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https://www.eevblog.com/forum/beginners/18650-capacity-testing-with-b6ac/
|
18650 Capacity Testing with B6AC - Page 1
|
[
{
"post_id": "",
"author": "codysmith105",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 20, 2016, 03:09:34 am",
"content": "Hello EEVBlog community,I'm getting into Lithium Ion cell recycling / reuse. This is basically pulling apart laptop battery packs and harvesting the 18650 cells for projects.I bought an imax B6AC v2 charger and have started charging / discharging cells.The first cell I put on the charger was already charged so I discharged it at 1A and I got 2096 mAh out of it (that's according to the charger and was a discharge from 4.1v to 3.1v).I then charged the battery and only measured (again according to the charger) 1560 mAh.These numbers are wildly different.How can 2096 mAh go out and only 1560 go in?Also, what procedure should I use to test cells with this charger / in general.Thanks so much in advance guys.-Cody"
}
] |
2025-10-17T19:18:19.054342
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-charger-5v-boost-ic-selection-help/
|
18650 Charger / 5V boost IC selection Help - Page 1
|
[
{
"post_id": "",
"author": "ct1305",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 02, 2022, 09:24:42 pm",
"content": "Hey guys,Have posted previously about trying to use an off the shelf 18650 charger/5v boost board however I would like the challenge of creating my own that’s more suited to the low current draw application.Specs I would like are:2 x 18650 cells in parallel for higher capacity5v 2a input for charging5v 500mA boosted output4 x leds showing battery percentage/flashing when chargingPush button on/off to turn the boost/charger on and offThe required output current is only in the 50-100mA rangeI am slightly lost on selecting the correct IC/IC’s for this as these seems to be a lot of options. The goal would be to add this to a section of the breakout PCB. Would anyone be able to point me in the right direction with the selection process and schematic?Thanks in advanceChris"
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 03, 2022, 04:34:09 pm",
"content": "I think I linked to my video in your other thread, which includes a circuit using the TP4056 charger and the MT3608 boost converter. But it just has a plain on/off switch ahead of the boost converter, and no blinking lights showing state of charge. (However, the TP4056 has outputs for \"charging\" and \"charged\" LEDs.)One potential problem with designing your own boost converter is that board layout seems to matter a good bit, presumably because of the inductor. I avoid that problem by using modules which someone who knows more than me has designed. There are modules for both the TP4056 and the MT3608, and there's the J5019 module which combines both (but has no protection, load sharing, or on/off switch).It's not clear to me how the charging percentage is determined while charging. You can't just measure voltage because the final charging stage has voltage fixed for quite a while."
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 04, 2022, 12:17:33 am",
"content": "Hi,You dont have to measure charging percentage you just have to measure voltage, and keep the current below the manufacturers specification.When charging these kinds of cells the voltage has to be limited to 4.20 volts (or slightly higher if it is a special type that goes up to 4.35 volts but that's more rare).The current stays limited at some value like 700ma or lower (can be much higher depending on the cell).The voltage will be low, typically 3.5v or so when the charging starts, and the current will be max (let's say 700ma for now). As the cell charges, the voltage rises slowly with a good cell. As the voltage gets near to 4.20 volts (or 4.15v to extend cell life) the current starts to drop due to the control circuit sensing the voltage. The closer the voltage gets to 4.20v the lower the current, until very very close to or at 4.20v the current drops to some low value like 50ma or 20ma (depending on cell). That's when the charging process has to be terminated to keep the cell from being damaged.So there is a bit more to this then charging NiCd cells where you can over charge them somewhat and not do too much damage. The control circuits are not that difficult to understand nor design though so it's something i think anyone can do with a some decent amount of reading on the subject.The most important is not to go over the 4.20v spec i think the max is 4.25v but i never go that high.Not sure why anyone would need a boost circuit for this though i would think a higher voltage would always be available, like 5v for example from a cheap wall wart. One exception is if you wanted to charge from a single or two AA cells where the voltage is only 1.5 to 3v or something, but i think that is a waste of batteries unless it's something you really can not do without."
},
{
"post_id": "",
"author": "Teledog",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 04, 2022, 03:22:21 am",
"content": "Check out Ali Express18650 boost PCBs ready made.. and cheap like borschtNo point in re-inventing the wheel"
}
] |
2025-10-17T17:04:55.002377
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-charger/
|
18650 Charger - Page 1
|
[
{
"post_id": "",
"author": "TorqueRanger",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "December 25, 2015, 03:48:32 pm",
"content": "I have a couple projects that use a 18650 cells and does anyone know a good charging circuit for these ??Thanks"
},
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 25, 2015, 06:48:36 pm",
"content": "Quote from: TorqueRanger on December 25, 2015, 03:48:32 pmI personally like the TP4056 for random applications and do implement the temperature monitoring. You can roll-your-own or get one of those $2 boards online. Most of the TP4056 boards do not implement the temperature monitoring but some has it. For the most part, you wont need temperature monitoring. But when you do have a bad cell, that could save your house from burning down.For day-to-day charging, I use a consumer grade charger."
},
{
"post_id": "",
"author": "Stonent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 25, 2015, 07:08:07 pm",
"content": "The store Five Below in the US has a number of cheap power banks for under $5. The small ones that are 18650 sized have one inside. You could just desolder it and put in a 18650 battery holder. I believe it has that exact chip mentioned previously in it.One of them that I got looks like a Lego brick and has 1 cell inside but molded for 2 cells.If you just want a lot of power on demand, they do have a 6600mAH pack for $5 has 3 cells inside it. Since it came out, the other single cell ones have dropped in price.Here's a teardown video that someone else did on that one."
},
{
"post_id": "",
"author": "doobedoobedo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "December 25, 2015, 07:18:09 pm",
"content": "Another vote for the TP4056https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdfthey're ubiquitous in chinese stuff. Cheap as chips and do the job."
}
] |
2025-10-17T19:27:56.333599
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-pack-for-12v-with-buck/
|
18650 pack for 12v with buck - Page 1
|
[
{
"post_id": "",
"author": "geo999",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 08, 2021, 10:14:52 am",
"content": "Hi all,I need your advice for the following situation:In order to power a camera surveillance system over nigh I've built an 18650 pack in the 7S10P configuration.from that a DPS3005 (30V max input, 5A max output) buck converter is used to get the voltage down to 12-13v or so.the DPS3005 needs a minimum of about 13.76v to give 13v output.for 3.5V min and 4V max per cell we have the following voltages:- 7S : 24.5V discharged, 28V charged- 6S : 21V discharged, 24V charged- 5S : 17.5V discharged, 20V charged- 4S : 14V discharged, 16V charged - minimum configuration for 13v output of buck.the question is:what is the configuration that gives the smallest buck converter loses but still have decent Wh from the pack ?asking this because the 7S at 28V buck input gives about 5W of loses for 13V @35W of consumption.Have not yet tested the other configurations, thus the question.Thank you,George"
},
{
"post_id": "",
"author": "Jwillis",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 09, 2021, 03:31:52 pm",
"content": "Best efficiency is when the power supply voltage is closest value to the load voltage . The 18650 Li ion battery has an optimal voltage of 3.7V so the best would be 4Series or 14.8V . Each parallel increases Amp hours . An amp hour (Ah) is the amount of current that can be drawn for one hour from 100% charge to 80% charge . So depending on the mAh of each cell in parallel added together will give total milliamp hours of the series at 14.8V . Do not mix cells with different mAh ratings . This can led to damage of individual cells ."
}
] |
2025-10-17T17:23:06.888395
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-parallel-sanity-check/
|
18650 parallel sanity check - Page 1
|
[
{
"post_id": "",
"author": "paulca",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "December 30, 2017, 02:01:32 pm",
"content": "So I just want to check in case I've lost the plot, but...I have some 18650 cells out of a brand new laptop pack. They are factory paired in parallel. I have put them into a 3 series 2 parallel configuration in an 18650 battery holder.The cells are 3.7V 2600mAh each, so 3S2P creates a 11.1V (12.6V) 5200mAh pack (which was the rating on the laptop battery before I dismantled it).This means to charge it at 0.5C I supply 2600mAh and charge to 12.6V. For 1C fast charge I supply 5.2Amps, although I think I'll keep that to 5 Amp max.Note, I have a standard balance lead wired to 0V, 3.7V, 7.4V, 11.1V and will be using a dedicated LiIo balance charger."
}
] |
2025-10-17T18:41:45.549260
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-powerstarion/
|
18650 powerstation - Page 1
|
[
{
"post_id": "",
"author": "albach",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "June 16, 2018, 07:18:18 pm",
"content": "Hi guys i recently found my old Energie Station (german brand name form Einhell) which was a 50 Ah sealed Pb gel battery with a charger and some cigarette lighter outlets. I want to do a little water camping trip in the summer and wanted a small reliable energy source for charging my phone and cameras. the Pb battery is dead and now the question arose to replace it witch 18650 cells. I have a few 2p4s packs and 3 of them have the exactly same size a the pb battery.My question is if i use the 2p4s cells and connect them in parallel i get 10v if they are completely (2,5v) per cell empty and 16,8 completely charged (4,2V per cell).For a cigarette lighter output both is wrong. I also want to be able to charge everything off a 12v outlet at camp stations or my car.My idea is to use one stepup converter so get 16,8V for charging to the bms and one boost buck converter to get 12 v to the outlets maybe also two one for each outlet.is there an easier option or are my thoughts correct. I will put fuses in front of the outlets so hopefully only the will blow up in case of an overload or short. Charging is no problem because the cells already have a bms fitted to themthanks for your helpAlbach"
}
] |
2025-10-17T18:30:38.675275
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-protection-ic_s/
|
18650 protection IC's... - Page 1
|
[
{
"post_id": "",
"author": "alank2",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 08, 2016, 03:38:25 am",
"content": "I'm thinking of using an 18650 in a project, but after trying a protected cell in a socket, it is really tight and a PITA. I guess the protection circuit adds too much length.So I've got a couple of questions--Is it an actual IC? Why not just a simple PTC?Also, one concern I have with this type of battery is that I don't want it shorting to anything and creating a high current situation. I was planning on using a PTC on the positive side along with a schottky diode to prevent reverse current flow, but then it occurred to me, what if the exposed part of the battery holder touched anything conductive against another ground on the board. Then I thought, I could put two PTC\"s in. One on the negative side and one on the positive side - what about that idea?"
},
{
"post_id": "",
"author": "Audioguru",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2016, 03:47:17 am",
"content": "A PTC will heat up and limit the charging or discharging current.But it will not limit the charging voltage. It will not detect a full charge and shut off the charging. It also will not detect a low voltage and shut off the load and it will not refuse to charge a battery with a voltage that is too low.Then you will probably have a nice hot fire or explosion without a protection circuit."
},
{
"post_id": "",
"author": "MK14",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2016, 03:50:25 am",
"content": "Quote from: alank2 on March 08, 2016, 03:38:25 amOff-hand I DON'T know the full functionality of the protection chip, but being an IC (and in all likelihood, very well designed as a result), I would imagine it does a lot of protection features, some of which might be completely non-obvious, such as cell temperature management.How did you envisage the PTC preventing over-charging (as in sensible charge rates, but for TOO LONG), or attempts at too deep a discharge, or enforced shutdown if things go bad and/or the cell has expired.Also what about overvoltage ?I'd suggest sticking to keeping the safety circuit, because lithium cell faults can set buildings on fire and stuff, when they go wrong otherwise."
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2016, 03:55:32 am",
"content": "A PTC is only overcurrent protection, you also need undervoltage and overvoltage.The DW-01 and its companion dual MOSFET is probably the cheapest solution that has all the protections you need."
},
{
"post_id": "",
"author": "alank2",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 08, 2016, 04:03:24 am",
"content": "I plan on still using a protected cell - I want to add some protection on top on that. Does the idea of a PTC on the positive and negative side have any merit?"
},
{
"post_id": "",
"author": "MK14",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2016, 04:09:03 am",
"content": "Quote from: alank2 on March 08, 2016, 04:03:24 amIf YOUR circuit (completely external to the battery and its built in protection circuits) can benefit from the PTC, then great.Why are you talking about PTCs, on BOTH the positive and negative sides ?(Assuming the cell remains insulated, inaccessible, to the rest of the circuit, except its terminals, obviously)."
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2016, 04:42:06 am",
"content": "Quote from: alank2 on March 08, 2016, 04:03:24 amWhat extra protection - that is to say, what are the additional issues that you are trying to prevent that the protection circuit doesn't already handle?As above the most common single cell protection circuit has a DW01 protection IC and 8205A dual mosfet, at least for external protection boards, have a read of the DW01 datasheet and see what protections it implements. There is no sense in adding protection against failures that are already protected against.PS: The 18650 holders with a proper coiled spring for negative will fit protected cells better than the ones that just have a bit of bent metal.PS2: You can also get 18650 holders with a protection circuit built into the holder itself, for use with unprotected cells."
},
{
"post_id": "",
"author": "alank2",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 08, 2016, 01:02:20 pm",
"content": "Quote from: MK14 on March 08, 2016, 04:09:03 amThis assumption can't be assumed. The battery will be on the underside of something and some parts of the battery terminals will be accessible."
},
{
"post_id": "",
"author": "MK14",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2016, 02:45:23 pm",
"content": "Quote from: alank2 on March 08, 2016, 01:02:20 pmIt makes more sense now.In general, it is usually best that the battery(s), its holder and any wires connecting it to the main PCB(s). Should be insulated, physically protected, encased etc etc. Enough so that the batteries, are safely away from any kind of accidental short circuits or something.I'm not exactly sure what your project would look like, or do. But it does seem to be beginning to sound like you want to fix one or two PTCs, to make up for the fact that the battery installation is rather/potentially weak and sustainable to shorting out.The thing is, occasionally/rarely (in theory), the safety circuit can fail. So if that happened in your setup, not much else would need to go wrong, for there to potentially be a fire hazard, created.Really everything should be sorted out, the final step being the last compile and download."
},
{
"post_id": "",
"author": "alank2",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 08, 2016, 02:47:33 pm",
"content": "Quote from: MK14 on March 08, 2016, 02:45:23 pmI guess that is what I'm thinking. With the protection IC, and a pretty low current PTC (0.5A) on each terminal, that that might be a pretty solid plan for all situations."
},
{
"post_id": "",
"author": "MK14",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 08, 2016, 02:54:04 pm",
"content": "Quote from: alank2 on March 08, 2016, 02:47:33 pmI think I'm beginning to get it now.Are you saying that if you ONLY had one PTC, say on the positive terminal. The danger could be that the somewhat weak installation of your battery, *could* connect the positive terminal of the battery, WITHOUT going through the PTC. So if it also makes contact with something which goes to the negative terminal. You could have a bad short circuit.But if you have the PTCs on BOTH battery terminals. Then if one fails, and shorts to something. The other battery terminal, still has its PTC, so the current will (hopefully) be limited to a safe 0.5A (500mA)."
},
{
"post_id": "",
"author": "alank2",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 08, 2016, 03:16:38 pm",
"content": "Quote from: MK14 on March 08, 2016, 02:54:04 pmExactly. With both PTC's if the the positive terminal shorts to any local ground, it would still have that PTC on the negative terminal to go through..."
}
] |
2025-10-17T19:22:51.650017
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-series-discharge-protection/
|
18650 series discharge protection - Page 1
|
[
{
"post_id": "",
"author": "alxptt",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 01, 2018, 03:33:47 am",
"content": "Hi! So I've been playing a lot with 18650 batteries, and I'm trying to design circuits that allow them to be used essentially like rechargeable alkalines. You take them out and plug them into a charger, then put them back in your thingy. The problem is, the load I'm using would just keep draining them well past the safety point of 3v or so, and also might discharge too quickly.I'm aware that there are series balancer circuits on eBay -- but are they the best solution if I intend to simply take the batteries out to charge? I'd like something as simple as possible, and they include charging circuitry that I don't need. Can anyone point me in the right direction for finding or making a simple discharge protection circuit?My additional question is, would I need balancing if all I'm doing is discharging the cells? That is, is there a risk of one cell being discharged faster than the others, or would they self-balance during discharge? If the latter is the case, is it possible that I could get away with a simple circuit that cuts the battery off at, say, 12V for a 4S battery pack? I realize this wouldn't have current limiting, but maybe I could achieve it some other way.My goal is to be as simple as possible. Any inspiration would be very appreciated!"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2018, 03:40:19 am",
"content": "Why are you trying to reinvent a wheel? The market is completely saturated with the product you are contemplating. All the parts and assemblies you are talking about are made and produced in China at cost of a few cents per unit. What's more, consumer ready battery products are available from multiple sources that do everything you describe.I really don't understand your goals here."
},
{
"post_id": "",
"author": "alxptt",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 01, 2018, 03:48:41 am",
"content": "Well, for one thing, I want to be able to understand how the components work. Simplifying my design as much as possible makes that more feasible, since I'm a beginner. Just slapping a generic module on might work, but honestly I'd rather use something I actually understand rather than a black box."
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2018, 05:20:59 am",
"content": "The standard China solution is the DW01 Protection IC and 8205 Dual Mosfet, this combination provides over discharge (~2.5v) over charge (~4.35v) over **discharge** current and short circuit protection.Note that it does not protect against over charge current, just discharge, and also note that the typical over charge voltage cut off is quite high (there are different grades of DW01 with different cut offs, but from China who knows what you get).Both ICs are readily available for a few cents on the usual chinese sources, not a complicated circuit.Modules with them already made are also available, including circular ones which get welded and heat-shrunk onto 18650 cells to make them into protected 18650 cells. Ideally that is the best way, put protection circuits right on your 18650 cells.I doubt you can make a cheaper or simpler solution even if you had a couple of opamps spare in a circuit."
},
{
"post_id": "",
"author": "nathanpc",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 01, 2018, 02:04:09 pm",
"content": "You could just buy a simple DW01 module on eBay and be done with it, but apparently you really want to get a better understanding of the circuit which is a great thing.First of all, about the discharge balancing process you've mentioned. The cells are going to discharge at different rates because of the internal impedance of them, it is literally the same process that happens when charging, but in reverse this time, so when discharging a 4S pack to 12V your cells might be at different voltages and this problem just becomes aggravated when you charge the pack back up, so you do still need to balance your pack.Now to the discharge protection circuit, you can learn a lot from datasheets of ICs you might be trying to replicate. For example, if you take a look at theDW01A datasheetyou'll notice that they have provided a block diagram:Of course it is a bit complex since the chip is trying to do multiple things, but if you focus on the left-hand side where the they are describing the over-discharge detector you can see that it's basically just a classic comparator circuit with a voltage reference. For example in this case you could use low-voltage opamps as comparators like theTLV272IP, or even better in this case, theMCP6292which can work down to 2.4V. The circuit would be almost identical, but you could use a 1.8V standard red LED as a voltage reference and then just add a voltage divider to the cell so that 3V would equate to 1.8V at the input of the opamp. Then just use the output of the opamp to cut off the cell using a MOSFET.EDIT: As a simple example for you here's a very simple solution to cut off the load when the cell voltage drops below 3V, this is a very simple circuit of how to use an N-Channel MOSFET on the low-side and a nice base to start your experiments with other circuit topologies."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 01, 2018, 02:22:13 pm",
"content": "Quote from: alxptt on May 01, 2018, 03:48:41 amAs many recommendations, these are not blackbox, all you need is to read their datasheet to understand how it works.As you admitted your self you're a beginner, not to rain your parade, I doubt you can improve much the current design, price wise and size wise.Most sold are rounded to be placed on top of battery, or separated board like this below.Just look at the size compared to a TO-220 sized body, imo, its already quite small."
},
{
"post_id": "",
"author": "alxptt",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 11, 2018, 09:48:55 pm",
"content": "@nathanpcWow, thank you for all that detail! That's fantastic and I really appreciate it!Totally addressed all the initial operation questions I had. I'll definitely be playing with this project as op amp practice.One question though -- since there is a 25k combined resistance in the resistor divider... it will have 0.24 mA of quiescent current draw, right? By my math, if I had a 3Ah cell, it would drain it in about 500 days. Is this correct? I am wondering (not for this project, but in the long term) if there is any way of creating a discharge protection that doesn't have a quiescent current draw, e.g. for an emergency system that's charged once and then left in my emergency backpack, or somesuch. How difficult would that be? (I'm assuming here that the Li Ion cells themselves don't have any significant self-discharge rate, since I'm told by the 18650 people that they don't. let me know if this is wrong!)"
},
{
"post_id": "",
"author": "KL27x",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 11, 2018, 10:17:26 pm",
"content": "Easy way to do this is use something like 3 pin voltage detector which are specifically made for something like this. There is in/power pin, ground pin, and output pin (which you can get in open collector or push/pull logic), and they come in voltage set point in every increment between 2.5-3.3ish V and more, to cover the cutoff voltage you are interested in using, drawing a gnat fart of current.Take the output and connect that to the gate of a logic level Nfet. Connect the source to the ground terminal of the battery, and seal that over. The drain is now the negative terminal of the protected battery.You can put these cells in series and each cell is individually protected. The battery will cut out when the weakest cell hits the limit. But you have to deal with the hysteresis or bounce with your main circuit, somehow.This is two tiny 3 pin components. You technically don't need anything else but maybe a pulldown resistor on the FET gate. 3 components. Add pullup on the output pin of the voltage detector if you use the open collector variant. 4 components, max."
},
{
"post_id": "",
"author": "alxptt",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "May 11, 2018, 11:12:21 pm",
"content": "Quote from: KL27x on May 11, 2018, 10:17:26 pmWhat type of voltage detector chip families should I be looking at here?Quote from: KL27x on May 11, 2018, 10:17:26 pmWhat do you mean, bounce?Quote from: KL27x on May 11, 2018, 10:17:26 pmThat is my favoritest thing ever and I'm stealing it now."
},
{
"post_id": "",
"author": "KL27x",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 11, 2018, 11:48:54 pm",
"content": "QuoteI don't care about brands, but the one I have used is Microchip TC54VC/N xxxx. The VC is logic output. The VN is the open drain. I didn't care too much about cost, so I didn't look at a lot of other options. I just happened to find it one day while looking under \"battery management\" IC's on the Microchip website. Read the datasheet and as far as I can tell you would need to spend a lot of time and space and components cost/count to make something to compete with this and still end up drawing more current. As you can imagine, you are not the first to identify this application. There are many companies who have developed products, such as this, specifically to tackle the problem you are describing.QuoteThis is a common phrase around here. You would not be stealing it from me.QuoteThe cell will rebound and the voltage will rise when the FET switches off. So this protects the cell from damage. It doesn't protect your device from browning out and turning back on/off over and over."
}
] |
2025-10-17T18:32:39.483830
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-solar-charging-setup-for-12v-strip-lights-help-a-newbie-out/
|
18650 solar charging setup for 12V strip lights, help a newbie out - Page 1
|
[
{
"post_id": "",
"author": "TT_Vert",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 21, 2022, 03:40:37 am",
"content": "I enjoy 3D printing and whenever I have an excuse I'll design and print something. Well I had some spare white LEDS from an old illuminated umbrella I made a case/solar panel mount, etc. and used 3P 18650s config using acheap amazon solar charge controllerwhich would also turn the output on/off based on panel current. I also used onecell protection boardand those work great for the 3P setup I was using for that.I then got ambitious and decided to try my hand at a bit larger solar LED project. I used 12V LED tape. All of these lights together draw about 800mA so I decided I'd go w/ a 3S2P setup so my output would see a max of 12.6ish volts and I'd have about 6000mAh of capacity. Well the problem was my panels I was using were at best 5V 500mA. So with my lack of real knowledge I got a boost convertor thinking I could increase the voltage of the solar panel to ~14V to feed the balancing BMS. I used thislithium protection board. The way I have it wired is 5V from solar panel to the Vin of the boost regulator which is set to 19V (The spec for the charge controller board states 16-22Vin) then the output of this boost regulator to the 3S protection board. From that board the Vout goes to the LEDs. Now this did power the leds and the on/off function worked but it didn't appear to be charging. Probably due to the lack of current the solar panel can provide. I was hoping that the solar panel could essentially trickle charge the 18650s but it seems that this protection board needs 12V to initialize the unit. I have over 12V out of the boost convertor but perhaps not enough current, not really sure. Perhaps there is a different/better way I can do this? I had looked at 12V panels but most of them seem quite large which I don't really want to do. Perhaps I go w/ 3V LED strip lights designed to be powered by three AA batteries? Try to go gently on me here, I think I got in a bit over my head but i'm learning lots in the process.ThanksDave"
},
{
"post_id": "",
"author": "TT_Vert",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 24, 2022, 03:15:23 pm",
"content": "No takers huh? I know that first post was a bit long winded but I went ahead and went with a different boost convertor that uses an XL6009 which seems to be cooperating at a lower input voltage/current. I also did away w/ the solar \"charge controller\" and went w/ a BMS that does 3S balancing. It has over/under voltage as well as short circuit protection. Basically I am going from the 5V/500mA solar panel to the boost convertor which is boosting the voltage to 14V which is then feeding the two BMS's I have for each set of 3S 18650 packs. Is this an acceptable/safe way to do this? While bench testing I set my power supply to a current limit of 300mA and 5V which was about the average output I was seeing out of my solar panel. With this setup I'm drawing about 300MA from the bench power supply with a voltage of somewhere under 4V as it was current limiting. Based on my calculations using this solar panel (5V/500mA) , with boosting from 5-14V and about 90% efficiency I'm seeing best case 160mA to the pair of BMS's I'm using. Given the capacity of the 2P3S config and the fact the LEDS are only used for a few minutes a week or so and draw 1A I don't think this charge rate will ever be an issue. Is my math accurate here?Here is my finished product, so far it seems to be functioning as design but I'm just paranoid about charging Li batteries unattended. Pay no attention to the bodge wire"
}
] |
2025-10-17T17:10:16.497360
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18650-spot-welder-advice-needed-please/
|
18650 spot welder advice needed please - Page 1
|
[
{
"post_id": "",
"author": "luddite",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 19, 2021, 01:47:03 am",
"content": "I have a Rockseed 305p power supply.I am looking at this spot welder and need to know if purchasing it will let me spot weld or am I missing something?https://tinyurl.com/pkwuuyxj(link to it)I am hoping to drop a couple of decent amperage cables on it and connect to the power supply.Will that be ok, help would be appreciated thanks"
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 19, 2021, 02:39:23 am",
"content": "For spot welding you will need more current. Maybe get a lightly used car battery and a circuit like this?https://youtu.be/p6XTPPBLiYg"
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 19, 2021, 04:46:38 am",
"content": "I use a capacitive discharge spot welder I built years ago, it's little more than a bank of about 1F worth of capacitors, the biggest stud mount SCR I could find on ebay and a current limited variable power supply built around a LM317. I got a good deal on a bunch of surplus capacitors, otherwise it might be easier to just buy something like a K-weld these days."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 20, 2021, 02:01:12 am",
"content": "https://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/msg1232857/#msg1232857"
}
] |
2025-10-17T17:31:22.278662
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18v-solar-for-charging-12v-batteries/
|
18V solar for charging 12V batteries? - Page 1
|
[
{
"post_id": "",
"author": "asymcon",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 22, 2018, 08:44:21 pm",
"content": "Hey,I have had this question for a while. Can't quite figure out why for are 18V configs used for 12V installations.Most solar cells are most efficient around 0.5V/cell (assumed 50°C surface temp). Typical configuration is 36 cells per panel, which gives around 21V open circuit.The thing is, matched voltage/load for such panels is 18V not 12V.When charging lead-acid at 13.5V, or li-ion at 12.0V, 33% of this potential efficiency is wasted based on the I.V curve of most cells (such as A300 here):https://cs.wmich.edu/~sunseeker/files/A-300%20data%20sheet.pdfPreviously I though that solar controllers act as a dc-dc step-down transformers, but based on results of those I tested, that's not the case.They output the same amps to 12V batteries compared to just the cells.So, where's the catch?How to get maximum output from 18V panel when charging 12V battery?Should I set-up additional buffers closer to matched voltage and then step-down to 12V?Prolly a stupid question, but still..."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 22, 2018, 08:54:44 pm",
"content": "QuoteYou cannot directly attach solar panel to the battery anyway, regardless of the voltage.QuoteThat's some nonsense. To make it linear there will be some huge power dissipation on passing element given that your solar cells are not really tiny.QuoteNow it sounds your measurments were done weirdly. What do you mean by \"just the cells\"? You cannot attach them directly. You should measure current at the input and output of the inverter."
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 22, 2018, 09:03:07 pm",
"content": "It became a standard to overcome age, controller, temperature and wiring losses. I've seen panels barely make 15V at power point. I do have a high performing panel that is only 32 cell. It can be difficult to get any gains with MPPT in the summer with a 12V system. Come winter when it is really needed there is some to be gained. Many simple buck struggle to make 85% efficiency due to the almost 1V loss of the flyback diode. At double the input voltage there are gains to be made. I make charge controllers out of small buck modules and modify them to hold at power point voltage, MPPC. This gets you most of the advantages of MPPT with seasonal changes to the set point. These are ideal for 5V applications to boost power. I bought a couple really cheap PWM modules to see if I could attach these to a buck, but haven't gotten too far. The cheap ones float the negative of the panel which makes them more difficult."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 23, 2018, 04:17:13 am",
"content": "The simplest maximum power point charge controllers use a buck switching regulator so the input must be higher than the output. Ideally the input voltage is twice the output voltage producing a 50% duty cycle in the buck converter for best efficiency but it is not critical."
},
{
"post_id": "",
"author": "digsys",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 23, 2018, 05:16:25 am",
"content": "As others have pointed out - You need at LEAST several volts above max battery voltage to take into account dull / very cloudy days, otherwise you couldwaste all the power, PLUS the converter switching losses. Some (rarer) MPPTs do buck / boost, but usually for specific applications.On top of that the MPPT needs to know if you're using Lead acid or LiIon and if it's full or empty. ie have some sort of charge profile. If this isn't done,you may just see max voltage on the batteries all the time (not a good thing), and then just waster energy. Not as simple as plug and play.MPPTs are not just a simple DC-DC charger."
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 23, 2018, 02:08:42 pm",
"content": "Just one of those things like why are there no \"B\" batteries and why aren't there 8V car batteries (both of which exist). You shouldn't be using buggy whip 12V or 24V panels over 50W. Those panels are so yesterday. You are aware that to equalize a flooded battery the voltage may have to get to 15.6V. A 30V 40 cell grid tie panel won't charge a 24V battery. For practicality, the cells have to be square and that leaves you with limited arrangements like 4X8, 4X9, 4X10 etc."
}
] |
2025-10-17T18:26:32.295535
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/18w-amplifier-using-tda2030/
|
18w amplifier using tda2030 - Page 1
|
[
{
"post_id": "",
"author": "iitsanup",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "February 05, 2014, 11:47:24 am",
"content": "hi ,i have build an amplifier circuit using tda2030 as in the attachment , but i have done only stereo part and not the sub woofer.now the thing is the amplifier is working fine only if i increase/ decrease the volume of one side(LHS/RHs) if i do the both a craking noise comes. pls help me. i want to listen in both speakers."
},
{
"post_id": "",
"author": "grumpydoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 05, 2014, 12:03:15 pm",
"content": "I'm not sure what your problem is.Do you have a dual-gang potentiometer for the volume control or two single-gang ones?Do you mean that you get a crackling sound as you turn the volume control (which then stops when you stop turning the volume control?If so then a dry joint on the pot might be the cause. Or a DC potential across the track although if you have built the circuit correctly this should not happen as there is a capacitor to block any DC.Do you mean that you hear crackling distortion when both channels are in operation but not if only one has the volume turned up?If so then I'd look at the power supply - a single 7812/7912 is a bit marginal for a TDA2030 and I think inadequate for two or three as it is a 1A regulator. You might find the supply voltage is dropping low and you are getting clipping when that happens.Or do you mean something else?"
},
{
"post_id": "",
"author": "dr_p",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 05, 2014, 12:16:58 pm",
"content": "If both channels work at low volume, but not at full power, check the power supply. I suspect that as the current consumption increases, the ripple is getting higher, reaching too low of a voltage for the TDA2030 to output the required power. Measure AC voltage on the filter caps or put a scope on it. If it's the case, increase the size of the filter caps.BTW, do you need regulated +/- 12V for the op-amps? Where did this schematic come from? I'm just curious.@grumpydoc: only the op-amps are regulated(V+ and V-), the TDA2030s get the VDD ans VSS"
},
{
"post_id": "",
"author": "grumpydoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 05, 2014, 12:25:41 pm",
"content": "QuoteMissed that, thanks.We both agree it sounds like the PSU is the probem. I think it's worth the OP making sure that he's not feeding the TDA2030 from the regulated supply and that his transformer is adequately rated."
}
] |
2025-10-17T20:08:45.569646
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/19-yr-old-250v-cornell-dublier-electrolytic-caps-still-trustable/
|
19-yr old 250v Cornell-Dublier Electrolytic caps - still trustable? - Page 1
|
[
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "May 19, 2015, 02:13:09 am",
"content": "Lately I got some work shutting down and scrapping some big tri-phase inverters. Amongst the gems, were 18 x 9,100uf 250v caps, similar Spragues, some HiCon 6,800uf 250v, and some 6 other 2,100uf 400v Nippon Chemi-con's. Yesterday, I charged them all for about 20 seconds to 180 volts and today, most are still above 100vThey were just pulled from working equipment, but will my shelving them cause them harm? Should I be hurried to put them to other use?"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2015, 10:53:48 am",
"content": "At worst, they might need to be reformed (charged slowly up to rated voltage with a limited current). If they were in continuous or infrequent use until recently, they're probably perfectly fine.ESR might go up if they dry out, but if they weren't heavily used, that should be fine as well.You might not be able to measure the ESR because it will be fairly low for capacitors of that size.Tim"
},
{
"post_id": "",
"author": "rsjsouza",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2015, 11:25:31 am",
"content": "As said by T3sl4co1l, they are probably fine if they were not exposed to extended use or extreme conditions (temperature, humidity, etc.)A good thread that discusses older capacitors and reforming ishere"
},
{
"post_id": "",
"author": "macboy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2015, 01:05:09 pm",
"content": "I would not hesitate to use those caps. I might be tempted to reform them first.I would, however, have reservations about putting 180 VDC, from a capacitor capable of delivering immense current, across that $5 multimeter."
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "May 19, 2015, 01:13:42 pm",
"content": "Thanks rsjsouza, nice thread indeed! Although Dexter's Lab YT channel diverted me for a while..I'm planning to use two of the caps on the far left to view inductor saturation traces.Macboy, yes they were 5.99 a few months ago I believe.. but your point is well taken. I got three of those from crappy-tire to use as my shop floaters. But then again, what could happen in one milli-second?"
},
{
"post_id": "",
"author": "eas",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 21, 2015, 09:42:11 pm",
"content": "Quote from: Cliff Matthews on May 19, 2015, 01:13:42 pmWell..."
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "May 28, 2015, 07:45:59 pm",
"content": "FWIW, 12 days past since charging all to 180v and out of 24, only 2 self-discharged within ~3 days. The others still measured between 20 and 40 volts before I discharged them with a 4.7k resistor.An odd observation:All were rated 250v except the 4 smaller (2100uF/400v Nippon Chemi-Con's) on the right - It is these, despite being of smaller capacitance, that retained the highest charge. Is this brand just better? or was it the dielectric?"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 28, 2015, 11:33:15 pm",
"content": "If you didn't reform them (idle up to rated voltage with a limited current supply), the leakage can be expected to be very large, especially at voltages near the rating (and proportional to it).One would suppose the 400V caps are in a \"formed\" state such that their leakage at equal voltages (and therefore smaller V / Vmax) is lower.Value doesn't matter; self discharge is essentially a time constant. Obviously, bigger caps have more potentially-leaky area, and higher voltage caps have thicker area.Tim"
}
] |
2025-10-17T19:39:51.331310
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1933-philco-model-44h/
|
1933 Philco Model 44H - Page 1
|
[
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 13, 2023, 10:02:33 pm",
"content": "I have the chance/opportunity to pick up, what appears to be, a nice 1933 Philco Model 44 radio. I'm not sure it still works but it appears to have been keep indoors (not in a garage) and is in good shape.The schematics seem to be somewhat available. Have any of you ever worked on one of these? Would you do it again?Thank you,- Wil"
},
{
"post_id": "",
"author": "Circlotron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 13, 2023, 11:16:36 pm",
"content": "3-gang tuning capacitor so it almost certainly has a tuned RF stage. Better than most, so it should be a good performer.Edit -> on closer inspection it looks like the tuning capacitor has two large and two smaller sections, the smaller ones possibly for short wave bands.https://philcoradio.com/gallery2/images/1933d%20-%20Fall%201933/1933d.h%20-%20Model%2044H/image_04.jpg"
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 14, 2023, 12:18:59 am",
"content": "I scrapped one for parts nearly 60 years ago as a teenager. Yours looks very nice and worth restoring. Electrolytic capacitors will be dry and dead, and the tubes of that era are getting hard to come by. The one I parted out had many mica capacitors which should be just fine today, unlike the wax dipped paper used in later models. Resistors could be fine, or could have drifted badly over the years. By the way many of the components appeared very different than later decades. This radio was fairly early in the standardization of the electronics industry and styles in use then didn't last too long. By todays standards the circuitry is very simple, though the wiring methods are confusing to those who entered the hobby after PWBs took over. Be cautious of the high voltages. One hand in the pocket, be wary of charge stored in capacitors. The main object of my scrapping was that big power transformer seen at the left of the chassis top view. I still have the high voltage power supply that resulted."
},
{
"post_id": "",
"author": "Wallace Gasiewicz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 16, 2023, 08:42:07 pm",
"content": "These big old radios sound great. The big ones are usually not as valuable as the smaller table top ones because it is hard to find the room to collect more than one or two. But they do have better sound.The speaker is usually an electromagnet rather than a permanent magnet and the high voltage supply goes thru it. It uses the speaker electromagnet not only for the speaker but as a big choke inductor to filter the High Volts. So be careful. If the speaker is damaged there are lots of people who have used different materials to replace even the cone.Real purists will gut the old cap cans and stuff in new caps for the look. Others will just disconnect the old caps and wire in new caps under the chassis. The old big electrolyte caps had quite a large range of tolerances in their capacitance, so do not be too fussy in choosing replacements."
},
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 16, 2023, 09:52:32 pm",
"content": "I haven't opt'd to purchase this one (yet). He wanted a bit too much for it in my opinion so I'm going to finish the one I'm working on now before tackling anything new.- Wil"
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 16, 2023, 11:49:43 pm",
"content": "Quote from: Wil_Bloodworth on November 16, 2023, 09:52:32 pmOut of curiosity, what is he asking? I do expect prices in this market to drop as people of the age are starting to drop out and AM broadcasts are declining."
},
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 17, 2023, 12:27:32 am",
"content": "https://dallas.craigslist.org/dal/ele/d/plano-philco-radio-model-super-cool/7681831515.html$65"
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 17, 2023, 12:38:21 am",
"content": "Quote from: Wil_Bloodworth on November 17, 2023, 12:27:32 amThat actually seems like a good price to me. If I lived in the area I would buy it, largely because of the connection to my past. Cabinet is in great shape and it appears to all be there. The biggest holdup is whether you have room and interest to keep it."
},
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 17, 2023, 12:45:59 am",
"content": "It's not the price that concerns me at all. My main concern, which causes the reservations of purchasing the Philco, is that I am in the middle of attempting to fix the first radio I've ever tried to restore and I'm not sure I'm going to be able to pull it off. I just don't have the necessary tools or knowledge so if I fail, it will all just go in the trash and I'll probably just end up learning how to fish instead.- Wil"
},
{
"post_id": "",
"author": "retiredfeline",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 17, 2023, 01:19:48 am",
"content": "It's alright to fail more than once in a project."
},
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 17, 2023, 01:36:45 am",
"content": "That is true. However, if I get stuck with something that isn't working, I don't have any local resources who can help get me unstuck. The online resources I feel that I could rely on are probably going to ask things I don't understand or have no way to measure. All the pessimism aside, this is purely conjecture on my part as I don't even know if I will get stuck.It's akin to a blacksmith stumbling across a Ferrari that has been left in the forest for 50 years and he's decided to get it running. While the blacksmith has amazing intentions, hopes, and dreams... reality always shows up.- Wil"
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 17, 2023, 02:35:30 am",
"content": "If you are careful with the mechanical work you will not destroy the value. If you come up against a bigger obstacle than you wish to cross you will have little trouble recovering your investment."
},
{
"post_id": "",
"author": "Wallace Gasiewicz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 17, 2023, 02:00:15 pm",
"content": "Wil: Do not despair and do not sell yourself short.Your first attempt is not the easiest one but it is not horribly complicated.People designed and fixed these things with the limited test equipment available at the time.Things like oscilloscopes were not available. A nano VNA was as far away as \"Star Trek\", you could probably buy a running automobile for what it cost for a top of the line multimeter.The best repair technician I have ever met mostly used only a 30 MHz scope, he was very disabled by arthritis and could not walk and could barely light a cigarette with his gnarled hands, but he always fixed the thing. He did have digital multimeters but he used an analog multimeter because he did not like the digital readout ones.I use both analog and digital, digital meters are better, I buy interesting analog meters at Hamfests for $10 because they are cool and do not take up much room in the shack. Besides, some of the military ones have Kilo Volt capabilities that I use once or twice a year. You need special High Volt probes and test leads for this. You don't need this now.This is part of the Test Equipment Anonymous (see the Test Equip Forum) it is referred to as GAS or Gear Acquisition Syndrome and cannot be treated with conventional psychotherapy.On your first repair: Replace the components one by one, and try to understand where they go on the schematic while putting them in the actual radio, that thing is eminently repairable.Remember, you are in it as a hobby, there are lots of people here who are professionals and have worked in electronics for decades after getting various degrees. This is their living. Yours is a hobby. Hobbies cost money and it is quite rare for a hobby to generate money or even break even. I have managed to make a little money fixing things to buy more stuff, but I do not think I could actually make a good living doing this stuff.Stick with your first repair attempt,Old Radios are out there and will come to you when they feel like it. If the neighborhood finds out you are interested in old radios, so many will appear that you will be sorry anyone knows about your hobby.After you have replaced the components you think need replacing, and the tubes light up, you can see what sort of test equip you need. On your radio either all the tubes will light up or none, as you know (see, you already know something that most people do not)Sometimes the thing comes to life and needs very little adjustment.All you need to tune the thing is a signal, whether that is a good AM station or agenerator with AM modulation. If you get some sound out of the speaker, you can tune the radio.Again, go to some Hamfests and talk to people, someone WILL have some stuff that you can buy cheaply."
},
{
"post_id": "",
"author": "rsjsouza",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 17, 2023, 04:06:21 pm",
"content": "Wil, that is very, very cheap for its state. I was tempted to get it but, as you can imagine, the problem is the large room to work on this (and the wife approval factor, which is close to nil for a new project).I can help with repair tips if needed (I live on the same general area).Good luck in your decision!"
},
{
"post_id": "",
"author": "CatalinaWOW",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 17, 2023, 04:32:15 pm",
"content": "Wallace has excellent advice. Do note that all or none tube lighting up is a feature of most AM radios from the mid/late 1930s through the end of the tube era, but is not true for the Philco 44 you are looking at. The transformer has a 6.3 VAC winding and all the tubes are connected in parallel to that winding. This does make it easier to find a tube (or tubes) with a burned out filament as they will be the ones that don't get warm/light up."
},
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 17, 2023, 06:03:30 pm",
"content": "If I don't have a tube tester, can I not just pull out each tube individually and apply the appropriate/required amount of DC voltage to the filament pins to make sure it lights up? Is there any reason to even do this if I have already tested continuity on the filament pins?- Wil"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 17, 2023, 06:33:30 pm",
"content": "The \"cold\" heater resistance of these tubes is not specified, so a \"continuity\" test is not conclusive, unless the resistance is essentially infinite (blown heater).If you want a definitive test, you can apply 6.3 V DC through an ammeter, since the current at 6.3 V is defined on the datasheet.(That would be safer if you use a lab supply with an adjustable current limit.)On your earlier radio repair, the heaters were in series."
},
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 17, 2023, 06:53:43 pm",
"content": "Thank you Tim. I do have a bench DC power supply where I can limit the voltage and the current so I will try that!- Wil"
}
] |
2025-10-17T16:45:17.981931
| 18
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1946-mason-45-4-progress-made/
|
1946 Mason 45-4 - Progress Made - Page 1
|
[
{
"post_id": "",
"author": "Wil_Bloodworth",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 26, 2023, 11:29:08 pm",
"content": "Well, all of the components have been (poorly) replaced. I started at one end and worked toward the other and it was very apparent that my soldering abilities leave ample room for improvement. However, I did notice that I got better as I went along and I found myself in a slightly different mindset where I would mentally remind myself of certain things to not forget about. I tried using heat shrink tubing in a few places; mostly because I wanted to experiment. Mr. Carlson recommended the white sheathing that is seen in a couple of places in the image below. I very much prefer the white tubing to the heat shrink but I can see different purposes for each.The new polarized plug looks nice I think. Next, I need to put the IF 1 transformer back in and then figure out the antenna wires and how they're supposed to be wired up. That is a different educational journey that I will explore tomorrow.She will be soon ready to turn on (via the isolation transformer/variac/dim-bulb rig) and do some measuring and, with any luck, attempt to get a new speaker hooked up. I think I can do the IF alignment with a dummy load but honestly, I think that is a bit above my pay grade at the moment so I'll just take it slow and go the easiest route for now.Enjoy!- Wil"
}
] |
2025-10-17T16:44:43.611744
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1950s-houses-mains-earthing-and-the-cable-guy/
|
1950s Houses, Mains Earthing, and the Cable Guy. - Page 1
|
[
{
"post_id": "",
"author": "SgtRock",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 05, 2011, 03:31:37 am",
"content": "Greeting EEVBees:--Herein pends a long tale of woe, with an eventual happy ending.--My neighborhood is composed of 1950s houses. Many have original 2 wire runs from the breaker box to the sockets. My neighbor's house had 2 wire cable running to the sockets, but of course some jake leg had hooked up 3 pin sockets to the 2 wire cable and left the ground unconnected. This is a very common practice in my neighborhood, and is probably endemic in similar situations in the US.--My neighbor, Mike, was having a lot of trouble with his BrightHouse internet connection going intermittent at odd intervals. I had him get a good UPS and hooked it up for him. When I hooked up the UPS I noticed that the \"No Ground\" light was lit up. I checked the socket, and \"Bobs your uncle\" there was no ground. I did notice however that if I ran the BrightHouse cable through the UPS it would pick up the ground from the BrightHouse cable. Parenthetically, I should add that both Mike and I were in the Poor House at the time, so calling a licensed electrician was out of the question. Problem solved??--It turns out that although his computer, router, etc. was now protected from spikes and short term outages, the internet connection was still fritzy.--Mike would call, and the cable guy would come out and say; \"Well there's your problem, you have the cable run through the UPS. That interferes with our signal.\" I pointed out to the BH man that the problem predated the installation of the UPS and that I had been running an identical setup at my house for two years with no problems. Needless to say, my statement had no effect on the BH man. He disconnected the UPS, pronounced the problem solved and left, mumbling and shaking his head at the stupidity of customers.--Surprisingly, the intermittent outages continued, and Mike would re-engage the UPS, call BH and the whole scenario would repeat ad nauseum. But now a new factor was introduced. SWMBO decreed a move of the system to a new location, which required putting the old HP computer on the concrete floor. Now when the BH man disconnected the UPS, the old HP computer case (with bare metal on the bottom of the case and no rubber pads), went to floating intermittent ground, and as a result a spike somewhere in the system caused the microprocessor to go NFW.--BH at first promised to recompense Mike for his computer, but upon review by a higher manager decided to disallow his claim because of \"use of unrecommended equipment\" which, oddly enough was not being used at the time. We soon gave up trying to penetrate the thorny BH hedgerow. SWMBO summoned \"virtual money\" out of the ether, and a cheap reconditioned computer was procured.--Upon being informed of these events, I proclaimed \"FT\". We then managed ,\"hook or crook\", to obtain green coated grounding wire, green wire nuts, grounding clamps, and ground pegs. I then proceeded to connect all grounds to each other every which way. On the inside walls I found an unconnected ground wire, \"Bob's your uncle\". The outside walls were original and there was no ground wire. So, I used a 1 foot drill bit to bull my way through the metal box and on through to the outside of the walls.--I then proceeded to interconnect all ground wires to the Progress Energy ground wire, the copper water pipes, and the ground pegs in a bewildering array. The network was so complex that no jake leg, shade tree electrician, or BH man would ever be able to figure out how to defeat it, let alone doing the work involved.--The end result had been that Mike has had no electrical failures whatsoever in two and half years. His \"state of the art\" washing machine, which used to require replacement of the microprocessor twice a year, now has no problems.--One would think the \"maintenance contract\" guys would check for ground, but apparently they work like government employees, and regard underlying problems as allies.--One of my other neighbors \"Jesus\", pronounced \"Hey Zeus\" as if one were addressing the \"Father of Gods\", has the same two wire cable to 3 pin sockets setup, I.E. no ground. In Jesus' case I installed a common UPS and ran the cable through it, obtaining a \"jury rigged ground\" Result? No problems whatsoever in the past two years.--After a suitable time for responses, I plan to forward this entire thread (redacted of names, identities and so forth) to the CEOs of BH and several UPS manufacturers.--I invite and welcome your comments. I particularly would like to hear stories of similar problems. Contraian remarks are always welcome, but I would prefer concrete assertions rather than derision and sarcasm. I freely admit I have been feeling in the dark, and trying in my humble way to follow what I have been told in this respected forum. Best RegardsClear Ether"
},
{
"post_id": "",
"author": "PetrosA",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 04:34:45 am",
"content": "Using the UPS to bond/establish the ground might work, but it can be a dangerous thing. Typically, the grounds would be bonded together at the ground rod with pretty hefty wires (size depending on what system they're bonding). Since the ground's main purpose is to drain surges, and the bond's main purpose is to redirect fault current back to the neutral, if you establish a ground at a UPS through the coax cable, then that small cable will carry any surges or fault currents which could get ugly when they get big (like from a lightning strike). The best, and probably cheapest option would be to run a new line to feed the PC and router."
