, does it still make sense to quote a capacitance for this. If nearly looks like this is more like a square hysteresis curve.Getting the capacitance down nby 60% when measuring with a very low AC voltage is a really odd point. So the capacitance is no the small signal capacitance, but rather specific for a given amplitude. Samsung uses 0.5 V in the DS and Kermet use 1 V - so not even the same standard.Maybe they should show hysteresis curves.With so nonlinear parts it can also matter how the meter is measuring (sine voltage or sine current) or doing the math."
},
{
"post_id": "",
"author": "dietert1",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 04:35:04 pm",
"content": "Like you wrote before it depends on the size. Just wired a 0805 4.7 uF MLCC and it reads 4.5 uF after soldering while still a bit warm and 4 uF at room temperature. This is with an old HP 4262A at 120 Hz, 10 Vrms idle, 370 mVrms on the cap. With higher test frequencies, where the remaining voltage gets smaller, it measures as low as 3 uF.In the past i measured 0805 10 uF MLCCs many times, always wondering why they measure about 7 uF at 120 Hz. So 0603 or 0402 should be much worse. A pitty the Kemet expert doesn't tell the size, anyway a good lesson.Regards, Dieter"
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 04:40:47 pm",
"content": "Remember there are a lot of bypass applications for low core voltages like just 0.8V, where a lot of capacitance is needed with small parasitic inductance, i.e., small package.If anything, ratedvoltageis to be taken with grain of salt. It's guaranteed not to \"blow up\" at 10V. For useful capacitance, that is, near rated 10uF, this part is designed to bypass Vcore = 1.2V and less."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 05:52:21 pm",
"content": "There is a mature theory of non-linear electronics, where a non-linear capacitor is defined by its hysteresis and functional relationshipV(Q), which is notV=Q/C, in general.See M Hasler & J Neirynck \"Nonlinear Circuits\" (Artech House)."
},
{
"post_id": "",
"author": "dietert1",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 09:33:42 pm",
"content": "After testing a 4.7 uF MLCC i left the HP 4262 with 6 V DC on for several hours and when i happened to look again, capacitance measurement was a mere 1.2 uF! After turning off DC, measurement went up to 3 uF and appears stable or rising slowly. Parts are labeled: UMK212BBJ475KG-T (Multilayer Ceramic Capacitors MLCC - SMD/SMT 0805 50VDC 4.7uF 10% X5R) and their capacitance can be anywhere between 25 % and 100 % of nominal value. \"It depends.\"Regards, Dieter"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2021, 09:40:20 pm",
"content": "Following Siwastaja, the \"10 V\" rating is merely for safety, where the manufacturer guarantees the device can withstand 10 V without failure or excessive current. It is not a recommended operating voltage, but the details require knowledge of your own requirement and the datasheet curves."
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2021, 05:49:06 pm",
"content": "OTOH such 10V part may happily take 50V without blowing up in any way, ever. It just loses even more capacitance under that bias.MLCC voltage ratings are even more arbitrary than their capacitance ratings.My preferred method, when large amount of capacitance is required, is to find a few candidates, then look up actual capacitance under the applied voltage, then sort for $/uF to get the best deal. Rated capacitance or rated voltage are neither very useful here, they just offer starting points for sorting/finding. A 2.2uF part might offer 90% of the capacitance of the 4.7uF part on the same series, at half the price. I.e., both are roughly 1uF actual.Of course, if it's a professional job I won't use a part athigherthan rated voltage; for a prototype, I might, and have used some 25V rated parts for 30-something volt buses.With low-voltage MLCCs (like 25V and down), voltage derating is really not needed, if I have a 10V bus and a 10V part happens to offer good capacitance at 10V DC bias, I can use it, no need to go for a 16V part."
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2021, 06:04:26 pm",
"content": "All of the comments about why this measure low are related to measurement. The real question is how these parts will operate in your circuit. If your circuit operates down around two volts they don't meet your stated need. If they are operated at a significantly higher voltage they may. Component selection always involves many factors and trades.Whether the low reading justifies a return for credit is another whole question. Gets into what the data sheet says they will do vs what they are actually doing. If they are performing to data sheet, then it's your problem for not understanding what you are buying. The fact that you were misled by a simple value used to identify the part is irrelevant. If they don't you can try to get a refund, and an honest source will give it to you."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2021, 06:20:40 pm",
"content": "Using these caps with a relatively low voltage, like 2 V is normal, but the normal case is also to have a low ripple amplitude, usually way less than 0.5 or 1 V RMS. So in real world one would not see the nominal capacitance, but considerably less, even without the degradation from high DC."
}
] |
2025-10-17T17:21:58.502981
| 23
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10uf-tantalum-capcitor-adxl375/
|
10uf tantalum capcitor adxl375 - Page 1
|
[
{
"post_id": "",
"author": "Vindhyachal.takniki",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "January 20, 2015, 09:49:29 am",
"content": "1. Adxl375 specifically mentioned about using 10uf tantalum capacitor on Vs.2. What the reason for that?3. What if I use 10uf ceramic for that.I have read on internet thet ceramic has below drawbacks:1. Aging2. Voltage coeff3. Piezeo noise4. Flex crack (most severe)After reading I guess since adxl375 is used for measuring accelration so most dominating reason to use 10uF tantalum will be piezo noise. Is it right?But along with 10uF tantalum, datasheet specify to use 0.1uF ceramic also, which may go opposite to my above reason.I want to know what exactly the reason for using tantalum here."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 20, 2015, 08:58:21 pm",
"content": "Tantalum provides supply damping due to ESR. An acceptable substitute may be a ceramic capacitor of the same value, in series with a chip resistor of a few ohms (to replace the internal ESR of the tantalum).Exact values depend on what else is connected to the supply as well.Tim"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 21, 2015, 02:18:08 am",
"content": "Quote from: T3sl4co1l on January 20, 2015, 08:58:21 pmFew ohms would make it more like electrolytic cap ESR, not tantalum. Unless there is ceramic capacitor unfriendly LDO nearby to this capacitor (low track resistance), no issues with using ceramic as it is. If going to use Y5V or Z5U type, do not forget that they change capacitance drastically with temperature and applied voltage. X7R is far from ideal too, especially when applied voltage is more than half of rated, depends on actual capacitor model though."
}
] |
2025-10-17T19:48:52.516081
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10v-dc-voltage-reference-standard-what_s-wrong/
|
Voltage Reference - Page 1
|
[
{
"post_id": "",
"author": "Rafael",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 10, 2018, 06:23:10 pm",
"content": "Hello Voltnuts...Please, I got a 10V Voltage Reference Standard from eBay where the promise is+-2ppm.The seller guarantees that he is calibrated and is only blaming the humidity of the environment.Thanks a lot."
},
{
"post_id": "",
"author": "TiN",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2018, 06:53:58 pm",
"content": "Seller cannot guarantee you promised spec on that little box (have a read if you bored and have good sense of humor), but also you need keep both meters in high-impedance mode and 8846A might cause errors when connected together with other meter. You may want to have both meters connected one at a time. And anyway calibration performance even for freshly calibrated 34401 and 8846A is far worse than 2ppm.Nixie temp meter is slick."
},
{
"post_id": "",
"author": "glarsson",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 10, 2018, 06:57:44 pm",
"content": "Quote from: Rafael on March 10, 2018, 06:23:10 pmDid the seller promise an absolute accuracy of 2ppm, a drift per day/month/year of 2ppm or a drift of 2ppm per kelvin temperature change?"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2018, 07:05:01 pm",
"content": "There's no way a little black plastic box from eBay is going to match the performance of those expensive multimeters. I'd say the reading you are getting is not bad, considering..."
},
{
"post_id": "",
"author": "TiN",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2018, 07:13:26 pm",
"content": "Sorry, read the user manuals. They have good Info's. Its 3am here now"
},
{
"post_id": "",
"author": "2N3055",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 10, 2018, 11:29:02 pm",
"content": "There are few threads \"dedicated\" to this scam... for instance :https://www.eevblog.com/forum/metrology/calibratory-d-105-dc-precision-voltage-reference-standard/I'm afraid you got \"kaysered\"... You should have bought on of \"those small boxes of reference of china AD584H\"... They would be comparable in specs and much much cheaper...Also,http://www.voltagestandard.com/-.html] http://www.voltagestandard.com/-.html actually works as specified.... For much less money..."
},
{
"post_id": "",
"author": "MasterT",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 11, 2018, 01:22:45 am",
"content": "I wander, if X-ray screening at the custom /inspection station could be blamed. My google search on topic brings this doc :https://www.intersil.com/content/dam/Intersil/documents/an15/an1533.pdfDoes such issue exist with all highly priced metrology equipment, and how it could be avoided?"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 11, 2018, 10:24:21 am",
"content": "No, those Intersil references use charges stored on floating gate FETs as their reference. Very easy to produce custom voltages but very sensitive to Ionizing radiation, x-rays etc which drains the charge away - just like UV EPROMS.It's a very different mechanism to other references, to change the voltage of a buried zener would require very large amounts of radiation to damage the atomic structure of their junctions.EDIT: The problem with the OP's reference probablyishumidity - if you check back through the referenced threads about it, it uses an Epoxy packaged REF02 rather than hermetic, making it very humidity sensitive (at the level of precision involved). The claims about its accuracy took no account of that (though a few weasel words have now been added to the listing)."
}
] |
2025-10-17T18:36:23.743693
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10w-psu-no-ripple/
|
10W psu "no" ripple? - Page 1
|
[
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 08, 2021, 06:43:43 pm",
"content": "I am in need of a power supply with variable 0-10V and variable current max 1A.My need is the ability to adjust in +/- 0.1mA and as little ripple as sanely possible, maybe 0.1 uA / mV.My problem is that I do not feel I am capable of designing the circuit, and I haven't found anything usable.Is it sanely possible?"
},
{
"post_id": "",
"author": "MathWizard",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2021, 07:03:52 pm",
"content": "What sort of parts did u want to use, modern op-amps? or some older discrete design? I bet there are some pretty good old designs with schematics available, with low noise, but they also would have had all the parts matched just right, with all the spec's measured, etc, to really get low noise.IDK what/when would be the 1st PSU with the spec's you want, but I'd also like to make a low noise, low voltage PSU at some point.I'm just re-making an old Heathkit PSU, but with cheap parts. If it ends up close to the rated spec's I'll be happy,"
},
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 08, 2021, 09:33:39 pm",
"content": "I have no preference in components, but maybe SMD and chips is easiest? Old components may be hard for me to mach perfect."
},
{
"post_id": "",
"author": "Warhawk",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 08, 2021, 09:59:59 pm",
"content": "Quote from: FriedMule on July 08, 2021, 06:43:43 pmStart looking at LT1970 and its applications. This would be my first starting point."
},
{
"post_id": "",
"author": "xavier60",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2021, 10:48:07 pm",
"content": "It's usual for most PSU designs to have some output ripple in CC mode. I think it's due to the very low value of the current sense resistor causing the CC loop gain to be low.This can be fixed with an active ripple filter. It can be a Darlington Emitter follower with an RC filtered voltage applied to the Base that's a few volts lower than the unregulated supply."
},
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 09, 2021, 04:07:54 am",
"content": "Do you mean i.e. 12V transformer and then maybe 10V as output will surf ice?What frequency do you think the filter shall work in?"
},
{
"post_id": "",
"author": "xavier60",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2021, 08:48:15 am",
"content": "Because of the voltage drop across the active filter, say 4V, a 12VAC transformer might be cutting it close. Depending on its size.Do you already have transformers to try?Just the first part is applicable.The Emitter follower style filter works well with 100Hz ripple."
},
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 10, 2021, 12:06:17 am",
"content": "Thanks to you all did I find the following schematic, it sounds as a start point:Link to entire article:https://www.analog.com/en/technical-articles/high-performance-portable-dc-bench-power-supply.htmlI do not care if it can deliver above 10V or 1A, but ripple is paramount and fine adjustable. Could a 20+ turn pot be used?I do own an old 12V trafo but I'd rather buy a dedicated trafo for the project.EDIT: Saw the following text: \"Linear regulators at the output suppress output ripple without requiring large output capacitors, resulting in a truly flat DC output and small size. At full power, 10mF cap will produce about ±1V ripple on the 34V DC input.\"2V p/p in ripple for a 34V PSU, does not sound as \"truly flat\" :-)"
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 10, 2021, 01:32:07 am",
"content": "Off the wall idea,power the regulation circuit from a battery ,that gets charged when you switch the regulator off"
},
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 10, 2021, 02:09:08 am",
"content": "Yes that is a possibility, maybe a super cap or more could also do it?Build it as some sort of double-sided UPS where one side charges until it is empty and the \"UPS\" switch to the other side?"
},
{
"post_id": "",
"author": "xavier60",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 10, 2021, 03:35:00 am",
"content": "Quote from: FriedMule on July 10, 2021, 12:06:17 amI haven't put much thought into that design. If you want very fine current setting resolution, you also would want very stable setting accuracy, very little drift with temperature changes.I had hoped that you chose a simpler all linear design, keeping in mind what I said earlier.I just did a test on my most resent bench PSU project. It has 5mV p-p 100hz ripple while sourcing 1A into 10Ω.The CC loop can be bread-boarded using common components.The transformer I chose is medical grade with internal shield. I'm not certain how much it helps in reducing noise and ripple.https://au.mouser.com/datasheet/2/410/media-845752.pdfhttps://www.eevblog.com/forum/beginners/lm324-power-supply-with-variable-voltage-and-current/msg3582664/#msg3582664"
},
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 10, 2021, 03:24:52 pm",
"content": "I think a linear design will be best, yes, but that part is before the displayed circuit. Great trafo you have chosen there, it looks like high quality, if I understand it correctly. :-)"
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 10, 2021, 04:29:40 pm",
"content": "You may want to see the datasheet for the opa549. There is a schematic for a 10a integrated psu.https://www.electronics-lab.com/project/1-2v-25v-10a-adjustable-power-supply-using-power-op-amp/"
},
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 10, 2021, 06:41:09 pm",
"content": "I am happy for your comments and I have done my best to understand it all. My problem is that I do not have enough knowledge to determine the best circuit to reach my goal. The problem about temperature change could properly be solved by adding an oven and maybe keep the temperature at 40 deg C?My goal is to be able to fine adjust Voltage And max Current in as fine steps sanely possible, and have ripples well below that in both voltage and current.I do not care if I have to build a ridicules giant capacitor bank or if it will get large, only goal is precision, not accuracy, the accuracy can be read by a DMM.EDIT: Forgot to write: If I chose a circuit, let's just say the above, to make it easy and do not like the 2V ripple or think 34V 3A is too high, is it not \"just\" to select some components that is better to my goal, i.e. lower ripple but maybe max 11V 2A or whatever the right component can manage?Is there anything stupid, wrong or bad in just using one of your suggestions or the one I randomly found, I mean they sound fantastic, except from voltage or ripple?Can you please forgive me, but reading a circuit and determine its degree of usefulness is far beyond me! :-)"
},
{
"post_id": "",
"author": "xavier60",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 11, 2021, 11:26:37 am",
"content": "There are ways to use 2 pots, one for coarse setting, the other for fine setting. Although good quality multi-turn pots are a good choice, one of thing to be aware of is that the wiper voltage does not change in a continuous way, rather in small steps. The may not be a practical problem.Hybrid pots were developed to correct this."
},
{
"post_id": "",
"author": "FriedMule",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 11, 2021, 12:50:11 pm",
"content": "Sounds interesting, I thought viper pots just had a continues resistive trace inside?To make usage of two pots, would you use one with fewer turns within the total value needed area and one with a small différance from max to min for the fine in series?"
},
{
"post_id": "",
"author": "xavier60",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 11, 2021, 01:07:08 pm",
"content": "I should have mentioned that most multi-turn pots are the helical wire wound type,https://passive-components.eu/precision-potentiometers-type-1/One simple method is to have 2 pots of the same type connected to the same reference voltage with the wipers summed together with resistors where one is say 10 times larger than the other."
},
{
"post_id": "",
"author": "perieanuo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 13, 2021, 07:35:34 am",
"content": "Quote from: FriedMule on July 08, 2021, 06:43:43 pmyepaccumulator>variable regulator>>load. no ripplebattery charged separate from this principle of variable psanyway, you're sure you really need this? all new designs (well, almost all consumer products) are smps-powered, TEST THEM with the smps used in real life after production.otherwise, it's just cheaptalk, chitchat, bla bla bla"
}
] |
2025-10-17T17:25:50.999342
| 18
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10watts-for-all-4-will-it-work/
|
10watts for all 4, will it work - Page 1
|
[
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 05, 2017, 10:41:53 am",
"content": "As making basic EI transformer inverter is super easy i am planning a thingi am adding a triac based switcher to make sure the apparent LED load is within 10W in the inverterso a bulb is made on at a time and fast switch is done so that every bulb look steady glow but inveter can be used is very low wattExperts please suggest will it work ?clarification :::It is not a DIMMERit is NOT a XMAS lightI dont want to use 12V LEDjust DIY $5inverter should be able to do double duty that is 10W inverter drives 20W"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 05, 2017, 10:54:13 am",
"content": "This seems like a bad idea.Why not simply use 12V LEDs?The AC is only converted back to DC inside the LEDs anyway, so it makes sense to use LEDs rated to the correct voltage in the first place."
},
{
"post_id": "",
"author": "Twoflower",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 05, 2017, 11:03:29 am",
"content": "I'm not sure if I understand your plan correct: You try to sequentially power one bulb or probably two at the time, switch to the next and so on. Is my assumption correct?In that case you'll probably run into problems. As the high voltage (110V/230V) LED bulbs contain some circuit that could behave funny if it receive the supply in bursts. It could even shorten the lifetime as the primary capacitor in there will be under additional stress. But again this depends on the circuit in the bulbs. Cheaper ones might survive that better but probably flicker a lot (the ones with no build-in switching circuit).As alternative: Have you thought to skip the inverter and use 12V DC LED bulbs? They might behave better if driven from a PWM source. Or better use LED bulbs that don't need to be dimmed down at all. As side effect: This will have a higher efficiency as you don't to the surplus converting to the high voltage and back down (within the LED bulbs)."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 05, 2017, 11:29:55 am",
"content": "i am making a box inverter and user can use any LED bulb . not a emergency light .. wire length they can use higherthat makes it more suitable also 12v DC bulb is vv rare"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 05, 2017, 11:35:30 am",
"content": "Quote from: Twoflower on November 05, 2017, 11:03:29 am12v bulbs not a option longer cables will be used to put ,say 2 story building .I have used 220V LED bulbs for very longtime on almost square wave inverters bulbs dont care of that .Keeping inverter cost low is main needed , efficiency is not that of concern as similar inverter running with loong 12hr backup( not having Triac switcher)"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "November 05, 2017, 12:35:25 pm",
"content": "You certainly cannot do this. And if you use normal quality LED bulbs which include driver circuit, you won't even decrease power consumption. They will just charge internal capacitor with much higher current in the moment power is applied. Thus reducing it's lifespan. If you need to decrease power consumption, use lower power LED bulbs."
},
{
"post_id": "",
"author": "orolo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 05, 2017, 12:51:29 pm",
"content": "Big Clive wonderfully explains the problem with triac dimming and LED lights in this video."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 05, 2017, 03:59:20 pm",
"content": "Quote from: wraper on November 05, 2017, 12:35:25 pmI agree. Another issue is with using a square or modified sine wave, a capacitive ballast, used in many LEDs, the current will be much higher, than the design value, causing unreliability, possibly smoke and fire."
},
{
"post_id": "",
"author": "jeroen79",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 05, 2017, 04:56:53 pm",
"content": "I don't get what this TRIAC switcher is supposed to do.Is it just a dimmer?If you're starting with 12V DC then converting to AC seems inefficient to me.Look for suitable 12V leds instead."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 05, 2017, 05:52:29 pm",
"content": "Quote from: dave_j_fan on November 05, 2017, 11:35:30 amWhy not? At lower voltages, the current required for a certain amount of power, will need to be higher, but it's only 10W, which is under an Amp at 12V, so the cable doesn't need to be very thick. If the maximum voltage drop is 1V, at 1A, then maximum cable resistance is 1Ohm. 1mm2cable has a resistance of 18.1mOhm/meter, so the cable can be as long as 1/0.0181 = 55.25m, or 27.6m as two wires will be used: one for the positive and anoter negative.https://www.tlc-direct.co.uk/Book/5.3.6.htm"
},
{
"post_id": "",
"author": "Twoflower",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 05, 2017, 06:04:31 pm",
"content": "OK, Hero999 beat me with the post by a few minutes. But I'll post it anywayThe statement \"about the higher drop because using 12V compared to 230V\" doesn't really count for such low loads. Your schematics show a 10W inverter to 4 bulbs. That allows max. 2.5W per bulb. At 12V this is 210mA. Assuming a 50m (actually 2x50 as you have the return wire as well) wire with 1mm^2 has about 1.7Ohm. That means you loss at the wire is less than 74mW.Of course if you want them to 'glow' dimly you can probably drive the LEDS with even lower power and the cable losses will go down a lot. At 1W the losses are already down to 12mW as the current appears squared (P = I^2 · R).If all bulbs are 50m away that sums up to 300mW. Please tell me that your self build inverter has lower losses than 300mW or better than 97% efficiency. Which would be extremely well for a 12V to 230V inverter, you could make money with the design.Edit: Changed calculations from 5 to 4 Bulbs.."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 07, 2017, 10:37:50 am",
"content": "it is not a design challenge ,,,purpose is to deliver low cost inveter for small shop and students12v dc wireloss make unsuitable for little longer lenths of wire where two bulbs will light up ;like a poor mans housethen u may ask why not make 80watt inverter ?this his cost bench mark and needs bulk batteryeven if loss is low 12V leds are vry rare to find , and during gridpower they need 12V SMPS to run adding to inverter cost(inverter auto switch)"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 07, 2017, 02:04:43 pm",
"content": "Quote from: dave_j_fan on November 07, 2017, 10:37:50 amWhat's the maximum wire length?As we already stated, the loss in an inverter will exceed that of a 27.6m, 1mm2cable, at 12V 1A, which is over 91% effient.And as 12V LED bulbs are widely available. I suggest MR16 / GU5.3 lamps. I've recently purchased some for my parent's and sister's house. They've very efficient and run cool, compared to the halogen lamps they're designed to replace.Another option is using a higher DC voltage, such as 24V or more, but I haven't looked into the availability of such LED lamps."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 08, 2017, 06:00:41 am",
"content": "i request all to see the scenario that all bulbs are not available all parts of world. even 12v ones of substandard quality in many partsif the 12v bulb topic is pulled again i will have to walk off .if somone can highlight 230v switching plan that is running on off at very fast rate like 1Khz please sharerunning 12v LED , i dont want to do , the reasons already stated ...... please reply on 230v led only"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2017, 09:16:01 am",
"content": "Why not buy an off the shelf 230V inverter? It will be much cheaper than making one.https://m.ebay.in/itm/3-LED-STRIP-SMD-WATERPROOF-LIGHT-MODULE-5050-WARM-WHITE-DC-12V-FOR-CAR-BIKE-/181612437698?hash=Ng==The LEDs can then be switched using plain old mechanical relays.EDIT:Sorry missed this:QuoteWhy do you want to do that? Do you want to dim the LED? If so, that's not feasible with 230V 50Hz.Why not use a dimmable LED? If so you'll most likely need a pure sine wave inverter.Another option is several lower powered LEDs and a circuit to control how many are switched on."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 08, 2017, 09:29:04 am",
"content": "Hero999,post 0 has all details . Why all are serving 12VLEDfor the the ones who dont read post 0- It is NOT a tip top light-it is NOT dimmer-YES its is SOMTHING else\" it is to switch load very fast so that 10W inverter driver 20watts LED \"i hope no 12v LED suggestions will come"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 08, 2017, 09:33:15 am",
"content": "my inverter is $5 inverter compact , \"DIy\"and 10watts capacitycan it drive 4 of the 5watts LED"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2017, 10:00:18 am",
"content": "Quote from: dave_j_fan on November 08, 2017, 09:29:04 amI posted the wrong link:https://m.ebay.in/itm/150-Watt-Inverter-12V-to-220V-DC-to-AC-Converter-Board-For-Home-Car-Solar-DIY-/282609533548?hash=NA==QuoteDon't be so childish! You don't make the rules here. People are free to suggest what they like. If you don't like it, you're free to ignore it.QuoteBad idea. It wont work. If you can't get a larger inverter, you need lower power LEDs.Quote from: dave_j_fan on November 08, 2017, 09:33:15 amNo, that would overload it, causing it to overheat or some protection circuit to kick in.If you've made the inverter yourself, then why not post the schematic and a picture so we can suggest how to increase the power rating to 20W?"
},
{
"post_id": "",
"author": "Twoflower",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 08, 2017, 07:26:31 pm",
"content": "As many times said: Will it work? --> Probably not.And as this was said we tried to provide you alternative solutions which in general, but not for every case, is superior to your solution. And as we don't know your specific problem we just provided a solution that works in general. If you're not happy with this, you should provide more input to work with. Or take the short answer to your question in the subject line: Probably not.Switching the different lanes at high speed might have a negative impact at a) The losses on the cables and b) emit electro magetic noise.As this was noted here: Your results might be unpredictable. As there are different ways to implement 230V LED bulbs. From 'put as many LEDs in series plus a small resistor' to a full blown SMPS. If the LED bulbs contain a SMPS which might not behave as you hope. The input capacitor will have a high inrush current which might exceed the rated 5W of a LED lamp in operating mode. If you switch off and on the supply the high inrush current will probably repeat. If you use the 'simple' ones they might start to flicker annoyingly.And something you should consider while implementing your inverter: Be aware that some LED bulbs might require a frequency close to 50 or 60Hz. If the bulbs use a capacitor to reduce the line voltage that could fry the bulbs easily."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 08, 2017, 09:59:59 pm",
"content": "I thought why not make the jig ...The bulb fry myth has been busted , i was able to reach a steady glowthe SCR based sequencer works beautifully!All 4 channels are active ... but SCR and bulb is on one channeli will add 3 more SCR and bulbs .testing with 4w PHILIPS bulb on 230V ACI have been using SMPS LED lamps , they seem to respond well to few Khz frequencyall shops and places use squarelike inverters with higher switching freq. the bulbs are doing just fine.(may reduce 1year life, but thats ok of the avg life is say 4 year , reducing to 3year is unnoticable)However , i have delivered all inverters to poor and needy. I will make one 10watterand check if its driving well .But i appreciate the know how shared so far"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 08, 2017, 10:12:38 pm",
"content": "Hero999,buying 150w inverter not an option ..most of these are china clones cant be sure of reliability .the higher watt inverters waste more watts if the load is 10-20w .when Qn is : can i drive 20w load on 10w with sequencerAnswer cannot be make 20w inverteri can make even 100watts one ... but cost and needed battery will make it unusable for the masses .next is regrding posting my inverter scheme.. thats design trademarkits is $5pack with charger and inverter and autoon combo... with battery protection circuits"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 09:43:40 am",
"content": "Quote from: dave_j_fan on November 08, 2017, 09:59:59 pmYes, you need an LED with a switched mode power supply. There will be a limit to the maximum frequency of the supply voltage, because the bridge rectifier on the input stage will gradually become less efficient, as the frequency increases. Running on 200V to 300V DC is another possibility.Quote from: dave_j_fan on November 08, 2017, 10:12:38 pmIf you designed the inverter, then you should know whether it can power a 20W LED or not, so why are you asking that question here? There's no point in keeping the schematic for your inverter secret. There are 100s of schematics for inverters, which can be found on the Internet and many people here are capable of designing one from scratch.Or is the question not about the inverter, but the sequencer? Can you post a schematic for that or is it a secret too?"
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 11:05:04 am",
"content": "I am at a total loss to understand the point of this. Rather than trying to dim a 10W lamp so it only consumes 2.5W, why not start with a 2.5W lamp?How are you intending to switching a TRIAC on/off at a frequency greater than the zero crossings of the 50/60Hz line frequency?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 01:50:58 pm",
"content": "Quote from: mikerj on November 09, 2017, 11:05:04 amPerhaps the inverter generates a higher frequency than the normal mains?"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 03:30:53 pm",
"content": "I would like to disagree to most of the LED bulb horror stories told here and ask everybody to think how it could work, not how it can fail. - Because after all original poster is doing good job - he is trying to make our world better place.My two cents: 10W power is so low that I would not bother about sequential switching, any LED switching at all. I would run all the LED bulbs in parallel - to save on wiring in many installations and create10W PWM-dimmable AC square wave inverter with input current limiter. Current limiter as safeguard against inverter overload and output short. Also it is worth to consider optional frequency control in 50-400Hz(?) range. Maybe it can help with some (too smart or too dumb) LED bulbs or reduce flicker. What's more or less clear here - lot of testing with various LED bulbs needed."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 04:46:59 pm",
"content": "Quote from: ogden on November 09, 2017, 03:30:53 pmReducing the duty cycle using PWM might not work. If the DC:DC converter inside the LED has a smoothing capacitor, it'll take large current spikes on the rising edge of the pulse, with the magnitude and length of the pulse, depending on the impedance and the voltage on the capacitor. If the output of the internal DC:DC converter is constant current, then the power consumption of the LED will not change, until the PWM drops below a point. This might put extra stress on the lamp, leading to premature failure.If the LED's DC:DC converter has no filter capacitor, then it will probably work, but it will flicker at double the mains frequency, unless the inverter works at a high frequency.How do you propose PWMing the AC? It's not possible to do it in increments of less than double the mains frequency with SCRs. Another option is to use two MOSFETs back-to-back and chop the entire AC waveform at a much higher frequency, but that can lead to issues with RF interference and high surge currents, as mentioned above.Phase control is an other option, in which case leading edge should be used with LEDs, rather than trailing edge, but again MOSFETs need to be used, rather than SCRs."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 06:12:31 pm",
"content": "> Reducing the duty cycle using PWM might not work.My guess that it shall work with dimmable LED bulbs.> If the output of the internal DC:DC converter is constant currentI would like to see any <= 10W low-end LED bulb (where OP is aiming at) which have constant current converter inside. Again we CAN find particular LED's which will not work with such approach, BUT again - we shall use common sense here too.> This might put extra stress on the lamp, leading to premature failure.10W total power, 2.5W for each bulb. Again I would like to see - does LED bulbs really fail. After all hard edges can be easily filtered on the inverter output at let's say 1KHz cutoff freq or so.> but it will flicker at double the mains frequency, unless the inverter works at a high frequency.Didn't I say about 50..400 Hz frequency control which could reduce flicker?> How do you propose PWMing the AC? It's not possible to do it in increments of less than double the mains frequency with SCRs.I did say \"I would not bother about sequential switching, any LED switching at all\". My proposal is to PWM-controlinverter.> Another option is to use two MOSFETs back-to-back and chop the entire AC waveform at a much higher frequencyToo complex. Better chop inverter at higher frequency - as I proposed initially.> Phase control is an other option, in which case leading edge should be used with LEDs, rather than trailing edgeSquare wave inverter cannot have any leading or trailing edge phase control because it'ssquare wave. Just looked at available PW controllers. UCC28089 looks like good choice. Additional op-amp and potentiometer needed to augment current sense for PWM-control."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 06:31:57 pm",
"content": "Quote from: ogden on November 09, 2017, 06:12:31 pmObviously alternative option is digitally controlled inverter. Attiny24 is good enough for the job, especially considering it's 20x gain amplifier for ADC which is perfect match for current sense measurement."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 06:52:17 pm",
"content": "Quote from: ogden on November 09, 2017, 06:12:31 pmThat depends on the bulb. Some dimmable LED bulbs look at the incoming waveform and adjust the LED current according.QuotePlenty, just look up LED driver ICs, using a search engine. Here's one example. Many more exist.http://www.mouser.com/ds/2/302/SSL21082AT-843512.pdfQuotePossibly. It would certainly exceed the ripple rating of the input capacitor. Another issue is, if the LED bulbs are in standard fittings, people might replace them with other LEDs which aren't compatible. Look up capacative dropper LED, which certainly will fry if operated from too higher frequency.QuoteGood idea.QuoteThe trouble is, he's already has the inverter and doesn't seem to be willing to redesign it or accept any help with the circuit, as he won't post it because it's proprietary information.QuoteThe only option if changing the inverter is not an option.QuoteActually, if could work, irrespective of the waveform, just delay the turn on, afterQuoteGood, if you're redesing the inverter."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 07:54:34 pm",
"content": ">Plenty, just look up LED driver ICs, using a search engine. Here's one example. Many more exist.>http://www.mouser.com/ds/2/302/SSL21082AT-843512.pdfExistence of drivers does not prove that they are used in low end LED bulbs. You can more or less count on that. BTW you are showing one which for sure will work with \"PWM dimmable square wave inverter\">Possibly. It would certainly exceed the ripple rating of the input capacitor.Ripple rating of the input capacitor?BS. This lesson comes from bigclive LED academy?Crude LED bulbs have that poor series resistor for exactly that reason. - To reduce EMI and obviously ripple current spike when minimum forward voltage of LED string is reached (check IV curve of the led). Most \"dumb\" LED bulbs conduct quite late in the AC cycle. Also we shall take in account that peak voltage of square wave inverter will be just 0.7x of AC mains peak for same RMS voltage output, so current spike difference could be minimal. In short - don't bother about wearing out capacitor or series resistor.>Look up capacative dropper LED, which certainly will fry if operated from too higher frequency.I would not be so certain. 400Hz is not that high frequency after all. Also remember about power budget we are talking here about. Most likely everything will be underpowered and very far from frying.>The only option if changing the inverter is not an option.Then somebody else will save the world"
},
{
"post_id": "",
"author": "orolo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 08:23:57 pm",
"content": "Quote from: ogden on November 09, 2017, 07:54:34 pmNot high frequency at all. Take this cheap \"3W\" dropper bulb from Big Clive's Academy:At 50Hz, the impedance of the 820nF is 3882 Ohms, so the RMS current is 52.5mA, and the 30V LED string dissipates a puny 1.6W, certainly underpowered for an alleged 3W bulb. Now crank the frequency up to 400Hz. The impedance is 485 Ohms, the current 359mA, and the power 10.68Watts. Ax106.6x increase in power, and 3.3x more power than the rating. I'm sure Big Clive would approve."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 08:48:20 pm",
"content": "Quote from: orolo on November 09, 2017, 08:23:57 pmAs you did your homework, then I have no other option than to agree. - In case we talk about 100% duty cycle. But as I suggested not only PWM control but also input current (effectively output power) limiter, then RMS figures will be ok. Thou it is not good to 10x exceed current and I shhall agree that 400Hz is too much. Specs shall be revised"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 09, 2017, 09:01:06 pm",
"content": "Quote from: Hero999 on November 09, 2017, 01:50:58 pmyes it does,inverter is at leat 10x more ....hero999 inverter scheme is fined tuned one . but the switcher i will draw later"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 09, 2017, 09:14:27 pm",
"content": "Quote from: ogden on November 09, 2017, 03:30:53 pmworld better place.--yes.... we will save on led lights power usage ,atleast cut bills to 1/3poor gets backup power,solar lamps need smaller battery ..so onbut pwm dimming is of no use as hero999 outlinedthe SCR gives flicker to 5watt LEDS , but 4watts work flawlessly. I will try with triacREading thishttps://www.digikey.in/en/articles/techzone/2012/oct/avoiding-flicker-in-led-lighting-applications"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 09, 2017, 10:06:22 pm",
"content": "Quote from: ogden on November 09, 2017, 07:54:34 pmIt's not that simple as PWMing the power. Read the datasheet, especially the part about toncontrol.Quote from: ogden on November 09, 2017, 08:48:20 pmYes that's pretty much what I was getting at.No one here is being negative for no reason. There are reasons why people here have recommended things such as a higher power inverter or 12VDC LEDs, but the original poster is either, unable or unwilling to implement them."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 10, 2017, 05:56:35 am",
"content": "no worries with lowering of impedance here , smps bulbs only.people will be instructed to buy standard LEDs all are SMPS... we specify make and wattthere are Khz frequency inverters in market , running LEDs for long periods.power-slicing : i call it .....its the TDM ( time division multiplexing) of ACPersonally i try to avoid complexity in implementation. Bringing special chips for the job are last options.I will use just 4017like sequencing ICs so that parts are available everywhere .Quotei already have non-isolated driver based bulbs with similar chips . they too will be used in tests .i may be noob here but Qn ariseswhere PWM dimming has come here ? we dont want to dim the lamps and reduce power .we want same light for a much lesser power"
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 09:43:20 am",
"content": "Quote from: ogden on November 09, 2017, 07:54:34 pmYou seem to be somewhat confused. It's true the very cheap, low power lights use capacitive droppers, but when you are talking about a 10Watt LED lamp for a conventional lamp fitting then it is almost certain to be using a constant current switching regulator. I took apart some cheap GU4 bulbs recently and even those used a switching regulator.If it has a bridge rectifier and smoothing cap, then any attempts to dim the LED through e.g. phase control or PWM will greatly increase the peak current through the rectifier and the ripple current through the smoothing cap.The OP is not saving the world, he's trying to create a very complex solution to what appears to be a simple problem, and refuses to consider any other way of solving it."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 10:06:04 am",
"content": "Quote from: mikerj on November 10, 2017, 09:43:20 amI agree. Unless a special type of LED controller is used this won't work.Quote from: dave_j_fan on November 10, 2017, 05:56:35 amIf you want to control the sequence of some lamps, then why not use a microcontroller? It will be more flexible than one of those old ICs and doesn't require as many components.QuoteIf it was possible to produce the same light for less power, then don't you think the LED lamp manufacturers would have already done that?Your scheme will not give you the same light for less power. It will use more power to give you the same light and poorer reliability or slightly less power for much less light, again with poorer reliability.Simply switching the LEDs on and off at a high frequency will not lead to any increases in efficiency, even if such a scheme were compatible with the integrated driver electronics. The human eye perceives the average brightness of a light flashing at a high frequency. If you flash a 10W bulb at 1kHz, equal time on and off, it will appear to give off the same amount of light as a 5W bulb.In practise, if you tried to do that with a ready made LED, with a constant current DC:DC converter, the results will be unpredictable. It might: produce the same brightness but draw double the current, causing potential reliability issues, flicker horribly or just be dimmer.Another factor is the non-linear response of the human eye. A 5W lamp may not appear to be half as bright as a 10W lamp, so even if you think you're successful by using half the power, for a slight drop in apparent brightness, you'll find the 5W lamp would have been a better option."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 10:28:44 am",
"content": "Quote from: dave_j_fan on November 10, 2017, 05:56:35 amIf you have found a magical (and it would require magic) scheme to quarter the power consumption of an existing LED lamp for the same light output by manipulating the line voltage then you need to get a patent sorted out ASAP."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 11:33:00 am",
"content": "Quote from: dave_j_fan on November 09, 2017, 09:14:27 pmThe prices of solar panels and batteries are falling and are becoming a more attractive option, especially in areas with high electricity prices. There are other options, such as wind and energy from waste (look up biogas and gasification) which can be used to provide power on a small scale.QuoteThat article discusses LED DIMMING, using phase control. It will not help you achieve higher efficiency."
},
{
"post_id": "",
"author": "Damianos",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 12:51:29 pm",
"content": "Quote from: dave_j_fan on November 05, 2017, 10:41:53 amOf course it will do!You can also expand it. At each output from the switcher, connect another switcher ... and, continuing this, you can have unlimited power/energy to lighten up the entire planet.But not only this. If you start combining the outputs after a few billions of switchers, there will be plenty of power for trains, factories, homes, etc.Still, if from some of the outputs re-feed the input, you can save and battery ... After start-up, you can remove it and your invaluable inverter!Watch out! There will be many who will try to steal your designs ... ...To be serious!Are you insisting that a fast switching, with TRIACs or anything else, can cheat on the rules of physics?"
},
{
"post_id": "",
"author": "Connoiseur",
"author_rank": "Regular Contributor",
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"timestamp": "November 10, 2017, 01:47:18 pm",
"content": "Quote from: Hero999 on November 10, 2017, 10:06:04 amI would be glad to know the lm/W output of such a contraption.Boy! the OP should watch more free energy videos on YouTube."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 09:10:04 pm",
"content": "Quote from: mikerj on November 10, 2017, 09:43:20 amBefore you label someone as confused, you shall comprehend what he is talking about. I shall remind that main topic was not \"capacitive droppers\" as such but exceeding ripple rating of input capacitor and it's consequent failure. Even in case of constant current switching regulators square wave input shall not accelerate failure rate unless design is flawed. Knowing target customer and assuming that he will buy 10W LED bulb with current switching regulator inside is kinda... uneducated thinking. If total power provided for 4 bulbs is 10 watts - then what's the point of paying for 4x10W bulbs?Quote from: mikerj on November 10, 2017, 09:43:20 amIf LED is designed as dimmable, it will work. Try to think of solution too, not only just dig up flaws. Actually latter is much easier.Quote from: mikerj on November 10, 2017, 09:43:20 amOh, Mr.Obvious. Do you know concept ofsarcasm?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 09:50:12 pm",
"content": "Quote from: ogden on November 10, 2017, 09:10:04 pmThe power dissipation in the capacitor/inrush limiting resistor will be higher with a 50% duty cycle square wave, than a sine wave. If the inrush limiter has a negative temperature coeffient, then it might be fine, since the increased current might reduce the resistance enough to avoid the power dissipation getting too high, otherwise it could fry.See the attached simulation. With a 500Hz 50% duty, 325V (the peak voltage for 230VAC), the power dissipation in R1 (the surge limiting resistor) will be 500mW. When V1 is changed to a 500Hz square wave, the power in R! increases to over 2.5W. I'll attach some screenshots later.QuoteIt might work or it might not. It depends on how the dimming is implemented. With the IC data sheet I linked to earlier, it certainly wouldn't work.QuoteUnfortunately sarcasm often gets lost in the depths of the Internet."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 10, 2017, 10:55:51 pm",
"content": "Quote from: Hero999 on November 10, 2017, 09:50:12 pmDid not able to interpret .asc file provided, sorrry.Your beginners error is that square wave inverter will not output \"325V (the peak voltage for 230VAC)\" but 230VAC RMS voltage which is essentially 230V peak.So, RMS power dissipation in R! in case of square wave will be identical. Where's the catch? Actually I was beginner here, apologies. 230V peak of square wave inverter at 100% duty cycle will give same power as RMS 230VAC only for resistive loads. LED with rectifier inside needs 325V peak disregarding it is sine or square wave.Quote from: Hero999 on November 10, 2017, 09:50:12 pmDetailed explanation please ."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2017, 12:06:14 am",
"content": "Quote from: ogden on November 10, 2017, 10:55:51 pmNo.For a start, in order to work properly, the inverter would have to output a voltage of 325V, since that what will be on the capacitor, after the rectification of the 230VRMS mains, which has a peak voltage of 325V. Don't believe me? Connect a 12VAC transformer to a bridge rectifier and capacitor. You'll find that the voltage on the DC side, is equal to about 1.414 times the AC side, minus the diode losses. Even if the voltage were reduced to 230V, the power dissipation would still be higher, than for a sine wave.QuoteDid you refer to the data sheet, paying attention to the part about toncontrol, pin 8, the TONMOD pin? The dimming function is dependant on the timing of the sine wave on the input to the rectifier.http://www.mouser.com/ds/2/302/SSL21082AT-843512.pdf"
},
{
"post_id": "",
"author": "kalel",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 11, 2017, 12:07:18 am",
"content": "As (little) as I know, multiplexing does decrease the brightness we perceive, since each LED is only on for some time. Even a single LED switching \"on off\" faster than we can see will produce less light than a constantly on LED, because it will be some \"on and off\" output average that we see rather than just \"on\" output.As far as capacitive droppers, I'malmostcertain I have seen capacitive droppers in cheap claimed 9/10W LEDs. I haven't measured the wattage to see what it outputs really, but they are quite bright, and don't last too long (up to a few years). Sometimes the LEDs get burned (lack of proper heat-sinking?) - they first get darker spots, still work for a while - and finally fail, sometimes the electrolytic capacitor fails (it does get moderately heated, I don't know how a better capacitive dropper design could mitigate this issue)."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
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"timestamp": "November 11, 2017, 02:40:40 am",
"content": "Why you are using 50Hz for sine and 500Hz for inverter? Anyway - you just completely ignore all the other \"specs\" of the project including 10W power limiting of inverter output, it's duty cycle which for sure will not be 100%, you put hi-voltage 47uF capacitor into low cost LED (!).Also this:>Did you refer to the data sheet, paying attention to the part about ton control, pin 8, the TONMOD pin?is not detailed explanation but more like trolling."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2017, 10:12:00 am",
"content": "QuoteThe point of getting reduced light like 5Wled bulb from 10w with 1khz frequency is not valid , in khz range the LED gives almost same brightness.I have tested it, with few brands like hevells, philips ..For the point \"flicker\" \"dimmer\" is also not fully true .my Jig already achieved same light for 4W LED . I have tested with SCR as active element .yes the 5W led gived a breathing like fliker mey be because SCR have reduced the voltage .I have reduced the off period to 1sec and the SCR switch is giving flicker , means..TRIAC tests will ... hopelfully make the jig workThe discussion is very informative. I am going baby steps way to make the jig flicker free .Jig will feed from a small diy inverter .... DC current i will measure and find the truth .remember JOULE ringers running 10LED bulbs ...so possibility is always there"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2017, 10:17:41 am",
"content": "will see ...for your information i have a DC led tube , i added PWM and reached 12hours light ... originally it was giving 3-4hourdont bring physics if you dont know pulsed and switched led lighting saves lot energy .however i have less test knowledge on AC so asked experts"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2017, 10:21:25 am",
"content": "Quote from: dave_j_fan on November 11, 2017, 10:20:02 amwill see ...for your information i have a DC led tube , i added PWM and reached 12hours light ... originally it was giving 3-4hourdont bring physics if you dont know pulsed and switched led lighting saves lot energy .however i have less test knowledge on AC so asked experts"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2017, 12:01:49 pm",
"content": "Quote from: dave_j_fan on November 11, 2017, 10:21:25 amYou assume you are getting same light output while LED is PWM-dimmed, but you are not. Do you have lux meter to measure light output? If not, then take two identical LED bulbs, run one w/o PWM and another with PWM at the same time so you can compare brightness. It will differ for sure."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2017, 01:28:38 pm",
"content": "Quote from: ogden on November 11, 2017, 12:01:49 pmit may be slight reduced but probably reducing heat loss it maintains good amount of intensity.The tube is very good usable light for small kitchen.I have even distributed Khz range power boosted lights . 12v to 230v . pulsed mode maintains nearly same intensity in bulbs .My observation.I junked 3 circuits for lower light , finally found super bright one"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2017, 04:17:33 pm",
"content": "Quote from: ogden on November 11, 2017, 02:40:40 amBecause an off the shelf LED lamp will be designed for 50Hz operation, not 500Hz. Think about it.QuoteIt's typical for the input stage of a mains powered LED. Do some research, before making stupid comments.QuoteDon't accuse others of trolling, just because you don't understand something.Quote from: dave_j_fan on November 11, 2017, 01:28:38 pmHave you measured the power consumption?Have you done any objective measurements of the brightness, using a meter, rather than ones eyes?Bear in mind the eyes can easily be fooled. A 10W bulb won't look twice as bright as a 5W bulb."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2017, 06:35:32 pm",
"content": ">Because an off the shelf LED lamp will be designed for 50Hz operation, not 500Hz. Think about it.Oh, thank you for schooling. Actually I wanted to know where 500Hz for inverter came from>It's typical for the input stage of a mains powered LED. Do some research, before making stupid comments.47uF typical for low cost LED bulbs? - Show your data.>>>Did you refer to the data sheet, paying attention to the part about ton control, pin 8, the TONMOD pin?>>is not detailed explanation but more like trolling.>Don't accuse others of trolling, just because you don't understand something.Thenexplainin details so we can understand why particular chip will work from dimmed 50Hz sine wave but will not work from 50Hz PWM square wave. I want to know which part of mentioned datasheet explains that. So I ask you again: please givedetailed explanation."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2017, 07:51:59 pm",
"content": "Quote from: ogden on November 11, 2017, 06:35:32 pmPlease read the thread from the beginning. The original poster intends to drive a bulb rated for 50Hz, using an inverter with a much higher frequency square wave. It should work with a continuous duty cycle +/-230V to 325V square wave, as long as the frequency isn't too high for the diodes in the bridge rectifier to switch, but not for a square wave with 50% duty or modified sine wave.The value of the filter capacitor is not important. It was an example of a typical input stage of an LED lamp. Bridge rectifier -> surge limiting resistor -> capacitor. The idea was to demonstrate, that powering it from a 50% duty cycle square wave can cause excessive power dissipation in one of the components. Another issue is, this may work on the bench but prove unreliable in the field. Often overstressed components don't fail immediately but blow up much later.The dimming function of that is dependant on the mains frequency being near 50Hz, 60Hz or whatever the circuit is designed for and changing the frequency will mess it up. Don't forget that he doesn't have any control of the circuit being used to power the LED, only the voltage input to it. Another issue is he doesn't want to dim the LED. He wants to power it at full brightness, whilst reducing the power consumption: an impossible feat!"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2017, 07:53:26 pm",
"content": "Quote from: Hero999 on November 11, 2017, 04:17:33 pmi respect that new information ... i stated by observation of the light in the room not just bulb on table.Today 2 channel test success with 5Watt and 4watt .the 5watt leds had flicker,todays test used TRIAC. It is maintaining good brightness.may be 3-4channel mux will be ok.all inverters i have given to poori will get parts and test 1bulb inverter to drive 2 bulbs.technically it must work because 230V test is promishing .Just frequency is in khz range ."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2017, 11:48:50 pm",
"content": ">Please read the thread from the beginning. The original poster intends to drive a bulb rated for 50Hz, using an inverter with a much higher frequency square wave.I can say the same to you because:1) I am not original poster2) I suggested inverter with tunable frequency 50-400Hz range and tunable duty cycle, with input current limiter which will essentially limit output power to nominal.3) you jumped on me when I said:\"I shall remind that main topic was not \"capacitive droppers\" as such but exceeding ripple rating of input capacitor and it's consequent failure. Even in case of constant current switching regulators square wave input shall not accelerate failure rate unless design is flawed.\"4) Then you came up with LTspice design where you conveniently (for you) ignore fact that inverter frequency, output voltage and duty cycle can be adjusted to meet design requirements one of which would be \"do not accelerate LED bulb failure\".I suggest you to run your inverter LTspice not with 50% duty cycle, but 100% which essentially is DC coming out of bridge rectifier, tune peak voltage so LEDs dissipate identical power compared to AC sinewave design and only then check power dissipation in the inrush limiter resistor. Maybe then you will understand what I did mean by saying \"Even in case of constant current switching regulators square wave input shall not accelerate failure rate unless design is flawed.\".>The dimming function of that is dependant on the mains frequency being near 50Hz, 60Hz or whatever the circuit is designed for and changing the frequency will mess it up.well then dont change it. remember? - I did leave 50Hz option in my offer."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 12:17:25 am",
"content": "Quote from: ogden on November 11, 2017, 11:48:50 pmNo but you can read what they've written.QuoteThe original poster mentioned using a higher frequency, than 50Hz mains first.https://www.eevblog.com/forum/beginners/10watts-for-all-4-will-it-work/msg1344171/#msg1344171QuoteNo one jumped on anyone. The point was that there are a variety of different designs of LED lamps. It's impossible to know what they'll do when you change the input frequency/duty cycle, without lots of prior testing or reverse engineering. What's worse is that with a standard fitting, someone could easilly change the lamp to an incompatible one, which could blow up.QuoteNo, I modelled the typical input stage of an LED lamp and explained why it can overheat if you try to dim it by PWMing the input voltage.QuoteI know and even said previously that it will work off DC, but what's the point when with 100% duty cycle, there will be no reduction in power consumption or brightness?https://www.eevblog.com/forum/beginners/10watts-for-all-4-will-it-work/msg1345097/#msg1345097Varying the supply voltage (whether AC or DC) will not change the brightness or power consumption of some LED lamps, because they contain a constant current driver, which tries to keep the current through the LED chips the same, despite changes in supply voltage.QuoteGood and better made it a pure sine wave, which is a more complicated inverter design, just to be sure it works.Quote from: dave_j_fan on November 11, 2017, 07:53:26 pmPlease post some schematics of what you've already done.Have you tried it with a variety of different LED lamps? Is there a risk the user might do something silly like replace the LED lamp with an incandescent or compact fluorescent?"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 01:02:38 am",
"content": "Quote from: Hero999 on November 12, 2017, 12:17:25 amI did. On the other hand, you did not read what I wrote.QuoteHow many times I shall remind you that you opposed me, not original poster?QuoteIf everything is designed correctly - nothing will blow up.QuoteWell... as I indicated - you did it wrong.QuoteDC is starting, \"calibration point\" - for you to correct your LTspice LED bulb simulation. After you tune design to work correctly off DC, you will see that it will not tend to blow up when PWM'ed to lower than 100% duty. Proper dimmable square wave inverter will not blow up LED bulbs faster than triac dimmers. This is what I am telling you all the timeQuoteYou are kidding me or what? Please re-read it carefully: \"tune peak voltage so LEDs dissipate identical power compared to AC sinewave design and only then check power dissipation in the inrush limiter resistor\".QuoteActually I believe that original poster have better option: instead of designing, manufacturing and selling inverter & fancy 4-led sequenced to end-customers, better just sell them 12V LED bulbs"
},
{
"post_id": "",
"author": "Damianos",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 01:36:38 am",
"content": "Quote from: dave_j_fan on November 11, 2017, 10:21:25 am[... even if you have mixed up the quotes and you are answering to yourself!]Oh! I know a lot of things, but I keep some secrets!The nature was born before the LEDs and switchers, so does not know about them!Also, I know that half of the power on LED lights hidden somewhere and waiting for an enlightened to reveal it!I work on a similar project but much more advanced. As you know LEDs are also light detectors, they generate voltage and current when light hits them. Using a suitable mirror and switching them fast, they produce energy from their own light! The only unsolved problem is synchronization of switching with the time that the light beam needs to travel up to the mirror and return back. As I don't know enough aboutpulseand switching circuits, I use apushingswitch manually. I need some help to slow the switch contacts, as they are faster than light ... ..."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 12, 2017, 03:11:55 am",
"content": "apart from law of physics and ranting why it wont work.Why not some members try it..$5 in parts wont hurti am not saying physics is bypassed but telling non conventional ways to light leds.The work by lidmotor in energetic forumsshow that with less watt also you can get same brightness.Experiment ,change,try.mcu> 4017>triaccircuit is as simple as that- -----for people fighting on \"what will work\" why not come with own test jig post real reading of ac powerwhile running battery drain tests in my inverters i checked some random things and found adding 100uH inductor in series on ac side , or 1uf 400v cap in seriesthe battery drain is reduced.Be practical you will discover some secrets--is the objective is to save power ?Not exactly but if we can good . First target is to reduce loading of the inverter.25W inverter if it can run 50w leds ....we save lot on per inverter cost .common people benifitted with econmical invertersgetfull house lights for too lowspending .They need small battery that further reduces cost ."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 09:11:09 am",
"content": "Quote from: dave_j_fan on November 12, 2017, 03:11:55 amDid you wear tinfoil hat while discovered those secrets? BTW you can reduce battery drain even further by switching your inverters off. Such experiments that just measure consumed power without measuring resulting light output are useless."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 01:59:43 pm",
"content": "Quote from: ogden on November 12, 2017, 01:02:38 amYes, it did. It was wrong and someone else, as well as myself, corrected it.QuoteWe did inform the original poster that this could be an issue and don't take things so personally: if you post something which is incorrect, people will correct you.QuoteAnd operating an unknown LED lamp from a PWM square wave is bad design, so there's a risk it will blow up. Even if you manage to optimise the design for a particular brand/design of LED lamp, it's in a standard fitting, so there's a risk someone might change the bulb for an incompatible one, which will blow up.QuoteHow is it wrong? If I made any errors, please point them out and correct them. Bear in mind there are lots of different LED lamp designs. . .Here's another mains powered LED lamp design. This time I've posted the full schematic. It's worse because it has no inrush limiter. C1 and D1 to D4 may be able to handle the occasional inrush, but PWM this and it will be destroyed.https://www.alibaba.com/product-detail/Proxy-AC-LED-Driver-IC-FT838RNA_1624190417.htmlQuoteNo, there is a risk it will blow up. Suppose the circuit can safely run off 230VDC safely, without any problems, it does not mean that it can run off 230V with 50% PWM safely. Every time the power is applied, a large current flows through the surge suppression resistor to charge the capacitor. The bulb will only be designed to be turned on occasionally, not turned on and off, from an abrupt square wave hundreds of times per second.PWM is only good for controlling the power delivered to linear loads such as resistors and motors. It is no good for non-linear loads, such as switched mode power supplies, which are often found in modern LED lamps. Just because you can PWM an LED + series resistor, it doesn't mean you can PWM a mains LED lamp.QuoteAnd how are you going to check the power dissipation in the inrush limiter, inside the LED bulb, without dismantling it? Bear in mind that it's difficult/impossible to open some LED bulbs, without damaging them in the process and as mentioned above, the bulb is in a standard fitting, so the user might replace it with another one which won't work the same way.QuoteI agree. He's been told that plenty of times.Quote from: dave_j_fan on November 12, 2017, 03:11:55 amYou'll get a more positive response if you actually posted schematics showing what you're doing.If you really are intent on saving the planet, rather than making money, then you shouldn't keep anything secret. Spread the information, so others can join your quest to save the planet."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 12, 2017, 05:22:48 pm",
"content": "Quoteno one should come here after few shots ofhttps://i.pinimg.com/736x/8d/e1/cf/8de1cf0f2067f77759f1023c75d48e38--whisky-jack-jack-daniels-single-barrel.jpgHero999,Here I am donating the billion dollars ..!Code:/** Simple LED sequencer using a 4017 counter.* The 4017 is used to save pins on the arduino.** Developed by daveJ Fan**//* PIN used to send clock pulses to the counter. */int clockPin = 2;void setup() {pinMode(clockPin,OUTPUT);}/** Sends a clock pulse to the counter making it advance.*/void clock() {digitalWrite(clockPin,HIGH);delay(1);digitalWrite(clockPin,LOW);}void loop() {/* Send a clock pulse to the counter. It makes the counter advancecausing the current LED to be turned off, and the next one to beturned ON */clock();/* Wait for 30 ms. */delay(30);}well code is copied and at the output LEDS there is a opto-TRIACIts too easy .Even simple 555 will work with this ..Quoteyou have motivated meto do the right thing"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 05:28:47 pm",
"content": "I take it the IC on the right hand side is the CD4017?Why not just use the Arduinio? There's no need for the CD4017."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 12, 2017, 05:38:00 pm",
"content": "arduino will be retiredto cut cost , adding bjt /555 lateryes , IC on right is 4017"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 12, 2017, 05:47:32 pm",
"content": "for people with interest thejohnny aum night light. is an example of getting very nice light with 51Milliwatts power, driven LED is 2.8watts ! Point is there are many possibilitieshttp://www.energeticforum.com/296163-post38.html?s=03f790b602cb7fbdb175e0416c3a83d4"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 06:02:30 pm",
"content": "Quote from: Hero999 on November 12, 2017, 01:59:43 pmKeywords here are dimmable LED bulb and LED bulb that tolerates triac dimmers. Please read below.QuoteError 1) You compared dissipation of each inrush limiter resistor without showing dissipation in each \"LED equivalent\" made out of current sink. For fair comparison they must be equal. So basically useless comparison.Error 2) You compared 100% duty cycle (undimmed) AC mains to 50% duty cycle square wave. Again useless comparison.QuoteRight. Those which will fail from leading-edge mode triac dimmer input most likely will fail from square wave too. - As I said already multiple times that \"Proper dimmable square wave inverter will not blow up LED bulbs faster than triac dimmers.\"QuoteWell, thank you. For balance I will share one much more interesting - from engineering point of view.https://www.fairchildsemi.com/product-technology/direct-ac-drive/QuoteWhen dimmed from leading edge mode triac, sharp pulse up-to full Peak-Peak voltage of AC mainseach half-cyclewill be applied to it while at particular dimmer setting:Further reading:http://www.ledsmagazine.com/articles/print/volume-8/issue-6/features/led-lighting-must-work-with-legacy-dimming-technologies-magazine.htmlQuoteThat one particular LED bulb controller you gave datasheet for, does support triac dimmers, both leading and traling edge. Hows that?QuoteCrlt+click on waveformYes, I did talk about your LTspice simulation, not LED physical bulb."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 07:01:11 pm",
"content": "Quote from: ogden on November 12, 2017, 06:02:30 pmThat's all fine, until the user replaces it with a non-dimmable lamp.QuoteWhat do you mean by LED equivalent? The power rating of one of the components is exceeding its rating by a factor of 5, when run on a 50% duty square wave vs the sine wave it was designed for!QuoteI agree so perhaps my simulation, wasn't so incorrect after all. It demonstrates why a non-dimmable LED will fail, when operated from PWM.QuoteIt supports TRIAC dimmers, not PWM! They are not the same thing!Ok it might not blow up but flicker, when run off the wrong frequency square wave, rather than a sine wave. Still not good.Why not simply use a 50 or 60Hz sine wave inverter and a proper dimmer circuit for a dimmable LED lamp, rather than risking failure with a square wave, at the wrong frequency? That's a much better solution. Use components, as they're designed to be used, within their specifications. Attempting otherwise, only leads to trouble, further down the road.By the way, thank you for posting the second link. It might help to explain to the original poster, why his LEDs aren't getting any dimmer.QuoteWhat do you mean by?QuoteI re-read it several times and it makes no sense!The LTSpice simulation was an approximation of an LED driver circuit, run off a bridge rectifier and capacitor. The LED is modelled as a current source, but in reality, it will be a constant power circuit, i.e. a switched mode power supply. The input current will increase, as the voltage on the capacitor falls (down to a certain point of course) which should theoretically, increase the power dissipation on the surge limiting resistor, as the supply voltage is reduced. The end result will be the same: PWMing it will cause no dimming and premature failure.Quote from: dave_j_fan on November 12, 2017, 05:38:00 pmAnother option is a ring oscillator. I designed a PCB for one awhile ago, as a learning exercise.https://www.eevblog.com/forum/beginners/my-latest-eagle-pcb/msg10497/#msg10497By the way, no that would not make mains LEDs use less energy, but keep the brightness the same. They will either get dimmer, or the controller IC inside the mains LED lamp, will increase the current draw, to keep the brightness constant. If the latter happens, there's more risk of premature failure of the LEDs or inverter, used to drive them. You need to invest in a power meter. One which will work with a square wave and at different frequencies than the standard 50 or 60Hz mains. Measuring the voltage and current simultaneously and applying Ohm's law doesn't give you the true power, although it will give you a good idea of whether the inverter's output current rating is not being exceeded.I have a non-dimmable mains LED lamp. I've tried using it with a phase controlled dimmer. The brightness stays constant, until the dimmer setting is reduced past a certain point, then it starts flickering and stops working. I have not measured the power consumption with the dimmer, but I'm pretty sure that it's not using less power, with the dimmer, than without it. I didn't test it for long, because it's likely it would have damaged the dimmer.Quote from: dave_j_fan on November 12, 2017, 05:47:32 pmThat looks like a Joule thief. A very old circuit. It's totally different to what you're doing, because the LED's driver has been removed, so it's powering a bare LED. That circuit doesn't magic 2.759W from nowhere! The 2.8W bulb is clearly running at a fraction of its rating brightness, because the current through it is much lower than the rating. It's true that driving an LED, at a lower current, than its maximum rating increases the efficiency, up to a certain point, but it works out very expensive to buy LEDs rated for much more power, than they'll be driven with, so LED manufacturers won't do it. How many people would by a 1W LED which costs nearly as much as a 10W LED?"
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 12, 2017, 07:40:08 pm",
"content": "Quotesuperb option , how to make it a variable freq one , adding 10K Vr in feedback ?QuoteI know abt JT and made 5 types some time back , but the circuit is not a exact JT as there is no twocoils with 3 pint connection than itz a series connected coil type .What is interesting is 51milliwatts !! for 75% 'usable light' ,this gives me idea of pushing the 9W for all room light with this type circuit. This type of boosters will run well in shops and 1student room alikes ."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 08:14:56 pm",
"content": "Quote from: dave_j_fan on November 12, 2017, 07:40:08 pmThe values of all of the 10k resistors need to be varied, which is probably not practical.QuoteThere are several different variants of the classic Joule thief circuit. In this case, because both of the coils are connected in series and are magnetically coupled, they behave like one coil.QuoteDon't let the picture fool you. It isn't using 51mW to produce 75% of the light of a 2.8W lamp. It's an illusion."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 09:39:16 pm",
"content": "Quote from: Hero999 on November 12, 2017, 07:01:11 pmChecked your LTspice design and agree - \"dimmer incompatible\" LED bulb which is based on constant current IC, most likely will fail due to overheat.QuoteThey are indeed. PWM synced to AC mains phase and frequency can do same thing as triac dimmers do. PWM does not relate only to DC chopping. You can do PWM on any waveform you want.If you feed dimmer-compatible LED bulb IC with 50Hz(!) square wave - it will sync to it. When you PWM-chop 50Hz bipolar square wave coming out of push-pull or full-bridge inverter, then dimmer-capable LED bulb IC will happily detect dimming. Am I missing something here?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 10:13:39 pm",
"content": "Quote from: ogden on November 12, 2017, 09:39:16 pmPWM has a similar effect to phase control but it is not the same thing. PWM isn't normally used in AC circuits, because it's much easier to use phase control and when it is used, it's usually referred to as burst or full-wave duty-cycle control. The PWM is synchronised to a much lower frequency than the mains, causing it to get chopped up into blocks of full cycles, followed by off periods. The ratio of full mains cycles, to off periods is the duty cycle.It looks like this:Obviously this is no good for lighting, because it will flicker, unless the AC frequency is very high, so it's used for heating. The main advantage over phase control is, switching only ever occurs at the zero crossing time, there is no abrupt switch on/off of current, so it's less noisy.If the sine wave is PWMed at a much higher than its fundamental frequency then it will be chopped up into tiny pieces and look like the right of the image below. On the left shows phase control, which many people confuse with PWM.http://www.edgefxkits.com/ac-pwm-control-for-induction-motorI imagine it's very noisy, which is why I've not seen it in real life, only on forums.As far as powering a dimmable LED lamp, which is designed for use on 230V 50Hz AC, from PWM DC is concerned: it may, or may not work. To stand the highest chance of success, use 100Hz or 120Hz, rather than 50Hz, because that's what the LED driver IC will see on the DC side of the rectifier."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 10:32:34 pm",
"content": "Quote from: Hero999 on November 12, 2017, 10:13:39 pmIndeed dimming is rightwordfor AC mains phase control but principles to PWM is the same - as I already explained. So to say \"Dimming is not PWM. Period.\" is not quite correct as well.QuoteIt is. Modern PFC uses hi-freq PWM for AC mains power factor correction. Waveform looks like you are showing \"the real PWM control of AC\".QuoteYou (again) ignored what I say. Reminder in bold:50Hz bipolar square wave coming out of push-pull or full-bridge inverterafter rectification will look like pulsing 100Hz."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 12, 2017, 11:26:25 pm",
"content": "Anyway soon all LED bulbs will have no switching converters or bulk capacitors which are main contributors to price and failures too.From inside they will look like this:Not like this:Such design with PF approaching 0.98 acts like resistive load and will have no problems to work from any waveform you drop at it. Just don't exceed voltage rating"
},
{
"post_id": "",
"author": "kalel",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 01:34:31 am",
"content": "If I have seen it right, it looks like a circuit with an integrated driver (I don't know what else to call it), similar to the video below. Don't those designs experience a lot of flicker as is?There might be new designs that solve the flickering, or perhaps what you showing in the image is a different type of circuit all together."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 07:53:34 am",
"content": "Quote from: kalel on November 13, 2017, 01:34:31 amDifferent indeed.QuoteExactly opposite.They are based on AC-direct regulation IC which progressively switches on each of 4 LED strings until all are illuminated at the mains voltage’s peak. Note that for simplicity circuit below shows just 3 strings. This allows to \"cover\" with illumination nearly all the AC mains cycle. Resulting light is nearly flickerless.Article here:https://www.electronicsweekly.com/news/why-not-direct-ac-drive-your-led-string-2016-04/I already mentioned ON Semi FL77904 which is single chip 4-string IC requiring few small passives, bridge rectifier and that's it. Power factor better than 0.98(!). It is beauty if we can say so about engineering.http://www.onsemi.com/PowerSolutions/product.do?id=FL77904"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 08:50:45 am",
"content": "Quote from: ogden on November 12, 2017, 10:32:34 pmDimming is not the right word for AC mains phase control, since it can be used for other purposes than lighting, such as controlling the speed of motors and the power output of heaters.QuoteNot quite. Power factor controllers, PWM the DC side of the rectifier, not the AC side.QuoteOh I see what you meant now. No I wouldn't recommend doing that. Chopping the output of the inverter, would result in much higher frequency components, which might not play nicely with the LED driver, unless you're talking about something else.It would be better to rectify the output of the inverter, then PWM that at 100Hz."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 11:27:46 am",
"content": "Quote from: Hero999 on November 13, 2017, 08:50:45 amAgain you assume inferior design.All UPSes with \"simulated sine\" output have what we call here \"chopped inverter\". Yet they somehow pass EMC regulations, computers are happy with such waveform, most likely LED bulbs will too. Chopping happens on primary side of the transformer, output have just quite simple (L)C filter.Having proper snubbers on primary and some filtering on secondary winding of the transformer, output looks not that bad at all (from hi-freq ringing point of view):https://www.hardwareinsights.com/database-of-ups-output-waveforms/QuoteSuch waveform will cause much worse inrush current problems than modified sine wave, drooper-capacitor LED bulbs most likely will be very unhappy about such input too. When you feed such modified sine into your \"LTspice LED bulb\", you will see that 10ohm resistor dissipates only ~1W at full power and ~1.1W when 50% dimmed. This BTW is just 2x exceeding \"pure sine rating\""
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 12:28:45 pm",
"content": "Quote from: ogden on November 13, 2017, 11:27:46 amNow you're making an assumption too: that output of the original poster's inverter is a modified sine wave. You've also forgotten that the original poster doesn't want to or cannot change the inverter.Unfortunately we have to make assumptions, in the absence of all the information. The original poster has not posted a schematic or an oscillogram of the output waveform of their inverter, so we don't know the full story.QuoteDC PWM will be no worse or no better than a modified sine wave, for the circuit I simulated in LTSpice. Yes a capacitive dropper won't work from PWM DC because, it will be blocked by the capacitor.QuoteYes, still not good though and could lead to reduced reliability."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 12:39:27 pm",
"content": "Quote from: Hero999 on November 13, 2017, 12:28:45 pmYou'v forgotten that you discussing to me here, not original author. I do not share authors plans, provided mine in return. Obviously when I say something about inverters and so on, I am considering my view, not original posters plans. That's it. Tired of reminding. Bye."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 12:49:26 pm",
"content": "Quote from: ogden on November 13, 2017, 12:39:27 pmAnd you've forgotten that this is not your thread! By barging in to some one else's thread, you've derailed it and created pages of useless information, which is totally irrelevant to the original poster's question, which is not helpful.If you wanted to discuss your inverter/LED lamp design, then you should have created your own thread, rather than derailing someone else's!I apologise to the original poster for playing my part in this. I should have recognised this and stopped responding to you, long ago."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2017, 01:18:05 pm",
"content": "Quote from: ogden on November 12, 2017, 10:32:34 pmNot a single person has stated such nonsense as \"Dimming is not PWM. Period.\" If you have to resort to making things up then your argument is a lost cause.As for you PWM AC waveform doubling the power dissipation in the 10R resistor, why do you think this is acceptable? Do you believe that mass produced LED lamps are all sufficiently over-engineered that you can ignore this?"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2017, 01:06:42 am",
"content": "Quote from: Hero999 on November 13, 2017, 12:49:26 pmSo you say that someone who offers alternate solution for consideration, actually creates \"pages of useless information, which is totally irrelevant to the original poster's question\". With emphasis on \"totally irrelevant\".QuoteAre you serious? How many times didyouoffer something that differ from original poster's plans? - Shall we count? Or maybe you did not offer anything useful, just denied everything you did not agree to?"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2017, 01:29:16 am",
"content": "Quote from: mikerj on November 13, 2017, 01:18:05 pmWell, Hero999 stated: \"It supports TRIAC dimmers, not PWM! They are not the same thing!\". In my opinion saying \"Dimming and PWM are not the same thing!\" (pay attention to exclamationsignmark) is the same as \"Dimming is not PWM\".QuoteI did agree that this is not acceptable. Perhaps you missed that (as usually happens here in thisforumthread):Quote from: ogden on November 12, 2017, 09:39:16 pm"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2017, 01:45:38 am",
"content": "Quote from: ogden on November 14, 2017, 01:06:42 amActually I did good service to thread - created special attention to square wave inverters which are not compatible with some LED bulbs. I doubt that 5$ inverter mentioned by original poster, is pure sine wave one. Disregarding this fact you did offer your ring oscillator. No further comments..."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 14, 2017, 05:20:21 am",
"content": "Quoteits ok Hero999, not your faultI request the other poster to keep discussion to target the plan of mux on the AC line .Let us not go deep into LED drivers and million inverter design. Then it will be like making a chair for 2yo to 90yo with a size that fits all .We are engineers , seek to make viable products not science explorer .-some good news here!!! -The plan works by unloading the invertera small inverter that used to flicker after 15watts now happily taking 25W , pretty amazing bright lights .i am too lazy to make lux meter but compared lightof 1 bulb with MUX and without MUX .Did it save power ?Not much,9watter was pulling 800mA DC25watts load was showing 600mA / per 5watts draindid the lamps over heat ?NOi wish someone could fund me for a patent!Many experts cant achieve to a solution because they lose focus , so it is better the discussion can limited to reach some solutionthese are the parameters for a BETA of the AC MUX=============- Approx square wave ( a little different in my case ) inverter , take frequency 10khz-target is to get atleast 4 bulbs on 10w inverter-all bulbs are SMPS ( no future tech and , cap dropper)===================================There are 2 ways-simulation model-real oneSecond one will save time initially"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2017, 08:53:54 am",
"content": "Quote from: ogden on November 14, 2017, 01:06:42 amYou didn't contribute any schematics, simulations or ideas to the thread. I posted a simulation which demonstrated what happens to the input stage of a mains LED, when driven with various waveforms. All you did was derail the thread with nonsense about it being fine to overstress parts, dimmable lamps and PWM and phase control being the same thing.Quote from: dave_j_fan on November 14, 2017, 05:20:21 amYou can't rely on your eyes to make quantitative measurements. A lux meter is the only way to perform objective tests.I suggest doing long term trials. Just because they're SMPS, it doesn't mean their reliability won't be affected.Have you looked at the output current and voltage waveform of your inverter with an oscilloscope?"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2017, 11:49:33 am",
"content": "Quote from: Hero999 on November 14, 2017, 08:53:54 amI did. Very early in this thread I said: \"I would run all the LED bulbs in parallel - to save on wiring in many installations and create10W PWM-dimmable AC square wave inverter with input current limiter. Current limiter as safeguard against inverter overload and output short. \"QuoteYou posted simulation which uses inverter of infinite power just to prove your uneducated point, ignoring fact that original poster mentioned 10W (in the topic of this thread). If we take in account limited power of the inverter which can sustain let's say 1A max output current, then \"parts overstress\" picture changes dramatically and inrush resistor dissipates just 155mWaverage during 1sec of simulationwhich is few times less than nominal which you put at 500mW. Simulation attached.QuoteIt is actually you who are spilling nonsense all over this thread by literally attacking me with sentences like this, providing misleading \"facts\" using simulations that proves nothing more than how incompetent or careless you are. I do not recall saying \"it is fine to overstress\". I said - if everything is designed properly then nothing will blow up meaning there will be no parts overstress."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2017, 07:52:04 pm",
"content": "For those who still believes that square wave is much worse for LED bulb than sine, I offer to consider that bulbs shall be designed to withstand power-on at any phase angle of AC mains including max peak voltage, otherwise they will blow-up nearly every power-on. Best and worst case dissipation of inrush resistor results for AC mains sine attached. Best case obviously - to show that it gives result we already know, 0.5W @ 1sec.Worst case is much more interesting.. because it's 2.49W is pretty close to \"LED blown-up by square wave\" simulation result of 2.54W"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2017, 08:13:47 pm",
"content": "Quote from: dave_j_fan on November 14, 2017, 05:20:21 amSorry, I had to correct misleading information Hero999 provided here - regarding LED bulbs on square wave supply.AC line? Do you have \"pure sine wave\" inverter? Please show it's output waveform on the scope so we all know what you have."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 18, 2017, 05:22:44 pm",
"content": "Quoteno issue . I hope to know additional possibilities .Q.Will the driver less LED help me to cut power usage"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 18, 2017, 06:39:22 pm",
"content": "Quote from: dave_j_fan on November 18, 2017, 05:22:44 pmMost likely not. If driver-less bulbs would be universally more effective- they would dominate market, but this is not the case. All the hi-end LED bulbs are equipped with some kind of driver. Anyway you shall not rely on assumption. Better search internet for research/reviews which are comparing consumed power versus light output."
},
{
"post_id": "",
"author": "dave_j_fan",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 18, 2017, 07:52:07 pm",
"content": "Quotei was asking if i use AC MUX"
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 18, 2017, 08:25:07 pm",
"content": "Quote from: dave_j_fan on November 18, 2017, 07:52:07 pmAC mux will unlikely change anything regarding various LED bulb efficiency. Frequency of supplied AC voltage instead can change a lot. If you use bulbs at much higher frequency - you are on your own. You shall get precision LUX meter and do your own efficiency measurements for various types of led bulbs."
}
] |
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| true
|
https://www.eevblog.com/forum/beginners/10x-osciloscope-probe-2-2-megaohm-input-resistance-question/
|
10x osciloscope probe - 2.2 Megaohm input resistance - Question - Page 1
|
[
{
"post_id": "",
"author": "BinaryBits",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 01, 2023, 12:11:42 pm",
"content": "I am new with scopes, and i have tried to search the internet, but haven´t found an answer to my question.So i have this Agilent 10073C 10x probe which has an input impedance of 2.2 Megaohm.The specsheet for this probe also says \"2.2 Megaohm input impedance when terminated into 1 Megaohm\"So everywhere i read it says that 10x probes usually has 9 Megaohm input resistance. So if i use this particular probe with my Tektronix TDS220 scope, will the 2.2 Megaohm input impedance affect the readings on the scope, since 10x probes usually has 9 Megaohms, for a total of 10 Megaohms together with the scope, so maybe the scope is \"expecting\" 9 Megaohms when the scope is set to 10x?Or doesn´t the input impedance have anything to do with the times attenuated?Also, does it mean that i can´t measure as high of a voltage with this probe, since the impedance is lower than on the usual 10X probes?I haven´t noticed any obvious differences on the readings compared to my cheapo 1x/10x probe, but maybe i have missed something?So my question is, will my Tektronix scope see the readings through this 2.2 MOhm probe exactly the same way as through any 9 MOhm probe?Thanks in advance."
},
{
"post_id": "",
"author": "alm",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2023, 12:27:01 pm",
"content": "Theprobe datasheetsays attenuation ratio 10:1, so it will look like any other 10:1 probe to your scope. A 10:1 probe with 10 MOhm input resistance is (very simplified) a 9 MOhm resistor in series with the 1 MOhm input of the scope, forming voltage divider that divides by 10.The 10073C has been designed for a lower input impedance. This will have been achieved by putting something like 280 kOhm in parallel with the scope input for a total resistance of about 220 kOhm, and then a 1.98 MOhm series resistance to give a 10:1 attenuation ratio. So the only effect you'll notice is a slightly higher load on your circuit at DC. For maximum voltage check the probe datasheet / manual. There is not necessarily a direct relationship between impedance and maximum input voltage.You'll have to check if the probe compensates to your scope. The probe is specified as compensating to a scope input capacitance of 6 - 15 pF, and from memory the TDS has a higher input capacitance. But then the trimmer caps they use aren't known for their low tolerances, so you might get lucky and if you already have the probe you can easily test this by connecting the probe to the probe compensation output and see if you can trim it for a clean rising / falling edge without overshoot or undershoot."
},
{
"post_id": "",
"author": "HighVoltage",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2023, 03:09:21 pm",
"content": "If I remember right, the Agilent 10073C was the fastest passive scope probe that Agilent offered at the time.To get the fast rise times, the resistance was lowered.https://teledynelecroy.com/doc/probes-probing"
},
{
"post_id": "",
"author": "Wallace Gasiewicz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2023, 04:17:05 pm",
"content": "alm has a good pointYour scope will not work correctly with the wrong capacitance probe. Your scope has a 20 pF input, your probe has a max 15 pf spec.Maybe the comp will work to 20, as alm suggests.If the probe is not matched your square wave will not be square and your higher freq responses will not be accurate. Things like rise time will not be accurate at all.But the probe will still \"work\"The resistance of that particular probe is not that important, except for very accurate readings.The cheap Chinese probes I have bought are just fine and in some ways better than the much more expensive HP probes that I have ( also made in China ) I do not recommend the switched probes 1X-10X. Besides the probes internal problems, operator problems like leaving the probe in 1X mode while sampling high volts may damage the scope. Don't ask me how I know this HA!! People do not use 1X much at all anyway.The important thing is that the scope capacitance matches the probe capacitance.After you are sure the scope works well, I would buy a pair for your nice new scope."
},
{
"post_id": "",
"author": "Eraldo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 02, 2023, 04:28:10 pm",
"content": "Leaving aside the capacitance problem, if you were to plug that probe into a tektronix (1meg imput impedance) you would basically have an x3.2 probe since x10 probes are just voltage dividers (the ratio between the measured voltage and displayed voltage in this case is 3.2).So if you were to set the oscilloscopes internal probe selection to x1, you would just need to multiply to 3.2 every voltage value of interest to find the real voltage you're measuring. (correct me if i'm saying something wrong here since i'm not sure if the true rms voltage can be found this way or for anything else)so in the end it would work but it would be very inconvenient because of the reason above( it not being a standard value like x10 or x100) and the oscilloscope doesn't display the correct values neither in x1 nor in x10. Not sure if there is a feature where you can set your own ratio of resistors in your device though of if it even exist as a feature in any other oscilloscope.Yeah just read the first comment of alm or a quick explanation below"
},
{
"post_id": "",
"author": "alm",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2023, 05:02:04 pm",
"content": "Quote from: Eraldo on May 02, 2023, 04:28:10 pmNo, the ratio between the measured voltage and displayed voltage would be 10, since it's specified as a 10:1 probe when terminated in 1 MOhm. Read the specs more carefully."
},
{
"post_id": "",
"author": "Eraldo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 02, 2023, 08:08:00 pm",
"content": "Yeah i get it now that i reread your first comment again. So they are basically not only putting a resistor in series but one in parallel with the scope too. That makes more sense. First time i hear it though, and it being specified as only \"2.2meg imput resistance\" in the datasheet was a bit misleading (they didn't even add one of those notes at the end of the page)Thanks for correcting me"
},
{
"post_id": "",
"author": "BinaryBits",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 13, 2023, 09:41:14 am",
"content": "Thanks, that clarifies it. I already have this probe, i got it with the TDS220. The trace looks normal when connected to the 1kHz calibration signal, i had to compensate the probe a bit though.But i haven´t used the probe for any other measurements, so i don´t know if it would start showing erroneous readings when making real measurements?Also, the voltage reading shows 5V, when connected to the calibration signal, as it should do.Exactly, the compensation range is 6-15pF on this probe according to the datasheet.Thanks for your answers, that was helpful."
},
{
"post_id": "",
"author": "pdenisowski",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 13, 2023, 10:51:43 am",
"content": "I made a video that discusses how 10X probes work (including the voltage divider part) and another on probe compensation)"
}
] |
2025-10-17T16:54:41.141252
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/10x-probe-compensation-looks-different-depending-on-view/
|
10x probe compensation looks different depending on view - Page 1
|
[
{
"post_id": "",
"author": "optimizer",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 17, 2017, 05:46:59 am",
"content": "i just got a dso nano v3 and a 10x probe. when i use the probes that came with the nano the wave out looks like a proper square wave, and when i use the 10x probe set to 1x. as soon as i flip the switch to 10x the square isn't properly compensated so i adjust it to look as good as it can. when i \"zoom in\" on the wave it looks like it isn't compensated anymore. i redid the compensation in this zoomed in setting, but then a different view looks like it isn't compensated anymore. attached pics are with the 10x compensated to the zoomed in view."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2017, 06:33:46 am",
"content": "Welcome to the forum.Hmmm.The first two shots are spot on and as one would expect.Does it have an Autoset ? Does that change the result ?There's a few things I want to point out but it does indeed seem something's not right.Scopes all have a spec of capacitance in their inputs, usually 10-20 pF and the compensation adjustment range of any probe need fall within it.Probes only need be adjusted for their 10x range.Input attenuation need match the probe to ensure on-screen measurements are correct, yours aren't.Zooming of the vertical axis in the manner you have can give unexpected results if the offset limits are breached."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2017, 09:02:59 am",
"content": "What you're doing is setting a capacitor on the probe, so that it complements the capacitance of the scope. (The probe is a resistor divider at low frequencies, and a capacitor divider at high frequencies.)As you switch ranges on the scope, switches or relays connect different dividers between the probe and the input amp / ADC. These dividers are themselves like probes: resistor and capacitor dividers.When you probe a probe (so to speak), you only get the right response when all the resistor and capacitor dividers match up. If the dividers aren't perfectly matched, then the capacitance of the scope can vary with setting, which means the probe compensation needs to vary as well.At a glance, I don't see any specifications on that thing even mentioning capacitance, so, I'm betting on poor design.Tim"
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2017, 12:41:47 pm",
"content": "Some useful application notes notes -www.tek.com/dl/51W_30013_0_MR_Letter_0.pdfhttps://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiUqbvomMnRAhVIPiYKHbYfDQ0QFggiMAE&url=http%3A%2F%2Fwww.tek.com%2Fdl%2FProbing%252520Techniques%252520for%252520Accurate%252520Voltage%252520Measurements%25252051W_60161_1_HR_Letter.pdf&usg=AFQjCNEY4Xc9dBkBMCXP2bFyqTGr3hGggg&sig2=2r_zt-vPRHfQSCjZm-ygoQwww.newark.com/pdfs/techarticles/tektronix/FFM.pdfRegards, Dana."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2017, 01:01:15 pm",
"content": "The schematic for the DSO Nano V3 is available online and shows a toy input stage with adjusted compensation on only 2 ranges out of 5."
},
{
"post_id": "",
"author": "macboy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2017, 02:35:06 pm",
"content": "I once put together a DSO138 kit to give to a family member going into EE. It had the same issue: input capacitance was not consistent across voltage ranges. This meant that the probe compensation needs to be adjusted every single time that you switch ranges. (FWIW the DSO138 doesn't come with a 10x probe, and this isn't an issue with its alligator clips)."
},
{
"post_id": "",
"author": "optimizer",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 17, 2017, 05:54:12 pm",
"content": "thanks for all the replies. i knew the nano was a low level scope when i bought it, but i'm really only using it for setting gain levels in my car. i guess i was wanting to know if there was a standard view setting in which to compensate a 10x probe or if it needed to be done for whatever view setting you were going to be using for your source. if i need to compensate it for every different view, how can i get my square wave source up to the level that i'm going to be testing? one of my amps was putting out about 50 volts before it clipped."
}
] |
2025-10-17T19:04:57.740999
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/11-transformer-winding-confusion/
|
1:1 Transformer Winding Confusion - Page 1
|
[
{
"post_id": "",
"author": "made2hack",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "April 04, 2017, 10:28:38 am",
"content": "Hello all,So I am again confused as to the winding of my Isolation transformer. The transformer will be a 1:1 Isolation transformer.Assume the following - Max Load 2A (both primary and secondary) ( In reality, the primary will probably see 2.1 A - considering 95% efficiency).I am using 0.9mm diameter (AWG 19) magnet copper wire. This wire has 26.41 Ohm / km. I've tentatively calculated that I will need approximately 110 Meters of wire on each winding. So, as a result, total copper resistance will be on the order of 2.9 Ohms on each winding (Let's approximate to 3 Ohm for now).What is my voltage drop? Is it V = IxR ? Is it V = IxIxR ? (As is in Power / Copper Loss). Do I drop 6V per winding? Or do I drop 12 V per winding? I know technically in AC you use E=IxZ but I don't have the data or patience to calculate Impedance and what not.Questions:1 - Where do I account for voltage drop? In primary? In secondary? Both since it is 1:1 winding?2 - Do I care about Copper Loss or have I taken care of copper loss in the voltage Drop?A similar sized transformer (approx 300VA - 350VA) from the manufacturer where I got my winding states full load copper loses of either 23.5W for the 300VA or 28.6W for the 350VA. If I am dropping 6V per winding, my copper loss will be 18W per winding or 36W total ? If I am dropping 12V per winding, my copper loss will be 36W per winding or 72W total ?Such is my confusion."
},
{
"post_id": "",
"author": "MagicSmoker",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 03:02:55 pm",
"content": "I already answered your question about voltage drop in the other thread you started.... I also addressed the issue of one of the AC reactances that affect transformer performance: leakage inductance.Quote from: MagicSmoker on March 30, 2017, 02:50:23 pm"
},
{
"post_id": "",
"author": "made2hack",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "April 04, 2017, 03:16:23 pm",
"content": "I think I missed it. But it's starting to make sense now. Thanks"
}
] |
2025-10-17T18:59:28.439425
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/110-ac-dpdt-latch-relay/
|
110 AC DPDT latch relay - Page 1
|
[
{
"post_id": "",
"author": "tubejim101",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 08, 2011, 11:43:42 pm",
"content": "Have a solar panel running to a batter. Have an inverter for the battery.So I would like to tape into one of my house ceiling lights.The idea would be to have a microcontroller check the battery.If their is enough \"juice\" in the battery, run the light off the battery.If not, then run the light off the city/house power.Can anyone recommend some kind of latching AC relay that I can control with my microcontroller?Hopefully, one that does not cost to much."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 08, 2011, 11:53:42 pm",
"content": "You shouldn't mess with mains wiring unless you are an electrician, or unless you really know what you are doing.Unfortunately, asking this question means you don't really know what you are doing. Best to stay way from the mains. Use a separate lamp, like a table lamp or standard lamp, and power this solely from the inverter. Don't make any connection to the mains wiring."
},
{
"post_id": "",
"author": "tubejim101",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 09, 2011, 12:21:00 am",
"content": "Quote from: IanB on October 08, 2011, 11:53:42 pmHere in the states we are encouraged to do our own work. We have many warehouse like stores that you can buy everything you need to do the house wiring. They will assist you with any questions and even have classes you can take in the stores. Only thing, is it is \"old school\" for the most part. Most house electricians don't know what a microcontroller is."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 09, 2011, 01:11:36 am",
"content": "Do you have a Fry's near you? Last time I was in there they had a whole range of solar panels, charge controllers, batteries, mains switching interfaces and everything you need for a home solar power system. All properly designed with the right safety certifications and installation instructions. Take a look there."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 09, 2011, 02:22:08 pm",
"content": "Quote from: tubejim101 on October 09, 2011, 12:21:00 amBecause they don't need to know what a microcontroller does, the same as a digital designer doesn't need to know about wiring regulation.Would you be able to work out the fault circuit current of your mains supply or work out the derating factor for PVC cables buried under thermal insulation? Are you aware of the requirements for connecting an inverter to the grid in your country?"
},
{
"post_id": "",
"author": "bilko",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 09, 2011, 02:26:31 pm",
"content": "Quote from: tubejim101 on October 08, 2011, 11:43:42 pmWhy can't you use the micro to latch the relay ?If you use relay logic you can very easily create a latching circuit, does the relay circuit have to survive a power cycle ?"
},
{
"post_id": "",
"author": "tubejim101",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 09, 2011, 03:17:17 pm",
"content": "Quote from: yachtronics on October 09, 2011, 02:26:31 pmJust planning on running house ceiling lights. So the power cycle should not be an issue."
},
{
"post_id": "",
"author": "bilko",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 09, 2011, 03:52:52 pm",
"content": "Some properties have a standby generator in case of mains power failure. The safety requirements would be similar. There are issues in not back feeding the supply if you lose utility power. I would do as another poster suggested earlier, that is to run a totally separate light, standard lamp e.t.c.The problem is if you interface to your domestic lighting and do not have the correct protective measures, you could end up getting in trouble or getting sued.If you use a relay with DPDT contacts the commons would connect to the lamp, the nc contact to utility power and the no contacts to your solar powered inverter. The system would work OK, but in no way would I recommend that you connect the system up like I described. Should the relay fail or the contacts weld together there could be significant problems.To do the job properly and safely requires a lot more thought and as others have said, you need to follow local regulations including fitting safety equipment."
},
{
"post_id": "",
"author": "Rufus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 09, 2011, 03:56:13 pm",
"content": "Quote from: tubejim101 on October 09, 2011, 03:17:17 pmUnless your mains power is really expensive or your batteries are really cheap the wear on batteries will cost you more than the electricity you save."
},
{
"post_id": "",
"author": "Jimmy",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 12, 2011, 04:04:50 am",
"content": "You don't need a microcontroller to check batt voltages you can just use a LM3814 in bar mode to check voltage with some magic then drive a relay with that.Assuming that you are allowed to modify mains wiring where you are.With the Relay you would wire the common to the Light the NC to the House live wire and NO to the Inverter Live wire.Then when your circuit gives power to the relay it will change to inverter power. This way if your circuit breaks you will have mains power lights. This would act like an automatic change over switch. If wired correctly there is physically no way you can back feed power into the grid.Or you could just put some 12v led lights in your room and and have a 12v mains psu as backup power that automatically takes over once batteries drop below a set voltage. You can then use the inverter to run other stuff."
},
{
"post_id": "",
"author": "PetrosA",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 13, 2011, 02:54:14 am",
"content": "If you're in the US, I can't think of anything in the NEC that would allow you to do this for less than a few hundred dollars - legally, that is. When you power mains fed loads from a transferred battery powered source, it's what's called a Separately Derived System (the same as a permanently mounted generator). If you intend to do this, you better read up on the requirements for SDSs. It will mean installing separate grounding electrodes, panels, transfer switches, etc. Big money if you want to do it and have insurance cover a loss if something goes wrong."
},
{
"post_id": "",
"author": "bilko",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 13, 2011, 11:16:56 am",
"content": "Quote from: Jimmy on October 12, 2011, 04:04:50 amHave you ever seen relay contacts weld ?That is why I suggested the method in the previous post and then scored through. I would suggest that the OP speaks to his insurance company because if his house burns down or if a utility worker gets electrocuted then he will be in big trouble.Not wanting to pour water on the idea but there is a right way and a wrong way of doing things."
},
{
"post_id": "",
"author": "Jimmy",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 13, 2011, 11:58:35 pm",
"content": "QuoteYes I have seen many relay contacts wield together. About 8 years ago I had the pleasure of replacing about 80 relays in a 240v emergency backup system that failed to operate correctly. This did not create a fire only incorrect operation.QuoteThat is why I suggested replacing it with a 12v system. In most places you can burn your house down if you get a permit.QuoteIt a utility worker gets electrocuted form this it is his own fault for failing to isolate all sources of supply and failing to test before you touch. If the contacts on the wield together and the power goes out the inverter will not start supplying power to the grid only your lights. It will only supply back to the grid if there is a short circuit which would quickly blow the fuse in the inverter."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 14, 2011, 05:27:27 pm",
"content": "Quote from: Jimmy on October 13, 2011, 11:58:35 pmWhy on earth would a 12V system be less of a fire risk?That makes no sense. In reality a 12V system will probably pose a greater fire risk than the mains. Batteries can catch fire and hydrogen gas can cause explosions. You may also need to replace the wring and switches. The current in a 12V system will be 20 times greater than the equivalent 240V system, causing the power dissipation in the cables to increase 400 fold which may cause a fire if the cables aren't suitably rated. Fortunately the cable in most modern installations is suitable overrated but you should check it, just to be safe. You could also increase the voltage to 48V to reduce the current four fold.As far as regulations are concerned, in the UK the fact that it's ELV will not absolve you from abiding by the wiring regulations which also cover wind power, battery and PV installations, regardless of the voltage. You still need to use suitable fuses or circuit breakers and the correct cable. The only really difference is you don't need to use an RCD if it's 120VDC or 50VAC."
},
{
"post_id": "",
"author": "NiHaoMike",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 17, 2011, 01:32:11 am",
"content": "Quote from: PetrosA on October 13, 2011, 02:54:14 amIf a plug in solution would work, a UPS nearly does just that. You'll need to somehow hack it to use the mains as a backup."
}
] |
2025-10-17T20:38:05.907724
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/110-volt-microwave-fan-with-three-terminals/
|
110 volt Microwave Fan with three terminals - Page 1
|
[
{
"post_id": "",
"author": "vigsgb",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 26, 2014, 06:59:05 pm",
"content": "I am new and recently ripped apart a microwave and yes I did discharge the capacitor prior to ripping into it. Nope I am not planning on messing around with the magnetron or high voltage transformer. With that out of the way I have looked at the cooling fan and cannot find any information on how to hook it up... I see three terminals and decided to just stick mains power into two of the terminals and yep it fired up...but the windings got very hot and quickly. So I was wondering how do I tell which terminals on the fan to hook up? The fan is a 120 volt 60 Hz... Can't find any specs online."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2014, 07:26:29 pm",
"content": "Use the 2 outermost as connections. The fan often has a winding used to run the turntable motor, which typically runs on 24VAC or 43VAC. Check DC resistance and use the 2 with the highest resistance between them. That will be the outermost ones in most cases. If you look carefully one will have 2 wires connected that runs into the winding. Do not use that one."
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2014, 07:36:03 pm",
"content": "It's possible it's a 2 phase AC motor, and the 'motor run' capacitor (this creates the phase shift for the second coil) is elsewhere - although I can't think what benefit there would be to using this type of motor in something this small.Can you post a pic?"
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2014, 07:40:04 pm",
"content": "Never seen that in a microwave, only a shaded pole unit. The turntable is invariably driven off the fan supply though to cut copper cost in it."
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2014, 07:45:21 pm",
"content": "Yeah SeanB, I can't think why they would either - I haven't had too many microwaves apart though."
},
{
"post_id": "",
"author": "vigsgb",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 26, 2014, 07:49:12 pm",
"content": "I see that the middle connection does indeed have two wires going into the windings and the two outter terminals have the most resistance. After hooking up the mains to the outter connection it no longer heats up and I get 24 volts a.c. from the center terminal. Thanks much... never thought it was to run something else. I will take a few pictures and post."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2014, 09:36:29 pm",
"content": "Wow, I never thought they would integrate a transformer and motor into the same part.I've opened a few microwaves in the past and have never seen this before.Please note that the 24VAC is not isolated from the mains so all connections to it should be properly insulated."
},
{
"post_id": "",
"author": "vigsgb",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 27, 2014, 03:51:16 am",
"content": "Quote from: Hero999 on January 26, 2014, 09:36:29 pmGood point I did notice that when testing I was able to get the 24 volts a.c. when I touched the meter to mains ground."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2014, 04:42:27 am",
"content": "Turntable motor draws a low current, and winding it to full mains uses a lot of copper. As the losses in the gear train are more than the power it delivers using a lower loss in the motor is good, and using an existing core and winding just makes good sense."
}
] |
2025-10-17T20:09:29.904442
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1104x-e-and-esd()/
|
1104x-e and ESD(?) - Page 1
|
[
{
"post_id": "",
"author": "Sendi",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 28, 2022, 10:15:32 pm",
"content": "Hello,recently i bought siglent 1104x-e and i noticed that it sometimes restarts for example whenI plug cable into usb-b socket (device mode) even if other end of cable is unpluggedWhen i plug that cable to the pcWhen i touch any metal (ground) part on the scope and there is a plug in USB-B socketWhen nothing is plugged to the USB-B socket and i touch metal pendrive plugged to the back usb portAlso sometimes if i touch metal pendrive plugged to front usb it semi-crashes - usb stops working and I cant turn off scope with button but it reacts to other buttons and knobs.Touching doesnt even have to be by hand, its triggered sometimes by multimeter probe. I also tried few usb cables with same resultsBeside that scope seems to work fine.What i want to know is if this is faulty device or is it just lack of esd protection on my side.I mean i was using Rigol 1054Z in the past and didnt have any problems like that. That makes me think this new scope is too sensitive.Thanks for helping"
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 28, 2022, 10:20:12 pm",
"content": "Sounds like a grounding issue. Have you checked the grounds going to the scope and the PC?"