},
{
"post_id": "",
"author": "SgtRock",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 05, 2011, 06:02:36 am",
"content": "Dear PetrosA:--I am completely in agreement with your remarks. Stealing ground from the cable company is only a \"temporary, no money solution\". If one has no ground at the socket and one routes the cable through the UPS, that is what obtains. Assuming an uneducated, and ungrounded customer with little or no money: Would you recommend using the Cable Company ground or not?\"Three weeks in the lab will save you a day in the library every time\" Stanley Williams, HP LabsBest RegardsClear Ether"
},
{
"post_id": "",
"author": "Computeruser",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 12:29:22 pm",
"content": "That is a very interesting story. It is hard to tell if the added grounding is effective in this case, but I respect the fact that you have tried to add grounding. Good move.I know it is circumstantial good fortune, but my current home (I posted elsewhere here) came with excellent grounded wiring and outlets.... C"
},
{
"post_id": "",
"author": "PetrosA",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 05:03:58 pm",
"content": "I can't recommend using the cable company's ground for grounding electrical devices. The most likely danger is that the cable guy will disconnect the cable outside somewhere and it will be carrying some current from the UPS. Cables have been known to burn up from being incorrectly connected to the electrical system as well. The cheapest solution is to run a single ground wire (min. 14 AWG) back from a grounded outlet to the nearest bonded cold water pipe or panel. The UPS needs a good ground to shunt surges, and the cable ground is simply not designed for that. I have seen ungrounded UPS's wreak havoc with PCs and other electronics when they don't have a ground."
},
{
"post_id": "",
"author": "Computeruser",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 05:30:38 pm",
"content": ">>> I can't recommend using the cable company's ground for grounding electrical devices.I agree, but it may have been better than nothing in those circumstances.>>> The cheapest solution is to run a single ground wire (min. 14 AWG) back from a grounded outlet to the nearest bonded cold water pipe or panelI much agree with this, I suppose, because that is what I have seen all my life.Thank you for an informative post. .... C"
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 05:57:26 pm",
"content": "The reason that attaching a ground lead to the cable companies ground pin is that it doesn't actually fulfill the goal of a ground conductor. The ground conductor needs to have a low impedance path back to the distribution transformer. The purpose of the safety ground is that if you get a live to chassis fault it will sink the fault current in order to blow the breaker.Attaching a ground wire from a socket to the cable ground does not satisfy this purpose adequately. If the cable ground has its own ground rod, you now have the earth in your fault path, a highly undesirable configuration. If the cable is bonded to the electrical ground rod you are better, but now the shielding of your coax is in the fault path which is still not optimal.Attaching to the cold water pipe is similarly not suitable. At least the cold water pipe should be properly bonded to the electrical ground, and provide a low impedance path for fault currents. However, if there is a problem with the grounding of your water pipes -- which can easily happen if a section of pipe is replaced with PVC, a fault can electrify your plumbing.Really I wouldn't recommend either of these plans under any circumstances, and they are certainly illegal. They both carry the risk of making an unrelated part of the house dangerous, or increase the risk of an electrical fault leading to a fire because a fault current goes through a high impedance link. It would be better to just leave the outlet ungrounded.The myth that it is OK to use a copper water pipe for grounding probably originates from many people seeing ground wires attached to their water pipes. This is actually required, but the purpose is to provide a ground connection to the water pipes -- the idea is that if a live wire touches the copper, it needs a low impedance path back to the transformer without going through the ground rod. The wire going to the copper pipe is *not* (in a to-code installation) providing a ground connection for the electrical system, and is certainly not providing an alternate ground connection for outlets that don't have 3 conductor wiring going back to the distribution panel."
},
{
"post_id": "",
"author": "Computeruser",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 06:15:27 pm",
"content": ">>> Attaching to the cold water pipe is similarly not suitableWhen I have posted about \"cold water pipe\", I have referred to the water pipe inlet running through the ground into the basement through the concrete floor. I thought that was what PetrosA was referring to.Perhaps I misinterpret. However, using the cold water inlet as described is Code where I live and has been for decades.... C"
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 06:28:04 pm",
"content": "It is required to attach the electrical ground from your main distribution panel to the water pipe coming out of the ground. The purpose of this is to make sure that your plumbing is grounded. I don't think it is allowed to use this as your physical earth connection -- that requires a dedicated ground rod. I could be wrong about this, or it could be allowed in some jurisdictions and not others. However, you can never use a copper pipe of any sort to provide a ground connection to an outlet in lieu of a wire running back to the ground conductor at your main breaker where it is connected to the neutral line of the transformer."
},
{
"post_id": "",
"author": "SgtRock",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 05, 2011, 07:11:08 pm",
"content": "Dear Ejeffery:--I completely agree with your remarks. I have only one small quibble; You stated:\"Attaching a ground wire from a socket to the cable ground does not satisfy this purpose adequately.\"--I checked the thread carefully, and I cannot find this being advocated anywhere.--Imagine for a moment that you are a hapless resident of my neighborhood. You have a 1950s 2 wire (no ground) system. One day you buy a UPS. When you route the cable through the UPS the \"No Ground\" light stays off. When you do not route the cable through the UPS the \"No Ground\" light stays on. Assuming arguendo that you cannot call an electrician, what do you do? You have 3 choices; 1) Use the UPS and route the cable through it. 2) Use the UPS and do not route the cable through it. 3)Do not use UPS at all. What do you recommend?--BTW, in my neighborhood the BrightHouse cable ground is directly clamped to the Progress Energy ground wire at the meter box. When I was adding ground wires to my friend's house I tied everything back to that point, with some ground pegs and water pipes thrown in for good measure.--Thanks for the good advice. Your further comments are humbly solicited. Best RegardsClear Ether"
},
{
"post_id": "",
"author": "Computeruser",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 07:43:08 pm",
"content": ">>> It is required to attach the electrical ground from your main distribution panel to the water pipe coming out of the ground. The purpose of this is to make sure that your plumbing is grounded. I don't think it is allowed to use this as your physical earth connection -- that requires a dedicated ground rod. I could be wrong about this, or it could be allowed in some jurisdictions and not others.It is obviously dependent on jurisdiction. I have never had a separate ground rod in any of my residences. Thank you for your elaboration - I appreciated it. ... C"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 08:02:09 pm",
"content": "Quote from: Computeruser on September 05, 2011, 07:43:08 pmThe ground rod is not really visible so you would not know if it was there. The reason it is not generally permitted to use the metal piping as a ground point is you cannot know if the pipe makes a good earth connection once it disappears from view. In my house, for example, the mains water supply arrives in a plastic pipe and gets converted to copper once it enters the building. Even if the buried pipe is made of copper it may be in a protective sheath for corrosion resistance.The ground, or earth, connection is usually provided by the electricity company or house builder at the junction box where electricity enters the premises and this earth has an assurance of being a good earth. This is the earth you should use for electrical safety.As was mentioned above all metal piping in the house should be bonded to the main earth provided at the junction box, but this does not mean the metal piping is the source of the ground, it means the metal piping is grounded for safety."
},
{
"post_id": "",
"author": "Computeruser",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 08:41:43 pm",
"content": ">>> The ground rod is not really visible so you would not know if it was there. The reason it is not generally permitted to use the metal piping as a ground point is you cannot know if the pipe makes a good earth connection once it disappears from view.>>> In my house, for example, the mains water supply arrives in a plastic pipe and gets converted to copper once it enters the buildingThere really is lots of detail in all of this, isn't there?In my case, there may be a ground rod outside at the street, but the single and only ground wire at the panel in the basement connects to the incoming water pipe. I checked very carefully.I will soon get a chance to perhaps see what is outside because the city is going to replace the water distribution system. For certain, the large water pipes are plastic (or some composite). I should see the joins when they do this. We did have digging in the front (and back) yard to put in a sprinkler system and the company had diagrams and permissions for digging around water, gas and electrical conduit (all going out the front to the street).... C"
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 09:42:09 pm",
"content": "Quote from: SgtRock on September 05, 2011, 07:11:08 pmIt doesn't matter much. All three cases you have equipment that expects a 3-pin power connection with a safety ground run on an ungrounded circuit. In one option you have fooled the UPS into turning off the warning light, but you haven't actually fixed the problem. As long as you aren't connecting the cable with the purpose of making the warning go out, that is probably fine. I understood that the cable was being connected in order to 'provide a ground' for the UPS circuit -- and this is what I was saying was not effective. Which one is safer depends on the details of the wiring and what type of faults you are trying to protect against.QuoteAs in the incoming power to your distribution panel has only three wires (two live wires plus neutral, but not ground)? Also, does your house have a separate main disconnect switch upstream of your distribution panel? It could be inside or outside your house near the meter."
},
{
"post_id": "",
"author": "Kibi",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 05, 2011, 10:25:47 pm",
"content": "We used to live in an old house many years ago. When I say old, I mean properly old, it has a three phase supply as that was no uncommon back in those days. The wiring had been updated in the 50's, so it had proper steel conduit in the walls and ceilings, with proper PVC insulated wires running through them, not that cotton mesh type insulation from the 30's. Circuit breakers hadn't been invented before the upgrade, so the distribution board was still equipped with those nasty porcelain fuse cartridges which you had to reset by wiring a new piece of fuse wire between the contacts.Anyway, the important thing to note is that even after the wiring had been \"updated\", the house was still supplied with three phase.There had been a problem with the electricity bill, ZESA (Zimbabwe Electricity Supply Authority) said we hadn't paid for 6 months when we had. Soon enough a representative of ZESA arrived and said that he had to cut our electricity supply off until we had paid the bill. I call him a representative, because this guy was by no means an electrician. He removed the four main fuses on their side of the meter and took them away with him saying that he's bring them back and re-fit them once our bill was settled.It took a couple of days to resolve our problem with ZESA's head office. The representative returned whilst nobody was at home to re-fit our fuses. He left a note to say he'd been round return our electricity supply.We returned home that evening, saw the note and switched the light on which glowed extremely brightly and then gave up after a few seconds. Mmmm, that's odd. Perhaps they are supplying us with extra electricity to make up for the time we spent in the dark.The joke was short lived as other lights either didn't switch on at all or suffered the same fate as the first one. The fridge was running, but didn't sound too good, so it was promptly switched off at which point the kitchen light came on.I pulled the lead out of the kettle and put my meter across it's terminals to find about 380v registering on the it.Right, off to distribution board I go. A quick inspection revealed that the ZESA representative had only replaced three of the fuses that he'd taken away. One fuse was present in each of the five feeds, but the fuse in the neutral line missing!!!Brilliant work, so now the whole house is floating.The low impedance water heaters on one phase are allowing the other higher impedance appliances like lights to conduct through them phase to phase via the neutral line which is floating.After going through all the bureaucracy and procedures of such government organisations that ZESA is based on, we managed to get hold of the representative who has re-fitted the fuses. He was quite flippant about the fact that he had misplaced the fourth fuse whilst they were in his possession and thought he was doing us a favour by at least giving us back three of the four. Aren't we the lucky ones!He got quite aggressive when I tried to explain the basic principals of electricity and the methods of it's transmission and that it would have been better to at least put one of the fuses on the neutral line and we could have put up with just two phases and a few sections of the house not working at all rather than potentially burn the house down.To compound the issue, he's lost one of the 60A fuses that goes on one of the live phases. The 120A neural fuse was inserted in a live feed!Oh well, at least we are lucky that nobody was hurt."
},
{
"post_id": "",
"author": "Computeruser",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 05, 2011, 10:43:55 pm",
"content": "IanB wrote: The ground rod is not really visible so you would not know if it was thereejeffery wrote: As in the incoming power to your distribution panel has only three wires (two live wires plus neutral, but not ground)?On closer reflection and inspection, you are both correct. Thank you.Yes the three wires belong to the electric company, so the neutral is probably grounded somewhere where I cannot see it. Then there is a ground wire from the screw block on the input over to the water pipe coming out of the ground into my house.So I can see one ground, but I am now sure there is another one I cannot see.Thank you for all the information. ... C"
},
{
"post_id": "",
"author": "ejeffrey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 07, 2011, 02:04:53 pm",
"content": "QuoteYes, this is an all too common problem with 3-phase systems. Our laboratory had a problem where the jokers who call themselves electricians didn't screw down the neutral line to the main disconnect switch. It was very rigid, so it held against the contact by spring force, but eventually arced and heated until the copper became brittle and broke. All told we got off easy with only about 15,000 EUR worth of damages. Really, the neutral line should not be fused to begin with, and definitely shouldn't be fused in a 3-phase system exactly to reduce the chance of this sort of issue -- if it actually blows under normal operation it is more likely to leave the system less safe than before."
},
{
"post_id": "",
"author": "Bren",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "September 07, 2011, 07:16:44 pm",
"content": "Well, after reading all your posts, It sounds to me like an average occurrence of trying to deal with large scale electrical or telecommunication companies.You're better off banging your head against a wall."
},
{
"post_id": "",
"author": "SgtRock",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 09, 2011, 08:17:29 am",
"content": "Dear Ejeffery:--You stated:\"It doesn't matter much. All three cases you have equipment that expects a 3-pin power connection with a safety ground run on an ungrounded circuit. In one option you have fooled the UPS into turning off the warning light, but you haven't actually fixed the problem.\"--The reason I temporarily used the UPS was not so I could make the \"No Ground\" on the UPS go out, It was so the computer equipment would have a ground. And indeed it did, at least enough to keep it from floating. The computer blew sometime after the \"Cable Guy\" disconnected the UPS. Admittedly the sheathing of the cable would not protect against a high amperage short.\"As long as you aren't connecting the cable with the purpose of making the warning go out, that is probably fine. I understood that the cable was being connected in order to 'provide a ground' for the UPS circuit -- and this is what I was saying was not effective. Which one is safer depends on the details of the wiring and what type of faults you are trying to protect against.\"--You seem to have taken the position that I should not do something (even temporarily), and also the position that it makes no difference if I do it or not. You seem to have lost track of the fact that I grounded all of my neighbors sockets as soon as I could, and instead answered as if I was advocating using the cable sheath ground as a first and permanent solution.--Let me restate my point, briefly. My neighborhood has 1950s houses, 2 wire runs, and often as not 3 hole sockets (hooked up by dern fools). Failures of equipment containing microprocessors are frequent because of the floating ground situtation. I merely mentioned my neighbor's case because I thought it interesting, and to provoke discussion. I was not recommending that people try to ground the entire house by using the cable sheath. Best RegardsClear Ether"
},
{
"post_id": "",
"author": "saturation",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 09, 2011, 12:20:36 pm",
"content": "In the US, If you have an old house that still has old wiring and you own it, it would pay to rewire it professionally to electrical code rather than DIY.DIY is OK for a quick fix, but with surges and potential breaks in the neutral or ground lines due to storms or a bad branch circuit elsewhere or substandard wiring etc.,, the loss of your electronics or appliances often will cost more, not so much just to replace it, but the work you may be doing that require these appliances or the inconvenience of it.If you are buying an old house, have it inspected."
},
{
"post_id": "",
"author": "SgtRock",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 09, 2011, 01:51:08 pm",
"content": "Dear Saturation:--Very good advice. My neighbor is handicapped, and his wive is unemployed, so rewiring is out of the question. There are very few home owners in my neighborhood who can afford a full top to bottom rewire of their houses, right now.--As far a DIY goes, it is the only choice some folks have with regard to having a grounded outlet or not. Best RegardsClear Ether"
},
{
"post_id": "",
"author": "saturation",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 09, 2011, 03:37:39 pm",
"content": "Hello SgtRock,I'm sure your help was much appreciated, in that case DIY is better than not getting it done. They must have lived there for a very along time; if they buy appliances like washer dryers, they have unusual plugs that will need to disassembled and adapted to pre-code wiring. Today, not only is the labor more costly, but the cost of copper wires has appreciated a lot both with the housing boom of the early 2000s and the consumption from China.Quote from: SgtRock on September 09, 2011, 01:51:08 pm"
}
] |
2025-10-17T20:38:25.263430
| 22
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1970s-tv-transformer-as-an-isolation-transformer/
|
1970s TV transformer as an isolation transformer - Page 1
|
[
{
"post_id": "",
"author": "lordvader88",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 21, 2017, 10:31:22 pm",
"content": "Its from a big floor model, with transistors and even a view ICs, I scrapped it, too bad it was smashed, its pretty hard to find old electronics where I live.I checked the winding on Ohms an found 4 sets and even separated out the 2'ndry in order.With 120V in on a solid black pair of wires, , on the main secondary set I get0V145V220248253274350or 0V,76,97,102,130,205Then there's a winding with 115V on it, its resistance was about 0.34Ohm. It has 2 grey wires. The Blk pair had 5.6O and I put mains 120V on on its winding.Does the black sound more like Primary ?Then on a separate sec.wind. there's 5.5V , I assume the CRT heater windingThere was another little transformer in this TV, 120V to 5.7V. so I assume thats run of that gray pair of 115V ? and is an audio transformer I guess.I don't have the schematic tho, but that sounds like the gray winding is only for small power for audio output, and not suitable above say 5-10W ? IDKSo for now I could use 102V (or well what ever combo) and try to power up a small vacuum tube radioSo this thing with some variac and switches and light blub limiter should work great"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 21, 2017, 10:39:25 pm",
"content": "You shouldn't rely on it to provide any protection against electric shock."
},
{
"post_id": "",
"author": "Electro Detective",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 21, 2017, 10:49:37 pm",
"content": "If you are going to play with it, make sure the 120v to 115-120v is truly isolated,and work out how much current it can safely deliver without cooking the transformerSuggest an inline fuse/s on primary and secondary for cheap insurance"
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 22, 2017, 01:17:13 am",
"content": "I echo the previous comments with one highlight:As well as having some age to it, such a transformer was never designed to be a true isolation transformer for a workbench. It may not have the same level of protection as a purpose-built one.The second thing is, you should never treat an isolation transformer as a \"magical\" solution to make working on any equipment \"safe\". Unless you know what you are doing, you can actually make the situation more dangerous - because some of the dangers will be less obvious.It is my belief that using an isolation transformer should only be when youknowyou need one - notthink, butknow... and if you do head down that road, do your homework. This includes finding out what can go wrong when using one."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 22, 2017, 06:01:51 am",
"content": "Quote from: Brumby on September 22, 2017, 01:17:13 amTransformer design is a mature technology, they worked out insulation ratings & so on, decades ago, so such a transformer, in good condition, is unlikely to break down causing injury or damage.That said, transformersdofail, & you need to be aware of that.As a TV transformer, its output current may be less than you require.The old BW TV ones in Oz were rated at around 300mA from the main 300v (or so) HT winding."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 22, 2017, 06:27:06 am",
"content": "Quote from: vk6zgo on September 22, 2017, 06:01:51 amWhile I do not dispute what you are saying, I would like to point out we are not just talking about technology that was mature decades ago - but of a unit that was built decades ago with materials from decades ago and pressed into service decades ago.As long as there wasn't a cheap-skate manufacturer who built the TV with a transformer on the edge of its ratings, then there should be a reasonable expectation on its performance - but you can't treat it as new.QuoteDefinitely. Be aware."
},
{
"post_id": "",
"author": "lordvader88",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 23, 2017, 01:34:57 am",
"content": "Its from a Zenith Chroma Deluxe 2 floor version, I have the CRT tube sticker, but I'm not actually sure what model the TV is. I'm still not sure the average Wattage of similar TVs from back then.My DC resistance measurements, and voltages and calculations of the few equations I know of this matches up on the little 20:1 transformer.From about 1mA to 100mA its 2nd voltage drops from 7 to 5.3V and the power goes from whatever low up to +1/2W with 5.3V*100mA. That was with 50OhmImpedance reflections for equivalent circuits, just learned of that last night...I know 2-3-4yr university maths of for some stuff so thats no problem.................if/once I learn the eq/remember itI have not tested loads on the big tran's yet...........since I don't know the little one yet (and surely better too leanr on it)I have almost nothing to hook up to this yet anyway that needs it.So yup generally black wires on a trans. of the era before SMPS are the mains.So I have a 3-prong ATX plug, and this thing only has 1 primary winding, and no taps. Someone I trust said its fine to solder the solder the earth 3rd prong wire/nut bolt hole thing??? and bolt it to the transformer chassis.So thats what I'll do unless I'm missing something"
}
] |
2025-10-17T18:48:19.718811
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1975-tmk-electronic-tester-model-117/
|
1975 TMK Electronic Tester model 117 - Page 1
|
[
{
"post_id": "",
"author": "Hammer_651",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 23, 2024, 02:13:25 am",
"content": "Hi all. I have this older multi-meter a TMK Electronic Tester Model-117 (see pic) as it's called and i have now found a burnt rotary switch PCB. I would like to find another one but I don't like my chances as I think it may have been a kit project. Maybe someone out there may have an old one or a damaged one for parts. Does anyone know if these PCB's can be repaired or should I just get a new PCB made?I do know about electronics and a student in the same. This is a restore project for me so if anyone can help it would be appreciated.Thanks."
},
{
"post_id": "",
"author": "coromonadalix",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 23, 2024, 02:08:03 pm",
"content": "internals pictures and close ups would help"
},
{
"post_id": "",
"author": "Hammer_651",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 26, 2024, 04:26:58 am",
"content": "Hi. I think a polite g/day would also help when replying. Attached is a pic of the rotary switch PCB. The previous owner did some work on it and I would like to restore it to a better state.Hammer_651"
},
{
"post_id": "",
"author": "squadchannel",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 26, 2024, 05:08:29 am",
"content": "The image appears to be corrupted, but I was able to view it in GIMP.does not need to be made a circuit board. It is completely repairable.Just repair the red-penned area with tinned copper wire."
},
{
"post_id": "",
"author": "Hammer_651",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 26, 2024, 06:47:52 am",
"content": "Hello. Thanks for5 the reply I'll give it a go with the help of youtube.H."
},
{
"post_id": "",
"author": "squadchannel",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 26, 2024, 06:52:07 am",
"content": "mark's video would be helpful."
},
{
"post_id": "",
"author": "Poroit",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 26, 2024, 08:43:31 am",
"content": "G'day Hammer,Check the meter movement is OK first up before you start any other repairs.Heaps of videos on Youtube which show you how."
}
] |
2025-10-17T16:30:01.788336
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1976-airplane-motor-filter-how-much-does-ferrite-bead-effect-this-circuit/
|
1976 airplane motor filter, how much does ferrite bead effect this circuit? - Page 1
|
[
{
"post_id": "",
"author": "NaDobraNich",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 20, 2024, 09:08:21 pm",
"content": "I have parts from a 1975 light aircraft, heater blower motor is 24VDC. Has this \"electronics plate\" between it and the plane.See diagram.I can't find a part number for the ferrite, but I think it can only be a ferrite because the screw terminal goes completely through it.What I'm trying to figure out is why in the 1960s when they were designing this plane, did they put the 2.2uF axial 13mm diameter caps in this config?The signal isn't changed with the ferrites, just the EMI right? So why make a big steel plate with the caps on it in what I had figured was an input/output \"side\"?Also... The motor is blown. Is it likely that a new mfg motor would need this same config?- I know none of what I think is airplane advice, just doing the research for the person that will eventually fix and sign off on it."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2024, 09:20:54 pm",
"content": "Pictures would help."
},
{
"post_id": "",
"author": "jpanhalt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2024, 09:29:31 pm",
"content": "1970's light aircraft of 1960's design with 24V supply in North America. Is it a light twin? That cannot be the original schematic. Are you sure of the schematic? If it is a Beechcraft (e.g., Baron series), I may have the manual, or is that copied from the original manual."
},
{
"post_id": "",
"author": "NaDobraNich",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 20, 2024, 10:18:06 pm",
"content": "Not a Beechcraft.It's a PC6.Of course it isn't the original schematic. I just took it apart and measured it. Picture posted."
},
{
"post_id": "",
"author": "Postal2",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 20, 2024, 10:50:25 pm",
"content": "Quote from: NaDobraNich on June 20, 2024, 09:08:21 pmI have ferrite beads for this. This is a special ferrite, the key difference is that ferrite conducts current like metal, but looks like regular ferrite. I assume very big magnetic permeability. Can also be used to suppress the noise of a 50Hz thyristor circuit."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 20, 2024, 11:04:02 pm",
"content": "My guess is to suppress the considerable noise from the brushes which would otherwise interfere with the AM aircraft band."
},
{
"post_id": "",
"author": "NaDobraNich",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 20, 2024, 11:44:08 pm",
"content": "Quote from: David Hess on June 20, 2024, 11:04:02 pmThat is what I figured.I'm just not sure if it would be as required with a modern blower motor. Or if this contraption could be modernized a bit to be smaller/lighter/cheaper and more effective at the same time.The USED blower motor quote I have is $6000. It's a completely average 24VDC motor.... Airplanes, man."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 21, 2024, 03:44:41 am",
"content": "Yeah, that's pretty normal, brushes make hella arcing noise, not something you can have with your radios, especially LW RDF. Even voice can be affected (>100MHz), sparking really goes up there.Here's another example from my bin:Not at all uncommon to see a small PCB here with just a couple caps, maybe ferrite beads, and mating the terminals to a cable, nothing more.Tim"
},
{
"post_id": "",
"author": "jpanhalt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 21, 2024, 09:04:51 am",
"content": "I have no experience servicing turbines. Single-engine (recip) in the US were usually 12V . The PC-6 is a pretty good sized airplane. (10,500#) and still qualifies as \"light.\" Janitrol was a popular brand of heater used in the twins I have seen. Here's a link to its service manual from a little later:https://www.csobeech.com/files/Janitrol-MaintenanceManual.pdfThat's just FYI.Anyway, as others have mentioned, noise suppression filters are used on every motor and other potential sources of noise."
},
{
"post_id": "",
"author": "NaDobraNich",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 21, 2024, 06:50:31 pm",
"content": "All good info.I guess something I'm still not clear on, is do those two caps make a difference where they are?Is this really just decoupling with 4-4.4uF (they are 2.2uF each, but measure 2.01)?Or does it matter that 2 are before the ferrites, and two are after?Is there any benefit to the + and - lines both having separate ferrites compared to being in a shielded cable with a single ferrite?Twisted pair helpful?"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 22, 2024, 12:26:41 am",
"content": "I would suggest maintaining or reproducing the mechanical assembly, including the general layout of conductors and grounds, component placement and value, and preferably component size. (Similar component lead + body length will matter more than identical size. Most likely, smaller is better anyway, but I would further air on the side of similar, rather than risking improvements, for something my life depends on.)Capacitors before and after, matters.Ferrite type, matters. Most ferrites, even of that size, saturate with a few amperes running through them; saturation means the AC impedance drops considerably. Not clear what type they have here, or if they're just kind of letting it happen and not caring, but reproducing that behavior would demand replacing them with equivalents; but good luck identifying it without drawings.A shielded cable, with the shield tied to the motor housing, would be one way to confine brush noise. A differential filter is still required to eliminate noise conducted within the cable. A shielded cable could not be isolated, though. It's not clear to me whether this is a metal-chassis environment (like a typical automotive scenario) or if other practices or standards apply. The single wires may suggest they could be wired in either order, or that the electrical system is isolated or elevated in some way from the chassis, or that no chassis is available to matter (fiberglass hull?), which will all affect the ideal design of a filter.Even for the two-line case, some capacitance to the motor housing (and probably by extension, ground/chassis) would probably help for reducing common mode noise, and maybe additional ferrites (both wires, common mode) or a choke proper would be used as well. But again, it all depends on the setup.Tim"
}
] |
2025-10-17T16:33:50.887304
| 11
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1990-olypmus-video-light-source-noxious-smell/
|
1990 Olypmus Video Light Source - Noxious Smell - Page 1
|
[
{
"post_id": "",
"author": "K1JOS",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 22, 2014, 03:51:51 am",
"content": "I came upon a new appearing Olympus video-endoscope lightsource that I would like to use as a bore-scope. Only problem is after a few minutes a really nauseating stink comes from the PSU fan. Not your classic burn resistor, plastic but something I would expect (though never experienced) from that described for selenium rectifers that have become zapped. I have looked over the chassis and it looks virtually new, no dust, no dead bugs, and no bulging or leaking lytics but it is definitely coming from the power supply PCB. Should I just replace the 6 or so lytics or is there some other 1990 vintage culprit known to smell this bad?thanksjerry"
},
{
"post_id": "",
"author": "Shock",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 22, 2014, 05:18:41 am",
"content": "If not caps, transistor, rotting rubber or plastic, or perhaps mice used to read the newspaper in there."
},
{
"post_id": "",
"author": "lapm",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 22, 2014, 08:11:30 am",
"content": "1990 electrolytics? I would change them to new ones. Thats 24 years of service life all ready. Very respectfull for any electrolytics.While capacitors are out, you might consider use some sort of electronics cleaning spray or something, just in case of above mentioned reason..."
},
{
"post_id": "",
"author": "Yago",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 22, 2014, 08:18:17 am",
"content": "Quote from: Shock on March 22, 2014, 05:18:41 amHehe good one Shock"
}
] |
2025-10-17T20:05:44.031426
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/19th-century-spectrum-analyzer-and-oscilloscope/
|
19th century spectrum analyzer and oscilloscope - Page 1
|
[
{
"post_id": "",
"author": "pplaninsky",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 03, 2015, 10:28:56 am",
"content": "when you see this - you can really grasp the ideas of harmonics, time base, volts per division, dc offsetall done with mechanics and gears, so you actually see it.rest of the series"
},
{
"post_id": "",
"author": "Vgkid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 03, 2015, 05:53:20 pm",
"content": "That is very cool, just started watching them."
},
{
"post_id": "",
"author": "Tom45",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 03, 2015, 11:17:48 pm",
"content": "The science museum in London has an extensive display of 19th century mechanical devices like this. When I visited, I only had time to marvel at them, but not understand their working principles.This series of videos does a great job of showing the theory and practice of one such class of mechanical marvel that I saw at the museum.Thanks for finding this."
},
{
"post_id": "",
"author": "pplaninsky",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 09, 2015, 02:38:58 pm",
"content": "You are most welcome!I enjoyed these videos very much as well."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 09, 2015, 04:18:35 pm",
"content": "Also check out the classic \"On the sensations of tone...\" by Hermann Helmholtz (1863), still available in a classic English translation on Dover:http://www.amazon.com/Sensations-Tone-Dover-Books-Music/dp/0486607534.He synthesized musical notes with an ensemble of tuning forks (at integer harmonics of the fundamental fork), synchronized to a master fork (with a needle dipping into a mercury cup) that drove electromagnets at each fork. In turn, each fork had its own Helmholtz resonator with a variable aperture to adjust the amplitude. By detuning the resonators, he was able to demonstrate that the audible result was not sensitive to relative phase of the harmonics.He was able to synthesize German vowels, which was more than my college German teacher could get me to do accurately."
}
] |
2025-10-17T19:32:21.652876
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/19v-psu-charging-12v-lead-acid-battery/
|
19V PSU charging 12V lead acid battery - Page 1
|
[
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 16, 2019, 04:20:09 pm",
"content": "Is it ok to charge lead acid battery by PWM controlled circuit powered by 19V PSU? (no typical step-down circuitry, such as inductor/capacitor, just MOSFET switching voltage on/off).I plan to measure the voltage on the battery using the ADC + resistor divider, and increase the duty cycle until the voltage does not exceed the allowable for this type of battery.Of course I will use PSU with soft overcurrent protection, such way i wont exceed allowed charging current."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 05:22:54 pm",
"content": "Just one question: why?A power supply with overcurrent protection, will likely not be designed to operate in constant current mode. The actual current limit could be higher than the rating and it much simply shut down, when it's exceeded, rather than regulating the current.You need a constant current power supply for this to work properly, but it also needs to safely work open circuit. An LED driver might be more suitable, but why not simply buy a lead acid battery charger in the first place?"
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 16, 2019, 05:39:08 pm",
"content": "You're right, I'd rather make an additional discrete circuit to limit the charging current pulse. I just fear that even in a PWM mode, in a short pulse (the average current will not exceed the maximum) high momentary current will cause some harm to the battery...Reason of such strange solution - 3rd world country problems, mostly.I'm not looking for a way to make an efficient charger, but i hoped PWM will be a little better than a heater in the form of a linear adjustable regulator (like it is done in cheap APC UPS).The end device is customizable DC UPS + load control, it is based on ESP8266, so most of parameters will be adjusted in software.Since probably underqualified electricians will install it, i am trying to make the device as simple as possible. Unfortunately LEGO from different modules will not work in such case.A maximum of three connectors, a battery (protection against reverse polarity), a power supply (barrel jack wont allow such mistake), and load (barrel plug, no mistake possible as well).One of the requirements to the device - inexpensive. Existing devices are excellent electronic waste generators, with lithium batteries that sometimes explode, and often just die very early, additionally there is no supply of good quality lithium batteries in this country.I want to make a device that will work with an available common power supplies and an affordable, replaceable lead-acid battery (lead-acid batteries are recycled here). Maybe it will be some 9V supply + 6V battery. Or laptop power supply (19V mostly) and 12V battery."
},
{
"post_id": "",
"author": "AVGresponding",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 06:13:02 pm",
"content": "Perhaps a small automotive lamp in series with the PSU output?More information would be helpful, like the output current of the PSU, the type of lead acid battery (wet, gel etc) and its capacity"
},
{
"post_id": "",
"author": "KL27x",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 06:18:45 pm",
"content": "I say why not?With the battery on there, you have a buck converter, essentially. Car battery is not picky. As long as the PSU handles it, I don't see any problem."
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 16, 2019, 06:26:30 pm",
"content": "Quote from: ThickPhilM on September 16, 2019, 06:13:02 pmLamp is worse than adjustable linear regulatorLet's assume PSU current is sufficient in any case, i dropped idea relying on PSU current limit.Most likely not smaller than 12V 2.6Ah gel, this means with max 0.1C it should be 0.26A. As i charge by PWM, probably in pulse i can use 0.2C (if i wont exceed 50% duty cycle). I plan to implement it by using typical 2 NPN transistor circuit.But thats the question, if battery chemistry is ok with fact, that on 10-20khz PWM pulse current is 0.2C, but average current is 0.1C."
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 16, 2019, 06:27:24 pm",
"content": "Quote from: KL27x on September 16, 2019, 06:18:45 pmIt's not car battery, small UPS gel battery, they look awful if they start gassing"
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 07:04:23 pm",
"content": "Quote from: KL27x on September 16, 2019, 06:18:45 pmCertainly not a buck. As far as a 19V PSU is concerned, the battery across its output is a dead short. It will dump its maximum output current into it. The output capacitors will rapidly discharge when the switched is turned on, possibly shortening their life after many such cycles.If the PSU is crap, it may even overheat if it permits more than its maximum allowable current to be drawn in peaks. 2A at 50% duty cycle is more heat than constant 1A.Quote from: nuclearcat on September 16, 2019, 06:26:30 pmNo such thingThe PSU will output the maximum current it can, unless battery ESR limits it (probably not).Don't like that? Add a choke in series with the battery. And a diode, like in buck converters. If inductance and PWM frequency are high enough, current will be smoothed into almost DC."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 07:07:37 pm",
"content": "Quote from: KL27x on September 16, 2019, 06:18:45 pmBut it isn't a buck converter, until you at least add an inductor, which is a very important part of a buck converter.An inductor limits the current, when the transistor is on and keeps the current flowing, when it's off. Without it, the current will only be limited by the power supply and no current will flow, when the transistor turns off. He wants to use a current limited power supply, presumably one with a constant current mode, which will definitely work, but a generic off the shelf power supply won't be guaranteed to behave in this manner.https://en.wikipedia.org/wiki/Buck_converterhttp://rohmfs.rohm.com/en/products/databook/applinote/ic/power/switching_regulator/inductor_calculation_appli-e.pdfhttp://www.ti.com/lit/an/slva477b/slva477b.pdfAn inductor and a diode is all that's required to turn this circuit into a buck converter. There doesn't need to be a capacitor, because the battery will act as one, although a small capacitor would be a good idea."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 07:19:52 pm",
"content": "I have a PFC choke harvested from an ATX power supply which is about 1mH and capable of a few amps. Hopefully that's typical for similar chokes.19V-12V is 7V across the choke and therefore 7A/ms rise of current during on time, 12A/ms fall during off time. With 100kHz PWM that seems like it ought to be less than 100mA ripple (too lazy to do exact math).editOr, dunno, just get a PSU which current-limits at about 0.5A into 12V (to be determined empirically) and you will get the kind of pulsed waveform you initially wanted, averaging to 0.25A. I don't know how it affects battery chemistry, though."
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 16, 2019, 08:03:03 pm",
"content": "Quote from: magic on September 16, 2019, 07:19:52 pmIt seems i will buy some small batteries, lock them in explosive-proof container with ventilation, and will do tests in extreme modes. I think its best way to know."
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 16, 2019, 08:09:55 pm",
"content": "Quote from: KL27x on September 16, 2019, 06:18:45 pmIt's as far as you can get from buck converter. You are shorting charged capacitor into battery with very low internal resistance. If this somehow works and pass element for PWM won't fail due to very high peak current, then output capacitor of PSU will certainly fail after some time due to extreme ripple current."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 08:46:18 pm",
"content": "Another option: just screw PWM altogether.Low power 12V PSU bricks are common everywhere. Find one with 250mA max current, then it's a matter of changing or adding one resistor to increase its target output voltage to 14V. Then as long as battery voltage is less than the target, the PSU will just keep charging with its maximum current."
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 16, 2019, 08:48:08 pm",
"content": "Quote from: magic on September 16, 2019, 08:46:18 pmGood option as well, thanks for idea."
},
{
"post_id": "",
"author": "KL27x",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 08:50:26 pm",
"content": "QuoteOk, geniuses.You've gone this far. Add the frigging inductor. In this case you don't even need an inductor. Just a power resistor in series. Done.Battery is your Q. Add resistor. You have a low pass filter and the power resistor drops most all the excess voltage. As I said, as long as the PSU is happy to provide the juice, you're good.Is there another way to do it? Yeah. Is it better? No. This is a perfectly adequate and perfectly sensible way to charge a lead acid battery, if you desire to have voltage sensing/cutoff and adjustable control over max current and you already have a 19V PSU on your hands. (IMO). If efficiency is important, you could build or buy a proper buck converter with inductor."
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 16, 2019, 08:52:32 pm",
"content": "Quote from: KL27x on September 16, 2019, 08:50:26 pmProbably this circuit will generate less heat:"
},
{
"post_id": "",
"author": "mikerj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 16, 2019, 10:13:43 pm",
"content": "Quote from: KL27x on September 16, 2019, 08:50:26 pmThe point being made was that a buck converter requires an inductor. Adding a resistor to limit current defeats the point of using PWM in the first place.What do you mean by \"Battery is your Q\"? Lead acid batteries are not particularly inductive, what am I overlooking?"
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 06:24:53 am",
"content": "Quote from: nuclearcat on September 16, 2019, 08:52:32 pmThat's a constant current source? Nope, it's a linear regulator which will generate exactly as much heat as any other linear regulator: 7V times charging current."
},
{
"post_id": "",
"author": "KL27x",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 06:28:09 am",
"content": "QuoteNo it doesn't defeat the purpose; the purpose being to safely charge a lead acid battery. It means you can adjust/limit the current, and without needing a full voltage regulator. I somehow doubt he is concerned with efficiency. The resistor is not there to limit the current to the battery. The resistor is there to drop the excess voltage that someone correctly complained is going to wreck the PSU. It's there to limit the current to the max of the PSU, say (19V-10V)/(MAX PSU Amps) =R. The PWM is to adjust the current to the battery.You got your power source sorted out with a single power resistor, and now you can get on with charging your battery using your ADC/comparator and micro/logic circuitry and output FET. You can tweak the max current settings for any size lead acid battery you want. You can set it to automatically throttle back to keep the voltage of the battery at 13.8V once it reaches that mark.QuoteYeah, you're right. I mean to say \"C\" not \"Q.\" Brain fart.If adding a resistor defeats the purpose of PWM, then every LED that is PWM'd is \"defeating the purpose,\" since it also needs current limiting or some sort to avoid shorting the power supply. The PWM gives the ability to turn down the current."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 06:33:38 am",
"content": "Quote from: KL27x on September 17, 2019, 06:28:09 amIt doesIt's the first time I see anybody call resistive dropper a \"buck converter\".Buck converter is that thingy with a coil, a power switch and a rectifier."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 07:59:32 am",
"content": "Quote from: nuclearcat on September 16, 2019, 08:52:32 pmIf you don't mind a linear regulator, then how about the LM317?"
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 17, 2019, 08:58:25 am",
"content": "Quote from: Zero999 on September 17, 2019, 07:59:32 amIt will work too, but probably i will check if feasible to use regulator to charge in CV mode, a bit different circuit, and i have to check if i can offset Vadj from MCU, as its better to charge a bit faster empty battery (maybe PWM + RC + opamp?)."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 09:10:10 am",
"content": "Quote from: nuclearcat on September 17, 2019, 08:58:25 amThe idea is to keep the current constant and turn it off, when the battery voltage rises too high."
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 17, 2019, 11:47:51 am",
"content": "Quote from: Zero999 on September 17, 2019, 09:10:10 amI am planning to measure battery idle voltage and probably apply higher current if state of charge is low. Also it will be nice if i can adjust offset, according to temperature and battery capacity (including approximating capacity loss with age). Its cheap to do, make charging faster (outages too frequency in my country to charge slowest way), and will increase lifespan of battery."
},
{
"post_id": "",
"author": "AVGresponding",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 05:26:43 pm",
"content": "Quote from: nuclearcat on September 16, 2019, 06:26:30 pmWell, I was making a couple of guesses based on your previous posts, ie that you were looking for lowest complexity due to 'third world issues', and that you were using small car or motorbike wet lead acid batteries.Now that I know you're using very small gel types, that changes things significantly.Gel aka AGM type lead acid batteries really don't like over-voltage situations, especially very small ones, and doubly especially the likely low quality ones you'll be using, which will have a lot of very impure recycled lead in the plates. Do not use a pwm regulated 19v supply, you will kill the battery in a year or so, depending on a couple of other things (ambient temperature, depth of cycling).Cyclic charging of these batteries requires a constant current for the bulk charge, and a constant voltage for equalisation. PWM charging from a 19v source is not a good idea, a simple linear regulator and current limiting resistor are the best bet for such small batteries. A laptop charger is massive overkill.C/2 is more than adequate for the bulk charge in this case, exceed C and youwillcook it. Float current shouldn't be more than a few tens of milliamps at most, if it draws more, it's on its way out.Do not believe the manufacturers datasheets on charge voltages; they want to sell you more batteries.If you want a good lifespan, a float charge voltage 13.6v really is the highest you should go, cyclic use, 13.8v, but don't let it sit at that voltage for more than a couple of hours.The quality of these batteries varies considerably. Cheap Chinese ones are not very different from cheap Chinese NiMH in their capacity claims in my experience; adjust your bulk charge rates accordingly.With reasonable ambient temperatures, and sympathetic charge/discharge profiles, I've had good quality batteries last 20 years.I've also seen good quality batteries cooked in months, by crappy quality/badly adjusted chargers. Some of the bigger ones can be quite exciting when they fail"
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 17, 2019, 05:45:13 pm",
"content": "Quote from: ThickPhilM on September 17, 2019, 05:26:43 pmThank you very much for the detailed advice!!!Most likely I will go this way, bulk charge stage C/2 (max) or even less current, depending on the remaining battery capacity and temperature, and static CV, 13.6V for equalizing charge.Probably i will not do it simplest way, as little bit more components will increase a lot efficiency and reliability of solution.I will use ADC from ESP8266 to measure battery voltage, one pin to enable topping charge, and1) I2S/PWM for current offset over RC, to LM317.or2) I2S/PWM driving crude step-down buck converter (which is more preferable, as more efficient, but probably more tricky to implement)I am considering also to shift measurement range from 0-14V to 12-14V by using inverting opamp with virtual ground at 12V, but probably better to open separate topic for that."
},
{
"post_id": "",
"author": "iMo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 07:33:16 pm",
"content": "I would go with RPi 4 (4GB ram), LTZ1000 as the Vref, double ovenized OCXO for precise PWM, LTC2500-32 ADC, 0.001% 0.1ppm/C shunt. Your lead acid battery will be pretty happy then"
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 08:22:41 pm",
"content": "But the lead acid battery tempco is -3.3mV to -6.7mV/°C/cell ... it goes in the oven too?I think a car battery charger with Wi-Fi is useful, you can remotely check up on it instead of walking back and forth to the garage. Lowest cost would be to mod the 19V laptop adapter to put out less, say 14V or whatever an MCU commands with PWM, but that is beyond a beginner's project. A PWM controller buck-converter or linear regulator might be something basic to add after the 19V PSU.ESP8266 has a crappy A/D, not good enough here. Noisy, non-linear 10-bit 0-1V input range, poor accuracy you need to calibrate it and have to shut off the RF TX circuit to get a reasonable reading. I thought the internal 1V reference does poor over temperature too but can't find that correction graph.https://www.espressif.com/en/support/download/documents"
},
{
"post_id": "",
"author": "iMo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 09:30:37 pm",
"content": "Here is the simplest CC CV charger I saw somewhere in past.And it works, I've been using it from time to time (nimh, lion).Use it at your own riskPS:I_charging = 1.25V / R1 [A, ohm] max 1A, LM317 likes a small heatsink, R1 2-3WVbat = (R2+R3)/R3 * 2.5V TL431 trips at aprox 2.500V"
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 17, 2019, 11:26:38 pm",
"content": "Quote from: floobydust on September 17, 2019, 08:22:41 pmPurpose of device is a bit different. I am living in country where government supplied electricity lasts max 12-18hours per day, when it go off, in some households private generator supply kicks in (still, it takes 30-60 seconds, enough to reboot router or DSL modem), or if it is less fortunate people - they stay in dark. Sometimes electricity supply is very unstable and might go on/off tens of times per day. Regular offline UPS doesn't last long, too much conversion losses, and need some hacking (hacking away buzzer, hehe).This device will be connected in the middle, between AC/DC SMPS and wifi router, to provide continuous supply, so at least people can stay online from their mobiles. Most of routers is OK with 14V (step-down buck inside, only problem sometimes caps max voltage on DC IN), but on some old routers i seen LDO, there i i can use cheap LM2596 step-down brick.ESP8266 will keep an eye on battery voltage, and if it is too low, send data to cloud/owner mobile, cut off router, lower power usage as much as possible (disable RF) until mains appears, and then if still no supply, next level go to deep sleep and wake each 5 minute, to check if power appeared. It will be easy to implement additional functions, battery health monitoring, remaining runtime, programming some router cut-off for night time and etc.I am considering to make it OSHW, if it will work fine."
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 17, 2019, 11:49:31 pm",
"content": "Also see:https://www.eevblog.com/forum/beginners/bench-power-supply-battery-charging-circuit/"
},
{
"post_id": "",
"author": "nuclearcat",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "September 18, 2019, 05:30:26 am",
"content": "Quote from: floobydust on September 17, 2019, 08:22:41 pmThat make me wonder if it is better to add some $1 STM32F0/F1, simplify some circuits and have more measurement points (current + voltage, proper PWM, sleep modes, etc).Seems ESP8266 is not great for anything than very generic MCU jobs and as wifi bridge."
}
] |
2025-10-17T18:03:30.037181
| 32
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1f-capacitors-discharge-rate/
|
1F capacitors discharge rate - Page 1
|
[
{
"post_id": "",
"author": "Salmannm94",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 03, 2016, 12:44:18 am",
"content": "I have been experimenting with different capacitors to test their charge/discharge rate. While doing that I noticed something weird. I have a 1F 5.5V capacitor that I charged to about 4.4V and then connected it directly to a LED to discharge it. I was expecting that capacitor to discharge quickly since the LED has negligible resistance (hence small time constant), but it actually lasted for about a minute. Does anyone have an explanation for this?!"
},
{
"post_id": "",
"author": "ebclr",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2016, 12:55:18 am",
"content": "\" LED has negligible resistance \"Well , a typical led need 2.7V and 20 ma, by Ohm's Law will have a Req of 135 ohm at that voltage and tension, This is not so small as you may think. also with 4.4V and 1 Farad you are killing you Led live expectancy, because you are forcing a much higher current than specified powering with 4.4 V initialy"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2016, 03:42:59 am",
"content": "Don't use a LED for this. The LED is a very non-linear load, its behaviour changes radically around its \"forward voltage\" Vfparameter. Above its rated Vfit will have seemingly low resistance. As the applied voltage drops to close to the rated Vfits effective resistance will increase, becoming very high when the applied voltage is below the Vfparameter. So it is a poor choice for determining capacitor discharge curves, as you will be seeing more of the behaviour of the LED than of the capacitor.You need to use a purely resistive and linear load, like a simple resistor. It would be an instructive exercise to use an oscilloscope to monitor the voltage on the capacitor as you \"short\" the cap through resistors of different values. Each resistor value will give you a different discharge voltage curve as seen on the scope. This experiment will show you graphically what is meant by the \"time constant\".https://en.wikipedia.org/wiki/RC_time_constant"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 03, 2016, 07:55:54 am",
"content": "Quote from: Salmannm94 on August 03, 2016, 12:44:18 amWhat sort of 1F capacitor is it?If it's a memory back up capacitor, then this should be expected, as it will have an effective series resistance of 100R or more."
},
{
"post_id": "",
"author": "Salmannm94",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 03, 2016, 04:44:11 pm",
"content": "Quote from: Hero999 on August 03, 2016, 07:55:54 amI looked it up, and it's actually a double-layer memory back up capacitor. I had no idea that they can have internal resistance this high"
}
] |
2025-10-17T19:14:27.746573
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1g74-and-2g74-different/
|
1G74 and 2G74 different - Page 1
|
[
{
"post_id": "",
"author": "diyinhk",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 19, 2014, 08:19:16 am",
"content": "http://www.mouser.com/ds/2/302/74LVC2G74-352817.pdfhttp://www.mouser.com/ds/2/302/74LVC1G74-350009.pdfI cannot figure out the different from the datasheet.is it the same part and the different part number is due to history reason"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 19, 2014, 08:02:55 pm",
"content": "Idunno, but the markings are even the same...Tim"
},
{
"post_id": "",
"author": "CarlG",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "July 19, 2014, 08:46:46 pm",
"content": "I can't find any difference between the NXP '1G74 vs. '2G74 datasheets either, but the TI corresponding datasheets show some differencies. E g TI '1G74 is only specified at 3.3 and 5V for -40 to +125, and for some packages not recommended at all for that temp range.My guess is that NXP supplies the '1G74 as a 2nd source for TI. TI and NXP have had some sort of mutual \"2nd source agreement\" on std logic; however I don't now if that't the case anymore.The LVC/ALVC nomenclature is a bit confusing since some parts' '1Gxx refers to \"1st generation\" while other refers to \"single gate\" (and '2Gxx to \"2nd generation\" and \"dual gate\", respectively)."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 19, 2014, 10:40:04 pm",
"content": "I always thought it was package size or gate count, i.e., it's a single gate but in a 2G (TSSOP8 or whichever others) package. But something like a 3G14 is in the same package because it's counting gates.Not that it has to be consistent. Numbers are inconsistent all over the damn place. Look at the x86 instruction set...Tim"
}
] |
2025-10-17T19:58:36.060673
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1gb-rj45-pinout-(with-magnets)/
|
1Gb RJ45 pinout (with magnets) - Page 1
|
[
{
"post_id": "",
"author": "sw_guy",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 08, 2024, 02:06:59 pm",
"content": "There are a few variations of RJ45 connectors (with magnets). This is mainly about the center tap line. I am not sure how to connect P1 and P10. I can see that on some connectors P10 is connected to GND and P1 to GND thru 10nF capacitor. Does this apply to this RJ45 connector as well?Thanks in advance!"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2024, 02:32:13 pm",
"content": "From what I remember the different connections for Ethernet magjacks have to do with two things:1) Plastic of metal housings2) PoE is expected or notIf you want more info than you ever need about Ethernet, Würth has a book about it, \"Triology of magnetics\" one of the three books deep dive into it."