},
{
"post_id": "",
"author": "Sendi",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 28, 2022, 10:29:58 pm",
"content": "PC is grounded and scope was tested both with and without earth. But situation with PC connected is only one of several others that problem appears"
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 28, 2022, 10:37:52 pm",
"content": "Both my Siglent scopes are rock solid. How new is this and where di you buy it?"
},
{
"post_id": "",
"author": "Sendi",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 28, 2022, 10:44:29 pm",
"content": "In Poland from \"authorized distributor\".FPGA version 2021-11-08,Hardware version 09-06.It was calibrated in 12.2021"
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 28, 2022, 10:56:47 pm",
"content": "I would contact the distributor. Siglent have a 30 day return policy so if they are an authorized distributor, they should honor that.Have you installed the latest firmware?"
},
{
"post_id": "",
"author": "Sendi",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 29, 2022, 09:52:53 pm",
"content": "Yes I did. Nothing changed"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 29, 2022, 09:57:12 pm",
"content": "Quote from: BillyO on December 28, 2022, 10:20:12 pmGround is for safety, nothing to do with ESD immunity. I would return the scope if possible since it seems to be marginally working."
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 29, 2022, 11:02:31 pm",
"content": "Quote from: wraper on December 29, 2022, 09:57:12 pmThink about what I said. Think about the situation. Think about the leakage current that can (will) develop when an ungrounded device with a SMPS is connected via a communications cable to a grounded device. Unlike linear supplies with transformers, SMPS can generate fairly high voltages WRT earth/ground. These voltages can manifest anywhere in the ungrounded device with an SMPS, especially in the output voltages of the supply. These are then used to power all components of the device, including the USB chips. So, when a floating device is connected to a grounded device via a USB cable, strange things can, and do, happen.In other words, his problem mightNOTbe ESD. It might be improper grounding.Proper grounding isNOTjust for safety. Next time, just think.Oh, and if you think grounding a large floating piece of equipment like a scope though a flimsy USB cable though a computer will not make it more ESD sensitive, you need to give you head a shake. But thanks for your input."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 30, 2022, 07:40:45 am",
"content": "First of all earth wire has too much of length and induction to offer protection against ESD as it causes extremely fast impulse (nanoseconds). Secondly usual ESD discharge to scope ground must not cause malfunction if device is not faulty.QuoteSMPS more likely to have Y interference suppression caps between primary and earth which causes more current leakage. However it has nothing to do with device rebooting if not faulty. Again, earth wire is for safety only, devices without earth connection require stronger insulation from mains voltage. There could be an argument if reboot happens only when plugging USB cable but it's not only that.QuoteLack of earth connection may be a contributor but not the root cause. In case of the scope the major risk is damaging a circuit which you measure due to half of mains potential on earth alligator clip due to discharging Y interference suppression capacitors into a circuit. If scope is not faulty, lacking earth connection should not cause device malfunction. Normally it has no way to impact internal circuit of the scope. The only way scope can reboot on occasional ESD event of not too high energy is if it's already marginally stable and reasonably small electromagnetic disturbance sends it into reboot.The only thing I suspect without scope being faulty is an out of spec USB cable with no shield or some connection lacking, or USB port with no proper GND connection (either on scope or PC side) which causes extreme voltages going into data lines which causes CPU malfunction and watchdog resetting the scope."
}
] |
2025-10-17T17:01:17.863724
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/110v-60hz-hakko-fx-888d-with-a-step-down-transformer/
|
110V-60Hz Hakko FX-888D with a step down transformer? - Page 1
|
[
{
"post_id": "",
"author": "HakkoPlease",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 11, 2020, 09:35:53 am",
"content": "Hey guys!I was looking to buy this soldering station and realized very quickly that it's 110V 60Hz (obviously, as it's on Amazon US). At first it didn't faze me, because I figured that I could simply utilize a step down transformer. However, it very quickly dawned on me that while I would be converting from 230V to 110V, the frequency will remain 60Hz instead of 50Hz.I find mixed answers as for whether that'd be a problem with a soldering station or not. I looked up the topic on the page's Q&A section and came up with. Notice how the top one suggests the frequency would be an issue, while the 3rd one claims to be utilizing a transformer and have no issues whatsoever.I then proceeded to browse Google and fortunately enough was able to find you guys, and more specifically,a thread that seemed to be addressing the very same topic(the question is first brought up towards the end of the 1st page, but the majority of the discussion is at the second page). The opinions seem to be split and The guys who have discussed this are no longer active (I've checked, so I can't ask them for a conclusion), so I've decided to make an account and ask you guys!While I'm not from the UK, I would also be needing 230V and 50Hz (we do use different plugs, though), so if yo but I didn't bother looking up whether the transformer I had in mind would fit, because at this moment it would be pointless, as I would first have to figure out the frequency debate.I enjoy free shipping on Amazon US, so I'd only have to pay exactly $123 ($99.42 plus $23.58 £23.73 Import Fees Deposit) for the 110 V 60Hz Hakko (and the transformer I thought I'd get would only cost an additional ~$17 or so for a 100W step down transformer).The same UK Hakkowould cost me $213.35 (£112.70 + £26.87 for Postage & Packing + £23.73 Import Fees Deposit). That's the main reason I was considering a step down transformer.One of the comments on the second page of the forum thread I linked does explain that 50Hz devices are more expensive to make, but to be honest, everything on Amazon UK seems way more expensive, so it's obviously not the only reason for the huge price gap. While looking up the frequency issue, I've been trying to find another location to purchase the 230W Hakko, but I haven't had luck so far.Would love to hear your guys' input.Thanks!"
},
{
"post_id": "",
"author": "GerryR",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 11, 2020, 12:21:49 pm",
"content": "If you look at the attached diagram, you will notice that the Hakko internal transformer can be wired for anything from 100V to 240V using \"part 8,\" which includes the fuse. The only thing you have to worry about between 50 Hz and 60 Hz operation is the transformer inductance, which might overheat on 50 Hz operation. Just a guess, but I would think that the transformer in the Hakko was designed to operate at either frequency, thereby addressing both markets, as evidenced by the array of voltages it is designed to take.I would buy the 120V version and a power cord for your outlet, open it up and rewire it for 230V or 240V and run it with either 50 or 60 Hz. And don't forget to change the fuse to the correct value for the new voltage. JMO."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2020, 02:01:51 pm",
"content": "No, the internal transformer can't be wired for different voltages, hence why different part numbers are specified for different voltages.Yes, it will work perfectly fine from 110VAC at 50Hz. I have one myself running from a small step-down transformer. I would recommend getting the correct voltage Hakko, rather than using a transformer because it's much easier and takes up less space."
},
{
"post_id": "",
"author": "GerryR",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 11, 2020, 03:07:32 pm",
"content": "Zero999 is correct. I opened mine up and the transformer is specifically marked and wired for 120V. So there is a different transformer and a different fuse board for each configuration. A picture of the fuse board is attached."
},
{
"post_id": "",
"author": "JackJones",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 11, 2020, 03:22:54 pm",
"content": "You can get the higher voltage version from Batterfly for ~100€ plus shipping + VAT if you don't want to mess around with a separate transformer.They don't seem to give a quote for shipping to Israel but you could always ask.I bought my Hakko from there a few years ago. It's even the (in my opinion) nicer looking silver version:https://www.batterfly.com/shop/en/hakko-fx-888d-silver"
},
{
"post_id": "",
"author": "HakkoPlease",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 11, 2020, 03:51:18 pm",
"content": "First of all, thank you Gerry, Zero and Jack guys for the replies!Quote from: JackJones on January 11, 2020, 03:22:54 pmThank you! I'm obviously familiar with this vendor, after having conducted such a comprehensive research (you guys have mentioned them in the past, as well).I mailed them earlier, inquiring about the lack of shipping options I was prompted with, in hopes that we could work something out manually. I'm awaiting their response now, but thanks regardless for looking out!Quote from: Zero999 on January 11, 2020, 02:01:51 pmMy initial plan was to go withthis cheap, 100W step down transformer. However, as you mentioned yourself, I'd obviously rather get one that is already adjusted to the correct voltage. My best option and best case scenario would be a positive answer from Batterfly. As they say, though; hope for the best and prepare for the worst.Not only that, but someone else has told me:QuoteBasically implying that if I'd be going down this path, I better get a higher wattage transformer (if he's accurate about the potential x5-10 jump, the transformer will be quite expensive and no longer worth it).Thoughts?Thanks again,"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2020, 09:06:18 pm",
"content": "A 100VA transformer is more than enough. The Hakko doesn't draw a large current spike, when turned on from cold. The heating element only heats to a few hundred degrees Celsius. It's not like a large halogen lamp which gets to a few thousand degrees."
},
{
"post_id": "",
"author": "HakkoPlease",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 13, 2020, 09:55:48 am",
"content": "Hey guys,Just wanted to update that Batterfly got back to me and fortunately enough, have confirmed that I'll be able to have it delivered!Regardless, Zero - thanks for letting me know that had things come to that, it would have been okay to use a transformer."
}
] |
2025-10-17T17:57:38.749919
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/110v-in-uk/
|
110v in UK - Page 1
|
[
{
"post_id": "",
"author": "HomerA",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 07, 2015, 10:04:02 pm",
"content": "Hi all,this is my first post here :-) and forgive this stupid question, but I live in the UK (240v) and I can get hold of a cheap (2nd hand) Antex soldering station. Is there any way to convert it to run on 240v?Many thanks"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 10:07:12 pm",
"content": "Quote from: HomerA on January 07, 2015, 10:04:02 pmTwo possibilities:a) Use a 240 V/120 V mains step down transformerb) Open up the soldering station, examine the transformer inside it and replace it with an equivalent transformer having a 240 V primary"
},
{
"post_id": "",
"author": "HomerA",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 07, 2015, 10:12:34 pm",
"content": "Thanks for the response. Just checked step down transformers and they are between £80 and £100 so not really an option.Could try the second option but not sure where to get the correct transformer.. Will check this out."
},
{
"post_id": "",
"author": "helius",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 10:20:46 pm",
"content": "Many types of equipment have dual-voltage transformers even if there is no voltage switch on the panel.This type of transformer has two primary windings, and is wired with the windings in parallel for 120V, series for 240V."
},
{
"post_id": "",
"author": "HomerA",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 07, 2015, 10:31:56 pm",
"content": "thanks for the reply Helius.this is the Antex 660-tc. So does that mean I can just change the internal transformer connections (bit of soldering) and it will work on 240v? :-)"
},
{
"post_id": "",
"author": "Howardlong",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 10:40:15 pm",
"content": "FWIW Maplin have a 300W step down transformer for 30 quid. Order code VR05F.I don't have this exact one, but I did buy a similar one from Maplin about 20 years ago and it's still regularly in use today. I'm not often one to sing the praises of Maplin, but in this case it wasn't a POS.Be careful of underestimating current and power draw. They have a 100W wall wart style comverter too, about 23 quid. That may be enough, you'd have to check your soldering station spec. Personally I'd spend the extra £7."
},
{
"post_id": "",
"author": "krivx",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 10:40:45 pm",
"content": "Quote from: HomerA on January 07, 2015, 10:12:34 pmI would look for a used transformer - they are very common on the used market as most construction site tools run on 120VAC. I bought a 300W step down transformer for 15euro a couple of years ago."
},
{
"post_id": "",
"author": "HomerA",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 07, 2015, 10:47:51 pm",
"content": "again thanks for respondingjust done some research after Helius coment and found this video.looks like the transformers have both connections on? :-)"
},
{
"post_id": "",
"author": "katzohki",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 11:06:06 pm",
"content": "Quote from: HomerA on January 07, 2015, 10:31:56 pmPretty much. Make sure not to use the soldering iron on itself!!!!"
},
{
"post_id": "",
"author": "helius",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 11:26:35 pm",
"content": "Yes, it looks like the xfmr in that video has dual primary windings. When wired for 110V, the live wire from the switch will be connected to the same side of both windings. What you want for 220V is to make it connect to only one winding, with the two windings in series. Don't reverse the direction from live-to-neutral of the windings.It should be easier to understand with a picture."
},
{
"post_id": "",
"author": "ConKbot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 11:31:26 pm",
"content": "Quote from: HomerA on January 07, 2015, 10:12:34 pmhttp://110world.co.uk/1kva-powertool-transformer-p-100.htmland if they are commonly used for power tools on work sites, would there be a chance you could pick one up at a pawn shop? £46"
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2015, 12:21:19 am",
"content": "Many older consumer electronics have dual voltage transformers. These could be connected to form an auto transformer. Lots of things have a transformer rated between 50 and 100W, enough for an iron. I'm in 120V world. I would have no trouble creating 240V for free."
},
{
"post_id": "",
"author": "LukeW",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 08, 2015, 04:26:06 am",
"content": "Quote from: katzohki on January 07, 2015, 11:06:06 pmOnly for expert skilled users"
},
{
"post_id": "",
"author": "miguelvp",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2015, 06:31:15 am",
"content": "Quote from: LukeW on January 08, 2015, 04:26:06 amAnd just to note, he is only kidding. The tip is hopefully grounded so touching anything other than ground will short the iron and probably the operator."
},
{
"post_id": "",
"author": "HomerA",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 08, 2015, 09:40:54 am",
"content": "Thanks all for your comments. I have bought the iron and I will give an update once I have converted it and got it working"
},
{
"post_id": "",
"author": "Wilksey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2015, 07:23:33 pm",
"content": "I wouldn't assume that the transformer is the same as that particular video has a UK plug on, it is possible it has a different transformer inside with dual windings, a 110V model might have a single winding transformer.Anyway, don't tit around with mains voltage if you don't know what you are doing! Also, I would suggest checking the output voltage on the transformer if it has another available winding.Just my thoughts."
},
{
"post_id": "",
"author": "katzohki",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 08, 2015, 10:06:57 pm",
"content": "Quote from: miguelvp on January 08, 2015, 06:31:15 amYou're right, but I prefer to discourage people from working on \"live\" mains voltage."
},
{
"post_id": "",
"author": "HomerA",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 22, 2015, 12:32:43 am",
"content": "Hi all,thanks for all the replies. I thought I would give you an update on how it went with the soldering iron. It turns out Helios was right. The transformer is a dual winding one. I did email Antex direct, just to check and there main man emailed me back to say that all there irons have dual windings . Here are a couple of photos of mine.I just pulled off the connector from the 110v and put it on the 230v and bingo all worked (had to change the plug to UK one first).Thanks for all the help. :-)"
},
{
"post_id": "",
"author": "katzohki",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 22, 2015, 03:23:22 pm",
"content": "Great!"
}
] |
2025-10-17T19:48:49.245272
| 19
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/110v-to-24v-transformer/
|
110V to 24V Transformer - Page 1
|
[
{
"post_id": "",
"author": "Izzy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 12, 2019, 02:24:57 pm",
"content": "Hello, I'm working on converting an electric wheelchair to a trailer moving dolly and the batteries in this thing are dead.Instead of paying hundreds for new batterles can I just use a 110V to 24V transformer?Does it have to be 24 AC or 24 DC.Can I use another type of power supply that puts out 24 volts?Thanks for your input!!"
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2019, 02:40:50 pm",
"content": "The transformer you mentioned is mains connected, is this what you want that the wheelchair is constantly plugged at the electricity wall outlet ?A.k.a. your wheelchair is wired, not good for mobility."
},
{
"post_id": "",
"author": "Izzy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 12, 2019, 02:43:06 pm",
"content": "Yes, I will want it plugged in!! Not concerned with having an extension cord run behind it!Also makes it a lot more compact!!!"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 12, 2019, 02:52:55 pm",
"content": "You need not a transformer but 24V SMPS (switch mode power supply). Transformer outputs AC but you need DC. Not to say even without rectifier, transformer will be larger, heavier and more expensive."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2019, 02:53:47 pm",
"content": "You certainly need DC, not AC. Fortunately 110VAC to 24V DC converters are widely available and aren't expensive.How many Amps does the motor draw? If you don't know, look at the nameplate on the motor and search the Internet for the part number, if it doesn't say.If it gives the power but not current, then it can be calculated using Ohm's law.You need a power supply which can deliver more current than the motor will use."
},
{
"post_id": "",
"author": "Izzy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 12, 2019, 03:55:49 pm",
"content": "Thanks Zero999, can you give me an example?Ok I think it's the draw is 64 peak and 13 continuous."
},
{
"post_id": "",
"author": "soldar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2019, 04:56:52 pm",
"content": "Some disjointed thoughts without proposing anything in particular.Electric cables around the floor are a trip hazard and an electric hazard.A motor will have a huge startup current compared to its continuous consumption. A battery can handle that pretty well but a power supply is going to have to be oversized.A DC motor would have high inductance and would not care much is the voltage is pure flat DC or pulsed in some way. You could probably use full wave rectified AC unfiltered. You could even use higher (mains) voltage with phase power control and full wave rectified. (Insert here all sorts of isolation, safety and security warnings.)"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2019, 09:03:49 pm",
"content": "Quote from: Izzy on January 12, 2019, 03:55:49 pm13A at 24V is no problem. The peak requirement is a little more tricky though. A 24V power supply capable of 63A is going to be expensive.How are you going to control the speed of the motor?"
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 13, 2019, 12:31:19 am",
"content": "Quote from: Zero999 on January 12, 2019, 09:03:49 pmCan capacitors help with this? (though they won't be small)"
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 13, 2019, 04:42:53 am",
"content": "Hi IzzyThere are a heap of mains to 24V power supplies here:https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20190112202104&SearchText=24V+power+supplyJust search through the suppliers lists. You should get a 24V 60A power supply for around $75 US delivered. Remember that if you want to, you can put one or more power supplies in parallel."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 13, 2019, 06:35:29 am",
"content": "Power supplies are dirt cheap. The power supply I use for some of my chargers for RC aircraft batteries supplies 24V at 54A and cost me $22. I used a pair of IBM server PSUs with a small modification to separate the DC ground from earth ground on one of them so they can be wired in series. I've been using it for years now, these are very commonly used by RC modelers. The power supplies are dirt cheap on the surplus market."
}
] |
2025-10-17T18:18:29.338390
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/110v-to-5v-module/
|
110V to 5V Module? - Page 1
|
[
{
"post_id": "",
"author": "metrologist",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 06, 2017, 02:24:27 am",
"content": "Time's up!I retrieved this module from a Brother MFP printer and I suspect it will take 110V AC on the white connector and output 5V. I started to draw a schematic but got lost. The transistors are marked 667 and show as 120V 1A npn transistors. Am I on the right track? If it is what I suspect I would use it to power a couple of small 5V fans in a power supply I'm building."
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2017, 05:51:14 am",
"content": "I see that board as a TDK high-voltage DC-AC inverter for CCFL backlighting. Not a 110VAC to 5VDC power supply.They take in 5 or 12VDC and output 900-1500VAC at several mA. Enough to give you a nasty shock.Probably a custom build for the printer display? TDK TAD376 has no search hits.http://www.mouser.com/catalog/catalogusd/645/2476.pdf"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2017, 08:26:10 am",
"content": "Yes, it looks like a CCFL inverter. Going from what you've already reverse engineered and the picture of the board, it looks like a Royer converter circuit.With regards to safety: the output frequency will be above 20kHz and will give you a burn more than a shock and the current will be limited to a non-lethal level."
},
{
"post_id": "",
"author": "metrologist",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 06, 2017, 12:04:34 pm",
"content": "Oh, well now I must find a use for it.I was working on the schematic a bit more and then went to feeding a signal from my sig gen at around 5V, I guess on the output side"
},
{
"post_id": "",
"author": "rsjsouza",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2017, 12:12:32 pm",
"content": "The previous comments are correct. One detail that detracts from your original assumption is that one of the poles of the white connector is directly tied to the negative output - if this was a mains power supply, one of the poles would be directly exposed to the low voltage section. Another giveaway is that the transformer construction is very inadequate for direct mains (50~60Hz) connection - usually at these frequencies the magnetic coupling requires a lot more wire and core material (and not ferrite as its core)."
},
{
"post_id": "",
"author": "Yansi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2017, 12:28:21 pm",
"content": "D667 = 2SD667http://www.redrok.com/NPN_2SD667_80V_1.0A_0.9W_Hfe160_TO-92MOD.pdf"
},
{
"post_id": "",
"author": "rsjsouza",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2017, 02:54:27 pm",
"content": "Quote from: metrologist on July 06, 2017, 12:04:34 pmWell, if anything, just be glad you did not use the module in the correct way with your oscilloscope plugged on the HV output - the oscilloscope wouldn't be happy with that."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2017, 03:26:02 pm",
"content": "Quote from: metrologist on July 06, 2017, 12:04:34 pmYou appear to have got the taps wrong. The centre tap should go to the positive supply, via the inductor and it's likely the transistors' bases are driven from a separate winding. Plenty of schematics can be found by entering Royer converter into a search engine."
},
{
"post_id": "",
"author": "metrologist",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "July 06, 2017, 06:39:37 pm",
"content": "I removed the images so as not to confuse someone in the future, since they are wrong."
},
{
"post_id": "",
"author": "stj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 06, 2017, 06:58:25 pm",
"content": "i just use usb chargers from discount stores.if your in the u.k. - poundland ones are good ( \"BigClive\" does teardowns on poundland stuff on utube)otherwise - inspect them before you trust them!!!!"
}
] |
2025-10-17T18:53:17.984714
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/110vac-to-240vac-smps-12v-5w/
|
110VAC to 240VAC SMPS 12V 5W - Page 1
|
[
{
"post_id": "",
"author": "rentner",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2013, 08:19:34 pm",
"content": "Is there a \"simple\" way, to get mains voltage down to 12V without using a 50/60hz transformer? I don't want to use anything, that can cause a bigger 50/60hz magnetic field, than just the traces of the PCB, because it can and will kill my project. I want to have a high density, so the required distance from a transformer to the rest of the PCB would be to big for me. 500mA to 1A is definitely enough. Very important: it definitely needs galvanic isolation from the mains. Not even 100MEG is acceptable. It needs to be isolated like air.I don't want to use a ready PSU, because DIY will give me a better look in how these small suckers work. I thought, I could just find an IC for that, but that did not happen.Well, well. What solutions do you offer? Or IS there actually an IC for that purpose, which will not cost too much?"
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 06, 2013, 08:40:47 pm",
"content": "I can't see how your going to do this job without a PSU or Battery source ? what is the project for it to be so sensitive to PSU noise.500 mA to 1 Amp is a demanding current for this project.SMPS is going to produce one hell of a lot of high frequency hash, along with the 50/60 Htz mains near the project input, if at high Z... and if a linear transformer is going to prove to be a magnetic field problem too; your going to either have a separate PSU DC cable feed off-board, or just battery powered on-off-board !At the end of the day, the engineering has to make it's compromise between wanted and what's feasible."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2013, 08:46:14 pm",
"content": "If you don't use a mains frequency transformer you will need a switching supply operating at a higher frequency and consequently a small high frequency transformer. Since higher frequencies tend to have more energy than low frequencies your interference problems may be worse. (Do you have problems with magnetic fields, electric fields, or electromagnetic radiation?)As far as isolation is concerned, a switching supply will have Y capacitors for safety, and those capacitors will couple the mains into your isolated side.I don't think you are going to get complete isolation without a large and expensive design, or a battery."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2013, 08:59:46 pm",
"content": "Low noise, direct mains input, compact size. Choose two.Quote from: rentner on May 06, 2013, 08:19:34 pmNot even 100 Meg? Why?"
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2013, 09:09:08 pm",
"content": "Quote from: IanB on May 06, 2013, 08:46:14 pm<nitpick> the capacitors are there to meet emission requirements. They are class Y for safety.</nitpick>"
},
{
"post_id": "",
"author": "rentner",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2013, 09:15:14 pm",
"content": "I know, that this definitely requires High frequency. In fact, the HF Magnetic field is not a problem at all, because 25khz or more is not audible. It is just for a small Amplifier. Anything below 20khz can cause the problem to be heared. That's the reason, why I don't want a 50/60khz transformer. For regulation i was thinking of simply an opto isolator."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2013, 09:18:19 pm",
"content": "Just audio? God, most \"audio people\" would have you excommunicated for ever suggesting putting an SMPS within twenty feet of an audio circuit! Just avoid having very high impedances (shield them if you must), ground properly and you'll be fine."
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2013, 09:33:44 pm",
"content": "A 50/60 Hz transformer is more than adequate for audio applications. The magnetic fields created by the transformer will not have any effect on a halfway decently designed audio amplifier. In case it is, you can use a toroidal or magnetically shielded transformer.An SMPS will almost certainly have worse performance in every respect, including 60 Hz hum. (from the PWM duty cycle variation, as well as the necessary class-Y caps). Also, it is a mistake to think that because the switching frequency is ~50+ kHz that it can't affect audio quality. While that frequency is not directly audible, high frequency interference can cause audio frequency artifacts. Try holding a GSM phone near a pair of cheap computer speakers sometime to see what I mean.The advantages of a SMPS is that it is smaller, lighter, more efficient, and cheaper (at mass production quantity) than a 60 Hz transformer. Low noise is not generally considered one of its virtues. It is possible to make a low noise SMPS if you need the cost/weight/size advantages, but if you are making a hobby project, start with a good linear supply.Finally, making a safe line operated isolated SMPS is not a good DIY project. If you do decide to go with a SMPS, buy an off-the-shelf supply and then add external filtering or post-regulation. You can get converters in a number of form factors including PCB plug-in modules that look like oversized ICs."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2013, 09:46:17 pm",
"content": "Quote from: ejeffrey on May 06, 2013, 09:09:08 pmOK, that makes sense."
},
{
"post_id": "",
"author": "NiHaoMike",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2013, 03:13:02 am",
"content": "Quote from: c4757p on May 06, 2013, 09:18:19 pmMy homemade Hybrid Digital amplifier is powered by an old laptop PSU and it works great. And a lot of newer (pure) digital amplifiers are using switching supplies to do the dynamic supply voltage."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2013, 04:03:51 am",
"content": "Oh, of course. I've done tubes (valves?) with a DC-DC before (two actually, one for the filaments!), all the while laughing with glee at how much it might piss off the old farts.Just saying that there is no reason to bother avoiding mains transformers, even the audio \"purists\" are OK with them."
}
] |
2025-10-17T20:22:38.277423
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/118-volts-each-outlet-combined-205-volts/
|
118 volts each outlet, combined 205 volts - Page 1
|
[
{
"post_id": "",
"author": "u666sa",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 09, 2025, 04:53:42 pm",
"content": "Trying to get 240 volts.Code:https://www.youtube.com/watch?v=64L4Pz4vuYcEach outlet measures 118 volts. When I combine two hots I'm getting 205 volts. What's happening?"
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 04:58:01 pm",
"content": "Quote from: u666sa on March 09, 2025, 04:53:42 pmAre you in a stand-alone house, commercial building or an apartment building?"
},
{
"post_id": "",
"author": "u666sa",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 09, 2025, 05:00:08 pm",
"content": "Quote from: bdunham7 on March 09, 2025, 04:58:01 pmI'm in appartment building in Florida"
},
{
"post_id": "",
"author": "Monkeh",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 05:02:04 pm",
"content": "Quote from: u666sa on March 09, 2025, 05:00:08 pmYou have two phases of a 120/208V 3-phase system, not two legs of a split single phase."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 05:04:04 pm",
"content": "2 phase 120 degrees apart,instead of a split/center tapped 120/240 v supply"
},
{
"post_id": "",
"author": "fzabkar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 05:12:37 pm",
"content": "118 x sqrt(3) = 204"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 05:54:19 pm",
"content": "As a visualization of three-phase power distribution, I consider three identical light bulbs, each connected from one line to neutral. Since there is no current in the neutral lead, it can be open-circuit with no change. This facilitates calculating the relationship between line current and power. The root-three results follow."
},
{
"post_id": "",
"author": "calzap",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 07:18:00 pm",
"content": "If you want 240 VAC, you’ll need a transformer unless there is an alternate source in the building. Even if there is, getting it to a specific apartment would probably take some persuading and expense.Mike"
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 08:19:00 pm",
"content": "I've encountered this only in commercial buildings and know it as a \"high leg delta\" connection. It's a bit confusing until you see how the distribution transformer is wired up.Usually the 208V is for bay lighting but here it must be air conditioning as a 3-phase load balanced somewhat in the overall building."
},
{
"post_id": "",
"author": "coppercone2",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 08:23:11 pm",
"content": "if you think thats confusing I found thishttps://www.researchgate.net/profile/Resmi-Reghu/publication/335126905/figure/fig1/AS:857327460696064@1581414203101/Star-delta-star-connection-in-SPW-APW.pngjust combine the two , and then add a tapI wonder if we will see hexagons eventuallyyou wake up, go to the circuit panel and see a faded schematic on the side of the box withhttps://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTw66lFJHA-MxxP2Pw25m_CbCIHkllMPoWh7A&sit means you are in the year 50000 A.D. . Your home also has a old rusty dedicated gas pipe for helium/oxygen/sulfur hexaflouride tri-mix."
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 08:27:42 pm",
"content": "Quote from: floobydust on March 09, 2025, 08:19:00 pmI've had that high-leg arrangement in a commercial building and it was that way because of 240VAC 3-phase loads (machinery) that wouldn't tolerate 208V. It could get really weird. The OP's situation is different. He is in an apartment building and in the 1960s-80s (IIRC--perhaps more) they would run 208VAC 3-phase WYE connections and provide 120V L-N connections off of that for individual units. 240VAC loads such as ovens would operate OK with 208VAC. There weren't necessarily any real 3-phase loads involved, this just reduced initial costs. Phase balancing was by random usage patterns. Neutral current issues were managed by less than capacity loads most of the time and I'm sure they hadn't even thought about them at that time since the big loads were light bulbs, electric ovens and wall air conditioners."
}
] |
2025-10-17T16:22:02.434026
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/118v-between-usb-shield-and-mains-earth-whats-happening/
|
118V between USB shield and mains earth. What's happening? - Page 1
|
[
{
"post_id": "",
"author": "aeberbach",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2020, 01:01:07 am",
"content": "Having watched Dave's \"EEVblog #279 - How NOT To Blow Up Your Oscilloscope!\" (because I did trip the RCD a few hours after getting a scope some years ago) I understand there's direct connection between scope shield and mains earth. What I did not expect was to feel a shock when touching the shield of the USB-type B plug at the same time as the oscilloscope shield clip. Measuring with a multimeter shows 118V AC between these two points...I'm using a FPGA development board that is programmed by USB but am not using the scope on it with USB connected. Instead I program it with a .pof file so that it will configure itself on boot from flash. I can program it, disconnect it from USB, and then power it from a bench power supply, red and black terminals only, no clip across to green so no earth connection. No problems there and safe scope probing. But in making the change, pulling wires out and reconnecting, I felt the voltage mentioned above.The USB lead is connected to an Anker USB hub powered by a 12V power adapter. The USB upstream is connected to a Dell monitor. That connects to two PCs - I use its KVM feature to switch between those machines and USB connections at the same time. If I take the hub and the monitor out of the equation and just connect the USB cable to the PC that does the programming I still see 88V AC between USB shield and scope shield.How does this happen? Do I have some electrical fault somewhere?"
},
{
"post_id": "",
"author": "aeberbach",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2020, 01:46:51 am",
"content": "I guess that means any device in the house could have the bad Y capacitor :-("
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2020, 02:40:10 am",
"content": "Quote from: aeberbach on November 11, 2020, 01:46:51 amno, it just means that your mains connector doesn't have Ground on the Ground terminal. Usually mains connector has a 3 terminals:N - neutral,P - phase,GND - grounding.In your case GND terminal is not connected and it leads to such issue."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2020, 02:44:01 am",
"content": "That's just the coupling thorugh the EMI suppression capacitor. Maximum current to fit within safety standards is something like 300uA. Classic web page on this subject:http://www.aplomb.nl/SMPS_leakage/Doc_ie.html"
},
{
"post_id": "",
"author": "Berni",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2020, 06:48:20 am",
"content": "Your earth connection is missing or interrupted somewhere. This can be a dangerous situation!This is leakage from mains filter capacitors in the PSU and this is normally diverted into earth so you don't get any voltage. But when earth is interrupted the voltage sticks around and since USB shields are connected to earth you also get this voltage appear on those.Often this voltage can be felt too if you touch it just right. But if you have multiple things plugged into a power strip with a missing earth the currents can add together from say the PC, 2 monitors, speakers etc... and then the current can actually become large enough to be unpleasant to touch. I seen it happen myself due to a faulty extension cord at a coworkers desk, also seen a youtuber reviewing a 3D printer get shocked by it after having multiple printers plugged into a similarly faulty extension cord (And blamed the 3d printer manufacturer until he found out what the problem actually was).Even when multiple devices combine there leakage currents on a common extension cord the currents are still too low to actually kill you, it just hurts a bit to touch. But if any of the devices fails and develops an internal short then live 230V might end up on this unconnected earth, this means that touching your computer case is the same as touching a live wire and that can definitely be FATAL!Get an electrician to look at it or at least get one of those power outlet testers with LEDs that show if the power socket is wired correctly and that earth works."
},
{
"post_id": "",
"author": "Nerull",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 11, 2020, 07:14:18 am",
"content": "Quote from: Berni on November 11, 2020, 06:48:20 amYou realize that a large percentage of modern electronic devices are double insulated and have no ground connection, right?This almost certainly includes the adapter powering the OPs USB hub."
},
{
"post_id": "",
"author": "Berni",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 11, 2020, 07:34:04 am",
"content": "Quote from: Nerull on November 11, 2020, 07:14:18 amYes a lot do not have ground, but desktop PCs and monitors pretty much always have IEC C13 mains connectors with earth in them. So if any of those are earthed the voltage should have went away once the hub is plugged in."
},
{
"post_id": "",
"author": "aeberbach",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 11, 2020, 07:32:33 pm",
"content": "Thanks all. I will need to unplug everything and check what appears to be grounded properly and what is not. I have two quite long power boards (Rack mount units repurposed) to check.I do see the voltage in two situations. One is when a desktop PC is connected via USB - 88V AC from USB shield to ground. The other is when the USB cable connects to an 8-port hub (powered by big laptop-style adapter, with earthed IEC cord) - 118V AC. That hub connects to the monitor's USB hub, the monitor connects the first mentioned PC and a Mac mini. All are powered off one long power board."
},
{
"post_id": "",
"author": "aeberbach",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 16, 2020, 01:52:54 am",
"content": "Disconnected and reconnected everything in the office one by one - it seems the problem was an 8-outlet power board where the brass earth contacts had become loose from many years of use. It was a Jackson unit, good quality, and so possible to open with a 2mm triangle security bit and repair. I didn't know they were still sold, maybe will buy more."
},
{
"post_id": "",
"author": "HackedFridgeMagnet",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 16, 2020, 02:51:56 am",
"content": "and I thought my -5V wrt ground was a problem."
},
{
"post_id": "",
"author": "Berni",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 16, 2020, 06:25:34 am",
"content": "Good thing you found it.Earth faults in extension cords are not all that rare. If the live or neutral breaks then the extension cord stops working and people stop using it (most people throwing it away) but if the earth connection breaks then the user does not even know it happened so they keep using it for years."
}
] |
2025-10-17T17:39:05.882468
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-0-12-500ma-transformer-enquiry/
|
12-0-12 500mA transformer enquiry - Page 1
|
[
{
"post_id": "",
"author": "vis5254",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 06, 2019, 06:33:48 pm",
"content": "This might be the silliest thing asked ever , but i just have a lack of clarity . ie , I've 12-0-12 500mA step down transformer. if I provide 12v ac voltage parallel to 10 ohm resistor , theoretically ohms suggest i would get 12/10 = 1.2A .. Do I ?? practically ??will my transformer current rating might affect this situation ?I was planning to generate 1 or 2 A ac current for current sensor testing !"
},
{
"post_id": "",
"author": "bob91343",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2019, 06:45:14 pm",
"content": "You would be overloading the transformer. It can deliver 12 Volts at a half ampere; any more load will take it beyond its ratings. You need a bigger one."
},
{
"post_id": "",
"author": "iMo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2019, 06:51:59 pm",
"content": "You will get 12Vrms with 24ohm resistor wired to 12V--0 terminals.You will get 24Vrms with 48ohm resistor wired to 12V--12V terminals."
}
] |
2025-10-17T18:11:29.746264
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-19v-strip-heater-for-bending-plastics/
|
12-19V strip heater for bending plastics - Page 1
|
[
{
"post_id": "",
"author": "slowpoke",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 15, 2021, 07:58:08 am",
"content": "I need an acrylic sheet bender. Checked out prices of the machinery and noped out real quick.Heatgun bending is not an option as pretty precise and neat bends are required.Can someone help me figure out how to go about making one ? I've seen some videos of people making them but usually all electrical bits explanation is missing.Ideally i need something that can strip heat a length of about 600mm, powered by 12V (ATX power supply?) or 19V (laptop power brick, beefier one, over 3 amps? ).How to go about calculating the nichrome wire i need, gauge and power requirements to achieve needed temps. Don't need the wire to glow white, just to keep to ~200-250 C. (I have some dead toaster heating element wire unwound somewhere in the parts bin...)Don't want to go full mains voltage (240V) for safety considerations.Anyone here constructed such a contraption ? Need input"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 15, 2021, 08:41:09 am",
"content": "I looked at making one ages ago and decided to go pay someone at the time to do it for meThere is plenty of videos on youtube including the one below but the key to it is control over the sheet when you have the bend area softened so some light clamping helps keep it nice. Also as per the video below the heat is controlled to a localized area by the channel which is fairly standard with the commercial units. Some Kapton or fiberglass tape to keep any bit of the acrylic away from the aluminium might be good too.Ball park 0.8-0.9mm Nichrome or Stainless Mig wire will be fine somewhere between 12 and 20V. A 12V car battery way back when used to be my go to for Foam cutting at 900-100omm typical temps are similar to what Acrylic needs to soften but the shorter run you will be close at 12V and 600mm with an extra 300-400mm run and an alligator clip to adjust the temperature. You should also be under 5A so even a decent bench supply will cope."
},
{
"post_id": "",
"author": "wizard69",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 15, 2021, 09:57:34 pm",
"content": "I haven't created a bender but at work we have a variety of heat seal tasks. What your want covering the metal is PTFE tape. The Tape is specially designed for such usage."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2021, 02:42:46 am",
"content": "Unlike the heatsealers the wire is below the surface of the table so you are better off without a cover for faster heat transfer to the acrylic. The bits that could do with some cover are the tops of the aluminium channel or just rebate them slightly below the surface like this should work. Hinges outside the 600mm for the OP and some sort of light clamp on the fixed surface to keep the sheet in place so the bend goes in the correct spot.Quick and dirty model herehttps://a360.co/3fAZhCr"
},
{
"post_id": "",
"author": "slowpoke",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2021, 10:28:46 am",
"content": "Mechanical part doesn't really bother me, i'm a makerIts the electrical part that i'm interested in.My question arises from the need to make a strip heater on zero budget. I do have some unknown wire from heating elements of toasters and hair blowers, i also want to power it from something less than mains, for safety concerns.I will dig out the heating wire today, just need to figure out how to measure/calculate/power it at length i need with atx(12v) or laptop(19v) power supplies."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2021, 10:44:55 am",
"content": "Hot and cold resistances vary a lot but a good way as you have 5V on the ATX start there with say 1m and take a current measurement. Your 600mm wide will soak up another 1-200mm getting off the surface then another 200mm as a slider resistance with an alligator clip to control it. You could add a buck convertor for control but the clip and extra wire is fine.With your 5V info on a metre will give you a better idea of Ohms/metre. Then all things being well pump it to the 12V side of it and check again on the metre. I suspect if your wire is in the 0.8-1mm range your Laptop supply will run out of current and be to much voltage. If it is say 0.4 you will be out of or close to out of voltage.\"Maker\" - CRINGE"
},
{
"post_id": "",
"author": "slowpoke",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2021, 10:55:05 am",
"content": "Quote from: beanflying on May 16, 2021, 10:44:55 amYeah, fairynuff, hate the word as well, but how else do you describe a \"cheap/broke diy'er\" ?(which i am).Checked out simple commercial strip heaters/benders out there, 1200 quid for 500mm one ? thanks but no thanks..."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2021, 10:58:31 am",
"content": "You'll have a devil of a job unwinding a used toaster element and getting the wire straight. The wire will be very brittle due to repeated cycling to bright red heat and oxidization. The hair drier element probably didn't get as hot, but will be wound in a small diameter coil so is likely to be equally hard to straighten. You *may* be able to use it still coiled if you support it with a tensioned glassfiber cord through it.Buying some 'virgin' Nichrome or stainless steel wire may well be your best option as you can then choose its diameter for a resistance per unit length appropriate for your desired heater power and supply voltage. You should be able to get a 'feel' for the max heater power required from the specifications of the commercial units you've been looking at.A 10A rated DC-DC buck converter module would give you a lot more flexibility so you can adjust the voltage for the temperature you require. Assume a 1800W hairdrier. At 240V its heating element draws 7.5A. You probably don't need to drive the element so hard so a 5A buck module may well be sufficient - you wont know till you extract the element, see how many parallel sections it has at full power and try powering a length of it to get a feel for the max current and voltage required. You probably need no more than 1/3 the current required to reach dull red heat. Don't expect a 'chinesium' buck module to deliver more than 1/2 of its nominal rating for long. 1/3 is a safer bet."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2021, 11:07:18 am",
"content": "Really simply the word 'Hobbyist' it is what I started out doing in Electronics 40'ish years ago. I have spent 30+ years as an Aeromodeler as a Hobby at least 'so far' it has avoid the 'maker' tag. The word 'maker' used by others toward me in particular professionally who saw it in print or on youtube and as I spent my four years at Uni I have a small issue with itRant over nowThe commercial units to take your ideas from are a rail at 90 degrees to the element and a stop/clamp to control distance from an edge to your bend. The Aluminum under the element surrounded by MDF will make a fairly good oven of sorts even at circa 100W. If you were doing production bends and needed speed then a second wire run otherwise less will be more and easier to control."
},
{
"post_id": "",
"author": "SmallCog",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 16, 2021, 11:33:09 am",
"content": "With the issues around electrical and plant safety we bought rather than made the acrylic bender at work.What I’ve learnt from it regarding making my own is that I won’t bother with the folding stuff, mine will just be a heated strip. I don’t tend to fold stuff in the machine at work I tend to do the folds outside of the machine (using jigs for repeatability)There are calculators like this you may find handy - double check the results I’m not vouching for ithttps://www.easycalculation.com/engineering/electrical/nichrome-wire-calculator.phpHere’s an Adam Savage video on strip heaters for anyone curioushttps://youtu.be/iHAkCYwxUb0"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2021, 11:42:49 am",
"content": "Good Calculator and seems about on the money for 0.8 or 0.9mm based on what I have done with it on foam cutting12V @ 5A for about 1m to 300+C.I had to run my own tests on some 0.2mm Titanium a week or so ago as all the vape crowd have little to zero idea and it varies a lot with Temp. Side note Kanthal is great too if you come across it for jobs like the OP's."
},
{
"post_id": "",
"author": "slowpoke",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 16, 2021, 11:50:30 am",
"content": "Bending out of the machine is a good advice and i was really planning on doing exactly that. I do have a large'ish laser cutter (900x600, 80W), been asked to do some bent acrylic stands and have no bender, hence checking what i can do on the cheap, as commercial heaters are stupid priced. If the job pans out and more orders roll in i might splash out for something fancy, but at the moment all my budget is going straight to materials for orders... (starting a business is a pain in the...well... there...)Make a flat strip heater (with aligning bits, no bending bits like hinges), laser cut all the jigs i need out of ply, bob's your uncle. Never did foam cutters although i do RC, multirotors and cars mostly though, no foam involved. And what little is it's cut on a laser."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2021, 11:57:58 am",
"content": "If you have someone around you who does Mig welding and in particular Stainless work go hit them up for a few metres of 0.9 Stainless wire. I brought a 500g spool years ago for hot wire jobs and it was well under $20. Nichrome is cheap too but getting it locally is generally a specialty element maker or evilbay and wait.I have all but the Tube assembled for a 1200x900 100W Laser build as my Toy one runs out of space way to often"
},
{
"post_id": "",
"author": "SmallCog",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 17, 2021, 05:39:21 am",
"content": "Laziness and having a bender at work have prevented me from making mine along with knowing that if I buy the materials I'll find them for free a few days later...My intention is to use 3 rectangles of timber (probably concreters form ply or melamine from old kitchen cabinets) and a length of aluminium U channel2 of the rectangles will be slightly smaller than half the size of the big one, the small rectangles will be attached to the big one (base piece) with the U channel between them.https://www.bunnings.com.au/metal-mate-20-x-20-x-1-5mm-1m-aluminium-channel_p1079323stretched across the U channel between some cup hooks will be my wire with a spring to keep it taught as it gets hot. U Channel will be slightly narrower than the with of the base board so the cup hooks can screw in.https://www.altronics.com.au/p/w0435-9m-nichrome-resistance-wire/I'll probably put a piece of right angle aluminium on it as a guide... If I haven't started work on 20 more things I've seen on youtube by then!"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2021, 06:21:12 am",
"content": "I don't like the cup hooks and croc clips approach. Use the U channel as the ground return for the hot wire, so both connections can be to one end of it for convenience. Then its simply a matter of bending up a tab at the far end to hold the spring, crimping the wire to the spring or using a single bare terminal from a terminal block to join them, and fitting a small ceramic two way terminal block at the near end, screwed to the base of the U (or on a bent-up tab) with one side cut to form a tab to go into one way for the ground connection."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2021, 07:38:58 am",
"content": "What you like or don't about Crocodile clips and screws they work and have being for decades on model Aircraft Foam bows as a simply low tech adjustable resistor. Going back into that time a 5A variable power supply was a complete luxury item and not the sub $20 hunks of junk from China we have available now. These days I would just pull out my 0-15V 60A Manson and get to cooking. For the OP sounded like they didn't have a variable supply or to many spare $ so croc clips makes sense.As to using the aluminium as a return has some good and a bad points. The worst one is if you tweak the wire physically wired as you suggest you can place a near dead short from wire to channel a lot easier this will get you molten Nichrome going sprong in a random direction due to the spring tension. Yep you can cover all that up or make guides close to the channel but to much complexity for a simple home made bender maybeHaving a bit more look at the heat up time as youtube decided I needed to watch more videos about this I would be tempted to do two runs of 0.8-0.9 wire for about 10A @ 12V in the channel as toward 60 seconds seems to be the heat up time for thicker Acrylic."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2021, 07:56:47 am",
"content": "Yes a short to the channel would be bad if the PSU wasn't current limited (or fused) below the fusing current of the resistance wire. In that case, a separate fully insulated ground return would be a lot safer, leaving the channel floating."
},
{
"post_id": "",
"author": "slowpoke",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 17, 2021, 10:48:06 am",
"content": "Yes, i don't have variable psu. Should have, but dont. But have plenty of ATX power supplies in the box to use. Checked some of them out yesterday, 12V 20A rails on the 250W psu's.I do have 15mm aluminium U channel kicking about, will be using opposite ends for powering and route the wiring neatly underneath.Can't find the damn wire though. House moves suck, it takes time to organise your \"order\" of things (aka organised chaos).I must disclose that i never bent acrylic in this way. Heatguns usually, but bends come out too sloppy that way."
},
{
"post_id": "",
"author": "SmallCog",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 17, 2021, 11:45:59 am",
"content": "Once you’ve got the nack it’s great to work withI’m thinking of grabbing a set of the hair straightener looking benders for doing smaller brackets and stuff, eg:https://www.ebay.com.au/itm/Acrylic-Shape-Bender-Right-Angle-Bender-Bending-Electric-Iron-Tool-Kit-Hot-Sale-/224450681913?_trksid=p2349624.m46890.l49286] https://www.ebay.com.au/itm/Acrylic-Shape-Bender-Right-Angle-Bender-Bending-Electric-Iron-Tool-Kit-Hot-Sale-/224450681913?_trksid=p2349624.m46890.l49286"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2021, 11:53:28 am",
"content": "There is a few Indian or Pakistani (forgotten now) Youtube acrylic sign making channels I watched ages ago. Absolute magic skills making side walls on raised lettering dealing with long lengths of floppy plastic.Decided I am off to Bunnings tomorrow as I need to go to town and get some 12x1.5mm channel and I have the 18mm MDF already in the shack along with the Nichrome or Kanthal when I work out what works best at 600mm'ish."
},
{
"post_id": "",
"author": "slowpoke",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 17, 2021, 07:22:24 pm",
"content": "I want to try this:...but for that i need to upgrade my Z axis drive from dumb AC lift motor to stepper+driver. Would save me some headache with benders:D"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 18, 2021, 07:45:49 am",
"content": "Interesting idea using out of focus energy to do the job. Lots of playing and funny shapes made along the way I suspectWent to the hardware shop and grabbed some extra bits and pieces for a build. Few things not shown on the model screws, bolts etc. Laser cut 6mm Angle bracket on the left with a stop block fitted into the slot for easy repeat angles. Working on a maximum bend distance of 450mm and screwing the lot to a 600mm wide bit of MDF so it stays put.Model is still here if anyone wants to pinch dimensions off ithttps://a360.co/3fAZhCr"
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 18, 2021, 08:06:20 am",
"content": "Here's a place in the U.K. to get NiCr wire up to 3.25 mm .wires.co.uk. They have other wire as well. I got some Manganin some time ago for sense resistors."
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 19, 2021, 05:06:42 am",
"content": "Quote from: wizard69 on May 15, 2021, 09:57:34 pmIs that the same plumbers thread sealing white tape? Is that heat resistant?"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2021, 05:15:40 am",
"content": "Quote from: Vincenzo on May 19, 2021, 05:06:42 amNope not Teflon Tape for plumbing it is a Teflon encapsulated Fabric (likely fiberglass). Shot is of the jaw area of my double sided floor model sealer."
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 19, 2021, 05:30:56 am",
"content": "Quote from: Ian.M on May 16, 2021, 10:58:31 amGreat advice. Slowpoke is trying to jump from 1200 quid to zero. To avoid the cost of a converter, an atx power supply with the jungle of wires with each one of the output voltages tied together (or even cleaner, desoldered from the board and single thicker wires soldered instead), especially the 12V. Both the 5V and the 12V in all of them should have more than 10A. Trial and error with the length and current. Nichrome small reels are very budget friendly for some gauges that are commonly used in other applications. How about a timer (to turn it off after an experimentally measured adequate ON time) with a short sound beep for the operator to bend?"
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 19, 2021, 06:12:15 am",
"content": "Is high temperature (shiny red wire, pushing it to the limit) fast application better for acrylic or slow lower temp/amps?or is there a sweet spot somewhere. I have never done heat bending before."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2021, 06:34:03 am",
"content": "In order to generate heat you need resistance in the wire and a current to pass. P = I2RSo the problem becomes with coated copper is it has a very very low resistance so to generate a set power you need a much larger current so it makes a very poor element. Nichrome is circa 100 times more resistive than Copper for example (varies with heat/purity and lots of other things). Physical melting of the wire when it is dissipating the power is also an issue. Several other options can be used including Kanthal, Stainless Steel (NiChrome alloy in most cases), Titanium and more.So if you feed the 5A figure and the Temperatures needed (300C) and feed it into the Calculator from earlier for say a 500mm length of 20AWG (0,8mm) NiChrome I was throwing aroundhttps://www.easycalculation.com/engineering/electrical/nichrome-wire-calculator.phpyou get some nice easy numbers of around 5V @ 5A or 25W. This is not a lot of power to heat in particular the thicker Acrylic so I am planning on two runs for about 50W over the 500mm and with a bit of a fudge I can fit three wires safely into the 12mm channel for 75W."
},
{
"post_id": "",
"author": "SmallCog",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 19, 2021, 07:47:24 am",
"content": "Quote from: Vincenzo on May 19, 2021, 06:12:15 amDon’t want to be too hot, you need the top side to be pliable/bendy before the bottom side gets burntMy commercially made bender takes about 100 seconds to get 3mm acrylic just right for bending"
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 20, 2021, 12:53:54 am",
"content": "Quote from: SmallCog on May 19, 2021, 07:47:24 amThank you, sir. Great numbers to experiment with to get to the \"sweet point\" with some voltage/current converter."
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 20, 2021, 04:35:05 am",
"content": "Acrylic will bend easily at 160C ."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 20, 2021, 04:47:41 am",
"content": "Part of the non science bit is heating it through to that yield point on the far side as quick as you can without cooking it on the close side."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 21, 2021, 06:28:10 am",
"content": "Flushed out my current stash of heavier Resistance wires. 18AWG (0.9 measured so more like 19AWG) I will use Nichrome as it is what I have most of and TempCo doesn't matter at all. The Kanthal is the same diameter but harder to come by so I will save it.First very crude test on 500mm of it 5V got to 4.4A on my bench supply. With a simple bead contact thermocouple I only hit 130C so more volts and amps need to get to the Acrylic yield point.Breaking out some more muscle and heavier leads on my messy bench for more testing. Current on the Manson reads high but I will make a better rig and re run it with a calibrated shunt and properly terminated wires. The Croc clips I have with 4mm ends are getting warm at the 8A so not a good indicator.Voltage is correct as checked on a DMM.5V 130C7v 180C8V @ circa 7A (fudged for the reading) 230CLooks like for the OP 12V on a 650mm'ish run will pull somewhere in the 250C+ range at 8A'ish so you should be fine (pending some more testing) with the PC supply and 18AWG Nichrome.Playing with my newish Thermal Camera too the results might be a little questionable due to the surface emissivity of the wire. Still learningSeems like the calculator earlier is fine for electrical Calculations but off for Thermals too"
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 21, 2021, 09:25:25 am",
"content": "https://www.ebay.com/itm/202945759465?hash=item2f408288e9%3Ag%3AYVgAAOSwfD1eexYC&LH_BIN=1This is an amazing cheap little board that gives you constant temperature better than sensing indirectly through current. It comes with default hysteresis of 2 degrees C, but you can lower that. I use them in all cheap fan-less space heaters after replacing the little relay that they come with with a little bigger one and adding a tiny $1 12v 500mA SMPS power sypply from ebay.I once made these instructions graph for using their three button setup"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 21, 2021, 09:41:15 am",
"content": "Temperature range isn't up to the 2-300C unfortunately. 300C is sort of in the area of K type thermocouples only and would be pushing RTD's and a lot of other sensors to get one that would cope.I do have a pair of these fitted to some Fridges on my Mobile Coffee making bench as the built in controls were a bit rough on the fridges to keep the Health mob happy and stop the milk from freezing so it is a good board"
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 22, 2021, 04:39:33 am",
"content": "are you talking about the little cylindrical \"sensor\" that comes with those, that it has an upper temperature limit it can withstand before it is damaged that is less than what is needed for this application?"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 22, 2021, 04:52:25 am",
"content": "I have never looked at the sensor for ratings as I am running at 3-4C. Also I have never tried to program them to the top limit and I suspect you will find the board will likely be firmware limited to that 110C?"
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 22, 2021, 07:10:04 am",
"content": "where does the 110 number come from?and I still don't get where the limitation is. I only imagined that the little sensor and it's wire will not do 300 degrees, but to the microcontroller, they are all numbers.I see those who convert a toaster oven use a little heavier duty sensor that is sometimes threaded"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 22, 2021, 07:46:27 am",
"content": "Read the evilbay add you postedI would think this to be correct and mine are packed away in a container so I cant check. If you have one of your try winding it above 110C."
},
{
"post_id": "",
"author": "Vincenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 22, 2021, 06:12:20 pm",
"content": "\"evilbay\"quite interestingand kind of accurateI just saw the range they posted on evilbay, sorry about asking.But still, don't see why the sensor can be replaced with a more robust industrial kind of thing with same characteristics"
},
{
"post_id": "",
"author": "Marco",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 22, 2021, 06:36:01 pm",
"content": "Quote from: beanflying on May 17, 2021, 07:38:58 amWith undoubtedly some pretty bad burns along the way ... it doesn't matter whether you know those clips could be hot as hell, use it enough and it's going to slip your mind eventually and you're going to adjust them at the wrong time."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 24, 2021, 04:29:20 am",
"content": "Yep Beers and having mates 'help' you make foam wing cores, the odd ouchy has happened over the years. These days I am spoiled for choice with adjustable power supplies so it is a non issue, it is just a quick and dirty option for those without like the OP.Started my build I guess too. I had some 6mm Acrylic on the Laser so I cut the Angle bracket out and a test pattern in card to make a Template stack to route most of the hinge rebate to aid my average woodworking skills."
}
] |
2025-10-17T17:28:01.504366
| 42
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-220v-50hz-power-inverter/
|
12-220V 50Hz Power Inverter - Page 1
|
[
{
"post_id": "",
"author": "johnnyblaz",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 12, 2017, 09:30:08 pm",
"content": "Hi there. I was going through this inverter circuit and I couldn't fully understand the circuit. As far as i figured out the CD4047 is used to generate the 50Hz PWM/square wave signal and the transformer is used to step up the voltage to 220V but what is the purpose of the LM324 ICs and 2N3055 & C1061 transistors? Any help would be appreciated. Thanks"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2017, 12:30:44 pm",
"content": "That is a very poor design.The LM324 is being used to buffer the output of the clock generator while providing current limiting. 2N3055, C1061, and then a pair of paralleled 2N3055s are configured as a three stage darlington transistor to get enough current gain.Problems with this circuit include high dropout of the triple darlington configuration causing excessive heating and low efficiency, overlap of the output clock causing excessive shoot-through current, and poor current sharing of the paralleled output transistors."
},
{
"post_id": "",
"author": "johnnyblaz",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 13, 2017, 02:39:21 pm",
"content": "I really appreciate your help.Any suggestions on how to improve this design?Please include component/ic number for the new design."
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2017, 05:32:04 pm",
"content": "Get an EG0002 board and a couple fet and you are done for a couple bucks and you have sine wave."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 13, 2017, 06:13:25 pm",
"content": "That looks like it would have been a reasonable design for the 1980s, but these days inverters all use a high frequency DC-DC section followed by a chopper or PWM sine generator, it's a lot more efficient."
},
{
"post_id": "",
"author": "Audioguru",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 14, 2017, 01:11:04 am",
"content": "Does anybody make or use a squarewave inverter anymore?The circuit shown was a 500W squarewave inverter atwww.electyronics-lab.comand it s original horrible design did not work. The circuit you found also does not work because the R and C for the CD4047 are wrong.I corrected the RC on the CD4047 and made a few more improvements about 13 years ago and many of these simple inverters were made and used. The circuit was built with common cheap parts in the Philippines and used by poor people who had no electricity. A battery boy picked up the discharged 12V batteries and replaced them with charged ones every few days."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 14, 2017, 03:14:59 am",
"content": "Most of the inexpensive inverters now produce a \"modified sine wave\" which is really just a square wave with some dead time inserted. The better ones put out a true sine wave but those are still relatively expensive compared to the common modified sine type."
}
] |
2025-10-17T18:58:49.360760
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-channel-dac-sample-and-hold-design/
|
12 Channel DAC sample and hold design - Page 1
|
[
{
"post_id": "",
"author": "vixo",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 20, 2020, 10:13:28 am",
"content": "I like to design musical equipment and often in these designs parameters are voltage controlled. I'm trying to design a circuit which will store the voltages from 12 pots and store them digitally for recall. Digitising seems fairly straightforward, but when the voltages are recalled they need to \"hold\" at the DAC outputs. What is the preferred way of doing this - are there DACs which incorporate sample and hold circuits, or should I use a single channel DAC and switch it into a twelve channel sample and hold (does such a thing exist)?Ive been looking at the MAX11311 for the DAC - it has 12 channels, 12 bits and is fast enough for my needs, however it seems complicated and I'm not sure whether the analogue conversion will hold at each channel outputcan anyone give me some tips / pointers?"
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2020, 11:01:03 am",
"content": "Unless you're really trying hard to cost-optimize, and with trivial accuracy/stability/linearity etc. requirements, I would probably just throw DACs at this problem. Something like the MCP4728 is 4x12 bit DACs for $2 at qty 1. Put three of those on your board on the same I2C bus and it'll be pretty easy to control too. DACs for control purposes like this almost never require a continuous clock and data, just send them values when you feel like it and they will hold them.Maybe doing 12 channels of S&H (a capacitor, analog switch, and opamp) would be a bit cheaper, but it'd also require a lot more 'active engineering' and tuning to get right."
},
{
"post_id": "",
"author": "vixo",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 20, 2020, 11:09:56 am",
"content": "Greeat, thanks! i was just looking at that solution. Just to make sure - i don't need a chip select pin on those DACs and can just control all on the same i2c bus?"
},
{
"post_id": "",
"author": "splin",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 20, 2020, 02:49:32 pm",
"content": "Quote from: ve7xen on February 20, 2020, 11:01:03 amIf they fit your needs great, but be aware they're pretty meh. Dave Jones fell foul of that in his PSU (#240), in particular the untrimmed gain error of up to 1.5% and up to 20mV offset. Max INL (integral linearity) is +/- 13 LSBs which means it only has the accuracy of an 8 bit DAC. The internal reference has a temp coefficient of 45ppm/C which may be good enough but it is very noisy - 0.1 to 10Hz noise is dreadful at 290uVpp! The DAC's noise is not specified.If you need better, TI do a few; the DAC60501/2/4/8 (1 to 8 DACs) in particular look very good for the price. INL max is 1 LSB, LF noise is only 14uVpp and the reference TC is 10ppm max (it was 5ppm in earlier revisions of the datasheet). Untrimmed gain and offset errors are also much better.AD/Linear Technology have a large selection of DACs with up to 8 channels but they are rather expensive."
},
{
"post_id": "",
"author": "Jeroen3",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2020, 03:20:27 pm",
"content": "Why use DAC's when you can use 12 PWM outputs? Or is that not audiophoolery enough?If they emulate potentiometers they don't need fast changes, so slow filters is not a problem right?12 ADC channels and 12 PWM channels can probably be found in one cheap STM32 part."
},
{
"post_id": "",
"author": "vixo",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 20, 2020, 04:13:52 pm",
"content": "Quote from: splin on February 20, 2020, 02:49:32 pmah that's most probably a deal breaker for me, thanks for pointing it out. I've never used a DAC before, how realistic is mV accuracy?Quote from: Jeroen3 on February 20, 2020, 03:20:27 pmpossibly, I want to generate accurate DC voltages. The voltages are CV voltages for pitch, to which the ear is very sensitive and I'm working in microtones rather than ordinary 12 note tuning - im not exactly sure how accurate I need them to be - but my first guess would be mV accurate (if this is possible/realistic). How accurate can I get a PWM at DC?"
},
{
"post_id": "",
"author": "schmitt trigger",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2020, 04:27:53 pm",
"content": "You surely are aware that for a PWM to DC conversion there will be ripple.Of course you can reduce the ripple by using the highest possible frequency and then a higher order low pass filter with a crossover frequency at least a couple of orders of magnitude lower....you would have to calculate/simulate how much ripple would be left, and the effect it would have in your 12 bit-equivalent requirement.Perhaps it is a non issue, but something that requires inspection.A continuous-time higher order filter would require a lot of components, though."
},
{
"post_id": "",
"author": "jesuscf",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 20, 2020, 05:04:17 pm",
"content": "Quote from: vixo on February 20, 2020, 10:13:28 amI don't quite understand how this will operate. Suppose a pot gives a voltage of say 3.14V, then the n-bit integer representation of 3.14V is obtained with the n-bit ADC and immediately put in the m-bit DAC as 3.14V? Then if the 'store' button is pressed, the DAC value is saved in memory. Now the pot voltage changes to 2.72V and the DAC outputs 2.72V, but shortly after, the 'recall' button is pressed, and the m-bit DAC output is now 3.14V? If that is the case wouldn't be better to use quadrature encoders instead of pots to adjust the DAC outputs directly?"
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2020, 08:52:18 pm",
"content": "Quote from: vixo on February 20, 2020, 11:09:56 amIf you read the datasheet you'll see that you can program the address in EEPROM by I2C and using the ~LDAC pin provided for this purpose. Otherwise they will all respond at address 000. So you can either program them out of circuit with some kind of test jig, and not connect the ~LDAC pin, or you can connect the ~LDAC pin to your controller and program them that way, and then address them on the same bus by the addresses you programmed.QuoteGood point, I wasn't making a suggestion on that part, just that they're available and cheap! Good to know that it's a pretty horrible device, but I guess you can't complain at the price."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2020, 01:15:17 am",
"content": "Tektronix did that for their early microprocessor controlled oscilloscopes. The potentiometer values were immediately digitized and then regenerated with a DAC with the microprocessor in the middle. ADCs and DACs were expensive back then so both were multiplexed. For the DAC, a multiplexer was used to connect it iteratively to a series of hold capacitors followed by JFET operational amplifiers configured as voltage followers.So a DAC, 4051 multiplexer, and two TL074 quad operational amplifiers yield 8 output channels. But today quad DACs are available at reasonable prices.Keep in mind that potentiometer \"settablity\" is only just better than 8 bits and 10 bits is more than enough. But this is a good match for common 12 bit converters because they are usually only linear to 10 bits anyway. If you are hoping to get 12 bits, 1 part in 4096, out of single turn potentiometers, then you will be disappointed; they are just not that good."
},
{
"post_id": "",
"author": "jesuscf",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 21, 2020, 04:32:29 am",
"content": "Quote from: David Hess on February 21, 2020, 01:15:17 amMore recent Tektronix oscilloscopes use encoders, which to me makes a lot more sense:https://www.eevblog.com/forum/repair/tek-tds3000b-front-panel-encoders-are-these-custom-made/"
},
{
"post_id": "",
"author": "vixo",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 21, 2020, 08:58:33 am",
"content": "Quote from: jesuscf on February 20, 2020, 05:04:17 pmNormally, the voltage comes from the pot, when the recall button gets pressed, the voltage comes from the DAC. Quadrature encoders? I don't think so - the resolution has to be fine enough that you don't hear 'jumps' in the pitch and also coarse enough that scrolling them doesn't take too long - normal pots work well for this. Plus I can get pots cheap, the right size and I don't like the feel of encoders.Quote from: schmitt trigger on February 20, 2020, 04:27:53 pmYeah, I was thinking that I could extensively filter that out enough for it to be useful. I think the DAC is a better betQuote from: David Hess on February 21, 2020, 01:15:17 amThat is what I considered first of all, what kind of hold capacitors were used? I know of an arrangement like this (https://www.electronicshub.org/sample-and-hold-circuit/) but it doesn't seem like it would hold a voltage for a long timeThat's interesting that it's only about 8 bits in resolution. However, the purpose the of digitising and recalling the state is to match the voltage on the pot as closely as possible. Maybe a less accurate ADC would be ok, I'm not sure yet - I have to hear it in action to say whether I'm happy with it"
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2020, 10:07:32 am",
"content": "Low parts count method: 3x MCP4728 (as someone pointed out)Lowest parts cost: 12x PWM (can be done as with 4 muxes and 3 PWMs and some passives, with 0-25% range)If you are doing POT>MICROCONTROLLER>DAC all the time, then linearity is not a big issue in reality, if you are doing substitution (switching from POT wiper to DAC), then you might need something better than MCP4728."
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2020, 11:36:39 pm",
"content": "Quote from: vixo on February 21, 2020, 08:58:33 amYou should be able to estimate the current out of the capacitor in very rough terms by looking at the chosen opamp's input bias current, capacitor leakage, and any leakage path back through the switch/mux. Once you have that, you can estimate the voltage change per time for a given value/type of capacitor, and use that to select an appropriate value / timing. Since I assume you'd still have a DAC sourcing the voltage into the S&H, you shouldn't need to hold the value for very long (10s of ms at most?) before you can refresh it. Low leakage type capacitors would normally be used here, probably a film or NP0 type in your case.Edit: Example...not careful engineering here but to put some numbers on it...TL074 has input bias current max of 7nA over the full temperature range.A poly film cap should have leakage under 10nA4051 off-state leakage current max is 100nA (!!)So we expect leakage current < 117nA.Capacitor voltage change with a constant current discharge is given by $$\\frac{1}{C}It$$ where C is capacitance, I is the discharge current, t is time in seconds.So say you have a 470nF film capacitor, after 10ms your voltage will have changed about 2.5mV worst case."
},
{
"post_id": "",
"author": "Ground_Loop",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 22, 2020, 03:30:49 am",
"content": "I have a MIDI to CV controller that does just what you’re asking for on seven output channels by sequentially feeding the DAC (12 bit) output to charge capacitors on the input to FET op amp voltage followers. It scans them fast enough that the charge loss is imperceptible between scans. I’ve also done something similar to sample white noise for a true random sample and hold function."
},
{
"post_id": "",
"author": "jesuscf",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 22, 2020, 07:03:42 am",
"content": "Quote from: vixo on February 21, 2020, 08:58:33 amWith incremental quadrature encoders arbitrary resolution can be achieved. Also the amount of change can be adjusted programmatically depending on the speed of the rotation. As for the feeling, there are quadrature encoders that 'click' and quadrature encoders that are smooth."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 28, 2020, 09:20:57 pm",
"content": "Quote from: jesuscf on February 21, 2020, 04:32:29 amEncoders were not common back then and would have been more expensive. Their late 22xx series and 24xx series oscilloscopes also used dual potentiometers rotated out of phase on a single shaft as continuous encoders which worked very well. If necessary, a potentiometer used as an encoder can also provide absolute positioning.Based on the performance and reliability of the common mechanical encoders found on many products now, I think potentiometers are usually better. What I do not understand is why nobody makes small quadrature optical encoders like those found in mice."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 28, 2020, 09:48:03 pm",
"content": "Quote from: vixo on February 21, 2020, 08:58:33 amTektronix used 0.1 microfarad polyester film capacitors. If we assume 10 bits (1000 counts) and 5 volts, then 5 millivolt resolution and 1 nanoamp of leakage would require updating every half second so not particularly demanding. Doing significantly better requires some care in circuit layout and the environment to prevent excessive leakage on the surface of the printed circuit board.At high temperatures, a better capacitor like polypropylene is required and CMOS or low input bias current bipolar (1) amplifiers do better than most JFET parts. A different multiplexer than the cheap 4051 might be required.(1) The input bias current of a bipolar input operational amplifier actually tends to decrease at high temperatures so low input bias current bipolar parts may even be preferred. I used to use the LM11, sort of an improved LM308 low input bias current operational amplifier, for sample and hold circuits which had to operate at high temperature. Today there are CMOS input parts which are almost as good like the LMC6081 series."
},
{
"post_id": "",
"author": "jesuscf",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 29, 2020, 08:05:00 pm",
"content": "Quote from: David Hess on February 28, 2020, 09:20:57 pmThey do! For example:https://www.bourns.com/docs/Product-Datasheets/em14.pdfQuadrature optical encoders are very nice but also very expensive."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 02, 2020, 06:44:22 pm",
"content": "Quote from: jesuscf on February 29, 2020, 08:05:00 pmThe ones used in mice are much less expensive because they are not as integrated; only the emitter and detectors are required."
}
] |
2025-10-17T17:54:41.197209
| 20
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-gt-12-buck-converter-design/
|
+12 -> -12 buck converter design? - Page 1
|
[
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 29, 2014, 11:18:37 pm",
"content": "I've been using DC-DC converter modules on my Hydra boards, but I've decided to see if I can save a couple bucks (see what I did there?) by making my own buck converters. I was able to design one for +12->+5 @ .5A without too much difficulty, but I'm not finding a lot out there that will make -12 @ 50 mA from +12 (or +5 for that matter). The designs I have seen have easily twice as many components as the +12->+5 that I've got queued up, and they make me give second thoughts to replacing the bipolar DC-DC and just going from 2 down to 1 instead of removing them altogether."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 11:28:14 pm",
"content": "MC34063 ? (edit : just search digikey/mouser/farnell/newark for 34063, or 33063 or 3063 as in az34063, ncp3064, ncp3063 etc etc it's made by lots of companies)Freeware calculator:http://sourceforge.net/projects/mc34063uc/Online calculators (less complex) :http://www.nomad.ee/micros/mc34063a/"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 30, 2014, 02:15:05 pm",
"content": "Hey, thanks to you both - between the two of you, I was able to see section 5 of this document:http://www.ti.com/lit/an/slva252b/slva252b.pdf,which looks like just what the doctor ordered."
},
{
"post_id": "",
"author": "rob77",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 30, 2014, 02:30:01 pm",
"content": "couldn't agree more. the mc34063 is a versatile (buck,boost,inverting) and CHEAP. it's avilable in DIP and SMT (actually it's dirty cheap here ~25 cents for SMT and <50cent for DIP). you can build a DC converter under 2-3Euro using it."
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 30, 2014, 05:13:53 pm",
"content": "I've got one more question. I think I may have an answer, but want to make sure I'm right.http://www.st.com/web/en/resource/technical/document/datasheet/CD00001232.pdfFigure 17 looks like nearly *exactly* what I want.I could drive it from my +5 rail, but that rail is generated by another dc-dc converter from +12. Cutting out the middle-man would seem to be a good idea.But what are the implications of raising Vin on that sample circuit from +5 to +12 volts?Looking at the math just below, it *appears* that I would need to raise the value of L1 from 90 µH to, oh, I dunno, maybe something closer to 150 µH. Other than that, the resulting chip-apparent Vcc of 24 volts is in spec, and provided the correct voltage specs are kept for the caps... am I missing anything crucial?"
},
{
"post_id": "",
"author": "krivx",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 30, 2014, 05:26:33 pm",
"content": "Another option if you need inversion and not a huge amount of current is a charge-pump inverter. You can avoid using inductors, you usually just need two external capacitors which are specified in the datasheet. Linear have a few nice ones, you might need to shop around if you need a very cheap solution:http://www.linear.com/product/LTC3261http://www.linear.com/product/LTC3260"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 30, 2014, 05:34:57 pm",
"content": "The LTC3261lookslike a great solution, but it's a dollar more costly than the DC-DC converter I'm already using."
},
{
"post_id": "",
"author": "krivx",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 30, 2014, 06:31:56 pm",
"content": "Quote from: nsayer on May 30, 2014, 05:34:57 pmMicrochip do some cheaper partshttp://www.digikey.com/product-detail/en/TC962COE/TC962COE-ND/418719"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 30, 2014, 08:25:36 pm",
"content": "Quote from: nsayer on May 30, 2014, 05:13:53 pmI watched the video and found that there were a couple of formulae missing from the ST data sheet (for individually figuring out Ton and Toff). On Semi's is much better (http://www.onsemi.com/pub_link/Collateral/MC34063A-D.PDF).I've decided to make both the +5 and -12 supplies using this chip.For the +12 -> -12 @ 50mA, I got Rsc=2.4?, Ct=200pF, L=470µH and Co=68µF.For the +12 -> +5 @ 500mA, I got Rsc=0.16?, Ct=200pF, L=15µH and Co=68µF. I must make sure the diode will handle 2A peak current.(some of those part values are rounded to the most convenient nearby)Of all of the parts, it appears that the 0.16? resistor is the fiddliest one. Why that can't just be a jumper is beyond me. I mean, I found one at DigiKey, but it's an order of magnitude more expensive than the other 0805 resistors I buy."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 30, 2014, 08:52:30 pm",
"content": "Use that calculator I linked to in a previous post.Here's some examples:Vin = 11-13v , Vout = 5v +/- 0.1v @ 500mA , Rsc = 0.27 , Lmin = 38.5 uH 1A , Ct = 330pF, diode 1n5819 , Cout = 330uF 0.081 ohm esr or better (pretty much anything low esr 330uF 10v or better should do it)Vin = 11-13v , Vout = -12v +/- 0.1v @ 200mA , Rsc = 0.27 , Lmin = 87uH 1A , Ct = 330pF diode 1n5819 , Cout = 150uF 0.11 ohm esr or better0.27 ohm is relatively standard size, if not you can get two 0.56 ohm and put them in parallel, or get 3 1ohm resistors and put them in parallel (it will be close enough).The inductor values are the minimum, use standard values... 39uH, 47uH, 68uH, 100uH ... if you get better price buying in volume and size isn't an issue, get 3 x 47uH , use two in series for the -12v to get that 87uH. Make sure the ones you get have a peak current of 1A or better and lowThe capacitance is the minimum to get a low ripple, you can use more capacitance without any problems. you don't save money going with the lowest 68uF capacitor (hence why i chose two standard values, 330uF and 150uF)"
},
{
"post_id": "",
"author": "rob77",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 30, 2014, 09:09:46 pm",
"content": "that calculator is nice, i was not aware of it's existence until you pasted the imagesi'm using the mc34063 every time i need to make small power DC converter, but i was always kind off \"eyeball-ing\" the initial values and then adjusting them based on measurements"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 31, 2014, 04:59:22 pm",
"content": "In case anyone's interested, here's the final (?) outcome. The 34063 is now doing all of the DC-DC conversions necessary at a cost savings of close to $6 (in unit quantities)!"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 31, 2014, 05:52:16 pm",
"content": "I'd be interested to see a picture with just the top layer and one with just the bottom one... or a schematic.It doesn't look so well layed out to me, especially that ground trace going all around the board.. and do you have to place the ISP header so far away from the atmega and use vias to route those wires?"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 31, 2014, 06:32:19 pm",
"content": "Quote from: mariush on May 31, 2014, 05:52:16 pmThe schematic was attached.QuoteThere's actually a ground plane on both sides that isn't displayed. The thick traces are either the +12 or +5 rail, depending on which one.QuoteYes. There is a 2x16 LCD module that dominates the other side of the board. The connectors (including ISP) mount on the \"bottom\" along with the LCD, and so must be placed out of the way. That part of the design is fairly well proven. And, of course, programming happens only very, very occasionally, and in isolation with all of the rest of the functionality of the board.I'll attach a picture of the finished device. The board isn't the exact same variant, but you'll get the idea."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2014, 05:37:37 am",
"content": "LTM8045, my newish goto inverting/buck regulator. Piece of cake to use as long as you have a BGA adapter board"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2014, 07:05:51 am",
"content": "Quote from: Skimask on June 01, 2014, 05:37:37 amGoodness! That's a tremendously expensive part, isn't it?"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 02, 2014, 12:51:29 am",
"content": "Something just suddenly occurred to me and has me a bit concerned.The resistor between Vcc and SEN, OVR and SWE is going to take Ipk amount of current, isn't it? For the 500 mA 12->5 converter, that's an amp.Um.That's alot, isn't it?P=I^2*R... That's going to have to be a 1/3 watt resistor, no?"
},
{
"post_id": "",
"author": "nsayer",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 21, 2014, 02:43:20 pm",
"content": "The boards arrived, and it all works! The +5 supply shows around 40 mV of ripple and the -12 supply shows something like maybe 100 MICROvolts of ripple! I don't know for sure how much the 5 volt current is, but the 12 volt current for the whole board is just under 50 mA.I'm quite satisfied for my first try!"
}
] |
2025-10-17T20:00:17.876391
| 18
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-hours-urgent!-video-rca-to-vga-schematic-needed/
|
12 Hours Urgent! - Video RCA to VGA Schematic Needed - Page 1
|
[
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "October 21, 2011, 10:43:34 am",
"content": "i have a task tommorow (12 hours and counting) that i have to shoot/record an event and show live on LCD projector. my video cam only has that yellow rca out for TV, but the projector in the hall has VGA input. is there any simple and quick wiring on how to output my video cam (rca) to the projector (vga)? hope to get answer within 4 hours so i'll have 4 hours soldering and another 4 hours sleeping. please help."
},
{
"post_id": "",
"author": "deephaven",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 21, 2011, 11:05:40 am",
"content": "You can't do it by simple wiring, it is a completely different standard and you would need a video to VGA converter box. Are you sure the projector doesn't have any other inputs besides VGA?"
},
{
"post_id": "",
"author": "amspire",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 21, 2011, 11:13:34 am",
"content": "You need to get a TV tuner card for a Windows PC with a composite video input. Probably worth something like $30-$40, but retail may be double.The as long as the PC has VGA output, you can take the composite (RCA) in and output it to the VGA screen.In a pinch, you can do the same thing with the USB video capture dongles worth about $20, but really, USB is not quite fast enough. You may find yourself stuffing around trying to get the right compression working.Richard"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 21, 2011, 11:18:36 am",
"content": "Almost all projectors have an RCA video input.There may be an issue though if the projector is mounted high up on the roof out of reach and they have only cabled the VGA connector down to the floor."
},
{
"post_id": "",
"author": "Joshua",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 21, 2011, 12:44:59 pm",
"content": "What kind of storage does your camera use? If its flash memory than just copy it to a computer (borrow a laptop?) and use that. If it used DVD storage, use Handbrake software to 'rip' the DVD to computer.If it uses DVDs, you will probably have to format it in the camera before using the software.Let me know if you need more details.Joshua"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "October 21, 2011, 03:34:53 pm",
"content": "ok. times up. deephaven seems to conclude it in clearest manner, there's no direct way. i guess 2 wires rca -> 15 pins vga is impossible without extra components (chip?). i googled i saw vga->rca is possible, but i guess not the other way around. the projector is high above as Psi predicted, few tens feet overhead, the wire goes inside the ceiling and popped out another tens feet away to the back of hall, vga only. @Joshua: thats not an option, this is a \"live\" show, storage is even not mandatory. i guess i'll go as amspire's suggested, that is my backup plan, ie rca->usb convertor->netbook->vga. i have the device. but it kinda inefficient, its like going round the longer road to go to your neighboor house just next to you. thanks everybody for suggestions, i'll go setting up my netbook and video convertor tonight to bring tomorrow."
},
{
"post_id": "",
"author": "deephaven",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 21, 2011, 03:56:08 pm",
"content": "This is the sort of thing you need:http://www.amazon.co.uk/ClimaxDigital-Video-S-Video-Converter-Compatible/dp/B001AUFVYE/ref=pd_cp_ce_2"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "October 21, 2011, 04:19:57 pm",
"content": "yes, if i can have the schematic."
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 21, 2011, 05:03:47 pm",
"content": "My guess is that it uses something likethis. How's the schematic going to help you?"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "October 21, 2011, 08:12:01 pm",
"content": "looking at your linked picture, well its not going to help. btw, my netbook is set, not up to the desired performance fps, maybe due to multiple conversion and software rendering, but thats the best i can cramp this few hours. gtg sleep, 2 hours left"
},
{
"post_id": "",
"author": "NiHaoMike",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2011, 04:11:13 am",
"content": "Quote from: amspire on October 21, 2011, 11:13:34 amUSB 2.0 is more than fast enough for digitized composite video.If it's a newer camera, it likely would have IEEE1394 and/or USB. Then it's just a matter of using xawtv, mplayer, or similar to play back the stream."
},
{
"post_id": "",
"author": "amspire",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2011, 04:26:02 am",
"content": "Quote from: NiHaoMike on October 23, 2011, 04:11:13 amI was talking about using the standard cheap USB video capture dongle to capture the composite video. Converting from Composite Video was the original requirement.USB2.0 cannot maintain the video framerate uncompressed, so you have to use the built in MPEG2 compression in the dongle. It works, but is low quality.Yes, if the signal is being compressed in the camera, then USB2.0 would be adequate without any dongle.Richard"
},
{
"post_id": "",
"author": "NiHaoMike",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2011, 05:07:51 am",
"content": "Composite video only has a 6MHz bandwidth. That's only 96Mbps after 8 bit digitization, while USB 2.0 does up to 480Mbps. (Account for blanking and the actual data rate is even less.)"
},
{
"post_id": "",
"author": "amspire",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2011, 05:41:19 am",
"content": "You are right, but USB is not great at maintaining the full rate - particularly coming from a $20 dongle. It might manage 15 frames a second.Firewire was always much better at streaming, but the new USB3 will be fine."
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "October 23, 2011, 08:19:50 am",
"content": "my video cam has firewire (ieee1394) and can transfer the video realtime to my PC, but the netbook doesnt have the port, so the usb. and yes that was cheapo dongle i was using. and all video capture devices i have (all categorized as cheapo though) are sucks at transferring vidz through USB, i got the feeling i will blame on the usb connection, or more like the software capturing it. the way i see it, 720 x 480 x (3bytes/pixel) x 30fps = ~30MB/sec uncompressed. taking mpg let say 1/10 compression size = 3MB/s, still a big figure from practical point of view. greater compression achiveable but that should take a real hardware converter i guess, and that not taking into account the efficiency for the driver/OS/API/software when the data is actually arrived inside the CPU. btw, the event is over, maybe one time i will look into the RCA->VGA device suggested by deephaven above, or more robust USB video capture device.edit: and i'm a strong believer that 480Mbps (60MB/s) is purely theoritical, from my day to day experience using USB connection transferring large data."
}
] |
2025-10-17T20:38:02.699537
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-pin-micro-connector/
|
12-pin micro connector - Page 1
|
[
{
"post_id": "",
"author": "scthom560",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 09, 2025, 12:29:25 pm",
"content": "Hi All.Do you recognize the connector type shown in the photos.I have searched online, used Google lens but not had much luck.I'd really appreciate your help, need it for a project I'm working on.Thanks, Tom."
},
{
"post_id": "",
"author": "squadchannel",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 09, 2025, 12:41:25 pm",
"content": "JST GH"
},
{
"post_id": "",
"author": "scthom560",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 09, 2025, 02:45:20 pm",
"content": "Thank you!!!"
}
] |
2025-10-17T16:22:03.237217
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-v-car-voltage-stabiliser/
|
12 V car voltage stabiliser - Page 1
|
[
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 20, 2014, 05:12:08 pm",
"content": "Hi, was looking for different 12V car voltage stabilizers, DIY circutry etc. I found this cheap ready to use one from ebay/china wth a so called XL6009I need something like that for input from a car battery and output for a picopsu for a car computer.anybody any experience? well... ordered 2 pieces, will test it and see.http://www.ebay.com/sch/i.html?_odkw=XL6009&LH_BIN=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313&_nkw=XL6009&_sacat=0"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 20, 2014, 05:42:08 pm",
"content": "no experience, basically you want a buck/boost converter. I'm going to guess the chip they are based on is one of those and in fact if you read the data sheet you will probably find that it's example circuit is the same as the circuit you are buying."
},
{
"post_id": "",
"author": "gxti",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 20, 2014, 05:50:26 pm",
"content": "A boost converter like the ones you linked is only going to be able to increase the voltage, not decrease it. Your car is going to be putting out 14 or more volts most of the time as that is the charge voltage for the battery. The regulator you bought will not decrease that to 12V. Buck-boost or SEPIC is what you want. Or if you're cheap you can get a step-down (buck) module, set your boost module to put out 20V, and feed that into the step-down module to get the 12V you need :-)You probably already bought the picopsu, but they do have an automotive version that is designed for this exact use."
},
{
"post_id": "",
"author": "Richard Crowley",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 20, 2014, 06:07:45 pm",
"content": "Yes, as @gxti says, you are in that akward region where your picoPSU wants \"regulated 12V\", but your vehicle supply could range from 10V to 16V (at extremes). So you need something specifically designed to handle the \"hostile\" vehicle power environment. Been there, done that, not worth \"hacking it\" when the proper solution is available."
},
{
"post_id": "",
"author": "Richard Crowley",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 20, 2014, 06:49:26 pm",
"content": "Without knowing what kind of battery you are asking about, nobody can help you.Different battery chemistries require different charging regimes.What does \"12V DC to 24V battery charger\" mean?Does that mean you want to charge different batteries that range from 12V to 24V?Does that mean that you want to charge 24V batteries from 12VDC power source?"
}
] |
2025-10-17T20:03:58.736801
| 5
|
electronics
|
beginners
| false
|
https://www.eevblog.com/forum/beginners/12-vac-dimmer/
|
12 VAC dimmer - Page 1
|
[
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 12, 2020, 04:30:22 am",
"content": "I would like to control the brightness of some 12 VAC outdoor lights.What kind of solutions do you recommend? An off-the-shelf solution would be great.Would a dimmer module designed for mains powered incandescent bulbs work?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2020, 11:18:42 am",
"content": "What sort of lights are they? LED, halogen/incandescent?If they're incandescent/halogen, a dimmable electronic transformer and a phase controlled TRIAC dimmer can be used to dim them. Note that halogen lamps can suffer from a reduced lifespan, when dimmed.https://sound-au.com/lamps/elect-trans.html"
},
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 13, 2020, 04:19:33 pm",
"content": "Thanks for the info.They are LED lights.There are a bunch of hobbyist triac modules available which can be controlled by a microcontroller (and they have the zero-crossing signal so you can implement the proper phase control), but I was wondering if there was something commercially available or if one designed for mains power would work or could be modified to work for lower voltages.:https://robotdyn.com/ac-light-dimmer-module-1-channel-3-3v-5v-logic-ac-50-60hz-220v-110v.html"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2020, 04:29:12 pm",
"content": "Quote from: ledtester on June 12, 2020, 04:30:22 amPhase control dimmers require the high mains voltage to trigger properly and will not work on 12 VAC. They should work on the mains voltage side of the 12 VAC transformer with some limitations when powering a transformer.A variac (autotransformer) would work but power will be limited to the wiper current limit."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2020, 04:40:50 pm",
"content": "Quote from: David Hess on June 13, 2020, 04:29:12 pmThat will work for incandescent lamps, but not most LEDs, as they will probably have a built-in constant current source."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2020, 04:50:09 pm",
"content": "Analog mains voltage phase control TRIAC dimmers typically have a DIAC in series with the gate to get a sharp 'snap action' trigger pulse, and a well defined threshold so that as the RC delay network charges the phase at the triggering point is stable. The breakover voltage of the DIAC is likely to be greater than 17V, and if so it will never trigger on 12V AC. If its under 17V, even if you mod the RC network to charge much more rapidly, it will only have a very narrow control range around 50% power + off, as it can only trigger when the instantaneous AC voltage is over the DIAC breakover voltage.However a digital dimmer that drives the TRIAC from a MCU, may be modifiable to work with low voltage AC.If not intended for a transformer load, TRIAC phase angle dimmers may well develop an asymmetric output waveform at certain power settings leading to DC imbalance, and saturation of the transformer core, resulting in grossly excessive current and damage to the dimmer and/or the transformer. Two wire dimmers that are simply wired in series with the load are more likely to be problematic than three wire dimmers with line in, load and neutral connections.Also note that LED lights intended for AC input may well not be suitable for dimming.If they were suitable for PWM dimming, you could probably do something with a pair of beefy back-to-back MOSFETs with a 555 PWM circuit driving their gates. The gate drive PWM circuit would require a floating DC supply referenced to the MOSFET sources, which would be easiest to do with a bridge rectifier feeding a reservoir cap and a wide input range isolated DC-DC converter. Don't forget a heavy duty RC snubber across the MOSFETs to damp the back-EMF from the transformer secondary leakage inductance and the wiring stray inductance."
}
] |
2025-10-17T17:48:12.982830
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-volt-12-amp-hour-battery-replacement/
|
12 VOLT 12 AMP HOUR BATTERY REPLACEMENT - Page 1
|
[
{
"post_id": "",
"author": "magnetman12003",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 02, 2017, 07:21:31 pm",
"content": "I wish to replace a 12 volt 12 amp hour battery with a AC TO 12 volt DC power pack. This power pack must light up 9 seven watt 12 volt LED bulbs and NOT '' PULSE'' light them. I already have power units that do just that for some strange reason. What do I look for on Ebay that will do the job and equal what the battery can put out?"
},
{
"post_id": "",
"author": "suicidaleggroll",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2017, 07:24:41 pm",
"content": "You want a 12V supply that can do at least 63W (5.25A). Since this is eBay, you should be looking for a 12V supply that's rated to at least 300W (25A) to account for gross negligence in design and marketing (somewhat tongue-in-cheek, but not really)."
},
{
"post_id": "",
"author": "sokoloff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2017, 07:29:46 pm",
"content": "In addition to what @suicidaleggroll said, I'd put a multimeter (set to amps) in series with your existing install to understand what the true current draw is. Many \"7W LEDs\" only draw 3W or so, because of offsetting gross negligence in marketing of LEDs...Figure out what the amp draw is, multiply it by 1.5 and buy a 12V supply of at least that size.If you don't want to go to that trouble (or don't own a meter or don't know how to measure current), buy a 12V, 100W or greater supply. Note that if this is for indoors, a PC power supply is likely to support that. If it's for outdoors, a landscape lighting transformer (one that outputs DC) is likely to meet that spec and be designed to run for hours on end with that type of load."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 02, 2017, 07:51:11 pm",
"content": "Another option would be to replace the lamps and most likely the holders and wiring (presumably the insulation won't be enough for 120VAC) with mains lamps.If you tried the LEDs on a power supply and they pulsed on and off, it's most likely because the power supply was shutting down, because the current was too high. If you don't want to or it's impractical to replace the lamp, holders and wring, then you need a 100W 12V power supply, as mentioned above. A quick Google search reveals many possibilities."
},
{
"post_id": "",
"author": "magnetman12003",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 02, 2017, 08:52:33 pm",
"content": "Thanks fellows,I found a 100 watt unit12 volt unit."
}
] |
2025-10-17T18:57:24.502215
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-volt-scooter-hack/
|
12 Volt scooter hack. - Page 1
|
[
{
"post_id": "",
"author": "davelectronic",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "December 23, 2016, 08:55:14 pm",
"content": "My Son picked up a freebie scooter in a building. After testing the control pcb is toast. Not wanting to throw £££ at it i was thinking a simple relay to momentary switch hack. As the inital current and start is likley to be huge, i was looking for a soft start idea if possible. Its not worth me throwing pounds at it, but the motor spins up with 12 Volts applied. The SLA is 7 Ah i can't find a rating on the motor, but its been reduced down with gearing. Any ideas to a soft start with a high current relay and momentary switch would be great. Thanks, any ideas appreciated."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 24, 2016, 10:01:48 am",
"content": "If you're looking for something really quick and dirty (as in your button and relay) then a high power series resistor is the old-time DC motor starter solution. That would limit the stall current but have less effect as motor speed increases and current drops. If you took 1 Ohm as a starting point then that would limit motor current to 12A. Whether you go up or down from there depends on the motor size, mass you're moving, jerkiness etc.It's not elegant, or battery efficient, you need a chunky resistor - it would disipate 140W stalled (less in practice with the thing running). Watch the burn risk! Also not very efficient in battery terms. Got any old wirewound heating elements etc?Your other alternative might be to look on ebay or somewhere for a MOSFET PWM DC motor controller. You probably want to be looking in the 30A range.Edit: Maybe something like this:http://www.ebay.co.uk/itm/1500W-DC-12V-50V-PWM-30A-DC-Motor-Adjust-Speed-Controller-Potentiometer-TE565-/142081401882?hash=item2114b6241a:g:wsYAAOSw6n5Xq2b7I see 10A ones too, but that might be cutting it close, not knowing the motor. Should be an easy job to move the pot external - presumably there's already some sort of hand control in place."
},
{
"post_id": "",
"author": "orolo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 24, 2016, 10:18:38 am",
"content": "You could try modifying a soft-start circuit for audio amplifiers,like this from the excellent Rod Elliot's site,dispensing with the transformer, rectifier and high voltage protection, which would simplify things a lot. The basic idea is setting up a timer which acts upon one relay: normally closed to some power resistors in series with the load, and normally open to a short to the load. The timer keeps the relay closed for a fixed time, the switches to full loading."
},
{
"post_id": "",
"author": "taustin",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "December 27, 2016, 07:38:17 pm",
"content": "I know this is a bit more than you were thinking, but it might not be too hard to put together a PWM controller.A POT, microcontroller, and a couple of FETs can do the trick. Sure, there is a little more to it than just that, but once you understand it all it isn't too bad. If you wanted to skip the POT you could simply have the microcotnroller ramp up the duty cycle to help limit starting current spikes.Good luck with whatever you figure out."
}
] |
2025-10-17T19:06:07.396290
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12-volt-soldering-irons/
|
12 volt soldering irons - Page 1
|
[
{
"post_id": "",
"author": "dtRCasa",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 07, 2015, 10:26:53 pm",
"content": "It would be good to power a soldering iron from the car batterywhile working on the car, but Weller wants an astonishing $125.90for a 12 volt soldering iron, No. TCP12P. Seems excessive, whycan't i just connect the battery to a $5.00 iron?"
},
{
"post_id": "",
"author": "kingofkya",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 10:30:50 pm",
"content": "Ohms law....The heater is just a big resistor."
},
{
"post_id": "",
"author": "Howardlong",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 10:42:48 pm",
"content": "I bought a 12V iron from Radio Shack several years ago, ISTR it was about $20 or so.Alternatively, how about an inverter, or a gas iron?"
},
{
"post_id": "",
"author": "kingofkya",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 10:53:13 pm",
"content": "Yeah you can get cheap ones because you dont care how clean the power is.http://www.amazon.com/Coleman-PMP200XL-Cup-Style-Power-Inverter/dp/B0006GQA8E/ref=sr_1_6?ie=UTF8&qid=1420671147&sr=8-6&keywords=Coleman+inverter"
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 11:02:35 pm",
"content": "You can get on eBay unregulated DC irons, some are just typical 936 handles direct wired...and there are proper drivers for various handles which can take a DC voltage down to 12v, add your own handle..."
},
{
"post_id": "",
"author": "theoldwizard1",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 07, 2015, 11:20:04 pm",
"content": "Quote from: dtRCasa on January 07, 2015, 10:26:53 pmI have one of those Weller irons and it is really very nice ! 40W but the temperature is controlled by a standard WellerCurie temperaturetip."
},
{
"post_id": "",
"author": "Wilksey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2015, 12:17:20 am",
"content": "I have a Weller gas powered one, and I must say, it works quite well for working on cars etc."
},
{
"post_id": "",
"author": "dan.soethe",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "January 08, 2015, 07:20:30 pm",
"content": "I have a butane powered one, I use it all the time when there's no power near by."
},
{
"post_id": "",
"author": "W8LV",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 09, 2015, 08:01:29 am",
"content": "Butane, but you have to really be careful around all of the carpet and vinyl so that you start one Hell of a car fire."
},
{
"post_id": "",
"author": "W8LV",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 09, 2015, 08:02:27 am",
"content": "....so that you DON'T start a car fire... ;"
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2015, 01:42:30 pm",
"content": "12V on a 24V/50W iron will not produce 25W, it will be 12.5W..."
},
{
"post_id": "",
"author": "macboy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2015, 03:10:05 pm",
"content": "A standard soldering iron doesn't use much power, how about using a small inverter with a 120 V soldering iron?Or try a butane soldering iron. I have one and I really like it. I pulled it out the other day when I needed to do a small job just a few feet away from the bench, instead of using a basic iron. The biggest issue with these is controlling the temperature manually."
}
] |
2025-10-17T19:49:31.641383
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120-amp-max-welder-needs-only-a-20amp-breaker/
|
120 amp max welder needs only a 20amp breaker - Page 1
|
[
{
"post_id": "",
"author": "mikeinfodoc",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 04, 2017, 04:15:54 pm",
"content": "I have a 90amp flux core welder which works on standard US 115V mains.It says it uses 120amps max/peak, yet the manual says it only needs a 20amp breaker (as a min)Can someone explain to me how a 120peak amp welder needs only a 20amp breaker?I assume it may be cap's inside which handle the shorter amp pulses...I am probably wrong. I welcome feedback"
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 04:22:07 pm",
"content": "Well, 20A times 120V is pretty much the same as 100A times 24V. So, they do it by reducing the voltage at the arc.There are limits to how low the arc voltage can get and still be a viable welder but it must work because these MIG machines are all over the place.My old 240A stick welder needs a 50A 240V circuit (IIRC)."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 05:59:07 pm",
"content": "Put another way: Power = Volts × Amps.A 20A breaker on 115V. Power = 20 × 115 = 2300W.As stated above, the output of the welder is a much lower voltage, so the current can be much greater for the same power level.The reverse will be true inside your car's ignition system: a few Amps at 12V in, milliamps at 12kV out."