},
{
"post_id": "",
"author": "sw_guy",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 08, 2024, 07:06:00 pm",
"content": "Thanks for the information. I am sure there are plenty of books, but I was hoping maybe someone knows the answer.sw guy"
},
{
"post_id": "",
"author": "Halcyon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 09, 2024, 10:26:57 pm",
"content": "Duplicate post.https://www.eevblog.com/forum/projects/i-dont-know-how-to-wire-rj45-connector-with-magnets/"
}
] |
2025-10-17T16:40:55.230274
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1hz-square-waveclock-generator/
|
1Hz Square Wave/Clock Generator - Page 1
|
[
{
"post_id": "",
"author": "varunkoganti",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 26, 2021, 03:14:15 am",
"content": "Hi Everybody,The project is simple, I am trying to build a digital clock, this requires a 1Hz timing.My idea for the 1 Hz timing is to use a 32.768KHz crystal and then count the crystal using a 15-bit counter(2^15 = 32768), this would give me 1 sec.I built up the circuit (Pierce oscillator),Capacitors = 18pF.Rfeedback = 1M ohm.The inverter is a 74HC04 by TI(Texas Instruments).I tried measuring the wave form using my arduino's digital read and this is what i keep getting.I need help, is this actually correct, I do not have an oscilloscope."
},
{
"post_id": "",
"author": "perieanuo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 26, 2021, 06:44:40 am",
"content": "for 1HZ someone don't need a 1GHz capable scope, almost all multimeters today have ac freq functionto answer your question, we need oscillator's schematics, maybe osc photos, interface schematics with ardu, ardu code. not easy to digg into something with no info at all"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 26, 2021, 08:41:25 am",
"content": "The 74HC04 isn't the best IC to use for a crystal oscillator. The 74HCU04 is more suitable. The 74HC04 has buffered outputs. Each inverter really has three logic inverters connected in series. When configured in the linear region, the extra gain and phase shift can cause it to oscillate at an unpredictable high frequency.Why not use the 74HC4060? It contains an unbuffered gate and a counter, to give a range of lower frequencies, which are easier to use.There are also ICs, which are specifically designed to make a crystal oscillator such as the :74LVC1404 and 74LVC1GX04.https://www.ti.com/lit/ds/symlink/sn74lvc1404.pdfhttps://assets.nexperia.com/documents/data-sheet/74LVC1GX04.pdf"
},
{
"post_id": "",
"author": "varunkoganti",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 27, 2021, 03:04:52 am",
"content": "So i have looked into the suggested ICs, unfortunately I couldn't find DIP version of 74lv1404 at my location, I have had a look into 74HC4060, which was available.I made up the schematics. I will order these parts and try it out as per below on a breadboard."
},
{
"post_id": "",
"author": "retiredfeline",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 27, 2021, 04:15:29 am",
"content": "For the CD4060 I've used 10M for the resistor and it works."
}
] |
2025-10-17T17:25:08.618672
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1k-sine-single-fluctuates-a-bit-where-1k-square-is-steady-as-a-rock/
|
1k sine single fluctuates a bit where 1k square is steady as a rock? - Page 1
|
[
{
"post_id": "",
"author": "LiftedTrace",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 05, 2025, 10:40:20 pm",
"content": "I just got a new rogol DHO804 oscilloscope and a rogol DG1022Z signal gen.The signal gen only came with a dual ended bnc cable and i dont have any cables yet.So to play around, i used my provided scope probes that came with the oscilloscope.Both set to x1, i connected them together and sent a 1k sine wave out of the signal gen and the oscilloscope shows it as a fluctuating 1k signal.Its sublte variation, maybe 1.005k to .995k, but the signal on screen jostles too a bit.When doing a square wave, its dead on 1k, with no movements up or down.Im curious, what would cause the 1k sine to not be rock steady.Is it my poor probes provided with the oscilloscope?Is the signal gen not capable of providing a steady signal?Thanks."
},
{
"post_id": "",
"author": "ataradov",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2025, 12:17:50 am",
"content": "Show screenshot of the scope setup and the waveform. It may be your triggering setup."
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2025, 08:46:38 pm",
"content": "Quote from: LiftedTrace on March 05, 2025, 10:40:20 pmIt's unclear what you mean by \"subtle variation\" and \"the signal on screen jostles a bit.\"It would be clearer if you could provide a screenshot from the oscilloscope.If you're referring to measured frequency variations, that's normal. Oscilloscopes typically use a short measurement period, which can introduce noticeable measurement errors.If the waveform appears distorted, it could be due to an excessive amplitude setting, causing the generator to struggle to produce a clean signal."
},
{
"post_id": "",
"author": "LiftedTrace",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 06, 2025, 10:15:11 pm",
"content": "Quote from: radiolistener on March 06, 2025, 08:46:38 pmYeah when you have the measurements on screen, the measured freq fluctuates a bit and the amplitude fluctuates a bit. Im sort of new to this so I am not sure what is normal and what is not.Attached are two screen shots.The fluctuations are quite small I admit, I was expecting something like 1khz being so low to just be a nice firm steady trace like the square wave is.I suppose for a square wave its triggering off a vertical edge as opposed to a continually moving sine wave edge. I can see this being much more challenging to trigger in the same spot each time.The signal generator has trigger outputs, would this be a reason something like those would be used?Thanks."
},
{
"post_id": "",
"author": "Geoff-AU",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 06, 2025, 10:20:12 pm",
"content": "noise.1kHz is a very slow transition through the trigger point and noise in the system will alter the timing.yes, that's why a logic-level trigger is often provided in sig gens etc.oscilloscope frequency et al measurements are \"ok\", far from perfect."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2025, 10:33:19 pm",
"content": "Timing and frequency measurements result from the same system used for triggering.When triggering at zero or thereabouts, a square wave transition passes through the trigger level very, very quickly, so a bit of voltage noise causes very, very little shift of the time at trigger.The speed of the square wave transition is ideally infinite, but real square waves and dsos have a finite rise time and sample rate.A sine wave, however, has an inherent slope (slew rate) going through zero and therefore a small voltage noise will result in more random “jitter” in the timing than for a square wave."
},
{
"post_id": "",
"author": "LiftedTrace",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "March 06, 2025, 10:44:25 pm",
"content": "Quote from: TimFox on March 06, 2025, 10:33:19 pmI could test this, but is this saying that the higher the freq the more stable it will be because its passing though much faster and closer to a square wave, and a much slower freq might show even more wildly fluctuating values because its much slower passing through the trigger point?"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 06, 2025, 10:56:11 pm",
"content": "Quote from: LiftedTrace on March 06, 2025, 10:44:25 pmIf you increase the frequency, the speed through the trigger point increases, but the period between triggers decreases. Apply that to your question."
}
] |
2025-10-17T16:22:10.724770
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1kv-0-1ma-regulated-power-supply-feedback-layout-question/
|
1kV 0.1mA regulated power supply feedback layout question - Page 1
|
[
{
"post_id": "",
"author": "epkoncept",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 23, 2023, 04:46:51 pm",
"content": "Currently I am experimenting with a ~ 1kV DC-DC inverter used to power photomultiplier tubes. Current is low, 0.1mA or so. My feedback is a 1G ohm with a 220k or so trimmer at the bottom to provide thefeedback voltage of about 0.6V to the regulator circuit. Since the impedance of the feedback network is so high, I think it is susceptible to noise ingress. I was wondering if there are hints as to how to do the physical layout ? e.g., should the divider network be located next to the regulator circuit and the HV and gnd leads brought back there ? I think that having the divider network next to the output and then having a shielded lead bring the feedback signal to the regulator would pick up more noise than the former ? My goal is to have the ripple in the 1~ 2mV range. I am stuck with ripple in the 10~20mVpp range with a larger 60Hz ripple that is being picked up. Filtering the feedback voltage kills the loop response.P"
},
{
"post_id": "",
"author": "epkoncept",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 23, 2023, 05:02:57 pm",
"content": "my scribbled schematic."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 23, 2023, 05:47:59 pm",
"content": "Ideally the FB divider should be closer to the regulator - but ideally this also has a short link from the HV to the divider.There shoould be a good shield around the circuit, so 60 Hz ripple should not come in very much.If possible the divider should not be all the way down to 0.6 V, but use a higher reference voltage. If needed a negative ref (e.g. -5 V) instead of GND in the divider. This make the divider output even higher impedance, but still not more sensitive to pickup of hum.If the divider is too high impedance, one could use parallel capactors. A capacitive divider does not cause power loss and does not add noise, at least for the AC part. DC drift is still set by the resistor part though.The supply to the boost regulator still should be well regulated, not to get ripple from there."
},
{
"post_id": "",
"author": "epkoncept",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "October 23, 2023, 06:47:05 pm",
"content": "Kleinsteinthanks for the commentsCan't do much about the reference voltage its fixed to 0.6V in the MT3608 boost converter.Interesting that you mentioned a capacitive divider. I haven't used those in +30 years. Last time I saw them in use were in CRT TV set designs.May be the next step is to mock up the design in a shield enclosure to see if my 60Hz ripple is due to the unshielded proto or due to my measurement set up.P"
}
] |
2025-10-17T16:46:28.065679
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1kv-ac/
|
1kV AC - Page 1
|
[
{
"post_id": "",
"author": "jwbrooks",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 19, 2013, 06:49:44 pm",
"content": "ObjectiveI need 1kV AC at 60Hz. There should \"theoretically\" be no current because there is no load. (I think)RequirementsI need to energize two electrodes to a voltage around 1000VAC (anywhere b/w 600 to 2000 would be fine). The oscillations need to be centered around ground.Previous workI worked on this a while back. First, I tried using a 10to100V (ish) transformer and wired 120V up to the primary. I figured that since I didn't have a load that it shouldn't matter. It didn't work. This was two years ago (so I've forgotten a lot of what I did), and I didn't know electronics very well at all (still learning).Finally, I ended up using a ~$100 120VAC to 800VAC power transformer. It worked, but it was expensive.I've also wondered about using microwave transformers, but I've read scary things about them and would prefer something easier if possible.The QuestionlIs there a cheap(er) way to produce this voltage?"
},
{
"post_id": "",
"author": "Rerouter",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 19, 2013, 07:42:44 pm",
"content": "cheapest soultion i can come up with is a $25 neon sign 10KV transformer fed from a 120:16 step down or similar (equally cheap) transformeras quite a few neon transformers come with a center tap"
},
{
"post_id": "",
"author": "jwbrooks",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 19, 2013, 07:54:41 pm",
"content": "I'm not trying to be picky, but I'd prefer to have a single transformer if possible. I guess I'm looking for cheap and simple. Maybe too much?Thanks for your suggestion."
},
{
"post_id": "",
"author": "ConKbot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 19, 2013, 09:29:48 pm",
"content": "Hammond mfg has factory stock ofhttp://www.digikey.com/product-detail/en/714/714HM-ND/4555461020V, CT, 170mA, 180VA. At $75 each, not cheap, not horrifically expensive.Now that I think of it, 1 kv, center tapped is actually quite a PITA voltage to get. Its a high enough voltage its not commonly used, low enough that all your usually high voltage stuff is greatly above it. All the stuff that would run in that range is generally high frequency. The only possibly cheaper solution I can think of is 2x 460/480v or 575v control transformers put in series, run backwards."
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 19, 2013, 11:06:55 pm",
"content": "Could always rewind an existing transformer.Would have to add some insulation between the layers though, 1kV is high enough to break down standard enameled wire"
},
{
"post_id": "",
"author": "notsob",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 19, 2013, 11:28:44 pm",
"content": "As a suggestion, go to a car wrecking yard and get a couple of 2nd hand ignition coils, much higher voltage, but you may be able to open them and remove a lot of the HV side to suit what you wantbe aware this uses pulsed 12VDC input so you would need to provide your own 60Hz input at 12V"
},
{
"post_id": "",
"author": "AlfBaz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 19, 2013, 11:44:56 pm",
"content": "I don't know what voltages coal mines use in the US but here in oz they're mostly all 1000V to keep the size of trailing cables down. Nearly any scrap electrical equipment from this industry should have 1000V to 110/120V control transformer. Since you're not pulling any current simply use the secondary (120) as the primaryEdit: on second thoughts I doubt the 1000v side will be centre tapped"
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 12:20:08 am",
"content": "An oil burner ignition transformer is probably the closest to what you need - may need to reduce voltage though as output is likely to be a few kV- maybe run it on 24-48VAC from another transformer.Microwave oven transformer cheapest, but dangerous due to lack of current limiting. However if your output current requirement is small, you could use resistive or inductive current-limiting on the primary to reduce the hazard. However i suspect a cheap MOT probably runs partially in saturation, so this may not work well."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 12:33:13 am",
"content": "What about a transformer designed for the h.t. supply of vacuum tube circuits? I had lots of salvaged transformers from old vacuum tube equipment with h.t. windings producing something like 600 V as I recall. Presumably you could get a modern transformer designed for the same purpose if you can't find any old ones? I'm not sure if they would be center tapped, but if not you could perhaps put two such transformers in series."
},
{
"post_id": "",
"author": "codeboy2k",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 01:55:10 am",
"content": "Quote from: jwbrooks on December 19, 2013, 06:49:44 pmI'll play the devil's advocate here, and ask you why you think there will be no current ?You said \"no load\", and \"no load\" implies \"no current\" .... I say NO WORK DONE. Now, why do you want a transformer that produces 1kV but does no work ?? Surely you want it to dosomething??"
},
{
"post_id": "",
"author": "Anks",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 02:19:04 am",
"content": "I wound a 950v transformer recently on my own lathe so it cant be hard if you take the former to a winders and ask them to do the winding. The hard bit is dismantling the old transformer.Also why have a transformer that dose nothing!"
},
{
"post_id": "",
"author": "Macbeth",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 05:30:08 am",
"content": "Quote from: Anks on December 20, 2013, 02:19:04 amI like this - also, that set-up is a faceplate and \"dog\"? - my mini lathe only has a 4 jaw chuck and dead centre. I take it you use the auto feed to wind the wire and keep an eye on it to reverse it at the right end points? I want to wind my own transformers now!"
},
{
"post_id": "",
"author": "300EVIL",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 07:08:08 am",
"content": "A \"Bug Zapper\" transformer will get you really close to what your looking for...."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 05:30:10 pm",
"content": "If you are going to wind a transformer you will need to have a layer of insulating kapton sheet covering each completed layer of winding, along with a gap at the ends so that it will not flash over. Typically you will wind for 50-100V per layer, so to get to the 1kv centre tapped one you want that will be between 20 to 40 layers of windings with kapton tape cover. Needs a big core, and as the primary will be wound below it the leadouts will need to be insulated for 2kV fro them as well, along with at least 5 layers of Kapton tape as winding separator between primary and secondary. If you really need equal capacitance windings then you will need to split the windings so each half is wound at the same time on just under half the core width, with a spacer tape applied to each layer to keep the tape layer flat. Those are a PITA to wind, I have done some for other voltages that are lower, and they take a day or more to get done properly, as you are going slow and with 2 spools with a lot of stopping for tape and tie down.."
},
{
"post_id": "",
"author": "Anks",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 06:52:27 pm",
"content": "Quote from: Macbeth on December 20, 2013, 05:30:08 amIt would be easier with a chuck Id imagine. the feed was done with a old hacked printer and micro to control the stepper.here is a pic of the setupI second SeanB about making sure you use insulation but I used thin wire as I only needed a small amount of current."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 07:29:47 pm",
"content": "I took apart an electric fence energiser that had this construction where the failure was that the outer layer arced over ( was a bloody pain literally to unpot the transformer from the GRP resin they filled the housing with) at the point where the sleeving they used was next to another wire. That killed the unit, it still made voltage but it was not the 10kV needed for the fence, more like 1kV or less with the internal arcing. Drive was a 30uf capacitor charged to 300v discharged by a really beefy TRIAC, with the thin wire providing current limiting along with the ESR of the poor film capacitor."
},
{
"post_id": "",
"author": "jwbrooks",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 20, 2013, 08:15:58 pm",
"content": "I like these ideas. I'm going to have to look into the bug zapper transformer. Unfortunately, it doesn't seem to be a very common thing to sell on ebay.To answer the other questions, there is no official load because I'm using these as electrodes. I'm planning on making a Paul trap (a type of ion trap), and trapping small charged particles (like corn starch)."
},
{
"post_id": "",
"author": "300EVIL",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "December 20, 2013, 10:34:35 pm",
"content": "Quote from: jwbrooks on December 20, 2013, 08:15:58 pmI'd look on craigslist for a used one. I find them next to garbage cans all the time. Almost a regular staple at garage sales."
},
{
"post_id": "",
"author": "TheBay",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 21, 2013, 02:27:12 am",
"content": "Find a cheap fluorescent camping light"
}
] |
2025-10-17T20:11:30.043453
| 19
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1ma-to-100a-bidirectional-current-measurement-in-solar-systems/
|
1mA to 100A bidirectional current measurement in solar systems? - Page 1
|
[
{
"post_id": "",
"author": "e100",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 15, 2025, 01:39:22 am",
"content": "None of the commercial coulomb counters used to calculate the state of charge (SOC) of LiFePO4 batteries have the range needed to cope with rapidly changing very high and very low input and output currents. Therefore over time the battery real SOC becomes less than the calculated SOC. As far as I'm aware the only fix is to periodically fully charge or fully discharge the battery to 'reset' the system end points, however fully charging or fully discharging a working system may not be possible.Is this an unsolvable problem, or is it that the cost is too high to be commercially viable?"
},
{
"post_id": "",
"author": "indeterminate",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "March 15, 2025, 06:34:41 am",
"content": "It is not a problem that needs solving.just bring the battery up to 100% charge and balance the cells while you are there and call it 100% soc.There are times in winter where we can go weeks without hitting 100 percent charge , if the soc is out a couple of present who cares.The cost of making things more accurate is just to high."
},
{
"post_id": "",
"author": "Smokey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2025, 06:36:09 am",
"content": "Not an expert, but that sounds like a dual range sensing problem to me. Use two systems, both of which are always measuring the current. One optimized for small currents and another optimized for large currents. Then have a system that monitors both and uses the appropriate data at the appropriate times."
},
{
"post_id": "",
"author": "voltsandjolts",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 15, 2025, 08:50:39 am",
"content": "For high current sensing, these are about the best dynamic range you can get in one sensor;https://www.lem.com/en/fluxgate-current-sensorsBut they wouldn't meet your 1mA to 100A requirement. So, yeh, multi-sensor design.Or just consider whether it's really needed."
},
{
"post_id": "",
"author": "e100",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 15, 2025, 09:26:49 am",
"content": "Quote from: Smokey on March 15, 2025, 06:36:09 amThat something new to me. I found a bunch of automotive dual range sensors but the low range seems to stop at about 50 amps."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2025, 09:53:36 am",
"content": "For really getting 2 ranges one needs to switch the shunt. This works OK for small currents like 1 or 10 A as upper limit, but not really well for the high currents. 1 mA to 100 A is a large dynamic range, like found in a 6 digit DMM - so not a cheap thing.Coulomb counting can be done with better accuracy, but one still has the problem of an offset and integrating over long times (like 1 year).The charge balancing can also not include battery internal leakage currents.For the Li-batteries one can still use the voltage and temperature to get a reasonable good value for the charge state. This may not work well all the time (e.g. just after fast charging or high loads), but for these phases the coulomb counting should work well. After a long time this will be more accurate than charge balancing. One could use both methods in parallel to check the voltage / charge curve and average over reading during charging and discharging."
},
{
"post_id": "",
"author": "Smokey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 15, 2025, 08:07:59 pm",
"content": "Quote from: e100 on March 15, 2025, 09:26:49 amsorry, should have been more specific. I'm talking about two separate sensors, and then some processor to to read them and decide which to use based on rangeing.If you use hall sensors, like the ones with the hole, you can do multiple turns to increase the sensitivity. One turn for high range, multiple turns for low range. I'm not saying this one specifically, but like this:https://www.digikey.com/en/products/detail/tamura/L34S200D15T/11696449"
},
{
"post_id": "",
"author": "Rick Law",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 17, 2025, 08:07:53 pm",
"content": "Quote from: e100 on March 15, 2025, 01:39:22 amQuestion often is, how much is it worth? and is it even useful?From 100A to 1ma, that is, 100,000mA to 1mA = 0.001%. This is the same range of measuring the weight of a Tesla Cyber Truck accurate to the ounce. (per Wikipedia, it weights 6603 to 6843lbs, 1 ounce is 0.000947% of 6603lbs.) Have the weight to the ounce could allow you to calculate Kw/Watt in this 0.001% precision range -- but a bag of potato chip in the car will change your result.Similarly, environmental condition (temperature) and self-discharge of your batteries will affect the SOC by likely > 1%There is no point in measuring one part with extreme precision while other parts have much higher natural variations."
},
{
"post_id": "",
"author": "mtwieg",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 18, 2025, 11:56:57 am",
"content": "I'm also having trouble thinking of a scenario in which such a huge dynamic range of current sensing would meaningfully affect your SoC/SoH estimation. Self-discharge is likely more significant than such small currents."
}
] |
2025-10-17T16:21:35.833371
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1mhz-circuit-diodes-which-ones/
|
1MHz circuit diodes, which ones? - Page 1
|
[
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2016, 10:33:55 pm",
"content": "Hi all,I am building two circuits, something quite simple, two diode bridges rectifiers, something like this:https://upload.wikimedia.org/wikipedia/commons/thumb/f/f5/Diode_bridge_alt_2.svg/2000px-Diode_bridge_alt_2.svg.pngThe input frequenceis for the two circuits are 700kHz and 1MHz for the other one. What kind of diodes do I need? And which parameter do I have to look at?I have some SM540 MIC but I don't know in which frequency ranges they work, or up to which frequencyI am working with small power and voltage values (mW, 1V)Thank you"
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2016, 10:47:38 pm",
"content": "Basically look at Trr, reverse recovery time, and capacitance.High speed circuits, much faster than yours, typically will use smallsignal Shottky or Galium Arsenide doped diodes.Regards, Dana."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2016, 11:20:21 pm",
"content": "You didn't say anything about the load current and that's an important consideration. For small signal levels, I don't see why a common 1N914 can't be used. The Reverse Recovery Time is just 4 nS. The 1N4148 can probably do the job as well."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2016, 11:26:17 pm",
"content": "Quote from: rstofer on May 06, 2016, 11:20:21 pmhonestly I just don't know what to use. I have these RS540 diodes but apparently I am not able to retify the signal at higher frequencies"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2016, 12:05:49 am",
"content": "Quote from: raff5184 on May 06, 2016, 11:26:17 pmI can't find a diode datasheet for the part numbers you've cited (SM540MIC and RS540). Are you sure you've got the part number right?Please show the actual schematics you are working with. Yes, the picture you linked above is a FWB, we've got that. It's not enough information to be able to answer your question though.I agree with the above posters. For small load currents 1n914/1n4148 should work. For larger loads the right-rated Schottky diodes would probably work."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 07, 2016, 12:20:21 am",
"content": "sorry my bad, I ment:SR 540 MIChttp://www.alldatasheet.com/datasheet-pdf/pdf/191379/WTE/SR540.htmlI'll post the schematic asap"
},
{
"post_id": "",
"author": "amspire",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2016, 12:20:34 am",
"content": "1N4148 (1N914) diodes are the kind of diode you should have - you can get a bag of 100 for hardly any money on eBay or Aliexpress.But at 1V, you are better with Schottky diodes as they have a lower drop and have less stored charge every time they switch. 1N4148 switch on about 0.6-0.7V and so they are not great in a 1V bridge.If you have any scrap motherboards, you can often salvage 3 pin surface mount chips commonly of the BAT54 family of Schottky diodes. These are 30V diodes and at 10mA, they have a 0.3V forward voltage drop. At 1mA, the drop is about 0.13V. You can of course buy them, but I like free. There are versions with different single/dual diode arrangements and all can be used in a bridged rectifier.http://www.nxp.com/documents/data_sheet/BAT54_SER.pdfYou can identify them from other 3 pin devices by their low voltage drop. If you have a multimeter on the Diode range, transistor junctions will give a 0.6-0.7V drop, Schottky diodes will give a 0.1-0.3V drop. Mosfets like the 2N7002 (also common on motherboards) will not seem to have a junction at all."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2016, 06:29:20 am",
"content": "Impossible to recommend without:- Voltage- Current- Circuit impedance- other stats (switching or RF? Power range?)We could go to great lengths to explain all the many properties that vary between types of diodes, but that probably wouldn't be very useful, and would end up saturating you with otherwise-useless information.Tim"
},
{
"post_id": "",
"author": "rch",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 07, 2016, 01:47:17 pm",
"content": "Just to add to the questions to the OP, what is the purpose of the rectifier? Power transfer, accurate voltage measurement, demodulation? And what is the impedance of the following circuit? It's hard to prioritise characteristics if we don't know what it is for."
},
{
"post_id": "",
"author": "bson",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 07, 2016, 10:24:00 pm",
"content": "Quote from: raff5184 on May 06, 2016, 11:26:17 pmDiodes cost pennies. Just buy a strip of 25 or 50 of each of a few different ones and try them out. 1MHz is utterly mundane and doesn't require anything special; it's not \"higher frequencies\". 1N4148 will work just fine at 10x or even 25x this. You can even evaluate a 1MHz small-signal circuit on a breadboard, no problem at all.By the way, even 1N400x style rectifier diodes (x = current rating in amp, so 1N4005 is a 5A rectifier diode) are rated for junction capacitance and recovery at 1MHz."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2016, 11:06:32 pm",
"content": "Capacitance depends on diffusion of charge carriers, so has a lossy diffusion characteristic at quite high frequencies (100s MHz?), regardless of doping. (Purpose made varactors are low voltage devices, so have stronger doping and thinner junctions, and are good to much higher frequencies. They're probably also constructed differently, having lower series resistance.) At modest frequencies, and low enough amplitudes, it truly does look like a pure capacitance.Typical recovery for a 1N400x series is several microseconds, so one wouldn't be able to be tested with a pulse repetition rate much over 200kHz.Tim"
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 08, 2016, 02:18:11 am",
"content": "thank you for all your replies.So basically this is the circuit, very simple:http://www.radio-electronics.com/info/circuits/diode-rectifier/diode-rectifier-full-wave-bridge-01.gif- the source is a 700kHz or 1Mhz continous wave, with less than 2V peak-to-peak (can be between 300mV and 2V) coming from a waveform generator or some ultrasonic transducer.- the load is 1 MOhmThese are the characteristics of my diodes:http://www.alldatasheet.com/datasheet-pdf/pdf/191379/WTE/SR540.htmlThe question is, should it work? I am asking to understand if I'm doing something wrong or if it depends on the diodes.I'll try with other types like 1N4148 (1N914)..."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 08, 2016, 02:22:50 am",
"content": "Quote from: rch on May 07, 2016, 01:47:17 pmIt is for power transfer, I don't need accuracy"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2016, 05:23:34 am",
"content": "Then a smaller diode like 1N4148 or BAT85 should be fine.Tim"
},
{
"post_id": "",
"author": "bson",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 08, 2016, 06:18:34 am",
"content": "Quote from: blueskull on May 07, 2016, 10:59:24 pmYou're absolutely right, what was I thinking... Anyway, I'm sure they'd still be fine at smaller voltages, like 9VAC at 1MHz, maybe even 1A. (Or, hmm, tesla seems to think recovery is too slow... clearly 1MHz power rectification is a really odd application, even low voltage.) For small signal use they're a bit capacitive though.Edit: I just tested a 1N4004 and it absolutely SUCKS for small-signal use. Meh. It's not usable past a few kHz, at 5kHz it leaks a ton of AC through due to overshoot. The 1N4148 is perfectly fine at 1MHz."
},
{
"post_id": "",
"author": "amspire",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2016, 06:28:00 am",
"content": "Quote from: raff5184 on May 08, 2016, 02:18:11 amThe SR540 have too much capacitance. The 1N4148 will be OK, but they will not handle the low voltages well. Remember, there are two diode drops in the diode bridge, and even with a 1M load, there is still about 0.5V across each 1N4148. Ideally, you want to look for Schottky signal diodes with as low a capacitance as possible."
},
{
"post_id": "",
"author": "bson",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 08, 2016, 06:55:55 am",
"content": "For 2V, Shottkys might be a good choice though due to the lower forward voltages."
},
{
"post_id": "",
"author": "rch",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 08, 2016, 09:03:48 am",
"content": "Did you really mean that the load is 1 megohm? This circuit is not going to work at 1 MHz with such a large value load, as even the capacitance of a small signal diode is going to be a fraction of this impedance, so the diodes will look more like capacitors then diodes, and conduct more or less equally in both directions. If you want power, you are only going to get a microWatt at this load. If you put a capacitor in parallel with the load resistance (lowering the load impedance at 1MHz) you will probably get the peak to peak DC voltage across the load. If you want to see the full wave rectified output on an oscilloscope as in your circuit diagram, try a load of 1kOhm and signal diodes."
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2016, 02:01:48 pm",
"content": "Just for fun....Scoping a commercial FWB (D3SBA60, nominal rating 600V 4A) using a low voltage input and differential output measurement (A-B) at about 60 Hz and about 600 kHz.Comments?"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2016, 02:35:31 pm",
"content": "Same as above but with 1n4148 diodes and 1 megohm load."
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2016, 02:39:22 pm",
"content": "Now with 1n4148 diodes and 1000 ohm load, with reduced input voltage.(Note horizontal Math error at 500 ns/div.)"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2016, 05:29:12 pm",
"content": "For such a small signal a full wave rectifier bridge is likely not the right circuit, as there is quite some signal lost below 0.5-1.5 V depending on the diodes.For higher frequencies and not to much performance need one might use the 1N4007 as a low cost PIN diode - so not as a normal diode but as a DC current controlled HF switch / attenuator.To see how slow a 1N400x is, just put a +-2 V rectangular signal from a 50 Ohms source to the diode and watch the voltage - this is an easy way to measure and show reverse recovery."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2016, 12:50:02 am",
"content": "hi again,so I got some 1N4148 diodes, applied a 2V pp voltage at 700 kHz in input to the rectifier. Load is 1 kOhmThe result is pretty bad.If I reduce the input voltage the \"rectified signal\" it is similar, just smaller"
},
{
"post_id": "",
"author": "amspire",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 01:36:09 am",
"content": "Quote from: raff5184 on June 01, 2016, 12:50:02 amThe shape is exactly as expected. The reason I suggested Schottky diodes is with the much lower turn on voltage, you will get a much better rectified waveform. The 1N4148s are only turning on at the peaks of the input signal. I don't understand why it isn't a clean waveform - it looks like you are using an AM modulated 700KHz."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2016, 01:50:24 am",
"content": "I don't know either. The input signal is a very clean sinusoid.So if I understood correctly there isn't much I can do to see a rectified signal with 1N4148s (uless I work with much higher voltages)?Schottky BAT54 are only with 3pins? Is there any equivalent with 2 pins?"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 03:01:08 am",
"content": "The AC input and DC output cannot BOTH be common to the same ground reference.You need isolation.Tim"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 04:49:50 am",
"content": "It's deja vu all over again...."
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 05:15:55 am",
"content": "Quote from: raff5184 on June 01, 2016, 01:50:24 amIt is likely that your Function Generator's output BNC shield is grounded to the FG's chassis which in turn is grounded to the mains, and so back through the mains to your scope probe's ground reference lead. So when you connect one scope probe to the output of the bridge in the \"usual\" manner (probe tip to bridge + and probe ground clip to bridge -) you are in fact creating a groundloop between the AC input from the FG to the output of the bridge. So you are seeing a distorted signal and only one-half of the bridge output. To get around this problem you either need to use an expensive isolated differential voltage probe on the bridge output, OR make a differential measurement of the output using two scope channels, no probe ground connections, and math to subtract, as I showed in the scopetraces I posted on the previous page.If you want your bridge to work well at 2V input then Schottky diodes are probably necessary. 1n5817 for example.If you are set on using surface mount BAT54 series diodes you can use one BAT54A and one BAT54C, or two BAT54S, to construct your FWB. These contain two diodes each, in common-anode (A) and common-cathode (C) and series (S) connections. The plain BAT54 (no letter suffix) has three leads also but only contains one diode and the third lead is not connected internally. But they are in tiny SOT-23 packages!"
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2016, 06:23:18 am",
"content": "thanks alsetalokin4017 I'll try with a differential measurement as you showed in other posts.I saw the schematics of the different BAT54's, now it makes more sense why there are two diodes.I'll first try with 4 BAT54 (I already ordered them) and than with the other solutions you suggested.Since the third pin is not connected, can I ignore it?Sorry guys if these questions are basic but I have no practical experience and don't know where to find this information, which diodes are used, what they are called and so on. I know the theory but apparently it doesn't help. But thanks to you I'm getting a grasp on these topics"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 04:35:07 pm",
"content": "No offence intended, but with \"no practical experience\" I'm wondering how you are going to be working with SOT-23 package devices..... but yes, you can ignore the non-connected pin on the BAT54. Usually it will be soldered to a pad for mounting purposes but not connected electrically to anything."
},
{
"post_id": "",
"author": "raff5184",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2016, 05:15:55 pm",
"content": "no problem alsetalokin, no offense.I'll learn step by step, read guides that I can find on the Internet, trial and error... I have to start somewhere.Btw if you know any good PRACTICAL guidebook feel free to suggest it.Thanks"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 06:04:51 pm",
"content": "If you are set on using the BAT54 diodes you may want to look at getting some adapters or breakout boards that will allow you to mount your SOT23 devices and use them like standard DIP or SIP packages on your breadboard. There are many manufacturers and vendors of these things. You can solder the SOT23 pins with a fine-tipped iron and very thin solder. It may take some practice..."
}
] |
2025-10-17T19:17:34.267988
| 32
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1mhz-diode-laser-power-supply/
|
1MHz diode laser power supply - Page 1
|
[
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 07, 2025, 08:30:27 am",
"content": "Hi,I am looking into building this modulable laser diode power supply (schematic attached also)https://www.repairfaq.org/sam/laserdps.htm#dpsldd317but of course some of the parts are not available for me.Looking at a few datasheets, would AD8022 be a good replacement for the LT1215 ?https://www.analog.com/en/products/lt1215.htmlhttps://www.analog.com/en/products/ad8022.htmlI also want to replace the potentiometer with a digital pot, as in my application I'd like to control it with a microcontroller. But the digital pot i can find is not 1K but 5k.I see it is basically used as a voltage divider to determine a setpoint for minimum current in the diode but I am not sure how a different value would affect the circuit overall.How important is it in this circuit for the pot to be 1k ? what would be the effect if I used 5K instead of 1k ?Cheers and thanks for all help"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 07, 2025, 10:37:58 am",
"content": "The LM317 datasheet doesn't have sensible figures for operation at anything other than DC, but looking at the typical transient response and output impedance curves, I would be surprised if it produces a clean waveform at 1MHz. I could be wrong of course - I don't run components outside their datasheet specifications."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 07, 2025, 11:17:00 am",
"content": "Quote from: bschwand on February 07, 2025, 08:30:27 amWhy not just use the LT1215 specified? It’s readily available, so just order one. The AD8022 would probably work, but its much higher bandwidth could make it more prone to oscillation.The issue with the 5k digipot might be the impedance of the subsequent op-amp stage. With the 1k pot, the highest impedance is 1k, which is low compared to the following stage’s 3.3k input impedance. 5k, on the other hand, is higher, so you might have problems.Again, 1k digipots are readily available, so just buy one."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 07, 2025, 01:50:32 pm",
"content": "Quote from: tooki on February 07, 2025, 11:17:00 amhmm well I said I can't get the parts listed and ask how those I might be able to get would suit, and you tell me to just buy the parts listed...Thanks for explaining the issue with the 5k pot.For the bandwidth, can you explain how this works or point me in the right direction ? I searched for opamps with 50V/us slew rate and the AD8022 has the appropriate slew rate but has a 120MHz bandwidth. However the LT1215 lists the gain bandwidth _product_ as 23MHz so I'd say it is not directly comparable.If I look at the large signal bandwidth, the 8022 has 4MHz for 4Vp-p and the LT1215 2MHz 2.5Vp-pWhat about an opAmp with same slew rate but lower bandwidth ? would that be more stable ?"
},
{
"post_id": "",
"author": "benj38",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 07, 2025, 04:12:45 pm",
"content": "Quote from: bschwand on February 07, 2025, 01:50:32 pmI couldn't help noticing that according to your profiles both you and @tooki are from Switzerland (in fact, less than 100 Miles from each other). I guess, that if @tooki can easily get these parts so can you. Maybe you should ask him for a recommendation of where to buy them."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 07, 2025, 04:17:59 pm",
"content": "Quote from: benj38 on February 07, 2025, 04:12:45 pmgeography is not the sole criteria here.Is this a place to learn or just buy stuff from lists ?"
},
{
"post_id": "",
"author": "benj38",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 07, 2025, 05:26:00 pm",
"content": "Quote from: bschwand on February 07, 2025, 04:17:59 pmI fully understand you. However, note that this is not a place to only learn, it is a place toget help. Hence, members sometimes suggest solutions that are not simply answers to questions asked. It is all done in a genuine attempt to help.If you just want answers to theoretical questions about circuit design then please make it clear. It was not made clear in your original post, so we also responded to your comment that you can not get these parts, trying to help you get them. I am sure that you can imagine a scenario where a person would be happy to find out that there are other ways to get parts that he did not know about.Now that it is clear that all you want is to learn about the circuit and the effects of your suggested changes, and not anything else, perhaps some other members will try to help you with that."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 07, 2025, 11:42:50 pm",
"content": "Quote from: bschwand on February 07, 2025, 01:50:32 pmWell you said they are “not available to you”. But theyareavailable to you: we live in the same country, so if they’re available to me, they’re also available to you. “I can’t/won’t buy them” is not the same thing.Anyhow, your best chances of success are using the parts specified in the design. The more you start replacing, the more risk it might not work.Quote from: bschwand on February 07, 2025, 01:50:32 pmI’m not an expert on this, but it’s just a rule of thumb that higher bandwidth amps are more susceptible to oscillation. But it also depends on the internal design of the amp (not just the schematic of its insides, but the physical implementation). Again, I’m not saying it definitely won’t work, just that there is a bit more risk with it. (But nowhere near the risk of, say, an amp with multi-GHz bandwidth.)"
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 09, 2025, 09:43:55 pm",
"content": "I really do not want to be curt or rude but, seriously ?Quote from: tooki on February 07, 2025, 11:42:50 pm<rant>tooki, do you know where I am currently ? Do you know what constraints I am living under ? do you have any idea if I am actually living right now in the same region or location ? am I travelling in africa or somewhere else ? do you know my financial means or ability to order or pay or anything else ? Do you know anything about how or why I could or could not procure certain components ?NO, you don't. I was very clear,\"some of the parts are not available for me\"I thought that set the stage pretty clearly and unequivocally as \"I am looking for alternatives\"The bottom line is this: I ask if some components would be a good fit as alternative for certain ones that ARE NOT AVAILABLE TO ME. If they were available TO ME, I would get them.This seems to be a common practice, to find and select alternative components.So why is everyone telling me to just buy them and insisting that yes in fact those components are available to me even when I say they are not ? No, they are not and there are zillions of possible reasons for that which you can't possibly know.</rant>with that hopefully clearly settled, thank you very much for the comments on the component selection and the effects, I guess I have more studying to do. If there is any other advice on component selection I will gladly accept it."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 09, 2025, 09:48:51 pm",
"content": "Quote from: Gyro on February 07, 2025, 10:37:58 amThanks, I understand that this circuit is kind of a hack taking advantage of the LM317 characteristics, so probably not something to use for a product but instead a good cheap way to achieve the goals for a hobbyist. That is fine with me. I would actually be interested to measure how bad or good this circuit is compared to some supposedly well designed existing products."
},
{
"post_id": "",
"author": "mtwieg",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 10, 2025, 08:40:45 pm",
"content": "To answer the original question, no I don't think the AD8022 is a viable replacement, mainly for these reasons:1. The input common mode range does not extend down to GND. The first stage opamp is going to have its inputs biased around 0.85V (not sure about the second stage). The input common mode voltage range of the AD8022 is limited to ~0.75V above -Vs, which leaves very little margin to work with.2. The output range doesn't extend down to GND. The datasheet says it can only get within 1.4V of -Vs (that's while sinking current, doesn't say what to expect with a high impedance load). In the worst case the second stage would saturate with its Vout at 1.4V, meaning the LM317 output would never go below 2.65V. If the Vf of your LED isn't higher than that, then the LED will never turn off.That aside, I don't think the circuit shown in the schematic would work even with the LT1215. As shown, the LM317 and U1/B are connected to create positive feedback... and even if that's fixed then the circuit will end up regulating load voltage instead of load current (not good when the load is a diode....)."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 11, 2025, 12:19:19 am",
"content": "Quote from: mtwieg on February 10, 2025, 08:40:45 pmThanks, makes perfect sense about the 8022.Why would the circuit regulate load voltage and not load current ? The output resistor R11 would be fixing the current, wouldn't it ?"
},
{
"post_id": "",
"author": "mtwieg",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 11, 2025, 03:06:13 pm",
"content": "Quote from: bschwand on February 11, 2025, 12:19:19 amNo, R11 doesn't really do anything in this schematic (as drawn, anyways).Actually it does regulate output current, just in an unconventional way (not by measuring output current and comparing it to a reference with an error amplifier). The feeback is positive, but not strong enough to make the circuit unstable (at low frequencies, anyways). More like feedforward than feedback, I guess.Ultimately, it should output anode current Ianode = (1.25V - Vpot)/R11, where Vpot is the voltage from the tap of VR1. The written description on the website doesn't actually do any quantitative analysis, just has lots of confusing prose. Seems to be talking about a completely different circuit sometimes. For example:QuoteThere's no zener diode or 100R resistor involved with the second opamp stage. There is no C3 or C4 on the schematic at all. No idea what is meant by the \"input socket\"..."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 11, 2025, 05:08:41 pm",
"content": "Quote from: mtwieg on February 11, 2025, 03:06:13 pmThe C3 and C4 are on the PCB artwork actually, but not the schematic. I guess because they are decoupling capacitors for the OpAmpThe 100 ohm input resistor is R9 and the input Zener diode is D1, they are both on the schematic, and I agree it is a bit convoluted but at that point of the description he is talking about filtering the input modulation so I think it makes sense tht R9/D1 (and D1's capacitance) effectively would be an RC filter on the input.Quoteyes, I think that is what he describes asQuoteIt is rather unconventional, which makes it interesting to understand"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 11, 2025, 06:47:05 pm",
"content": "Quote from: bschwand on February 09, 2025, 09:43:55 pmThis is just an FYI: perhaps it's a language barrier issue, but at least in English (my native language), \"not available to me\" isnotthe same thing as \"I am unable to buy because of \".Availabilityis whether the market makes the thing available for purchase, it says nothing about your ability to purchase. 1kg bars of gold are available for purchase at my bank; that says nothing about my inability to afford one!So given that it's not uncommon on the forums for people to say \"X isn't available\" when in fact it is, but they just didn't know where/how to get it, and your choice of wording (which \"places the blame\" on the sellers, not the buyer), it's absolutely reasonable for people to try and guide you towards sources for the supposedly-unavailable part. It really is not rare for people to ask for alternatives for something because they simply failed to find a source for the original, and they're often quite happy to find out that the original is actually available.So don't get your knickers in such a twist. Accept that your choice of wording doesn't actually mean what you think it does, and that you can tell people \"oh, sorry, I actually just meant that there are other factors preventing me from ordering from mainstream distributors\" graciously."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 11, 2025, 08:09:27 pm",
"content": "Quote\"not available for me\"the operative part of this sentence isFOR MEI never said the part is not available. You conflated that.I wrote\"not available for me\"Who is getting his knickers in a twist here ?maybe stop trying to backtrack and justify your own misunderstanding and assumptions and maybe question your own mastery of the english language since it is your native language; instead of sneakily implying that I clearly do not understand and can't write english, unlike you who are clearly a native english speaker and therefore can correct what I wrote so incorrectly to purvey the exact meaning of my thoughts, thank you so much.The reason for my rant is because you (and other) repeatedly insisted that I just buy the parts even though I repeatedly said I am not getting those parts and asked for technical advice, but you keep insisting and making up stuff about my situation that you know absolutely nothing about.QuoteThat is exactly what I did. But it was not enough, you have to keep bringing it up, yet again.PS: and if you really were just so helpfully showing a poor soul unable to order parts online, why didn't you actually give a useful answer: maybe a link to suppliers and price for the part, instead of repeating ad nauseam that the part is indeed available and just do it ? what is the point of that kind of \"help\" ? there is nothing, no actionable information.I am not interested in that kind of debate, thank you"
},
{
"post_id": "",
"author": "LaserSteve",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 11, 2025, 08:21:47 pm",
"content": "Knowing a bit more about the particular designer of that circuit then most, take it cautiously. Test it on a simulated LD first.This was the same gentleman who advocated testing collimated and raw RED LDs by exposing them to 100% back reflections from a mirror before mounting them in arrays. (For most LDs this is often lethal, blows the output end mirror off from intracavity energy density issues.)That circuit is a work in progress at best. I built it many, many, years ago and it had stability problems to say the least.Sam was sent a test board after I flagged the design for issues. It seems some brands of LM317 are more suited than others.Steve"
},
{
"post_id": "",
"author": "mtwieg",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 11, 2025, 10:03:32 pm",
"content": "Yeah the suitability of the LM317 for controlling fast pulses is dubious at best, would not be surprised at all if different versions from different manufacturers behaved very differently. Also there's the issue that the LM317 has a minimum load current of 10mA in order to regulate properly. So your LED current would likely never go below 10mA.Also don't blind anyone, practice your safety squint, etc"
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 11, 2025, 10:12:57 pm",
"content": "Quote from: mtwieg on February 11, 2025, 10:03:32 pmI was hoping to use that (or some variation) with a higher power LD (in the 3.5A range) with an LM338 instead of the LM317Obviously just experiments and play for nowYeah, I know, don't look in the laser with remaining eye...seriously, I will set up stuff so I am not even in the same room when it fires, and observe with a webcam from behind a nice concrete wall"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 12, 2025, 12:21:11 am",
"content": "Quote from: bschwand on February 11, 2025, 08:09:27 pmI didn’t misunderstand or make up anything: you simply didn’t write what you actually meant. (The key being that “not available” — including in “not available to me” — puts the root causeawayfrom you. It means the supplying party is preventing you from getting it.)Quote from: bschwand on February 11, 2025, 08:09:27 pmMy apologies. I thought it was quite clear that I was saying that.Jokes aside, your English is quite good overall. But you are definitely lacking some understanding of nuance and connotation, at least of the phrase in question.Quote from: bschwand on February 11, 2025, 08:09:27 pm…because your wording suggested that you had failed to find a supplier capable of selling them to you, not thatyouare unwilling/incapable of buying from those suppliers who could sell them to you. So being reminded that the parts can in fact be sold to you could be useful information to someone who had simply not known where to buy them. Or perhaps a nudge to try a bit harder to find the parts.But moreover, as I tried explaining to you in the last reply (and others explained to you as well), it is not uncommon for people to respond with an answer that isn’t quite what’s been asked, because what people think they need is not always what they actually need. We see this a lot, and it’s not an insult or attempt at disrespect or anything. It’s an attempt to get you from point A to B the best way. The more detail you provide, the better.Quote from: bschwand on February 11, 2025, 08:09:27 pmNobody made up anything. We can only go by what information you shared, like your country flag. You are, in actuality, getting annoyed at us fornotbeing clairvoyant.Quote from: bschwand on February 11, 2025, 08:09:27 pmWell no, you quite immediately started getting annoyed and snarky. I’ve only tried to explainwhyyou got the response you did. And I did, at the same time, also try to answer your questions about the substitutes to the best of my ability.Quote from: bschwand on February 11, 2025, 08:09:27 pmYou can ask for that. But it’s also not our job to do your homework for you. Being informed that the parts are, in fact, available for purchaseisactionable information, because it means that it is not a waste of time for you to try and find it. It’s important to learn how to find things on your own. When someone has demonstrated that they made an effort (e.g. by stating what they did and where they ran into trouble) people are happy to help out.Note also that I actually said “readily available”, meaning that finding them is not difficult at all. It’s not like I found them on some obscure dealer of rare parts, I found them at the mainstream distributors.(Also, twice is not “ad nauseam”.)But here’s a useful free tip: search for parts on octopart.com. It searches all the major distributors (and some smaller ones). (Reichelt is the only one that is missing that I wish were there.) Search there, change the currency as needed. Saves TONS of time compared to searching each distributor individually.The other tip I’ll give for Switzerland is that the following distributors all ship with customs pre-cleared, meaning no nasty surprise bills from the post/UPS/FedEx/DHL: DigiKey, Mouser, Farnell, Reichelt, Conrad, Distrelec, RS*. The first two have free shipping on orders above ~CHF 54, Farnell for orders above 75 euros. The first three also ship very quickly and have very reliable delivery dates.*Doesn’t sell to consumers, so you must order through a company."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 12, 2025, 03:23:54 pm",
"content": "Quote from: tooki on February 12, 2025, 12:21:11 amok, thanks, I am glad EEVBlog has such highly skilled erudite linguistsalthough look what an interesting number one definition Merriam-Webster gives me:available/ə-vā′lə-bəl/adjectivePresent and ready for use; at hand; accessible.\"kept a fire extinguisher available at all times.\"components not present, not ready, not at hand, not accessible. I guess I am using the word correctly and even eliminated some degree of confusion by precising \"FOR ME\"The root cause is away from me, wether the supplier is able or preventing me from getting it or not, since other factors independent from both me and the supplier are at work. I certainly would agree that in the vernacular language, \"availability\" is mainly predicated on the supplier's capacity to provide the items, and less on extraneous forces, which is why I qualified it with \"for me\" in an obviously vain attempt to reduce misunderstanding.Yes, other posts not from you in this thread (and even from other places) added insult to injury by also insisting multiple times that I just buy the stuff; it certainly rubbed the wrong way and lead to my rant. When you are trying to make do and learn, and all you hear from everyone everywhere in this consumerist-no-ownership-everything-is-disposable-service-subscription-based world we live in, is to just buy the stuff... it gets really old.Well, I'd love to continue discussing linguistics nuances but obviously it's not the point of this forum.Thanks for the tips on suppliers."