},
{
"post_id": "",
"author": "CaptainNomihodai",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 06:33:00 pm",
"content": "Quote from: mikeinfodoc on April 04, 2017, 04:15:54 pmI'm fairly certain pulsed mode is exclusive to high-end TIG machines... Anyway, I'm curious as to how well a 115V powered wire-feed welder actually works. I had a 115V cheap Chinese inverter-based stick machine and it was crap. It worked, but it was very difficult to use (I am not a skilled welder) compared to an American 240V machine.I would be skeptical of that 120A figure, since the power factor of the machine is probably quite low (assuming it's a transformer machine).Quote from: rstofer on April 04, 2017, 04:22:07 pmThat's what the manual says it needs, or that's what it actually uses? My ~30 year old Dialarc 250 says it needs something ridiculous like a 150A breaker (for the non-PFC version, which I have)... I have yet to trip the 60A breaker that I run it off of."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 06:33:26 pm",
"content": "There is also the matter of peak power. My air compressor has a LRA of something like 60A, but it will plug into a 15A circuit. It draws a very brief surge when the motor first starts up, but it is short enough that it does not trip the breaker. Circuit breakers can carry surge currents substantially higher than their steady state holding current."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 07:16:42 pm",
"content": "My 120A welder has a rating plate of needing 26A at full 120A welding current, but you only use that kind of current with a 6mm welding rod ( quarter inch in the USA) to weld a pair of 30mm steel plates together, and if you are doing that at all regular then you need a bigger welder in any case. Open circuit voltage is around 70VAC, but drops to around 10VAC when you have an arc struck, so running it off a standard 16A socket is fine. Typically I use it around 60A or so, with 2.5mm rods, and there it is fine.Of course, now I have an inverter welder I use it instead most of the time, much better weld, much better starting and I can actually weld thin plate with it, instead of having an impromptu plasma cutter that uses a welding rod. But yes, the welder transformer puts the power from the wall output into a very small spot, so can do some serious heating on metal."
},
{
"post_id": "",
"author": "johansen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 08:25:31 pm",
"content": "20 amp breakers need 30 amps to trip at 50% duty cycle."
},
{
"post_id": "",
"author": "Paul Moir",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 08:47:23 pm",
"content": "It's unlikely you'll find a capacitor in there. Usually it's transformer, rectifier and choke. The transformer does the 20A->120A transformation, hence the name. The rectifer gets you DC and the choke is used for smoothing. If it was just a capacitor, as soon as the wire made contact all the energy stored in the capacitor would get dumped into the stickout and blow the wire to bits."
},
{
"post_id": "",
"author": "langwadt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2017, 09:18:19 pm",
"content": "Quote from: Paul Moir on April 04, 2017, 08:47:23 pmMIG usually have capacitors as well they use ~constant voltage, stick and TIG is constant current"
},
{
"post_id": "",
"author": "Paul Moir",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 12:38:41 am",
"content": "Ah yes, my cheapy 90/130 doesn't but I see people \"upgrade\" them by adding some. Better ones appear to have some capacitance as part of their design."
},
{
"post_id": "",
"author": "cs.dk",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 05, 2017, 03:32:12 am",
"content": "Quote from: SeanB on April 04, 2017, 07:16:42 pmA 6 mm rod won't even light at such low amperes. Typical figures (depends on rod though), 2,5 mm 60-110A, 3,2 mm 70-150, 4 mm 150-240A.(Sorry for OT)"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 04:35:21 am",
"content": "Quote from: Paul Moir on April 04, 2017, 08:47:23 pmEveryproperMig I've had anything to do with has had capacitance on the secondary and plenty of it, my single phase 180 A has 80,000 uF.Without capacitance you need additional inductance to smooth mains frequency otherwise Migs create too much splatter. The only exception I've seen is a 3 phase Mig, the frequency of the rectified secondary being 3x that of single phase.Inverter type welders is where the future is, so much grunt for their size and weight not to mention better efficiency."
},
{
"post_id": "",
"author": "Paul Moir",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 06:12:44 am",
"content": "Oh I agree completely about the inverters.Note that this is a flux core welder we're talking about here so it's likely a low end one. In fact, I'll stand by what I said about it being likely there's no capacitor.But that's obscuring the point that capacitance after the rectifier does make sense, and I certainly was wrong in spirit as I was thinking that MIGs generally don't have them."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 07:28:08 am",
"content": "Quote from: Paul Moir on April 05, 2017, 06:12:44 amNot necessarily.A Fitter/Boilermaker I knowonlyuses gasless flux cored Mig wire in his 3 phase Mig, along with CO2for the nicest finished Mig welds you ever did see.Sure this sort of defeats the main advantage of using Mig, that is no post weld cleanup but they sure did look classy.A buddy has a fairly new Strata inverter Mig, a single phase unit and the welds that thing makes are pretty nice too but not as good as the old fella that uses gasless wire and CO2."
},
{
"post_id": "",
"author": "gnif",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 05, 2017, 07:37:04 am",
"content": "I have a lovely old adjustable AC CigWeld arc welder I inherited from my dad, its just a huge transformer on wheels. I would like to have a play with DC welding, would a heavy enough (200A) bridge rectifier stand up to this kind of abuse/use? Obviously would need to be sufficiently cooled. The welder's maximum output is 160A, but I have never measured it's voltage (and wont until the rain outside stops)"
},
{
"post_id": "",
"author": "langwadt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 07:45:38 am",
"content": "Quote from: tautech on April 05, 2017, 07:28:08 amI think the main advantage of MIG in that case is productivity and quality, long continues welds are faster and doesn't risk inclusions from starts with a new stick every so often"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 07:46:49 am",
"content": "Quote from: gnif on April 05, 2017, 07:37:04 amIf you mean using it as a Mig supply, no.Mig uses variable voltage while stick arc welding uses variable current."
},
{
"post_id": "",
"author": "langwadt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 07:46:57 am",
"content": "Quote from: gnif on April 05, 2017, 07:37:04 ama number of big rectifiers in parallel with enough wire resistance to sorta balance current between them could work"
},
{
"post_id": "",
"author": "gnif",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "April 05, 2017, 07:49:56 am",
"content": "Quote from: tautech on April 05, 2017, 07:46:49 amNo, not MIG, just stick arc welding, it is variable current."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 07:50:45 am",
"content": "Quote from: langwadt on April 05, 2017, 07:45:38 amQuite true for the inexperienced welder.One other advantage of Mig (for steel) is the welds are high tensile....try a fillet weld with stick and Mig, then try to break them and you'll see which is the stronger."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 07:56:46 am",
"content": "Quote from: gnif on April 05, 2017, 07:49:56 amNot so successful for an old style single phase welder, the rectified secondary frequency is a little too low for smooth DC welding. In 3 phase machines they form a bridge with hory big stud diodes.Inverter type welder outputs are high frequency by nature and only a rectifying stage is then required."
},
{
"post_id": "",
"author": "Paul Moir",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 08:08:56 am",
"content": "I think the major advantage with MIG vs fluxcore* is that you don't have crap shooting everywhere and fumes shooting up your nose!Fortunately I now live in TIG land almost exclusively, where I don't have to be fast nor do I have all that junk flying about. It's the classical music of welding.While I'm sure your pressure welder is doing it right for what he's doing, on thin metal fluxcore* is a real pain.* fluxcore without gas."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 08:17:19 am",
"content": "Quote from: Paul Moir on April 05, 2017, 08:08:56 amThere's another:Try using ordinary Mig outside on other than the calmest of days.Yep, you need a suite of tools to meet your needs, just like in electronics.400 A arc, 180 A Mig, 150 A Tig/stick and an Oxy set do most anything I need."
},
{
"post_id": "",
"author": "Vtile",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 08:28:49 am",
"content": "There is more than just \"higher frequency\" the 3-phases do interlap. Because of this the six-pulse DC (fully rectified three phase AC) looks roughly with the scope like a 1-phase pulsed DC that is smoothed out with bad capacitors.Put these three functions in your preferred graphing calculator or even Excel. First phase does not come with rectification, it is broken.1: SIN(x)2: SQRT((SIN(x+(PI/3)))^2)2: SQRT((SIN(x+(2PI/3)))^2)Quote from: tautech on April 05, 2017, 04:35:21 am"
},
{
"post_id": "",
"author": "mjrandle",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 08:57:07 am",
"content": "The welder will have a limited duty cycle at maximum welding current of 120 A, e.g. 20-30% every 10 min, to ensure average input current does not exceed 20 A. The thermal overload control shuts down the welder and effectively sets the duty cycle. The allowable weld current will be greatly reduced at 100% duty cycle, could be 80 A or less. This information should be specified on the welders name plate for each applicable weld modes.Regards,Mike"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 09:15:06 am",
"content": "True things are built to a price but with a Mig there is thefeatureof being able to weld until the wire spool runs out, theoretically. Stick welders on the other hand get a forced break each time you have to replace the electrode.I run my big 400 A 3 phase stick welder on a 20 A breaker, an ordinary one will trip in seconds @ 400 A but if you use a D curve motor rated breaker that permits a significant current overload for a fixed duration I can weld @ 300 A long enough to consume a full 5mm rod. By the time you've chipped and brushed the weld and replaced the rod the duty cycle starts over.BTW, in case you wonder why I have a 400 A welder....it was only $200 on a trolley and with longer than normal leads so couldn't resist buying it.Transarc 400 IIRC."
},
{
"post_id": "",
"author": "CaptainNomihodai",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 08:51:02 pm",
"content": "QuoteWhile this is true, and oh how I would love to have a nice inverter TIG setup, there's something to be said for the simplicity and durability of a good transformer. About a year ago I noticed that my open circuit voltage was too high. It took me about 30 seconds to figure out that the \"suppressor\" (just a resistor across the output terminals) had failed open. If I've got a Dynasty or Synchrowave (sorry, I speak Miller, not sure what the rest of the world has) that fails, fixing it would probably take a lot of help from people on this board. My current welder was built before I was born and, barring intentional damage or something catastrophic, will be working after I die. That being said, it also weighs significantly more than I do and would probably win in a fight, and uses enough electricity to power a small country, so ... tradeoffs.QuoteIn addition to what people have mentioned about MIG machines having caps on the secondary, some machines will also have capacitors for power factor correction. Unlikely here, though, this one sounds like a big box store model.QuoteYes. I open up my Miller and there are just 4 gargantuan diodes. I don't see why a sufficiently large bridge rectifier would be any different.Quote from: tautech on April 05, 2017, 09:15:06 am3 Phase, so that's 20A per phase on that breaker right? I've tripped 20A single phase breakers with a big angle grinder before...I'm not sure what I'm more jealous of, that you got that monster welder for such a steal (though, I can't think of a situation where I would actually need 400A), or your apparent access to 3 phase."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 08:54:11 pm",
"content": "Quote from: CaptainNomihodai on April 05, 2017, 08:51:02 pmThat is a valid point. I saw a guy once who had an arc welder that looked like it had been dredged up from the bottom of a lake after being run over by a truck. The thing still worked somehow."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 10:15:59 pm",
"content": "Quote from: CaptainNomihodai on April 05, 2017, 08:51:02 pmYep.QuoteD curve motor rated breakers and available in single phase versions too.Breakers to weaken with age, particularly if they've been tripped a good few times. A sparkie mate replaces a few that give trouble and then troubles are gone.QuoteTBH I rarely use it over 200 A but it's sure nice to know the extra grunt is there when and if you need it.3 pase is something that I would be reluctant to be without as so much older 3 ph gear is available at low pricing as the market for them is smaller. If you have 3 ph there are bargains to be had."
},
{
"post_id": "",
"author": "moz",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 10:28:59 pm",
"content": "Quote from: tautech on April 05, 2017, 10:15:59 pmHeysoos! I had a 180A TIG that I think I only ran at 180A once (welding 25mm reinforcing rod). Albeit I mostly build bicycles, the only real jobs I do bigger than that are the usual \"I have a workshop so I can build things for my workshop\" stuff. Then I sold it to MakerSpace because I barely use it, and if it's in there I can go and have access to a much better workshop than I can fit in my shed (or afford/justify).I have a 15A breaker that I plug in when I want to run the welder, the rest of the time I leave the 25A breaker in. Purely because the wiring in this house is a joke but I'm still saving up to fix it. 25A at random spots about the house, sure. 25A continuous to the far end of the property I am not so sure about. The loopback resistance on the garage circuit makes me doubt it's a single length of 2.5mm^2 cable the whole way (or it's running 100m of cable to cover 50m)."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2017, 10:32:50 pm",
"content": "Quote from: james_s on April 05, 2017, 08:54:11 pmDid it look like any of these transformers?http://halbot.haluze.sk/?id=3555https://expatinaddis.wordpress.com/"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 06, 2017, 12:21:47 am",
"content": "Yeah I think that's the one I was thinking of, that's nuts!"
}
] |
2025-10-17T18:59:23.201901
| 32
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1206-footprint/
|
1206 footprint - Page 1
|
[
{
"post_id": "",
"author": "Aztlanpz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 24, 2018, 11:31:48 am",
"content": "Is there a difference from a 1206 footprint for a resistor versus a capacitor?"
},
{
"post_id": "",
"author": "jct",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 24, 2018, 01:01:33 pm",
"content": "I've been using the same footprint for both, no problems experienced during flow soldering."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 24, 2018, 02:32:18 pm",
"content": "There doesn't need to be, no.If there is, it's usually that the capacitor has wider pads, or less pad gap, owing to the less-well-controlled tolerances on the end cap metallization, and the fact that it wraps around. Whereas resistors almost never have wrap-around metallization, but curled around the ends, so there is never a side fillet.Beware of specialty resistors, often low value current sense / shunt types for instance, have differently shaped ends, and will benefit from much less pad gap, or side fillet, or etc. (Also consider heat sinking methods for power resistors, which having somewhat larger pads helps with.)Refer to IPC-7351 (old versions are available free online) for terminology and how to calculate fillets, pad sizes and all that. It varies with lead and package type, but the most common are easy to remember.Tim"
},
{
"post_id": "",
"author": "BocaDev",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 25, 2018, 12:16:05 am",
"content": "QuoteI use the standard 1206 footprint for both. To help our assembly people if the board will be hand soldered, I place a silk screen R or C in the center of the footprint, just large enough to read. Assembly says it does help them to differentiate between a chip capacitor or resistor."
}
] |
2025-10-17T18:23:06.097857
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120khz-oscillation-in-received-dali-signal/
|
120kHz oscillation in received DALI signal - Page 1
|
[
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 01, 2019, 11:47:14 am",
"content": "Hi,We have a DALI communication setup. To be brief, DALI is basically square wave transmissions at 1200Hz.A DALI bus is pulled down and released at the 1200Hz frequency, as in the attached schematic. (LTspice sim also attached)In our DALI circuit, the node RA3 is following the transmission of the DALI bus, and is obviously an inverted form of it…however, within the high-going pulses at RA3, there is an approximately 120kHz oscillation….which is rendering the comms not working.I believe that this 120kHz oscillation is caused by the fact that due to the bridge rectifier, the DALI bus is not fully getting actively pulled down (after the bridge) for the “Low” pulses, and therefore the NPN at RA3 is turning on and off repeatedly at 120kHz as its base current starts to fall to around its off level.Would you agree, that the best way to stop this oscillation would be to reduce the Base_emitter resistor down to 1k? (This would also mean reducing the resistor R18 down to 2k2 so that the voltage isn’t divided down so much. R18 and R19 are 0603 size)The attached simulation doesn’t show this unwanted 120kHz oscillation happening.(by the way, there is also a 60W offline led driver SMPS on the same PCB as the DALI receiver part of the circuit shown)"
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 01, 2019, 12:31:07 pm",
"content": "By the way, the attached shows the 120khz noise we are seeing at RA3.Top is what it should be, bottom is what we getThis shows (on pg 3), the DALI idea we took our circuit offhttp://ww1.microchip.com/downloads/en/AppNotes/01465A.pdf"
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2019, 12:56:53 pm",
"content": "Read the actual DALI spec man!There are rise and fall time requirements, which you clearly don't meet, at least if your thing is using literally that spice circuit.There are also isolation requirements.... (And as a QOI issue you probably want to make the thing proof against getting mains up it, somebodywillcock it up that way).120kHz is a really odd frequency for something like this to take off at, so I am suspicious, what frequency is your switcher running that drives the LEDs? Also is this noise just on the receiver output or are you also seeing it on the DALI bus (Could be the transmit circuit or even the current source oscillating)?Now given the presence of that zenner diode the bridge rectifier should be a non issue, but with 10k as base/emitter resistor the current to start that transistor into conduction is only going to be 70uA or so, (0.7V/10k) which feels horribly low for a zenner diode. I would want more like a mA or so down that chain if I was doing it that way, but really there are far more reasonable DALI circuits out there, that is a pathetic attempt. A quick fix would be putting something like a couple of silicon diodes in series with the base to raise the threshold voltage a bit, but really, do it right.DALI is not a difficult physical layer so I dont really understand why people have so many problems with it."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 01, 2019, 07:11:03 pm",
"content": "QuoteScoping the DALI bus at the transmitter output..its clean. No 120kHz oscillation there.The switcher is variable F(sw)......75-100kHzQuotethanks, the DALI receiver is on the secondary side of a fully isolated 60w smps.The transmitter is powered by a wall wart output with full mains isolation.QuoteThanks, but how is our circuit so badly different from page three of this?...http://ww1.microchip.com/downloads/en/AppNotes/01465A.pdfI think if the post bridge rectifier DALI bus was getting fully pulled down to ground, then I suspect we wouldn’t have the problem?..But we initially didnt want to add components to do that as it would have been more cost."
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2019, 07:50:15 pm",
"content": "What is it with you and insane (not to say inane) sensitivity to BOM cost?That circuit is NOTHING at all like the one on page 3 of the microchip datasheet (Which in any case is a demo board circuit and probably not a good idea in real products), for one thing yours has significant gain on the receiver which the microchip circuit does not.Given your perpetual problems with getting stuff past EMC I would also strongly suggest that providing a large loop for common mode to travel might not be the worlds best plan, I would have the optos back in, also a couple of caps to slow the transmit edges a lot would not hurt anything.Regards, Dan."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 01, 2019, 08:55:37 pm",
"content": "QuoteThanks, what about the following adjustment?…now we have reduced the gain of the first NPN stage, making it a follower. We have also made the base_emitter resistor 10 times less.(pdf schem and LTspice sim attached)On the previous board, the original circuit of the top post worked absolutely fine, but we did not have the bridge rectifier then."
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2019, 09:16:08 pm",
"content": "Complicated much?Also I don't think that meets the 2mA maximum load imposed by the DALI spec at maximum bus voltage.I would probably have gone with the original (more or less) and just stacked a couple of diode junctions in series with the base connection (And maybe reduced the bottom resistor a bit or added a second one between the diodes and the base).The objective is to put the switching threshold at about 9V IIRC.If I was going to blow two transistors on the problem I would be thinking long tailed pair set up as a schmitt trigger, but it is overkill.Regards, Dan."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 01, 2019, 09:19:48 pm",
"content": "QuoteThanks, thats a good point, sorry i forgot to say that in this case, there is only one device on the dali bus."
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2019, 09:36:30 pm",
"content": "Then it ain't DALI and you might as well use something trivial serial.Regards, Dan."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 01, 2019, 09:45:26 pm",
"content": "Thanks, the DALI devices that our customers buy (to use as the transmitter you see in our schem) use DALI so we have to have the DALI protocol."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 02, 2019, 10:51:04 am",
"content": "QuoteThanks, that sounds like the best shot for us. The diode junctions will help because eg 1n4148's have very little leakage, so the leakage thats coming through the zener wont be able to get through the stackjed diodes so easily.And for that bit of leakage that does get through, the lower value base_emitter resistor will bleed it away.Thanks.I am hoping, in the first instance, that we can solve it by just putting a 3k9 across the dali bus (post bridge) and also by reducing base_emitter resistor to 1k (that means we have to reduce the top resistor to 2k2 so as to reduce the potential divider effect)....these changes we can do without re-spinning the board.If it doesnt work, then we will have to come in with the diodes on the re-spun board, , and also possibly a base_emitter capacitor of some 1nF."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 02, 2019, 11:35:30 am",
"content": "The attached (pdf schem and LTspice sim) are all the possible ways of fixing this DALI comms (Tx and RX) circuit.....we hope we only have to resort to circuit \"A\""
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 02, 2019, 01:07:41 pm",
"content": "by the way, the following circuit also works fine, but we dont want a bulky opto in there as we dont need the isolation.(ltspice and pdf attached)"
}
] |
2025-10-17T18:09:27.046808
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120ohm-imbedance-line-to-50ohm-oscilloscope/
|
120ohm imbedance line to 50ohm oscilloscope - Page 1
|
[
{
"post_id": "",
"author": "veeti",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 20, 2022, 04:26:40 am",
"content": "HelloI’m starting to debug/reverse engineering CAN bus,and i’m not sure how to deal with line imbedance.Can I just make custom cable with BNC connector which is ”shunted” with 120ohm resistor and take test lead from there?I allso have 2pcs MCP2515 connected to arduino and raspberry pi - and have been able to make data moving. But i would like to see signals allso in a scope screen.br: veeti"
},
{
"post_id": "",
"author": "jonpaul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 04:45:17 am",
"content": "balanced differential 120 Ohm TP line.Ideal is a differential probeAs drawing the BNC will short one side to groundUse two 10X probes, set-up scope for differential CHA-CHBUnawares if Chinese scopes have such a function (or INV B) as do most Tektronix scopes or old analogAlternative Use a pulse transformer or differential line receiverSee Tektronix Circuits Concept book Oscilloscope Probe CircuitsAlso théorie and practical differential balanced transmissionBon courageJon"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 04:49:47 am",
"content": "Don't overthink it.To check signal integrity just use one 10x probe on each side to see that signals are symmetrical. No need for math functions.To decode just pick any side and assume that the other one is complimentary.And decoding is far better with a logic analyzer anyway."
},
{
"post_id": "",
"author": "pcprogrammer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 05:04:00 am",
"content": "The original poster shows a Siglent SDS1102X-E in his picture which as far as I can tell, has selectable input impedance of 50Ohm and 1MOhm.I'm no expert here, but think the 1MOhm option with a normal 10x probe should be used instead of 50Ohm option with a normal 10x probe?And for the 50Ohm setting an active probe is needed?"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 05:11:01 am",
"content": "Yes, you need 1 M input and 10x probe."
},
{
"post_id": "",
"author": "veeti",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 20, 2022, 06:22:53 am",
"content": "Thanks for fast response.But if I use high impedance and probe - why there wouldn’t be reflection back to the line?Standard says max 30cm line without termination, and now i would have 1Megaohm termination with 1meter cable."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 06:28:21 am",
"content": "Your line is terminated by the actual termination resistors on the bus. The bus would not even notice your 1 MOhm \"load\" even with 1x probe."
},
{
"post_id": "",
"author": "exmadscientist",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 07:04:17 am",
"content": "Quote from: ataradov on August 20, 2022, 04:49:47 amPeople grossly overestimate how much this stuff matters.Yes, when conductors are long compared to the bit rate / edge rate you want to do it right. But how often are you doing gigabit links or kilometer cables? And if you're using a scope, if you get it wrong, you cansee it on the scope, it's not like it'll be waiting to bite you later. (Though youcanget bit if you forget that having the probe there changes things a little.)This also shows up in controlled impedance on PCBs. You just don't need it for a lot of things, \"best effort\" (take your stackup, calculate your widths, use 'em, and forget about it) is good enough up through even USB 2.0 High Speed, as long as the rest of the environment is gentle enough. Which it usually is."
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 07:19:37 am",
"content": "Quote from: veeti on August 20, 2022, 04:26:40 amyes, you can use 120Ω termination resistor, but in such case you're needs to use high impedance input (1 MΩ).If you use 50 Ω input on 120 Ω termiantor, the actual load will be 1/(1/50+1/120) = 35.29 Ω.If you're needs to use it with 50 Ω input, then you're needs to measure it through 120-50= 70 Ω resistor (connected in series with 50 Ω oscilloscope input).Another way is to use attenuator, see attachment for 10 dB and 20 dB attenuators. The 20 dB one can be used with 1:10 settings on oscilloscope to see actual voltage levels."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 07:23:36 am",
"content": "But that's not how CAN works. CAN bus is terminated by 120 Ohm resistors on two ends. That's all. Your scope should not add more \"termination\".You are just making it complicated for no reason at all. Just stick a scope on the bus and see that it all works and you just see what happens on the bus."
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 07:34:32 am",
"content": "Quote from: veeti on August 20, 2022, 06:22:53 amif you use high impedance probe, your CAN line needs to be terminated. It is already terminated if it's connected to another receiver with 120 Ω input. If you're needs to measure line which is not connected to anything, then you're needs to put 120 Ω termination resistor with high impedance input or use oscilloscope with proper input impedance.If you're want to measure 120 Ω line which is already terminated by another receiver, then oscilloscope with 50 Ω input is not suitable for you, because when you tap your 50 Ω probe to already terminated 120 Ω line, the point where you tap the probe will have 35 Ω impedance and as result it leads to wave reflection.Also note, when you use high impedance probe, it has bandwidth limitation. So, if you want to see more high frequency details, it's better to use 50 Ω input with proper attenuator. But it will works when your line is not connected to anything else, this way will not work if your line is already terminated with another receiver. When the line is already terminated, the only way is to use high impedance probe.In simple words, if you're needs to catch transmission between devices, then just use high impedance probe. If you're want to measure parameters of device output which is not connected to anything else, then you're needs to use proper terminator resistor with high impedance oscilloscope input or use proper attenuator with 50 Ω oscilloscope input.The main idea is that endpoint of line needs to have proper 120 Ω resistance (for 120 Ω line) which include resistance of the oscilloscope probe. If oscilloscope probe has too low resistance you can add resistor in series to get actual 120 Ω. If oscilloscope probe has too high resistance, you're needs to add resistor in parallel to get actual 120 Ω. This is how it works.Also note that resistor should not be inductive. Some kind of resistors can have too high inductance and can't be used. Use RF grade resistors or at least film type with no winding for such purposes. SMD resistors bellow 200 Ω usually works ok up to 50-100 MHz and even more."
},
{
"post_id": "",
"author": "Wallace Gasiewicz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 12:23:01 pm",
"content": "If you wish to terminate your 120 ohm line into the 50 ohm input of your scope, you can add a 70 ohm resistor in SERIES with the input. (not to ground). I think radiolistener stated this.You could make up some sort of connector with the 70 ohm resistor in it. As pointed out, you need a resistor that is not too reactive.I think you could put a regular axial lead resistor in the center pin of a BNC connector and jam it into the center coax wire and solder it. It might just fit into the BNC, if you trim the center just right.....If you wish to terminate the 120 ohm output into the high impedance scope input, use 120 ohms to ground.However if your 120 ohm signal is already terminated into another device, use 10X probes with the high impedance scope input. Lots easier."
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 09:21:47 pm",
"content": "Quote from: veeti on August 20, 2022, 06:22:53 amI think what is confusing you (and seems to be not explained by others) is that scope probe is NOT your typical coax cable. It has special construction and it is made to be deliberately a lossy transmission line (center wire is highly resistive). This transmission line is carefully crafted to have wide and flat frequency response and minimal reflection impact.This is of course the reason why we can use it to probe things quite universally. If your scope probe would me made from standard 50 Ohms cable and matching termination at the scope end, it would be useless for most of everyday circuit probing, causing loading. And if unterminated at the scope end, it would also be useless because of all reflections, ringing and garbage frequency response."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 20, 2022, 11:52:10 pm",
"content": "Quote from: veeti on August 20, 2022, 06:22:53 amThe line is already terminated at each end in the circuit. A high impedance x10 probe can be attached anywhere because it will only present like 10 picofarads of capacitance."
},
{
"post_id": "",
"author": "jonpaul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 21, 2022, 07:39:30 pm",
"content": "Bonjour: The CAN bus is similar to RS-232, RS-485, AES/EBU, with a differentledrive to a twisted pair lik Ethernet cable UTP or TP.Most of the TP cables are designed for Zo 100..110..120 Ohms Differentl, ie the ter reisitor is line to line NOT line to return.Probing the TX or RX sides is easy with 10X probes into a 1M scope.At these rates a 50 Ohm scope and cax is NEVER required.Two probels can be used diffreretially if the scipe has CHA - CHB function.But one seldom see a hug imbalalnce so just one probe, moved from L1 ro L2 is enough to see the leves and edges.As the RS-485 RX IC has some hysterysis, noise is somewhat rejected.See the CAN bus spec, RS-485 TX and RX IC specs and excellent app notes of Belden Cable by Steve Lampen for balanced TP cable and transmission. .Vehicle cable runs are typically 1m to 5m but theenvironment is VERY noise with EMI and high amplited transients.Finally i have written AES , SMPTE and NAB papers since 1995, on the topics of digital audio transmission and cables and transformers, the baud rate is 6.144 MB to 24.576 MB.Ciao!Jon"
}
] |
2025-10-17T17:06:38.887143
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120v-240v-transformer-question/
|
120V / 240V Transformer question - Page 1
|
[
{
"post_id": "",
"author": "made2hack",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 12, 2014, 09:23:56 am",
"content": "Hello,So, I've got a 120V/24V 60VA transformer that I took out of my Hakko fx888d North American version. I replaced it with a 240V/24V 60VA transformer here in the EU.My question is, what can I now do with this 120V Transformer?Let us first assume the following:Turns Primary = Tp , Turns Secondary = Ts, Voltage Primary = Vp, Voltage Seconday = VsLet's also assume that Tp = 120 turns, or 1V/Turn. Thus, we know Vp = 120, Vs = 24, Tp = 120And, Ts = (Vs x Tp) / VpPlugging for Ts = (24x120) / 120, so Turns Secondary = 24 Turns.Now, if I am now connecting the transformer to 240VAC (220-240), does the following occur?Vs = (Ts x Tp) / Vp, or Vs = (24x120) / 240 = Voltage Primary = 12 V? Will I get 12V out of the secondary, ALL THINGS BEING EQUAL, if I simply plug in the 120VAC transformer to 240VAC?Does it essentially divide the secondary voltage by 1/2? This is also a center tapped transformer on the secondary, so in essence it is as 2x12. Will I now get a 2x6V?What happens to the power rating? This is a 60VA transformer, or 120V @ 0.5A primary and 24V @ 2.5A on the secondary.If I plugin 240V, obviously the primary side has wires that are thicker than needed, since I am now only putting through 0.25A. But the secondary, technically has \"thinner\" wires designed for the 24V. Am I now running 5A through the secondary?Will this mean that, ALL THINGS BEING EQUAL, that I have reduced the VA by half? To keep things safe?Hope I explained things clearly."
},
{
"post_id": "",
"author": "Zepnat",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 12, 2014, 10:13:33 am",
"content": "You still need to maintain that assumed '1v per turn' on the primary. Double the primary turns to cope with double the voltage or else it will release the magic smoke verry quickly."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 12, 2014, 10:37:19 am",
"content": "Simplest is to take it, hit with a hammer to loosen the varnish and remove the laminates, then unwind the copper. Take all down to scrap and you will get around $6 for the lot.Running a 120V transformer on 220V is a very quick way to have a room full of nasty smelling black smoke and a tripped mains breaker. The other way round it will work, but not with a higher voltage than the designed spec.I have a very nice variac that has a 5A rating, but unfortunately it is designed for 115VAC 400Hz operation. However it has the right ratio such that it works very well with a supply of 12VAC 50Hz, and I use it as a variable AC supply capable of delivering up to 12VAC at up to 5A. I used it a lot as a room lamp dimmer with a 12V 50W halogen lamp, and it was variable from barely glowing red to bright."
},
{
"post_id": "",
"author": "edy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 12, 2014, 11:21:26 am",
"content": "If you have 120 V transforming to 24 V, wouldn't doubling the input also double the output? So you would get 240 V going to 48 V? Just intuitively without doing any math... Never mind the current, which again intuitively should also increase given the same load because you have double the potential difference across it.... and higher current will heat/melt the wires?"
},
{
"post_id": "",
"author": "miguelvp",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 12, 2014, 11:22:49 am",
"content": "Edy is right it won't half the voltage it will double it.Vp/Vs = Np/NsNp/Ns (turn ratio) in your case:120/24 = 5.Moving the turn ratio to the left (divide) and the Voltage for the secondary to the right (multiply)Vp/5 = VsSo:240V/5 = 48VBut like the others comments mention, you can't current limit your mains so it will get really hot really fast dissolving the varnish and melting the wire, shorting and probably catching on fire.Reversing it might have some use if you ever have some AC power from 0 to 24V that you need to multiply by 5.Then there is the whole magnetic saturation the core can handle to take into account."
},
{
"post_id": "",
"author": "mij59",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 12, 2014, 11:42:32 am",
"content": "The core of the transformer will be driven in to saturation (search for bh curve), inductance will decrease, and current will increase a lot.Even with transformers rated for 220V and connected to 240V this can be a problem."
},
{
"post_id": "",
"author": "sunnyhighway",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 12, 2014, 04:27:57 pm",
"content": "Quote from: trs80 on July 12, 2014, 09:23:56 amNot much I'm afraid.But if you are a stickler for money, just rip out the copper wires, scrape off the varnish and use it for etch repairs.You can use the core as a paperweight."
}
] |
2025-10-17T19:59:00.830208
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120v-ac-air-pump-connect-to-240v-is-that-a-bad-idea/
|
120V AC Air Pump connect to 240V, is that a bad idea? - Page 1
|
[
{
"post_id": "",
"author": "amergen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 29, 2023, 05:25:30 am",
"content": "Hi Guys,I recently purchased Scalpfun S9 Laser engraver with Air Assist. The problem is the air pump, it says on it 120V 60Hz which we all know is for the US market and not Australia. So for the last 2 weeks, I've been in communication with the supplier, informing him that he send me the wrong voltage air pump, explaining in detail about Australian 240V requirements. However, he kept insisting that it will work on 240V as well! He sent me US to AU plug converter, and said to use that to connect to AU socket!This has been going on for 2 weeks, so I finally said, if I plug the unit into 240V will you take responsibility? And of course, he said yes, so I did yesterday (with a fire extinguisher ready) and to my surprise, it worked! The pump model is Scalpfun AP30A, see pictures. I believe it's a piston pump driven by an electric motor.So my question here is (Q) What is going on here, will this pump/motor be damaged in the short/long term?Much appreciated for your help, Regards Gordon."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 29, 2023, 09:41:42 am",
"content": "Of course it will work, but for how long, 50/60Hz is a problem in itself as at a lower frequency the same coil will have less impedance and let more current flow. Then you also double the voltage. Now it could be one of those situations where given the small power level although in absolute terms it's much more heat it may handle it in relative terms to the electromagnet. It's like the old phone chargers that had a center tapped transformer with just two rectifier diodes therefore wasting half the power availability. But on such a small transformer it would probably have been the same expense to make a non center tapped transformer but 2 more diodes were required. It could be a similar logic here. However the manufacturer has marked it for one voltage and frequency.As for the seller being liable, well try suing them when your house burns down, you will get no justice over a foreign entity. I would be very careful. This is why it is more ideal to import stuff so that you have a local importer to point your local authorities to. But often they do not care either. Here in the UK trading standards have been whittled down to something that joe public can no longer talk to so it's hard to report issues and so the few people left can get on with the now reduced work load."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 29, 2023, 09:50:54 am",
"content": "Is it actually connected to 240V directly?"
},
{
"post_id": "",
"author": "amergen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 29, 2023, 12:15:48 pm",
"content": "Yes, it does.I also have a variable transformer (variac) that can go from 100V to 250V and tested at both 120 & 240, at 120V it sounded OK, however, it was noticeable at 240V it was making a crackling, humming noise, but it was pumping air, but I switch it off fearing any damage.Regards,Gordon"
},
{
"post_id": "",
"author": "tunk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2023, 12:25:38 pm",
"content": "How much power does it draw at 120V and 230V?If it's significantly higher at 230V then it may be a problem.Would it be possible to use a resistor in series to drop 110V?"
},
{
"post_id": "",
"author": "wasedadoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2023, 12:28:06 pm",
"content": "Are you talking to the manufacturer -https://sculpfun.com/pages/contact-us- or a seller?"
},
{
"post_id": "",
"author": "amergen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 30, 2023, 08:39:28 pm",
"content": "Yes of course, if you look at my initial post, it has been a painful two weeks of gross \"misunderstandings\"until now no resolution, however, Aliexpress is now \"stepping in\", I don't know what that means, is that to help the supplier or me?"
},
{
"post_id": "",
"author": "amergen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 30, 2023, 08:47:02 pm",
"content": "Good suggestion, I will measure power consumption at 120V and 240V, however using a resister to reduce the voltage from 240 to 120 is a huge waste of power, better to use a step-down transformer, but that is an additional $$ and it's not a good long term solution."
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 30, 2023, 09:16:34 pm",
"content": "Are the two coils wired in parallel or series?"
},
{
"post_id": "",
"author": "inse",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 31, 2023, 04:39:31 am",
"content": "Judging by photo #1, I would say in series.You can add a capacitor in the 4uF range as dropper in series with the pump. You might need some experimenting to determine the best value as the pump is not a resistive load and we don’t know it’s inductance.But maybe it’s not that critical…Above that you don’t need to worry about burning down your house as there is obviously a thermal fuse at the winding.Let it run and check the winding temperature - above 100C things get critical"
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 31, 2023, 04:43:02 am",
"content": "But photo #1 I think is from a marketing ad, I thought maybe a 240VAC version with coils in series."
},
{
"post_id": "",
"author": "amergen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 31, 2023, 09:46:22 pm",
"content": "Hi, thanks for all your feedback & comments.Yesterday I had the opportunity to open the pump up, and I've included some pictures.It seems the 2 coils are connected in series, also the motor is speed controlled by a TRIAC BT136, this triac is rated 600V @ 4A, maybe by using this we can reduce the voltage to a safe level, but also try not to overhead the triac and waste energy. I will need to do more experimenting this weekend.In the meantime NO feedback from the supplier or Aliexpress for a replacement or partial refund.Regards,Gordon"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 01, 2023, 04:27:43 pm",
"content": "is the speed variable?"
},
{
"post_id": "",
"author": "amergen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 05, 2023, 06:40:38 am",
"content": "Hi All, quick updates.1. Aliexpress has finally stepped in and decided that the supplier was in the wrong and has already refunded me the full amount for the air pump including delivery!2. I have tested the air pump with 120V & 240V AC (using a variac & watt meter), here are the results:o. @120V min speed 109mA & max speed 162mAo. @240V min speed 342mA & max speed 432mA, the air pressure was noticeably much greator.3. I let the pump run for 10 minutes @240V min speed, and the temperature reached 40 degrees Celsius, did the same at 120V it was cooler at 27 degrees.In summary, I'll use the current pump at 240V low speed until it craps out, in the meantime I will order a new one, hopefully, this time it will be a 240V version.I was glad aliexpress resolved this pointless debate between me and the supplier, I am not sure if it is because of English or the supplier playing dumb.Anyway, thanks for your help and comments."
},
{
"post_id": "",
"author": "barshatriplee",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "June 05, 2023, 07:07:06 am",
"content": "You need a step-down transformer like this:https://www.amazon.com/Watt-Step-Down-Converter-International/dp/B086H3DXF1/ref=sr_1_1?keywords=240v+to+120v+converter&qid=1685948539&sr=8-1"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 09, 2023, 07:19:06 pm",
"content": "Quote from: amergen on June 05, 2023, 06:40:38 amThe supplier is chinese, playing dumb and wanting to rip you off are both a factor.I suspect hat the pump will always run with the frequency, it is coils right? it will oscillate the diaphragm pump at the frequency supplied. but at 240V you see you get more current, so more deflaction so greater volume with each cycle. But (342/109)^2 = 9.84 times the heat."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2023, 07:45:29 pm",
"content": "That sounds like an electromagnet-driven reciprocating pump with a phase angle control. As others have mentioned, the winding temperature is the most important thing to monitor. If you have a logging temperature sensor it would be useful to see if the temperature gets to dangerous levels or just rises more quickly and stabilises at a higher but still safe (which can still be too hot to touch) temperature."
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2023, 08:27:16 pm",
"content": "I actually use that trick, but for a different purpose. I put a capacitor in series with 240V muffin fans so I can use them on 120V AC. Choosing the right capacitor will develop about 180V on the motor. I don't like loud fans and that voltage slows them down enough.Remember what happens to voltage when a capacitor and inductor are near resonance. A capacitor in series can easily burn out a motor."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 09, 2023, 10:50:23 pm",
"content": "I think I would just pick up a cheap transformer based travel converter and toss that in there, shouldn't cost more than about 20 bucks for one that is good enough quality to at least not catch on fire. The pump only draws about 20 watts so one of the common 50W buck transformers meant for shavers and such ought to work fine. The pump may in fact tolerate being overdriven and run like that for years without failing, but why chance it?"
},
{
"post_id": "",
"author": "amergen",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 10, 2023, 08:56:02 am",
"content": "Hi Guys,Thanks for your feedback, I've finally decided to purchase a small low-cost 150W stepdown transformer (this onehttps://tinyurl.com/mr3haat9) instead of buying another air pump, with a total savings of just under a hundred dollars, thanks to my \"play dumb\" supplier.I think running it at 120V will definitely increase its lifespan. Overall I am happy with the outcome, now I can finally focus on what I really bought this laser engraver for, and that is engraving! Cheers!"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 12, 2023, 09:04:58 pm",
"content": "I seriously doubt that transformer is capable of anywhere near 150 watts, but for your needs it will probably be work perfectly."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 13, 2023, 06:53:18 am",
"content": "150W PMPO ?"
},
{
"post_id": "",
"author": "EPAIII",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 13, 2023, 08:58:25 am",
"content": "A series resistor may waste power, but not as much as running it directly on 220V.220V direct connection:Rp = effective resistance of pumpPower used = 220^2 / Rp = 48400 / Rp220V connection with resistor:Rp = effective resistance of pumpRs = series resistance = RpPower used = 220^2 / (Rp + Rs) = 48400 / 2Rp = 24200 / RpThe series resistor cuts the total power IN HALF. The direct connection to 220 V is clearly the biggest power waster.Of course, a transformer will cut the wasted power even more. But transformers cost a LOT more than resistors. That extra cost also represents a waste of power and/or resources. Care to do a \"break even\" calculation?And if it goes up in smoke then there is the replacement cost for the overall device. And possibly for whatever else catches fire.I would NOT run it directly on 220 Volts. Either of the options is clearly a better one than that.BTW, just why is a step down transformer such a bad long term solution? Other than cost, of course.Quote from: amergen on May 30, 2023, 08:47:02 pm"
},
{
"post_id": "",
"author": "inse",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 17, 2023, 06:17:18 am",
"content": "CAPACITIVE DROPPER is the way to go"
}
] |
2025-10-17T16:53:25.437011
| 24
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120v-ac-ssr-resistance-question/
|
120v AC SSR resistance question - Page 1
|
[
{
"post_id": "",
"author": "smssk",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 20, 2024, 12:09:44 am",
"content": "How do I go about calculating the required resistance to drop 120v AC down to 1.4v DC to drive the SSR in the attached circuit at approximately 15ma?"
},
{
"post_id": "",
"author": "Konkedout",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 20, 2024, 03:55:18 am",
"content": "1) Think current instead of voltage. The LED operates at a relatively constant voltage which is small compared to the incoming voltage. It wants to be fed by current; not voltage. How much current do you want? Maybe 10 - 20 mA?? Well OK 15 mA...read below:2) Thinking that way; use a simulator!! LTSpice would work, or I could even simulate it with Excel if I wanted to spend the time. Use the simulator to determine how much current you get through the LED, depending upon input voltage and series resistance.3) I think that the zener D3 will do no good and may well interfere with circuit operation.4) Finally...it may be better to use only one dropping resistor in series with the LED. Use a capacitor at C2 that is rated at 200 or 250 VDC. You might be able to use a 1 uF film type for example. If you do this than you would need one series resistor of about 10K or 12K. But this needs to be (conservative) a 10W rated resistor. Best to use a step down transformer or low voltage power supply to drive the LED. Did you throw away that power adapter from your old cordless phone?"
},
{
"post_id": "",
"author": "johansen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 20, 2024, 04:55:15 am",
"content": "On the order of a .1uf capacitor in series with a bridge rectifier will provide tens of milliamps at constant current. Use the capacitive reactance calculator, put a resistor in series, and a zener to protect the led from power surges.If you just use a resistor then you have to dissipate 10ma times 120vac.You can probably buy 120vac input SSR relays for less than the time to figure out how to build your own."
},
{
"post_id": "",
"author": "Andy Chee",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 20, 2024, 06:23:07 am",
"content": "Quote from: smssk on January 20, 2024, 12:09:44 amHave a read here, particularly the capacitive supply:https://ww1.microchip.com/downloads/en/appnotes/00954a.pdf"
},
{
"post_id": "",
"author": "BillyO",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 20, 2024, 09:07:51 pm",
"content": "I would consider a capacitive dropper instead. You will avoid the the dissipation issue."
}
] |
2025-10-17T16:41:46.692460
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120v-ac-to-12v-dc-converter-amperage/
|
120v AC to 12v DC Converter Amperage - Page 1
|
[
{
"post_id": "",
"author": "mezmiro",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 23, 2016, 08:21:10 am",
"content": "Hi there!I'm a noob to this forum (and somewhat to electronics design). I have more of a software background, and I'm still getting used to hardware. The project I'm working on now is building an automated coffee roaster. Because roasting coffee is awesome, and everyone should try it!I'm hoping you guys can help me out though.I currently have an Arduino Uno set up with a 16x2 LCD screen for menu display, along with two push buttons and a pot for menu navigation. The issue I'm having is with choosing the amperage I need for a power supply. It needs to supply the above components along with a stepper motor, converting 120vac from the wall to regulated 12vdc. I'm looking at a design similar to the attached photo.I have a few brushless DC motors to choose from in the range of 5v-12v, but how do I decide what amperage my power supply should be to supply this project? I can pull amperage ratings for every other component in this setup, but not for any of the motors. Do you have any advice on this? From what I have read, it's safe to operate components on a power supply that's well over the amperage you need (while not efficient), but it's not safe to go under. Is there a way that I can find the required amperage of these motors?Just for some context, the motor will be spinning a drive shaft attached to a stirring rod with paddles of sorts, which is set on top of a heated pan. The paddles stir up the beans while the heat is applied so that they are heated/roasted evenly. I have the code set up for various speed settings in the Arduino sketch I made, so the load will vary.Thanks for taking the time to look at this. I feel like I have most of this project down but this one is really stumping me.Here are the two motors I'm looking at using right now:https://www.adafruit.com/products/858https://www.adafruit.com/products/324"
},
{
"post_id": "",
"author": "jeroen79",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 24, 2016, 09:36:51 am",
"content": "The 12V one lists a max current of 350 mA.The 5V one is specified with a 42 ohm DC resistance.But if the specs don't tell you the current rating then you could always contact the seller and ask for more details.Or see if you can find the part's name and try to find a datasheet elsewhere.As a last resort you could buy the motors and test them.Make it turn with a resistor in series and then measure the voltage drop over that resistor. Be sure to test it with different loads."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 24, 2016, 09:57:51 pm",
"content": "One way of playing it safe could be to measure a coil resistance in the motor assist would give you the start-up current expected. It's a bit rough and ready but at least you won't under design."
}
] |
2025-10-17T19:26:05.950579
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120v-ssr-how-to-calculate-resistors/
|
120V SSR - How to calculate resistors? - Page 1
|
[
{
"post_id": "",
"author": "smssk",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 20, 2024, 12:07:27 am",
"content": "How do I go about calculating the required resistance to drop 120v AC down to 1.4v DC to drive the SSR at approximately 15ma in the attached circuit?"
},
{
"post_id": "",
"author": "Halcyon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 20, 2024, 05:22:37 am",
"content": "Duplicate thread."
}
] |
2025-10-17T16:42:02.784807
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120vac-leds-six-in-parallel-one-flickers/
|
120vac LEDs Six in parallel - One Flickers - Page 1
|
[
{
"post_id": "",
"author": "NY2KW",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 31, 2020, 04:25:07 am",
"content": "2 years ago I bought some very attractive, pricey, recessed stairwell LED lights. They are each wired 120vac in parallel and controlled by a regular wall switch. One of the lights now flickers rapidly when turned on and I have to flip the wall switch numerous times until it finally stays lit. I have monitored line voltage and it is pretty constant between 119-122vac. I cannot get a replacement fixture... is the LED assembly something potentially repairable?jerry"
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 31, 2020, 06:17:31 am",
"content": "Could be the driver circuit is getting ready to pack it in on that one or it could very well be a poor connection at that one.I would check the connections are solid and go from there.Can you get a couple photos inside the light fixture and if you can any circuit board."
}
] |
2025-10-17T17:56:48.168120
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120vac-triac-dimmer-211306/
|
120VAC TRIAC Dimmer - Page 1
|
[
{
"post_id": "",
"author": "vidarr",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 20, 2019, 01:57:24 pm",
"content": "Can someone check my schematic. I built the circuit and it is not working. I am getting power to the \"lamp\", but it is not adjusting with the potentiometer. The pot is brand new (all the parts are new). I double checked it with a DMM. I went over the built circuit while looking at the schematic and everything is connected properly according to it. The connections are all good according to the DMM.I did not make that schematic. So, maybe the problem is that? IDKThe circuit I built does NOT include the 12k resistor shown in one of the schematics.Thanks"
},
{
"post_id": "",
"author": "vidarr",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 20, 2019, 05:13:05 pm",
"content": "I built another circuit from scratch following the same schematic (but using the same potentiometer). I tested the output and it goes from 30V (all the way counterclockwise) to 42V (clockwise). This should be 0V to 120V right?edit:I retested the first circuit. It gives the same reading of 30V - 42V. So, this is a problem with the circuit design. The only common part is the potentiometer, which is brand new and tested.Checking other schematics online, many are similar to what I have. They all seem to be a little bit different though -- not any of them are the same.Maybe someone has a link to a schematic they Know is working?edit: I had the same problem with this circuit a while back and posted here. Back then, it had a bad potentiometer. Since then, I bought and changed out all the parts for new and still not working.Thanks"
},
{
"post_id": "",
"author": "soldar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 20, 2019, 06:57:33 pm",
"content": "With questions like this almost every time the schematic as shown is fine and there is an error in assembly that we cannot see.You need to double check that what you assembled is the same as what the schematic represents."
},
{
"post_id": "",
"author": "vidarr",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 20, 2019, 07:44:22 pm",
"content": "Yeah, I checked it many times. I built it twice from scratch -- I have TWO full circuits built based on the schematic and they both do the exact same thing.Both circuits built from the same schematic go from 30V with pot all the way counterclockwise, to 42V with the pot turned all the way clockwise.The schematic you attached has parts I don't think I have -- need to look. My plan was to take one of the circuits apart and build it based on another schematic I found. If I have the parts for the one you attached, I can try that.Is it possible that the schematic I am using is designed for 240V? I am in Brazil and we have 120V and 240V in our houses."
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 20, 2019, 08:30:01 pm",
"content": "Check you have not mixed up triac MT1 and MT2 pins. What is your capacitor valueI do not know \"1K400V\"looks like u1K400V = 0.1uF each.It needs to be about 47nF with 500k potentiometer or 0.1uF with 250k potentiometer, with 120VAC.I have had troubles with chinese triacs and potentiometers not working well or lasting long. Check your potentiometer is not burnt.A better circuit adds a bridge rectifier to give \"hysteresis free\" or \"no snapback\" effect, like you see with lamp dimmers. It's also helps with inductive loads. The extra diodes discharge (reset) the firing delay capacitor every cycle.More can be found in figure AN1003.12 orTeccor App note AN1003This is the eBay circuit for the \"4,000W SCR\" dimmer."
},
{
"post_id": "",
"author": "soldar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 20, 2019, 08:35:59 pm",
"content": "Quote from: vidarr on September 20, 2019, 05:13:05 pmThe schematic is good. It is pretty much the same found everywhere with minor variations.I would recommend you understand how it works so you can troubleshoot it.There have been many threads on the same circuit with the same problem: it doesn't work.You can do a search for triac dimmer power control etc."
},
{
"post_id": "",
"author": "soldar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 20, 2019, 08:44:24 pm",
"content": "Hey, I thought I remembered doing this before! You're the same guy!https://www.eevblog.com/forum/beginners/ac-dimmer-circuit/You just abandoned and now you start all over again?"
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 20, 2019, 08:50:45 pm",
"content": "Yeah, that thread ended after he found the potentiometer was bad and needed to replace it."
},
{
"post_id": "",
"author": "vidarr",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 20, 2019, 08:58:14 pm",
"content": "Yeah, the potentiometer was bad and I stopped. I wrote above that I posted here about it before and where I left off. I put the project on hold because this is a hobby and I had other things to do. So, now I am back at it where I left off.I just finished unsoldering one of the circuits. I am going to try an alternate circuit I found online. I WANT to understand the circuit. I understand what all the components do individually. I understand how the TRIAC and DIAC work together. I do NOT understand why the capacitor(s) and resistor(s) are sized the way they are and why they are placed the way they are. I see so much variation in the circuit designs that I can't figure it out."
},
{
"post_id": "",
"author": "vidarr",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 22, 2019, 05:59:44 pm",
"content": "Quote from: floobydust on September 20, 2019, 08:30:01 pmI tried another schematic very similar to what I had tried and it did not work. Finally, in frustration, I copied a schematic from one of these Indian made, YouTube videos. Watching how they solder is hilarious. Anyway, my theory was if these guys could make this work, there is no way I wasn't going to succeed. I ended up making two of the Indian guys' circuits I found and they both worked. Go figure.So, I know my parts are good at least. I am going to try the schematic under: \"Figure AN1003.9 Basic Diac-Triac Phase Control\" in the link you posted. If that works, I will move on to the circuit with the bridge rectifier, as you suggested would be better. Thanks for the link to that \"Phase Control Using Thyristors\" PDF. That was very helpful.Thanks"
}
] |
2025-10-17T18:03:12.340796
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/120vac-triac-dimmer/
|
120VAC TRIAC Dimmer - Page 1
|
[
{
"post_id": "",
"author": "vidarr",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 17, 2019, 04:42:02 pm",
"content": "Never Mind. I had coffee."
}
] |
2025-10-17T18:03:31.719778
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/121gw-as-phaseneutral-indicator/
|
121GW as phase/neutral indicator - Page 1
|
[
{
"post_id": "",
"author": "strawberry",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 27, 2023, 06:24:55 am",
"content": "AC volts range internal 10Mshunt resistor is less than ~100M neon indicator but same ~1kV breakdown specnegative led connected to ground or hand and positive test lead to somewhere"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 27, 2023, 11:46:29 am",
"content": "Holding the negative lead in your hand while probing the mains with the other would be an incredibly dangerous thing to do. The meter contains a VDR (voltage dependent resistor) to shunt high voltage transients and protect the meter. If you are holding the meter at the time of such a transient, it will go straight through you. You might also accidentally have the probe plugged into a current range jack!Holding the negative lead (actually it doesn't matter which way round as mains is AC) to ground, as long as you aresureit is ground rather, than Neutral is better. If you have a faulty ground though, you will get a false reading. The correct method to test for dead is Live-Neutral, Live-Earth, Neutral-Earth.If you are doing much of this sort of thing, then electricians' 2 pole testers are available for little money. These have decent CAT ratings, always work (no danger of wrong socket or dial setting) and even work with a flat battery (the ones with a continuity function too). Avoid handheld non contact 'death sticks' or meter NCV functions, their indications are not reliable enough to trust your life to! Handy for 'exploring' but nothing more.P.S. Neon screwdriver testers are not considered safe these days either."
},
{
"post_id": "",
"author": "strawberry",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 28, 2023, 05:27:20 pm",
"content": "I have admiral rank in engineeringMOV typically will subtract rated voltagespark gap and underrated components will short circuit and bypass full power"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 28, 2023, 07:09:25 pm",
"content": "Quote from: strawberry on August 28, 2023, 05:27:20 pmA strange question to ask then. Actually, trying to read your OP again, is it a question? It doesn't seem to make sense."
},
{
"post_id": "",
"author": "Vovk_Z",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 29, 2023, 08:06:26 am",
"content": "Quote from: Gyro on August 28, 2023, 07:09:25 pmIt is not a question. We are use to have questions here, but occasionally somebody just shares it's experience.BTW, I use a multimeter as a phase indicator often too (though I have neon indicator of cause but if often is lying somewhere else). Typically I don't have to touch ground, so it is mostly quite safe. Sometimes when floor and walls are fully isolated material it shows nothing. But mostly it shows at least 10-20 VAC at phase (and zero at neutral or PE)."
}
] |
2025-10-17T16:49:17.009418
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/121gw-meter/
|
121GW Meter - Page 1
|
[
{
"post_id": "",
"author": "Rob T",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 21, 2018, 06:43:42 pm",
"content": "Has anyone from Canada ordered this meter I was wondering how much it ended up costing"
},
{
"post_id": "",
"author": "GeoffreyF",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 21, 2018, 08:03:26 pm",
"content": "279.37 at today's exchange rate. Shipping charges also apply. You can calculate yourself here.https://www.google.com/search?q=australian+to+canadian+dollars&rlz=1C1CHBF_enUS721US721&oq=australian+to+canadian+dollars&aqs=chrome..69i57.5254j0j7&sourceid=chrome&ie=UTF-8It is well worth it for the feature set provided."
},
{
"post_id": "",
"author": "bc888",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 22, 2018, 02:51:15 pm",
"content": "It seems like the GW121 issues and problems thread has so much complaining that it's clear the meter is not ready for release yet. Is that not true? Meter is working fine?Need to add the link:https://www.eevblog.com/forum/testgear/eevblog-121gw-multimeter-issues/850/"
},
{
"post_id": "",
"author": "GeoffreyF",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 23, 2018, 02:24:43 am",
"content": "Quote from: bc888 on October 22, 2018, 02:51:15 pmNo it's not true. Much of that thread is regarding beta shipments, not released. I own one and it is really great for the money. It is stable and works great. There are meters more than twice the price with similar functions. Those more expensive settle on a value faster or handle multi-phase motors, capability valuable for someone who is solving problems in the field.The 121GW is out of stock. When it becomes available, it gets sold out in a day or so."
},
{
"post_id": "",
"author": "NexusKoolaid",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 23, 2018, 04:30:26 am",
"content": "You can also order this meter from Welectron (in Germany). Welectron is out of stock as well at the moment, but it looks like more are expected on the 26th of this month. He's fast - I ordered a Brymen 867s on a Friday evening (US), it was at my door the following Tuesday. You don't have to pay the VAT when ordering from North America, but the only shipment options offered are DHL and UPS.https://www.welectron.com/EEVBlog-121GW-Data-Logging-Multimeter-with-Bluetooth"
}
] |
2025-10-17T18:23:11.214006
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/121gw-multimeter-bluetooth-logging-sample-rate/
|
121GW Multimeter - Bluetooth Logging Sample rate - Page 1
|
[
{
"post_id": "",
"author": "Ted123",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 01, 2024, 09:36:20 am",
"content": "Hi allI've just recently got the 121 GW multimeter, pretty happy so far.I did a uA test for the flame rectification check on a flame rod on gas heater, seemed to work well and was getting around 3 uA which sounds about right.I tried to do a cranking test on my car battery with the Bluetooth logging to see what the minimum cranking voltage it got. It seems to be around 10.3 volts as per the photos. 12.6 standing voltage, 10.3 cranking, 14.1 charging as per the photo. What is the sampling rate of the Bluetooth logging (how often does it take a reading) I had it on the ln0 setting and would this be a reliable test ?I have to say the set up and connecting of the app and Bluetooth for a novice and non EE like me.I tried to do the min and max reading but it kept saying 0 volt so I must have been doing wrong"
},
{
"post_id": "",
"author": "J-R",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 01, 2024, 09:33:09 pm",
"content": "A typical DMM and this logging method in particular are going to be a bit slow for capturing a lot of detail. I'm not sure what you're trying to see, but you could pull your fuel pump fuse or otherwise prevent the car from starting to extend the cranking time.Another method: if you have an oscilloscope or DMM with a scope function, you could gather multiple seconds on the screen at great detail. For better accuracy, a bench DMM with a fast logging rate could also do this."
},
{
"post_id": "",
"author": "BILLPOD",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 02, 2024, 01:27:26 pm",
"content": "Good Morning Ted123, Page 58 of the Users Manual explains how to use the Min/Max function. Also, logging voltage using the internal Micro SD card can allow youto take samples many times per second, or 1 per second by default. Page 54 of the manual will explain how to log data by just pushing the 'Mem' button. So, if you RTFM, all your questions will be answered. And welcome to the 121GW Club"
}
] |
2025-10-17T16:31:05.640193
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/121gw-multimeter-import-cost-euirl/
|
121GW Multimeter import cost EU/IRL - Page 1
|
[
{
"post_id": "",
"author": "snoozer",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 19, 2019, 12:55:58 pm",
"content": "Hello,I have bought a multimeter from Uni-T a few months back but I am not really happy with it. Looking around and watching the EEVblog YT channel it looks as if the 121GW would be a reasonably priced good choice within my budget. I am wondering if anyone from the EU or Ireland could advise me as to what extra cost I need to expect importing it to Europe/Ireland. Ideally I would love to hear from someone who purchased it. I hope its not a duplicate question, have not found anything on this in the forum.I also had a look around for bench top multimeters 2nd hand from Instrument dealers and Ebay but there is nothing reasonably priced and shipping to my place from Europe at this point in time that would make sense for me.Kind RegardsJan P."
},
{
"post_id": "",
"author": "Mr. Scram",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 19, 2019, 01:41:36 pm",
"content": "Quote from: snoozer on August 19, 2019, 12:55:58 pmYou could consider buying it from Simon at least until Brexit happens.https://simonselectronics.co.uk/product-category/eevblog/"
},
{
"post_id": "",
"author": "snoozer",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 19, 2019, 01:47:49 pm",
"content": "Hi,thanks for that link, I will take that into consideration.RegardsJan"
},
{
"post_id": "",
"author": "snoozer",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 19, 2019, 03:56:51 pm",
"content": "Yes, I think the above is my best option. I have spend the last few hours to find out what the rules are re import of such goods. Everything that is over 30 Euro I have to pay the 23% VAT, I knew that. The bad part is everything over 150 Euro (that includes shipping, handling etc) is liable to import tax/duty of 12% or 15%, was unable to find that out precisely. That makes the UK shop my best option. Just have to be quick....... one never knows what BJ has in mind ;-)I have tried to find out a way to mark a topic solved but I somehow can't find anything here or on the Simple Machines website.ThanksJan"
},
{
"post_id": "",
"author": "bitwelder",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 19, 2019, 09:27:05 pm",
"content": "Quote from: snoozer on August 19, 2019, 03:56:51 pmI don't think there is a specific option to mark a question solved, but you could e.g. edit the title of the first post with or or .Enjoy your 121GW!"
},
{
"post_id": "",
"author": "thinkfat",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 23, 2019, 07:58:06 pm",
"content": "I bought mine from Welectron. They ship throughout EU definitely.https://www.welectron.com/Gesendet von meinem Nokia 6.1 mit Tapatalk"
},
{
"post_id": "",
"author": "snoozer",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 28, 2019, 02:13:21 pm",
"content": "Hi,thanks for the links, I have it ordered with a nice Probe Master kit and carry case. Can't wait for it to arrive now.Have FuN!Jan P."
},
{
"post_id": "",
"author": "snoozer",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 09, 2019, 09:43:12 am",
"content": "I got the meter last week and I am all happy. The best thing was the Master Probe test leads, they are REALLY sexy...... So thanks for the suggestion re Welectron, happy to buy there again, very quick service !Next on the list is a Function or Waveform Generator........ not yet sure how to select what is right for me. Seems weird that the CN cheapies have 60MHz or there about and lower price range Siglent, Rigol and the like 10-30MHz. I guess I have not yet understood the basics.RegardsJan P."
},
{
"post_id": "",
"author": "AVGresponding",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 09, 2019, 05:59:57 pm",
"content": "If you're wanting decent gear you may be much better advised to buy high quality second hand, rather than going for cheap and new.Bargains are out there for persistent and patient people; I've spent maybe £500 recently rebuilding my test and repair lab after a two decade or so absence from the field (aside from minor projects), and for my outlay I've acquired a Fluke 8840A with ac-09 option (5.5 digit, 0.005% basic accuracy, £90 inc shipping), a fully optioned Tek TDS420A scope with 7 high quality probes (£100 shipped), a Black Star Jupiter sig gen (only 2MHz, but I used one in the 90s and like it, £45 shipped), a TTi 1906 (5.5 digit programmable DMM, 0.05% basic accuracy, £63 shipped), several other meters, a couple of logic analysers, and a couple of power supplies.Just got the Fluke back from the calibrators (free, I admit I got extra lucky there) and it hit 0.003% on the 2-20v dc range. No brand new Chinese gear is going to get anywhere close to that for less than several thousand quid.There's no substitute for quality, and that's where your sig gen price difference comes from. You're paying for better quality components and better design which equate to longer service life and better output signal quality."
},
{
"post_id": "",
"author": "PerranOak",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 15, 2019, 02:38:37 pm",
"content": "About the 121GW: do you not get firmware updates for free from Dave?I notice that an update can be purchased on Simon's site."
},
{
"post_id": "",
"author": "thinkfat",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 16, 2019, 07:20:01 pm",
"content": "Quote from: PerranOak on September 15, 2019, 02:38:37 pmUpdates are free. I just updated to version 2.00. Procedure is simple and painless.Gesendet von meinem Nokia 6.1 mit Tapatalk"
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 07:28:00 pm",
"content": "Quote from: PerranOak on September 15, 2019, 02:38:37 pmFirmware updates are free. Simon will just sell them to you pre-updated to the latest which saves you getting an SD card and doing it yourself. It would be useful if you don't care about logging and don't have a micro-SD card and reader around to do it yourself."
},
{
"post_id": "",
"author": "thinkfat",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 16, 2019, 07:47:09 pm",
"content": "Quote from: ejeffrey on September 16, 2019, 07:28:00 pmInterestingly, the unit I bought through Welectron had a micro SD card installed...Gesendet von meinem Nokia 6.1 mit Tapatalk"
}
] |
2025-10-17T18:03:35.532221
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/121gw-oddity/
|
121GW oddity - Page 1
|
[
{
"post_id": "",
"author": "bashie",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 31, 2023, 01:10:12 am",
"content": "I recently got my 121GW and while tinkering today I noticed something interesting:When I tried to measure an 220K SMD resistor (marked 224), the meter read 149.xxK. I tried multiple times, and if the 121GW was in the 500K range it would read ~150kOhms, but it read 0.219 MOhms correctly if set to the 5M range.My UNI-T meter read the resistance correctly in both the 600K and the 6M range."
},
{
"post_id": "",
"author": "bashie",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 31, 2023, 01:15:24 am",
"content": "I changed the batteries to 4 L91s yesterday. I drained them a bit to get the voltages lower, to ~1.63V, similar to the OCV of a fresh alkaline. The meter reported 6.4V.When I switched back to alkalines it now reads ~215k in the 500K rangeIt now reads 215k even with lithiums. What's going onUpdate: with a fresh pack of L91s it reads 150k on a 224 and 216k on another 224. Why though"
},
{
"post_id": "",
"author": "bashie",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 31, 2023, 01:21:10 am",
"content": "from the manual:> Lithium batteries have a higher voltage and may cause the device to malfunction.Are there any detailed explanations about this?"
},
{
"post_id": "",
"author": "bashie",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 31, 2023, 01:24:25 am",
"content": "It now reads ~149.7 and ~219 in 500k and 5m ranges respectively with 4 fresh alkalines@Dave ?"
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 31, 2023, 07:24:50 am",
"content": "The extra voltage from lithiums will not cause an accuracy problem. That's a red herring.Sorry, I know it's basic but I have to ask, you aren't touching the probes with your fingers are you?This fault is very odd."
},
{
"post_id": "",
"author": "bashie",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 31, 2023, 08:33:02 am",
"content": "No, definitely not. When I keep the probes in place (not touching) when it shows 150K, I can switch into the 5M range and it will show ~220K. Weird"
},
{
"post_id": "",
"author": "Chalcogenide",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "August 31, 2023, 08:42:33 am",
"content": "You are not measuring the resistance value while in circuit, right?"
},
{
"post_id": "",
"author": "armandine2",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 31, 2023, 09:01:14 am",
"content": "Try regular THT resistors, first thing I'd have done after the weird SMD readings ."
},
{
"post_id": "",
"author": "EEVblog",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 31, 2023, 10:17:39 am",
"content": "Quote from: Chalcogenide on August 31, 2023, 08:42:33 amThat was my next question."
}
] |
2025-10-17T16:49:09.223362
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/128-x-64-mystery-lcd-identify/
|
128 X 64 mystery LCD identify - Page 1
|
[
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 30, 2020, 04:47:47 pm",
"content": "Hello All,Here is the back story. This LCD module is from an Roland TD-11 drum brain. You can google it if needed. The schematic is NOT available, nor really is the part (maybe I'm just to cheap, or maybe I just like a good mystery?)The LCD was cracked, no longer functions, and I would like to find something that will work.Known details:1. The resolution is 128 x 64 (I counted the dots on a close picture of a working one)2. There are 12 pins going into the LCD module from the main board of the drum brain.3. The LCD module does NOT appear to be COG or OLED as I can't see any chips and there is a separate backlight (not part of the 12 pins mentioned on point \"2\"4. The LCD module can have its contrast adjusted, through a user setting in a menu. More about this later.5. LCD driving IC is ROLAND RBA02021ABG. This MCU is used in other Roland gear and appears to drive many other styles of LCDs.LCD / MAIN BOARD PINOUT, known details and the MYSTERY...When powered on and sitting in a nominal state.PIN 1. is sitting at 3.3Vdc with a \"negative\" pulse every second or so. I think it's negative because it appears below the scope trace in AC mode.PIN 2. is at 3.2Vdc with no pulses. I'm pretty sure this the LCD_RST line as it is 2.2k to ground and matches a known Roland RESET scheme.PIN 3. 3.3Vdc, has shorter pulses than PIN 1 but with the same 1 second interval. It is also the PIN that has activity when the unit is asked to adjust CONTRAST in the user menu. ( I know this by going through a \"blind\" procedure to adjust contrast step by step without the need to see the LCD)PIN 4. 3.3Vdc very similar to PIN 1. Longer pulses every second.PIN 5. is held low at .03 Vdc and pulses \"up\" to 3.3v every secondPIN 6. is 3.3Vdc. No pulses. It appears to be the VDC trace as it is thicker than the others AND connects to the D+3.3V linePIN 7. GNDPIN 8. Capacitor to PIN 9PIN 9. see abovePIN 10. Capacitor to PIN 11PIN 11 see abovePIN12. Capacitor and 4.7M in parallel to GNDSo, any guess as to what this is?SPI and charge pump capacitors??? If so, how to ID SO, CLK, CD, CS etc?"
},
{
"post_id": "",
"author": "DrG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 05:20:17 pm",
"content": "https://www.aliexpress.com/i/4000370015852.htmlMaybe."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 30, 2020, 05:45:06 pm",
"content": "Yeah... that's dang close if not it! How did you find that so fast!?!?!?PINs 6,7, 12 looks right for sure. The cap pins make sense.PIN 2 looks right as another schematic lists pin 2 as RESEST and has the same 2.2k to ground as this main board does."
},
{
"post_id": "",
"author": "DrG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 06:04:38 pm",
"content": "Quote from: mkiijam on October 30, 2020, 05:45:06 pmI'd like to say that it comes from years and years of accumulated knowledge, skills and experience, but really all I did was search for \"128 x 64 lcd 12 pin\". Yes, I have used similar a few times.Do yourself a favor though, show some close up pics of the LCD back (any numbers etc) and see if you can identify a controller. Maybe you can't do all that, but you can find plenty of interface examples, but there could be some timing issues."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 30, 2020, 06:59:35 pm",
"content": "Yeah.... There is no usable info on the LCD module.okay, so here is some progress.I hooked it up best I could to another SPI type OLED.https://www.amazon.com/HiLetgo-128x64-SSH1106-Display-Arduino/dp/B01N1LZT8LPIN 1 of my main board went to \"CS\" on the OLEDPIN 2 to \"RES\"PIN 3 to \"SDC\"PIN 4 to \"CLK\"PIN 5 to \"MOSI\"Then of course just VCC and GNDAND this is what I got when I powered it up.The \"STICK\" and \"TEMPO\" make sense as this is a drum module LCD, but the other stuff???"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 07:49:55 pm",
"content": "It looks like it could not handle the fast SPI clock or firmware tried to do some windowing commands that are not supported by this LCD.There is a number of very similar, but subtly different protocols/controllers. You can see that in a later part the firmware tried to draw a frame, but every other pixel is blank.Do you have any pictured of the broken display? Can you grab some SPI commands being sent using a logic analyzer? Especially the part after the initialization."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 30, 2020, 08:01:31 pm",
"content": "Here is a close up of the LCD working."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 08:08:47 pm",
"content": "So the dots may be normal, but at the very least the image is flipped. Which again, tracks well with differences in displays. They all have similar commands, but some configuration bits, like flipping are different.Having captures of the communication may help figure out the controller type."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 30, 2020, 08:24:23 pm",
"content": "Ahhh...Only a scope, no logic analyzer."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 08:32:29 pm",
"content": "It would be pretty hard to capture enough data with a scope.Any way, most commonly used controllers are SSD1306 and SH1106, which is almost a clone of SSD1306, but with minor differences. Specifically with the display RAM size and layout.So the easiest thing you can do is figure out the display controller in the display you bought and get the other one.And buying things fromhttps://www.buydisplay.com/is a way to ensure that you actually get the display with a controller you need."
},
{
"post_id": "",
"author": "DrG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 08:52:33 pm",
"content": "I'm am guessing (and it is only a guess) that it was an ST controller - something like an ST7567 or an earlier one consistent with the time that the Roland was made. I'm guessing because of the fit with the 12 pin interface. I know I could be wrong.It was probably not an SH1106. Also note that he never connected the A0 line. Timing problems? Sure all that stuff. But look, this \"needle in a haystack approach\" is likely not going to end well.@mkiijam I and now @ataradov have asked you about pics of the broken display, but it is as though you never heard us. Do you or do you not have the broken display - if you don't have it then at least we can stop asking about that part. If you do, please provide some pictures as that could, potentially provide important information. Also, clear pics of where the 12 pin connector attached to the main board - anything that might be helpful like that.If you don't have the display anymore, you have to research as much as you can to get some information about that display. Repairs of the unit, repairs of similar units and so on."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 30, 2020, 09:41:41 pm",
"content": "PIN 3 \"A0\" went to SDC"
},
{
"post_id": "",
"author": "DrG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 09:56:08 pm",
"content": "Quote from: mkiijam on October 30, 2020, 09:41:41 pmOk gotya SDC is like SD which is like A0. So, yes, you connected A0 and I was wrong to say that you had not connected A0.So, what does the other side of the the broken LCD look like? If it is completely encased and there are no numbers on the case, can you peel it off so we can see the board under the case. Edit: Stripping away the backlight if you can. Just looking for clues.Also, what is around where the 12 pin connector attaches to the main board. Is it possible to also take a picture of that? Edit: IOW where are those components caps and rs that you mentioned in your first post."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 09:59:38 pm",
"content": "I still think the only viable approach here is to just try multiple displays with different controllers.Or capture the initialization command sequence and match the used commands/registers to known controllers.Those displays rarely have useful markings on them."
},
{
"post_id": "",
"author": "DrG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 10:05:42 pm",
"content": "Quote from: ataradov on October 30, 2020, 09:59:38 pmYeah, well, I can't disagree with you, depending on how you want to define \"viable\" and if you have a number of different displays/controllers to try ESPECIALLY ones that have a 12-pin connector that seems to match his interface as he described in his first post.So, yes, if he had that display with the ST controller that I linked to in my first post, I would definitely say, \"try that\".Can't hurt to search for clues though. Especially since you damn well know that somewhere at Roland at some time was a service manual that identifies the LCD. What do they do, burn all the service manuals when they stop selling/supporting the product? I think it is only 8 years old - sheesh."
},
{
"post_id": "",
"author": "DrG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2020, 10:58:21 pm",
"content": "Quote from: ataradov on October 30, 2020, 09:59:38 pmJust curious - is the \"TSE8G0708FPC-A2-E\" the identifier for the LCD the way it is on this onehttps://www.romasterl.com/index.php?main_page=product_info&products_id=204219"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 12:10:08 am",
"content": "Quote from: DrG on October 30, 2020, 10:58:21 pmDoubt it. It is the identifier of the cable by itself.Quote from: DrG on October 30, 2020, 10:58:21 pmWhat makes you think it is a display identifier in this case? I mean it says 12864 as part of the name, at least. But is this the actual ordering number?Well, it looks like LX-12864B11 is the generic name for this type of display. But I see it with all sorts of connector style.I've looked at a few displays I have for which I know exact part number, and none of them have anything close to the part number printed on the cable or the display."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 12:15:43 am",
"content": "Quote from: mkiijam on October 30, 2020, 08:24:23 pmFX2LP (Saleae clone) or similar would be enough to capture the commands - and are cheap as chips.The fact that you're even getting something remotely sensible with that OLED suggests you are already in the right ballpark for identifying the controller command set. My guess is that it is a descendant of the classic command set made famous by the S6B0724/0708 and the like from Samsung.(I have done similar work in the past.)"
},
{
"post_id": "",
"author": "DrG",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 12:45:46 am",
"content": "OK, I'll leave it up to the experts."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 31, 2020, 05:46:23 pm",
"content": "Here is a portion of a schematic that uses the same Roland driver MCU.It uses some 18 pin LCD..."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 31, 2020, 05:49:23 pm",
"content": "Another picture with my jumper wires partially in the way.The top left ORANGE wire is PIN 1, then the GRAY is PIN 2.You can see the 4.7M and caps on PIN 12 etc.."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 06:29:10 pm",
"content": "This looks like a typical set of components for SSD1306. But 4.7 M for reference current resistor is a bit high.But realistically it van be any controller, again.If you really want to figure it out, get one of those cheapo logic analyzers and get the initialization commandshttps://www.ebay.com/itm/USB-Logic-Analyzer-Device-Set-Compatible-to-Saleae-24MHz-8CH-for-ARM-FPGA-M100/253841718379"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 31, 2020, 07:14:52 pm",
"content": "Okay, I think I will...Side question. Is the a COG LCD??? I can't see any \"chip\" on the glass... it looks completely transparent to me. I think I may not understand COG?"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 07:17:58 pm",
"content": "The controller is mounted on the glass. It is not etched on the glass itself.In your case the chip is sandwiched under the place where the cable is attached. You can actually see it on your picture, just a small part or bare silicon sticking out."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 31, 2020, 09:17:09 pm",
"content": "AH!It's all becoming clear now.So the MCU puts out some kind of language that the LCD controller then sends to the actual GLASS unit. So, if I can see the language then we can guess which imbedded chip(controller) we need?"
},
{
"post_id": "",
"author": "MLXXXp",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 09:23:59 pm",
"content": "Quote from: ataradov on October 30, 2020, 08:32:29 pmSSD1306 and SH1106 are for OLED displays. If the Roland has an LCD display then it won't be one of those controllers.It could have a similar instruction set but the init sequence would probably be different."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 09:24:53 pm",
"content": "Yes, those SPI pins carry a very specific protocol (a series of register writes). Just knowing what register addresses are used and what values are written is enough to compare against the known controller datasheets."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 31, 2020, 09:27:12 pm",
"content": "Quote from: ataradov on October 31, 2020, 09:24:53 pmWell, I got the logic analyzer on the way. I'll update when it gets in."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 09:27:22 pm",
"content": "Quote from: MLXXXp on October 31, 2020, 09:23:59 pmBut the display that was already tried and partially working is OLED, so the one in Roland should be also OLED.There is no way regular LCD initialization code would even remotely work for OLED.Also, there is no backlight voltage on the connector, so it is 100% OLED."
},
{
"post_id": "",
"author": "MLXXXp",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 09:38:09 pm",
"content": "Quote from: ataradov on October 31, 2020, 09:27:22 pmThe OP mentions a backlight and the photo inthis postappears to confirm that. An OLED wouldn't have a backlight. Also, the mention of a contrast control would further imply an LCD. The OLED displays have \"contrast\" commands but they're not very effective."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 31, 2020, 10:15:10 pm",
"content": "It uses a separate backlight on another two wire cable. The backlight can be dimmed in the user menu."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2020, 10:20:46 pm",
"content": "Quote from: ataradov on October 31, 2020, 09:27:22 pmThe OLED controller manufacturers realised that having a command set nearly identical to existing LCD controllers would decrease design-in effort, so they did. For example,SSD1306:0x = set column start address LSB1x = set column start address MSB20 xx = set memory addressing mode21 xx yy = set column address22 xx yy = set page address40~7f = set display start line81 xx = set contrasta0, a1 = segment output directiona4, a5 = normal, pixel test (all on)a6, a7 = normal/inverted modeae, af = display on, display offbx = set RAM page start addressc0, c8 = set COM output directione3 = nopS6B0724:0x = set column start address LSB1x = set column start address MSB20~27 regulator resistor select40~7f = set display start line81 xx = set reference voltage (contrast)a0, a1 = segment output directiona4, a5 = normal, pixel test (all on)a6, a7 = normal/inverted modeae, af = display on, display offbx = set RAM page start addressc0, c8 = set COM output directione2 = resete3 = nopThe former is the common OLED controller that's been discussed in this thread previously, the latter is an older LCD controller from the late 90s/early 2000s that doesn't offer windowing/scrolling capabilities. Another one similar to the latter is the Sitronix ST7565P."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 01, 2020, 05:16:31 pm",
"content": "So the obvious question is, Do I really have any hopes of finding an after market LCD screen that will work?"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 01, 2020, 06:28:52 pm",
"content": "Quote from: mkiijam on November 01, 2020, 05:16:31 pmI would say, yes you do. You may not find the exact physical form factor, but you should be able to find a display that works.I still don't see any evidence of an a actual backlight, so focus on OLED displays. And there are not too many types to try."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 01, 2020, 09:22:03 pm",
"content": "Here is the backlight"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 01, 2020, 10:54:31 pm",
"content": "Oh, ok. Then you should be looking for the actual LCDs, not OLED ones.The name of the common controller for that was already mentioned.Still, knowing the commands that are used will help clarify things. And the worst case scenario - you can just use a small MCU to act as a translation layer for an OLED display, since that already works more than it should."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 01, 2020, 11:11:49 pm",
"content": "Thanks to that picture, there's another part number that shows you can buy a replacement, but it is rather expensive:https://www.merktron.es/es/roland/5251-lcd-spd-sx-cmf2p0791-ec3700007r0.htmlIt also suggests the same part fits the TD-25.When you get your LA you can see the commands it sends, and that should narrow it down enough to find a replacement. My bet is still on ST7565/S6B0724."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 02, 2020, 04:13:53 pm",
"content": "Quote from: amyk on November 01, 2020, 11:11:49 pmYeah... the part is available from Roland as well... like $100 or so. Where is the fun in that?Okay, I've got the logic analyzer... NOW WHAT!?!? Just kidding (kinda) I'm jumping into the world of figuring out how to hook this up without any software or docs! YEA!"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 02, 2020, 04:44:00 pm",
"content": "Okay, I've recorded the logic signals coming from PINs 1-5....AND?"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 02, 2020, 04:47:45 pm",
"content": "First of all, in the Saleae software add an SPI decoder and make sure you can see bytes decoded without the errors.You need to record very specific parts, not just random signals. You need to catch very first commands it sends to the LCD after power up."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 02, 2020, 05:09:51 pm",
"content": "Quote from: ataradov on November 02, 2020, 04:47:45 pmI'm using PulseView.I have added the SPI decoder and it seems like it's capturing something. I captured when it first turned on. I also asked it to decode with ST7735, but there were errors.What is a ST7567? That Chinese LCD that seemed to have the same 12 pin functions says it uses that CHIP."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 02, 2020, 05:13:23 pm",
"content": "You have 1 MHz sampling rate selected. This is way too low. Select the highest it will go (24 MHz) and hope that the actual clock is slow enough to meaningfully capture it. You need to zoom in on a single byte and make sure that you see periodic clock.And then attach the actual capture file.ST7567 is the controller IC it can be used in 100s of different displays. But all those displays will have a compatible command set because of that."
},
{
"post_id": "",
"author": "madires",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 02, 2020, 05:34:15 pm",
"content": "Or possibly an ST7565 which is quite common. BTW, the ST7735 is meant for color displays."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 02, 2020, 05:39:10 pm",
"content": "Pulse view seems to glitch at 24MHzHere is a file at 12MHz"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 02, 2020, 06:13:26 pm",
"content": "Sometimes the capture looks like the real SPI, but occasionally there seems to be some strange noise.If you look at D1, which I assume was CS. You can see that for the first couple transfers it is fine and it aligned at 8 bits. But then just a few transfers in, it is just a random noise not aligned to anything. The data is also repeated on D3 trace.So double check your connections to the logic analyzer.But you are on the right path. You can start to see the commands being sent. Now you can start matching that to controller datasheets."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 02, 2020, 07:35:54 pm",
"content": "Connections look right.I don't see D1 and D3 as the same, but not sure what you mean."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 02, 2020, 07:38:12 pm",
"content": "Look at the chunk at +3172170us in your log. In this part the signals look corrupted.Do multiple captures and compare them .See if you get the same results each time."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 02, 2020, 08:07:06 pm",
"content": "This seems different.."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 02, 2020, 08:15:11 pm",
"content": "This one has issues with the CS on the second and third transfers (+2919594us and +2929596 us).Figure out what is wrong with your setup. CS must remain low for the whole duration of the clock.Just double checking. Do you have ground of the analyzer connected to the ground of the device?"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 02, 2020, 08:28:31 pm",
"content": "Quote from: ataradov on November 02, 2020, 08:15:11 pmOops...How about this one?"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 02, 2020, 08:49:22 pm",
"content": "This looks like something. Now you need to extract the command that are sent and match them against the datasheets.In this case you see the commands:1. 0xe22. 0x81 0x8f3. 0x244. 0xa0 0xc2 0x2e......You need to write down the rest of them.0xE2 is a Reset of aforementioned S6B0724. So this is a decent first candidate."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 03, 2020, 04:12:02 am",
"content": "It's definitely in the S6B0724 family --- that e2 for reset gives it away --- but not it nor ST7565/ST7567 either, because 81 xx sets the contrast and the majority of controllers only offer 5 or 6 bits of adjustment, whereas this one is setting it to 8f and that implies a full 8 bits. c2 also sets bit 1 while most others in that family use bit 3 of cx for COM scanning direction control and leave bit 1 undefined.I found one controller that matches the above, the UltraChip UC1601s, whose company slogan inthe datasheetproclaims \"The Coolest LCD Driver, Ever!!\"Others from UC like the UC1701 don't have 8 bits of contrast, so the '1601s is currently the best match. Note that this controller does have scrolling functionality, which the S6B0* and ST7565/7 lack.A good (but incomplete) comparison:https://github.com/olikraus/u8g2/blob/master/doc/controller_cmds.txt"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 04, 2020, 08:50:07 pm",
"content": "So any ideas where to find an LCD that uses this chip?"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 04, 2020, 08:56:29 pm",
"content": "You need to transcribe the commands first and see all the commands that are used.So far the commands are also compatible with ST7567, which is a more modern and widely available chip. It is likely to just work.There are plenty of suppliers of displays with that controller. I personally like BuyDisplay. Something like this may workhttps://www.buydisplay.com/1-54-inch-blue-128x64-graphic-lcd-display-module-spi-for-arduino-1But they have plenty of other options, pick whatever fits the size."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 05, 2020, 06:15:09 pm",
"content": "I suppose the ST7565 wont work?I see tons that use that chip..."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 05, 2020, 06:19:11 pm",
"content": "Well, you have not extracted the commands from the logic capture, so it is impossible to tell if it will work. If you do that, you could compare the commands against the datasheet.A few commands that we have here are the same."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 06, 2020, 12:53:35 am",
"content": "Neither the 7565, 7567, nor SH1106 OLED the OP tried without success has any scrolling/windowing feature (the SH1106 doesn't even have an e2 RESET command), so I suspect a 7565/7 LCD would probably show nearly the same results as the SH1106.But I haven't and won't go through the few hundred MB of serial capture data that was posted to read out the commands either, that's something OP needs to do."
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 06, 2020, 01:00:41 am",
"content": "Quote from: amyk on November 06, 2020, 12:53:35 amI will do whatever grunt work you guys say. At this point I haven't a clue of how to \"go through...\" the data. But, I will dig in somehow! Thank you all for the help so far, this has been very neat!"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 06, 2020, 01:04:14 am",
"content": "Quote from: mkiijam on November 06, 2020, 01:00:41 amDid you setup the protocol decoder in the logic analyzer? In your logs the first command that is sent is 0xE2. Do you see that value in your decodes? If so, you need to got though the rest of them and write down all the unique commands you see.For long transfers you only need to write down first 5-7 bytes,"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 06, 2020, 01:31:18 am",
"content": "Like this stuff from the \"MOSI Transfer\" lines?E281, 8F24A0, C2, 2EEBA4, A6, 89, AFF3, 3F, 00, 10, B0, 00, 00, 00,...00, 10, B02E, 24, A0, EB, 81, 8F, C2, 40, 85, 89, A4, A6, F1, 3F, F2, 00, F3, 3F, AF81, 8C"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 06, 2020, 01:38:07 am",
"content": "Yes, this. You basically need to find as many unique commands as you can.Then download the datasheets for all the mentioned controllers and see if the command makes sense.The datasheets mostly describe the commands in binary, so 0xE2 would be 1110 0010.In most cases only the first byte after the CS was asserted matters, but it also useful to check for each command if followup bytes and their count make sense."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 06, 2020, 03:43:52 am",
"content": "The majority of the data will be display (bitmap) data. Look at only the bytes where the CD line is low....and if the bytes you posted are all commands, it pretty much confirms that the controller is a UC1601:E2 - reset81, 8F - set Vbias (contrast) to 14324 - set temp compensation to 0 (default)A0 - set frame rate 80fpsC2 - SEG/column sequence inversion2E - set power control, defaultEB - set bias ratio 9A4 - disable all-on modeA6 - disable inverse display89 - set RAM address control defaultAF - enable displayF3, 3F - set partial display end = 6300 - column address LSB = 010 - column address MSB = 0B0 - page address = 0...40 - set scroll line 085 - partial display on89 - set RAM address control defaultA4 - disable all-on modeA6 - disable inverse displayF1, 3F - set COM end = 63F2, 00 - set partial display start = 0F3, 3F - set partial display end = 63AF - enable display81, 8C - set Vbias (contrast) to 140Bolded commands are not present on ST7565/7, and in particular Fx are \"do not use\" test commands. I can't find any other controller in that family with the F1/F2/F3 and of the right size (UltraChip has a few others of different sizes but the same set of commands.)"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 21, 2020, 12:10:20 am",
"content": "Well, just for fun, I tried the ST7567 and it didn't workU1601 is where it is at I suppose... no just to try to find one!"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 23, 2020, 03:50:57 pm",
"content": "Along with looking for a U1601 based LCD, are there any software based emulators or something? Like a USB into your computer that then translates the LCD signal into an image you can see?"
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 23, 2020, 06:38:04 pm",
"content": "I'm not aware of anything like that. It is really easier to just look at the command sent to the display and find the right controller."
},
{
"post_id": "",
"author": "MLXXXp",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 23, 2020, 08:01:38 pm",
"content": "Quote from: mkiijam on November 23, 2020, 03:50:57 pmYou could probably emulate the U1601 using a FPGA. This project emulates a SSD1306 to a VGA monitor but you could likely modify it for U1601 and output to whatever you like:https://github.com/uXeBoy/VGA1306"
},
{
"post_id": "",
"author": "mkiijam",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 24, 2020, 12:39:34 am",
"content": "Quote from: MLXXXp on November 23, 2020, 08:01:38 pmThat is very cool but way over my head.I hate this question, but I have looked. Am I missing something or is a LCD with the U1601 controller impossible to find?"
},
{
"post_id": "",
"author": "drussell",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 24, 2020, 01:26:39 am",
"content": "Quote from: mkiijam on November 23, 2020, 03:50:57 pmQuote from: ataradov on November 23, 2020, 06:38:04 pmWow, that could be a cool project, though... It would be a handy device, (well, software, really.)"
},
{
"post_id": "",
"author": "drussell",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 24, 2020, 01:43:17 am",
"content": "QuoteWhat physical size is this display, anyway?There is a 2.8\" on that buydisplay site that uses a UC1701, you would need to compare the datasheets to your commands to see if it matches because the commands aren't identical to the UC1601 but it does look like it is one of that family.https://www.buydisplay.com/blue-2-8-inch-128x64-display-serial-lcd-module-spi-with-touch-panelIt says \"touchpanel\" but that's an optional accessory...Edit:Oh, wait... that one's not the 12-pin style you're looking for..."
},
{
"post_id": "",
"author": "Lomax",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 29, 2020, 08:36:08 pm",
"content": "This looks pretty darn close, and uses the UC1601 controller:https://www.ebay.co.uk/itm/123192333083Try searching eBay \"including description\" for \"UC1601\" and you'll find more (and cheaper) examples.Thanks for an interesting thread btw, taught me a lot about identifying LCD drivers!"
},
{
"post_id": "",
"author": "yejing",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "August 25, 2022, 04:21:47 am",
"content": "This screen appears in aliexpressRoland TD-11 LCD Can search"
}
] |
2025-10-17T17:06:29.792631
| 71
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/129322-help-with-crappy-usb-isolator/
|
🤪 Help with Crappy USB Isolator - Page 1
|
[
{
"post_id": "",
"author": "Lord of nothing",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 26, 2019, 09:18:22 pm",
"content": "HiI got this:https://www.delock.de/produkte/S_62982/merkmale.htmlThe claim to be perfect for better measurement Results and so on...Now I opened up:Well the Case is just made out of Plastic with no shielding.What kind of component are the Blue Flat thinks? And what is there purpose?The Problem is there is power from the Laptop to the USB Device.Are the Black \"Box\" the Power Transfert?Sadly the Noise level are still the same so the idea is to desolder the think who transfer the power and use the Powerjack."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 26, 2019, 09:35:04 pm",
"content": "Quote from: Lord of nothing on June 26, 2019, 09:18:22 pmThose are ceramic capacitors.QuoteThis is not a problem but how USB works. It seems this device can both supply power from computer or optional external PSU if higher current is required.QuoteThis is isolated DC/DC converter.QuoteIs this noise level even related to USB? And what is the device to begin with? If it's cheap oscilloscope, you are unlikely to see any difference."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 26, 2019, 09:43:43 pm",
"content": "An interesting implementation.The \"blue flat things\" are a pair of Y caps, they appear to be in parallel, connecting the two USB grounds [EDIT: or at least shields] together. Unfortunately they will also couple high frequency ground noise.Yes, the black box is an isolated DC-DC converter. Unfortunately, if you bypass it and use the DC jack (9-30V) it will still be using the on-board SMPS (U4) to power the isolates side. Noise level will depend on quality of design.The 480Mbps claim is suspect. It looks as if they are using an ADUM4160 with the number ground off. If so, it is capable of USB2 Full speed (as they say in the description) but that is 12Mbps. It's USB2High Speedis 480Mbps. I am not aware of any single chip USB High speed solutions at the moment."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 26, 2019, 09:48:11 pm",
"content": "Quote from: Gyro on June 26, 2019, 09:43:43 pmThose are just usual 3kV rated capacitors, not Y safety capacitors. They might couple noise from computer but they also reduce noise from DC/DC converter. It does not seem they are connected in parallel. One of them is certainly coupling ground but other is not."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 26, 2019, 09:53:51 pm",
"content": "Quote from: wraper on June 26, 2019, 09:48:11 pmSure, I meant Y caps in the context of cheap high voltage isolation caps - Y caps are used in high volume, so cheap.EDIT: I can see the marking on one of the caps now, yes, 3kV Z5U, no agency markings - I need to get my eyesight checked!QuoteWell spotted, I missed the isolated pads, possibly one coupling the 5V rails as well then."
},
{
"post_id": "",
"author": "Lord of nothing",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "June 26, 2019, 09:56:27 pm",
"content": "THX for replay.QuoteSorry I forgott to tell its an SDR. I see when my Laptop is connect to the \"original\" Lenovo Powersupply a lot of noise.QuoteIs there an way to mod it to keep the noise away from the Laptop? Its from 2Mhz to at least 20Mhz (Range of my SDR with Up converter).QuoteI guess on both sides are Coils?QuoteThe SDR work with that. I dont know what the speed of the SDR is.I just need a clean signal."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 26, 2019, 10:04:19 pm",
"content": "Try removing black DC/DC converter and both blue capacitors. However it's not guaranteed to provide any improvements. You also could try using USB cables with ferrite chokes if not using them already (note that some cheap cables have fake ferrite rings co them which are actually molded plastic with nothing inside). You also could just take some ferrite ring and making a few turns of USB cable through it."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 26, 2019, 10:07:05 pm",
"content": "Agreed, removing the Isolated DC-DC converter and two blue caps,mightyield the quieter result. It depends though whether the DC-DC converter is noisier than the buck regulator for the external power jack or not.Do a search for the ADuM4160 / ADUM3160 Eval board datasheet for a bit more info."
},
{
"post_id": "",
"author": "HB9EVI",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 27, 2019, 12:03:09 am",
"content": "Aside from the RF issues my guess is that it doesn't support hispeed usb (480mbps) - so no way to run SDR data over it; they are just not working with 12mbps onlyeasier to achieve is galvanic separation between antenna and SDR, at least if it's for reception only..."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 27, 2019, 08:07:28 am",
"content": "OP's link does sayQuotePerhaps it'sthough. Test it with a USB 2.0 pendrive, I ugess.If you are already modding it, no problem with removing and bypassing the internal step-down converter. The external PSU will need to be exactly 5V then.That's if the goal is noise. If it's about protection from lightning strikes to the antenna, it may be cheaper to use a sacrificial single board computer like RasPi to run the acquisition process and transfer captured data over WiFi. But I guess you have already bought that device, so..."
}
] |
2025-10-17T18:07:50.763009
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12ac-to-12vdc/
|
12AC to 12vdc - Page 1
|
[
{
"post_id": "",
"author": "CharlesTT",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 25, 2020, 04:31:11 pm",
"content": "Hi guys I am having a bit of a problem trying to get an led light to work. It is a 240v led light that I have replaced the driver with a 12v model that outputs 6v for the leds. The Waterproof transformer I am using ( it is fit an outside light ) outputs in AC and i'd rather not replace it as it is driving all of the other lights just fine.Is there a way I can convert its output to DC? Would I have to use a bridge rectifier and if so could you suggest one? or an alternative driver..CheersCharles"
},
{
"post_id": "",
"author": "WattsThat",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 26, 2020, 01:39:02 am",
"content": "A 12 volt ac transformer will result in approximately 17 volts dc when rectified and filtered. A full wave bridge and appropriately sized capacitor followed by a switching buck regulator module is one way to achieve your goal. But, by the time you’re done with sourcing, fitting and mounting the additional parts required, it’s probably easier to purchase a dc output wall wort to power the led’s.Do you know what current at 12vdc is required for the led’s? Can they be driven with a constant voltage? An led driver is usually a constant current device.That’s the missing information at present for a more informed answer."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2020, 03:06:04 pm",
"content": "What sort of LEDs are they?The easiest way is to replace the LED or driver with one which is designed for 12VAC."
}
] |
2025-10-17T17:57:01.580471
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-10a-dc-dc-to-5v-circuit/
|
12V 10A DC-DC to 5V circuit - Page 1
|
[
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 03, 2023, 01:30:17 am",
"content": "Need to step down from a 12V Car battery to Arduino?I found one but it using large components ( attached ).I wonder if LM2596 board will do the job safely, but can't find a circuit for it.Thanks"
},
{
"post_id": "",
"author": "JustMeHere",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 04:09:03 am",
"content": "Cars have a very \"toxic\" power environment. They are nominally 14.4 volts while running. They can drop to 9 volts when starting. There can be large load dumps causing 120 volt spikes."