},
{
"post_id": "",
"author": "LaserSteve",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 13, 2025, 11:49:37 am",
"content": "This circuit was intended to be a \"high side\" driver so LDs could be stacked in arrays by laser hobbyists building their own laser projectors without having to insulate the outer cases of the LD cans. At the time it was created, red diodes were only 250 mw and were harvested from CD players.If you don't need high side drive, you can do much better with more conventional voltage controlled current sources.Watch for startup transients at power on.It's based on an obscure LT app note and 317 was not the output part.Nobody else ever got that to work .Steve"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 13, 2025, 05:04:17 pm",
"content": "Quote from: bschwand on February 12, 2025, 03:23:54 pmI think you really misunderstand people’s intent. Far be it from us to dissuade someone from building something, the forum absolutely encourages repair and DIY.Certainly, though, there’s a HUGE difference between “buy this component instead of that one” and “don’t fix that appliance, just buy a new one”. Unless you secretly have a semiconductor fab at home, then every IC you use will be purchased. (Assuming you’re not recycling salvaged parts, which brings its own can of worms…)However, there is also the issue of practicality: if you say you want to build a circuit designed by someone else, then your best chance of success is to build it as provided. The more changes you make — especially when we don’t know why particular parts were originally selected — the greater the risk it won’t work. So when one comes with a comparatively trivial roadblock of “I can’t get the parts\" (when you almost certainly actually could because they aren’t exotic, restricted, or obsolete), then it really begs the question whether it isn’t more sensible to just fix that issue, rather than go to the potentially huge effort of selecting alternative parts. (Even when one knows exactly why a given component was selected, finding substitutes can be quite daunting; doing so when we don’t know the original selection criteria, and in a circuit which is, let’s say,creatively misusinga common part well outside its specified specs, then it’s even harder.But this isn’t specific to you; this is how we’d approach anyone’s problem.It’s different if someone asks “I want to learn how to select a substitute part for this circuit because I want to learn.”"
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 14, 2025, 03:27:38 pm",
"content": "Quote from: LaserSteve on February 13, 2025, 11:49:37 amThanks, very useful feedback, it's good to know the background behind the circuit.I am looking into something more along these lines now (attached). That comes from the LT1492 datasheet."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 14, 2025, 07:06:12 pm",
"content": "I found a paper on a circuit that would probably be overkill but it explains well how it works, what to pay attention to and how to modify it.https://arxiv.org/pdf/0805.0015"
},
{
"post_id": "",
"author": "LaserSteve",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 14, 2025, 08:18:14 pm",
"content": "That one works. There are followup papers on it by other authors. You may need to scale up the current.Please consider a Lasorb (www.lasorb.com) to protect your diodes. I use them,know the company founder personally, and they work.Steve"
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 14, 2025, 10:05:30 pm",
"content": "About that circuit, my understanding is that the modulation input part only adds or substracts a small current to the current set through Vset.In my case, I want to define precisely the low state (as in a current just below lasing threshold), and the maximum current.In the original Libbrecht and Hall paper, they mention modulating the laser (for big current modulation) by altering the set point.So, I'd use 2 DACs like an AD5025 to define two different Vset, then use a voltage adder to present that to the current regulation AD8671 on its positive input. Then use a P-mosfet to connect/disconnect the output from the \"max\" Vset to the adder, and modulate that way my laser diode.Any comments on that scheme ?"
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 15, 2025, 12:22:39 am",
"content": "Quote from: LaserSteve on February 14, 2025, 08:18:14 pmThe LASORB component is interesting, would it work across LD modules that have strings of LD in series ?"
},
{
"post_id": "",
"author": "LaserSteve",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 15, 2025, 07:17:26 am",
"content": "One per diode.Its a patented combination of parts made on a wafer.There should be an appnote or two on the web site.Steve"
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 15, 2025, 10:41:54 am",
"content": "Quote from: LaserSteve on February 15, 2025, 07:17:26 amAh too bad. It wouldn't work for modules that have multiple LD chip in a package like those nichia laser projector modules. But good for those individual ones. good to know."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 18, 2025, 06:43:00 pm",
"content": "Any input about this scheme, does it sound reasonable, what should I pay attention to ?Quote from: bschwand on February 14, 2025, 10:05:30 pm"
},
{
"post_id": "",
"author": "mtwieg",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 21, 2025, 12:34:24 pm",
"content": "Quote from: bschwand on February 18, 2025, 06:43:00 pmSounds reasonable if you just want to transition between two configurable setpoints. I would suggest using an analog switch instead of a P-fet, but it's hard to imagine exactly what your proposed circuit looks like."
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 21, 2025, 12:57:29 pm",
"content": "Quote from: mtwieg on February 21, 2025, 12:34:24 pmwell my idea was to use a p-fet as a switch, to basically let it pass the voltage from one of the DACs or not into the adder op-amp, so the adder opamp would vary accordingly between two setpoint.Yes, I want to transition between two configurable setpoints, but do it fast and repetitively, at up to 5MHz.I did have the idea of using an analog switch instead of an adder and a p-fet, but are those able to be switched rapidly ? In my application I would select one or the other input at up to around 5MHz.I am also not sure how an analog switch goes from one to the other input, is there some down time or else ?I guess that is quantified by the capacitance and the ton/toff times only ? I guess I would want very low on resistance too. (I was looking at something like the ADG849https://www.analog.com/en/products/adg849.htmlor the SN74LVC1G3157https://www.ti.com/product/SN74LVC1G3157)"
},
{
"post_id": "",
"author": "LaserSteve",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2025, 04:14:05 pm",
"content": "W's page has been \"coming and going\" with regards to access, but take a look here.I've helped him with his Ion Laser Designs, he's good..https://hololaser.kwaoo.me/Aka W's Laser Project Page in Google Search, If you can't load them, head for the web archive.His driver designs are impeccable.Steve"
},
{
"post_id": "",
"author": "bschwand",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 21, 2025, 05:31:24 pm",
"content": "effectively the page is downHis requirements seem quite different from mine, but there is a lot of very interesting and useful information there, thanks for the link !Quote from: LaserSteve on February 21, 2025, 04:14:05 pm"
}
] |
2025-10-17T16:22:51.527060
| 35
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1mhz-oscillator-using-op-amp/
|
1MHz Oscillator using op amp - Page 1
|
[
{
"post_id": "",
"author": "mathk",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 18, 2013, 01:31:02 am",
"content": "Is it possible to design a 1Mhz sine wave oscillator using op amp?According to some App Note from TI it is only possible design oscillator up to a couple of Khz with op amp. But if you take high speed op amp like some Analog Device \"AD8055\" which have a slew rate of 1400V/us and a 300Mhz -3dB bandwidth I am wondering if we can design oscillator that goes up to a couple of Mhz with it?Also advice on designing such oscillator are more than welcome.Thanks."
},
{
"post_id": "",
"author": "c4757p",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 18, 2013, 02:40:14 am",
"content": "Try it!"
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 18, 2013, 01:01:00 pm",
"content": "Of course you can design a 1MHz oscillator with an opamp.One method might be a \"phase-shift oscillator\" (google it), the values are quite reasonable (220pF/300R) - i'm assuming that you want a simple oscillator with a sine out?"
},
{
"post_id": "",
"author": "JVR",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "February 18, 2013, 01:38:58 pm",
"content": "Just use a Xtal as a reference."
},
{
"post_id": "",
"author": "mathk",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 20, 2013, 01:21:15 am",
"content": "Yes @fcb simple sinusoid is what I need. I have try the \"Wien bridge oscillator. I set the frequency at about 900KHz but the problem is that I have more a square wave than a sine wave and the frequency is jumping from 950 to 960 KHz (measured with a rigor 100Mhz bandwidth scope).Then I tried a simple LC oscillator and the output is much cleaner, I still have a square wave but filtering the output give me what I need.Any suggestion to increase stability?Thanks"
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2013, 01:40:35 am",
"content": "It's in the nature of the Wien for it's amplitude to grow until clipping. You need some form of amplitude stabilisation - bulbs used to be used.Once you've sorted the amplitude out, then tackle the f-instability. Just be careful that it actually exists, and not some artifact of the Rigol."
}
] |
2025-10-17T20:25:56.809234
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1mm-squared-wire-to-2-54-pin-header/
|
1mm squared wire to 2.54 pin header? - Page 1
|
[
{
"post_id": "",
"author": "jwhitmore",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 07, 2017, 08:23:22 pm",
"content": "Hello All, I'm working on re-wiring a tractor. One of the computers has a plastic connector into which is inserted crimp pins. Now I have a strip of connectors which fit into this connector but they are from RC Model kit I have. I'm re-wiring the tractor with 1mm squared wire. I think that's more copper then would be necessary but that gauge is the most common and has the most insulator colours on the market.I'll attach a photograph, including both my strip of connectors and the crimp pin out of the tractor's connector. So I'm struggling to find a connector like this which will take 1mm squared wire. I think I'm struggling as this style of crimp connector probably has a name but I've no idea what it is. Can anybody shed some light on that. In RC modelling I think it's just a servo connector but that's probably not a universal term at all.Thanks for any and all help. I'll trawl through the thousands of connectors on farnell and who knows I might just stumble across the answer this time round."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2017, 08:36:45 pm",
"content": "You'll be very lucky to find anything like that. 1mm2wire is good for about 8A, more in free air, and there's no way a pin header connector like that is good for anywhere near the same current, so they are usually made to take significantly smaller CSA wire."
},
{
"post_id": "",
"author": "jpanhalt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2017, 09:27:43 pm",
"content": "There are two basic types of connectors for what you show. One uses a barb on the female part to retain it in the plastic housing. The other uses an a finger on the plastic housing that fits into an indent on the female metal connector. It looks like you have the latter type. The distance from the mating end of the connector to the indent can vary. I have my parts separated into short and long.There are lots of choices, and without actual dimensions, I cannot give you part numbers. The search is not hard.As a general comment, my tractor (Case brand) used Deutsch connectors for things under its hood. I have found my local dealer very helpful in identifying what I need, even if it doesn't have it. What brand, age, and size tractor is yours? Is it low current signals, like starting and pre-heat (diesel)?John"
},
{
"post_id": "",
"author": "langwadt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2017, 10:06:36 pm",
"content": "minifit jr. ?"
},
{
"post_id": "",
"author": "Nusa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2017, 10:52:37 pm",
"content": "Your RC connector strip is probably what is generically known as female \"dupont pins\", that usually go into 0.1\"/2.54mm spaced \"dupont connectors\". Those phrases will get you lots of search hits, anyway. They're typically specced for awg 22-28 wire (much smaller than 1mm) and 3A max.Your used connector looks larger than the dupont pins in the picture."
},
{
"post_id": "",
"author": "jwhitmore",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 08, 2017, 07:30:54 pm",
"content": "Thanks for all that, I've had a closer look at things and yes the connector I have is a good deal smaller then the one out of the tractor.Oh the Tractor is a 1997 New Holland 8360. I've not been able to gather much information from \"official\" channels but then I might be on the wrong channel or that tractor might be so old that it's no longer really supported. I'm not sure how the industry works.So I measured and the connector from the tractor is 6.2mm before the edge for locking against. Where as my RC \"dupont\" is only 4.5mm and taking a closer photograph shows that they are much smaller."
},
{
"post_id": "",
"author": "jpanhalt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2017, 07:47:10 pm",
"content": "That tractor apparently is still supported by CNH. Here is a link to its parts catalog:http://partstore.agriculture.newholland.com/us/parts-search.html#epc::mr52978Maybe you can find the part number and a picture and work backward. CNH is not nearly as big as JD, but it is fairly common in parts of the US.John"
},
{
"post_id": "",
"author": "jwhitmore",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 08, 2017, 07:59:00 pm",
"content": "My problem is that the smallest part is the wiring loom. The plastic connector and the crimp connectors which make up that connector are not really part of the parts catalog. Even if I went to the local dealer I'm not sure that they could help me. I did enquire about the wiring loom and was told that it was unavailable. That's why I'm trying to find the crimp connector."
},
{
"post_id": "",
"author": "jpanhalt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2017, 08:29:50 pm",
"content": "I happen to own a smaller Case tractor, and I know what you mean. Mice had done some damage to a wire and I could not identify the actual connector (turned out to be a Deutsch). I went to the dealer (it helps if you buy other stuff too) and spoke with maintenance -- not parts. We went out to the field truck and started looking at some of the pins for connectors. Found a match. Once I knew it was a Deutsch, the rest was downhill.Note: Your situation is not unique. No one, except maybe CNH, wants to replace a whole harness for a screwed up pin or connecting wire. The service truck is equipped for doing exactly what you are trying to do. The pins are not in the catalog, but if you have the name for the harness, it might help.Just looking at your picture, it might be a 0.156-pitch connector. Resembles Molex, but the pins look slightly tapered so it may be another brand. Anyway, that size or its metric close equivalent might fit.John"
},
{
"post_id": "",
"author": "Nusa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 08, 2017, 09:00:12 pm",
"content": "You might try calling a few tractor salvage yards (or visit if one is close) and see if they'll clip the right part of the harness from a parts tractor for you."
}
] |
2025-10-17T18:56:59.486313
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1n34-diode/
|
1N34 Diode Schematic included - Page 1
|
[
{
"post_id": "",
"author": "Aztlanpz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 29, 2018, 10:39:01 pm",
"content": "I need a replacement diode for a 1n34; digikey does mot Stock it ."
},
{
"post_id": "",
"author": "Bassman59",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2018, 10:46:26 pm",
"content": "Quote from: Aztlanpz on October 29, 2018, 10:39:01 pmYou know, Google and Bing and Duck Duck Go are your friends.Seehere.The 1N34 is an ancient germanium diode. What's your use? A fuzz box for guitarists?"
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2018, 11:25:18 pm",
"content": "There are no markings, but I have two diodes that I believe are ancient Radio Shack 1N34 diodes. They measure .235V forward voltage on my meter. See pic. If they look right, I would be happy to mail them to you. Of course they are not new, but are still functioning. I guess the big advantage of these is the low forward voltage, but I think there are also offsetting disadvantages."
},
{
"post_id": "",
"author": "ArthurDent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2018, 11:36:56 pm",
"content": "There are hundreds of listings for 1N34 diodes on eBay and they are dirt cheap. Also NTE has a cross referenced part, NTE109"
},
{
"post_id": "",
"author": "bd139",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2018, 11:52:28 pm",
"content": "1n270 usually works.A lot of the 1n34's out there are fake."
},
{
"post_id": "",
"author": "brybot",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 29, 2018, 11:53:42 pm",
"content": "https://www.amazon.com/Aideepen-10PCS-1N34A-Germanium-Diode/dp/B01KC0FNL8/"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2018, 12:02:47 am",
"content": "Personally, I'd give these a try. They have more convincing packaging and even show the data sheet with specs. Also cheaper!(More the fool me... I see bad comments in the listing I linked so I removed the link. Sorry...The one up above has a comment that says someone checked them on a curve tracer and found them good and really germanium...)"
},
{
"post_id": "",
"author": "Richard Crowley",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2018, 12:06:47 am",
"content": "Quote from: alsetalokin4017 on October 30, 2018, 12:02:47 amThey are still making them? Surely those can't be re-packaged NOS.NOS wouldn't have been ROHS, would they?"
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2018, 12:09:50 am",
"content": "Quote from: Richard Crowley on October 30, 2018, 12:06:47 amYou're too fast for me! I read the comments on the Amazon listing and also carefully looked at the diodes themselves... probably fake. Sorry..... I removed my link."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 30, 2018, 04:14:55 am",
"content": "How does the forward voltage drop of a germanium diode compare to a Schottky diode?I don't know which characteristics are important to the circuit but, AFAICT, the forward votage drops are similar.Post the circuit, it may not matter which diode you use. It could just be a really old design."
},
{
"post_id": "",
"author": "Aztlanpz",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 31, 2018, 03:54:06 pm",
"content": "Schematic"
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2018, 06:15:04 pm",
"content": "Given that the 2 diodes just work as a half-wave rectifier to turn on the transistor when the crystal starts oscillating, I would think any small signal diodes would work. Try 1N914 or 1N4148."
},
{
"post_id": "",
"author": "bson",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 31, 2018, 07:51:49 pm",
"content": "A 1V 1N4148 (they also come in 1.2V, but this may only be a difference in the current at which it's measured) -https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/1N4148TR?qs=sGAEpiMZZMudZehw8RjeZQwvkgSNJ%252b%2f0$2.20 for 100pc on tape."
},
{
"post_id": "",
"author": "bson",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 31, 2018, 07:56:41 pm",
"content": "Quote from: rstofer on October 30, 2018, 04:14:55 amThe 1N34 has a 1V forward drop and a 50µA reverse leakage, 1pF capacitance at 1MHz. A 1N4148 has a 1V (or 1.2V depending on which angle you look at it), 5µA reverse leakage, and 4pF capacitance. It's pretty much a straight drop-in replacement. The germanium will tolerate higher surge currents, but the TH 1N4148 can tolerate 4A for 1 second, and I doubt this tester will ever come close to this, just looking at what else is in it (small signal BJTs etc)."
},
{
"post_id": "",
"author": "johnkenyon",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 31, 2018, 08:00:44 pm",
"content": "Quote from: rstofer on October 31, 2018, 06:15:04 pmLooks more like a half wave voltage doubler to me, but like you said, any small signal diode would do."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2018, 08:48:57 pm",
"content": "Quote from: johnkenyon on October 31, 2018, 08:00:44 pmYou are absolutely correct, it is a Greinacher Voltage Doubler circuit:https://en.wikipedia.org/wiki/Voltage_doubler"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 31, 2018, 09:45:05 pm",
"content": "Quote from: rstofer on October 30, 2018, 04:14:55 amGermanium diodes have about a 25% lower forward voltage drop than common small signal silicon Schottky diodes.I have yet to find an application where a 1N270 would not work in place of a 1N34A and both are suitable for RF and switching applications."
},
{
"post_id": "",
"author": "Simon123",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 01, 2018, 02:16:00 am",
"content": "The modern 1n34 is similar to modern 1n60, which is schottky diode ...http://www.kdiode.com/admin/diotech_file/1N60~1N60P.pdfYou can try getting 1N5711, which is very fast and cheap schottky diode ..."
},
{
"post_id": "",
"author": "alsetalokin4017",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 01, 2018, 02:18:38 am",
"content": "Well... perhaps \"It depends\".An interesting exercise is to connect your Diode Check DMM (I'm using the Fluke 87-III) in series with another DMM in the mA range. Then check a bunch of diodes. First just check readings with the test leads shorted (to see the burden of the mA meter); in my setup the Fluke is indicating about 0.013V and the mA meter is indicating slightly over 1 mA. Now insert a diode and read the Vf at the indicated current. It appears that the Fluke is using 1mA as the current for the Vf determination.Test some Schottkys, some Si rectifiers, Si small signal diodes, and of course germanium 1n60 and 1n34A if you have them. (I was able to find two 1n270 pulls and they tested the same as my \"known real\" 1n34As in this test.)"
},
{
"post_id": "",
"author": "jh15",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 01, 2018, 05:36:34 am",
"content": "I just bought what was said to be 1n34 diodes from ebay.Description said true 1n34.They are clear glass with a whisker seen.Junk! they all tested around .8 .9, or many open volts on my 8960.Called black banded. The other ones marked red band not tested yet.They come in a screw top test tube package.I'll dig out my my Tektronix 575 curve tracer once I get the strength."
},
{
"post_id": "",
"author": "exe",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "November 01, 2018, 09:20:28 am",
"content": "I bought some \"germanium\" diodes from ali express, but I didn't figure out how to test them. They showed unusually low dropout (in the order 0.2-0.35V, don't remember as it was long time ago). But are they really germanium and not some small-signal schottky? AFAIK curves are quite similar.Given the price (they were very cheap) and condition (absolutely new unsoldered), I think it just can't be 1n34. Imho it's schottky. If I find them I'll try to make some curves."
},
{
"post_id": "",
"author": "IanMacdonald",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "November 01, 2018, 09:50:26 am",
"content": "In this application, stray capacitance and reverse recovery time are going to be more important than forward drop. I would have thought that the 1n914 would be ideal. Though, 1n4148 should do.Other point is that the LED driver, having no base resistor, is going to set a hard limit on the rectified voltage equal to its Vbe drop. This will load the oscillator heavily. Not sure if that is intended, but I would have thought not."
},
{
"post_id": "",
"author": "Alex Nikitin",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 01, 2018, 10:24:00 am",
"content": "The 1N270 is available new and should do just fine, also RF Shottky diodes, for example from the BAT15 series should be OK too.CheersAlex"
}
] |
2025-10-17T18:22:46.019840
| 23
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1n4007-blew-apart-like-fuse/
|
1n4007 blew apart like fuse - Page 1
|
[
{
"post_id": "",
"author": "algorithm",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 24, 2022, 10:07:52 am",
"content": "Been trying to repair a switch mode power supply. Just noticed that a 1n4007 diode was blown in twain like a fuse on secondary side. Hadnt seen that before. Does anybody have any ideas what I should suspect caused this? It was a catastrophic failure, took out a power transistor, a 1.6a fuse, I thought the bridge, but datasheet said it has 1v vf. And that diode. Im hoping nothing else. On the primary side I had cobbled a 4.7uf 200v cap using 4- 50v in series. And left the other cap in as I didnt have 82uf at 200v and it was within 20% on capacitance and acceptable esr I thought. But I really dont know what caused it. I guess bad caps but although the caps age was old they looked good. Unfortunately no schematic and its a busy board. Its for a jvc vcr."
},
{
"post_id": "",
"author": "algorithm",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 24, 2022, 11:49:57 am",
"content": "I think the diode was replaced, why I used a 4007 I dont recall, probably misinformation while googling and poor assumptions, emphasis on ass. But the diode replaced has this printed on it\"339\"What kinda diode do that be?It has .1xx drop on dmm."
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 24, 2022, 01:28:00 pm",
"content": "1N4007 is a very slow diode and it is not suited for power supplies. (especially reverse recovery time).If that other diode is <200mV (or even below 400mV) then it's almost certainly a schottky diode.Schottky diodes are usually very fast, which is good for SMPS circuits.https://en.wikipedia.org/wiki/Schottky_diode#Reverse_recovery_timeSchottky diodes can also be too fast, which leads to higher EMI, coupling issues and other nastyness.An old but very good read is \"AN25 switching regulators for poets\"Another good magic word is \"hot loop\". Put that in a search engine and read some articles."
}
] |
2025-10-17T17:08:58.946998
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1n400x-diodes/
|
1N400X Diodes - Page 1
|
[
{
"post_id": "",
"author": "glee",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 12, 2012, 09:15:21 am",
"content": "What is the disadvantage of using 1N4007 in place of 1N4001? That is, why does the range of 1N400X diodes exist? Isn't 1N4007 sufficient for all cases?"
},
{
"post_id": "",
"author": "Rerouter",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 12, 2012, 09:28:27 am",
"content": "while it is true that it effectivly does the same job just with a higher blocking voltage i would imagine that back in the 1970's-80's in ten-thousand of quantity i would imagine there would have been enough of a difference to warrent using a lower voltage one,or perhaps you want your diode to break down over a certain voltage, but at a higher voltage than was available with zeners at the time, from a rare spike event, (seen in some automotive instruments)"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 12, 2012, 11:06:31 am",
"content": "The 1N400X is so common that its used everywhere, including in applications where component selection is taken very seriously.In some products, where a 1N4001 was spec'ed for the original design, the paperwork required and rectification needed to change the component to 1N4007 can be quite expensive.So manufactures will continue to supply the parts even when better options exist. In some cases the manufacture may have signed a contract to product the component for 20 years or more as a condition for their product being chosen over competitors.The real question is..Nowadays, is a 1N4001 is any different to a 1N4007, or is it just the text stamped on the outsideThough they probably are different, as Rerouter pointed out, some applications rely on the breakdown voltage."
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 12, 2012, 02:06:07 pm",
"content": "I forgot how much because it's a while ago I measured it but there was a difference in Trr. The 4001 was faster if I remember wel. Maybe it is in the datasheet.4001-4004 are 15 pF and the 4007 is 8 pF but according to other datasheets they are all 15 pF and I can not find Trr in all three datasheets I Looked. Only voltage ratings there differ. For rectifiers I most times use the 4007. They are the same price."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 12, 2012, 03:33:44 pm",
"content": "You will finf Vf is slightly higher and dynamic resistance is higher for the higher rated units. This is unavoidable as to get the high reverse voltage you need to have an initial diffusion that is lower density, so that then the bulk resistance is higher to have a wider junction to withstand the high voltage. Not much difference, but is can be a 100mV at full current, which can be the difference between a long lived diode and a cooked one."
},
{
"post_id": "",
"author": "glee",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 13, 2012, 06:02:02 am",
"content": "QuoteOk, but this brings us back to the original question, right? Basically it seems you're saying that 1N4007 is a safer choice.I hadn't really thought about contracted supply and price differentiation in the \"old days\" before ubiquitous MIC production, or the change in Zener characteristics since then ... breakdown voltage could be an important consideration too, I see.QuoteOk, and to extend that idea, is there really added value in paying the difference between a reputable company branded 1N400X and a 1000-for-$10 Chinese supply?"
},
{
"post_id": "",
"author": "poptones",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 13, 2012, 07:06:57 am",
"content": "Well, I can remember one time having a product that used about 1000 diodes a box, so we went through lots of 1n4148s. And one time we got a production run that just wouldn't work right. Could not figure it out until we finally tested the diodes. Sure enough, every one just acted like a piece of wire.I don't know how common that would be now, though, since diodes are less than a cent and it costs 3.8 cents just for a 10cm piece of wire with header crimps on each end. There are lots of more efficient things to counterfeit than diodes."
}
] |
2025-10-17T20:30:33.643001
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1n4148-and-10r-resistor-in-parallel-any-way-to-test-diode/
|
1N4148 and 10R resistor in parallel, any way to test diode? - Page 1
|
[
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "December 15, 2018, 09:28:51 pm",
"content": "I was wanting to check some out of circuit diodes, but they are each paralleled with a 10 ohm resistor. Is there any fairly straightforward way to test if the diode is fine without splitting it from the 10R resistor? And to check the 10R hasn't shifted much? Thanks"
},
{
"post_id": "",
"author": "capt bullshot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 15, 2018, 09:39:10 pm",
"content": "You can check the 10R resistor using a common Ohmmeter, I suppose it'll apply a rather low current (like 1mA to 10mA). So the voltage across the resistor stays well below the diode forward voltage.For testing the diode, you could apply a constant current of 100mA that would cause 1V drop across the resistor. With diode in parallel, the voltage drop will be lower, approximately the diode forward voltage at 60mA ... 70mA (0.6V ... 0.7V)."
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "December 16, 2018, 12:00:19 am",
"content": ".... and the reverse voltage will be 1.0 VThe 1N4148 is a signal diode, not a power one, so it's important to keep the current down. 100mA is ideal."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 17, 2018, 08:29:27 am",
"content": "Quote from: capt bullshot on December 15, 2018, 09:39:10 pmC L E V E R"
},
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "December 18, 2018, 02:08:56 pm",
"content": "That works fine and will save me a lot of time, many thanks"
}
] |
2025-10-17T18:19:53.328218
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1n4733-zener-diode-datasheet/
|
1N4733 Zener Diode Datasheet - Page 1
|
[
{
"post_id": "",
"author": "sy",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 18, 2023, 06:37:58 am",
"content": "Hello, I am trying to use this diode to regulate at 5.1V as stated in the datasheet.I'm using a 15-20V DC supply with a 462Ohm in series with the 1N4733.The upper and lower current limits should be:I_upper=(20-5.1)/462=32mAI_lower=(15-5.1)/462=21mAWhich is less than the current specified in the datasheet of 49mA.Based on this I would have assumed, if anything, the voltage at the output to drop below 5.1V, but when I measure with a DMM the output is 8.59V? And leaving it there for a while it increases like +0.01V every second or two...I've checked if the diode could potentially be damaged, but it seems fine using the diode test on the multimeter.Can someone help explain this to me please?"
},
{
"post_id": "",
"author": "srb1954",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 07:34:17 am",
"content": "Quote from: sy on December 18, 2023, 06:37:58 amAre you sure that your resistor value is correct? You should not get up to 8.59V if the Zener is OK and the resistor is within a suitable range. If your resistor is too low the current through the Zener will be too high, it will overheat and its voltage will exceed its nominal voltage and may increase further as the diode warms up.What is the minimum and maximum current drain of the circuit connected to the Zener? You need to know these values before you can calculate a suitable dropping resistor."
},
{
"post_id": "",
"author": "PSR B1257",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 07:40:16 am",
"content": "Have you verified the marking on the diode?Have you checked the DMM against another DMM, or a more less known voltage source (e.g. 5V USB)How do you came up with a 462Ohm resistor (this value is not even part of the E192-series)?What kind of load do you want to supply?Why was a Zener Diode chosen? They are inherently inaccurate and also temperature- and current-depended."
},
{
"post_id": "",
"author": "Zenith",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 08:23:05 am",
"content": "Quote from: PSR B1257 on December 18, 2023, 07:40:16 amI wonder if it's a 1N4738, nominally an 8.2 Volt Zener, or a 1N4739. 8 and 9 can look like 3 with poor printing, or if the component has been handled a lot and the ink is worn.I'd be inclined to try another Zener."
},
{
"post_id": "",
"author": "sy",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 18, 2023, 11:42:30 am",
"content": "Quote from: Zenith on December 18, 2023, 08:23:05 amOMG thank you, I just double checked with others I had lying around and it is indeed a 1N4738.Quote from: PSR B1257 on December 18, 2023, 07:40:16 amI just measured one of the resistors I had lying around with my multimeter and it came up as 462OhmI'm just experimenting and learning to use them as regulators after reading through some book.What is the effect of temperature on the Zener diode? I noticed after touching the resistor it was quite hot (stupid idea). Would it have some effect on voltage creeping by like +0.01 I saw earlier...?Quote from: srb1954 on December 18, 2023, 07:34:17 amBecause, when I try the circuit the current draw is less than expected.Here is the new values:Dropping resistor: R=(20-8.2)/31mA=380Ohm (the one I used was around 375Ohm)However, the voltage drop across the terminals is approx 8.68V. I switched the diode out for a different one and got a different reading at 8.46V. Both times they drew only 27mA of current for the 20V input.I'm not too concerned about the later tested diode, however, with the first one it creeps outside the 8.61V range. Are there any potential concerns around this?Edit: actually it's kinda concerning xD Why is the voltage differing so much? +0.26V to +0.48V"
},
{
"post_id": "",
"author": "Zenith",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 01:11:03 pm",
"content": "As I recall, the rule of thumb for Zener current is that it shouldn't exceed 10% of the current required to have the Zener at its maximum dissipation, in this case 1000mW.I make that to be 0.1W/8.5V=0.0117A - about 12mA20-8.5=11.5 - the voltage drop across the resistor.11.5V/0.0117A=982R. The closest convenient value is a 1K resistor. I'd be inclined to make it higher, say a 2.7K.If you have a high Zener current, the Zener will self-heat and its behaviour won't be what you expected. If you have too low a Zener current, the characteristics are non-linear and subject to slight changes in the Zener current. Instinctively, there seems something wrong in a Zener being hot to the touch.Zeners have a lot of problems, such as being noisy and temperature dependent, but they are useful enough voltage references. They can be used as a constant voltage power supply, but it's a very crude approach.If you want a 5.1V supply, a 7805 regulator is cheap and a more obvious solution. If you want exactly 5.1V use a variable regulator where you set the voltage with resistors. If you only want a few mA and you want great stability, use a voltage reference such as a TL431."
},
{
"post_id": "",
"author": "PSR B1257",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 02:04:58 pm",
"content": "QuoteGot it, so not nominal 462Ohm but actual.QuoteNot really. As the diode gets hotter, the voltage decreases.QuoteThat's common for Zener Diodes. There are manufacturing tolerances to start with. And on top of that, there characteristic curves are not perfectly \"straight\". If you plot U=f(I) you get a certain gradient around the nominal Zener-voltage. As the current increases/decreases the voltage also increases/decreases.Hence the question, what circuit you want to supply?"
},
{
"post_id": "",
"author": "srb1954",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 07:51:48 pm",
"content": "Quote from: PSR B1257 on December 18, 2023, 02:04:58 pmZener diodes with nominal voltages above 6V have a positive temperature coefficient so the voltage willincreaseas the diode gets hotter."
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 08:01:46 pm",
"content": "Easy demonstration: put a Zener diode across a good DVM input, feeding it either from a good current supply or a voltage supply with appropriate series resistor.When you pinch it with your fingers, you can easily see the voltage change."
},
{
"post_id": "",
"author": "Jeff1946",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 09:35:20 pm",
"content": "For currents less than 100mA you might want to consider using a TL431. The voltage can be set with two resistors and is much more stable than a zener diode. Checked with Mouser cost about $0.41 for one or $0.33 apiece for 10. Definitely worth having some."
},
{
"post_id": "",
"author": "Messtechniker",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 18, 2023, 09:44:39 pm",
"content": "Quote from: srb1954 on December 18, 2023, 07:51:48 pmZeners have their sweet spot regarding tempco at around 6 V.Seehttps://en.wikipedia.org/wiki/Zener_diode"
},
{
"post_id": "",
"author": "PSR B1257",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 19, 2023, 07:48:23 am",
"content": "QuoteOff course, my bad"
},
{
"post_id": "",
"author": "rdl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 19, 2023, 03:15:54 pm",
"content": "I tried using a zener as a regulator years ago. I concluded a zener was not the best way to go."
},
{
"post_id": "",
"author": "Zenith",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 19, 2023, 05:42:59 pm",
"content": "Quote from: rdl on December 19, 2023, 03:15:54 pmI've seen it done with a few commercial products where they cheaped out completely. One was a mains adapter for a Sinclair calculator. As you say, not the best way to go, and there are better solutions that don't cost that much more."
}
] |
2025-10-17T16:43:34.996600
| 14
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1n5406-diode-suitable/
|
1N5406 Diode suitable? - Page 1
|
[
{
"post_id": "",
"author": "MisterD",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 18, 2020, 03:33:52 pm",
"content": "Hi,I'm building a portable bluetooth speaker with some 18650 batteries I had laying around.My circuit/components so far:Old 19v/4.7A laptop charger connected to a buck converter. I set the output voltage of the buck converter to 12.6V.The output of the buck converter is then connected to a \"3S\" BMS for my three 18650 cells in series.I connected everything and then limited the current on the buck converter to a max of 2A so the laptop charger could provide the current.Now when I disconnect the charger I think there is reverse current flowing/leaking to the buck converter: during charging I see a charging current of 1.xAmps, the charger is removed and I see a negative current of 0.2A.For that I salvaged a 1N5406 from an old powersupply and connected it between the buck converter (+) output and the BMS.According to the datasheet the Maximum repetitive peak reverse voltage is 600V at 3.0A.As far as I can see everything is working as it should (0Amps measured) but I noticed that the diode gets quite hot. I measured about 80°C (was drawing about 1.9A during a charging cycle).Is this normal behaviour? The datasheet lists an operating voltage - 50 to + 150°C. I'm just worried that once everything is in an enclosure the temp of the diode might get even higher?Perhaps I'm not using the right diode?Best regards,Jan"
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2020, 04:54:32 pm",
"content": "This diode has quite high forward voltage drop, so it dissipates a lot of power in your application. If you want less heat, you should search for a diode with a lower forward voltage drop. Maybe a schottky diode (but some of them have noticable reverse leakage).P = Vf * I. So if forward voltage is 1V and current is 1.9A, you have 1.9W of diode power dissipation (quite a lot)."
},
{
"post_id": "",
"author": "bob91343",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2020, 05:04:50 pm",
"content": "You can use a bigger diode or parallel a few smaller ones to reduce the temperature rise. Keep the diode leads short to allow heat to flow in them."
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 18, 2020, 05:10:36 pm",
"content": "Also notice, that a diode voltage drop lowers the voltage on BMS. So if voltage drop on a diode is 1 volt, then BMS gets 12.6 - 1 = 11.6V. And voltage drop depends on current. So you loose voltage precision. This is more like a workaround, better would be to solve the problem by changing buck converter or BMS."
},
{
"post_id": "",
"author": "not1xor1",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 18, 2020, 06:14:10 pm",
"content": "Quote from: MisterD on April 18, 2020, 03:33:52 pmyou could replace the diode with a PMOSFET. When the laptop charger is connected the TL431 cathode should be about 2V and bring the MOSFET in conduction."
},
{
"post_id": "",
"author": "not1xor1",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 06:31:06 am",
"content": "Quote from: not1xor1 on April 18, 2020, 06:14:10 pmR3 should be 10k (I've not simulated it - you can easily do that yourself)"
},
{
"post_id": "",
"author": "MisterD",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 19, 2020, 07:38:51 am",
"content": "Thank you all for your replies so far.Before I try to implement the solution provided by not1xor1: would the 1N5822 schottky diode be more suitable?It has a Vf of 0.52V, compared to 1.2V of the 1N5406. But then I guess the leaking current is 2mA vs 5µA for the 5822 and 5406 respectively. So not sure yet.What I noticed as well when I plug everything in:https://youtu.be/ydiBPQf9D90Any way to avoid the sparks when plugging the device in?This is the buck converter I use by the way:https://www.aliexpress.com/item/32247251105.html?spm=a2g0s.9042311.0.0.27424c4d6LYWwmBest regards,Jan"
},
{
"post_id": "",
"author": "klausES",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 12:20:15 pm",
"content": "After a buck converter, the diode 1N5406 could be a very slow diode when it heats up the diode."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 03:13:15 pm",
"content": "The schottkey diode should be better sited, because it is lower Vf. Even there 0.52 V is still relatively high - so better use a larger one or one with lower V_f, e.g. with lower voltage rating.The MOSFET circuit could also be build with an NMOS FET if the switching is at the ground side.The diode D1 in the circuit is not really needed as a separate part, there is already a diode insider the FET."
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 04:57:12 pm",
"content": "Vf of 0.52V is ok, but 2mA Ir is horrible (it depends a lot on temperature and reverse voltage, check datasheet for that, but still). If you want a diode solution, look for schottky with little reverse leakage."
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 05:11:15 pm",
"content": "Quote from: bob91343 on April 18, 2020, 05:04:50 pmNo, youcan'tshouldn't put diodes in parallel. They don't match well enough.Quote from: MisterD on April 19, 2020, 07:38:51 amThe 1N5822 won't leak 2mA because you won't have 40V across it. Look at the graph in the datasheet.Quote from: klausES on April 19, 2020, 12:20:15 pmThe slowness of the diode is not relevant since it only has DC applied to it.Quote from: Manul on April 19, 2020, 04:57:12 pmThere is no such thing, the reverse leakage is directly related to the forward voltage."
},
{
"post_id": "",
"author": "bob91343",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 05:16:28 pm",
"content": "Yes you can parallel diodes. The currents won't share equally but they will share, accomplishing the goal. A look at the forward voltage vs current graph will show the sharing isn't too bad."
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 05:25:46 pm",
"content": "Quote from: edavid on April 19, 2020, 05:11:15 pmCome on. There are differencies, just do some parameter search."
},
{
"post_id": "",
"author": "MisterD",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 19, 2020, 05:41:42 pm",
"content": "Thank you for all your replies (again!). Since fast charging is not that critical I might lower the max current to let's say 1A which would lower the temp of the diode as well.Any ideas how I can avoid the sparks when plugging the powersupply in? See youtube link I provided.best regards, Jan"
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 06:18:53 pm",
"content": "Quote from: Manul on April 19, 2020, 05:25:46 pmThere is no way to do a parameter search for leakage at a specified reverse voltageUsually it's only vaguely specified in a low resolution graph."
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 07:12:32 pm",
"content": "Well, but parameter search can give you the \"feel\" (don't know how to say, because of my lacking english) and then datasheet can give more specific info.So here is 1N5822 (diode 1) and I chose a random diode to compare B340AE (diode 2):Same max reverse voltage 40VDiode 1 Vf = 0.525V @ 3ADiode 1 max Ir = 2mA @ 40V @ 25CDiode 2 Vf = 0.47V @ 3ADiode 2 max Ir = 0.2mA @40V @ 25CIt is not easy to compare very precisely, but 10x less leakage must mean something. Also I'm saying this from years of experience, leakage is not simply proportional to Vf it is a complex result of die manufacturing process."
},
{
"post_id": "",
"author": "edavid",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 08:16:58 pm",
"content": "OK, I agree, the B340 looks great.Of course it's possible that a modern day 1N5822 would be better than the datasheet spec."
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 19, 2020, 08:50:50 pm",
"content": "Quote from: edavid on April 19, 2020, 08:16:58 pmAnd it can be even greater.PMEG40T30EPVf=450mV @ 3A typicalIr max 28uA @ 40V @ 25CI remember I used diodes from this series from Nexperia, they really leak little at low temp. It is surprising, how semiconductor technology advances."
},
{
"post_id": "",
"author": "not1xor1",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "April 20, 2020, 04:23:37 pm",
"content": "Quote from: Kleinstein on April 19, 2020, 03:13:15 pmyes... thanksI forgot to specify that the diode was drawn just to highlight the MOSFET body diodeI didn't mean any external diode"
}
] |
2025-10-17T17:51:41.879901
| 19
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1n6478-equivalent/
|
1n6478 equivalent - Page 1
|
[
{
"post_id": "",
"author": "multiplier",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 31, 2013, 09:37:28 am",
"content": "Hi there!I need a DIP Package diode which has the same characteristics as the 1n6478-84 series. 6478-84 is surface mount and can't be implemented on bread boards. I couldn't find any equivalent on my own. Can anyone out there help me?"
},
{
"post_id": "",
"author": "Rerouter",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 31, 2013, 09:42:50 am",
"content": "from what i can see (datasheet is pretty limited on any specs) its a 1A general purpose diode, so unless a more detailed datasheet is linked to, i would say a 1N4004 will suit as a replacement for the breadboard,"
},
{
"post_id": "",
"author": "multiplier",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 31, 2013, 10:03:05 am",
"content": "The thing is, this diode also works at 10 kHz. 1n4001-4007 series aren't fit for high frequencies."
},
{
"post_id": "",
"author": "multiplier",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "March 31, 2013, 10:08:30 am",
"content": "How about the specs on this page?http://www.vishay.com/diodes/list/product-88527/"
},
{
"post_id": "",
"author": "Rerouter",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 31, 2013, 10:31:20 am",
"content": "where exactly does it say that? 10Khz is pretty bloody slow, and just about every other spec including the capacitance matches up... as they are both standard speed general purpose diodes? neither is made for a fast recovery time?i also have used 1n4004's as clamping diodes for about 10Khz with no issue so I'm quite curious where you found your info?"
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 31, 2013, 11:49:28 am",
"content": "The 1N400x series have a very slow reverse recovery, which means they suck for rectifying 10 kHz. For clamping diodes, you don't care about reverse recovery, but only about turn on time, which is much better. So 'works at 10 kHz' is a bit vague.I don't see any turn on / off specs in the Vishay 1N6478 datasheet, so I wouldn't rely on it to perform any better."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 31, 2013, 12:25:54 pm",
"content": "If you want a slightly better diode use the UF400x series, which have a better recovery time, but are pretty much a drop in replacement for the 1N400x diodes. A little faster but still quite capable."
},
{
"post_id": "",
"author": "multiplier",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "April 01, 2013, 06:20:50 am",
"content": "All my observations are based on the response of the circuit while simulating in Multisim. A diode with a fast recovery time is required for rectifier application and the 1n4001-07 series miserably fails. I have no idea as to how the 6478-84 series worked, but it worked. MAX474 is the op-amp that I am using. I am facing the dilemma of finding a suitable DIP Package replacement for this series."
}
] |
2025-10-17T20:24:19.087827
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1pn-mcb/
|
1P+N MCB - Page 1
|
[
{
"post_id": "",
"author": "incognito1",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 29, 2020, 06:20:25 am",
"content": "For what applications, shall 1P+N MCB be installed instead of 1P or 2P MCB?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 29, 2020, 11:22:37 am",
"content": "When complete isolation is required, on a single phase circuit."
},
{
"post_id": "",
"author": "incognito1",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "September 30, 2020, 03:01:41 am",
"content": "when is it a must to install a 1P+N instead of a 2P?"
}
] |
2025-10-17T17:41:36.500461
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1s-lipo-chargerdischarger/
|
1S Lipo Charger/Discharger - Page 1
|
[
{
"post_id": "",
"author": "FrankT",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 20, 2017, 09:01:31 am",
"content": "I have a plethora of tiny 1s Lipo batteries from mini helicopters and quadcopters.I'm looking for a charger that can charge, discharge, and analyse them (voltage drop under load, max current, do they match their ratings eg 45C discharge), with low charge rates from 50-400mA.Before I start trying to build my own, I'm wondering if there is anything like this on the market, or something I can re-purpose - a general purpose charger, that I can reprogram.From what I have seen in sample schematics, I just need a simple buck converter circuit with current and voltage monitoring, and a microcontroller to manage the LiPo charge requirements. And a controlled load to discharge at various rates."
},
{
"post_id": "",
"author": "xani",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 20, 2017, 11:03:08 am",
"content": "I have this one:http://www.ebay.co.uk/itm/EverActive-LC-2100-Aku-charger-1-2-pcs-Li-ion-3-6V-3-7V-/122390498941It does charge/discharge and calculates battery ESR. Only 500mA/1A work so you'd have to modify it for smaller ones. I haven't teared down so I dunno if that has some dedicated chip or it can be easily hacked"
},
{
"post_id": "",
"author": "BradC",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 20, 2017, 01:00:44 pm",
"content": "I use a SkyRC IMAX B6. Does a great job.I wrote a little daemon that logs and generates a web page so I can monitor the unit from a web server.I use it for anything from small lead acids to my plethora of cheap RC lipos."
},
{
"post_id": "",
"author": "BenKenobi",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 20, 2017, 06:03:11 pm",
"content": "I use the same charger for all my LiPo's, it has been faultless, not expensive really either.Don't bother with some of the cheaper plug top 1s chargers, I've had batteries cooked by chargers that don't regulate or shut off properly."
}
] |
2025-10-17T18:48:41.557392
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1st-buck-converter-design-help/
|
1st buck converter design help - Page 1
|
[
{
"post_id": "",
"author": "trilerian",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 07, 2024, 03:06:18 pm",
"content": "I created my first buck converter circuit and I keep frying the buck IC. I created the design in TI webench, copied the schematic over to KiCad and then designed my pcb. The goal behind this was to be able to have JLCPCB assemble the boards for me. Normally I assemble my own boards, but due to amount these will be sold for, ie not much, I want as little as my own time in them as possible.So what is this? This is a power distribution block for 12V DC and 3x USB A connector for 5V usb devices. The idea is to plug the input into a 12V DC power supply, then you have 4 pair of 4mm connectors to power your chargers and other items for RC racing. A lot of racers complain that the cheap USB connectors they get don't supply enough current so I wanted to design my USB 5V with a buck converter that could supply high current.The webench design parameter was 8A and 5V, and it conveniently spits out a circuit for me. I then went through BOMs of the designs and chose one that JLC had the components in stock for, with the exception of the inductors. This was really the only change I made from the webench design. I chose a 2.2µH inductor instead of the 3.3µH in the design, however I did look at the datasheet of the TPS51396ARJER and it suggests a 2.2µH inductor for use.Long story short, the completed boards that JLCPCB sent me short the VIN as soon as power is applied. No load being applied through the USB connectors, it shorts on power up. The IC burns up with a little flame, and melts the solder mask above the traces (yes the IC is placed correctly). When I remove the component the short is gone. So there is not a short in the traces. This happened with all 5 prototype boards I got from JLC. Kind of expensive failure since this was done in 2oz copper and ENIG finish.I am attaching the webench design, my schematic, my pcb layout and the BOM.I hope this is some minor mistake I missed that can be easily fixed, thanks for any help.-Andrew"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 07, 2024, 03:43:44 pm",
"content": "Was the power supply already turned on when you connected it? If so, this might be classic “inductive kick” into ceramic input capacitors:https://www.analog.com/media/en/technical-documentation/application-notes/an88f.pdfDo you have any new ICs you can install? If so, then try adding a much bigger electrolytic cap (like 1000uF) in parallel to the ceramic input caps, and turn off the power supply before connecting it. If this powers up successfully then you have a decent idea what’s wrong. Then you can consider whether to fix it by adding series resistance, or a big electrolytic, or a TVS diode."
},
{
"post_id": "",
"author": "JustMeHere",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 07, 2024, 04:14:55 pm",
"content": "Those 2 pins that say NC but you have connect to ground could be the issue.Never mind, I see the datasheet says it's okay to ground them.Also make sure the inductor you choose has the right (something). I'm not sure what (something) is but the first buck converter I made wasn't stable and Vout was way too high. I swapped it out everything started to work. Maybe it's the resonant frequency."
},
{
"post_id": "",
"author": "trilerian",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 07, 2024, 04:41:49 pm",
"content": "Quote from: tooki on September 07, 2024, 03:43:44 pmWell that is interesting. And yes, the power supply was already turned on. I have connected those $1 Chinese buck converters up to the power supply while it is already turned on without issue. And they use ceramic input caps as well, figured I should be safe.I can order some more ICs and test though. I would like to verify that I didn't make any other mistake in the pcb design first."
},
{
"post_id": "",
"author": "trilerian",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 07, 2024, 05:21:50 pm",
"content": "Quote from: JustMeHere on September 07, 2024, 04:14:55 pmHere is the datasheet for the inductor I used:https://www.lcsc.com/datasheet/lcsc_datasheet_2108142230_KOHERelec-MDA1040-2R2M_C2847549.pdf. The datasheet for the TPS51396Ahttps://www.ti.com/lit/ds/symlink/tps51396a.pdf?ts=1725728959354&ref_url=https%253A%252F%252Fwww.mouser.com%252Fsays for 600kHz and Eco mode to use a 330kΩ and a 5.1kΩ voltage divider network for the mode pin. Which is what I am using, and later in the datasheet it says for 5V and 600kHz to use a 2.2µH inductor. Like I said, the webench design called for a 3.3µH inductor, but I made sure the resistance of the inductor I chose was lower than the webench design and the saturation current was at least twice what the buck IC could output. I would have just chose the same inductor as the webench design, but JLC didn't carry the inductor component from any of the webench designs."