},
{
"post_id": "",
"author": "Swainster",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 05:04:16 am",
"content": "Car battery to 5V @10A? Your linear circuit example (at least the 3D modeled part) will definitely burn up as it will be dissipating almost 100W when the car is running. Those pass transistors need to bolted to a big ol' heatsink. Agreed that using a buck regulator is much better, however LM2596 is only specc'd for 3A."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 06:46:37 am",
"content": "I knew someone would mention the mythical load dump. Well technically it's not a myth, but I've never seen it happen and the vast majority of USB chargers and other devices that plug into a lighter socket will smoke if it happens. If your car was made within the last 40 years or so it is extremely unlikely, load dump protection is something you put on critical hardware like the ECU though even many of those lack it. For an auduino don't even worry about it. Modern car electrical systems are not nearly as hostile as a lot of people think, those warnings are from the era of crude electromechanical voltage regulators."
},
{
"post_id": "",
"author": "Eraldo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 07:20:40 am",
"content": "What do you need to power with the 5 volt? If just the arduino and some sensors then a regular 5v linear regulator can handle it.If you want a lot of power then just buy a powerful buck converter with high current capabilities (depends on your needs). They are also constant voltage devices so no need to worry about the battery voltage."
},
{
"post_id": "",
"author": "JustMeHere",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 01:59:17 pm",
"content": "Quote from: james_s on April 03, 2023, 06:46:37 amAll it takes is a loose battery cable. And that's what was probably making the computers reset in my car the other day. Had to do a quick repair the other night."
},
{
"post_id": "",
"author": "JustMeHere",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 02:03:55 pm",
"content": "Here's a good app note:https://www.ti.com/lit/snva681"
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 03, 2023, 09:03:32 pm",
"content": "I did research on LM2596 as I don't need a lot of output power, 3A is sufficient. It will be actually powered MEGA2560. So I draw the attached circuit based on the LM2596 datasheet. I don't need an adjusted regulator. And yes the car ( it is actually for the motorcycle ) can supply 14V. So it must sustain that.As far as the >100V spikes on the bike shut down. Is there anything I can add to protect it? - not sure if the flyback is for. The are only for reverse current right?Can you guys have a look at the circuit, please? I added a 5V fuse (F3) and would like to add a fuse (F4) for 12V, no idea where to put it. Can you help? - unless this circuit and components are trash, please tell me that as well.Big thanksCheers."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 09:12:24 pm",
"content": "I've used the LM2596 and it's a good part, easy to use and works really well. Beware the Chinese modules you can get on ebay, they actually work pretty well but they are NOT real LM2596, the frequency they operate at is completely different."
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 09:16:56 pm",
"content": "The 680uF capacitor is configured wrong. Negative side of cap should be grounded. The way it is now will block DC voltage.Feedback must be connected to output.https://www.ti.com/lit/ds/symlink/lm2596.pdfPage 1"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 09:20:28 pm",
"content": "That's a very weird way of drawing a buck converter too, I would not even have recognized what I was looking at without closer investigation. Draw it the way it is on the datasheet and it will be a lot more clear.Also the part shown in your drawing is the -ADJ (adjustable) variant which needs an additional pair of resistors to set the output voltage, without that you will have a 1.2V power supply."
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 09:25:12 pm",
"content": "Quote from: james_s on April 03, 2023, 09:20:28 pmNot really. Its a way to emphasize that connections need to to be kept as close to the regulator as possible."
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 03, 2023, 09:39:09 pm",
"content": "680 Cap, I screwed this one up. Thank you, corrected.Also changed LM to SX-3.3 from -ADJ. Is this correct ?I redrew the circuit, based on the new pinout locations.6th pin, is it just a heatsink?What about the fuse for 12V, if I need it at all. And additional spike protection, can you advise?Thank you so much"
},
{
"post_id": "",
"author": "Bud",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 10:22:04 pm",
"content": "3.3 means it is a 3.3V part. If you need 5V you use the part with index 5.0, or ADJ with a resistor divider, see the datasheet for the adjustable regulator design procedure."
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2023, 11:18:07 pm",
"content": "Quote from: misiek303 on April 03, 2023, 09:39:09 pmYou can put a fuse on the input side if you like but won't be necessary since you have one on the load side.Arduino is usually supplied with 500mA from a USB so no more than a 500mA fuse would be required.Over voltage lock out could be added but really won't be necessary. The 680uF capacitor is probably enough.Main thing is to try to keep the coil orientated far enough away from the chip to keep EMI from the coil magnetic field interfering with the chip. A board layout is presented on page 32 of data sheet."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2023, 01:12:39 am",
"content": "A fuse on the input side is advisable for an automotive application, unless you know the circuit feeding it is fused at a low enough value that the fuse will fail before something catches fire. Under normal circumstances you can rely on the regulator to protect against faults, but if the fault is with the regulator IC itself or the input filter capacitor then the protection features of the IC won't help."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2023, 05:57:15 am",
"content": "Not much fun in that."
},
{
"post_id": "",
"author": "Eraldo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 04, 2023, 02:04:48 pm",
"content": "I'm failing to understand op. Does he just want stable 5v 3A or does he just want to try and build his own buck converter.Just wanna know if what he needs is functionality or a project to do in his free time. If functionality is what you need, just buy a buck converter off amazon or any other store with buck converters. In aliexpress you can get 8A ones for less than 5 euros.On the other hand if you just want to build your own then you will have to delay the main project where you seem to want to work on (which requires 5v 3A). Or, as Edavid said, just buy a capable car charger (which are buck converters in disguise) and youre done.You gotta be more specific with your needs op."
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 04, 2023, 02:20:43 pm",
"content": "Quote from: Eraldo on April 04, 2023, 02:04:48 pmI am designing a board for my motorcycle that controls all lights and starts the bike. I want it all on one board. The board will use Mega2560 which will control ProFets. I will connect it to the 12V motorcycle battery to power it up, therefore the DC-DC buck converter implementation that I want to put on the board. Is this DC-DC buck overkill or should I look for a different approach?, like using an optocoupler with resistors?I started the other post to add one more feature. I need to sense another 12V input that comes from the Ignition Key[] GND[] 12V Battery constant power[] 12V Ignition KeySomebody responded that an optocoupler is sufficient. It must just sense the 12V ignition Key and trigger an IO on Mega to wake it up. So if I can do that safely with Optocoupler, why I can't use another one to power it up?Does this make sense?Thank you so much for helping out?"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2023, 05:04:44 pm",
"content": "An optocoupler is an isolated switch, you power the LED on one side and it causes the transistor to switch on and conduct on the other side. You can't power something through an optocoupler, each side needs its own power source."
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 04, 2023, 05:33:57 pm",
"content": "Can optocoupler share the GND with input and output ?"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2023, 05:36:40 pm",
"content": "Sure, the two sides are totally isolated, they can share anything that doesn't need to be isolated. They're essentially a relay, except optical rather than mechanical."
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 05, 2023, 02:15:22 am",
"content": "I did research and draw this. It is an inverted connection for the optocoupler. I wonder if bc817 should do it as well.As far as I understood, the inverted is pull-down and the non-inverted is the pull-up?I don't know why the attached drawing is inverted actually, I don't understand the physics here yet.Regardless, is this circuit correct?"
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 05, 2023, 04:12:52 pm",
"content": "ok, regardless.If I have input IO with PULL-UP enabled, Do I need to pull it down to change the IO state?if so. Do I need an inverted or non-inverted option and what does it actually mean, I get different information when I read things and this is so confusing.Thanks"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2023, 05:10:10 pm",
"content": "I'm not sure I understand what you're asking. Input pull-up is used for active low inputs, ie the default state is high and then you assert it by pulling it low. This is the most common way buttons and such are interfaced to a microcontroller."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2023, 05:11:51 pm",
"content": "Quote from: misiek303 on April 05, 2023, 02:15:22 amThat can't possibly work, you've got +5V connected directly to the IO pin so that pin is hardwired high and there is no way the optocoupler can do anything with it."
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 05, 2023, 05:36:13 pm",
"content": "Quote from: james_s on April 05, 2023, 05:10:10 pmThis is exactly what I want to achieve, what you just said. Is this circuit more like it?If not can you draw something for me?Also is this circuit inverted or non-inverted. I still understand this."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2023, 05:41:55 pm",
"content": "No that's still not right, I'm beginning to feel like you are just randomly guessing how to connect things together. Have you read The Art of Electronics or taken any of the EE courses on Khan Academy? If you want to design circuits there is really no way around learning the basics, trust me on this, you will spend an enormous amount of time and frustration trying to figure things out if you have gaping holes in your understanding of the basics. Hang on, I'll draw this up for you."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2023, 05:49:33 pm",
"content": "This is how it should be connected. You probably don't need the pullup resistor if you have the internal pullup enabled on the IO pin but in (electrically) noisy environments it can be helpful to have a stronger pullup."
},
{
"post_id": "",
"author": "misiek303",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 05, 2023, 06:26:56 pm",
"content": "Quote from: james_s on April 05, 2023, 05:41:55 pmYou feel it correctly. I have no clue what I am doing, therefor I am here in the beginner's group, hehe. I probably should start from the classes. I really want to accomplish something quickly, but it is overwhelming so I wonder if I should stop.Thanks for the drawing. I appreciate it.If you don't mind I have more questions.If the IO is pulled up internally, and if you want to change the pin state you short it to the GND, like a push button. So why in my circuit do I need 5V at all?"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2023, 06:39:30 pm",
"content": "You really should spend at least a few days going over the basics, you don't need to take a complete EE degree course but pick up the fundamentals. Basic circuit concepts, Ohms law, Kirchoff's law, series and parallel circuits, etc.You don't. 5V powers the microcontroller, that's the only place you need it, the internal pullup will pull the pin up to 5V with an internal resistor so to assert that input you short it to ground. If you use an external pullup you will need 5V for that too."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2023, 09:56:56 pm",
"content": "Has anyone noticed the circuit attached to the original post will only work up to 1A? Q1 and Q2 will never turn on. Their bases should be tied to the input of the 7805 and R1 & R2 should be an ohm, not 1k. F1 is not needed because the regulator will limit the current. F2 should be on the supply side to the entire regulator to protect the cable in case the it fails short circuit."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2023, 10:02:09 pm",
"content": "I didn't even look at it to be honest, in this day and age there are few reasons to go with a 78xx regulator and external pass transistor, it's so easy to build a working buck converter now that it makes sense to do so in most cases where you need more than a couple hundred mA or so. The only time I'd consider linear is if I needed very clean power or some other specific need."
}
] |
2025-10-17T16:56:30.090371
| 33
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-5-amps-vs-19v-3-amps/
|
12V 5 amps vs 19v 3 amps? - Page 1
|
[
{
"post_id": "",
"author": "DW1961",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 08, 2020, 12:28:40 am",
"content": "My laptop converter says output is 19V at 3 amps.I have a light strip converter that says 12v 5 amps.That's roughly the same watts, but my question is why 19V instead of 12v for the laptop converter?"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 08, 2020, 12:39:37 am",
"content": "Why you did not ask about why not 120V 0.5A? The question is about as meaningful. As of why you would not use 12V for a laptop, 3A current requires thinner wires and with 12V input you cannot use buck converter to charge 3S lithium battery (12.3V) they usually use."
},
{
"post_id": "",
"author": "DW1961",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 08, 2020, 12:57:53 am",
"content": "Well, I'm sorry it had no meaning. I thought this was a beginners forum. Sorry for the inconvenience."
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 01:40:25 am",
"content": "I would assume for a laptop power supply that it needs the extra voltage to charge the batteries and to overcome the regulator drop-out voltage.In order to charge a battery, the charge voltage needs to be higher than the battery voltage to have current flow into the battery.For a regulator, you need a higher voltage to allow for voltage loss through the active components."
},
{
"post_id": "",
"author": "DW1961",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 08, 2020, 03:01:07 am",
"content": "Quote from: MarkF on July 08, 2020, 01:40:25 amVery interesting. Thank you. Can you give me an example of regulators and active components that require 12V and how voltage loss interacts?Thanks so much."
},
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 03:08:21 am",
"content": "Quote from: DW1961 on July 08, 2020, 12:28:40 amThis in no doubt an over-simplification. But using the simple case makes the answer to your question is easier to understand. So, here goes:Typical laptops with removable Lithium Ion batteries would use 3, 6, or 9 batteries (typically 18650's) arranged in 1, 2, or 3 column(s) of 3 batteries back to back. The \"3 batteries back to back\" is the same as saying 3 batteries in series. The 1p3S (1 column, 3 in a series/row to make a column) is the typical \"light\" pack, 2p3S is the typical standard pack, and 3p3S is the typical extended battery pack arrangements.In that \"3S\" arrangement,three 4.2 volt batteries in series would appears to the world as a single battery with 4.2V*3=12.6V. A 12 volt source will not be high enough to charge a 12.6 volt battery. Charger's electronics themselves would have somevoltage dropand those electronics sit in between the power-converter and the batteries. So, thetotal voltage requirements is 12.6V plus the voltage required by the charging electronics. Now you can see 12V is a non-starter -- even without charging electronics, you need 12.6V for the batteries alone.Say you go up to a 16V power converter, you would have 16V-12.6V=3.4V, that is 3.4V head room for the charging electronics. 3.3V components are common, but that leaves a mere 0.1V margin. For example, you may have a 16V power converter running just a little under like a very small 0.2V under. 0.2V is small, but you are out of luck just the same -- you are now below requirement giving just 3.2V for your 3.3V components. So, you need lower voltage components (lower than 3.3V) for your charging electronics - which limits your choice of components and probably increase cost. My early (1998-2001) Sony and Fujitsu laptops use 16V power bricks. A 19V design gives more head room. At 19V, the charging electronic have a 6.4V margin to work with.Some high-capacity Lithium Ion batteries has nominal voltage at 4.35V instead of 4.2V. So 3S the 4.35V cells would need 13.05V for charging (instead of 12.6V for charging the 4.2V cells). A 16V laptop brick would have only 2.95V head room for the charging electronics. The extra 3V more in headroom a 19V power-converter give would probably be welcomed in those cases.Now stuff that make it more complicated:Typically, laptop charging circuitry will have additional electronics to \"balance\" the cells so that all the cells are charged to equal degree. Some would have the intelligence to \"lock out\" bad cells while keeping good cells in service.The arrangements is not always 3 series than parallel these columns. They may also be 3 connected in parallel first which make a composite single battery with 3x the capacity (instead of 3x the voltage as in series), than serialize those 3 \"composite battery\" in a rows of 3. So, different designs are used.Typically, the first thing after the power converter is a voltage regulator first - to ensure that the power source is not giving out something silly. The rest of the charging electronics sits after the voltage regulator. So, there is yet more voltage drop...I hope this explanation make sense to you and helps you.EDIT: I know this reply has already been seen and quoted, but this stupid single character typo really bugs me and I have to correct it.Now stuff that make is more complicated:corrected the \"is\" to \"it\" so it now readsNow stuff that make it more complicated:"
},
{
"post_id": "",
"author": "DW1961",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 08, 2020, 03:30:27 am",
"content": "Quote from: Rick Law on July 08, 2020, 03:08:21 amHell yeah! It makes a lot of sense. I have some rudimentary understanding of how voltage drop and over head works, and how stacking batteries in a series increases voltage (such as using 3 AA batteries in a series creates a 4.5V battery, so your explanations are extremely helpful.Aside from the battery needing more than 12V, could using more voltage also be part of having to run the screen, CPU, Ram, etc., also?"
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 08, 2020, 03:51:30 am",
"content": "Quote from: DW1961 on July 08, 2020, 03:30:27 amNot really. The rest of the laptop will be designed to run off the battery - and CPU, RAM run on much lower voltages.The screen, however, could be a different story, depending on what is used for the backlighting (for your typical LCD panel)."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 07:03:27 am",
"content": "Using a higher voltage is advantageous as the current will be lower for the same amount of power. Current is what causes heating in wires and semiconductors and heating is wasted energy. A related effect of this is that a buck regulator to drop a higher voltage down is more efficient than a boost regulator that raises a lower voltage up because the current in the switching device and inductor are lower in the former than the latter. Similarly the power grid that supplies your house uses very high voltage to transmit the power over long distances, often as high as 120,000V and then substations and distribution transformers step down the voltage to lower levels, eventually down to the 240V that comes into the house. The high voltage is used because it can send much more power over the same size wire with the same losses from current heating up the wires. Similarly a small shaft spinning at high speed can transfer the same amount of mechanical energy that would require a much larger shaft turning at a slow speed because torque is what determines the mechanical strength of shaft required and power is a product of torque and speed.In the laptop it's more efficient to drop 19v down to whatever the battery voltage is sitting at rather than boosting a lower voltage up to a level sufficient to charge the battery. The rest of the circuitry in the laptop will run on 3.3V and various lower voltages."
},
{
"post_id": "",
"author": "DW1961",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "July 08, 2020, 05:30:37 pm",
"content": "Quote from: james_s on July 08, 2020, 07:03:27 amAwesome explanation and analogy. Thanks."
},
{
"post_id": "",
"author": "Nerull",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 08:17:20 pm",
"content": "Most modern USB charging standards negotiate a higher voltage for similar reasons - you can deliver more power over the same wire with higher voltage. USB-PD can deliver up to 100W by operating at 20V/5A. Delivering the same power at 5V would require 20A. I don't think you want to plug your laptop in with 12 gauge wires.OnePlus' Dash/Warp charging is an exception, pushing high currents at 5V, and requires special cables built to handle the higher current."
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 08, 2020, 09:37:58 pm",
"content": "Internally, laptops have pretty high-current 5V (used for USB and storage media) and 3.3V (lot of internal logic) buses, plus lower voltages for the processor and associated circuitry. These are all derived from the battery voltage using buck converters.If we assume the battery pack charging circuit, including its internal voltage drop, requires say 14.7 V, why not use a 15 V charger, then?The nominal voltage of the charger output is not exact. At minimum, 5% variation is allowed (even with USB 5V), and 10% is more typical. So, if you have a 19V charger, its output could be anything between 17.1V and 20.9V, and still be within spec.Around 19V seems to be a pretty good compromise between power delivery and ease of conversion to lower voltages using very small circuitry. If you used a higher voltage to charge, you'd need better isolation between tracks; and there really isn't any room to spare in a laptop. (Louis Rossmann has mentioned in his Apple repair videos how some Apple laptops have a +20V backlight line next to a logic level signal in the display connector, and they tends to blow whenever a little moisture or gunk gets in, bridging the contacts.)Desktop PCs have additionally a +12V line for peripherals, a -12V line for serial port, and a +5V standby. In datacenters, an entire rack can have a common +48VDC 300A voltage source, which is individually stepped down to +12V, +5V, and +3.3V using small DC-DC converters inside each rack-mount chassis.There are also small DC-DC power supplies like PicoPSU, that act like desktop PC power supplies, but at a lower power level (150W typical maximum).As an example, M3-ATX can be powered from 6 to 24 V, and it'll provide up to 6A on the 5V and 3.3V lines, and up to 4A on the 12V line. These are often used for automotive PCs."
},
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 04:27:29 am",
"content": "Quote from: Brumby on July 08, 2020, 03:51:30 amDW1961,Your question in the quote of the quoted reply is masterfully answered byBrumbyalready. But seeing your question, I think you may be missing one trick up your sleeve. If I may be so bold, allow me to bring that trick to your attention.You seem to think that to power something, we need to drop the voltage -- not necessarily so.-----------------------------------Case 1:-----------------------------------When you connect things in series, each connected thing will cause a voltage drop. In this case, you can think of powering those things with voltage drop. Say you have two incandescent bulbs, bulb-1 and bulb-2, connected in series to the power source.Source+ -- Bulb1 -- Bulb2 -- Source-Voltage will drop after bulb-1 and then drop again after bulb-2, so the voltage is split between them. The Current flowing through bulb1 must also flow through bulb2 before it returns to the \"negative/ground\" terminal of the power source, so the current through both is the same current.Bulb1 and Bulb2 splitting the voltage meansV1+V2=Vsource;and V1 can be different than V2 if the bulbs are different in power consumption.They have the same current meansI1=I2=Isource, or simply, I1=I2=ISo bulb1 and bulb2 split the voltage between them, but has the same current.Power = Voltage * Current; or more commonly stated as: P=V*I, or W=V*I. Some use W because Watt starts with W. So:W1=V1*IW2=V2*I-----------------------------------Case 2:-----------------------------------You can connect them in parallel. In parallel is both bulbs connects directly to the power source.Source +/ \\Bulb1 Bulb2\\ /Source -In this case, both get the full voltage but they each have their own current. What Current flows through bulb1 has nothing to do with what current flows through bulb2. The current provided by the source is split between them.They both are directly connected to the source so:V1=VsourceV2=Vsourceso, V1=V2=VsourceThey split the total current:Isource = I1 + I2and I1 and I2 may be different if the bulbs are different in power consumption.So bulb1 and bulb2 split the current between them, but has the same voltage.W1=V*I1W2=V*I2-----------------------------------Summary:-----------------------------------In case 1 (series) youadd more voltage to power more thingsconnected in series but keeping current the same.In case 2 (parallel) youadd more current to power more thingsin parallel but keeping voltage the same.EDIT: Minor wording change to make it easier to read"
},
{
"post_id": "",
"author": "dcbrown73",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 09, 2020, 01:52:25 pm",
"content": "Great explanation guys!"
}
] |
2025-10-17T17:46:39.103222
| 14
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-5a-ish-step-up/
|
12v 5A ish step-up regulator - Page 1
|
[
{
"post_id": "",
"author": "TheBekker",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 24, 2016, 12:51:13 am",
"content": "HiI'm working on a hobby project and its powered by a 7,4v lipo, but for some motors i need 12v.So im looking to make a simple boost converter, but cant really find a appropriate regulator for it.Can anyone recommend a regulator that can boost my 7,4v to 12v at 4-5A.Tried googling for some, and looked at the LM1084IT-12, but not sure if that actually can step up? or if its only down?Thanks in advance"
},
{
"post_id": "",
"author": "Marco",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 24, 2016, 02:17:43 am",
"content": "Literally hundreds of external switch converter ICs which can do that. Just search for boost on digikey and select the switching controllers category.Or buya module."
},
{
"post_id": "",
"author": "Audioguru",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 24, 2016, 02:27:07 am",
"content": "The 2-cells Li-Po battery voltage will drop to 6.4V as it discharges, then if the efficiency of the boost circuit is 80% and it must produce 12V at 5A (60W) then the battery must produce 75W which at 6.4V is a current of 75W/6.4V= 11.72A. Can the Li-Po produce such a high current continuously without catching on fire?"
},
{
"post_id": "",
"author": "Towz",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "September 24, 2016, 02:35:37 am",
"content": "The LM1084 is a linear low dropout regulator, this it need a supply higher than the desired output. You need a boost (or flyback) converter like the LM2585-12 or similar, you might even whip out your own converter with a low end micro or even just opamps. Lots of ways to do it."
}
] |
2025-10-17T19:11:30.174267
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-a-atx-psu-bench-psu/
|
-12V A - ATX PSU Bench PSU - Page 1
|
[
{
"post_id": "",
"author": "kr15_uk",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 18, 2016, 03:28:18 pm",
"content": "Ladies and gents,I've built ATX Bench PSU some time ago, all good, but never had a chance to play with -12V or soNow I'm working on one small project where I'll finally need my 24V out of +12V and -12VBut... I'm a bit lost with AMP rating for this combination.+12V1 is rated for 15A max but -12V 0.5ASoooo.... My 24V in theory will be ??A... And I'm stuck here...Thanks.Kris M"
},
{
"post_id": "",
"author": "TheAmmoniacal",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "November 18, 2016, 04:12:28 pm",
"content": "CORRECTION: you're limited to 0.5 A because the current has to go through both rails (and thus you will be limited to the rail with the lowest rating)."
},
{
"post_id": "",
"author": "kr15_uk",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 18, 2016, 04:30:06 pm",
"content": "Thanks for the reply.Do you mind to share how you've calculated this so I don't bug people next time when I get something similar?!Like next possible option +5V 16A and -12V 0.5AI've tried to figure it out myself but none of the options were even close to 967mA...Thanks.Kris"
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 18, 2016, 04:51:05 pm",
"content": "I assume you intend to connect your projects +V to the supply +12V and -V to the supply -12V. The current out of the +12V must equal the current into the -12V (i.e. You're limited to 0.5A).I don't recommend doing this as your final solution. Your project will be referenced to -12V. Therefore, your project MUST be isolated from ground to prevent a short of your power supply."
},
{
"post_id": "",
"author": "kr15_uk",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 18, 2016, 05:02:13 pm",
"content": "Thanks Mark.0.5A makes more sense to me.24V is only for testing. If I'll find that 24V is way to go then I'll get proper bench PSU.Thanks."
},
{
"post_id": "",
"author": "raspberrypi",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 18, 2016, 11:19:11 pm",
"content": "The only way I know of is to read the label on the side of it. To generate the -12 volts requires dedicated circuitry that they don't beef up like the +12 because computer mother boards don't use alot of - voltage. I built one ofthose and was all excited to play with the negative voltage until I realized it was such little current. A crude way is to count how many wires come out for that voltage, lots of wires are to carry lots of current."
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 18, 2016, 11:19:49 pm",
"content": "Quote from: kr15_uk on November 18, 2016, 05:02:13 pmCareful with scope probes during testing. That ground clip on the probe WILL short your ATX supply."
}
] |
2025-10-17T19:08:18.308923
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-a23-battery-for-a-mcu/
|
12V A23 battery for a MCU. - Page 1
|
[
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 10:16:06 am",
"content": "Hi!I'm using a Gigadevice GD32VF103 MCU, with a small LCD, 3 sensors, and 3 LEDs. Is it fair to say that a small battery like a 12V A23 battery will only last a few hours with this setup? I've seen the datasheets and this seems to be the case. It's not possible to try on my own at this moment so I'm asking you guys. Edit: the sensor measurements, the LCD, and the LEDs are updated once per second.Cheers"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 10:42:52 am",
"content": "Since you would enable sleep mode on the MCU this is really going to be decided by how much current the LED and LCD are drawing.What is the total average LCD+LED current?There is a wide range of current draw from LCD types depending on if they are color and have a backlight or not.But yeah, couple of hours at like 10mA, and you will likely be wasting a reasonable percentage of the battery energy because you have too much voltage and have to burn off some of it as heat in linear regs.I assume you want to use a 12V battery because your LCD needs 9/12V ?But you'd probably be better off with a 1.5/3V battery and a boost circuit if the 9/12V is very low current.Just don't use CR2032's they are terrible for continuous current draw above 1mA"
},
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 10:57:58 am",
"content": "Thanks, yeah I'm inclined to agree. I will use a 9V battery with 550 mah, instead, like a 9V 6LR61 with 550 mah. Maybe it will last around 12 hours, then. The maximum load of the setup is around 2,5 W, and the minimum is around a tenth of that."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 11:27:41 am",
"content": "A23 batteries are internally a stack of eight tiny LR932 alkaline button cells with a nominal capacity of around 56mAH. Due to its smaller size and all the wasted internal space due to the stack of button cells construction, its only good for about 40% of the energy of a single Alkaline AAA. Your suspicions are correct - its a lousy choice for a powering a 32 bit MCU that isn't in a deep power saving mode nearly all the time, let alone lighting LEDs for any significant length of time.I assume you are aware that end-of-life the 6LR61 will be down around 5V, and its internal resistance will be pretty high. You certainly aren't going to be able to get 2.5W out of one for long. 0.25W is more achievable, but I still doubt you'll get 12 hours, and with a 2.5W peak load you are going to need a big supercap to smooth the demand.If you are proposing a 6LR61, you obviously don't actually need 12V (or are willing to boost to get it). If you tell us what voltage rails you actually need and the max. and average load current for each, we are more likely to be able to suggest viable solutions."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 11:44:26 am",
"content": "How are the LEDs connected and powered? Please don't say in parallel and from a resistor/linear regulator. If you're going to power them off 12V, they need to be in series, if powered by a resistor/linear regulator. If they're in parallel, either use a lower voltage, or a buck regulator."
},
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 03:43:43 pm",
"content": "Quote from: Zero999 on June 03, 2025, 11:44:26 amThanks, well the LEDs are controlled by code and are connected to three different GPIO ports. They are connected to three pull-down resistors respectively, 470 ohms each. I assume that all the parts of this setup need 5 volts maximum."
},
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 03:46:35 pm",
"content": "Quote from: Ian.M on June 03, 2025, 11:27:41 amThanks for the reply. All of the parts of this setup need 5 volts maximum. If there are 5V batteries with high mah values, I might take a look at them. The high load probably occurs every second when all of the sensors take measurements. The maximum load current, I'm not sure. One of the documents mentioned something like 1.5 mA in average, and up to 50 mA, maximum. That's for one sensor."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 04:10:43 pm",
"content": "Boost converters that can provide 5V out from a lower voltage are readily available. Its probably worth avoiding the ones that can work with a single AA cell as input, as the low input voltage results in much higher current in the coil and switching transistor, thus higher I2R losses and worse efficiency vs those intended for input from 2x (series) AA cells or even a single LiPO. The only fly in the ointment is output ripple and switching noise which may be an issue if you have very sensitive analog sensors. 2x AA cells occupies a similar volume and footprint to a 6LR61, store over 50% more energy and are suitable for a far higher pulsed discharge rate, they are also typically one of the best value for money primary cells. Note that when selecting a boost IC or module, low quiescent current is important, and if using 2x AA cells operating down to under 2V is essential to get >90% of the stored energy out of them. This is less important for LiPOs which should never be discharged much below 3V (at small load currents), so an undervoltage cutoff is a preferred feature.For a one-off I might hack a small powerbank, of the USB charged single 18650 cell variety, but do check its output voltage is adequate when its 'sleeping', and to find out how much load current it needs to wake up."
},
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 04:33:01 pm",
"content": "Quote from: Ian.M on June 03, 2025, 04:10:43 pmThank you. Well, I'm a newbie at this. I guess that by supercap, you mean a capacitor with a high value in Fahrads. Let's pretend that I use a boost IC module, what is a rough estimate for what these batteries you mentioned (2x AA cells) will last with this setup? If I don't use a boost IC (and another kind of battery, maybe the one I suggested), what is a rough estimate for how long that battery will last?"
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 05:39:16 pm",
"content": "Quote from: Johannes79 on June 03, 2025, 03:46:35 pmBut what minimum voltage could they operate on? Your MCU is 3.3V. What about the other parts? Could everything work on 3.3V? Or even 3V? If not, are there alternate 3.3V versions of the parts that require 5V?"
},
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 07:58:28 pm",
"content": "Quote from: Peabody on June 03, 2025, 05:39:16 pmThere is a 5V power input on the MCU, and the parts, except for the LEDs, are connected to it."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 08:25:16 pm",
"content": "here's the GD32VF103 datasheet :https://www.mouser.com/datasheet/2/870/GD32VF103_Datasheet_Rev1_6-3082846.pdf?srsltid=AfmBOooR1GwFlZ4ZQKmGZQ3NTrjg0fC3-zv2V57Gsz4XlqjqOKfVxpXYOn page 48, it showsVDD Supply voltage — 2.6 3.3 3.6 VVDDA Analog supply voltage Same as VDD 2.6 3.3 3.6 VVBAT Battery supply voltage — 1.8 — 3.6 VSo you could probably run the microcontroller with 2.8v, probably at lower frequencies.On page 54, you can see the estimated power consumption in RUN mode and in SLEEP mode, with and without peripherals enabled - at 108 Mhz it consumes 35mA with all peripherals enabled, 20mA without them but if you scale it down to 24-36-48 Mhz you're in the <10mA without peripherals.Unless you need to use white or blue leds with 3v+ forward voltage, you could probably get the voltage down to 2.8v (0.2v higher than minimum)... but I think you'd have to stay with 3.3v because of the lcd and the sensors.If you have a 5v lcd display, you could probably use a 3.3v one, or use a raw lcd segment display and a led segment driver.12v A23 batteries will be really lousy ... you have around 45-55mAh worth of energy. If you use a buck regulator to reduce 12v to 3.3v with around 90-92% efficiency, you'll probably have around 220-250mAh worth of battery capacity.They use 10.3mm x 28.5mm - AAA batteries are just a bit longer at 10.5mm x 44.5mm and you can get up to around 1300mAh in non-rechargeable alkaline batteries.For example, Duracell PX2400 claim to have 1465 mAh worth of energy :https://www.digikey.com/en/products/detail/duracell-industrial-operations-inc/PX2400/16344172The cheaper PC2400 claims to have 1250 mAh :https://www.digikey.com/en/products/detail/duracell-industrial-operations-inc/PC2400/16344166You could easily use a step-up regulator to boost 1.2v...1.5v to 3.3v with around 85-90% efficiency, which would mean you'll have around 500-600mAh worth of capacityExample of step-up regulator ... TPS613221 is 30 cents, and will be ~90% efficient :https://www.digikey.com/en/products/detail/texas-instruments/TPS613221ADBVR/8638375AP6714 would also work (a bit bigger package, MSOP-8) but just as easy to use :https://www.digikey.com/en/products/detail/diodes-incorporated/AP6714M10G-13/1964675TLV61070A would also work, but only if you're gonna use non-rechargeable because it has a minimum startup voltage of 1.3v :https://www.digikey.com/en/products/detail/texas-instruments/TLV61070ADBVR/16982069edit : and if you have space for a 9v battery, just use a couple AA batteries instead or a couple AAA batteries. A step-up regulator will have no problems boosting 2.4v..3.1v to 3.3vOr you could have 3 AAA/AA in series for at least 3.6v if using rechargeable or 4.5v if using alkaline ... a 10-20 cent step-down regulator will have no problem producing 3.3v from this range."
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 09:20:15 pm",
"content": "Quote from: Johannes79 on June 03, 2025, 07:58:28 pmCould you provide a link to your MCU module?And let me ask again - even if the other parts can run on 5V, do they need 5V, or could they run on 3.3V? If you'd provide links to the items you're using, perhaps we can figure this out. If everything can run on 3.3V, then instead of a noisy boost converter you might be able to use a 3.3V linear regulator and a rechargeable lithium cell."
},
{
"post_id": "",
"author": "Buriedcode",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 03, 2025, 10:10:44 pm",
"content": "A schematic will help. Or even a block diagram. You can then estimate/calculate how much power/current each module/part will draw.If you're trying to maximise battery life for a given battery, then things like controlling power to modules so they are only powered when needed helps - and going further sending MCU to sleep when it doesn't need to be used etc.. its how smart phones maintain long battery life despite regularly drawing power that would cause the battery to drain in a cople of hours."
},
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 10:30:44 pm",
"content": "Quote from: mariush on June 03, 2025, 08:25:16 pmThank you very much!"
},
{
"post_id": "",
"author": "Johannes79",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 03, 2025, 10:33:43 pm",
"content": "Quote from: Peabody on June 03, 2025, 09:20:15 pmYeah, they do run on 3.3V. You're right, along with Mariush and others who posted here. Thank you."
}
] |
2025-10-17T16:17:55.295372
| 16
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-and-5v-power-output-equlivenece/
|
12v and 5v power output equivalence - Page 1
|
[
{
"post_id": "",
"author": "danbr",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 07, 2015, 03:48:40 pm",
"content": "I did a quick search and didn't find much.Pretty simple question, although its been racking my brain the past couple days.I'm pulling 12 volts (from a car) with a min fuse value of 5amps. I'm being cautious and saying 2.5amps will be the max current draw allowed by my system.Okay, so 12v X 2.5amps = 30 watts, no big deal.What I'm wondering is, my system runs off 5 volts that I am buck converting down from 12.Is it correct to say:30 watts / 5 volts = 6 amps @ 5 volts? I can safely pull those 6 amps at 5 volts. I am designing my little system around the power requirements/restrictions, so I need to know my power limit.Thanks!"
},
{
"post_id": "",
"author": "SteveLy",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 07, 2015, 04:00:22 pm",
"content": "You basically have the right idea. Power = Voltage x Current. You also need to allow for the less than 100% efficiency of the voltage converter.Suppose the efficiency is H, as in e.g., H = 0.85 for 85%. If you want to get P_out watts out then you need to put P_in/H watts in. For 30W out you need 30W/H in; e.g. H = 0.85, P_out = 30W, P_in = 30W/0.85 = 35.3W; let's say 36W to be on the safe side. Your V_in = 5V source must then supply P_in / V_in = 36W/5V = 7.2A. Equivalently, take the ideal 100% efficiency case input current of 6A you've calculated and divide it by the efficiency of the converter (expressed as a value between 0 and 1)."
},
{
"post_id": "",
"author": "danbr",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 07, 2015, 04:14:43 pm",
"content": "Ah perfect, just the answer I was looking for.Erring on the side of caution should help me out here. The buck converting should be able to supply enough current at the 5 volts, just as long as the overall system doesn't draw more than its rated for.Thank you SteveLy!"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 07, 2015, 04:54:03 pm",
"content": "Its more complex than that. While the engine is running, your nominal 12V supply will typically be about 14V. During engine starts, it can drop to 10V while the starter motor is operating, for anything up to 30 seconds.There is also the issue of protecting your buck converter against spikes on its supply. Googe \"load dump transient\" to see what you are up against. If you are pulling 6A at 5V, you presumably will have quite a lot of valuable electronics on the 5V rail that wouldn't survive the buck converter series chopper transistor shorting out."
},
{
"post_id": "",
"author": "danbr",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 07, 2015, 05:54:04 pm",
"content": "After reading up some, I'm not worried about load dumps, the cars' battery will never be disconnected while the system is running. Cranking is another issue. Since I am not pulling directly from the battery, I'm fairly sure a voltage drop would be pretty crappy, but not the end of the world. The power schottky rectifier should take care of the input voltage dips/ripples, while the beefy 3 - 330uF caps should support the 5v for a couple seconds input voltage dips. I've tested this, and so far no ill effects. The car I'm testing on has an \"eco start/stop\" function, so while unfortunate as it maybe, the car has to restart constantly, ugh. I'll do more power testing/data verification.Thanks for the heads up, learning lots on this project."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 07, 2015, 06:10:19 pm",
"content": "So you want to bet on the vehicle's battery wiring never developing a bad connection?At least its a modern vehicle with a smart engine management system, so it will have some load dump protection (high current TVS clamping) already fitted, probably at or in the alternator, so *IF* your switching regulator has a high enough input voltage rating, you *MAY* be OK."
}
] |
2025-10-17T19:32:26.335272
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-and-5v-rails-out-of-single-15v-supply/
|
+-12V and 5V rails out of single 15V supply - Page 1
|
[
{
"post_id": "",
"author": "newbie666",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 06, 2019, 08:24:46 am",
"content": "Hello,This is my first ever attempt at building switched mode power supply and I'm a complete noob so please be patientRequirements:Input:single supply of 15-20VOutputs:+12V / 1A-12V / 1A5V / 2A50mV ripple on all of the rails is acceptable.I was thinking about using TI's LM2596 for +5 rail as it seems to be quite popular IC.For split rails, should I be looking at split rail converters? The ones I found have rather small output current, even this application note shows examples of rather small output currents:https://www.analog.com/media/en/technical-documentation/application-notes/AN-1106.pdfWould it be easier to use another step down converter and then an inverting one after it to generate negative rail?Again, I have zero experience with this stuff so I'm looking for tips on \"best engineering practice\" for those requirements.Bonus questions: what are your favourite converter ICs that could suit this application?Thanks for help!"
},
{
"post_id": "",
"author": "Calvin",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 07, 2019, 03:42:02 pm",
"content": "Hi,the LT8582 of Analog (formerly known as LinearTec) might do the job of generating the +-12V.The Datasheet features several design samples and all the formuals that help to create Your design.The 5V require only a stepdown converter/regulator or a linear voltage reg.The easier way should be to look for complete dc-dc converter modules which may require only a few external parts for filtering.regardsCalvin"
},
{
"post_id": "",
"author": "MarkL",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 07, 2019, 04:06:22 pm",
"content": "Unless you're rolling your own SMPS to learn about them, I would also use modules.The Recom R-78B-2.0 series meets your requirements for Vin and all Vout and Iout. The -12V is provided by using the negative output wiring option. The ripple is a little higher @ 75mV, but you could provide some additional filtering.https://recom-power.com/pdf/Innoline/R-78B-2.0.pdfThere are other manufactures that make similar products.Beware of dual output modules if you're expecting good regulation on both outputs at the same time (e.g., +12V and -12V). Most modules do not regulate both outputs separately, so loading one output will affect the other."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 07, 2019, 05:39:39 pm",
"content": "What I'd probably do:- 12V synchronous buck regulator. This produces +12V and is rated for about 3A alone.- The buck inductor is dual winding, and the secondary is rectified with the correct phase to get -12V. This works for any combination of load currents, as long as the buck converter is always active (synchronous). (If a non-synchronous regulator is used, the load on +12 must always be greater than the load on -12, otherwise the -12 catch diode takes over and regulation is lost.)- 5V from a separate regulator, which may be the same type, or a different type; cascaded (powered from +12V) or not. Cascading has the advantage of automatic supply sequencing: 12V comes up first, then 5V shortly (or jointly) thereafter. (Sequencing can also be done through the soft-start pin on suitable regulators.) If not cascaded, then the +12V regulator only needs to be rated 2A.- Maybe a single LC at the input and outputs, and laying out the supply section so the inputs and outputs are all to one side. This avoids crossing ground loops, and facilitates good filtering.- If 15V is a little too tight for any regulator, or the input minimum really is lower than this still (say it needs to continue operating, even for momentary or sustained dips to 10V or less), I would choose a SEPIC configuration instead; this can (almost trivially) use secondaries to generate as many voltages as you like, so +/-12V is easy, and +5V is harder (you need a custom 5/12 turns ratio), but that can either be solved by following it up with an LDO to make nice clean 5V, or tweaking the tolerances on everything so both supplies are marginal but it works out (i.e., 5.5V is 10% high, while 11V is 8% low, but this may be acceptable after all -- supplies are largely arbitrary, and rarely need to be well regulated).That's an overview of the production-grade solution, but that may not be all that helpful for a newbie; for that, I would suggest:- Individual buck modules or regulators, as you or others have noted. If board-level, follow the application information and recommended values. 12V 1A should be pretty close to a standard example, or use a design tool.It'll probably work, and not need weird tweaking like compensation done.Or for modules, plop it in, use whatever capacitors are recommended (if any), and there you go. If it's freaking out and you can't figure out why (and maybe you'd need a scope to figure it out?), can always try another module. (Alas, the pinouts may not be compatible. The three-terminal modules are usually the same, so that's nice!)- For -12V, you may try a bootstrap mode regulator. This is shown in the application section, maybe not on LM2596, but a bunch of the SimpleSwitchers show how it's done. Basically the output gets tied to GND, and what used to be GND, gets pushed down and becomes your -12V rail. The input sees the sum, or (15-20V) - (-12V), so you need a reg with a relatively high input voltage rating (>= 40V). It also sees the difference of currents, so you need a 2A regulator for a 1A output.Alternately, use a 12V 1A DC-DC isolator module. Over the top, definitely more cost; but you can put that output wherever the hell you want, and it'll always have 12V (at up to 1A..) across its pins!- Would still recommend input and output filtering. Connect to the inside bulk cap, an inductor of maybe 1uH or less. Put a ceramic cap maybe 1uF on the other side (the external facing side) to ground, and again, arrange the input and outputs at the edge of the area so switching ground loops are avoided. (There's always an internal bulk cap, so overall, this gets you a CLC filter on each terminal.)Easy, this way, to get lots of attenuation at switching frequencies (~100kHz) and modest harmonics (into the 10s MHz); good layout (or even shielding) is required for good attenuation into the 100s MHz.Tim"
},
{
"post_id": "",
"author": "newbie666",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 16, 2019, 03:06:13 pm",
"content": "Thank you all for replies, especially T3sl4co1l for detailed writeup. I spent some time going through a couple of application notes to learn about buck inductors using dual winding inductors to generate bipolar supplies. This one was especially helpful (for posterity):http://www.ti.com/lit/an/slva369a/slva369a.pdfI have a couple of follow up questions. Another application note from Maxim (https://pdfserv.maximintegrated.com/en/an/AN3740.pdf) shows a SEPIC converter in a following configurationApplication note lists following advantages of this circuit:1. Quasiregulated output2. 'Clean' inductor current waveform; less noise generation3. Ripple reduction due to coupled inductors4. Single magnetic component (off-the-shelf 1:1 transformer)- Will ripple be better behaved in SEPIC converter with split supplies than buck configuration?- I can't figure out how this circuit will behave without any load. Does it require minimum load as it is the case for buck configuration with split supplies?Thanks for help!Michal"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 12:59:52 am",
"content": "Has the same |I_buck| > |I_neg| limitation I think.The coupling cap improves regulation by shunting leakage, which is nice.Oh also, that's not SEPIC, but zeta -- which is really the same thing, just swapping the switch and diode. Since it's taking the primary output as well, it's a hybrid buck-zeta really.All currents (input, buck output and flyback output) have discontinuities, so adequate filtering is needed. The buck output may have nonzero current ripple, but it isn't continuous because the inductor current is stolen by the flyback side I think. Hence the mutual minimum load restriction.I think I have the right idea, with regards to operation, just from looking at it; but I would be more confident drawing it out. I recommend the same, or even better, SPICE it and confirm operation.Tim"
},
{
"post_id": "",
"author": "schmitt trigger",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 06:35:29 am",
"content": "If your project’s purpose is to learn something new and flex your brain “muscles “, then by all means design and build your own SMPS.If the purpose is an ancillary function of a larger project, then as others have recommended purchase some ready made modules. It will be faster and cheaper."
}
] |
2025-10-17T18:03:34.410055
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-applied-to-a-9v-battery-gt-problem/
|
12V applied to a 9V battery -> problem? - Page 1
|
[
{
"post_id": "",
"author": "Saimoun",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 16, 2020, 06:43:53 pm",
"content": "HiI have a project I want to be able to run using a 9V battery, or a 12V DC power adapter (the voltage is used for audio so I am thinking might as well get 12V instead of 9 from the DC supply).I was thinking wiring these in parallel, i.e. battery negative to GND and battery positive to +12V in.What will happen is someone leave a 9V battery connected but plugs in the power adapter?ThanksSimon"
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2020, 06:50:18 pm",
"content": "The battery will get hot, and possibly generate enough internal pressure to burst. It will invariably leak even if it doesn't burst.Since a significant amount of current will be flowing through the battery, your power supply may also get hot and may not be able to maintain 12v on it's output. Bottom line is, don't do this."
},
{
"post_id": "",
"author": "Saimoun",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 16, 2020, 07:23:54 pm",
"content": "Ha ha ok, it's pretty clear, thanksHow would you handle it in terms of design, then?And if the DC is 9V?"
},
{
"post_id": "",
"author": "Etesla",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 16, 2020, 07:47:09 pm",
"content": "Just put a diode in series with the 9V input. If you are worried about someone putting 12V on the 9V input, and 9V on the 12V input, then put a diode in series with the 12V input as well."
},
{
"post_id": "",
"author": "Saimoun",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 16, 2020, 08:53:26 pm",
"content": "Oh yea I did not think about that! Well they both need reverse voltage protection, in case someone uses a wrong polarity supply or if someone puts the battery the wrong way, but I was thinking using only one diode connected to both the battery positive and the +12V.But then with a diode on each input it will also protect the battery if someone decides to plug 12V while the battery is still on (the idea is to use either the battery or the 12V DC power supply), correct? Something like the attached diagram."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2020, 08:59:52 pm",
"content": "Yes, two diodes is ideal. If you use a Schottky diode, then the voltage drop will be lower than a silicon diode. If you don't mind surface mount parts, the BAT54C has two diodes in one package and should do the job.https://www.diodes.com/assets/Datasheets/ds11005.pdf"
},
{
"post_id": "",
"author": "Saimoun",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 16, 2020, 09:00:53 pm",
"content": "Ok, great! The BAT54C looks good"
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2020, 08:11:54 am",
"content": "Quote from: simonlasnier on September 16, 2020, 09:00:53 pmYou didn't mention the expected current draw of your device, make sure whatever diode you use is sufficiently rated. If you are powering this from a PP3 size 9v battery, then hopefully you'll be drawing somewhat less then the 200mA maximum of a BAT54C."
},
{
"post_id": "",
"author": "Refrigerator",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2020, 08:31:10 am",
"content": "Most DC barrel jacks have a switched ground, much like in the schematic above. This switch is there for the purpose of switching between the battery and power supply.Also i think a single diode in series with the battery will be good enough because the battery voltage will always be lower than the the power supply voltage. Unless you leave the power supply plugged in when it's off, that is.But shottky diodes are cheap and 0.2V drop compared to 9 or 12V is nothing so you can use two to be 100% safe."