},
{
"post_id": "",
"author": "Electrodynamic",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 07, 2024, 05:54:58 pm",
"content": "QuoteFor buck, boost and cuk converters I like to use cheap micro controllers like the Arduino nano.We can set the operating frequency with a timer on an output pin and monitor the output voltage and current using using input pins and interrupts.Like this,https://maker.pro/arduino/tutorial/how-to-build-an-arduino-based-buckboost-converterThe problem is what I call \"dumb electronics\" which don't have the ability to self monitor themselves. For example, I like to throw in a couple super cheap thermistors to monitor the inductor and switching mosfet temperature. If it ever exceeds my overheat set point it turns off. I also like to stage high power applications so as one inductor and mosfet becomes overloaded I can switch in another identical inductor/mosfet section to take up the slack. I do this because small ferrite toroids are dirt cheap and larger ones much more expensive. We can also add a $5 OLED display to monitor stuff which also helps.I would also overbuild the input and output buffer section which I found lacking on most electronics. They cheap out using undersized caps and any transients tend to wipe them out.I'm also into electric RC cars, airplanes and helicopters for about 30 years."
},
{
"post_id": "",
"author": "trilerian",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 07, 2024, 06:44:03 pm",
"content": "I ordered some more of the buck ICs. I'll do more testing, I have some electrolytics I can put on the VIN as well to test. Maybe the ICs were a bad batch, who knows."
},
{
"post_id": "",
"author": "trilerian",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 07, 2024, 07:25:28 pm",
"content": "I hooked my scope up to the VIN of the circuit and measure the voltage spike when flipping the switch on the circuit to turn it on while connected to a DC supply, probe tested at the positive side of C3. The Max Voltage was 28V. The IC I am using has a max VIN of 24V, so maybe after repeated use the 28V transient my destroy the chip, but I doubt that is the case for the pyrotechnics I got when power it up with the IC connected. It really acts like a dead short on power up.Here is the scope output."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 08, 2024, 12:16:54 pm",
"content": "Quote from: trilerian on September 07, 2024, 04:41:49 pmWell, cable length is a factor, as is the total input capacitance, as is the supply voltage, and you don’t know if the Chinese modules use a chip that tolerates bigger spikes. (FYI, I have blown up Chinese DC-DC converter modules this way. I now add an electrolytic in parallel with their inputs if there’s any chance they’ll be hot-plugged.)"
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 08, 2024, 12:18:05 pm",
"content": "Quote from: trilerian on September 07, 2024, 07:25:28 pmWell, once the chip is fried, you don’t know what all it shorts together internally. It very well could result in the failure mode described."
},
{
"post_id": "",
"author": "trilerian",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 08, 2024, 02:19:47 pm",
"content": "Quote from: tooki on September 08, 2024, 12:18:05 pmI added a 220µF in parallel, this was the biggest electrolytic I had laying around with a 25V rating. Attached is the scope shot of that hot powering up. This I think should definitely be fine. This is being made to be used with 12V DC supply, There is a little variance there like mine that is 14V, but even with mine this doesn't spike with that cap. So I will assume this will be good enough for testing. I can redesign the board with bigger caps for a safety margin. We'll see what happens when the parts come in I guess."
},
{
"post_id": "",
"author": "trilerian",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 28, 2024, 03:40:26 am",
"content": "Quote from: tooki on September 07, 2024, 03:43:44 pmJust wanted to say thank you again. I finally got the chance to get some of the ICs installed onto the board with the 220µF caps on the input, and I get 5V on the USB. So the design, aside from the bigger input cap is fine. Just to be sure I removed the cap and got pyrotechnics. All in all very interesting, and I guess a lesson learned."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2024, 11:29:18 am",
"content": "Glad it worked out, and was indeed a simple thing! And as a bonus, you learned something new that will be useful in your future understanding of electronics.Inductive voltage spikes are something that aren't intuitive (in that you don't even realize they would exist until someone explains how it works). At least that's how it was for me.(And thanks for taking the time to give an update, that often gets forgotten, but is much appreciated!)"
}
] |
2025-10-17T16:29:51.833592
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1st-fpga-cypress-cy7c68013a-128/
|
1st FPGA Cypress CY7C68013A-128 - Page 1
|
[
{
"post_id": "",
"author": "ashley.hughes",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 08, 2013, 07:47:28 am",
"content": "Hey all,I have been wanting to get a FPGA for a while but the price was off putting.I have found this on eBayhttp://www.ebay.com.au/itm/Cypress-CY7C68013A-EZ-USB-FX2LP-USB2-0-Develope-Board-Microcontroller-High-speed-/260871850279?pt=LH_DefaultDomain_0&hash=item3cbd2c8927#ht_2235wt_953I have purchased some other products of this seller that have worked fine.I know there is a big learning curve from AVRs to FPGA and they are used for different things. But for $30 if it entertains me for a few days money well spent and Im studying electrical engineering so I am sure it will come in handy eventuallyMy question is what software would I use to program it, as I believe the software packages aren't always free."
},
{
"post_id": "",
"author": "krenzo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 08, 2013, 08:59:28 am",
"content": "What makes you think that's an FPGA? Cypress' site says it's a microcontroller."
},
{
"post_id": "",
"author": "saigai",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "January 08, 2013, 09:29:09 am",
"content": "Here's a cheap bare-bones FPGA board, combined with an usb blaster. You might find them for even cheaper, if purchased separately.http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150961273878I have one, it works fine with the free Quartus Web edition. It has nothing special on board, just some leds and a button, but that's all you need to get started."
},
{
"post_id": "",
"author": "PA0PBZ",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2013, 09:41:04 am",
"content": "Not as cheap as the other alternatives, but with a lot of support circuitry on board and buffered I/O:http://www.micro-nova.com/mercury"
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2013, 12:00:22 pm",
"content": "That's definitely not an FPGA.It's the same MCU used in logic analysers such as Saleae and clones, although this one is mounted on a more featureful board."
},
{
"post_id": "",
"author": "DaveW",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 08, 2013, 12:31:47 pm",
"content": "For learning FPGAs, have a look at the Free Range site, they do an introduction to VHDL, a synthesizer & board,http://www.freerangefactory.org/site/index.phpI haven't tried their board, but the book is very good and the synthesizer is coming on nicely. If you just want a cheap FPGA board, have a look at the boards from Seeed Studios, very good prices for barebones FPGA stuff. Or if you'd rather go for something a bit more professional, the Terasic Nano boards are fantastic,http://www.terasic.com.tw/cgi-bin/page/archive.pl?No=593I used these with \"Rapid Prototyping of Digital Systems\" to practice using FPGAs,http://www.amazon.co.uk/gp/product/0387726705/ref=oh_details_o00_s00_i00"
},
{
"post_id": "",
"author": "ashley.hughes",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 08, 2013, 11:22:52 pm",
"content": "I was looking at the Mercury board a while ago off some one else's post on this forum.Also the Free range board looks nice as it comes with a book with some tutorials.Really depends on how much the postage will cost. Thanks for all the help and ideas"
},
{
"post_id": "",
"author": "HardBoot",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 11:39:46 am",
"content": "Xilinx, Altera... Who has the best free graphical logic design suite? Both do VHDL/Verlog no problem, but...I've quickly learned that describing what I want to do in VHDL is far too complicated because it's a mess of gate level stuff.My dream come true would be a more advanced form ofhttp://ozark.hendrix.edu/~burch/logisim/Which just happens to be where I sketched up some things I want to put into CPLD/FPGA."
},
{
"post_id": "",
"author": "deephaven",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 11:52:56 am",
"content": "Quote from: HardBoot on January 09, 2013, 11:39:46 amI can't speak for Xilinx because I've never used them. I've used Altera and am very impressed with their Quartus design suite. It is easy to create schematic designs and mix/match them with VHDL/Verilog if you ever wanted to. If you use a pre V10 copy of Quartus, it has a very easy to use simulator, so you can try out your design without any hardware. Later versions of Quartus provide simulator support but it is a steeper learning curve."
}
] |
2025-10-17T20:27:16.452841
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1st-ic/
|
1st IC - Page 1
|
[
{
"post_id": "",
"author": "insurgent",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 21, 2011, 05:34:31 am",
"content": "Just going through the old parts bins and came across the first IC I ever bough. I purchased it while in a Radio Shack with my grandfather (WWII Midway pilot and Ham radio operator) in Northern California having no idea what it was. It was also the same summer that Star Wars Episode 3 came out! Date code: Week 10 (February) of '73 (or October?)!"
},
{
"post_id": "",
"author": "smackaay",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 21, 2011, 06:14:12 am",
"content": "The first IC I ever got was back in like '85. Still have it. It was an LM566. Pretty cool chip actually."
}
] |
2025-10-17T20:40:03.973421
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1st-post-dead-24v-8a-charger-questions/
|
1st Post: Dead 24V 8A Charger Questions - Page 1
|
[
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 28, 2023, 02:04:54 am",
"content": "Firstly, Hi everyone! I've been following the channel for donkey's years & find myself in a situation whereby this newbies questions section is absolutely spot on! Thank you!tl;drIs there a good step by step diagnostic path for fixing dead power supplies posted anywhere?Cheers! Laz 😀A neighbour, showing unwarranted high expectations of my electronic prowess, has given me a mobility scooter charger (220V AC in, 24V DC at up to 8A out) to see if I can help.Mains fuse was rated 3A so I put a 13A fuse in to cover the 8A output. A 5A would've just blown. That's the three standard choices hereThe automotive blade fuse on the output is rated at 15A and is sound.(Would a 10A be safer? I think a 10A would blow earlier otherwise we're just relying on the mains fuse, no?)The thing is still dead but I've read it won't charge if the scooter's batteries are too low. But I would've thought it'd would at least show a power light even if it's not charging. Manual says red LED when charging going green at full charge. There's only one LED that has never lit.The next thing I'm going to do is unhook the 12V lead acid batteries, charge them with a bog standard car battery charger to barely 12V each, put them back in circuit on the scooter and test again to see if it is because the unit can see no charge that it appears dead.After that, it's me, a multimeter & a winning smile!Does anyone know of a step by step diagnostic path laid out either in text or video that you'd recommend?My meter reads capacitance but I was thinking of getting an LCR TC1 ESR tester so I can test the caps in circuit.I opened the ends of the charger up & it passed the soot & sniff test but it's going to be fun opening the thing. Where the main board is meant to slide out on runners built into the extruded aluminium housing it's been sealed in with lashings of rubbery mastic ☹️.Oh! It's a Strident CHE24-8 just in case anyone knows the beast & can tell me if that single LED lights upon application of power without being plugged onto the scooter.Apologies for the ramble and it's even helpful just writing down where I'm at.Thanks chaps!Laz 💜☮️😎"
},
{
"post_id": "",
"author": "darkspr1te",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 28, 2023, 05:38:48 am",
"content": "First rule off eev forums, thy shall test voltages :-)Jokes aside, i would look up SMPS repair videos as most chargers are a SMPS and voltage/current controller combined , Learn electronics repair channel does some great videos on it and could do with the views (they being botted by unknowns and loosing revenue)remember you are working with mains voltages here so if you cant be careful then dont attempt it.As a old dog in the \"you work with computers can you fix this\" circles i find first i always do the sniff test across the board, dry or leaked caps will often have a slight metallic smell close uplook for obvious signs of heat on all sides of the board, look for dry joints on large and small components.good luckdarkspr1te"
},
{
"post_id": "",
"author": "darkspr1te",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 28, 2023, 05:42:35 am",
"content": "I just did a quick check on google and if you search for \"24v mobility scooter charger schematic\" you will get a couple of diagrams that look very close to your unit. which btw is same psu that my Till machine in the shop uses, i've only ever seen a green light but there is no doubt it's the same.darkspr1te"
},
{
"post_id": "",
"author": "Shonky",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 28, 2023, 06:32:19 am",
"content": "Quote from: Lazarus42 on September 28, 2023, 02:04:54 amDo not replace the 3A mains fuse with a 13A fuse if that's the fuse on the primary side of the power supply.8A output at 24V does not mean 8A input current at 220-240V."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2023, 06:44:54 am",
"content": "Identify the chips, look up datasheets, study theory of operation and example schematics.But if you are making tihs sort of mistakesQuote from: Shonky on September 28, 2023, 06:32:19 amthen I don't know if you should be touching mains powered electronics."
},
{
"post_id": "",
"author": "Eraldo",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 28, 2023, 08:13:22 am",
"content": "Check the full bridge rectifier in the primary side for possible shorts. Check on the internet how to test those. If that is fine, then check the switching transistor/mosfet. Go to the datasheet and check if it's a transistor or mosfet and test it accordingly. It shouldn't be hard to locate it since it will propably be stuck on a heatsink.As someone else said, replacing the 3 amp fuse with 10 A one or more is dangerous and the actual current passing through that fuse is more like 1 Amp"
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 28, 2023, 09:02:58 am",
"content": "Quote from: Lazarus42 on September 28, 2023, 02:04:54 amCheck the physical conditon of the cable and connector wiring, they are probably the bits most at risk of failure. As others have said, put a (good) 3A fuse back in the plug - you didn't say whether the original was blown, which would indicate a primary side fault.If your neighbour is 'showing unwarranted high expectations of your electronic prowess', be very careful. Their house insurance company would almost certainly come after you if it, the scooter and the house go up in flames (a possibility if you start by putting over-rated fuses in). Never be afraid to do a few simple physical and voltage checks and report that 'this is beyond my ability'. Being a helpful neighbour can easily lead you out of your comfort zone."
},
{
"post_id": "",
"author": "snapper",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 16, 2023, 07:28:01 pm",
"content": "I love people who start a new post here, text a lotand then never get in touch again"
},
{
"post_id": "",
"author": "u666sa",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 17, 2023, 04:14:13 am",
"content": "Quote from: Lazarus42 on September 28, 2023, 02:04:54 amTake lots of hi-res a lot of light pics.Fuse you replaced is one thing, there should be another fuse soldered in. Plus you gotta check bridge rectifier."
},
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 26, 2023, 09:24:58 am",
"content": "Quote from: darkspr1te on September 28, 2023, 05:38:48 amThank you for taking the time to put these posts together. It's hugely appreciated.I discovered the Electronics Repair Guy already & I started at his first video taking things step by step. Such a shame some nasty, probably jealous, troll is giving him grief. He's been invaluable in enabling.e to catch up with modern equipment & materials. Things have moved on a lot since I was building HF Heathkit sound processors and ATUs with glorious air gapped variable caps that are a pleasure to use as kinetic art! That they enabled me to pull in Australian HF ATC on a long wire when I'd planned to start with a very basic setup and as I learned more I'd be able to hear further & further. Australian oceanic routes was my first \"catch\" on that enamel wire tensioned with bamboo canes. When a seagull hit the thing it made one hell of a twang (a Brixham hazard) but that was half way around the globe, first try. I couldn't really get much further! 😆Anyway, that was my grounding. My trusty Antex is now replaced by a T12-952 & the new liquid fluxes have blown me away! Solder now flows beautifully. I invested in some light & magnification as tracks and surface mount components are so small & I've got 60 year old eyes now! 🤓I told my neighbour the charger was stuffed & replaced it exactly from AliExpress. So now I've an item to learn about with no pressure from hopeful neighbours.I know enough to stay safe. Discharging caps after it's been energised, making sure I have good quality probes on a meter Dave recommended on his channel a while ago. Auto ranging too!I think it's the availability of boards from China that has impressed me most. Costs for charging protection and solar down in pence if you buy 10 of something you might only need one of but once you've paid postage... I'm replacing small lead acid and chunky alkaline blocks with 18650s and some stunning little USB + solar charging boards.Things last longer, the sun making a distinct difference and things I take camping are now loads lighter and more efficient.Oops, I'm waffling. I just wanted to say thanks for worrying, I've listened and that's why I've started at the begining of electronic repair from the proper Isle of Dogs, Gran Canaria. (Canaries being named after the dogs on the island left there by sailor's, not the islands named after the birds. And taken any urgency away from what is a steep learning curve.Thanks again mate 😀☮️"
},
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 26, 2023, 09:49:19 am",
"content": "Thank you for taking the time to reply. I listened & not only have saved some calculators but also I'm practicing changing the triangles into formulas, plugging in some numbers and working them out properly instead of relying on the automation.Here's a page that has helped a lot!https://caravanchronicles.com/guides/understanding-watts-amps-volts-and-ohms/"
},
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 26, 2023, 09:59:32 am",
"content": "Thanks for the pointers about mosfets. I've been following an electronics repair course from the beginning so have plenty of information on how they do what they do and also places to track down datasheet .PDFs.And re: your warning about my error in the rating of that fuse. I'm learning how to turn triangles into formulas and working through examples given, some I made up and mostly from irl by looking at alliances of all types around my home.I'm getting there, taking it slowly and carefully.I appreciate you taking time to write and tell me where I was in error. Without that step there can be no learning.Thanks mate 😀"
},
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 26, 2023, 10:07:58 am",
"content": "Thanks Gyro, yes I agree wholeheartedly. That's why I told my neighbour it was beyond economic repair so I ordered the right charger with the right connector from AliExpress. He's chuffed that he has a charger that works for a substantial saving on what the mobility shop tried to sell him (disability is like golf, just the addition of the D word or the G word attracts a 100% mark-up on normal prices!Plus, I now have a project that I can take the time to learn about safely with no pressure from eager neighbours and all the kit in the house is mine.Thanks again Gyro, keep safe mate 😃"
},
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 26, 2023, 10:19:40 am",
"content": "Quote from: snapper on October 16, 2023, 07:28:01 pmWho's that then Snapper? 🤔 What a thoughtless oik they must be eh? I missed who it was because I was in hospital for a bit. Still putting bits back together after sepsis. (Lost a couple of legs, open heart surgery, 50% kidney function and a diagnosis of Asperger's that I'm actually pleased about!)But! From being given three days at one point I'm just pleased I'm here! It's quite the perspective shift!I do like your screen name, Snapper by name and snappy by natu... Ahem, erm... If you spot the thoughtless git point him out mate! 😆Keep safe Snap,Laz 😎☮️"
},
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 26, 2023, 10:28:59 am",
"content": "Quote from: u666sa on October 17, 2023, 04:14:13 amThanks mate, the bridge rectifier. Rough & ready, make sure it's putting out DC. I have no scope so checking for full wave or half wave is a bit out of reach. But I could make sure all the diodes are working as one way valves (maybe gates, valves is used elsewhere in electronics eh?) and if it's a discrete component instead of four I could desolder it and use the LCR-T4 perhaps & check the forward voltages... am I on the right path there?Thanks for the tips, much appreciated 😃"
},
{
"post_id": "",
"author": "killingtime",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 26, 2023, 11:06:24 am",
"content": "First step would be to post some hi res pictures of the psu top and bottom with the cover off. We can then tell you which components to check. There are some basic checks you an make with a DMM that will tell you if the PSU is an easy fix or a write off, like checking onboard fuses, diodes, mosfets, capacitors etc. Always start with the simple checks first.Be careful when handling the pcb if it's a switch mode psu. The electrolytic smoothing caps on the primary side hold lethal voltages for a while after the psu has been disconnected from mains. They usually have bleeder resistors across them and are fine to touch after a few hours, but we don't know if the mfr installed them. If in doubt, short these caps out with a screwdriver or long nose pliers just to be sure."
},
{
"post_id": "",
"author": "Lazarus42",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 26, 2023, 12:15:58 pm",
"content": "Thank you! I'll set it up with some good lighting tonight.And yes, I've a healthy respect for all capacitors. Even if something has been sat for a while I'll short across them.My Dad used to work in the Torvac Room at S.T.C. (Standard Telephone & Cables later ITT) in Paignton, Devon metalising mylar sheets with aluminium under hard vacuum. (The grease that machine used was great for sea fishing reels!)Then he'd slit the sheets up and they'd get rolled up, held with a bit of yellow tape before the terminals went in & they were compressed & potted. Red & green little caps ended up on my Nan's Xmas cakes. And the rolls of metalised mylar, all light and floaty, made brilliant Xmas decorations!Plus, bigger rolls would get sent up on kites dangling for hundreds of feet... It wasn't until later that I realised I'd been flying chaff! It must've lit up the radars of the boats in the bay!So yeah... Caps have een a part of my history since the early seventies! Standard's Xmas trips for the kids of the workers.It's not there anymore. Housing estate and industrial estates now cover what was once the biggest employer in Torbay I think.Amazing the charge those rolls of mylar & aluminium can hold!Heh... Sorry mate, waffling. There's not many places that I wouldn't just get blank looks if I talked about this. I was diagnosed with Asperger's recently & I keep noticing stuff that fits. It's been quite the time for \"Oh! No wonder they thought I was a bit strange sometimes! 😆I'll have a bash at those photos tonight mate...Cheers!"
}
] |
2025-10-17T16:46:24.416688
| 17
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1st-project-with-help-from-forum!/
|
1st project with help from forum! - Page 1
|
[
{
"post_id": "",
"author": "raspberrypi",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 04, 2017, 08:10:58 am",
"content": "I started watching these videos last spring then joined the forum last fall. I went from almost no knowledge of electronic to building this:It takes a 5-35 VAC/ DC Connection and makes a fine tune adjustable 2-22VDC @ 1A, through the magic of an LM317 which is not a mosfet.I beefed up the parts above spec, added a fine tuning pot for voltage a big heat sink, and indicators that change brightness with output. One stays constant so you can reference a rough voltage your getting out.This forum was a huge help! Now I can power any small electronics with just about any linear wall power supply."
},
{
"post_id": "",
"author": "ebastler",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2017, 04:45:03 pm",
"content": "Well, congratulations on completing your first homebrew electronics project!A few suggestions for tweaking the build, or for your next project:I would recommend using heatshrink tubing for the three connections to the LM317 (isolating each one individually), instead of the hot glue you have applied. If these wires should short against each other, or against the heatsink, that could cause the full input voltage to show up at the output, killing your connected load. Better to play this safe!A similar suggestion regarding the rectifier PCB: Is its bottom well-insulated, or could it short against anything (e.g. the input jacks) if it moves around? Also, I can't see a big capacitor behind the full-wave rectifier. Is there one hidden underneath? The one on the vertical board seems a bit small. The LM317 will do its best to keep the output voltage stable even if its input has AC fluctuations, but the rectifier and capacitor need to at least make sure that the unregulated voltage never drops below the minimum needed to provide the desired output voltage. Do you have access to a scope to check the ripple (AC component) on the voltages?When using the power supply with a high input voltage, low output voltage and significant current, you probably have to keep an eye on the internal temperature. At 30V input, 5V output, 1A current, the heat sink would have to dissipate 25W. The heat sink seems to be fully enclosed in the case? In that configuration, it would probably get quite hot quicky, since the heat can't go anywhere. Bench power supplies often have the ribs of the heatsinks arranged out in the open, on the back of the enclosure; or they use vents in the enclosure and often a fan for forced air flow.Finally: One thing you have probably learned from this project is that mounting and wiring up the various independent components -- multiple PCBs, input and output jacks, potentiometer, regulator and heat sink -- tends to take a lot of time, can be a hassle, and is error-prone. As you gain more experience with the circuits you design, it pays off to plan ahead a bit further: Think about the arrangement of components in the enclosure, arrange them all on a single PCB (where it makes sense -- there are many well-justified exceptions to that recommendation), think about how to attach your PCBs to the enclosure etc..But that's for your next project! Have fun with your LM317 supply, and with whatever you build next!"
},
{
"post_id": "",
"author": "Electro707",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "March 04, 2017, 09:09:58 pm",
"content": "When you said:QuoteRemember that the input voltage must be higher than the output voltage by ~3v as stated in the datasheet.Regarding temperature the IC(The LM317 is considered an Integrated Circuit) has a over temperature and current protection built in so the chip should save itself in case you try to pull too much or it overheats.I recommend that you keep the input-to-output differential voltage between 4-7V as the chip heats up quicker as the difference is higher.Nice project for a beginner as you had no previous experience. The only you'll get better is by trying and experimenting.Anyways good luck with future projects, and remember we're always welcome to help you."
},
{
"post_id": "",
"author": "raspberrypi",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "March 08, 2017, 04:25:42 am",
"content": "You cant see it but there is a huge cap (1\"X 3/4\")just under the bread board, thats at a higher (almost double) uf value in the schematic with the exception of the lm317 every connection is heat shrunk and the bottoms of the boards and after I took that pic everything else is coated and secured into place with silicone, LOTS of silicone, almost like its potted and could probably survive a quick dunk under water. I accidentally shorted the leads of the cap right before I started sealing everything in silicone and the leads started smoking the insulation of a near by wire touching them but the LM317 and everything else was ambient temperature. I got kind of impatient with the last step which was putting the lm317 into place, hence the hot glue. I don't plan on using it run anything near 1 amp load, it mainly just runs really simple led circuits and is for testing things. Everything I tested doesn't even make it warm. The only part the gets warm (maybe 10'C hotter) is the resistor that powers the power on indicator LED. The heat sink is really just there to buy time when I accidentally short something, as happened once when I dead shorted it for about five minutes until that whole heat sink was well over 100'C and started melting wires touching it. Without it the lm317 would have been cooked. That thing it pretty robust."
},
{
"post_id": "",
"author": "JRosario",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "March 16, 2017, 11:28:59 pm",
"content": "Quote from: raspberrypi on March 04, 2017, 08:10:58 amGreat to see other people having some success. Very encouraging!Each project I start, I go in with a lot of optimism, but the plan often falls apart into frustration.I just got back on the forums looking for some encouragement, and I thank you for that."
},
{
"post_id": "",
"author": "james_s",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 16, 2017, 11:50:29 pm",
"content": "Quote from: JRosario on March 16, 2017, 11:28:59 pmWhere are you getting stuck?When I was a kid I had a lot of frustration trying to build things because although Radio Shack had a lot of parts still, they never seemed to have everything needed to build much of anything. These days with Digikey, Mouser, ebay, etc this is rarely a problem anymore."
}
] |
2025-10-17T19:00:45.428794
| 6
|
electronics
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beginners
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https://www.eevblog.com/forum/beginners/1v-reference-1ppm/
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1V Reference @ 1ppm - Page 1
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[
{
"post_id": "",
"author": "Rafael",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 26, 2019, 12:22:53 am",
"content": "Hello,Does anyone have any suggestions on how to find / build a 1v @ 1ppm reference?Thanks a lot!"
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 12:45:42 am",
"content": "Quote from: Rafael on January 26, 2019, 12:22:53 amI assume you mean: 1ppm/°C. Over what temperature range???"
},
{
"post_id": "",
"author": "Rafael",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 26, 2019, 12:50:25 am",
"content": "Quote from: Wimberleytech on January 26, 2019, 12:45:42 amYou're right, sorry to forget this detail.Range, around 23°C... I can imagine a hard task!Thanks!"
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 12:50:56 am",
"content": "Quote from: Rafael on January 26, 2019, 12:22:53 amhttps://www.apexanalog.com/resources/products/vre3050ds.pdf"
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 12:53:14 am",
"content": "Quote from: Rafael on January 26, 2019, 12:50:25 amYes, it is challenging. You must curvature compensate a bandgap reference...and pay attention to EVERYTHING.Solution: Buy it. I posted an example product.If you limit the range of temperatures (\"around 23°C\"), you do not have to do curvature compensation."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 01:07:03 am",
"content": "I have used quite a few of the MAX6350 & 6341 (5 & 4.096V 1PPM/C) on different jobs very good initial accuracy and stable over time but can still be tweaked if needed. One was a Mercury Button Cell (1.35V ) replacement for an old HP anchor I own. Buy some good quality Vishay or similar resistors (low temp co) and divide it down.https://www.eevblog.com/forum/testgear/hewlett-packard-740b-dc-standard-digital-voltmeter-(and-740a)/msg1438536/#msg1438536"
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 10:45:27 am",
"content": "Quote from: Wimberleytech on January 26, 2019, 12:50:56 amNice device, but the price: £138UK Ouch"
},
{
"post_id": "",
"author": "Wimberleytech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 01:47:05 pm",
"content": "Quote from: spec on January 26, 2019, 10:45:27 am...you gotta pay for precision! The Maxim parts are much cheaper."
},
{
"post_id": "",
"author": "mycroft",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 05:17:40 pm",
"content": "Many, many years ago, i read an article by NBS (now NIST) on using a mercury cell as a voltage transfer standard. The major problem was temperature sensibility. I would like to find this article again. I searched a lot without success. Anyone remembers this article and has a reference?"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 05:52:49 pm",
"content": "Quote from: mycroft on January 26, 2019, 05:17:40 pmNot the article you wanted but some of us still have some Standard Cells and play with them from time to time.https://www.eevblog.com/forum/metrology/1000-my-(hi)story-of-the-weston-cell-of-the-volt-and-of-being-a-volt-nuts/msg1039421/#msg1039421I had mine out of the boxes a couple of days ago in 35 degrees ambient. It was 0.06mV up on last time I recorded it at about 20C and some of that drift would have been the 34401A. The un-saturated ones had a better tempco than the saturated ones. Generally run in banks and averaged when used as references too.EDIT: NIST is currently offline thanks to the USA shutdown BS but try this search on Google 'nist weston standard cells' will get you some pdf hits when it gets back up."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 10:02:56 pm",
"content": "Quote from: Rafael on January 26, 2019, 12:22:53 amHi Rafael,I couldn't find a 1V voltage ref to meet your spec, so the only option is a higher voltage voltage ref, say 1V25, two resistors, and a precision opamp.You could make a miniature oven quite easily and pop the whole circuit in the oven to improve the stability with ambient temperature changes.As you no doubt know, the power supply would need to be pretty fancy, but all within practical bounds.How much current would you want to draw from the 1V reference?By the way, I am no expert on extreme high-spec voltage references, so these are just my thoughts.If you are interested in this approach, just say and we can discuss it some more."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 10:17:23 pm",
"content": "Quote from: Rafael on January 26, 2019, 12:22:53 amThere is a lot of information in other threads on this forum, in the metrology sub forum.Voltnuttery is expensive, very expensive.But your question is easy to answer - but is it the right question? Hint: state your problem, not your presumed solution. For reasons, seehttps://entertaininghacks.wordpress.com/library-2/good-questions-pique-our-interest-and-dont-waste-our-time-2/"
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 10:19:19 pm",
"content": "Quote from: beanflying on January 26, 2019, 05:52:49 pmI can use my working 1949 Weston standard cells as a thermometer, 40uV/°C"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 10:26:32 pm",
"content": "Quote from: spec on January 26, 2019, 10:02:56 pmIf it is a 'reference' the answer would be as little current as possible to maintain voltage stability. Op amp buffers can be added but generally they add to errors and tempco problems not help.There is for example a 0.01mV variation on my HP735A Transfer Standard between 10M and the GigOhm impedance settings on my 34401a so if it is being used as a transfer it has to be set to allow for this depending on the intended use. So load matters even if tiny."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 10:38:35 pm",
"content": "Quote from: beanflying on January 26, 2019, 10:26:32 pmYes, I do appreciate that that is a very specialist area and that 1ppm is only 1uV in 1V, so what I was going to do was to do the best I can and knock out a circuit and some notes for discussion. To my mind, the opamp is the biggest problem because choppers would be too intrusive."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 10:53:33 pm",
"content": "The Maxim Ref I pointed to earlier in the threadhttps://datasheets.maximintegrated.com/en/ds/MAX6325-MAX6350.pdfis about 1ppm/mA typical (seems to be correct from my testing) so a 10k total divider would keep it fairly close to that or better and if you fit up the extra pot shown on the datasheet it can be tweaked up if needed without needing an op amp."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 11:14:03 pm",
"content": "Quote from: beanflying on January 26, 2019, 10:53:33 pmI was thinking on similar lines after you said that the loading would be very low. Will have a look at your suggestion.If you had a 1V25 precision Vref (the lowest extreme precision voltage you can get), and connected a precision 250R and 1k resistor across it, as a potential divider, that would produce 1V with a source resistance of 200R (taking the source resistance of the Vref as 0R), which would mean that a 200M load would only result in a delta V of 1uV or 1ppm, all other things being equal that is."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 26, 2019, 11:42:58 pm",
"content": "Quote from: beanflying on January 26, 2019, 10:53:33 pmOK had a look at this. To have a 10K potential divider to produce 1V from a MAX6325 (2V5), would require 6k north and 4K south. This would give a source resistance of 2k4, which would mean (ignoring the MAX6325 for the moment), that the minimum load for a 1ppm voltage delta would be 2G4.I have also been thinking about the OP's requirement of 1ppm/deg C. But the specification we need is what voltage delta is acceptable over what temperature range and with what delta loading resistance, if there is a delta load- perhaps the load is fixed, which would simplify the design a bit."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 12:01:46 am",
"content": "Quote from: Rafael on January 26, 2019, 12:50:25 amAre you concerned about drift over time? If so, you may need lengthy burn-in times."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 01:42:13 am",
"content": "Without wanting to go way down the rabbit hole of voltnuttery a full and complete spec of the OP's requirements would be needed or we are just speculating on the requirements outside the 1V @ 1ppm of ? (voltage, temperature, drift over time etc) and what is the references intended use? So some more info is really needed.Just run over the rough numbers based on the 10K guess I used this morning. -To get the divider of 6 and 4k (assumed dead accurate) you would actually get 0.9996 volts read assuming the nominal 2.5V 10Meg meter so it would need the compensation pot fitting to the circuit to tweak it accordingly if it's purpose is for calibration and if not the input impedance of the driven circuit needs to be taken into account regardless.My couple of tweaked MAX 6350's I built have remained within spec and have been powered on now for over a year so they seem to hold up well after the first week or so of settling. There was some questions raised about the epoxy version available (ceramic is off the market) could be susceptible to moisture over tim but that is well into VoltNuttery @ Andreas level territory (nothing wrong with that at all btw)"
},
{
"post_id": "",
"author": "ArthurDent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 02:30:58 am",
"content": "I appreciate the irony that someone asking about precision voltage has a tag line of \"LTZ1000 for voltages\""
},
{
"post_id": "",
"author": "Rafael",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 27, 2019, 03:17:20 am",
"content": "Quote from: tggzzz on January 26, 2019, 10:17:23 pmThanks a lot for all answers... As a beginner, I need to learn a lot before try some adventures in Metrology section.I have an old russian voltmeterhttps://www.eevblog.com/forum/beginners/31-voltmeter-sch-31-nixie-russian-voltmeter/and I need to calibrate it with 1v reference.@ArthurDent, I really really admire the precision that the component can generate, but for 1V, it gets a little further.edit: Or maybe the answer? Please, be gentle with me..."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 04:08:55 am",
"content": "Nice NixiesI hadn't seen the thread hiding away in the Beginners section. I have seen similar ones on evilbay from time to time and occasionally tempted.Given the instrument you really need a better 1V source than even 1PPM assuming it's own internal reference is at least that stable. Those cheap Chinese references are reasonable to 3.5 and 4.5 digit meters or as a sanity check on whatever you may build is close to the actual 1V but no more. The initial accuracy of the Maxim references and the easy trimming I would have confidence to better than 4.5 digits against another good meter but not to 6.5 digits.Nothing I have for example is up to 'recalibrating' my Agilent 34401A other than I have a pair of 34970A dataloggers with 6.5 digit multimeter cards fitted that are near the same spec. All of my references held at a static temperature give me a reasonable level of certainty as to how the 34401A is behaving over time and temperature but as it is currently out of Cal it really needs to take a trip to a lab or I need to scrape the $ together for a 3458A and keep that in Cal to keep the rest in lineWhat should be important to you is that YOU are happy you have the required level of precision, accuracy and certainty YOU need unless you go to the cost of getting the meter calibrated at a known Lab. Pick a day or conditions at a known temperature and record it preferably 20-25C. Then raise or lower just the meter if possible and see how the drift is with temperature while the reference hopefully remains at a static temperature. Also watch your connections to the meter you will get several PPM of error with a bad connection. The Russians use an oddball size under 4mmShould you build a reference YES but bear in mind what that reference will give you. The Max will get you about as good as you can get for initial accuracy without breaking the bank. To go to an LM399 or LTZ gives you more ultimate stability but a wider range of initial accuracies so if you don't trust the meter a worse result"
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 09:02:07 am",
"content": "Quote from: Rafael on January 27, 2019, 03:17:20 amIf you follow the points in that reference, you will find that most people on most forums will be friendly. A small proportion might not, but that's people for you.QuoteYou probably want to calibrate each range separately; a stable known voltage and a 7 decade Kelvin-Varley Divider is a good starting point. You will realise there is no end point in voltnuttery, only an acceptable level of dissatisfactionYou might like to do some initial experiments.For example find a battery which is reasonably stable, keeps its temperature reasonably constant, connect it to your meter, turn on the meter, and record the measured value until it becomes stable. Some meters (particularly old ones) take quite a few hours to stabilise. Keep an eye out for popcorn noise in the meter's reference, and variations with temperature.When at the uV levels, seebeck/thermocouple effects become noticeable."
},
{
"post_id": "",
"author": "iMo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 09:47:54 am",
"content": "The answer is simple: there is not such an 1V/1ppm source available in form you would expect (not talking volnuttery capable calibrators). As I can see on the pictures from your link you are already volnut-positive, so you are asking in a wrong section"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 10:08:16 am",
"content": "As you already have the same reference I jotted down some figures using my matching one this afternoon against my 34401A over a few Temps. Both meter and Reference were in the same environment and you will get an idea that the combined drift is +1ppm/C @ 10V the bulk of this based on other testing will be the Vref as the Agilent is well under 1ppm over this sort of environmental range.Interestingly the buffer used on it is not effected by loading at either 10M or 1G more than 1 least significant digit.Mainly done for me to upgrade the data for it after a years use. These cheapies are far from terrible for3.5 and 4.5 digit meters. You might even do reasonably putting a divider across one of these too just keep the values fairly high to minimize loading but still make your own as well25CNominal 25C 28C 32C old data2.5 2.49905 2.49908 2.49912 2.499055.0 5.00024 5.00027 5.00032 5.000217.5 7.49961 7.49964 7.49968 7.4995510 10.00036 10.00039 10.00045 10.00028"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 10:10:22 am",
"content": "Quote from: imo on January 27, 2019, 09:47:54 amMore than that without a base standard you have nothing to reference it to so you need to do the best you can and are happy with unlike volt nuttery. You can make all the LTZ references you like and still not know what a volt is."
},
{
"post_id": "",
"author": "Rafael",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 27, 2019, 01:04:02 pm",
"content": "Accuracy and stability really make me happy. Having an equipment and believing in your measurements fascinates me. This antique equipment, Russian, is in excellent condition (at least cosmetic) and I want to get to a point in having vintage equipment with nixie displays and precision.I've invested a few hundred dollars in parts and calibration devices.But I still do not feel safe to calibrate my other equipment! I have older nixie-based devices clamoring for calibration, such as Meratroniks, Fluke, etc ... They leave any bench happy."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 01:25:43 pm",
"content": "Not sure if this is widely known around the world but there is an adage \"A man with a watch knows what time it is. A man with two watches is never sure.\" and that is clearly why a third and a forth and a fifth.. Meter is needed. Welcome to TEA.While I am comfortable with what standards and calibration equipment I have available is more than what I need my journey down the voltnut rabbit hole is heading toward a 3458A and paying keep it in Calibration so I can start with a proper traceable voltage among others. If the budget doesn't allow it this year then my 34401A will get re calibrated by Keysight to get me a little closer to the truth and allow me to go over all of my other gear with good certainty.I have a few Nixie meters in my collection there is just something about the glow"
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 02:59:43 pm",
"content": "Quote from: beanflying on January 27, 2019, 01:42:13 amwhich is -240ppmQuote from: beanflying on January 27, 2019, 01:42:13 amThis seems to defeat the whole purpose of a precision voltage source, or have I missed something?The switch from virtually no load, to a relatively heavy load of 10M has changed the whole aspect of the design."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 27, 2019, 05:00:30 pm",
"content": "To calibrate a meter one would likely need both a stable and accurate reference. So just building a reference could result in something like 1 V with < 1 ppm/K TC , but the absolute accuracy would be poor (e.g. like 0.1% or maybe even worse).For a good absolute accuracy chances are a used Hg Cell (e.g. Weston) is probably the best chance if you don't want to pay for a used Fluke 732 or similar. Depending on the meter it may not need exactly 1 V the slightly higher voltage mercury cell may be acceptable too. It would still need a precision buffer"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2019, 12:56:59 am",
"content": "Quote from: spec on January 27, 2019, 02:59:43 pmIt depends on what you want the divider to show and to what particular DUT. What Raphael needs effectively is a transfer standard using a cost effective method. Not sure of the nixie meters input impedance but as it is a 6.5 digit meter likely to be a lot higher than 10M?My 735A Transfer Standard is sensitive to loading but it has a compensation pot available on the front panel to tweak this nominal 1V if needed. Normal procedure with this device is to Null it against a Weston Standard Cell (known voltage) or similar like I showed previously to set it's internal reference then via the internal divider network set a 1V output. Null meters in common use at the time in theory have an infinite resistance at the Null point so don't load the cell or dividers. Manual is here if anyone is interested and it goes into the theory of operation and calculations for lower impedance meters using this transfer standardhttp://literature.cdn.keysight.com/litweb/pdf/00735-90002.pdf?id=1870825To do this without a known volt source other than the 'claimed' accurate voltages on the 584K and or any other reference he may makes the 'initial accuracy' is the best guide to how close that may be and then test one against the other. So the MAX 6350 will have an initial accuracy of 5V +- 0.5mV in practice it will be better than this spec. Part of the issue is we are trying to make wine from pig swillYou will not get the 'perfect' resistors to divide up the 2.5 or 5V source to 1V so compensation will be needed be that adjusting the input voltage or providing compensation on one or both legs of the divider. The reason I suggested tweaking the Reference is the trimpot (generally terrible tempco) will be fairly unaffected by temperature variation due to it's already narrowed range. The alternate is to do something similar to the 735A circuit and minimize the value of the trimmers in the circuit.If he is to build a new reference I would use the 6350 as a start point as the +-0.5mV initial accuracy is the same for the 2.5V version which would make it twice the error."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 28, 2019, 03:32:17 am",
"content": "Quote from: beanflying on January 28, 2019, 12:56:59 amThanks for reply(I do appreciate that most approaches would require an initial adjustment to get the absolute voltage spot on.)I see, a transfer standard- that puts a whole new complexion on the design. What I see is an issue though is that relying on the input resistance/characteristics of the meter to be calibrated may wreck even the performance of a transfer standard as the characteristics of the meter input are not known (to the 1ppm level that is). Or are you proposing adjusting the transfer standard every time it is used? Perhaps that is the normal procedure.Interesting stuff about your 735A transfer standard.I wonder if a ref voltage of 1V25 would be acceptable because, if so, an LTC6655 based design could be used and no potential divider would be necessary. Admittedly the LTC6655 is 2ppm but, maybe, keep the LTC6655 at a constant temperature to fix that in terms of the overall performance of the voltage reference unit.On the other hand, if a 1V reference was essential a voltage divider for the LTC6655 could be made to have a lower output resistance and that would reduce the effect of loading delta/unknowns.It is a shame this is not a volume production job, because then we could just phone up the manufacturer, Maxim/LT/AD etc, and get them program a 1V Vref version for us.https://www.analog.com/media/en/technical-documentation/data-sheets/6655ff.pdf"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2019, 04:04:13 am",
"content": "Just to complete the sort of usage method here is what I did today.Agilent 34401A set to 10Meg Impedance.Adjust the HP 735A Transfer using the meter to 1V (actually ran out of cal range on the front panel so 0.999993)Take that know 'known' (as known as I can make it) voltage and apply it to the 10Meg inputs of the DUT in this case the 121GW.Result the 121GW is horrid and should never be trusted to read anything for reasons at least according to some .....For interest the 735A is well under 1ppm/C (done by longer term logging) and the tests were done at about 28C as per the121GW.The procedure using a homebrew solution would be fairly similar prepare the source as best you can for the test you plan for the DUT in question."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2019, 07:04:16 am",
"content": "Quote from: spec on January 28, 2019, 03:32:17 amGenerally for Cal points they are fairly specific. So Apply this then tweak that scenario is normal. So you would need the 1V.Most meters would take the form of 1V, 10V and maybe 100V and 1kV (34401a needs all of these for a full cal) depending on how it is designed to be calibrated just for DCV. The 121GW for example needs 5,50,500 & 600 for the DCV and a couple of others for the mV range for a full Cal of just the DC volt side of the meter. This is why in part you see DC Calibrators to 1000V.The thing to bear in mind is you were to use say the higher accuracy version of the LTC6655 at 1.25V then it's initial accuracy (0.025%) is 1.25 +-0.3mV so divided down the best 'known' accuracy will be higher than the MAX6350 not a deal breaker but if you don't have known volt it is an issue. A little care needs to be taken regards the long term stability figures of both devices and both will tend to settle with use to value X and then need an additional tweak but to what is the questionNow we have scared or driven off everyone to or away from Metrology for ever come on in the Rabbit Hole is large and very very deep"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2019, 07:01:54 pm",
"content": "The Mercury reference cells are just 2% higher than 1 V. So it might still work. With such an old meter this might have well been the reference of choice at that time. Even if one had to divide down to exactly 1 V, it would help starting at just 1.019 V - the divider resistors would be responsible for only 2% and thus something like 12 times less critical than in a 1.25 V to 1 V divider.An accurate 10 V reference and Hamon type divider (accurate 1:10) could be an option too."
},
{
"post_id": "",
"author": "Wolfgang",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2019, 09:35:44 pm",
"content": "Quote from: Rafael on January 26, 2019, 12:22:53 amIf you are serious there is but one choice: Make a Josephson standard. All other stuff is a crippled compromise. 1ppm is below everything you can buy from renowned companies. And dont forget to join the TEA and the voltnuttery forums."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2019, 11:02:49 pm",
"content": "Quote from: Kleinstein on January 28, 2019, 07:01:54 pmCan you still buy Mercury batteries in the EU or only from suspect sources?Building a Hamon Divider for myself too when Mr Pettis catches up a bit"
},
{
"post_id": "",
"author": "ArthurDent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 03:13:29 pm",
"content": "Here is a photo of the first of my two LTZ1000ACH 10 volt buffered references. It has been powered on and aging for months and is pretty damn stable. When in use it will only be run on battery power to avoid any possible offsets caused by any stray coupling caused by the power lines. Even with all the care I've used to construct this standard it still has to be adjusted and measured and no matter what I do it will fall short of 1 ppm.If you can get 10 volts it is simple to divide it down to 1 volt."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 04:13:26 pm",
"content": "Quote from: beanflying on January 28, 2019, 11:02:49 pmA mercury battery (like those old coin cells) would not help that much, they are more like 1.45 V and relatively high TC. There is essentially no way to get them anymore. AFAIK they are not manufactured anymore and thus would be old and likely bad by now. The point are used mercury reference cells. These are larger and last longer and still sometimes come up on ebay or similar. However they are difficult to transport - not all of them are like transport per parcel and the transport may not be allowed anyway, because of the mercury and acid inside. The cell may still need an extra high impedance buffer and temperature compensation or stabilization.For a Hamon divider one does not need that super stable resistors. The idea usually is to first adjust the resistors chains to be equal and than do the extra connections to go from 3:3 to 1/3:3 resistor ratio. So it needs an extra adjustment step before use. The final accuracy is like the square of the resistor ratio accuracy. So starting with 0.1 % resistors is enough to get to the ppm range. It still needs care to avoid errors from self heating, thermal EMF and leakage."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 04:16:19 pm",
"content": "Doesn't a Harmon divider just provide an accurate, and stable potential divider? If that is the case, doesn't that still leave the inaccuracies cause by the 10M Ohm load of the meter under test?Doesn't the same problem of loading apply to all reference cells too? Presumably, they have a significant output resistance (in terms of 1ppm)."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 04:32:04 pm",
"content": "Can I ask a question of the experts in this field: When you are checking the precision of an instrument, what is the shortest time that the instrument could be connected to the reference source? I have a reason for asking."
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 04:37:55 pm",
"content": "A mercury reference cell would need a butter for a 10 M input impedance meter. This usually also applies to a Hamon divider, unless rather low impedance, which would call for self heating problems. However 6 Digit DMMs often have more than 10 M input impedance in the low voltage ranges."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 05:36:00 pm",
"content": "Quote from: spec on January 29, 2019, 04:32:04 pmI would suggest \"until the reading is stable and repeatable\", where you have to supply the two obvious definitions.Are you thinking of a mechanical multimeter and a Weston standard cell?"
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 07:27:53 pm",
"content": "Quote from: tggzzz on January 29, 2019, 05:36:00 pmMy thought was to use a capacitor to lower the effective output impedance of a precision voltage divider but, in view of your and K's, remarks it is clear that a fair amount of time would be required to do the calibration so that idea goes down the tubes as only a film capacitor could be used. A supercap, which could allow sufficient time, would be too leaky, I think"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 29, 2019, 11:46:19 pm",
"content": "This can just go around in circles until you fall deep into the rabbit hole. When you go beyond 4 1/2 digits of resolution each extra one is 10 times the work to do it right. Until you have a traceable stable known reference to work from you will never truly know what you are reading in particular at 6 digits and greater.So at some point failing that YOU need to create YOUR Volt preferably as close as you can to the 'true' value.For a basic home lab this can be as simple as pick your best meter and what it says rules the others. Worst option so buy/make a Vref.Buy one of the AD584 based references making sure it has the 'known' voltages recorded on it (most seem not to have this currently). Works well offers a range of outputs and is stable against 10M and GOhm meters. Suffers some initial drift from stated figures over time and drifts in the order of 1PPM/C. Should handle a divider to 1V and maintain ok stability and accuracy of its voltage with a small load.Standard Cells of various sorts. SeeRocking Horse PooRequires a GOhm meter or preferably a Null Meter and several cells. Not practical but a stable over time now curio and a sanity check device for me - if you can buy one they are Cool. NIST is back from being shutdownhttps://www.nist.gov/sites/default/files/documents/calibrations/mn84.pdfLM399 and LTX1000 based devices are POINTLESS unless you have a 'known' accurate standard or meter to set them with their initial accuracy varies widely. They will only be as 'accurate' as the device YOU measure them with but generally they are more stable than other References due to Temp but can take weeks to years to settle. They are a can of worms in the Rabbit Hole with you in free fall but always just out of reachRoll your own using the best initial accuracy Reference you can buy sensibly back to the Max series (Best Initial Accuracy) again unless someone else knows of a $10USD one that is better? I have Two in aluminum boxes running from LiPo batteries tweaked to give me an accurate 10V I am happy with for outside use. I do also own a Fluke 515A portable Calibrator which is great to 4.5 digits meters but not so good for 6.5 as it drifts more than the Max based References.Use your best 'known' Reference to 'Null' out a separate supply with more grunt if you need it to avoid loading issues and test it's performance as you load it to see if it remains 'stable' as you load it. Feed that into a Hamon or whatever divider or op amp you like and test away being happy in the knowledge it is YOUR Volt"
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 01:08:40 am",
"content": "Quote from: spec on January 29, 2019, 07:27:53 pmCapacitors are crap components compared with resistors. Leakage, tempcos, non-linear voltage dependence, dielectric absorbtion, and more."
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 01:14:42 am",
"content": "Quote from: beanflying on January 29, 2019, 11:46:19 pmGetting a meter to agree with a voltage source is easy: just turn the knob.Getting one meter to agree with another meter is a little more difficult: open one up and recalibrate it.Getting one of your meters to agree with other people's meters is easy: just empty your wallet.QuoteCells also have another advantage: no popcorn noise. That enables you to infer the noise in a meter's reference."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 04:04:35 am",
"content": "Quote from: tggzzz on January 30, 2019, 01:08:40 amOh yes I do know that, but there are capacitors and capacitors. Still overall you are obviously right. It was just a thought.UPDATE: just noticed that the LTZ1000 does use a capacitor internally."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 04:15:33 am",
"content": "Quote from: beanflying on January 29, 2019, 11:46:19 pmAre the electronics in the aluminum boxes in a controlled temperature?"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 04:32:36 am",
"content": "When not in outside use yes. I have a hacked wine fridge at 25C. and 34970A loggers with DMM cards fitted. Still a WIP and it also has two newish LTZ1000 Refs and the bits for two more coming.If it wasn't out of interest there is nothing I do that requires more than 4.5 digits but having that known 6.5 digit and references gives me very good confidence at that 4.5 has very good confidence. The consideration to jump to 8.5 is a total indulgence and I am still weighing up that or a modern 1/2 rack 7.5 digit option. Either way it would be kept in Current Cal."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 04:49:19 am",
"content": "CROSSED POSTSQuote from: beanflying on January 29, 2019, 11:46:19 pmIsn't,'They will only be as 'accurate' as the device YOU measure them with'true of any Vref that you make?Both the LTZ1000 and the LM399 are oven controlled. The LTX1000 is top of the chip heap, so why not use it. OK you may not realise it's full potential, but so what. Is it because of the $50 price tag? At a lower spec (0.5ppm) and price ($12), the same goes for the LM399, or is it because the LM399 is a shunt type, which complicates the design, compared to a series type?It would appear that the basic vref of the LM399 cant be that good if it only achieves 0.5ppm/degC performance with oven control. My thinking is that there may be big gains in performance by oven controlling one of the au natural chips we discussed, which as you say, also have an initial absolute accuracy around two orders better than the LM399.https://www.analog.com/media/en/technical-documentation/data-sheets/199399fc.pdfhttps://www.analog.com/media/en/technical-documentation/data-sheets/LTZ1000.pdf"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 05:00:02 am",
"content": "In the case of Ref's like the LM and LTZ their initial accuracy varies heaps so without a good meter they are no good for a walkup 'accurate' home built reference. The Max6350 runs rings around them for initial 'accuracy'. So if you have no 'known' source don't build one IMO there is simply nothing to be gained unless you already have a very good calibrated meter which in Raphael's case he gives no indication of.LM399 6.75 - 7.3 V initial 'accuracy'LTZ1000ACH 7.0 - 7.5 V initial 'accuracy'MAX 6350 4.999 - 5.001 V initial 'accuracy' (0.02%)"
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 05:16:59 am",
"content": "Quote from: beanflying on January 30, 2019, 05:00:02 amAgree. But at one stage you were suggesting that the Vref be used as as a transfer standard, which implies another precision reference- or have I got that wrong.To put a stake in the ground can I suggest that we consider two approachesTransfer standard (with high output R and adjustment)Stand-alone absolute Vref, with low output R (suitable for a load of 10M or higher) and initial calibration (if required) by resistor AOT.I have an interest in two above."
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 05:57:16 am",
"content": "With no calibrated gear it becomes a chicken and egg type of thing you still need an 'Accurate' Reference to make that Transfer Standard. So your choices are buy or make the best one you can.Vref best options without going broke.1 - Buy an AD-584 with measurements attached. With no measurements it is no better than your current best meter for Accuracy.2 - Build a MAX6350 based reference and make it YOUR volt. It wil be better than just about any 4.5 digit meter I am aware of for initial accuracy?3 - There is 399 Refs in the for sale section at present for not to many $$ but I am not sure of what there long term aging or stability is as I haven't looked at the project other than a glance in the for sale section? Personally I would stay away unless you already own a meter capable of tracking and looking at its drift (6.5 digits)4 - DMM check or similar other devices are also available online.How you get to the various voltage points to transfer YOUR Volt from there is a topic in itself and really to large for here and outside basic dividers and not Beginner material in particular. Depending on the meter you want to Cal as I put a few posts back you need to hit a huge number of different points even for a couple of meters. This is why I own a couple of Calibrators both AC and DC to 1000V+ but they are not sensible for most apart from their boat anchor dimensions as per the photo below.One other possible option is you go down the path Ian Johnson has with his LM399 based Referencehttp://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-v2-detailusing a good quality DAC/micro on the reference but this is way out of Beginner level and will cost real money.Back shelf is how to go 'part' of the way into the rabbit hole 7.5 digit Advantest on the top shelf, HP735A, Fluke Null meter, Fluke Portable Calibrator, Bottom row HP 740B working but mid renovation 1000V DC Calibrator/Null meter and Valhalla 1200V AC Calibrator. Won't mention my 'slight' time nut addiction either. Plus other assorted 'stuff'. No I don't feel I have a problem because TEA assures me I am 'normal'Yes I am showing off the toys a touch"
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 08:17:16 am",
"content": "Quote from: spec on January 30, 2019, 04:04:35 amAt voltnut level there are no individual components, only black boxes with lots of hidden and poorly specified internal componentsPeople spend careers trying to minimise and work around that.Silicon capacitors are no different in that respect. BTW, youcanget discrete silicon capacitors in the range 0.3pF to 3.3uF, but watch the availability, MOQ and pricehttps://www.digikey.co.uk/products/en/capacitors/silicon-capacitors/68?k=silicon%20capacitor"
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 11:20:51 am",
"content": "Quote from: beanflying on January 30, 2019, 05:57:16 amThank you for such a comprehensive summary.In view of what you and tggzzz say, it might be folly, but I would like to have a go at designing a stand-alone, low-impedance output Vef. So if I get around to posting a schematic, your comments would be appreciated.I have done a couple of outline schematics which, in theory, look promising, but I lack the specialist knowledge and experience that this field requires. My only qualifications are having read the threads on EEV and elsewhere on the net."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 11:25:30 am",
"content": "Quote from: beanflying on January 30, 2019, 05:57:16 amNice"
},
{
"post_id": "",
"author": "tggzzz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 11:31:40 am",
"content": "Quote from: spec on January 30, 2019, 11:20:51 amFolly? No. You'll have fun and learn things. But personally I wouldn't tweak anything based on its output - first attempts are rarely perfect.You should understand what's behind the specs for professional high quality meters, especially those related to the drift over time.You might like to consider what will/won't happen if you short-circuit your low impedance output."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 11:34:16 am",
"content": "Quote from: beanflying on January 30, 2019, 05:57:16 amYou have mentioned the AD584 a couple of times, but according to the datasheet, it is no big shakes (15ppm) compared to the other chips. So what is the story with the AD584?https://www.analog.com/media/en/technical-documentation/data-sheets/ad584.pdf"
},
{
"post_id": "",
"author": "beanflying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 11:42:46 am",
"content": "The Acrylic enclosed references uses the AD584KH. It is specced at 15PPM Maximum there is no typical or minimum PPM/C which is a bit strange. Based on what I measured the other warmish day I was getting 1PPM from mine soInterestingly the Initial Accuracy is only Maximum rated tooDo a Search for KKMoon or AD584KH reference you should get plenty of hits here on others that have tested it."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 11:48:12 am",
"content": "Quote from: tggzzz on January 30, 2019, 11:31:40 amYes, well put. I don't actually need to calibrate anything, at the moment. A half-decent voltage reference would just be an interest.Quote from: tggzzz on January 30, 2019, 11:31:40 amOh yes- got that right from the off. I have done quite a bit of precision work, but never designed/built an ultra precision Vref. I spent a year doing the development cal of a precision analog computer at one time, and had access to the highest precision voltage and resistance references, via the company- cost was not an issue.Quote from: tggzzz on January 30, 2019, 11:31:40 amNot much I don't think. But it may introduce a thermal shock to the V Ref Unit, which could take a day or so to recover from.What does concern me is the secondary effects, like galvanic voltage of metals and solder joints- that kind of thing."
},
{
"post_id": "",
"author": "spec",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 30, 2019, 12:21:55 pm",
"content": "Perhaps I could outline the V Ref Unit (VRU) design I have been looking at, in the background, recently:Ref Voltage: any from 0V to 10VTarget Absolute Accuracy (max): TBDTarget Tempco (max): 1ppm/degCCalibration: none, or resistor AOT depending on degree of precision required.Material Cost (max): $100USDevelopment Effort (max): Infinite man hoursDimensions (max): Width: 300mm, Depth: 250mm, Height: 150mmWeight (max): 1.5 kgCase: DIY. Material: TBD, but probably a mixture of plastics and aluminum. The case would have at least four thermally isolated compartments. The first compartment would house the electronics that are primarily responsible for voltage precision. The second compartment would house the components that have a secondary effect on voltage precision, the third compartment would house the precision linear power supplies. The third compartment would have an efficient heatsink. The fourth compartment would house the batteries.Power Source: mains and battery. Mains components housed in wall-wart or similar.Power Consumption (max): 100WPower Rails: precision low-noise using specialist linear PSU chipsPrimary Voltage Ref: one of the chips that we have discussedBuffer to Provide 'zero' Ohm Output Z: super precision opamp (I seem to have found one)Thermal Control: Possibly oven controlled primary voltage ref. All relevant circuitry in DIY ovens (simple to do, but the practical side would take some sorting)The VRU would probably require a six-month burn-in period to reach full performance, but would be usable after a couple of days for less precise work.Obviously, the VRU would be powered permanently, either from the mains or battery."
},
{
"post_id": "",
"author": "Alex Nikitin",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 31, 2019, 02:41:06 pm",
"content": "Quote from: spec on January 30, 2019, 12:21:55 pmHave a look at this voltage source, manufactured by a forum member here:http://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-v2-detailCheersAlex"
}
] |
2025-10-17T18:17:27.404029
| 64
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1v-zener-diode-doesn_t-even-break-down-at-5v!/
|
1V zener diode doesn't even break down at 5V! - Page 1
|
[
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 09, 2013, 07:07:23 pm",
"content": "I ordered a 1V zener diode from Conrad but it doesn't work for some reason. I'm powering my project using 5V but when I put the zener in backwards no current will flow even when I don't use any resistors at all! When I put it in forward bias it just drops 600-700mV...Datasheet:http://www.produktinfo.conrad.com/datenblaetter/175000-199999/180505-da-01-de-Zenerdiode_ZPY_1_V.pdfAm I doing something wrong here?Thanks in advance,Nick"
},
{
"post_id": "",
"author": "Bored@Work",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 07:26:05 pm",
"content": "You don't get zener diodes that low. What you have is a normal diode intended to operate in forward direction, sold as a \"zener diode\"."
},
{
"post_id": "",
"author": "olsenn",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 07:28:38 pm",
"content": "I'm guessing it's a 1 Watt rated zener diode and 1V is just a typo for 1W"
},
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 09, 2013, 07:36:36 pm",
"content": "Well this is odd I tested all 5 of the 'zener' diodes I ordered, but one of them actually had a break down voltage of 900mV! This is kinda odd. If there are no zener diodes rated for 1V then conrad is just being naughty because they literally stated it had a 1V breakdown..."
},
{
"post_id": "",
"author": "olsenn",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 07:39:21 pm",
"content": "I'm assuming you're measuring the reverse (break-down) voltage and not the forward voltage drop? Just checking."
},
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 09, 2013, 07:42:42 pm",
"content": "Yes, I'm testing the reverse breakdown voltage. I guess this wasn't the best order I did on conrad. Do you guys know if it's a good idea to get a decent voltage reference by just forward biasing the diode?"
},
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 09, 2013, 07:46:02 pm",
"content": "Just to clarify, this is literally what you see when you browse the zener diodes on conrad..."
},
{
"post_id": "",
"author": "Bored@Work",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 07:47:50 pm",
"content": "Quote from: vortexnl on January 09, 2013, 07:42:42 pmThey are meant to be operated in forward direction, and will typically exebit the behavior as specified in the data sheet. If that specified behavior matches your definition of \"decent\" the answer is yes."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 07:48:11 pm",
"content": "The \"1V\" is a silicon diode run in forward conduction. Tip is the voltage drop is the same as a lightly doped diode. The one breaking at a low reverse voltage is probably a faulty one that has contaminants on the die causing this. Not found in test as they are not tested at any reverse voltage at all."
},
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 09, 2013, 07:49:13 pm",
"content": "Quote from: Bored@Work on January 09, 2013, 07:47:50 pmOh I'm sorry, what I meant to say was... Is it possible to use a regular diode as a voltage reference by just forward-biasing it..."
},
{
"post_id": "",
"author": "jeroen74",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 07:57:26 pm",
"content": "The German site of Conrad has a datasheet in German and that states the 1V version is just a plain diode.http://www.produktinfo.conrad.com/datenblaetter/175000-199999/180505-da-01-de-Zenerdiode_ZPY_1_V.pdf"
},
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 09, 2013, 08:02:07 pm",
"content": "Quote from: jeroen74 on January 09, 2013, 07:57:26 pmToo bad my german isn't that great! I guess I'll have to read the datasheet more carefully next time instead of relying on conrad's data.Many thanks to everyone that responded, my next zener purchase won't be a fail"
},
{
"post_id": "",
"author": "Bored@Work",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 08:03:42 pm",
"content": "Quote from: vortexnl on January 09, 2013, 07:49:13 pmSure, done all the time and there is no magic behind it. Same thing with LEDs. If the resulting regulator is \"decent\" depends on the requirements for that regulator."
},
{
"post_id": "",
"author": "PA0PBZ",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 08:21:16 pm",
"content": "Quote from: vortexnl on January 09, 2013, 08:02:07 pmIt is the same datasheet you linked to in your first post. On the first page there is a footnote (3) behind the ZPY 1. If you look at the footnote it says: \"Die ZPY 1 ist eine in Durchlassrichtung betriebene Silizium-Diode\". That should not be too difficult to understand for a Dutch speaking person\"(\"De ZPY 1 is een in doorlaatrichting gebruikte Silicium Diode\")"
},
{
"post_id": "",
"author": "jeroen74",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 09, 2013, 08:29:04 pm",
"content": "QuoteYou think? I find German quite difficult to understand while both languages probably sound very similar to people not speaking either one of them.This particular sentence wasn't too difficult though"
},
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 09, 2013, 11:19:05 pm",
"content": "Unfortunately german isn't really my thing, I only like to learn the naughty words"
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 10, 2013, 05:35:02 am",
"content": "We probably have left the US and UK, along with the Australian readers wondering what we were discussing........"
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2013, 06:02:15 pm",
"content": "If you want a 1V reference you can use something like a TL431 this is a 2,5V Vref and you can use a voltage divider to get 1V. They can not deliver power. In that case you need some more electronics behind it ( like an opamp and power transistor)Also do some reading about the difference between diodes and zeners. It is in every basic electronics book."
},
{
"post_id": "",
"author": "UPI",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 11, 2013, 06:32:44 pm",
"content": "Quote from: PA4TIM on January 11, 2013, 06:02:15 pmTL431 Calculator:http://xtronic.org/download/regulator-designer-voltage-current-shunt-adjustable/Maybe something like the attached image. You would use a divider to get it down to 1V as PA4TIM suggested."
},
{
"post_id": "",
"author": "Bored@Work",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2013, 07:14:32 pm",
"content": "The TL431 can't be easily configured for anything below it's internal 2.5 V reference."
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2013, 07:51:49 pm",
"content": "Hmm, maybe if you are at one time bored at work you can read the application notes, datasheet and a book bout opamps( just kidding)I made several at 1V. But it depends wat you find easy"
},
{
"post_id": "",
"author": "Bored@Work",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2013, 08:30:03 pm",
"content": "Pah. Your four references are all configured for 2.5 V and then you throw how many, 20, 30 more parts at it? All that for what started as a simple diode, and while thishttp://www.digikey.com/product-detail/en/ADR510ARTZ-REEL7/ADR510ARTZ-REEL7CT-ND/820440can be had starting at $1.75."
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2013, 08:50:49 pm",
"content": "Yeah, indeed, very complex, two opamps and for a dollar worth of resistors. You are right, very heavy analog voodoo stuff. Is the modern EE afraid of everything more then one part ( most times named atmel or pic) ? They make the most simple things with an overload of digital stuff but two opamps and some resistors is heavy. I'm afraid f the future of anlog design. It takes me more time to type this than to build it.But i'm just ranting ;-)All depends on what the topic starter wants to do. If he just wants 1V and not much accuracy he can use two resistors. If he wants to make a moderate accurate Vref he can use one TL and one sinple opamp and less then 10 resistors. If he wants to make 1.000,000V he just has to forget t for nowAnd there are many more options"
},
{
"post_id": "",
"author": "vortexnl",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "January 12, 2013, 11:02:11 am",
"content": "Unfortunately I live in the Netherlands and I don't have that many resources when it comes to IC's and stuff. (except ebay and stuff like that)That is why I usually like to build everything from analog parts because I don't feel like waiting 2 weeks for an IC to arrive."
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2013, 11:33:22 am",
"content": "Strange, i do not have that problem and I live in the same country.Besides Conrad there are dozens of webshobs like Kent electronics,Or look here :http://www.circuitsonline.net/shops/1/name/0?type=&name=&city=®ion=&country=nlBut we still do not know what you want to use a zener diode for. Where you need 1V for and how accurate should this be. Maybe there is an other way to solve this."
},
{
"post_id": "",
"author": "Bored@Work",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2013, 04:00:11 pm",
"content": "Quote from: PA4TIM on January 11, 2013, 08:50:49 pmNo, the modern EE is cost, energy, effort and space conscious and doesn't throw 30 parts on a board if a single 1.000V, three pin SOT-23-3 reference is easily available.Quote from: vortexnl on January 12, 2013, 11:02:11 amIn this threadhttp://mightyohm.com/blog/2010/11/where-do-you-shop-for-electronics/someone mentioned RS, Farnell (aka Element14) and dickbestfor the Netherlands. And someone points to a list of 120 mail-oeder shops in your neighbor country Germanyhttp://www.mikrocontroller.net/articles/Elektronikversender"
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 12, 2013, 04:50:10 pm",
"content": "Again, we first have to know what the TS needs.Maybe 1.0V is good enough ( because of his limmited knowlegde I do not think he want up to 1 uV precsion ;-) so probably your suggestion will be a usefull one)The ADR510 is 1.000V plus/min 3.5 mV and if he is a beginner the sot23-3 can be a problem."
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2013, 11:18:20 am",
"content": "I never tried but I just read a IR led is a good 1.1V zener."
},
{
"post_id": "",
"author": "ConKbot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2013, 12:20:11 pm",
"content": "Quote from: PA4TIM on January 12, 2013, 04:50:10 pmOh cmon nowyou can put SOT-23-3 on a 0.1\" pad-per-hole perfboard. Its not the prettiest thing, but at least you dont need to buy an adaptor."
},
{
"post_id": "",
"author": "PA4TIM",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2013, 12:31:47 pm",
"content": "Hey, i solder 0603 by hand, but i have good eyes and a good solderstation. There are biginners with cheap bad solder, using S-39 and a 50W plumbers iron"
}
] |
2025-10-17T20:27:01.131423
| 30
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1w-leds-bulbs-circuit-equivalent-to-60-70w-incandescent-bulb-brightness/
|
1W LEDs bulbs circuit equivalent to 60-70W Incandescent bulb brightness - Page 1
|
[
{
"post_id": "",
"author": "Shivram10",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 28, 2015, 07:23:47 pm",
"content": "Hello everyone,I have a small onetime product photography project which is under a tight budget for eCommerce site for a friend, I have made a lightbox somewhat like this(image for reference only),now I wanted to build 2 softbox lights with 2 Nos. 60-70W and 1 Nos. 100W equivalent incandescent bulb brightness.(image for reference only)I have around 50-60 1W leds with heatsink, I also have aluminum pieces which can hold 18-20 1W LED. I wanted to use them for the project, its a one time project for few days so buying a professional setup is no use for me. I have searched online for schematic of LED Bulb I couldn't find any which are above 6W.If anyone can provide me a schematic for the above mentioned circuit it will be a great help.Regards,ShivramPS : - I am an amateur electronic hobbyist and I have limited knowledge of formulas for calculation of the input and output voltage, I can assemble a schematic though and I have most of the parts like Resistors, capacitors, LM317 Voltage Regulator etc lying around so I want to use them. I want to power directly via 220v AC mains if possible."
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 28, 2015, 07:34:42 pm",
"content": "Quick note. I would avoid any PWM dimmer circuits. A LED is quite fast and the pulsing of LED would give unpredictable results when mixed with shutter speeds."
},
{
"post_id": "",
"author": "Shivram10",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 28, 2015, 07:38:38 pm",
"content": "Quote from: Seekonk on October 28, 2015, 07:34:42 pmThanks for your reply,I don't want any dimmer circuit. I want constant bright light."
},
{
"post_id": "",
"author": "Nerull",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 28, 2015, 11:52:30 pm",
"content": "Why not just use off-the-shelf led bulbs in some small lamps? They're already ready to run off mains and available pretty much anywhere."
},
{
"post_id": "",
"author": "BravoV",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 28, 2015, 11:56:18 pm",
"content": "Quote from: Nerull on October 28, 2015, 11:52:30 pmThe op is from India, I'm guessing mains led bulb is still not popular there, or maybe they are still relatively expensive,"
},
{
"post_id": "",
"author": "ivan747",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 12:26:58 am",
"content": "Can't you rent the equipment?"
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 12:29:59 am",
"content": "Incandescent bulbs will give good colour rendition if you apply the appropriate colour correction in camera or in software as they have a continuous light spectrum with no gaps in it.LEDs may not give such good results (it will depend on the colour rendition index of the LED).So if you have access to incandescent lamps it may be advantageous to use them? If you have the camera on a tripod you can use longer shutter speeds to compensate for lower light intensity too."
},
{
"post_id": "",
"author": "nbritton",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 12:31:10 am",
"content": "The problem that you're not thinking about is the CRI (Color Rendering Index) of those 1W LEDs will be extremely poor because they don't have the right phosphor for your application. They will make very poor quality studio lights, do not use them. You would be better off using a High CRI general purpose light bulb like the the Cree TW.What you really want is this:http://store.yujiintl.com/collections/frontpage/products/bc-series-cob-400l?variant=1424975617"
},
{
"post_id": "",
"author": "nbritton",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 01:02:45 am",
"content": "Quote from: Shivram10 on October 28, 2015, 07:23:47 pmThen go buy some LED light bulbs with easy open packaging at Home Depot and return them after your done, or re-use them in your home. Most bulbs are rated for 25,000 hours, but only come with a 3 year warranty (what's up with that?), so I don't think anyone will truly care if a few hours of their life gets used up.Again, I recommend a high CRI bulb but you also need to make sure the bulb has a high R9 value, these are hard to find in the stores. You can do an advanced search on lightingfacts.com to find the right bulb, but the easiest thing for me to tell you is to buy the Cree TW series bulbs. In fact, most any old incandescent bulb will give you better color rendering then a LED, so just go get some 50 cent incandescent bulbs. Although, with incandescents then you have to worry about the 2700K color temperature, and I don't think the Cree TW bulbs come in 5000K. Ugh, why do light bulbs have to be so complicated.http://www.lightingfacts.com/Productshttp://www.lightingfacts.com/cahttps://www.energystar.gov/productfinder/product/certified-light-bulbs/resultshttp://creebulb.com/products/standard-a-type/60-watt-replacement-tw-series-soft-white-led-bulbEdit: Ok I thought about what you should do and here is what I would do to get the color rendering and color temperature right for your budget lightbox. In the 60W lightbox I would use one regular 40W 2700K incandescent and one 40W 5000K+ LED, this should yield a high CRI / R9 light source with a neutral white 4000K color temperature. In the 100W lightbox I would use one regular 60W 2700K incandescent and one 60W 5000K+ LED. Then connect these to a standard dimmer switch so that you can adjust the lumens based on whatever your light meter needs."
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 29, 2015, 02:45:37 am",
"content": "12volt 50watt halogen bulbs are cheap and render nicely. Power 2 with an old PC supply (4 or 5 if you soft start them to deal with the cold filament current). Keep them away from the cardboard... Edit: Use your LED's for something else, a light box isn't likely to be on for hours. Since tungsten filament response is quite slow, you could try PWM dimming."
},
{
"post_id": "",
"author": "Shivram10",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 29, 2015, 12:05:32 pm",
"content": "Quote from: Nerull on October 28, 2015, 11:52:30 pmLED bulbs which are available in my area but are less than 10W and above 10W they have to get on order basis as they are expensive here.Quote from: AcHmed99 on October 29, 2015, 12:08:15 amThanks for the info, will look into that problem, I may as well use CFL bulbs as I have few in my home.Quote from: ivan747 on October 29, 2015, 12:26:58 amNo, renting is not possible.Quote from: IanB on October 29, 2015, 12:29:59 amI didn't go for incandescent bulbs because of heat issue.Quote from: nbritton on October 29, 2015, 12:31:10 amThese are good option but they will be expensive and getting where I live in India will time consuming and also as I said earlier its a onetime project so after that the LED lights will be useless to me after the project.Quote from: nbritton on October 29, 2015, 01:02:45 amI'm from India there is no Home Depot here. Thank you for the reference website lightingfacts.com, I will look into that.Quote from: Cliff Matthews on October 29, 2015, 02:45:37 am@Cliff Matthews, Thanks for the idea, I will go and inquire at my local shops for halogen bulbs."
},
{
"post_id": "",
"author": "hayatepilot",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 01:19:28 pm",
"content": "Quote from: Shivram10 on October 29, 2015, 12:05:32 pmIsn't a 10W LED bulb equivalent to a 60-70W incandescent bulb?Wouldn't that be exactly what you need?Greetings"
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 29, 2015, 01:36:31 pm",
"content": "It's a light box, so CRI and cost is are priorities. LED's with high CRI are very costly and not easily available."
},
{
"post_id": "",
"author": "IanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 02:54:19 pm",
"content": "Quote from: Shivram10 on October 29, 2015, 12:05:32 pmWhen comparing lamps for equivalent brightness you should look at the lumens not the watts. A 10 watt LED is very bright."
},
{
"post_id": "",
"author": "hayatepilot",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 03:00:17 pm",
"content": "Quote from: Cliff Matthews on October 29, 2015, 01:36:31 pmhttp://creebulb.com/Content/downloads/product_info/40w60w_tw_product_info.pdfCree 60W replacement TW Series. 93CRI, about as high as LEDs go.10 bucks on amazon....http://www.amazon.com/Cree-Equivalent-White-Series-Dimmable/dp/B00H27TDSYSo at there are reasonably priced High CRI LED bulbs available. If one can get those in india, I don't know.Greetings"
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 29, 2015, 04:01:56 pm",
"content": "I used to get a blister pack of two 50w halogen's for a dollar. Now the successful Indian guy at the local dollar store wants $1.50 (likely more now, since I haven't bought any in a few months).BTW, 2 to 4 of these are great to quick test a PC power supply since they fit snug down beside the pins of a molex connector across black-red and black-yellow for around 65-watts of load."
},
{
"post_id": "",
"author": "nbritton",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 29, 2015, 09:23:10 pm",
"content": "LED bulbs have higher lumens per watt, so a 10 watt LED bulb is equivalent to a 60 watt incandescent. Do the product boxes there in India not show their equivalency rating?I've found you can get better color rendering if you mix 2700K and 5000K bulbs together. I do this in my bathroom, I have six fixtures so I use three 2700K LEDs and three 5000K LEDs with alternating spacing. It looks odd but it produces good quality light."
}
] |
2025-10-17T19:31:32.693765
| 17
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1w-resistor-in-a-0-25w-resistor-footprint-how/
|
1w resistor in a 0.25w resistor footprint. How? - Page 1
|
[
{
"post_id": "",
"author": "bobbydazzler",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 08, 2021, 02:01:47 pm",
"content": "I bought these resistors the other week because I needed some to just drop some voltage for a voltage regulator. I bought them based on appearance and their 1w rating(I think they look nice). Just curious about how they're capable of 1w in such a small package?They're 5% metal film resistors so are similar construction as \"normal\" 0.25w metal film resistors yet still fit in the same footprint, I have them pictured next to a \"normal\" 0.25w metal film resistor as well as a 2w metal oxide resistor(which is huge in comparison). I've stress tested them at 0.9w each soldered nearly next to each other and they ran fine, didn't melt the solder or anything so they probably were running close to their 150c max temperature."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 08, 2021, 02:58:43 pm",
"content": "It would make way more sense to increase the heatsink of the regulator on your board.Even something as simple as a bunch of solid copper wires cut from an ethernet cable soldered to the pad will increase the dissipation area ...center a bunch of wires over the pad, solder them to it, then bend both ends of the wires and spread them a bit so they look like tiny antennas dissipating the heat.A small sheet of aluminum from a can also works, but you need to use liquid flux to add solder to the foil otherwise solder won't beat the oxidation on the can... a copper coin also works reasonably well as an improvised heatsink.Regular diodes also drop voltage and they're cheap... each 1n4001 drops around 0.8v"
},
{
"post_id": "",
"author": "bobbydazzler",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "April 08, 2021, 03:27:32 pm",
"content": "My post is about the small, high wattage resistors.For a heatsink on the voltage regulator I'm limited by wanting to make the pcb as small as possible so no heatsink, though I do have a bit of 26 awg single strand copper wire soldered to the metal tab of the regulator and running the length of the backside of the pcb."
},
{
"post_id": "",
"author": "Gyro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 08, 2021, 03:36:47 pm",
"content": "Quote from: bobbydazzler on April 08, 2021, 03:27:32 pmQuite simple. They get hotter, you never get something for nothing. Their construction is such that they can sustain a higher surface temperature than bog standard metal film and carbon film ones. Usually they have a heat resisting cement covering rather than 'lacquer.Your construction needs to be able to cope with the higher operating temperature, stand-offs and spacing of sensitive parts from the (more radiant) heat source.P.S. Looking at your second photo, you'll notice that their surface area is significantly larger than that 0.25W metal film too - they just have the same useable pitch."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 08, 2021, 04:23:34 pm",
"content": "You also need to space them off the board a little, at least the body diameter, and preferably the same again for nearby parts, as they need the extra volume to cool. You can also ensure they are vertical, or at least able to convect air around them, as they will be the hottest point on the board. Long term they will turn that SRBP board black under them. As to the regulator simply take a small piece of copper strip and solder to the tab, then allow 2mm space and fold down the length of the regulator to increase dissipation. Even 2 tabs along the side will help a lot, just increase surface area. Yes burning off heat with a resistor is better, as running the silicon cooler helps a lot."
}
] |
2025-10-17T17:30:15.751887
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/1x-probe-acts-weird-(needs-compensation)/
|
1X probe acts weird (needs compensation?) - Page 1
|
[
{
"post_id": "",
"author": "beowulfenator",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 07, 2018, 08:30:59 pm",
"content": "Hi!I got my hands on a 1X probe (the manual says \"Elditest GE1502\") and hooked it up to Tektronix TAS 485. This is what I get when I probe the \"probe comp\" input.My 10X probes (HP 10071A) work fine, and I can adjust them to make the waveform square. But this probe (and a piece of any wire for that matter) produces this skewed waveform. Am I doing something wrong here?"
},
{
"post_id": "",
"author": "ArthurDent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 07, 2018, 08:52:59 pm",
"content": "Check what the input specs are on the two scopes. I noticed that different scopes have different capacitance loading on the probes that would cause the problem. You probably can't adjust a 1X probe to work without changing the coax length or perhaps a low value resistor that may be in series with different 1X probes.The Tek may be 1Mohm/20Pf"
},
{
"post_id": "",
"author": "beowulfenator",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 07, 2018, 09:08:22 pm",
"content": "The scope is indeed 1MOhm/20pF. According to the datasheet, the probe's input impedance is 65 pF. But then there are two issues: first, a short piece of wire gives the same picture and second, the P6101B probe that is mentioned in the scope's manual as compatible has input impedance of 1MOhm/100pF."
},
{
"post_id": "",
"author": "ArthurDent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 07, 2018, 09:41:11 pm",
"content": "Dave has a good explanation of what your 1X scope probe problem is. Watch especially from minute 18 onward which will describe the difference you are seeing between the 10X probe designed to work with your scope and some other 1X probe not designed to match your scope."
},
{
"post_id": "",
"author": "beowulfenator",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 08, 2018, 08:24:35 am",
"content": "Oh, I've seen that video before. I've just watched it again, and he describes a switchable 1X-10X probe that's optimized for 10X and works poorly at 1X. I've measured DC resistance of my probe, it's roughly 180 Ohm. There should be no attenuation at 1 MHz."
},
{
"post_id": "",
"author": "ArthurDent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 08, 2018, 12:27:42 pm",
"content": "I've told you what the problem is, Dave's video clearly explains what the problem is, and you can see the problem on the scope in front of you. Eventually it will become clear."
},
{
"post_id": "",
"author": "StillTrying",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 08, 2018, 01:56:37 pm",
"content": "According to my logic, it can't be anything to do with the probes or compensation, it must be a faulty 1V/Div range.Does CH2-CH4 do the same, view the 1kHz at X1, and X10 at the same time, a bit wire will do for the X1 connection, to check it's not the 1kHz itself."
},
{
"post_id": "",
"author": "beowulfenator",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 13, 2018, 05:32:39 pm",
"content": "So this is where it gets strange. In Dave's video he specifically addresses the problems at higher frequencies. But this is kilohertz range! I've even tried hooking up a signal generator with a really short coax cable. The weird part is that the signal doesn't look square at lower frequencies (roughly 330 Hz in my example), but at 33 kHz it is just fine. The probe behaves similarly. How can an impedance mismatch be such a problem at 300 Hz?Oh, and the effect is more pronounced with AC coupling and less with DC coupling!"
},
{
"post_id": "",
"author": "beowulfenator",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 13, 2018, 05:39:49 pm",
"content": "Holy cow, you're right! The other channels are fine, it's just CH1 that's weird!"
},
{
"post_id": "",
"author": "ArthurDent",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 13, 2018, 06:17:41 pm",
"content": "It looks like what you were describing as compensation problems could actually be capacitive decay. If you say the trace looked o.k. with 330hz and a x10 probe but the x1 gave this bad display, I wonder if the x10 probe would look similar at 3hz input, because it would have a longer time to decay that you won't see at 330hz.Try putting a capacitor in series with the x1 probe on CH2-4 and see if you can simulate the same condition. You probably will need a fairly small cap to get the same waveform. If this can be verified it means there is a cap in series with CH1 but not CH2-4 the way you have it now set. If the 4 channels are set exactly the same but CH1 give a different display, it may be a dirty switch/relay that shorts out the cap to go from for A.C. to D.C. coupling."
},
{
"post_id": "",
"author": "beowulfenator",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 14, 2018, 08:12:46 pm",
"content": "Quote from: ArthurDent on September 13, 2018, 06:17:41 pmYou're right! A capacitor in series makes other CH2-4 behave like CH1. At 100 nF and above there is no effect. At 1nF the effect is greater and at 10nF it is less pronounced. Channels are configured exactly the same (DC coupling).So do you think it's because of a problem with the CH1 relay? A dielectric gap between relay contacts that should normally be shorted?"
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 15, 2018, 11:42:35 pm",
"content": "Quote from: beowulfenator on September 14, 2018, 08:12:46 pmOr a crack somewhere later in the high impedance circuit before the FET buffer. The whole thing is part of a hybrid.Compare the DC response of channel 1 with the AC response of any of the working channels. If they are identical, then the problem is probably with the relay."
}
] |
2025-10-17T18:25:11.206273
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-4-ghz-receiver-with-adc-output/
|
2.4 GHz receiver with ADC output - Page 1
|
[
{
"post_id": "",
"author": "paranoid_emailer",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "February 28, 2014, 10:24:23 am",
"content": "Hi,I am looking for a 2.4 GHz receiver chip that outputs baseband digital I/Q data, with a sampling rate of around 40 MSPS.I realize that most SDRs output digital data, but the ones with large enough sampling rates tend to be expensive (~$400 for bladeRF, ~$800 for the Ettus USRP) and cover a much larger frequency band than I need. The receiver chips I've found are either:a. designed for certain modulation schemes (e.g. ADF7242) with no way of accessing the ADC outputs, orb. very expensive and cover a much larger spectrum than I need (e.g. AD9361, LMS6002D)Do there exist 2.4 GHz receivers with ~40MSPS ADC outputs that are reasonably cheap (< $50)? Alternatively, how difficult would it be to design one myself (someone who knows nothing about microwave circuits) in a few months?Thank you."
},
{
"post_id": "",
"author": "marshallh",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 28, 2014, 07:43:47 pm",
"content": "Do they exist? Sure. Are they cheap? No."
},
{
"post_id": "",
"author": "Kryan9",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "February 28, 2014, 09:38:21 pm",
"content": "There are options, but \"Cheap\" depends on how lucky you are at getting it right on the first try of DIY.If you want a relatively narrow band with your own software solution, you could try emulating the HackRF approach with a Maxim Wifi Transceiver. These would convert 2.4 GHz down to the baseband, where you throw on your own ADC/DAC solution with a microcontroller/FPGA and you're good to go.Probably would run around 100-150 USD minimum based on where I'm from, though, so I don't know if that would fly with you."
},
{
"post_id": "",
"author": "paranoid_emailer",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 01, 2014, 11:40:10 pm",
"content": "Kryan9, thanks for the tip regarding the Maxim WiFi receivers - I was not aware those had baseband outputs. Unfortunately, it seems the evaluation boards for those chips are exorbitantly priced. I might be better off getting a bladeRF instead..."
},
{
"post_id": "",
"author": "rfbroadband",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 02, 2014, 04:34:30 am",
"content": "don't even think about AD9361. ADI does not even support medium volume customers (I mean companies) with that chip.... not to mention a hobby project"
},
{
"post_id": "",
"author": "paranoid_emailer",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 03, 2014, 09:55:08 pm",
"content": "Thanks, rfbroadband. Would I find sufficient resources if I get the USRP (which has an AD9361 front-end) instead?"
},
{
"post_id": "",
"author": "NiHaoMike",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 04, 2014, 01:58:24 am",
"content": "What about hack a WiFi card? There are some with open source drivers and well documented hardware."
},
{
"post_id": "",
"author": "rfbroadband",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "March 04, 2014, 05:36:32 am",
"content": "Quote from: paranoid_emailer on March 03, 2014, 09:55:08 pmWell, Ettus is selling the USRP. I assume they have to provide some support to their customers. I don't know what kind of software and APIs they provide, so I would hope using the USRP it would not be necessary for you to program the AD9361 directly. You could request their documentation before you purchase the USRP....."
}
] |
2025-10-17T20:07:02.199977
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-4ghz-amplifier/
|
2.4ghz amplifier - Page 1
|
[
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 13, 2013, 12:34:05 am",
"content": "http://postimg.org/image/c0bj4wcjh/heres the img how i think..is there any way to amplify 2.4ghz wifi signal..i have 3 bars of 5 ...and if you have any diagram how to build one .Thxjust need to know if i can or not"
},
{
"post_id": "",
"author": "AlfBaz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 13, 2013, 01:25:38 am",
"content": "Just tape a coat hanger to your wifi dongle"
},
{
"post_id": "",
"author": "madshaman",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 13, 2013, 01:57:43 am",
"content": "Quote from: zorkwan on October 13, 2013, 12:34:05 amDo you think you will need to ensure that you don't amplify the transmitting signal since it will also be on your antenna? Do you plan to amplify both directions of communication?"
},
{
"post_id": "",
"author": "hedgewallace",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 13, 2013, 02:18:44 am",
"content": "You can buy WiFi boosters. Just put it in an area that has pretty good reception (4 or 5 bars) and it should boost your range a bit.Check out this link:http://www.pcmag.com/article2/0,2817,2372811,00.aspOne thing you might also want to look at is a network power line adapter. it's pretty much an adapter that can transmit network signals from an Ethernet cable through your power cables in your house. You would plug one adapter in near your modem, and the other adapter in near your computer, or WiFi router."
},
{
"post_id": "",
"author": "alxnik",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 13, 2013, 03:18:18 pm",
"content": "wifi is duplex. An amplifier will boost tx signal but rx will stay the same so the link will not be any better. To have a better link you need a better antenna.Check your other post, you will find info there."
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 13, 2013, 05:35:04 pm",
"content": "Quote from: madshaman on October 13, 2013, 01:57:43 amno just the receiver"
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 13, 2013, 05:41:26 pm",
"content": "Quote from: alxnik on October 13, 2013, 03:18:18 pmso you mean that i cant amplify my receiver,only my transmitter ,,cant understand whytheres signal coming from my transmitter to the receiver(antenna) and from my receiver ad a amplifier to get better signal and from there to my usb wifi adapter - and pcantenna- to amp -to wifi adapter- to pc"
},
{
"post_id": "",
"author": "alxnik",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 13, 2013, 08:49:06 pm",
"content": "Quote from: zorkwan on October 13, 2013, 05:41:26 pmI don't think there are any amplifiers that amplify the receiving signal, only transmit. Most probably you will get nothing anyway. What matters is the SNR (signal to noise ratio). If you amplify the receiving signal, you are amplifying the noise too. The only way to reliably get a better link is to get a higher gain antenna which must be directional. A yagi wifi antenna costs about 25 euros on ebay, and I doubt you will find a receiving signal amp (if it exists) with that kind of money."
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 03:52:38 am",
"content": "Just put an LM358 in non inverting configuration with a gain of 1,4"
},
{
"post_id": "",
"author": "Kryoclasm",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 08:43:41 am",
"content": "This works a treat, but it is directional and ugly.http://www.makeuseof.com/tag/how-to-make-a-wifi-antenna-out-of-a-pringles-can-nb/"
},
{
"post_id": "",
"author": "HamiltonHipster",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 09:53:23 am",
"content": "Quote from: NANDBlog on October 14, 2013, 03:52:38 amI was thinking a LM741 because of its superior noise characteristics.Zorkwan, you might want to try the coat hanger or pringles. Is 3/5 bars so bad? does it drop your data rate below whats provided by your ISP?"
},
{
"post_id": "",
"author": "ee.jmlp",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 11:31:54 am",
"content": "put a reflector in a places where the signal does not come to concentrate the received power in the antena. Not every distance will be ok, you must move it according of the power level received. Better if the reflector is concave or parabolic with its focus on the antenna.Aluminium would be okay. Treat wifi singnal as light you cann't see."
},
{
"post_id": "",
"author": "madshaman",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 12:49:47 pm",
"content": "Quote from: zorkwan on October 13, 2013, 05:35:04 pmSo you're absolutely sure the transmitted signal won't get in your amplifier, by reflection or other means? How do you plan to ensure this? (Maybe google \"diplexer\" and \"duplexer\")"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 01:27:14 pm",
"content": "Quote from: HamiltonHipster on October 14, 2013, 09:53:23 amAre you aware that for amplifying a 2.4Ghz signal you need something, which has bigger gain-bandwidth than 2.4Ghz? Which is usually high-end stuff by itself, and you need $$$ equipment to test it if it is working properly or not."
},
{
"post_id": "",
"author": "AlfBaz",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 01:31:11 pm",
"content": "Quote from: NANDBlog on October 14, 2013, 01:27:14 pmOh... Surely he was being sarcastic"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 01:33:32 pm",
"content": "Quote from: AlfBaz on October 14, 2013, 01:31:11 pmOK, I thought someone actually took my LM358 bait..."
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 14, 2013, 02:46:43 pm",
"content": "Quote from: alxnik on October 13, 2013, 08:49:06 pm"
},
{
"post_id": "",
"author": "madshaman",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 03:36:15 pm",
"content": "Quote from: alxnik on October 13, 2013, 08:49:06 pmThere's plenty of surplus high bandwidth amps on eBay fairly cheap, even more in the selective 800-900Mhz, 1750-2200Mhz and around 2.5Ghz for cellular, cellular data and wifi."
},
{
"post_id": "",
"author": "geraldjhg",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 14, 2013, 06:30:54 pm",
"content": "hibuy an amplified usb cable ant take dongle outsidecould work"
}
] |
2025-10-17T20:15:22.555017
| 19
|
electronics
|
beginners
| false
|
https://www.eevblog.com/forum/beginners/2-4ghz-antenna-replacement/
|
2.4GHz antenna replacement - Page 1
|
[
{
"post_id": "",
"author": "IvoS",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "September 07, 2020, 01:41:23 pm",
"content": "I have ALIGNA10 transmitter(RC hobby) which I believe is rebranded FUTABA that transmits on 2.4GHz.The antenna on the radio broke off. The quick fix would be to replace it with 2.4GHz antenna with a SMA connector as for examplethis onefound on Amazon.or this one. The question is: is it OK to pick any 2.4GHz antenna and it should work or do I have to look for some other specifications? Thanks in advance."
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 07, 2020, 11:44:08 pm",
"content": "double post not allowed...https://www.eevblog.com/forum/rf-microwave/2-4ghz-antenna-replacement-253060/msg3223080/#msg3223080"
}
] |
2025-10-17T17:42:54.681988
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-4tft-mcufriend-display/
|
2.4tft mcufriend display - Page 1
|
[
{
"post_id": "",
"author": "mskumar84",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 24, 2017, 11:37:38 am",
"content": "hii am planning to interface 2.4tft lcd to msp430 pls help me to proceed further"
},
{
"post_id": "",
"author": "Jeroen3",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 24, 2017, 11:49:27 am",
"content": "You should be a lot more specific with your question. Otherwise everyone just assumes you have mistaken eevblog.com for google.com."
},
{
"post_id": "",
"author": "mskumar84",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 26, 2017, 04:42:06 am",
"content": "hii am using msp430f447 in my project i am planning to interface 2.4tft lcd of mcufriend company .... i want to know the flow of itwith regardssenthil"
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 26, 2017, 11:00:51 am",
"content": "Lots of google hits on \"mcufriend\" and libraries.Here is one that shows a solution for the codeing required. You might haveto port it.http://forum.arduino.cc/index.php?topic=286790.0Google \"mcufriend msp430\", also a few hits on others work.Regards, Dana."
},
{
"post_id": "",
"author": "Rerouter",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 26, 2017, 11:07:37 am",
"content": "also be aware that there are many different display controllers, so depending on your exact model of display, certain example code may not work."
},
{
"post_id": "",
"author": "mskumar84",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 28, 2017, 11:22:31 am",
"content": "thank u i am working on it"
},
{
"post_id": "",
"author": "kathy",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "August 22, 2017, 10:33:39 am",
"content": "For 2.4\" TFT LCD module, there are RGB interface, MCU interface, SPI interface available. the interface could be custom made.most of 2.4\" TFT are QVGA resolution, with 240RGBX320 dots."
}
] |
2025-10-17T18:50:10.070006
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-54mm-connector-and-1-27mm-connector/
|
2.54mm Connector and 1.27mm Connector - Page 1
|
[
{
"post_id": "",
"author": "cobramostar",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 26, 2021, 08:51:25 pm",
"content": "I have never worked with this programI am interested in whether it is possible to select two different connectors and that it automatically connects the pin to the pin1-1, 2-2, ............if anyone has the time and will to explain in detail how to make this pcb"
},
{
"post_id": "",
"author": "Nusa",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2021, 12:30:51 am",
"content": "What program? You left that detail out.But in general, you'll have to connect the nets between pins before you can use any kind of auto-routing feature."
},
{
"post_id": "",
"author": "varunkoganti",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "July 27, 2021, 02:37:24 am",
"content": "Its just an adaptor kind of thing, it converts 2.54mm pitch headers to 1.27mm pitch headers.I made something like this for my st-link, mine converts (2rows 10 contact)20pin 2.54mm pitch headers to (2 rows 5 contacts)10 pin 1.27mm pitch headers.Please find the link, maybe this would help you.Note - I used SMT headers for mine, the attached one used THT headers, I am referring to the 1.27mm headers.I hope this is helpful.https://github.com/DarkStarLab/ST-Link-V2-Debugger-20-10-Adapter"
},
{
"post_id": "",
"author": "cobramostar",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 27, 2021, 01:26:05 pm",
"content": "Quote from: varunkoganti on July 27, 2021, 02:37:24 amcan i open your fillets in kicadfor my needs it should edit because both connectors are 180 degreesyou see connector 2.54 adapted to 1.27, but I don't understand which wires you use to connect with 1.27, I already have 1.27 on the jtag connector, I thought to adapt it to 2.54 because it's easier for me to use zise to connect it to jtagi would like to do something similar as in the picture Connector_1.27_too_2.54.png"
},
{
"post_id": "",
"author": "cobramostar",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 27, 2021, 05:01:29 pm",
"content": "Quote from: Nusa on July 27, 2021, 12:30:51 amcan you explain how to insert the connector and how to connectwhich options to usethank you"
},
{
"post_id": "",
"author": "cobramostar",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "July 27, 2021, 09:32:12 pm",
"content": "Quote from: cobramostar on July 27, 2021, 05:01:29 pm"
},
{
"post_id": "",
"author": "jpanhalt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 27, 2021, 11:11:14 pm",
"content": "I have been following this thread and still am not sure exactly what you want to do. For example, do you want pin to pin identity with simply a different pitch? Is each pin considered separately or are several pins tied together? Those are not the only questions.In sum, provide a schematic of what you want to do."
},
{
"post_id": "",
"author": "perieanuo",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 28, 2021, 06:04:21 am",
"content": "connecting 20-40 ping between 2 connectors in any schematic/layout software takes less than this debate, it's pointless unless you wanna connect 2500 pin connectors and script it"
}
] |
2025-10-17T17:25:05.492158
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-5_-tft-monitor/
|
2.5" tft monitor - Page 1
|
[
{
"post_id": "",
"author": "arekm",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "February 06, 2013, 08:56:55 pm",
"content": "Hi,I'm looking for a 2.5\" tv or monitor (with video input, so driver needs to be included) with a good resolution.Best would be 640x480 but I guess that's nearly impossible to buy. Real 320x240 would be fine, too (as 320x240 == 320x240xRGB pixels).Any recommendations?"