},
{
"post_id": "",
"author": "Saimoun",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 19, 2020, 03:25:30 pm",
"content": "Thank you all for the help. I need the two diodes because I wanted reverse voltage protection, I just did not think it will help protecting the battery as well"
}
] |
2025-10-17T17:42:10.815108
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-arduino-digital-input/
|
12V Arduino digital input - Page 1
|
[
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 23, 2022, 08:39:34 am",
"content": "Hi allI want to detect a 12V signal using an Arduino Nano v3.I've decided to use a NPN transistor to do so. Is it a valid solution? Is it better than using a resistive voltage divider?I've tried the circuit and it looks like it works fine.I've tried to use the 100k res at the base but I don't really know if it's the best value. How to chose it?Thanks"
},
{
"post_id": "",
"author": "madires",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 08:55:32 am",
"content": "A BJT is fine! For calculationg the base resistor please seehttps://wiki.jmehan.com/display/KNOW/Transistors+-+Calculating+Base+Resistor++for+Switchingfor example."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 09:01:28 am",
"content": "The max. hFEof a 2N2219 is 300, (400 at elevated temperatures). As little as one uA leakage current across the switch could therefore pull down the D2 pin enough to register as logic low.The transistor adds complexity and increases the sensitivity of the circuit to noise and leakage, making it significantly worse than a simple potential divider. It does however prevent input over-voltage reaching the Arduino."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 23, 2022, 09:08:12 am",
"content": "Interesting. I wanted to prevent over-voltage even if I think it shouldn't be present. It is connected to an alarm system for home.So should I use a zener diode? how?Thanks"
},
{
"post_id": "",
"author": "DavidAlfa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 09:16:24 am",
"content": "Just use a resistor divider.The input pin has 1uA current leakage typical, this circuit provides 15, should be more than enough.The ESD diode will clamp higher voltages to VCC, the resistor value is high so very little current will actually go into it.Even direct short with 240Vac will input just 0.72mA peak, will hardly cause any issue.Code:(12V)->-*->(4.95V)||"
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 23, 2022, 09:27:53 am",
"content": "Where is the ESD diode?"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 09:35:12 am",
"content": "With that 470K in series with the source you aren't going to have any ESD issues.The IO protection is going to handle a surge of 50mA. To get 50mA through 470K you need 0.05 * 470000 = 23,500VIf it's an arduino based on an AVR then it has reasonable spec ESD diodes inside the chip on each pin. And it is ok to use them so long as you limit the current. (Atmel/Microchip even have an APP Note where you can feed mains voltage into an IO pin through 1meg resistor to look at the AC waveform or do zero crossing)."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 23, 2022, 10:11:33 am",
"content": "Will 15k and 10k resistors do the trick?Aren't those original resistors values too big?"
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 10:42:26 am",
"content": "As Ian says,1 uA of base current could give rise to a collector current of 400uA. That’s a drop of 4V across a 10k resistor. So use ~ 1kIf the input is from a long line, RFI can cause false triggering. If that's the case then you need some filtering and input protection. egDon't ground the far end. Run a ground from your MCU system instead.The base current or Iin= (12-0.7)/(Rb) . So the collector current I(Rc) =hfe*Iin.You have 11.3/10k =1.13mA. Looking at the 2N2219 data sheet, the hfe is at least 100 at low currents.Ic =100*1.13mA =111.3mA. The collector resistor will limit this to 5/1k or 5mA. More than enough to pull the collector below the GPIOs low threshold. 5mA may be a lot of current in your design.A small MOSFET can be used instead- with or with out protection components. [ Specified attachment is not available ]BTW. A 2N2219 is over kill, it will happily switch half an amp. It can work at 100MHz at 200mA or more."
},
{
"post_id": "",
"author": "tunk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 10:57:54 am",
"content": "If the alarm system has a battery, then the voltage most likely will be higher than 12.0V.If you use a voltage divider, adjust the resistors values to reflect this."
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 11:09:47 am",
"content": "Quote from: Lucky-Luka on April 23, 2022, 09:27:53 amWithin the microcontroller. There is a diode between the pin and ground, and the pin and Vdd which are both reverse biased under normal operation. The majority of CMOS ICs will have this."
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 02:43:16 pm",
"content": "Will there ever be a time when the Arduino will be powered down but the 12v signal will still be active? If so, using a voltage divider could possibly back-power the Arduino through the protection diode on the GPIO pin, depending on the resistor values."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 02:52:18 pm",
"content": "It adds complexity but there's a reason they invented the opto-isolator. You may not need the Schmitt Trigger because a) you don't care about the edges heading toward the uC or the uC has Schmitt Trigger inputs.https://learnabout-electronics.org/Semiconductors/opto_52.php"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 03:02:50 pm",
"content": "This is not rocket science and there is no need to over-complicate it.A potential divider with upper resistor 5K1 and lower 3K6 will divide 12V down to 5V. That choice of resistor values is for the closest ratio to the desired 7:5 within the E24 series. The decade chosen is to maintain a relatively low input impedance, drawing a bit over 1mA from the 12V source so it isn't excessively sensitive to 'phantom' voltages due to leakage currents.To protect the MCU against over-voltage you need to clamp the voltage at the potential divider tap. While you could clamp to the supply rails, e.g. using a BAT54S dual series Schottky diode, that risks the 5V rail rising catastrophically if more current gets dumped into it than the load on the rail.As its a digital input, you can use a Zener to clamp it*, cathode to the divider tap, dumping the clamping current to ground. A 5.1V 5% Zener rated for 100mW or more is likely to be suitable. That will provide protection to over +/-35V continuous if you use 1/4W resistors, or over +/-70V with a 1W upper resistor in the divider, the limit being that resistor's dissipation when negative voltage is applied. If there is a significant risk of overvoltage use a fusible resistor for the upper (5K1) one in the divider. As the Zener voltage can rise a little above the MCU's 5V supply (or the supply may be lost), you also need a resistor between the divider tap and the input pin to limit any current flow through the internal protection diodes, and 10K should do nicely.A capacitor in parallel with the Zener may be added to help suppress RFI and glitches, and 10nF with the divider values above will give a -3dB cutoff frequency of 7.5KHz, and have negligible effect on signals under 1KHz. Note that whenever you use a RC filter feeding a digital input, to avoid glitches and possible excessive current consumption from the digital device's supply while the input transitions, the input should have a Schmitt trigger characteristic.* Simple Zener clamping is unsuitable for ADC inputs unless Vref<<Vcc as low voltage Zeners have a relatively soft knee so will tend to leak current reducing the measured voltage as the ADC approaches its full scale count at Vdd."
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 23, 2022, 03:44:37 pm",
"content": "It's easy to overcomplicate a thing like this, but it's also easy to make it too simple.A safe way is to add a voltage divider in front of the transistor. If you put a resistor between the base and emitter, then it will de sensitize the transistor and your transistor won't do anything a s long there is approx 500mV across this resistor. It's a good beginners project to build this on a breadboard.Without such a resistor, the transistor can easily pick up mains hum, especially when you have long wires. You can (and should!) also build this on a breadboard. It's a good learning experience to see what happens and where the limits are.For the actual circuit I would probably just use a voltage divider with a fairly high input impedance. For example 47k and 68k, and combine that with an extra filter capacitor directly on the uC pin to filter out the mains hum and spurious switching.for a real robust situation you can add scottky diodes or a TVS for protection but it's not really needed as long as the input impedance of your circuit is high enough. The AVR pins have internal protection diodes and these can handle a few mA continuously. There is even an official application note in which a mains voltage zero cross detector is made with only a series resistor.Long wires can pick up lots of weird stuff and this may very well require extra filtering. Not only on the input, but also on the power supply.You can also make it more robust in software. For example, sample the input at a fixed frequency, and only accept a change if quite a number of the same input state has been sampled.Also:Buying (and using) an EUR 10 Logic analyzer is always a good thing. These things should be bundled with every \"arduino starter kit\". They work with the open source Sigrok / Pulseview project, and are great for quickly visualizing simple things as on/off digital switches to I2C, UART, SPI and some 100 other serial based protocols.As an intermediate step for the hardware, I recommend to build a very simple circuit on your breadboard. Just build your input section, and then write a simple program that only reads the input pin, and then outputs it to another pin in a tight loop. On that second pin you can either attach the logic analyzer, or a simple LED (with series resistor). This gives you quick feedback to what your input circuit does for example when you touch the wire, or when the wire is close to mains voltage carrying wire."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 23, 2022, 06:32:28 pm",
"content": "Quote from: Doctorandus_P on April 23, 2022, 03:44:37 pmcan you show me what kind of instrument you have in mind?Is the updated version of the circuit ok for you?"
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 24, 2022, 01:35:30 pm",
"content": "It's one of these boxes:https://www.sparkfun.com/products/18627The original \"design\" is from Saleae, and they put the thing in a very expensive custom milled fancy aluminimum box. However, it is not much more then a Cypress CY7C68013A, a voltage regulator and some input protection. Lot's of chinese shops sell these things (Including shipping) for less then the shipping alone from sparkfun.The CY7C68013A microcontroller is a bit of a weird thing. It does not have any flash memory. When you connect it to your PC, it is up to the driver for the device to load firmware into it via the standardized DFU protocol.That last schematic looks OK.The 100nF capacitor only keeps out relatively high frequencies. If you also want to suppress the mains hum, then you need a much bigger capacitor. Something like an 1uF or 10uF electrolytic capacitor in parallel to your ceramic capacitor. For experiments on your breadboard, it's also nice to try out a 1000uf capacitor. such a capacitor is big enough to introduce a clearly visible delay.Sigrok / Pulseview also works with generic development boards for this uC (It recognizes these because they have a different VID/PID pair in the Eeprom), and then it can work with 16 channels, but these generic boards do not have any protection on the input pins."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 24, 2022, 02:13:43 pm",
"content": "Yes, the 'Salae' Logic 8 clones are widely available on Ebay, Amazon and the usual far east e-bazaars, and as long as you stick to the open source Sigrok software and fx2lafw firmware, there are no ethical implications in owning/using one.Caution: some have a 'CLK' pin in place of the second GND pin. This is *NOT* a 'sample now' strobe clock input, but is the CY7C68013A clock output (up to 48MHz), so is a multiple of the sample rate, and is pretty much useless unless you are using it for data acquisition with an parallel ADC or similar. Do *NOT* connect when using it as a logic analyser.Also, if bundled with generic test clips, the clips are almost invariably not fitted with pins to accept the supplied duPont leads, and most likely are not easily solderable. See:https://www.eevblog.com/forum/beginners/soldering-to-strange-metal-contacts/specifically my replies #20 and #23 which show how they *can* be soldered."
},
{
"post_id": "",
"author": "DavidAlfa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 24, 2022, 03:06:17 pm",
"content": "Quote from: Doctorandus_P on April 24, 2022, 01:35:30 pmRomless mcus aren't that strange!In this case it's beneficial, you can run any firmware you want, not requiring flashing the system, risk of bricking...But sure,you can add a default rom. The bootloader reads the eeprom, the first byte defines wether there's a firmare on the eeprom to be loaded(0xC2) ot not(0xC0). And can also boot from external parallel flash.Just happened that I bought one 16-ch version, and received 2.USBee AX-Pro / Saelae eeprom values:https://saturn.ffzg.hr/rot13/index.cgi?action=display_html;page_name=saleae_usbee_cloneBut I programmed these VID/PID so Sigrok recognizes them as 16-ch by default.https://www.sigrok.org/blog/sigrok-firmware-fx2lafw-013-released16ch is limited to 12MHz, as it has double data to send!"
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 26, 2022, 02:03:12 pm",
"content": "I've completed the circuit and it looks like it works in real life.I am doing an add on for a home alarm system.I bring power and signal with the same cable from the central unit to the Arduino Circuit. Basically I have an AI camera connected to the central unit that act as a sensor and I want to add an Arduino circuit controlled speaker that say something before the alarm goes off.Do you spot any major flaw in the design?When the speaker is working the current draw doesn't exceed 0.2A and the speaker is supposed to work for several minutes just when the alarm goes off.Thanksp.s. I've used a trimmer in the voltage divider because I deal with alarm systems that give both 12V and 15V signal and power to my board."
},
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 03:09:34 am",
"content": "Quote from: Lucky-Luka on April 26, 2022, 02:03:12 pmIn that case I would use a transistor like you had in your first post. You won't have to worry so much about the input voltage vs. what you're running your MCU at. For instance, what if you wanted to interface with a 3.3V MCU?To elaborate... you can design the input circuitry of the transistor to fully saturate it over a wide range of input voltages -- like 10 to 30V. On the output side you pull up the collector to whatever Vcc is for your digital logic -- whether it be 3.3, 5V or even higher (e.g. for CMOS logic chips). Now you have a design you don't need to tweak for different situations. The technique goes by the name of \"open collector output\" (or \"open drain output\" if a MOSFET is used)."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 07:23:38 am",
"content": "Maybe an optoisolator then?"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 08:12:40 am",
"content": "Increase R2 to 6.2K in the Zener clamped divider I posted back in reply #13, and you can use it from 9V to 24V, However it is still beneficial to tweak it for the expected input voltage as it is desirable to have a switching threshold roughly in the middle of the range between max. input low and min. input high. If the threshold is too low, (or too high) it will have poor noise immunity. A simple potential divider effectively multiplies the threshold of the gate its feeding by the inverse divider ratio.Ledtester's proposal suffers from the same deficiency, with the added disadvantage that the threshold for a simple common emmitter BJT is rather temperature dependent.Unfortunately, low voltage Zeners have a rather 'soft' knee on their Ir vs Vr characteristic curve, so simple Zener clamping is far less suitable for driving 3.3V (or lower) logic. This can be worked around by using a three resistor divider and clamping a higher divider tap with a higher voltage Zener."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 08:33:14 am",
"content": "Then the opto solution should avoid these problems. No?I want to use this board with 12v-15v input."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 08:49:15 am",
"content": "No. Optocouplers are for isolation or for *EXTREME* level shifting (e.g. when you need to get a logic signal from near-ground to riding on top of a 400V power rail). If you use them with a common ground directly across the input and output sides of the opto, its pointless as its doing exactly the same job as a transistor (BJT) but with much crappier hFE."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 08:59:28 am",
"content": "They have common groud in my board.It should work. Don't you think?"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 09:26:46 am",
"content": "It wont work. You have either made a brain-dead mistake with the opto connections or simply don't understand how to use optocouplers."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 10:09:23 am",
"content": "I have made an error connecting the output of the optocoupler.Having said that, do you think it can work (if properly connected) for my purpose?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 10:13:39 am",
"content": "An opto-coupler will work, but why bother? It's easier and cheaper to just use a BJT."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 10:30:04 am",
"content": "Quote from: Zero999 on April 27, 2022, 10:13:39 amI've noticed that there are at least 3 school of thought...I have started the thread with a BJT solution.Then I was told \"The transistor adds complexity and increases the sensitivity of the circuit to noise and leakage, making it significantly worse than a simple potential divider. It does however prevent input over-voltage reaching the Arduino.\"Other than the voltage divider I thought the opto-coupler would behave better than the BJT solution that I have proposed at the beginning.."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 11:54:30 am",
"content": "I think the voltage divider is the best way to do this. It's simple, cheap and effective.R1 R2VIN────────╱╲╱╲╱╲╱───────┬───────╱╲╱╲╱╲╱───────── 0V18k MCU 10kIOHere's the calculator I used to get the above values, except I inputted 12V for VIN, because I assumes it's automotive and is more typical.https://www.random-science-tools.com/electronics/divider.htm"
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 12:15:43 pm",
"content": "It's not automotive. I connect to an alarm system of a house. I can have both 12V and 15V as HIGH signal."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 12:40:56 pm",
"content": "An optocoupler *can* work (now you've sorted out the output connections so the base is open, not the collector), but if you strap the LED collector and the phototransistor emitter to the *SAME* ground, you've just turned half a buck of optocoupler into an extremely crappy transistor (less than unity current gain and rather high 'Vbe'), not even worth five cents. OTOH it lets you keep the input and output side grounds separate (bring the input ground from the signal source down the same cable), which eliminates ground loops and vastly reduces EMI susceptibility.However they don't tolerate much reverse voltage across the Opto-LED, so adding an anti-parallel diode across it to protect it is a good idea, and if you want to increase its turn-on threshold, either a Zener in series for a reasonably well defined threshold, or a resistor in parallel with the LED + antiparallel diode, (giving a much less well defined threshold based on the LED Vf) can also be helpful. Also the CTRR can drop significantly with LED ageing so if you don't want premature failures in the field, *ALWAYS* design with a factor of two excess CTRR for your application circuit.LTspice sim attached."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 01:09:57 pm",
"content": "So at the end of the day both solutions (voltage divider and opto) can be used without a clear \"winner\"...Shouldn't I use a 4.7 zener in the voltage divider to be more precautionary?I could avoid the 10K res to the input in that way. No?"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 01:40:02 pm",
"content": "Quote from: Lucky-Luka on April 27, 2022, 01:09:57 pmA divider is *CHEAP* and effective, and if high enough resistance, far more tolerant of overvoltage.\"... more precautionary? ...\"A picture is worth a thousand words - show us what you are thinking with a schematic, or fire up a simulator and answer your own question!"
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 01:57:32 pm",
"content": "like this"
},
{
"post_id": "",
"author": "madires",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 02:11:53 pm",
"content": "All roads lead to Rome.Any solution comes with some pros and cons. Choose the one which fits the best and fix the remaining drawbacks in your specific application."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 02:25:59 pm",
"content": "What the <beeping> <beep> is a 100uF capacitor directly connected to an I/O pin doing in there?If the Arduino looses power with any other loads being driven by it or its 5V Vcc rail, that can destroy it by transient current through the offending pin's internal protection diodes.For %DEITY%'s sake add a 10K resistor (or at least >=1K) between the big capacitor and the Arduino pin to limit the current!Better - leave out the big capacitor and de-glitch the input signal in software."
},
{
"post_id": "",
"author": "pigrew",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 02:37:36 pm",
"content": "Quote from: madires on April 27, 2022, 02:11:53 pmSo... what's the application?Is protection from automotive load dumps necessary? Just ESD?What's the bandwidth needed? Is it just a relatively slow pushbutton, or actually a sensor that needs to be detected by the MCU within 5us?The input capacitors would aid in \"debouncing\" a switch. Is that what you want? (yes, they are too big... more like 10nF would be reasonable) (If so, verify your MCU's inputs have Schmitt triggers.. IIRC, they do.).As an aside, I've started to prefer low-side buttons, so something likeVcc<->resistor<->button<->GND. That way, if you accidently short the button's terminals to GND, you won't have any high current paths. On the other hand, if you're using it with a voltage divider, this will cause power consumption when the switch is open. Though, the idle power consumption could be avoided if you then use a high-side PNP transistor to translate the levels (similar to what the first post had, except upside-down)."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 02:51:02 pm",
"content": "How many times do I have to repeat what the application is about?Again: I connect this Arduino board to the central unit of an alarm system for homes.The signal stay high for as long as the central system is programmed keep it high when the alarm goes off.When the signal goes high the speaker say something.In some application the signal can be 12v while in others it can be 15v.I have chosen that big cap because another \"super contributor\" user told me\"Long wires can pick up lots of weird stuff and this may very well require extra filtering. Not only on the input, but also on the power supply.\" ... \"The 100nF capacitor only keeps out relatively high frequencies. If you also want to suppress the mains hum, then you need a much bigger capacitor. Something like an 1uF or 10uF electrolytic capacitor in parallel to your ceramic capacitor. For experiments on your breadboard, it's also nice to try out a 1000uf capacitor. such a capacitor is big enough to introduce a clearly visible delay.\"I haven't understood how I can achieve the following in my circuit:\"As an aside, I've started to prefer low-side buttons, so something like Vcc<->resistor<->button<->GND. That way, if you accidently short the button's terminals to GND, you won't have any high current paths.\""
},
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 03:41:33 pm",
"content": "Quote from: Lucky-Luka on April 27, 2022, 02:51:02 pmHow close will the Arduino be to the central unit? Just a few inches or will there be a long cable run between the two?"
},
{
"post_id": "",
"author": "pigrew",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 03:42:24 pm",
"content": "Quote from: Lucky-Luka on April 27, 2022, 02:51:02 pmApologies for not reading the whole thread. I only looked at the first schematic (with a button) and the last schematic (with only input protection). Since it's not a button (like was shown in the first post), ignore this advice... it doesn't apply.Quote from: Lucky-Luka on April 27, 2022, 02:51:02 pmYou'll get conflicting advice, it's your job to pick the wheat from the chaff and decide what's correct. There are also many correct answers.Since your Vdd bus has a somewhat large load (speaker driver), the capacitor could parasitically power the speaker through the MCU through its high-side ESD protection diode.... this likely would damage the MCU.... The MCU's internal IO pin ESD protection diodes can't handle more than 1 mA (with Vdd=+5V). With such a large capacitor, a series resistor would be needed between the capacitor and the MCU to limit the current to below that level. You could calculate the R*C time constant of the RC filter to be some reasonable time, like a few milliseconds, to choose a smaller capacitor value.I also wouldn't worry about picking up mains hum if your GND, VDD, and signal wires are all coming from the same source, and routed with the same path.The ATMega has a wide input voltage range. It accepts between 0.6*Vdd and Vdd+0.5V as a HIGH. You could design your divider to a slightly lower voltage (to be safer)... so 15V could be divided down to 5V meaning 12V down divide down to 4 V, and everything would still work properly. (With Vdd=5V, the input high range is 3 to 5.5V).A divider by itself, with a small capacitor should be good enough. I don't think the Zener is necessary.If the resistor divider limits the current to <1 mA and you have enough capacitance, it's OK to use the MCU's internal ESD protection diodes.Worst case assume your input is 12V and input power is 0V (user hooked up the input live without hooking up the power first). Assuming 0.5 mA and Vin=18V (extra safe worst case), you'd want >36k of resistance between the input and the MCU. Only if you need faster (perhaps >10 kHz) signals, would I worry about more advanced protection schemes."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 03:50:47 pm",
"content": "Quote from: ledtester on April 27, 2022, 03:41:33 pmSeveral meters: more or less as many meters as between the central unit and the outdoor alarm siren."
},
{
"post_id": "",
"author": "Lucky-Luka",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "April 27, 2022, 04:25:24 pm",
"content": "I was simulating the voltage divider circuit.I cannot understand why a 4.7V zener lower the voltage at the input pin. I thought that it doesn't act if it doesn't see voltages higher than 4.7V."
},
{
"post_id": "",
"author": "pigrew",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 04:31:04 pm",
"content": "Quote from: Lucky-Luka on April 27, 2022, 04:25:24 pmCheck the Zener's datasheet. This one is designed to be 4.7V at 20 mA. It will start to conduct about 380 mV earlier (~4.32 V), so limit the voltage to closer to 4.35 or 4.4V. The 380 mV is Z_VT * I_ZT, and is approximate... You see 3.3V? Perhaps the zener breakdown is much less sharp than I expected based on the Z_VT. It's designed to be a voltage regulator, not a TVS diode.What you're thinking about are TVS diodes. They are rated with a standoff voltage where the reverse leakage current is minimal. The also have a breakdown voltage where they start to conduct (same as the Zener voltage), which will be a few volts above the standoff voltage."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 27, 2022, 04:45:52 pm",
"content": "Low voltage zeners have a rather soft knee. Higher voltage ones where avalanche breakdown dominates have a much sharper knee. Also 1N750's nom. 4.7V zener voltage is specified at 10mA test current and you are only putting about 60uA through it . . ."
}
] |
2025-10-17T17:11:34.412792
| 46
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-automotive-relay-trigger/
|
12v Automotive relay trigger - Page 1
|
[
{
"post_id": "",
"author": "andrewlapham",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 01, 2019, 09:28:59 am",
"content": "hey,I drew up a diagram of what I think would work but need some input. Basically, I need to trigger a 12v relay from an Arduino pin. I'm just not sure if the 2N222 is going to feel the pain and let the magic smoke out or not."
},
{
"post_id": "",
"author": "digsys",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 01, 2019, 10:35:43 am",
"content": "The 2N2222 has a current gain of ~ 100-150X, so if the relay coil is 100mA, all you need is ~2mA. Even if you said 5mA for certainty. Assuming 3V3 op / .005 = 660RI'd just increase your resistor to say 560R and put a 10K from Base to Emitter. You can tweak values depending on coil current."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 01, 2019, 12:25:16 pm",
"content": "Please ignore this if you are just using a car battery as convenient portable power for some gadget in a field somewhere!However if your gadget is going to be fitted to or used in a vehicle, I'd be very wary of transient ground potential differences in an automotive environment. If the transistor emitter, Arduino Ground and buck regulator ground aren't all connected to the same point by relatively short wires, you are likely to have trouble.Also, is the buck regulator rated for automotive use? The transients it may be subjected to are absolutely vicious, and even on a modern well maintained vehicle are not nice and well outside the abs. max. ratings of most commodity switching and linear regulators. Google:\"ISO 16750-2\"or the superseded standard\"ISO 7637\"which may be easier to find the full text of as ISO charge for access to their standards."
},
{
"post_id": "",
"author": "andrewlapham",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 01, 2019, 11:42:23 pm",
"content": "One thing I'm not so sure about now is the ground connections, Should they all be common? Can the 12v and 5v lines share the same ground?"
},
{
"post_id": "",
"author": "ptricks",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 02, 2019, 12:19:48 am",
"content": "Quote from: andrewlapham on July 01, 2019, 11:42:23 pmYes and they have to be for the circuit to work correctly."
},
{
"post_id": "",
"author": "digsys",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "July 02, 2019, 07:27:07 am",
"content": "As good practice, keep all grounds referenced at one point, preferably nearest the power source or inlet. This is especially important if you are using it in a vehicle.At the very least make sure the highest current devices are closest to power source 0V."
}
] |
2025-10-17T18:07:33.747696
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-battery-charger-circuit-using-lm317-(12v-power-supply)/
|
12v Battery Charger Circuit using LM317 (12v Power Supply) - Page 1
|
[
{
"post_id": "",
"author": "queennikki1972",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 30, 2019, 03:45:02 pm",
"content": "Thinking about building this project.https://circuitdigest.com/microcontroller-projects/12v-battery-charger-circuit-diagram-using-lm317but I need someone to tell me if the circuit is incorrect and also decipher the BOM..Specifically the recommended wattage for all resistors and (Diode- Nn007 (3)) Do they mean 1n4007 for example? They also mention a 0.05R - Shunt Resistor/wire but I dont see on the schematic.I wont be using the Arduino nano or lcd"
},
{
"post_id": "",
"author": "queennikki1972",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 30, 2019, 03:54:31 pm",
"content": "Nevermind on the diodes, i see that it should probably be 1.5 amp diodes"
},
{
"post_id": "",
"author": "woodchips",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 30, 2019, 03:57:16 pm",
"content": "What a bizarre circuit!Look in any application note for the 117 for a LA battery charger that is far more subtle. It uses a low value, 0.5 ohm or so. series resistor between the out terminal and the voltage divider going to the adjust pin. This automatically adjusts the charge current as the voltage rises, work out how!"
},
{
"post_id": "",
"author": "queennikki1972",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 30, 2019, 04:11:42 pm",
"content": "found it! Very simple circuit instead of this one.http://www.ti.com/lit/ds/symlink/lm117.pdfpage 24"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2019, 04:23:07 pm",
"content": "Quote from: queennikki1972 on April 30, 2019, 03:45:02 pmConnecting an LM317 current limiter in series with a voltage regulator circuit, like that is a bad idea, because it requires a lot of voltage headroom to work. The LM317 voltage regulator circuit, needs an input voltage of about 3V more than the input. The current regulator circuit needs an additional 1.25V, as that voltage is dropped across the sense resistor: 4.25V. An LM317 voltage and current regulator in series, require an input voltage of around 7.25V more than the output voltage. Then the diode on the output will drop even more voltage.A 12V transformer is much to low for this circuit. It needs an 18V transformer to stand any chance of working properly.Quote from: queennikki1972 on April 30, 2019, 04:11:42 pmYes, that's a better idea. Figure 34, on page 26, is also a good idea, if sensing the current on the negative terminal of the battery, is acceptable."
},
{
"post_id": "",
"author": "queennikki1972",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 30, 2019, 11:15:27 pm",
"content": "http://www.ti.com/lit/ds/symlink/lm317.pdfpage 13 battery charging circuit \"RS\" means current sensing resistor? Im sorry for asking such dumb questions"
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2019, 11:36:41 pm",
"content": "Here is a circuit I found online some time ago. There was a description but I didn't save the URL.I have not built it but looks interesting to play around with."
},
{
"post_id": "",
"author": "queennikki1972",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 30, 2019, 11:46:45 pm",
"content": "MarkF that makes more sense to me. I assume that 1R0 is 1W means 1 WATT resistor."
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 30, 2019, 11:55:45 pm",
"content": "This is not where I initially found the circuit. But here is a write up.https://sites.google.com/site/donutscience/various-projects/the-easiest-diy-lithium-polymer-battery-charger/the-easiest-diy-lithium-polymer-battery-charger---a-bit-moreHere is a link to the first page.https://sites.google.com/site/donutscience/various-projects/the-easiest-diy-lithium-polymer-battery-charger"
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2019, 04:17:36 am",
"content": "Here is the original link:http://www.talkingelectronics.com/projects/200TrCcts/101-200TrCcts.html#84B"
},
{
"post_id": "",
"author": "digsys",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 01, 2019, 06:14:20 am",
"content": "Quote from: queennikki1972errr nope. 1R0 = 1.0 ohms (at 1W as stated)Working with V=IR, as current increases, voltage across the resistor also increases following that formula. At near 0.6V ~= 600mA, it will start to conductand start bringing down the Vop. If you need more current,decreasethe resistor value and vice-versaNote: That type circuit is really only for \"Trickle charging\" at ~ 13.8V, it has no boost capability, as usually ~14.4V. That gets trickier :-)"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2019, 07:41:56 am",
"content": "Quote from: queennikki1972 on April 30, 2019, 11:15:27 pmI thought it meant series resistor, but the naming is arbitrary.Quote from: MarkF on April 30, 2019, 11:36:41 pmIt's probably based around the one on the datasheet I referred to above.http://www.ti.com/lit/ds/symlink/lm117.pdfpage 26.Quote from: digsys on May 01, 2019, 06:14:20 amHe's right. It should be a 1W resistor, to allow some leeway."
},
{
"post_id": "",
"author": "queennikki1972",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 01, 2019, 02:45:40 pm",
"content": "Typo, 1 Ohm at 1 watt is actually what I meant to say. 1R0 1W = 1 Ohm at 1 watt"
}
] |
2025-10-17T18:11:42.743886
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-battery-charger-jumping-up-to-19v/
|
12v Battery charger jumping up to 19v? - Page 1
|
[
{
"post_id": "",
"author": "SpookyGhost",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 20, 2022, 10:17:05 pm",
"content": "I have a NOCO Genius 1 battery charger. Right now I'm using it to charge up a test a bunch of 12v SLA batteries I have laying around from UPS replacementsI've notices that sometimes, the battery charger will spike up to 19v. Is this a charger problem, or some kind of battery problem? Here is a videohttps://youtu.be/HN3CxfZJTjoI fist noticed this when I connected it to a VERY old 12v 16ah SLA battery, it did this and I just assumed it might be normal. I came back to the battery a few hours later, and the charger was idle, and the battery reads just 1vI plugged in a second one of the old 16ah batteries, and after a few hours same thing. Battery completely dead. Since then I've charged maybe 5 batteries with no problem. I plugged in another and noticed the same behavior. But I disconnected that battery and connected a different one, and it does NOT do it. Here is a video of thathttps://youtu.be/PCHJ_AK1BSMAm I missing something here? My main concern is that I use this charger to charge batteries in devices such as a portable generator. I'm assuming devices connected to a 12v battery won't really like 19v!"
},
{
"post_id": "",
"author": "thm_w",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 20, 2022, 11:10:00 pm",
"content": "If they battery is jumping from 14V to 19V like that its dead. Internal impedance is very high.The noco is probably using some probing to determine if its connected to a decent battery that will take a charge. Will be some info in the manual.It should show an error LED after it detects the bad battery and won't try to charge it.It would be good if you had a battery tester, as some batteries will still take charge, but will be almost dead/almost useless."
},
{
"post_id": "",
"author": "SpookyGhost",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 20, 2022, 11:11:22 pm",
"content": "Thanks, good info. The batteries its doing it on are the very oldest ones, so that makes senseDo you think 19v could cause an issue to 12v electronics?Sadly zilch in the book about it spiking up"
},
{
"post_id": "",
"author": "thm_w",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 20, 2022, 11:15:06 pm",
"content": "Quote from: SpookyGhost on January 20, 2022, 11:11:22 pmAny circuit designed to run from automotive 12V would not have an issue.However, if you are using a custom power supply or your own design, then you need to check if it can handle these higher voltages.There is some mention of high voltage here:https://no.co/support/sulfation-and-battery-repair-modebut I dont think that applies to your charger."
},
{
"post_id": "",
"author": "BrokenYugo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 20, 2022, 11:31:21 pm",
"content": "It is almost certainly designed to do that, very dead lead acid batteries will sometimes come back and start taking a charge (typically with permanently degraded performance) if higher voltage is applied at first. As mentioned by others in thread, the battery and anything properly designed for automotive use won't mind it, but if a battery is that far gone it probably won't be useful anyway."
},
{
"post_id": "",
"author": "SpookyGhost",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 20, 2022, 11:32:28 pm",
"content": "Thanks guys, very good informationI'm going to toss those batteries. So far a good few of them seem alright.Now to think of a project for old 12v SLA batteries..."
}
] |
2025-10-17T17:16:13.106682
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-battery-load-and-fan-and-rpms/
|
12V battery load and fan and RPM's - Page 1
|
[
{
"post_id": "",
"author": "Wavedave",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 11, 2025, 07:08:57 pm",
"content": "Hello. I am installing a new 12V computer fan in a clam shell vent for a compost toilet on a boat. The old fan \"crapped out\", no pun intended.I did an online calculation using a 12V (50AH) battery and a 12V fan rated at .08 amps.The fan will run continuous and eventuality, I will hook it up to a 12V solar panel on the boat for trickle charging.It states it will run the fan for 410 hours, using a 12V 50AH battery. I plan on buying a brand name quality 12V Lithium battery.My question is, does that mean the fan will run at the same RPMs for 410 hours or when the voltage slowly drops over time, the fans RPMs will also drop. And if the RPM's drop how fast or slow does that occur?Thank you for taking the time to help me. See photos."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 11, 2025, 08:52:09 pm",
"content": "Li Ion have a very flat discharge and Lead Acid have a decently flat discharge curve. The RPM of the fan will be proportional to the voltage but the range of discharge is only about 20% which is what your RPM variation will be. You could put a 10v linear regulator in series with the FAN (LM317 or discrete- LDO would be nice at end of life) to make the RPM constant (relatively). Running a 12v fan at 10v or so is also a lot quieter and extends fan life and you get \"most\" of the fan CFM.A couple of other things-1. The stated capacity of a battery is generally at a rate of C/20 meaning for a 20 hour discharge. Your .08 A load is about C/600. The battery life will be significantly longer perhaps as much as 10X or more, which really means you could you could use a smaller batteries. If your cell is at or above a 30 hour rate, you can expect much longer life. Power sonic and some of the vendors have capacities at different discharge rates- your time is conservative- probably very.2. You want to have some mechanism so you don't over discharge the battery. The rule for 12v lead acid is 10v (1.65v/cell) and LiIon is similar (2.5v/cell). Though its heavier and larger, an AGM Lead Acid might be superior to a LiIon. They do well in lightly loaded floating charge applications like your solar deal. LiIon like to be discharged at real rates and precisely charged. You can have a little comparator circuit that trips a PFET or similar at the threshold. The circuit can draw .5 mA or so forever without hurting the battery. If you over discharge either chemistry, its hard on them and can basically ruin them.3. I don't know if you need to continuously run the fan. It would seem like if the toilet flushes reasonably well, you could run the fan for 15 minutes or so after each use. You probably want to have a vent stack of some kind to vent the gases that are hopefully downstream or at your holding tank- the holding tank may be vented off the stern. If the toilet is water operated and has standing water in and a trap, you won't have much sewer gas coming back up. (hopefully).Good luck."
},
{
"post_id": "",
"author": "Wavedave",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 11, 2025, 11:39:50 pm",
"content": "jwet. Thank you so much for the detailed reply. It is much appreciated and I learned some things!"
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 11, 2025, 11:48:45 pm",
"content": "You're welcome, use the thanks button, its my perverse way of measuring my impact. Take care."
},
{
"post_id": "",
"author": "jwet",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 13, 2025, 03:48:33 am",
"content": "WaveDaveThis experiece was kind of funny, Its sort of kismet that this question came up and I happened across it. I'm a lifelong sailor, put myself through an EE degree rigging boats on the Chesapeake bay- all manor of electrical, plumbing, running and standing rigging and even some engine work. I then went on to a career in electronic engineering and worked in analog design and did a lot of work with batteries and portable stuff. (at Maxim now Analog Devices). Since retiring, I built my own house with a retired custom home builder friend that taught me a lot- did all the foundation, framing, plumbing, tile work, finish carpentry, flooring and electrical- the only things I contracted out were drywalling and roofing. If you have more questions, I'd be happy to help. I didn't actually know what a composting toilet was- is this designed for the marine environment or are you adapting it? Marine toilets are miserable things that give most boat owners a lot of grief. Anyway, take care and good luck with your project."
},
{
"post_id": "",
"author": "BILLPOD",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 13, 2025, 01:35:36 pm",
"content": "On the boat I used to have, you took a dump or a wiz in a bucket and tossed it overboard, (natural and biodegradable waste)."
},
{
"post_id": "",
"author": "golden_labels",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 13, 2025, 03:30:16 pm",
"content": "Would RPM even matter?Due to my condition I must deal with a lot of foul smell in my toilet. Yet I rely on building’s natural ventilation only. Of course I’m aware a boat will not get the same air flow as a chimney in a tall building. But it still feels like very little flow is needed and a drop in RPM isn’t going to affect that.If I were to add any electronics, I would rather consider a timer.BILLPOD:Yes, and in the past people did the same in their homes. Fortunately more convenient options are available."
},
{
"post_id": "",
"author": "Wavedave",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 13, 2025, 07:40:23 pm",
"content": "That's definitely the route I'm going to take if the compost toilet isn't available or it's not working correctly"
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 14, 2025, 03:18:34 am",
"content": "Quote from: Wavedave on September 11, 2025, 07:08:57 pmSome notes...1. A straight up calculation shows 50/0.08=625 hours, but it's always a bit less than that. 400 would be a good target but that does sound low.2. The RPM's drop roughly as the cube of the voltage, but probably an exponent of 2.5 would be better.3. A lithium battery voltage will not drop that much at first, but then suddenly drop by a lot. You have to provide some kind of cut out protection or you could ruin the battery. That's the most important point because these things are expensive. You can also estimate run time better by incorporating the Peukert factor for that type of battery. As the battery ages though, the run time will decrease. Aging is related to temperature, current draw, and depth of discharge.4. You have to use a quality charger to recharge the battery. Also very important for long life and for safety.5. You could get a huge boost in run time by using a vent that allows free air flow when the boat is moving. If the fan is still in the picture too, it would use less power. If the fan is switched off, it will turn by the air flow which should not impede the air flow very much.\"Crapped out\", kind of funny"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 14, 2025, 03:32:42 am",
"content": "You will probably find quite a difference in efficiency between different fans since they are usually not designed with efficiency in mind.So some testing of various fans might yield you some quite high gains in battery life with the same airflow.I would recommend a larger fan spinning slower and go with a brand that is well known to make good fans, noctua comes to mind.You also want it to have good bearings if it's going to be running a lot. So that's another reason to go with a good quality brand.I think noctua has full specs on their fans so you might be able to search for the best airflow vs watts.My gut says fans designed to be low noise will have better efficiency due to less energy lost as noise."
},
{
"post_id": "",
"author": "kite31",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 14, 2025, 03:50:53 am",
"content": "Look also at AC Infinity fans. Some are ducted."
},
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 14, 2025, 10:11:12 am",
"content": "Depending on your local weather/climate....A PC fan pulling 12V @0.08A = 0.96W Lets call it 1W.My approach.. Multiply this out to get the kWh per 24 hour solar cycle.1W for 1 hour = 1Wh. So in a 24 hour period it will consume 24Wh.Multiply this by 10. 240Wh. Drop the h. You need 240W of solar panels.If you enjoy a lot of sunny days locally, your battery could be as small as 240Wh, smaller in the tropics. If you live somewhere like I do (Ireland) if you want the fan to run over January and Febuary you will probably need twice that.With a 12VLA or 4cell Lion equiv, 240Wh is only a 20Ah battery. Better 40/50Ah for the LA to not risk draining. A 50Ah LFP equivalent \"drop in\" would work on perfectly, with margin and it will last 10 years or more unlike the LA.It all seems to add up to be reasonable. Although a 240W solar panel is about a square meter/yard. If you have plenty of good weather, you could try skimping on a smaller panel.EDIT: If you have any other power systems on the board, such as an existing solar or even battery+shore power+alternator+generator setup, check the battery controller doesn't have a 12V utility output already. The Victron inverters used in many boats have a 12V lead acid charger output (Dseigned for charging the engine start battery independently) which can be used to float your LA from the \"boat batteries\" when needed."
},
{
"post_id": "",
"author": "Nominal Animal",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2025, 06:21:12 pm",
"content": "Quote from: Psi on September 14, 2025, 03:32:42 amSeconded,NF-A14 FLXin particular for example. They even give them 6 year warranties (when used in an enclosure).It does require you to have either an 140mm diameter opening with the fan, or a short section expanding to 140mm diameter. (These are easily 3D printed in e.g. ABS.) Running from (regulated) 12V directly, drawing max. 80mA / 0.96W, it will move 115 m³/h, or about 32 liters (over 1.1 cubic feet)per second. Even with ULNA adapter (11 dBA, quite quiet), it'll still move over 88 m³/h, or about 24 liters (or 0.8 cubic feet) per second. The airflow with ducting will be less than those figures (measured in free air), but still quite significant.You do need to ensure the fan will not be exposed to rain or very humid air (think shower or similar), because these ones are not intended for humid environments at all.The mains voltage and 12V dedicated ducting fans are, but they also cost much more if you aim for similar airflow and low noise operation.The 3-pin fans are easiest to control, because the third pin is just the tachometer return, two pulses per rotation, and you can just leave it flapping in the wind (or connect to ground via a 1k to 10k resistor). The LNA/ULNA adapters are just diodes or resistors that drop the voltage over the fan; the fan speed depending only on the supply voltage.It is not that much more effort to control 4-pin PWM fans, though. The fan speed is controlled by the duty cycle of around 25 kHz PWM open collector signal, pulled up to some voltage within the fan. Something likemy 12V PWM single fan controllerought to work just fine. Today, I'd probably redo the design using CH32X033F8P6 and have JLCPCB do both the PCB and the part assembly. That way, you could add more inputs to the microcontroller, say a microswitch or Hall effect sensor with a magnet, to detect e.g. door opening and closing, and program in timing patterns for the fan. Heck, even make them adjustable with another pot, remote one, where humans can fiddle with the timing and max power depending on the power of the chemical weaponry they deposit in the toilet. The CH32X033F8P6 has a ROM-based USB firmware uploader, so you could even reprogram it on the fly if you keep a laptop with you when you're on the boat.(It does really irk me when people insist on doing all kinds of tricks with diodes and whatnot to interface to fans, when the utterly robust, cheap, and simple method uses just one jellybean N-MOSFETs in SOT-23 (BSS138 or NX138AK) for tach, and another for PWM, and 2-5 pull-up and gate peak current limiting resistors. JLCPCB charges all of 0.02€ per NX138AK when assembled, LCSC 0.0254€ apiece in lots of 20, and Mouser 0.081€ in lots of 10, 0.038 in lots of 100, sopriceorcheapnessain't the reason for doing silly tricks here.)"
}
] |
2025-10-17T16:14:09.101382
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-bi-polar-motor-wiring-to-a4988/
|
12V bi-polar motor wiring to A4988 - Page 1
|
[
{
"post_id": "",
"author": "newtekuser",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 30, 2023, 01:33:54 am",
"content": "I picked up a A4988 driver to use with my 12V bi-polar motor (yes, it's a QFN). In the datasheet I do not see a VMOT pin as per the many articles I found online, but I see VBB1 and VBB2 pins which according to the datasheet are for the load supply. I assume these are for supplying the voltage needed to drive the stepper motor, in my case 12V.Does that mean that I connect both pins of this driver to my 12V rail, or only one? The motor has four pins and no ground or power pins.From what I gather, I need to connect A+,A-, B+,B- wires from the stepper to the OUT1A, OUT2A and OUT2B, OUT2B and connect the VBB1 and VBB2 pins to 12V, is that correct? Where does the 12V ground connect to?Here are my components:https://www.digikey.com/en/products/detail/allegro-microsystems/A4988SETTR-T/2237991https://www.omc-stepperonline.com/dual-shaft-nema-17-bipolar-1-8deg-26ncm-36-8oz-in-0-4a-12v-42x34mm-4-wires-17hs13-0404d"
},
{
"post_id": "",
"author": "JJ_023",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 30, 2023, 07:21:30 pm",
"content": "From what I could tell from the datasheet you would connect OUT1A and OUT1B to A+ and A-. OUT2A and OUT2B to B+ and B-.VBB1 and VBB2 would connect to your 12 V. The ground would be provided through the driver. Is the way I would interpret that datasheet."
},
{
"post_id": "",
"author": "newtekuser",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 31, 2023, 01:01:33 am",
"content": "Quote from: JJ_023 on October 30, 2023, 07:21:30 pmThat's what I was thinking too. I also hooked up DIR and STEP pins to my PIC. Since there are no coil sequences with this driver, I simply turned STEP pin high then low with a 1ms delay in between but nothing happens.There's 12V coming into the driver. I suspect soldering as I barely had paste left. Tomorrow I'll have more coming from Amazon and will \"bake\" it again."
},
{
"post_id": "",
"author": "sarahMCML",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 01, 2023, 02:01:13 am",
"content": "Motor GND basically connects to the Common side of the 2 Sense resistors on pins 23 and 27 of the I.C."
},
{
"post_id": "",
"author": "liaifat85",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 01, 2023, 07:01:31 am",
"content": "To power the A4988 and your stepper motor, you should connect VBB1 and VBB2 pins to your 12V supply. You don't need to connect both pins to the 12V rail. You only need to connect one of them to your 12V supply.Connect A+ and A- of your stepper motor to the OUT1A and OUT1B pins on the A4988 driver and B+ and B- of your stepper motor to the OUT2A and OUT2B pins on the A4988 driver.Connect one of the VBB pins on the A4988 driver to your 12V power supply's positive terminal.Connect the GND (ground) from your 12V power supply to the ground (GND) of the A4988 driver.For further reference, you can check the pinout here.https://www.theengineeringprojects.com/2019/05/introduction-to-a4988.html"
},
{
"post_id": "",
"author": "newtekuser",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 01, 2023, 10:41:16 pm",
"content": "Quote from: liaifat85 on November 01, 2023, 07:01:31 amShouldn’t the GND pin be connected to the ground of the logic supply? Because the VDD pins for the driver are for logic supply according to the datasheet and that’s 5v not 12v."
},
{
"post_id": "",
"author": "liaifat85",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 01, 2023, 10:58:58 pm",
"content": "The ground should be the same for your entire circuit. That means the 12V power supply and 5V logic supply and the Motor driver must have the common GND."
},
{
"post_id": "",
"author": "newtekuser",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "November 02, 2023, 12:16:01 am",
"content": "Quote from: liaifat85 on November 01, 2023, 10:58:58 pmIs this going to be an issue if the rest of the components in my circuit are not 12v tolerant? I.e.: In the circuit I also have a PIC microcontroller, LCD and RTC that operate on 5v max."
}
] |
2025-10-17T16:46:00.899650
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/12v-brightness-control-module/
|
12V Brightness Control Module. - Page 1
|
[
{
"post_id": "",
"author": "Nickk2057",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 23, 2014, 03:26:44 am",
"content": "Hey guys. am trying to make an LED 12V brightness control dimmer for my LED's but am not sure of what i can use out of old electronics. (which i have a ton of them around the house and two sheds) any idea?"
},
{
"post_id": "",
"author": "the_memristor",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "October 23, 2014, 08:26:52 am",
"content": "Hey Nickk2057, you can use the good old NE555 for generating PWM to control the brightness. A nice circuit can be found here:http://www.reuk.co.uk/LED-Dimmer-Circuit.htmI build it up myself several times and it always works like a charm."
},
{
"post_id": "",
"author": "Nickk2057",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 23, 2014, 02:34:34 pm",
"content": "Quote from: the_memristor on October 23, 2014, 08:26:52 amwell the LED's is 12V but 17W what would i use to handle the power?"
},
{
"post_id": "",
"author": "jlmoon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 23, 2014, 02:43:09 pm",
"content": "Drive the 555 with a Power Mosfet.. look up IRF seriesshould do the trick"
},
{
"post_id": "",
"author": "the_memristor",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "October 23, 2014, 02:49:05 pm",
"content": "Quote from: Nickk2057 on October 23, 2014, 02:34:34 pmJust replace the motor with your leds (D3 is not needed by using LEDs)"
},
{
"post_id": "",
"author": "Nickk2057",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 23, 2014, 03:33:00 pm",
"content": "Quote from: the_memristor on October 23, 2014, 02:49:05 pmfrom what i see on that link and on that image is that the LED's will not power all the way down (turn off) on the 555 circuit. but then i seen that i COULD use the Arduino board with a 5V regulator in the circuit to power the Arduino and a MOSFET to the light. i will post a pic in a sec of the lights i am using.EDIT: here is the image of the lights i am using. NOW MIND YOU that i have modded them to be only used as 12V. the one on the right is 17W and the left is 15W"
},
{
"post_id": "",
"author": "Nickk2057",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 23, 2014, 03:45:27 pm",
"content": "also what i am wanting to use these for is to help my friend in his photography by making some lights to help in saving him some money.this is one of the photo's that i helped in the lighting at a shoot with them with a prototype of the lights i did that is a simple on-off."
},
{
"post_id": "",
"author": "the_memristor",
"author_rank": "Newbie",
"is_op": false,
"timestamp": "October 23, 2014, 08:16:33 pm",
"content": "Wow! As I scrolled down the topic on my smartphone your picture was shown full-screen and I nearly got an heart attackVery good photo by the wayYou're right, the range dutyrange of the 555 circuit will between 5% to 95%. I used a potentiometer with a build in rotaryswitch to switch the lamp completly off. Like this one:You can certanly use a Arduino for PWM generationSimple connect a potentiometer (voltage divider configuration) to a ADC pin of the Arduino and set the PWM out according to the ADC value.But take care when selecting the MOSFETs, for example the IRFZ 14 seems to be big enough with I_DS_Max = 10A. BUT if you look to the \"typical output characteristics\", you will see this FET can only drive at VGS = 5V (output voltage of an arduino pin) at a VDS = 0.3V (RDS_on = 0.2 Ohms * 1.5A (I_DS)) a maximum current of 1A. -> Would be a bad choiceBetter: IRFZ44ZPbF with an I_DS_Max = 51A seems much to big, but has much better specs than the IRFZ 14.It's only an advice to be on the safe side"
}
] |
2025-10-17T19:53:29.620337
| 8
|
electronics
|
beginners
| true
|
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