},
{
"post_id": "",
"author": "Zad",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 06, 2013, 11:58:12 pm",
"content": "Adafruit stock a 320x240 one:http://www.adafruit.com/products/912"
},
{
"post_id": "",
"author": "MikeK",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 07, 2013, 01:21:46 am",
"content": "You can get them on eBay for quite a low price."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 07, 2013, 01:31:22 am",
"content": "Yep, search TFT rearview monitor.If you Google around a bit, you'll find a handful of pages out there talking about how they don't NEED to run on 12v and a bit of hackery will get a few of them running on 3.3v no problem."
},
{
"post_id": "",
"author": "jaqie",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "February 07, 2013, 01:52:07 am",
"content": "if you dont need a housing, and are ok with tearing apart a unit, this looks good at first glance?http://www.amazon.com/MONITOR-COLOR-CAMERA-TESTER-OUTPUT/dp/B005FIX5FE"
}
] |
2025-10-17T20:26:17.549647
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-5a-full-fet-bridge-driver-who-needs-so-much-current/
|
2.5A full FET bridge driver - who needs so much current? - Page 1
|
[
{
"post_id": "",
"author": "fsky",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 24, 2015, 06:36:46 pm",
"content": "Hello, recently I was looking at Intersil HIP4081A full bridge driver:https://www.intersil.com/content/dam/Intersil/documents/hip4/hip4081a.pdfI am wondering, what does it actually mean 2.5A gate driver current limit? If we have a FET transistors' gates on all outputs in typical application circuit, why would anyone need so much current, since FET gates need so little of it? Is it designed to drive stuff directly from IC pins, without transistors?"
},
{
"post_id": "",
"author": "mos6502",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 06:54:11 pm",
"content": "A FET gate is basically a capacitor. So turn on the FET, you have to charge the capacitor. The faster you charge it, the faster the FET turns on. The faster you dischage it, the faster the FET turns off. The gate charge is given in the datasheet. To calculate how much current you need, just use the formula I (A) = Q (C) / s.To get fast sub-microsecond switching times on big FETs, you'll find you need a couple of amps of gate drive."
},
{
"post_id": "",
"author": "Ribster",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 06:57:31 pm",
"content": "You can use a simple NPN and PNP transistor in a complementary circuit.Kind of like a type B amplifier. This is noisy on the power supply because of the short when they are on at the same time, but it's a cheap FET driver."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 07:02:26 pm",
"content": "Quote from: Ribster on August 24, 2015, 06:57:31 pmAre you talking about configuring the BJTs as emitter followers? If so then there won't be any shoot through."
},
{
"post_id": "",
"author": "Ribster",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 07:21:35 pm",
"content": "Quote from: Hero999 on August 24, 2015, 07:02:26 pmNope, kinda like this:"
},
{
"post_id": "",
"author": "Chris C",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 07:30:04 pm",
"content": "The gate does act as a capacitor, but that alone doesn't explain why such large gate drive currents are needed.A very simplified explanation: There's a second capacitor between the gate and the other terminals of the MOSFET. The faster you switch the MOSFET, the faster energy is transferred across this capacitor, back to the gate. The end result is that it appears to actively fight your attempts to switch it quickly. Once you get down to switching speeds of 1us is when it typically starts becoming noticeable. Below that, you soon get into territory where everydoublingof switching speed requires aboutfour times more current.That is why you see, what at first glance, appears to be insanely high current capabilities on fast MOSFET gate drivers. And is one major reason why switching power supplies fall short of 100% efficiency. Switching the MOSFET faster decreases resistive losses in it, and heating, caused as it passes through the linear (half-on) region. But at some point the exponentially rising gate current required to do accomplish that exceeds what you save.Of course, this exponential relationship works both ways. So you might be pleasantly surprised to find that DIY gate driver circuit, even though it'll probably top out at 500mA, will only be about 2-3 times as slow as the HIP4081A providing 5 times more current."
},
{
"post_id": "",
"author": "rx8pilot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 07:31:12 pm",
"content": "If you charge the FET gate very fast quickly, the FET spends very little time in the linear region of it's operation where huge amounts of heat is generated. In a bridge driver, the FET is generally being turned on/off quickly and continuously. High current drivers are good for a high efficiency design. The 2.5A is only delivered for a VERY brief moment to get the capacitance of the gate fully charged at which time the current flow effectively drops to zero.The down side is that when you turn it on/off really fast, parasitic inductance in the devices and the PCB (even tiny ones) can cause ringing that should be considered. Ringing can create conducted and radiated emissions that will interfere with the circuit and other circuits. It can also destroy the FETs if it is bad enough."
},
{
"post_id": "",
"author": "fsky",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "August 24, 2015, 07:56:39 pm",
"content": "Quote from: mos6502 on August 24, 2015, 06:54:11 pmThank you, it's clear for me now.I was stuck with ideal models of devices for too long now.Also, thanksChris Cfor your input, that's some very interesting behavior of FETs that I've never heard aboutI think that the topic might be closed now, thank you guys"
},
{
"post_id": "",
"author": "max_torque",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 08:16:24 pm",
"content": "It's also worth noting that how much current a FET driver can transiently handle is to some degree a result of the necessary low impedance of that driver, required to keep the FETs gate at a known voltage. ie, because the gate is capacitively and inductively coupled to the Drain and Source, high voltage transients on these pins also act to change the Gates charge. In order to prevent these transients from changing the state of the gate, those charges must be clamped, and this is what the low impedance of the driver achieves"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 08:31:47 pm",
"content": "Quote from: Ribster on August 24, 2015, 07:21:35 pmThat's what I thought. The BJTs are configured as emitter followers so there will be no shoot-through."
},
{
"post_id": "",
"author": "Ribster",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 09:21:32 pm",
"content": "Quote from: Hero999 on August 24, 2015, 08:31:47 pmAm i wrong that the NPN and PNP will be on at the same time ?At the transition from high to low and low to high, doesn't the commutation of the output state makes the NPN and PNP conduct at the same time?"
},
{
"post_id": "",
"author": "nuno",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 09:23:00 pm",
"content": "You'll find drivers for even more than those 2.5A.Some (big) FETs have like nFs of gate capacitance, but in fact it is a little more complex than that; the capacitance will change while you charge it, so we usually talk about charge (in Coulombs, or nano Coulombs nC - that's the useful information you'll find in the datasheets).And then you may have 2 or more FETs in parallel, driving your current drive requirements even further up."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 09:56:57 pm",
"content": "Quote from: Ribster on August 24, 2015, 09:21:32 pmIt's not possible for both the NPN and PNP transistor to be switched on simultaneously.This is the reason why there will be crossover distortion, if the circuit is used as a linear amplifier"
},
{
"post_id": "",
"author": "eneuro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 11:26:04 pm",
"content": "Quote from: Hero999 on August 24, 2015, 09:56:57 pmI've used BC337/BC327 in this 3 phase 5V MPU (ATTiny85) based driver, where three MPU pins are used to controll (on/off) low power 3 phase loadHowever, fast 1N4148 diodes are added and additional resistors to be able switch desired phase on/off and protect transistors from inductive spikes, etc.I've used also successfully two of those phases to drive simple isolated DC-DC low power full-bridge SMPS, so I hope there is no shoot-through since circuit simulators in simple cases ar efine and I've got similar results in other sim too"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2015, 11:52:54 pm",
"content": "2.5A isn't nearly as much as it sounds -- it's obviously not 18V * 2.5A = 45W continuous output power, or even 1/4 of that (which would be realistic for a circuit at those full ratings into an AC load). It is that much capacity, peak, but this doesn't get you as far as you might imagine when considering it has to be done in a hundred nanoseconds or less.As mentioned, the gate has a capacitive characteristic, so it takes peak current to make its voltage move. It also has some internal resistance, which is due to the gate being constructed from a thin layer of aluminum or polysilicon, as well as other internal losses.The important datasheet figure is Qgs(tot), the total gate charge required to go from off to on (the voltages are specified; since E = Q*V, it takes more energy to reach a higher voltage, so the voltage is also important information for this parameter).The internal losses of both gate and driver (which has an equivalent Rds(on) or output resistance specified in the datasheet) add in series, and this limits how fast the gate can be swung.Typically, during turn-on or turn-off, a transistor will experience Iload * Vsupply for approximately the duration of switching. If it's a power transistor on the mains side of an SMPS, that might be 20A and 320V, so the peak power is extreme! To achieve useful efficiency, the duration of this power dissipation must be kept to a very small fraction of the cycle, never more than 1/20th and typically under 1/100th. Or for a typical 100kHz switching frequency (Tcycle = 10us), under 100ns.Combining all these facts:We can estimate the switching speed as:t_r ~= 2 * (Rdriver + Rgate) * Qg(tot) / (Vgs(on) - Vgs(off))A typical example might have Rdriver = 4.5 ohms (typical of parts like the HIP4081*), Rgate = 5 ohms, Qg = 100nC, and Vgs(on) - Vgs(off) = 10V (usually 10 and 0V, respectively). This gives an equivalent capacitance Qg/Vgs = 10nF, a time constant of 95ns, and a full switching time about 190ns.(*Note, by the way, that 2.5A peak is only possible when the output is shorted to the opposite supply, which is only true for the most brief of instants during switching -- much of the time is spent at half that voltage, so the average current during switching must be lower, which is why it's often valuable to use even *larger* drivers!)And that's without using a series gate resistor, which is often desirable to avoid parasitic oscillations. (The AC small signal equivalent of the gate terminal, actually looks like a small negative resistance, giving rise to oscillations in the 20-100MHz range, if the gate circuit has too much inductance and too little resistance.)At 100kHz, 190ns is 1.9% of a cycle, so if we're dissipating 1000W during switching (typical of a 100V, 10A application), the average switching loss is 19W -- better have a heatsink! But not only that; this adds with conduction losses, so the total will be higher.Conduction losses are due to Rds(on), which might be 75mohm for a device in this class. P = I^2 * R = 7.5W, but this is only drawn during half the waveform, so the dissipation per transistor is half this, or 3.75W.So you can see, the switching losses can be quite substantial, and there is very good reason to keep it fast!But speed comes at a price, and you must deal with the consequences of that risetime. All inductances and capacitances in the circuit get involved, whether you thought they existed or not! That includes stray wiring inductance as well as component parasitics. A simplified (first order) analysis of this can be made as well, but goes well beyond scope here.Tim"
},
{
"post_id": "",
"author": "rx8pilot",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 02:37:36 am",
"content": "Quote from: T3sl4co1l on August 24, 2015, 11:52:54 pmI learned that lesson the hard way after laying out a few SMPS circuits. I carefully calculated everything except the parasitic inductance and capacitance of the PCB itself. It was a mess that I could not figure out. I found some resources that focused on PCB layout that were very helpful. With the exact same schematic and components - a super tight layout turned out to deliver pretty good performance. The effort primarily surrounded the issues of fast FET switching."
},
{
"post_id": "",
"author": "bingo600",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 07:50:07 am",
"content": "Quote from: eneuro on August 24, 2015, 11:26:04 pmCould we have a schematic of your driver please ?/Bingo"
},
{
"post_id": "",
"author": "nuno",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 08:57:14 am",
"content": "Quote from: eneuro on August 24, 2015, 11:26:04 pmFET/IGBT driver design is a very interesting topic on its own. That transistor topology only gives you 5V - Vbe(~4.3V) output when \"high\", since you're driving it with a microcontroller (assuming its running at 5V); may be perfectly fine in your application, but 4.3V gate drive is probably not the typical case when you need to use such circuit to up the drive current.Quote from: T3sl4co1l on August 24, 2015, 11:52:54 pmActually I think is double that value, 38W, you forgot about the \"fall\" transition.bingo600, here's another example of discrete FET drivers with low latency you can look at if you like the subject (it's one driver for a NMOS and another for a PMOS, both repeated):https://github.com/vnevoa/DiffTrike/blob/MarkIV_RasPi_NJAY/Electronics/PowerBridge/hw/bridge-fet-drivers-schematics.pdfThey're far from perfect, but they do drive wheels"
},
{
"post_id": "",
"author": "Chris C",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 09:38:14 am",
"content": "I just wanted to say that I love this quote.Quote from: T3sl4co1l on August 24, 2015, 11:52:54 pm"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 12:52:22 pm",
"content": "Quote from: nuno on August 25, 2015, 08:57:14 amI cheated.It's actually more like a triangle, where voltage is rising and then current is falling (and vice versa at turn-on), so that the area is half that of a rectangle having the same width and height. But it happens twice per cycle, so it still comes out right. (The same occurs when you look at gate drive power, where you charge and discharge the equivalent capacitance Ceq = Qg/Vgs, which holds energy e = 0.5 CV^2, half of which is stored, half dissipated in the gate resistances; but it doubles per cycle so you can use e directly as gate switching energy.)38W of course is the figure for two devices, which is more important on a system level.Tim"
},
{
"post_id": "",
"author": "nuno",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 01:25:06 pm",
"content": "Ahh! Yes you're right. I use that formula (Pd(sw) = V x I x f x (tr + tf) * 0.5) too.You may not believe, but many cheap chinese electric bicycle BLDC motor controllers do asynchronous rectification instead of synchronous, even though they have the all hw in there."
},
{
"post_id": "",
"author": "eneuro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 03:17:02 pm",
"content": "Quote from: nuno on August 25, 2015, 08:57:14 amYep, you are right, it is closer to 4V than 5V, but it doesn't matter in this simple SMPS, while even using such poor inductive coupling in quick made transformer for tests at ratio 1:2.5 using ferrite beard (pri: 8T sec: 20T) I was able easy get in this galvanic isolated DC-DC 11.37Vmax after full wave rectifier using ATTiny MPU shown above to drive this toroid primary using additional AC coupling with 100nF ceramic caps at programmed 400kHz switching frequencyQuote from: bingo600 on August 25, 2015, 07:50:07 amI wouldn't like reveal detailed schematics for the moment, while after one of my projects is finisched PCBs made in China will be available on my website and maybe I'll publish in local electronics magazine snapshot of this work, so the requirement is that it can not be published before official publication in magazine, so I wouldn't like to talk to much about it, for the momentHowever, nothing fancy in the case of two phase there and more tricky part is driving those pins when we need three phase, since we need leave one of the MPU control pins floating, so knowledge of assembler can be helpfull if we wanted on not too fast MPU (1MHz-8MHz) get nice symetric timing of all phases-at 400kHz speeds things like number of RJMP cycles matters (compilators can generate optimized code which will not get you perfect timings) and I've made compensation for things like this in implemented MPU delays to get exact timing of all phases at given switching frequency"
},
{
"post_id": "",
"author": "Chris C",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 07:19:32 pm",
"content": "Quote from: nuno on August 25, 2015, 08:57:14 amNice drivers. I use something almost the same. I haven't yet figured out how to make the schematic large enough to read the part labels, but see that first resistor, through which the input signal passes to the pull-down transistor's base? I add a Schottky diode in parallel with that. This accomplishes two things:1) When connected to an MCU or other device which can sink current, and it switches to logic low, the Schottky conducts and bypasses the resistor. Allowing the full available sink current to drain the base charge, and improving transistor turn-off time. It does so even though there's an anti-saturation diode between that transistor's base and collector, they work great together.2) When it switches to logic high, the Schottky is reverse biased and does not conduct. Instead, it acts as a capacitor, in the neighborhood of 10pF. This is a significant portion of the the transistor's base capacitance. And so, by again bypassing the resistor, it improves turn-on time some too.Both of which make the the driver more efficient, and reduce losses in the MOSFET. Not bad for one extra component.Additional improvements? Add a little more capacitance, 10-20pF, in parallel with the Schottky, so that the total exceeds that of the transistor's base capacitance. And replace the resistor that feeds the pull-up transistor's base with a constant current source. But these provide smaller improvements, and I usually don't bother. I always use the Schottky, though."
},
{
"post_id": "",
"author": "poorchava",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 07:42:54 pm",
"content": "For those who might now know: the key term is 'Miller capacitance' or 'Miller effect'. In datasheets it's usually referred to as Cgd. In great simplification: as your fet starts to turn on or off, the voltage at the drain changes rapidly and that high frequency signal propagates through Cgd and counteracts the change of gate potential.This is why you can find drivers capable of 20A+ peak currents (eg. Microchip makes those). I have once designed a driver which had to provide over 40A of peak drive current (and yes, the EMI from this was extreme). Actually the gate drive consumed about 60 W of power by itself"
},
{
"post_id": "",
"author": "eneuro",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 08:05:02 pm",
"content": "Quote from: Chris C on August 25, 2015, 07:19:32 pmUnfortunatelly, I can't see any of them capable to provide negative Vgs, which should help overcome many problems eg. in half-bridge in synchronous buck converterIsn't negative Vgs a must in more demanding applications?Probably, i would use rather isolated DC-DC to provide positive and negative +/-15Vgs ON/OFF with optoisolated a few Amps gate driver configured to work with eg. +/- 12Vgs.I've used cheap TLP351F succesfull in such configuration, since its VCC is above 24V as I rememberUpdate: Yep, TLp351F has:Code:Power supply voltage: 10 to 30 Vso I've choosen +/12V to operate within safe 24Vcc and +/-12Vgs"
},
{
"post_id": "",
"author": "nuno",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 08:34:11 pm",
"content": "Quote from: Chris C on August 25, 2015, 07:19:32 pmThank you. It's the \"Raw\" button on the right on top of the image, but here's a direct link:https://github.com/vnevoa/DiffTrike/raw/MarkIV_RasPi_NJAY/Electronics/PowerBridge/hw/bridge-fet-drivers-schematics.pdfI just noticed the schottky diodes's symbols somehow ended up the same as PN ones, I'll have to change it when time permits. The github project under \".../PowerBridge/...\" has a 25V 25A DC motor controller project with all design files for schematics (KiCAD but there are PDFs of all schematics), pcbs and fw for whoever wants to look.There are a few \"problems\" with these drivers, but I also wanted to keep component count down, as much as desperately possible. For example, the low driver doesn't keep the FET off when the input is floating (in my application this isn't a problem because the high side ones are guaranteed off) and the top output transistor is always dropping 12V (and it needs a constant, although tiny, load, guaranteed by the FET's gate-source resistors).Thanks for the suggestions below.Quote from: Chris CI currently don't have any of those drivers with me, but I was pretty happy with their switching latency, basically \"zero\" (switching time in my app is decent too). I have some scope shots, including comparison with no anti-sat diode at all and with 1N4148 as anti-sat, but not here with me. When I get my hands on the drivers again I'll try that 2nd schottky to see what's the difference - as it is, the driver's output (loaded with the FET) starts reacting \"instantly\", but from your description I guess it goes up/down faster (it is actually irrelevant in my application, because the phase's di/dt is being limited by parasitic inductance at the FET's source (which is bad and good) - hey, I'm still learning!).Quote from: Chris CI see. The input's 0->1 transition, being fast, goes through the \"schottky's capacitance\" bypassing the resistor."
},
{
"post_id": "",
"author": "nuno",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 08:37:57 pm",
"content": "Quote from: eneuro on August 25, 2015, 08:05:02 pmNope, they do not provide negative turn off voltage. It wasn't necessary in my application, and as far as I've seen, that is used, typically, only with IGBTs (because they are more stubborn to turn off I guess, with that \"current tail\" or \"trail\" or whatever).Quote from: poorchava on August 25, 2015, 07:42:54 pmJust to add another Miller term: \"Miller plateau\"Quote from: poorchavaNow that seems like a lot of fun!"
},
{
"post_id": "",
"author": "Chris C",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 09:16:35 pm",
"content": "Quote from: nuno on August 25, 2015, 08:34:11 pmI only recently found out a Schottky was an option for the anti-sat diode. I'd always assumed it would limit the base voltage too much, and therefore limit current through the transistor. But I have not yet had a chance to actually try it and see. It sounds like you've performed this experiment. Don't go through too much trouble finding scope traces, but since you went with the BAT54, I assume it did in fact work out better than the 1N4148?Also, now that I can see the schematic (thanks for the help on that), and realize the anti-sat is actually a Schottky, then the Schottky I suggested adding is not the optimal choice. The base voltage will never be high enough that my Schottky will significantly assist with turn-off, other than acting as a bypass capacitor. Better to just use a capacitor instead! If you get a chance to try it, I'd recommend starting with a 22pF."
},
{
"post_id": "",
"author": "nuno",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 09:22:28 pm",
"content": "Quote from: Chris C on August 25, 2015, 09:16:35 pmMuch better, no comparison possible as far as I remember. No visible latency at all with the schottky (no time spent removing junction charge). I have the shots easy to reach, it's just that I'm not at home, I'll post them later.Quote from: Chris COk, thanks. I'll sure try it. I have seen the cap usage to assist removing the bjt from saturation but I think when I saw it it was something like \"you can use the caporyou can use the diode\", never gave it a thought about using both methods."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 10:51:03 pm",
"content": "Quote from: poorchava on August 25, 2015, 07:42:54 pmThis is absolutely true, and a large part of the operation of MOSFETs!But be careful with the quantities. Measuring MOSFETs by capacitance is highly ineffective...The charge equivalent capacitance is typically more than quadruple the value of Cgss!The reason for this is dual: not only do you have to charge Cgd (Miller effect), but all terminal capacitances (Cgs, Cds and Cgd) vary considerably with drain and gate voltages. Take careful note of what voltages Cgss is measured at, then refer to the plot of capacitance versus drain voltage. Ask yourself... is that *really* useful?So, while you can use capacitance, do make sure it's the charge equivalent: Ceq = Qg(tot) / Vgs(on), as in my example.Tim"
},
{
"post_id": "",
"author": "nuno",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 25, 2015, 11:41:16 pm",
"content": "3 shots, without any anti-saturation diodes nor other prevention techniques (note the time scale, different from the next 2 shots), with a 1N4148 and with a BAT54, on the PMOS driver (this one is non-inverting). I can't remember exactly but some of the interference is probably measurement artifacts, is not physically possible to measure these 2 signals with short GND clips. Yellow is driver input, can't remember anymore what the blue trace is, the hump at the end looks like the Vcc + Vfw(intrinsic-diode) which should be visible at Vd, but dropping only 9V suggests it's Vg. Anyway, for the comparison at hand I think Vg or Vd is irrelevant, it represents the driver's output."
},
{
"post_id": "",
"author": "Chris C",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "August 26, 2015, 12:13:53 am",
"content": "Oh yeah, that BAT54 is performing very nicely. Really about as good as I've seen with a standard switching diode for anti-sat, and either the Schottky or capacitor bypassing the input resistor. Thanks!"
}
] |
2025-10-17T19:34:51.758249
| 32
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-5kw-dc-to-dc-boost-converter-project/
|
2.5kW DC to DC Boost Converter Project - Page 1
|
[
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 05:31:19 am",
"content": "My first post so please be gentle.I'd like a little input from the brain trust on a project I'm working on.12V to 48V at 50A (yes, it's a big one) DC to DC converter.This supply will be power a high frequency power amplifier used for single sideband communications.If any of you are amateur (ham) operators then you'll know the deal. Current draw will be constantly swinging between virtually zero load to max.I am having colleague of mine supply this custom isolated converter and due to the nature of the load, I require a very clean and stable output.Ripple AFAIK will not help obtain decent IMD and any noise will probably to a degree get amplified. Of course I will have switched LPF on the amplifiers output but I don't wish to create other problems by having a 'dirty' power supply.My question is, what filtering and regulator topology do you suggest as a minimum to give a clean & stable output on the above.I will have a very stiff DC input supply so there are no worries at all in that department.Provisional board design enclosed for your viewing pleasure.Appreciate your thoughts and input.David"
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 08:10:49 am",
"content": "Why do you want to start from 12V?"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 08:24:40 am",
"content": "Hi Mike,Well in answer to your question I just want to see if a one box solution can be accomplished to power a pair of high power LDMOS RF devices without involving any other external equipment in a motor vehicle such as a 28V alternator (easier to boost to 48V) or a 48V alternator. The fact is I drive a diesel so no ignition to interfere with and the fact that with SSB operation while the peak current draw is high the average current requirement is I believe going to be considerably less and the 'shock' can easily be handled by a higher than stock quality automotive charging and battery storage system.Yes, I know it's a crazy concept.I happen to like crazyDavid"
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 08:35:50 am",
"content": "What run-time do you need ?Four lead-acid batteries, charged in parallel and discharged in series may be a viable solution - very simple, very electrically quiet. If it's a push-to-talk type of thing you could have them switch between charge and discharge on the mic key - you may want to use MOSFETS rather than relays to avoid a loud clunk.Or RC Lipos - more complicated charge scheme but potentially faster charge"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 08:47:37 am",
"content": "It would be a press-to-talk operation with less talk to and more listenExcuse my ignorance but what is RC Lipos. Google doesn't know nor do I?I'm afraid I'm not really interested in carrying four batteries and as I stated above I really want a one box solution, with built-in DC converter with the end result power amplifier having around 15db gain.100W RF in and 1.5kW RF out, simples.David"
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 08:55:31 am",
"content": "Quote from: Transmitter Man on October 01, 2017, 08:47:37 amlithium-polymer batteries for radio-control models etc.QuoteYour >200A input cables are going to be pretty bulky though, and it will be hard to get good efficiency at that current.What is your incoming supply going to drop to when you are pulling 200A from it?I would guess you could probably build something with lipos in a similar volume to a 2.5kw DC-DC converter"
},
{
"post_id": "",
"author": "daqq",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 09:24:57 am",
"content": "This might be interesting:http://cds.linear.com/docs/en/design-note/dn1043.pdf"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 09:26:35 am",
"content": "Hi Mike,DC power cable run will be circa 10ft long from battery to input of converter.I will be using 4/0 power cable rated at 400+A.DC voltage drop using this calculator:http://www.marinewireandcable.com/p/voltage-drop-calculator.htmlis .05V !The above is based on 12V at the battery end however as you probably know batteries with charge going in typically measure between 13.8-14.2.Your 200A draw calc is of course correct but this is instantaneous peak current draw and way higher than average draw.If you have ever used a HF, VHF or UHF transceiver in the mode of single sideband (SSB) then you will know that when you're not speaking their is little if any current draw on the power supply, the peak current draw in this particular case may be 200A for speach peaks (I've yet to crunch the numbers) but the average current is far less. It really is, honest.My stock vehicle and it's not an executive saloon comes standard with a 140A alternator however the only mod I introduce, and I have used several in the past is to connect a superior external voltage regulator system:http://www.adverc.co.uk/which offers greatly improved charging of one or more battery banks. Your headlights run far brighter than normal!Please in this particular case forget peak current draw and concentrate on average current draw.A good quality commercial battery can handle instantaneous peaks pretty well even without introducing a snake oil stiffening capacitor as sold to many high end automobile stereo op'sBTW, I love that baggage handling X-ray machine of yoursDavid"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 09:32:36 am",
"content": "Hi daqq,That paper talks above a voltage divider. I'm not sure it pertains to boosting voltage.Maybe I read it wrong.Thanks for your input.David"
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 09:34:16 am",
"content": "Quote from: Transmitter Man on October 01, 2017, 09:26:35 amOne isssue is that a DC-DC converter must be sized for the peak draw, but capacity of batteries(used within their peak current spec) may not have to be all that large."
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 09:45:53 am",
"content": "Yes, agreed Mike.I will admit I had not factored that very important point in, so I'll see if the first converter falls down when used in anger.I have a feeling it may not like the load but we shall see.David"
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 10:14:39 am",
"content": "Quote from: Transmitter Man on October 01, 2017, 09:45:53 amOf course you'll also need to take precautions to stop any significant amount of RF getting back to the converter, as that could cause Very Bad Things to happen. That, along with keeping it stable with the rapidly chaging load is going to make the converter design rather challenging."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 10:43:47 am",
"content": "Parallel the boosts as in the attached"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 11:16:54 am",
"content": "A filter on the output of the converter or and input of the amplifier should stop any RF getting back into the power supply.I have requested as good regulation as he can design in so we shall see how that holds up.I can feed a low power load in and monitor on both scope & spectrum analyzers both of which I have available.Treez,There's malware in that file!David"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 11:56:59 am",
"content": "To go back to my original question.Can anyone suggest a better than average output regulator and hash filter circuitry or topology as I'd like to have this first build as good as I can get it minimising changes next time round.David"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 12:52:36 pm",
"content": "Did you provide a suitable noise spec and measurement condition for your colleague to test the power supply design at?If the PSU doesn't meet its specs, it's a bad PSU. End of story.Tim"
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 01:57:38 pm",
"content": "A couple of pointers:While SSB has high peak to average ratio, most class AB power amps have an unfortunate behaviour in that the drain current is proportional to the square root of the power backoff ratio, so at 10% power output you are still drawing 33% of whatever PEP current is, which is pretty horrible.Given the silly large 12V currents in play I would think long and hard bout a polyphase design it will raise the ripple frequency making it far easier to filter, as well as reduce the strain on the caps, Linear Tech have the sand you need for this..For the same reason, something transformer based rather then a classical buck might be a better choice, maybe something in the ZVS PSFB style.You really want the DC/DC close to the batteries, nothing good comes from long leads on the input side where filtering is even more of a pain.As far as filtering goes, measure first then design based on what you find, higher switching frequencies make filtering easier (again arguing for multiphase converters), but you are probably looking at a few stages of LC filters (You do not want too much Q here or the amp board will probably act out)."
},
{
"post_id": "",
"author": "mikeselectricstuff",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 02:23:56 pm",
"content": "What is the current envelope like ? if the peak currents are the peaks of the AM input, then a big cap on the output may significantly reduce the peak current requirement for the DC/DC converter"
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 02:45:13 pm",
"content": "PSU...do it with parallel smps's...I have sent you 5 posts which got kicked out due to being >1MB..let me try with this gem of knowledge attached."
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2017, 05:15:24 pm",
"content": "Treez,Thanks for posting again but I opened up both files and there was nothing there.Is anyone else seeing this information?I do not normally have issues reading pdf's.Hi Tim,Thanks for your input.In answer to your question I did not give him spec for the output other than from an isolated design I required as clean and regulated output as he manage.So, not very scientific I'm afraid.I need an attainable noise figure from you guys?I am also aware that a supply rail with poor regulation will have a negative affect on intermod distortion from my amplifier.I intend using a pair of underun 1500W LDMOS to obtain better than average IMD at 1500W peak output so do not wish to defeat this objective with a poorly regulated supply.I have asked what load/s and other test equipment he has available to test and monitor the output.Hi Dan,I was hoping that you might just pop by :-) as I know you know your RF.I will run your comments past my converter man although I may just have the existing board made & populated and see where is falls down myself.I hear you regarding the power cables. My last mobile amplifier was strictly low voltage bipolars but at around 800W my DC supply rail dropped only 0.2V down to 14V on key down CW however I have never experimented with switchers at this power so it will be interesting to see any results.David"
},
{
"post_id": "",
"author": "fcb",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 05:33:30 pm",
"content": "I would start by making the design modular - perhaps divide it down into 4 or 8 identical modules. They can share an input and output buss.Use a boost controller IC (something like the LM5122) that supports synchronous rectification, and lock all the units to the same clock (and if necessary phase shift each of the clocks (master oscillator and some div-by-8 logic).The current sharing might be interesting to get right, but in practice I've done something a bit like this and the resistance of the output wiring (or your first stage of output filtering) along with carefully trimming of each module worked in my application (I ended up with four regulators, all set with slightly different output voltages)."
},
{
"post_id": "",
"author": "dmills",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 05:44:02 pm",
"content": "Current mode controllers are the way to go if you are doing boost converters for this, usually very easy to parallel, and do run them phase shifted, much easier to filter.The nasty trap with LDMOS is AM to PM conversion due to Cds and the miller capacitance Cdg varying with applied voltage, this usually shows up not as classical intermod but as cross modulation causing low level copies of the transmitted spectrum spaced at multiples of the switcher frequency to appear in the output, do check for this.I take it you are going for the MRF1K50 in some form (I like the plastic package ones, 30% lower thermal resistance is not to be sneezed at).If you have an RC network from drain to gate to provide feedback you will want to watch this as it can be a route for supply noise to get coupled to the gates, which never ends well, make the bias supply very stiff at AC to minimise this (Big cap to ground from the centre tap of the gate transformer), then make sure you can remove the bias quickly.Regards, Dan."
},
{
"post_id": "",
"author": "ocset",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2017, 06:03:07 pm",
"content": "QuoteI dont understand, i just opened them from the post....its there.i agree about interleaving the smps's...as the attached ltspice shows...much less ripple"
},
{
"post_id": "",
"author": "Jay_Diddy_B",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 02, 2017, 03:54:12 am",
"content": "Hi,Before you go to far down the road with this project, I would check if you can even get 2.5kW out of a 12V battery. You have to consider the ESR of the battery. The ESR will vary with health of the battery, state of charge and the temperature.LTspice modelHere is a model of the battery with an estimated 50mof series resistance. The model also includes a voltage controlled resistor as a load.LTspice ResultsThe upper graph shows efficiency. It is the power in the load divided by the total power dissipated converted to a percentage.The lower graph shows the input current, red trace and the power dissipated in the load, blue trace.The maximum power occurs when the load is equal to the ESR. At this point the same power is dissipated in the ESR of the source, 50% efficiency.Regards,Jay_Diddy_B"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 02, 2017, 04:01:26 am",
"content": "Quote from: Transmitter Man on October 01, 2017, 05:15:24 pmBluh...That's a dangerous spec! You might just end up getting little more than an automotive DC-DC converter. By that, I mean the kind of thing commonly used in car amps: 12V is chopped up, transformed and rectified. Nothing else: no regulation, no filtering (just a wad of capacitors), no limiting, no protection. It's a wonder they manage to even start up, but that's somewhat helped by their poor design (slow switching speed), as is EMI, I suppose.The regulation of such a design is poor. The MOSFET Rds(on), DCR and leakage inductance of the transformer, and Vf of the rectifiers, all add up in series, determining the output regulation (i.e., change in output voltage over change in load current). The line regulation (change in output voltage over change in input voltage) is always 1. In other words: it's nothing more than a DC transformer.That's perfectly possible as all he could \"manage\"!It takes effort to do better: you must add a filter choke, current sense and feedback loop to provide regulation and limiting or protection.Best case: the PSU is designed as modules (as suggested above), where each module has a control voltage input, power input (nominal 12V), and a power current output (Io = V(control) * gain). Note that gain has units of conductance, so this is a transconductance stage. Any number of transconductance amplifiers can be connected in parallel. Currents in parallel add, no sharing to worry about. Finally, an error amplifier sets V(control) based on output voltage feedback, thus regulating output voltage.Because V(control) is always bounded (the error amplifier can't set any voltage outside its supply voltage range), Io(total) is always bounded. You getimplicit current limitingthis way -- it's really quite fantastic, and it doesn't take much more effort than the alternative, which is significantly worse.The main alternative is a voltage mode control. This also has to be wired in parallel, naively, because there's no way to sense current sharing. It's a very poor design, as the current sharing between sections is at the mercy of propagation delays and resistances in each section. If one delay is a little out from the rest, that transformer hogs current and melts transistors; cascade failure ensues. No matter the number of stages, voltage mode control is itself at the mercy of transients, as all it takes is a sudden change in source or load condition to cause an excessive current draw, and psst, bang, there goes all the transistors again.So your options are: bargain basement, unregulated and unprotected; voltage mode, regulated and unprotected; and current mode, regulated and protected.QuoteWell... you tell us, it's your amplifier!How much supply voltage variation is tolerable?How much PSRR does it have? At what frequencies?How sensitive is your receiver? Do you expect to be able to listen to conversations while this supply is running? In which bands?If you don't even have any basic guesses, then test and measure! Vary the supply voltage and see where IMD degrades; couple RFI into the supply and see where it goes; test your receiver's dynamic range and discrimination; etc.We are privileged to work in a field where every possible statement can be measured, tested and calculated. Don't let that opportunity pass you by!Cheers,Tim"
},
{
"post_id": "",
"author": "Jay_Diddy_B",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 02, 2017, 04:24:02 am",
"content": "Hi,You can estimate the bandwidth of a boost power supply by calculating the frequency of the RHP zero:Freq RHP Zero = Vin x Vin--------------------------2 x Pi x L x Vout x IoutAssume that1) A four phase approach is used2) The switching frequency is 100kHz3) Ripple Current = 40%L= 2uHVout = 48VIout = 12.5A (1/4 the total)Vin = 9V (12V source with ESR loaded down 33% of the power in the ESR)Freq RHP zero = 10KHzIt is traditional to have a loop bandwidth = Freq RHP zero / 10 = 1kHzThe control loop will have a bandwidth of about 1 kHz. This will limit the transient response of the power supply.Regards,Jay_Diddy_B"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 02, 2017, 09:10:16 am",
"content": "Tim,The output of this smps should answer some or all of your technical questions:http://power.murata.com/data/acdcsupplies/cps_d1u-2000-48-hx.pdfThe FCC Certified & CE marked broadcast transmitters that are made by my last company used one or more of these until they recently changed to Delta's and they powered similar RF PA's albeit for the FM broadcast band.I am of course looking to produce higher output from a very stiff automotive battery source.David"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 02, 2017, 09:21:07 am",
"content": "Oh good, FCC Part 15, that's an excellent starting point. And not hard to verify!Tim"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 02, 2017, 10:02:24 am",
"content": "Hi Tim,Not Part 15 but Part 73 verifiedPart 15 are pretty much toys Part 73 is for 'professional' broadcast transmitters however as my amplifier will only operate in the licensed amateur radio bands I think the technical requirements regarding emissions are less stringent. I am no expert in this area. I know spurious & harmonic measurements to meet FCC standards however at this time I have no intention of going into production nor am I based in the US I am just content on proving the concept of this mobile HF amplifier project can work.David"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 02, 2017, 11:41:22 am",
"content": "Quote from: Transmitter Man on October 02, 2017, 10:02:24 amWell, that's the thing, isn't it?Can? Absolutely. It's been done before, and will be done again.Will? Who knows. Depends on how good the power supply is. Hopefully you get a satisfactory design, or if it's noisy, you find it's easily filtered/shielded, and all is well.That's the only way anyone can possibly answer your question: with numbers, ratings and measurements. That's why I ask! Until you get the physical article, there is no possible way anyone can address your original question with just the information presented here.Tim"
},
{
"post_id": "",
"author": "Transmitter Man",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 02, 2017, 02:22:06 pm",
"content": "Tim,I will have the first converter built and arrange some testing and will report back, possibly with a video link.Thanks for your thoughts and comments.David"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 02, 2017, 02:23:31 pm",
"content": "Cheers and good luck.Tim"
}
] |
2025-10-17T18:47:40.818936
| 32
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-7v-voltage-clamp/
|
2.7v Voltage Clamp - Page 1
|
[
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 30, 2013, 07:47:14 pm",
"content": "I want to use a solar cell to charge a supercapacitor. The problem is that the open circuit voltage of the solar cell is 6V, and the capacitor is rated for 2.7V. All of the voltage clamp circuits that I have found online use a zener diode with a Vz of the desired clamp voltage. Is there any other way to do it with other components? I was planning on using a voltage divider and suddenly realized the obvious today...the divider is going to lower the voltage even when the solar cell is outputting a voltage lower than 2.7V."
},
{
"post_id": "",
"author": "Jon86",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 30, 2013, 07:48:38 pm",
"content": "A voltage clamp is surely going to be the least efficient way to charge your capacitor in this application. I'd go for a LDO regulator instead, if possible."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 30, 2013, 08:00:02 pm",
"content": "Either a LDO or a switching regulator in SEPIC mode ... for example LT1308 ( you have buck-boost example on page 16 of LT1307 datasheet, lt1308 is just the higher current version of lt1308 :http://cds.linear.com/docs/en/datasheet/1307fa.pdf)"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 30, 2013, 08:11:12 pm",
"content": "The correct way to do this would consist from two \"blocks\"A solar energy harvesting IC to produce a load which is optimal to get the maximum energy from the solar panel.And a supercapacitor charger, which would limit the currents to safe limits, and wouldn't allow you to overcharge.But of course that is not easy nor simple."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 30, 2013, 10:19:51 pm",
"content": "Simplest is a shunt regulator and a blocking diode, or use 2 supercaps in series and a LDO 5V regulator to feed them via a low forward drop diode to disconnect the LDO when not charging."
},
{
"post_id": "",
"author": "mrkev",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "December 30, 2013, 10:54:46 pm",
"content": "Quote from: SeanB on December 30, 2013, 10:19:51 pmJust be carefull with the two capacitors in series as the voltage distribution may not be equal for them... Something like 1meg resistor in parallel with each cap is usually needed."
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 30, 2013, 11:15:48 pm",
"content": "LM2577 SEPIC module from ebay. Panel in one end, stick a multimeter on the outputs and twiddle the trimpot to get your 2.7v output. Job done.ebay search:http://www.ebay.com/sch/i.html?_odkw=LM2577&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.XLM2577+auto&_nkw=LM2577+auto&_sacat=0If it's LM2577 and has 2 inductors, it's the SEPIC variety (can boost and buck to maintain output voltage regardless of input [within limits] -- actually, with 2.7v set as output it can't boost anything to that, but it can buck from 3v+ down to the 2.7v, anything under 3v of your panel is probably wishful thinking for useful power output anyway)."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 31, 2013, 02:25:49 am",
"content": "I like the efficiency of those buck converters, but they are literally twice the size of the rest of my circuit combined. Space is limited since I'm trying to pack this system in an existing landscape light enclosure, so I don't think the converter will fit.How is the Zener inefficient? Will it allow 2.7v to pass into the cap even when it produces voltages in excess of 2.7v? I'm really confused as to how a Zener works."
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 31, 2013, 02:58:14 am",
"content": "Quote from: wilheldp on December 31, 2013, 02:25:49 amIf the voltage is above 2.7v, then yes, from the top of the (2.7v) zener to the bottom (call it ground), is 2.7v (give or take, tolerances etc etc).But the extra volts don't just vanish, the power has to go somewhere.... heat.Let us imagine that your load is going to be fed 100mA, and that your panel is producing that at 6v.The resistor must by definition drop 6-2.7 = 3.3v, if 100mA is passing through that resistor, then how much power is being burned off as heat: 3.3*.1 = 330mW of power, that's a lot of power loss. Gets worse, because the zener also must pass current through it, lets say 5mA, so your resistor passes 105mA (100 to the load, 5 to the zener), increasing the power dissipation further.All that power is thrown away, which for solar applications, is generally the opposite of what you want :-)You also have the problem that if your load stops being a load, that is the amount of current it is drawing drops, because you have a fixed resistor, all that current it was using must by definition now go through your zener, which in the best case get's hotter (now the zener has to dissipate .105*2.7 Watts of power), or in the worst case goes pop.Zener based regulation (and linear regulators in general for that matter) is fine if you don't care much about chucking out useful power, and if the load is fairly constant."
},
{
"post_id": "",
"author": "gxti",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 31, 2013, 03:01:15 am",
"content": "A simple way to think about zener regulators is that you pick a resistor R that will drop just the right number of volts at your maximum output current, and then the zener diode simply \"soaks up\" the current your load is not using. For example. if your input is 5V and your output is 3V and your max current is 1A then you need to drop 2V at max current which means a 2 ohm resistor. No matter how much current the load is drawing, the zener will draw the remainder so that the voltage remains at exactly 3V.This is actually not a terrible way to charge a solar cell but a LDO would be cheap and takes up very little space. You can also use a second LDO to limit the current going into the cap but I bet you won't need it since solar cells have a very high supply impedance. The big advantage over the zener is that it would not be putting out heat once the cap is fully charged."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 31, 2013, 03:10:04 am",
"content": "I'm curious about capacitor voltage ratings too. The cap isn't supposed to be charged to more than 2.7v, but it can handle more than that during charging, correct? I've I put that Zener or buck converter in there before the cap, does that mean that the cap will charge slower? I guess the real question is will the capacitor charge faster at a higher voltage?"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 31, 2013, 03:33:38 am",
"content": "No, the capacitor is rated for a maximum voltage of 2.7 volts. It won't tolerate more during charging.Well, some series of supercapacitors specify that the capacitor will tolerate spikes of up to let's say 2.9-3v or something like that, but that doesn't mean you can subject the capacitor to voltages higher than 2.69v really."
},
{
"post_id": "",
"author": "Jon86",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 31, 2013, 11:34:30 am",
"content": "Quote from: wilheldp on December 31, 2013, 03:10:04 amNo, definitely do not try and put anything over 2.7v into that cap.If you really want to keep the footprint of this circuit small, you could always try a DC-DC module, some of them only need a resistor to set the voltage and they can be as small as you want them to be"
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 31, 2013, 12:20:38 pm",
"content": "A zener or LDO will both dissipate the extra voltage as heat, whereas a buck converter won't (neglecting switching losses etc.)"
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 31, 2013, 10:01:45 pm",
"content": "We'll, i will continue to look for a small buck converter, but I will use a Zener in the meantime. By my calcs, it should only dissipate 66mW (3.3v * 20mA) with the current solar cell, or 165mW with a cell rated for 50mA (thinking about ordering one). That shouldn't generate too much heat, and is well within the limits of the 400mW Zener I ordered.New question...is the resistor required for the Zener to work if I don't need to drop the power dissipated in the Zener?"
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 31, 2013, 10:56:33 pm",
"content": "Quote from: wilheldp on December 31, 2013, 10:01:45 pmIf you start with 6v, and your zener drops 2.7v, you are left with 3.3v. That has to be dropped somewhere to get you to zero volts."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 01, 2014, 03:13:51 am",
"content": "I whacked this circuit in iCircuit on my iPhone while I was sitting around the living room with my family earlier. With just a solar cell (6v, 50mA), a 2.7v Zener and 50F 2.7v cap in parallel with the cell, and two white LEDs on the other side of an open SPST switch, the Zener successfully limited the voltage on the cap to 2.755v. The clamp seemed to work fine (other than the 55mV overshoot). Whenever I tried to put a resistor in series with the supply, the clamp either didn't work, or it significantly retarded the charging of the capacitor."
},
{
"post_id": "",
"author": "mrkev",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 01, 2014, 03:31:40 am",
"content": "Quote from: wilheldp on January 01, 2014, 03:13:51 amWell, what value of the resistor did you use? For 3V and max. 50mA the value should be about 60ohms. But the thing is that solar cells of this kind have already quitte a big Ri..."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 01, 2014, 03:35:42 am",
"content": "I varied the resistor from 1 ohm to 1k. The 47R range seemed to work the best, but still slowed the charging quite a bit. The model for a solar cell includes a series resistance, so I'm wondering if that might be enough to allow the Zener to work."
},
{
"post_id": "",
"author": "mrkev",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "January 01, 2014, 04:25:55 am",
"content": "Quote from: wilheldp on January 01, 2014, 03:35:42 amOf course it will slow the charging process, but i would use at least few (f.e. 15) ohms... Solar panels are not that efficient in the current mode, but it seems to me that you wouldn't mind... If 40% is enough for you, it's easiest sollution..."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 01, 2014, 04:57:37 am",
"content": "I have both Zeners and a buck converter on order right now. I will try both, but the Zener definitely wins in terms of simplicity even though it is far from the most efficient."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 08, 2014, 10:11:51 pm",
"content": "I ordered one of these...http://www.ebay.com/itm/DC-DC-Auto-Boost-Buck-Step-Down-Converter-Module-Solar-Voltage-LM2577-A858-HM-/400629032075?pt=LH_DefaultDomain_0&hash=item5d4759e48bI've tried powering it with up to 7.5V from both the solar panel and the bench power supply (DP832), and no matter what I power it with, I get no voltage on the output. I have tried adjusting the trim pot several turns in each direction, and it has no affect on the output.It is interesting to note that there are quite a few components shown in photos of the board on eBay that do not appear on the board that I received (most obviously the two caps, inductor, and diode right next to the Out+ terminal). Also, there is an unpopulated space for an SMD component next to the trim pot on my board. There is approximately 1k ohms across the unpopulated pads (also doesn't change with movement of the pot).Any thoughts?"
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 08, 2014, 11:44:26 pm",
"content": "Quote from: wilheldp on January 08, 2014, 10:11:51 pmSounds like they sent you an unpopulated board!Take a picture and attach it."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 09, 2014, 12:16:37 am",
"content": "The first image shows the whole board and the second shows the unpopulated pads next to the trim pot. Compare that to the image from the eBay listing that shows the exact same angle as my second photo (looking at the corner containing the Out+ pad)."
},
{
"post_id": "",
"author": "Unknown",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 09, 2014, 05:18:33 am",
"content": "Quote from: wilheldp on January 09, 2014, 12:16:37 amMight be the same angle but it is a completely different board."
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2014, 07:05:25 am",
"content": "Quote from: wilheldp on January 09, 2014, 12:16:37 amWhat you have there is a LM2596 based buck converter (you can read the markings on the chip to confirm), it looks complete at least (erp, maybe not, see next post), but if you bought an LM2577 auto step-up/down converter then that's not what you got.What you have is a step-down (buck) board only, input must be higher than output.You may have to give the pot a lot of turns to get it in range before it starts stepping down, these are 20 turn potentiometers, just dial it all the way in one direction until it clicks, and if still nothing, go in the other direction.These are the typical specs:Input: 4 to 35vOutput: 1.25 to 30vMaximum output power: 12w without heatsink, 20w if you slap a nice heatsink on the bottom of the board (not included)Output current: 2 Amp but remember the power limit above, if using a heatsink you can probably push this to 2.5A or 3A peakRipple: 30mV"
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2014, 07:10:47 am",
"content": "Oh that missing component I didn't notice, looks like it may have been an SMD resistor which has been knocked off (have a look in the mailing bag it came in). If you want to try and get it working, youmayfind it's actually a 0 ohm resistor (aka, jumper), I have a bunch of buck boards which use a 0 Ohm in that position (but the board design is slightly different)."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 09, 2014, 07:37:58 pm",
"content": "See if it's in series with potentiometer. It might be a resistors chosen in such a way so that along with the trimpot the lowest you could go would be 1.25v."
},
{
"post_id": "",
"author": "wilheldp",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "January 11, 2014, 03:14:04 am",
"content": "Thanks for the suggestions, guys. I finally got around to tinkering with this again tonight. It is indeed a LM2596 controller. That isn't necessarily a bad thing, because I don't really need to boost (although it would be nice in low-sunlight conditions). Regardless, I'm going to complain to the eBay seller and see if they'll send me what I actually ordered.I also tried turning the hell out of the pot in both directions. I swear, I turned it at least 100 times in both directions, and it never once clicked or produced a voltage on the output. I'll try to add a low value resistor to the unpopulated pads tomorrow and see if that changes anything. BTW, throughout testing, I had roughly 2.1v on the input to the board.EDIT: I just realized that the minimum input voltage is 3v on the board. But still, there should be some sort of indicator that the trim pot has reached it's upper or lower limit after a certain number of turns, no?"
},
{
"post_id": "",
"author": "sleemanj",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 11, 2014, 04:48:43 am",
"content": "Quote from: wilheldp on January 11, 2014, 03:14:04 amThey usually sort of tick per revolution if you turn past the limit. But you got a multimeter right, measure it, turn it some, measure it again,turn it the other way, measure it againAssume you paid by paypal, if the seller doesn't come to the party, dispute the transaction."
}
] |
2025-10-17T20:10:13.472369
| 30
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-8-to-5v-amplifier-help/
|
2.8 to 5v amplifier HELP - Page 1
|
[
{
"post_id": "",
"author": "fox3d",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 26, 2016, 01:43:11 am",
"content": "Hi guys,I have been following EEV blog from the beginning, but this is my first postcould somebody help me to build 2.8v to 5v amplifier/converter?I have to amplify square wave signal from 2.8 to 5 or 6v. I have tried with arduino but delay was too big even if i used direct port commands.I know it is simple but I cant wrap my head around and i don't want to blow up expensive equipment that's why I'm asking pros hereThanksfox"
},
{
"post_id": "",
"author": "michaeliv",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 26, 2016, 02:05:35 am",
"content": "Some questions to help give better answers:Where is the signal coming from, where is it going to ?What power sources do you have in your system ?Is it a digital signal or analog signal ?What frequency range is the signal around ?"
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 26, 2016, 02:08:58 am",
"content": "Quote from: fox3d on March 26, 2016, 01:43:11 amWelcome to the forum.Level shifting IC or Translator is what you need.Here's a few:http://www.nxp.com/products/discretes-and-logic/logic/level-shifters-translators:MC_29482?cof=0&am=0&tab=Products"
},
{
"post_id": "",
"author": "fox3d",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 26, 2016, 02:33:33 am",
"content": "Signal is digital 20Hz to 90Hz. And it is going also to digital after its amplified so the other device can read it. Power source which is available is 24v 2.2A.But I can use converter 24v to 5v. Or use 24 to drive opamp. I'm kinda scared to use 24v in case of failure. So the 24v don't go to signal input. To me the safest way is to use opto relay. But those have too much of a delay."
},
{
"post_id": "",
"author": "michaeliv",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "March 26, 2016, 03:31:41 am",
"content": "Your 5v thingy might recognize 2.8v as logic high. Check the datasheet if that is the case. If it is, you can connect it directly.I assume that you already have the 5v converter in your system, and won't need to add one just to get this 5v signal.Use the one on the left here :https://pbs.twimg.com/media/A7g86KCCQAAgwds.jpgPerhaps also increase the resistor value to 10k.It's converting 3.3v to 5v, exactly what you want.This will also work, if you prefer MOSFET's :"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "March 26, 2016, 10:46:47 am",
"content": "The frequency is low enough that a simple transistor would work. You've mentioned the delay but not said what's acceptable?Doe it matter if the signal is inverted?If not, the 74HCT04 will do and is very easy yo get hold of.http://www.nxp.com/documents/data_sheet/74HC_HCT04.pdfIf it needs to be non-inverting then you could use two of the 74HCT04's not gates in series or the 74HCT34, which isn't so widely available.https://www.engineering.uiowa.edu/sites/default/files/ees/files/NI/pdfs/00/53/DS005359.pdfThe 74HCT series needs a 5V power supply, which can be obtained from the 24V supply, using the LM7805."
}
] |
2025-10-17T19:21:38.260409
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-9vs-to-3v-12v/
|
2 9Vs to 3V & 12V - Page 1
|
[
{
"post_id": "",
"author": "maxkarlmiller",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 04, 2015, 10:56:03 am",
"content": "Alright, this is my first post on this forum. I have this crappy camera I've made into a night vision camerahttp://www.instructables.com/id/Night-Vision-Camera-1/, but the battery is terrible (for the camera) (2 AAA batteries, so I think 3V, although my volt meter says ~3.5V) and the IR LEDs require 12V. is it possible to get 2 9V batteries to have a 3/3.5V output and a 12V output? If it is, how?"
},
{
"post_id": "",
"author": "Psi",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2015, 11:21:01 am",
"content": "Using 9 volt batteries are usually a bad idea, they are less energy dense and only designed for low current.If you're currently using 2x AAA then 4x AA's are a much better option for more power/capacityHave 2x 2cell in parallel, so the voltage is still ~3VYou could reconfigure the IR led array to run on a lower voltage by having more parallel strings of less leds in series."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2015, 12:36:22 pm",
"content": "The LED light design used in the instructable you referenced isn't very good.TheLEDs usedare 1.28V Vf @100mA and the instructable wires them in parallel in three groups each group with a 220R series resistor. If built as illustrated that gives a mere 4.4mA per LED and probably significant current hogging in a few of them.Redesigning the light to use series strings of 4 individual LEDs each string with its own current limit resistor off two LiPO cells should be a high priority then the camera could be run off a switching 3.3V regulator module from the same battery.Before connecting to the camera, the output voltage should be checked and the regulator may need to be either adjusted if the feedback divider is accessible on its board or one or two Schottky diodes added in series to the output to drop a little voltage and get closer to 3.0VUse a small 2 cell RC LiPO pack and an appropriate balance charger for it."
},
{
"post_id": "",
"author": "maxkarlmiller",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 04, 2015, 01:36:28 pm",
"content": "I didn't use the LEDs used in the instuctable, I used this:http://www.amazon.com/gp/product/B00FZMQ8EA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2015, 03:35:45 pm",
"content": "Start with a battery pack to suite the light and drop it to 3 volts for the camera with a LM2596 adjustable regulator module which are cheap and plentiful on EBAY.If you want maximum rechargable battery life in minimum volume and all with off the shelf modules, you may be better off with a 14.8V 4 cell LiPO pack and balance charger and another LM2596 module to power the light at 12V.Otherwise if you are determined to use primary cells (disposables), 8 x alkaline AA cells could run the light directly for a few bucks from the pound/dollar store or go up to D cells if weigt/size isn't an issue but battery life is."
},
{
"post_id": "",
"author": "maxkarlmiller",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "April 04, 2015, 08:59:18 pm",
"content": "Quote from: Ian.M on April 04, 2015, 03:35:45 pmIs this correct? If it is I'll get 2http://www.amazon.com/Converter-Module-LM2596-Supply-1-23V-30V/dp/B00VC2FQR2. could you also link me to a place where I find out how to use it? I think I'll get a 14.8V LiPo battery pack and use the two voltage regulators to output 3V and 11.8V (I want to have one rechargeable battery for the whole thing.) Is this a good general balance chargerhttp://www.amazon.com/Battery-Balance-Charger-Li-ion-Batteries/dp/B005EF15Q4? Also is this a good batteryhttp://www.amazon.com/Turnigy-5000mAh-4S1P-14-8v-hardcase/dp/B00FXL7XJC? And thanks for all the help"
},
{
"post_id": "",
"author": "JesusCB",
"author_rank": "Contributor",
"is_op": false,
"timestamp": "April 04, 2015, 11:03:19 pm",
"content": "Max, I have been reading a lot about step down converters, I bought one cheap made in china (It will arrive in a month), but the circuit is really easy, and I will make my own regulator with a LM2575 (similar to the LM2596).To adjust the output voltage you turn the little screw in the potentiometer (trimpot). There are other modules with 3 trimpots, with those you can regulate the current and voltage."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2015, 02:12:32 am",
"content": "The reason I suggested pre-built DC-DC converter modules is that some of the chips on the market for these applications can be *EXTREMELY* fussy about layout and choice of inductor, to the point that small changes from the manufacturer's evaluation board layout or substituting an inductor of the same value but different construction can result in greatly reduced output current , or worse, instability. Back in the 90's I scratch-built a switching regulator module to replace a linear regulator that was overheating and it was such a P.I.T.A to get working properly that I vowed never to do that again without a properly designed double sided PCB.It certainly wouldn't have been novice friendly - which I wasn't as my first hacked together switching regulator was back in days when Bob Widlar's µA723 was still in common use."
}
] |
2025-10-17T19:43:36.853044
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-_s-analog-mux-chip-ad9850-dds-at-low-freq_s/
|
2 ?'s - Analog Mux chip & AD9850 DDS at low freq's - Page 1
|
[
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "March 30, 2013, 08:29:27 am",
"content": "2 questions... (1/2 a repost from another thread...but...ya know...)1)For my ASA project, I've settled on an ADG1406 16 channel analog MUX....I think. Want to run it by anybody that is probably more in the know than me...or cares for that matterThis is for the curve tracer project I'm playing around with. Need to switch a select resistor into the D.U.T. part of the circuit. I was going to use a bank of relays. A-takes up too much room, B-don't want to listen to the relays clicking.The signal going into any of the inputs will run anywhere from 100mV to ~12v pk-pk, AC sine wave, roughly 20hz up to 100khz at most. Resistors to be switched will run anywhere from 10ohms up to ~100k. At the higher pk-pk input voltage settings, the lower value resistors will be 'locked out' so the chip doesn't get overloaded with too much current.28 pin TSSOP, dual supply @ +15v/-15v (I'll be running it at +12/-12 at most), fairly low Ron at the switches, low enough for my app.Page 7 of the datasheet (http://www.analog.com/static/imported-files/data_sheets/ADG1406_1407.pdf) shows it'll do 180mA per channel continuous, which is about double what I'll be feeding it, and even then, I'll be feeding a sine wave thru it, so shouldn't be hitting anywhere near the max current limit for any length of time.2)On the subject of those AD9850 DDS modules from ebay. I'm going to assume I don't get one that counterfeit or otherwise \"faulty\"...Google'ing the subject shows a lot of HAMs using these to generate high freq's (e.g. >1Mhz). I'm looking to use one of these modules down near the audio range (e.g. 20-20k).Is the output from these modules pretty clean at low freq's as well?"
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 01, 2013, 08:17:05 pm",
"content": "Quote from: Skimask on March 30, 2013, 08:29:27 amo.O what's wrong with you!QuoteI haven't measured, but the signals look pretty clean on the scope. I'd expect cleaner than they are at MHz frequencies, but maybe you want to add some more filtering; the eBay modules have a 2 (or maybe 3?) pole filter at around 15MHz IIRC. If you're using them for AF it might be worth adding some additional low pass. With a wideband spec of min 63dB SFDR at 1MHz I doubt it's necessary though, depending on your application. If you need cleaner, you probably need to go for a different technology or higher bit-depth DAC."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 02, 2013, 12:15:36 am",
"content": "Quote from: ve7xen on April 01, 2013, 08:17:05 pmJust another mechanical thing to go bad...not that solid state items don't go bad...but...ya know.QuoteThe example app in the datasheet suggests a 5 pole filter at ~40Mhz and looking at the pics of the PCB itself, it looks pretty much like the same thing. This would further suggest that the module would need further filtering at the lower frequencies.I'll find out in a few weeks."
},
{
"post_id": "",
"author": "Smokey",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 02, 2013, 12:53:24 am",
"content": "I don't know if this is the same module you have, but it looks like the one I got off ebay at least. There isn't much going on with that board."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 02, 2013, 03:36:59 am",
"content": "Yep, same thing but different.I got the blue PCB, slightly more square-ish, likely the only difference between the 2."
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 02, 2013, 05:38:56 am",
"content": "Quote from: Skimask on April 02, 2013, 12:15:36 amNow that I'm at home and looking at the actual device I think you're right, the datasheet 40MHz filter seems to be what they've implemented.I have taken some quick scope captures at 1KHz for you. All with 1KHz test frequency, 20MHz bandwidth limit switched in, 1Meg unterminated, DC coupled, microcontroller powered off, and a bit of a ratsnest on the breadboard. CH1 is the 'SINA' filtered output from the eBay module, CH2 is the 'SINB' pre-filter output.The FFT is obviously not that useful with an 8-bit scope, but what the hell, you can at least see some of the harmonics. I don't have time to rig it up to a soundcard right now for more useful measurements. I'm curious though, maybe I will get around to it later."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 02, 2013, 05:58:02 am",
"content": "Well, that's a lot better than what I've got now...which is exactly nothingLooks like the bulk of the mess is about 40-50db down from the fundamental. That's plenty good enough for me and should be easy enough to implement a lower freq filter on that output, along with a opamp to shift the signal levels around a bit."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 03, 2013, 05:17:02 am",
"content": "I don't suppose you've got time to post a pic of that same 1Khz wave with only ~1 cycle displayed?"
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2013, 07:18:43 am",
"content": "Sure, I've still got the test setup sitting on the bench (now under a pile of other stuff). All of these are from the filtered output. There's a bit of a glitch just before and after the zero crossing that I didn't catch before on the 'wider' capture. It doesn't occur every cycle, I'm not sure how periodic it is. I've given a close look at a single shot of that as well (20MHz filter off).Not sure how much it matters with this device, but I'm using a much better power supply for it than last time, I think much of the hash on the unfiltered output before was due to the crappy switching supply I was using. On a proper linear bench supply now.Finally while I had this powered up again I figured may as well plug it into the PC, so I did some analysis there too. This is not the best measurement technique, some gator clips strung across the bench to the PC's onboard line in, but it has much better dynamic range than my 'scope and gives a good idea of the harmonic products; the noise floor seems below that of my sound card."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 03, 2013, 10:25:28 am",
"content": "Well, that output is several orders of magnitude cleaner than what I'm using now, even unfiltered and with the glitch.Which makes me wonder about that glitch....Could it be that these modules are so cheap because they're using bugged AD9850 chips that somebody pulled out of a reject bin?Digikey sells that chip for something like $23, whereas this module is only $5 if you get it from the right guy off ebay."
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2013, 06:11:49 pm",
"content": "Definitely a possibility, though it seems odd to me that there would be a large supply of bugged AD9850s on the market these days, as the design is at least 10 years old. I'd expect if there were bugs in the silicon they'd be long fixed by now, though maybe there is some other parameter that Analog sorts for and these are indeed rejects?Either way performance seems not bad at all for the price. I was going to suggest using one of the more modern 14 bit chips that use a lot less power and have much cleaner output, but at $20-30 a piece from any reputable distributor (and close to zero availability on the grey market) it's worth sacrificing to use these cheap modules instead."
},
{
"post_id": "",
"author": "AlphZeta",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "April 03, 2013, 06:23:10 pm",
"content": "Well, you got what you payed forI have read somewhere that these chips might be from rejected batch. Or they were removed from circuit boards and then resold. Either way, I am not surprised that the performance is hit or miss depending on the source of the chip.Anyway, I bought one a while ago and the waveforms weren't as clean as the pictured. But for what I use it for it is good enough."
},
{
"post_id": "",
"author": "bingo600",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 03, 2013, 08:59:51 pm",
"content": "I have one of these alsoThe ocxo died on it , after a short time.I was feeding it 5v , and it didn't say i shouldn't do that.Maybe the ocxo was 3v3 ??/Bingo"
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2013, 12:17:47 am",
"content": "Quote from: bingo600 on April 03, 2013, 08:59:51 pmWouldn't surprise me. I've been running mine on 5V for some testing, but nothing too long term (few days continuously). AD9850 is only spec'd for a 125MHz clock at 5V though..."
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2013, 06:47:13 am",
"content": "Thinking on this glitch a bit more, I wondered if it's not due to the high impedance of the test circuit and the switching of the adjacent square wave outputs. Low and behold, this is exactly the case. Adjusting the comparator input pot moves the glithces around, and adjusting it to its maximum (it will never trigger) removes them completely.Given the performance measured seems in line with the 1MHz performance specs in the datasheet, I'd say these are either real, or good enough fakes. I don't have a spec-an to test them at RF frequencies of course, so perhaps they falter there..."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 04, 2013, 07:13:27 am",
"content": "And still, at $5 a piece, can't beat it with a stick...Well, you could...but..."
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 04, 2013, 08:15:10 am",
"content": "I redid the frequency domain measurement with a better sound card to post on my blog. This is an emu 1212m, and with this FFT configuration and the input shorted at the end of the cable I used, the noise floor is flat at -130dB except for a -120dB spur somewhere around 30kHz. It's not much different, but confirms it's the output of the module and not the POS onboard sound we're measuring:"
},
{
"post_id": "",
"author": "ve7xen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 05, 2013, 05:44:34 am",
"content": "I learned one more thing today - the AD9850 can't tolerate 15V on Vcc! Oops. Glad it wasn't a project of mine hooked up at the time I madethatstupid mistake."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 05, 2013, 12:34:14 pm",
"content": "At least at ~$5 a piece, not much of a loss."
},
{
"post_id": "",
"author": "Skimask",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "April 18, 2013, 05:33:35 am",
"content": "Finally got around to playing with the cheap AD9850 DDS module from ebay.Works just as good as I thought it would...easy to program, output is a LOT better than what I was using (5 bit DAC output from a PIC...didn't expect a lot from that anyway).The glitch mentioned earlier...I saw that glitch when plugged into the SINA output, but not on SINB. (Using a Tek 2246ModA 'scope)For $4.91USD, I'm happy enough...EDIT: Also, did some rudimentary checking with the 'scope and some figuring...If my math and 'scope reading is right, the -3db point on the SINA output is around 6.42Mhz."
}
] |
2025-10-17T20:23:34.075313
| 20
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-a-5v-single-battery/
|
Delete Delete Delete - Page 1
|
[
{
"post_id": "",
"author": "The_Almighty_Bacon_Lord",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 24, 2016, 10:00:11 pm",
"content": "Delete Delete Delete"
},
{
"post_id": "",
"author": "michaeliv",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 25, 2016, 12:19:58 am",
"content": "Converter:http://www.ebay.ca/itm/-/281291753628Or find a similar, more powerful one.As for if you can drain that much without damaging it it depends on the battery. You need to draw ~3A from it, it should be fine with most cells. Every battery comes with a 'C' rating, Multiply capacity by C to get max current draw. Ex 2200mah * 1.5C = 3.3A max draw."
},
{
"post_id": "",
"author": "michaeliv",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 25, 2016, 01:09:14 am",
"content": "Oulps, you actually want a complete USB charger module that would both charge the LI-ion when supplied with 5v and output 5v when working on batteries ?The link I provided only does the latter half ( it outputs 5v when supplied with input voltage from the battery ).Simply connect the battery to the input, adjust the potentiometer so the output shows 5v, and proceed to draw 2A @ 5v.If you want a complete solution the cheapest way to go is to re-use the internals from this (It claims to output 2A) :http://www.ebay.ca/itm/-/331643918661http://www.ebay.ca/itm/-/401045504413"
},
{
"post_id": "",
"author": "michaeliv",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 25, 2016, 04:08:32 am",
"content": "I assume that \"LiPo\" is a typo since I haven't seen a 18650 LiPo cell, only LiIon.You can use the first link too, even though it uses 4 batteries they are wired in parallel so it's the same as 1 single cell."
}
] |
2025-10-17T19:23:55.851609
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-adc-integration-questions-(serial-communication-and-crystal-oscillator)/
|
2 ADC Integration Questions (Serial communication and crystal oscillator) - Page 1
|
[
{
"post_id": "",
"author": "SethGI",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 27, 2016, 07:24:28 pm",
"content": "Hi,I'm designing a board to input four audio signals, amplify them, and run them through an ADC. I have two newbie questions about this. This is the first real board I've designed (I've designed simple arduino shields before) but I'm a high school student with no real electrical engineering training.1) The chip (ADS1274 by TI) uses SPI for communication. (Frame-sync also available, but I'm using SPI. Everything I've done with SPI in the past has had four pins, SCLK, MISO, MOSI, and SS. This chip doesn't quite. It has DOUT pins as the MISO, and SCLK pin, no MOSI (doesn't matter, probably just means it's a read-only device). But, it doesn't have a SS pin at all. I can't figure out how to use an SPI device that doesn't have an SS pin. There's a DRDY pin that, by their diagrams, seems to send the same signals as the master SS pin usually would. But, since the ADS1274 is obviously a slave device, this isn't helpful. What do I do? Can I just use it without SS???2) An even more newbie question. The ADS1274 requires a CLK input (no surprise). I just don't know how to wire it up to a device like this. I have embedded crystals on to an ATMega chip before which has two clk-related pins, but the ADS1274 only has one CLK input. How do I connect it?Thanks for putting up with my dumb questions!-Seth"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "August 27, 2016, 07:38:15 pm",
"content": "1) no idea this may be a bit of an exotic device.2) the clock comes from the SPI interface on the MCU, it is internally generated, nothing to do with crystals it's just a square wave. It hase to come from the mater in order to keep things syncronised."
},
{
"post_id": "",
"author": "SethGI",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 27, 2016, 08:11:43 pm",
"content": "Quote from: Simon on August 27, 2016, 07:38:15 pmOk...Quote from: Simon on August 27, 2016, 07:38:15 pmSorry, I should have been more clear. This isn't the SCLK, it's the completely unrelated CLK input for the chip. It does require a crystal oscillator, or some other sort of square wave input."
},
{
"post_id": "",
"author": "JPortici",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 27, 2016, 08:36:19 pm",
"content": "typing as i'm looking through the datasheet...this might help you shred some light. it seems like it uses some kind of semi-spi-semi-i2s protocol, like framed spi on several dspics (that don't have proper i2s)http://www.microchip.com/forums/m610484.aspxbasically, sck gives the clock, MISO contantly carries data from the ADC to the master and the frame pulse decided where the beginning ison page 7 of the datasheet, FSYNC pin: Frame-Sync protocol: frame clock input; SPI protocol: data ready output.which means what i said in frame sync mode. in spi mode it means that you have four/eight new data bytes and you should retreive them ASAP (an irq pin to the master).for the clock you might use the clock output of your microcontroller, properly divided so it doesn't exceed max clock rate of the ADCquestion time: why this part? cirrus logic adcs/codecs are easier to use than this one"
},
{
"post_id": "",
"author": "SethGI",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "August 27, 2016, 09:22:34 pm",
"content": "Quote from: JPortici on August 27, 2016, 08:36:19 pmThanks. To answer your question first, I didn't look to much into the cirrus logic ones. I didn't see any reason that this part would be particularly hard to use, except for this communication bit, which I knew I would be able to work out. This part offers good expandability, is very precise, and guarantees simultaneous sampling which is essential for my application. I just checked out a few cirrus audio datasheets and they all talk about how to synchronize the serial outputs of the chip... but with no guarantee about the synchronization of each sample on all four channels. I am using this to calculate the phase shift of high-frequency audio signals, so synchronous sampling is pretty important it may be overkill, but I don't have a problem with that.Anyways, thanks for your answer. It makes sense. I guess worst case is this won't be all that plug-and-play and it might take some work to get this sample.Thanks again for the advice, and I'll definitely take some time to reconsider my part choice."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 27, 2016, 11:05:06 pm",
"content": "Look at the timing diagram on page 8. DRDY' goes low to tell the master it's time to get with the program and start shifting bits. The master now has to shift in 24 bits at a rate between 100 kHz and 27 MHz. However, you need to shift in all 4 channels at the same time so you aren't going to be able to use the SPI gadget of a uC.See the brief discussion of SPI on page 30.I know you said that using SPI would be easy but it seems to me like you're going to have to bit-bang the SCK and read/store 4 data pins at some fairly high rate.I think I would be spending a lot of quality time with the datasheet:http://www.ti.com/lit/ds/symlink/ads1274.pdfAnd, yes, you need to provide a clock. See Table 6, page 27 and note that, for SPI, you can't use the very highest frequency options.I would be paying very careful attention to those few paragraphs re: the clock. Particularly the bit about the 50 Ohm series resistor. And the bit about using a crystal oscillator. Note that it doesn't say just a crystal; they want a canned oscillator."
},
{
"post_id": "",
"author": "JPortici",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 28, 2016, 06:28:03 am",
"content": "Quote from: rstofer on August 27, 2016, 11:05:06 pmi *think* that if he keeps the distances very small he should be able to provide the clock directly by an MCU clock-out pin. It'll have to be < 27 MHz to keep vdd over 2 volts.... but hell i think he can read too.it might be easier to deal with only one low jitter clock circuitalso the SPI can be set up so the ADC sends the data separated per channel on four ports.. or cascade them and sends all through data port 1.. i2s like, but depending on the throughput you need you might need to choose a chip with multiple SPI or bit bang it (in assembly/plain C, of course. or you wouldn't have throughput problems anyway.)"
}
] |
2025-10-17T19:12:58.372567
| 7
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-audio-channels-to-3-5mm-jack/
|
2 audio channels to 3.5mm jack - Page 1
|
[
{
"post_id": "",
"author": "vladio",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 20, 2023, 07:31:44 pm",
"content": "I have a newer Samsung tv in the bedroom that has no headphone connector or bluetooth. I tried an optical converter but I believe there's some type of DRP that mutes the audio on certain apps (Discovery+, Vudu...). Thinking there was only one speaker I bought a switched 3.5mm headphone jack and, yesterday, tried to install it. Upon opening the TV I realized there's 2 speakers, both on separate channels. I tried to tie both grounds into the ground on the switched jack but got heavy static. Just wondering if this is possible.Thanks for your time!"
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 20, 2023, 07:55:09 pm",
"content": "The speakers are probably driven by bridged amplifiers - the + side is driven normally, the - side is driven by an inverted signal, not grounded. This doubles available voltage swing (alternatively: reduces required supply voltage) and enables operation without negative supply. It's a common trick to simplify the power supply of the TV or other device at the cost of more complex amplifier electronics, which are still very inexpensive and probably integrated fully in one chip.This precludes connecting the negative terminals together.To get external audio output, you would need to intercept the signal at the input to the amplifier chip. Further amplification (or at least unity gain buffering) may prove required to drive relatively heavy loads like headphones.editAlternatively, \"balanced\" headphones with separate negative connections to each channel could be used. This is an audiophool gimmick available on some high-end headphones, or it could be DIYd on cheaper ones - the cables often have separate grounds, only connected at the plug.A speaker amp may still end up producing too high volume and/or noise for comfortable headphone use."
},
{
"post_id": "",
"author": "macboy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 20, 2023, 08:25:06 pm",
"content": "I suspect the optical converter didn't work because the TV was trying to send Dolby Digital over the optical S/PDIF connection, when the program being played provides such. This is perfectly valid, and is accepted by any A/V Receiver made in the last 25 or so years with S/PDIF inputs. A simple DAC can only accept uncompressed stereo PCM audio, not Dolby Digital or DTS encoded. There should be a setting in the TV sound menu to output only PCM or Stereo or something similar. Definitely don't choose \"5.1\" or \"surround\" or \"best available\", etc. The TV will automatically decode DD or DTS material into stereo PCM for the DAC."
},
{
"post_id": "",
"author": "vladio",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 21, 2023, 05:25:33 pm",
"content": "Quote from: magic on November 20, 2023, 07:55:09 pmThanks, Magic! I appreciate your explanation!Quote from: macboy on November 20, 2023, 08:25:06 pmThanks, macboy! I did check last night and it was set to PCM, Dolby was greyed out. I didn't have the DAC plugged when I tried, I'll try again tonight with optical plugged in."
},
{
"post_id": "",
"author": "EPAIII",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 21, 2023, 07:13:29 pm",
"content": "They do make four pin, 3.5mm telephone plugs and jacks. Just be sure you mount it with insulation from the chassis or any other ground inside the set. And you will have to do your own headphone wiring. It will be a special set of headphones just for that TV.But then, the speakers will be on while you are using the headphones. That is usually not what is wanted. Another way to do this would be to use two of the telephone jacks with switched normals. One jack for the left channel and the other for the right. There would be no connectionsto the sleeve terminals. Move the speaker wires to the tip and ring contacts in the jacks and the normals would go to the speakers. Be sure to preserve polarity on the speaker wires as you move them. That way the speakers are silent when using headphones."
},
{
"post_id": "",
"author": "Buriedcode",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 21, 2023, 08:00:02 pm",
"content": "What kind of ocnnector do these speakers out have? Is it just a stereo 3.5mm?Another option would be a differential amplifier - taking balanced output of the speakers to single ended, with an opamp per channel, so both outputs are referenced to a common ground - meaning you can plug in your headphones.But there are caveats:1) You would need a ground reference for these balanced outputs - that is you would need L+, L-andGND (and the same for the right channel), thats why I asked about stereo jacks, simply using L+ and L- doesn't provide a ground reference so would require a transformer (decent audio transformers are expensive and more hassle than they are worth).2) The opamp would have to be able to drive headphones - so 50-80mA output, or you would have to follow the differential-to-single ended circuit with an actual headphone amp. High drive opamps are common so might as well just use one.3) It'll need power, which is just another hassle. I did something similar for a neighbours TV and used the USB connector for 5V for the amp (and a TS922 dual opamp for the headphone amp).So ultimately, probably a lot of hassle, but its a solution, albeit a complicated one."
},
{
"post_id": "",
"author": "Thunderer",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "November 21, 2023, 10:18:49 pm",
"content": "As already pointed out, the newer TVs have class-D amplifiers, so the outputs are bridged, no common point from one channel to the other.A simple solution is below. I do not know about the quality of the circuit. Most likely it will kill any trace of damping factor for the amplifiers, so not a good solution for direct connection for headphones (you will need a buffer amplifier). But, it is good if you feed the signal to an amplifier, its input impedance will not play an important role.But, the most elegant solution is something like INA2137 :https://www.ti.com/lit/ds/symlink/ina2137.pdf?ts=1700605262564&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FINA2137, plus a buffer for direct connection of headphones."
},
{
"post_id": "",
"author": "magic",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 22, 2023, 10:35:31 am",
"content": "Not only output impedance increases, but also \"ground\" impedance does and hence you would see increased crosstalk between channels.And if you add buffering, you might as well pick up the signal from before the power amplifier chip. The only downside is that you need to find it on the PCB, it's no longer a matter of just tapping into cables."
},
{
"post_id": "",
"author": "vladio",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "November 28, 2023, 03:53:04 pm",
"content": "I really appreciate the help, thanks everyone!I did some playing around and was able to get audio through the DAC I bought.Macboy's suggestion helped. I had to cycle the tv off/on after the optical was plugged in to get where I could turn off Dolby.Thanks again all!"
}
] |
2025-10-17T16:44:37.251112
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-cell-lithium-charger-ic-handsolderable-(8-4volt)/
|
2 cell lithium charger IC handsolderable (8.4volt) - Page 1
|
[
{
"post_id": "",
"author": "lk",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "October 25, 2013, 09:14:06 am",
"content": "Greetings,I'm on the lookout for a 2-cell lithium charger IC, i was using the mcp73864, but i did not realize until it was too late that it had been EOLed, so now i'm looking for something to replace it, i have spend time on the parametric searches in digikey and mouser, it does not really work for me.I'm looking for something that can charge with 0.5A to 1A, something like the tp4056 but for 2 cells, and it has to be hand solderable, with leads, i need the leads, to be able to probe reliable. And something that does not cost an arm and a legA switching regulator would also be ok.http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Prototyping/TP4056.pdfmcp73684 (it says highly advanced, but i guess not advanced enough to get trashed)http://ww1.microchip.com/downloads/en/DeviceDoc/21893F.pdfDoes anyone have a favorite charger IC that would fit these requirements-lk"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 29, 2013, 06:58:31 pm",
"content": "There you go:http://www.linear.com/product/LTC1731-8.4http://www.linear.com/product/LT1510"
}
] |
2025-10-17T20:14:09.228144
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-ch-voltmeter-with-different-grounds/
|
2 ch voltmeter with different grounds - Page 1
|
[
{
"post_id": "",
"author": "franciscoPT",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 02, 2021, 06:17:43 pm",
"content": "Hi guys, im building a power supply with 2 independent channels 0-30v 0-5A, i will have the measures on 20x4 lcd, to do that i need to measure both voltages and currents on the same microcontroller (i will use atmega328p because i have 3 at home without using it), the microcontroller circuit will be powered by 1 channel of the supply, my trasnformer is rated for 6,5A on each channel because i will make power supply max at 5A, 1,5 its more than enough for microcontroller +2 lcd, my problem its 1 channel will share ground with microcontroller, but the other doesnt, its any way to read the voltage on isolated way such like optocoupler?"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 02, 2021, 07:18:00 pm",
"content": "Probably the easiest option would be an isolated SPI ADC for the second channel, however this would require four optocouplers + your choice of ADC chip. If you use another ATmega328P for the second channel you could use their UARTs for serial communications to transfer the readings via two optocouplers.Otherwise, its possible to subtract out the common mode component of the measurement using an OPAMP + precision resistor network configured as a differential amplifier, but the common mode range is limited by design and you may have difficulty designing it to work with inputs up to 50V outside the rails."
},
{
"post_id": "",
"author": "Ice-Tea",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 02, 2021, 07:49:37 pm",
"content": "Another option is to use an ADUM (or comparable) isolator including power to do the SPI ADC.Another option is to do Analog -> PWM -> opto -> PWM -> analog (or directly in the micro if that's possible)"
},
{
"post_id": "",
"author": "franciscoPT",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 02, 2021, 08:34:33 pm",
"content": "yeh i was thinking in analog to pwm than opto. it seems the easiest solution to me for i will consider the other options."
},
{
"post_id": "",
"author": "S. Petrukhin",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2021, 12:34:25 pm",
"content": "I would make all the channels equally in the executive part, and the control part and the display by a separate device with its own power supply. There are a lot of isolation options, in addition to those listed earlier, look at the analog optocoupler, there are good examples of its use in the datasheet:https://lcsc.com/product-detail/Optocouplers_AVAGO-Broadcom-Avago-HCNR200-500E_C23785.html"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2021, 02:04:35 pm",
"content": "Quote from: franciscoPT on February 02, 2021, 08:34:33 pmEspecially with only positive readings, the old style voltage to frequency converter and than an optocoupler is an alternative. An ADC with serial interface is also an option.There are analog Ok and also isolation amplifiers, but thes tend to be relative expensive of not very accurate. So it depends on eht resolution needed and also the supply available."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2021, 02:56:12 pm",
"content": "I agree ADUM are a good choice as a drop in solution. NVE isoloop deviceshttps://www.nve.com/webstore/catalog/index.php?cPath=30are easier on your pocket and you can buy direct from NVEs webshop. These devices are often overlooked they but are very handy. Have a look at the full product range. GMR, brilliant!Opto solutions can get unexpectedly expensive and bulky in comparison with digital isolators.Look forward to seeing picture of your finished PSU."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2021, 02:56:45 pm",
"content": "But OTT?"
},
{
"post_id": "",
"author": "Doctorandus_P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 08, 2021, 03:54:21 pm",
"content": "Don't. Really just don't.Instead just design a single channel power supply (Including PCB etc) and then build two of them.It will need some extra components, each will have it's own microcontroller and some other things, but those components are cheap. You will also save time because the resulting PCB's are simpler, smaller and cheaper.The microcontrollers can communicate with each other over some isolated channel. UART + Optocouplers is a simple example. I2C or SPI can also be used, but UART is the simplest.Also: If you have a communication protocol to set and request values, then adding a separate project for the interface is also an option. (Possibly even in a separate box and connected with a cable or even RF)."
}
] |
2025-10-17T17:33:58.841590
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-channel-function-genawg-external-trigger-setup/
|
2-Channel function gen/AWG external trigger setup - Page 1
|
[
{
"post_id": "",
"author": "armandine2",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "June 12, 2023, 10:35:38 am",
"content": "w2aew#281: Bipolar Transistor Switching Time Measurementfrom 11:501st channel to generate a pulse from zero volts to a positive level, that I could adjust right here, and, then I’m also using that to trigger the second channel, which is creating a negative pulse That negative pulse is going into the add input on the back of the generator and adding into this waveform and I have it set up so that it’s delayed by this pulse width.So, I’m essentially creating this one pulse that’s triggering a second pulse that’s delayed that creates the negative pulse on channel two where I can adjust the negative drive level that’s occurring after the input pulseSo, by adding those two together I can essentially create this waveform that goes from zero to an adjustable positive to an adjustable negative and back to zero.w2aew's description seems ok to me - followable - but the screenshots, at least for channel 2, I don't understand.any thoughts?"
},
{
"post_id": "",
"author": "Old Printer",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 12, 2023, 01:08:26 pm",
"content": "Have you asked Alan (w2aew)? He is quite approachable and very helpful."
}
] |
2025-10-17T16:53:25.459999
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-channel-power-supply/
|
2 Channel power supply - Page 1
|
[
{
"post_id": "",
"author": "DzAnej",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 19, 2017, 11:54:50 am",
"content": "Hi there,I'm working on a 2 Channel power supply using a transformer with 2X 25V/5A outputs. Next, i would need a supply (5V) for the regulation circuit (microcontroller(s)).Now, because i have 2 channels - how do I measure the voltages on the both outputs without clamping all the grounds together? For now I was testing using an instrumentional amplifier but with that I had to put the grounds together to make it work...For now I thought one way of doing it - Each channel would use its own supply to power the measurment circuit and then send it digitally to the main controller via an optocoupler - that way the 3 grounds (2 channels and main controller) are isolated.Is there a better way than this and how is this done in commercial multiple channel power supplies?"
},
{
"post_id": "",
"author": "Brumby",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 19, 2017, 12:03:53 pm",
"content": "Two meters.These days, they are cheap enough."
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 19, 2017, 02:04:48 pm",
"content": "Yes, they are cheap:http://www.ebay.com/itm/DC-100V-10A-Voltmeter-Ammeter-Blue-Red-LED-Dual-Digital-Volt-Amp-Meter-Gauge/162237038985"
},
{
"post_id": "",
"author": "DzAnej",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "February 19, 2017, 02:40:24 pm",
"content": "Well, I forgot to mention, the supply will be programmable... There will be one display showing preset and actual voltage/current..."
},
{
"post_id": "",
"author": "Cliff Matthews",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "February 19, 2017, 07:02:13 pm",
"content": "You mentioned \"one display\" so the MCU running that can run the side powering it. As for having the other side isolated and yet controlled by the same MCU, that'll likely require high-speed optical circuitry (shifting out and latching DAC data along with getting ADC data back to the MCU on the other side). That may be a stretch for this beginners forum.*Edit - Skip the separate 5v supply, since 7805's can do it fine (and plan for 12 or 24v to run beefy output relays too).Q - Have you considered a slaved, display-less MCU to efficiently run the other side?(You'd still need to opto-exchange command, display and relay data, but the throughput rate wouldn't be so high."
}
] |
2025-10-17T19:02:38.492422
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-channel-relay-to-cut-both-live-and-neutral-ac-line/
|
2 channel relay to cut both LIVE and NEUTRAL AC line? - Page 1
|
[
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 16, 2021, 05:44:24 pm",
"content": "hi guys,First fo all apologies for posting Fritzing \"schematic\" i know a lot of people hate it, but needed something sketched fast as a proof of concept.Basically, my question is simple, i am building a \"power ON/OFF\" module for custom built 3D printer, so the concept would go like this:Rasberry Pi runs on separate power supply, momentary switch is connected to raspberry pi GPIO3 (pin 5) and GND, with a simple script, shorting these two will power ON or OFF the RPi.Once RPi is booted it would trigger GPIO signal to then trigger the relay and allow AC current to go to Meanwell 24V PSU. When shutting down, pushbutton is pressed again and while RPi is shutting down it sends the signal to relays again, cutting off the AC power to printer components.Now, this all works and is clear but what i wanted to do is to cut both LIVE and NEUTRAL line, instead of just one, so my question is:Can i use 2 channel relay (2 relays) to separately cut LIVE line with one and NEUTRAL line with the second relay. Is this OK?Many thanks for any help in advance,Alek"
},
{
"post_id": "",
"author": "fordem",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "December 16, 2021, 05:45:41 pm",
"content": "A two pole relay will do what you want."
},
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 16, 2021, 06:55:39 pm",
"content": "many thnaks but can i use a 2 channel relay? is that safe to use?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 16, 2021, 08:59:24 pm",
"content": "Quote from: elcrni on December 16, 2021, 06:55:39 pmWhat do you mean by two channel relay?The only safe way to do this is with a double pole relay.There needs to be adequate creepage and clearances between the DC and mains."
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 16, 2021, 09:26:29 pm",
"content": "Quote from: elcrni on December 16, 2021, 05:44:24 pmYes, but why? You can use a two-pole (DPST) relay just as easily.https://www.mouser.com/ProductDetail/Panasonic-Industrial-Devices/DSP2A-DC5V?qs=UO%2Fx91QLkSAKSTb%252BBH4SDQ%3D%3D"
},
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 16, 2021, 09:28:41 pm",
"content": "i mean this, image attached. i need 5v control voltage while all 2 pole relays are 24+v, as far as i found. many thanks"
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 16, 2021, 10:10:47 pm",
"content": "Quotemaybe,but its safer ,and part of the uks wiring rules, to have both poles to be broken by the same actuator.Quotetry dpdt instead of double pole,theirs 1000's of em out there,for examplehttps://uk.rs-online.com/web/p/non-latching-relays/1762768"
},
{
"post_id": "",
"author": "SL4P",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 07:59:07 am",
"content": "Reply #3excludes a LOT of ebay / chinese hobby modules.They aren’t designed or manufactured to *any* safety standards for mains voltage isolation.The individual relays may be ok, but the assembly / pcb is rarely compliant to any recognised safety regulations."
},
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 17, 2021, 09:05:35 am",
"content": "many thanks everyone!i would prefer DIN rail mount relay or at lest one with screw terminals and current rating of at least 10A, and of course trigger 5V. seems not easy to find, but also i am not really into relays so any advice about possible specific model would be highly appreciated. thanks, Alek"
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 09:14:28 am",
"content": "Please reconsider working with mains. It is really lethally dangerous, so you really need to know what you are doing.A complete certified brand-name module would be safest, but cost is high. But that's the cost you pay for safety.Chinese PCB modules off Ebay are not usually safe for mains, even if the relays used in them are."
},
{
"post_id": "",
"author": "david77",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 09:40:59 am",
"content": "Do NOT use two single pole relais to switch your load. That could lead to a dangerous situation!If the relay in the neutral wire for some reason does not switch on, but the one in the live (Phase) line does switch on your load will not work. But it will have a live wire attached to it. One might assume the power is off and touch the live wire, which is dangerous.Bitte halte dich von Netzspannung fern, wenn du dir nicht sicher bist, wie man SICHER damit umgeht."
},
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 17, 2021, 10:53:23 am",
"content": "Many thanks everyone for your concern and help.I have been working with mains on hobby level for the past 20 years, electronics in general, but i always ask question when dealing with mains to stay within safety standards, thus this relay question.I have issues finding 2 pole relay with current rating of 10A and control voltage up to 5V, with screw terminals so any specific recommendation would be great.I do not have a problem with 20-50 EUR relay as long as i am on a safe side.I have to agree, ebay/hobby relay modules are not to be trusted, i have used them for tests/concept designs for low power LED light bulbs and sometimes for low current DC.Many thanks,Alek"
},
{
"post_id": "",
"author": "Kjelt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 11:08:11 am",
"content": "5V -> That is because for mains switching you want some real fast force to pull the relay in, preventing arcing.That means in professional applications you mostly see 12V and 24V relays for mains power switching.I would recommend using at least 12V, you can then use a fet or transistor or ic (uln2803a) to switch the 12/24V relay.Further I agree with the above posters for mains switching preferably do not use pcb relays that are open, preferably use a din relais or socket that is isolated and wires with ferrules."
},
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 17, 2021, 11:29:55 am",
"content": "Quote from: Kjelt on December 17, 2021, 11:08:11 amThat makes sense. I can easily implement 5V FET to switch 12/24V relay, the only downside is i would need another DC source for switching the relay.So in this case i would have AC directly connected to 5V Meanwell PSU for RPi and another PSU 12/24V for triggering the relay, everything else would be disconnected, OR i could use single 12V PSU, step down to 5V for RPI and use 12V for relay.All my ferrules and connections are isolated for both AC and DC, i tend to be very cautious about that.So, this one should do:https://www.conrad.at/de/p/finder-22-22-9-012-4000-industrierelais-nennspannung-12-v-dc-schaltstrom-max-20-a-2-schliesser-1-st-506058.htmlMany thanks again for all your help."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 12:43:21 pm",
"content": "5v coil-yepmains rated-yep10A minimum switching capacity-yepscrew terminals-yepreputal brand whos products wont burn the house down?- yepDin rail mountable-be surprised if it ainthttps://www.bpx.co.uk/store/product/lc1d12al"
},
{
"post_id": "",
"author": "rpiloverbd",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 01:11:26 pm",
"content": "'2-channel' relays are for driving two AC loads. Suppose, you want to drive to lightbulbs or one bulb and one fan. Then you will use two channel relays. Your requirement can be fulfilled by DPST relays that many have suggested here."
},
{
"post_id": "",
"author": "CaptDon",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 02:13:33 pm",
"content": "I am not sure if they make a DPST SSR (solid state relay) but if they do it may help you. Most SSR's operate from 3-30vdc at around 10ma. You should be able to drive it directly. They are commonly 240vac capable and many easily do 10a or more. A double pole mechanical relay will insure both sides on or both sides off 'unless one contact welds' which can happen with highly reactive loads, and a double pole SSR would insure both sides on or both sides off unless the internal device failed 'blown SCR or triac' which could also happen. Design for safety but anticipate failures."
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 02:25:36 pm",
"content": "Actually, all this safety talk about needing double pole relays in this thread is just BS.You just do not assume a plugged-in device is potential-free, never, ever. Whether it has single pole switch - completely normal in any consumer device with a plug, typical example would be desk light - double pole switch, single pole relay, double pole relay, or two separate single pole relays, SSR or nothing at all, is utterly irrelevant. Fuse can be blown, and that always disconnects only one of the lines. Half of the countries use nonpolarized plugs so you don't know which one.Even a massive contactor rated for 1000VAC could be accidentally driven on by firmware during servicing, which is why both wires will be disconnected by physically unplugging the device before servicing it. You just can't assume a device that seems non-operational is free of dangerous voltages and start working on it, that is a recipe for disaster."
},
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 17, 2021, 02:50:55 pm",
"content": "Thanks everyone!Ok, so perhaps a bit of further clarification:1. My AC entry is high quality/reputable one with filtering, physical switch and dual glass fuse2. I NEVER EVER work on anything while connected to mains, physically disconnect the cable and then work on things. So the fact that relay can froze/stuck or anything else is irrelevant as its not my main safety barrier.The whole point of this relay is daily printer shut down, perhaps sometimes once a week or so, when i am not using it, so i dont have to flip the main AC entry switch behind the printer every time i want to shut it down. Also, need a soft RPi shut down and then disconnect SSR that controls the heated bed and main board of the printer from mains, with this new relay.This relay is NOT my safety barrier or failsafe, its should serve as a switch to disconnect mains when printer is not in use, and yes, since mains plugs are non polar in EU, disconnecting just one line is not an option as the other line can always be live or neutral, depending on how the plug is plugged.I would also be happy to find SSR with dual pole if possible, but any other reputable/reliable would do.now looking at this one as an option:https://www.conrad.at/de/p/finder-58-32-9-012-0050-relaisbaustein-nennspannung-12-v-dc-schaltstrom-max-10-a-2-wechsler-1-st-1217734.htmlMany thanks for all your help.Alek"
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 03:15:20 pm",
"content": "SSRs are not that great. They have significant leakage current and dissipate more power than a physical relay due to 2-3V voltage drop in TRIAC. Use SSRs for heaters you want to PWM at significantly high frequency (many times every minute), where mechanical relay would wear out.I would use just a normal DPST (or DPDT) relay because they are not much more expensive than SPST/SPDT relays, one from a reputable manufacturer, with proper mains ratings (10A 250VAC for example), then make sure the PCB includes proper creepage/clearance distances. Not going deep into legislation and different standards, generally a 8-10mm distance on bare PCB, or maybe 4-5mm if you add a routed cutout (physical gap on the PCB material), is more than enough. This is the distance between the mains contants and the control side."
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 17, 2021, 03:38:54 pm",
"content": "Quote from: elcrni on December 17, 2021, 02:50:55 pmMany EU non-polarized devices do use double-pole switches to interrupt both lines, but I don't really see why you would need to for your application. But since it is easy enough to do, I suppose you may as well do it the way you want to.What you need is available, just a suitable DPST or DPDT model that meets your specs. They're readily available. As far as mounting options, just use a plug-in relay and get the appropriate socket for it.https://www.mouser.com/ProductDetail/TE-Connectivity/KUP-11D15-5?qs=WGv6JurbshcsYMj0X1dPJQ%3D%3DAsSiwastajasays, I wouldn't bother with SSRs. Especially cheap ones."
},
{
"post_id": "",
"author": "elcrni",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "December 17, 2021, 03:54:20 pm",
"content": "Awesome, this is really helpful guys, thank you!I did not know about \"contactors\" and whats the difference compared to relays...I have found one triggered with 12V:https://www.conrad.at/de/p/finder-22-34-0-012-4640-schuetz-2-schliesser-2-oeffner-12-v-dc-12-v-ac-25-a-1-st-504725.htmlI think i will go with this one.Another new thing learned! :-)"
}
] |
2025-10-17T17:18:08.146477
| 22
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-clocks-from-one-oscillator/
|
2 clocks from one oscillator. - Page 1
|
[
{
"post_id": "",
"author": "DaSkippy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 31, 2019, 03:54:07 am",
"content": "Hey everyone, I have a question regarding clock generation.Description of the problem:In the SNES (yes, the game console) there are currently 2 clocks, one for CPU and one for the APU, which are both highly unstable and varies a lot, for the purpose of emulation, these clocks are 21477272Hz and 24607104Hz respectfully. In our community we try to validate emulators with real hardware by syncing controller inputs and verify that the end result is the same, on the NES this isn't a problem, since there is only one clock, but for the snes it's a huge problem.The greatest common divider between these clocks is 8Hz, which is a bad thing, since you will need to divide and multiply weirdly. And a small diversion initially will result in a huge difference afterwards, we can live with a certain difference between the original clock, but it's more important that the clocks stay in syncNow the question we have is, what would be the best way to get these clocks, and keep them in sync? Would it be best to divide.a 10MHz reference to 1Hz, and start multiplying? And what would be the best method to multiply the signals, since the clock will be I the 24ish MHz range, and each multiplication stage needs to add the same delay, and then at the end we would need to multiply one clock probably by 1 a certain amount of times to keep in sync."
},
{
"post_id": "",
"author": "fourfathom",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 31, 2019, 05:57:19 am",
"content": "Look at the Si5351, an extremely inexpensive and incredibly flexible triple-output clock generator. Put a cheap crystal on it and get two fractional-resolution PLLs driving three fractional divider outputs. Sub-Hz frequency resolution and output range from 8KHz to 150MHz.Datasheet:https://www.silabs.com/documents/public/data-sheets/Si5351-B.pdfA cheap eval board with this chip and an xtal:https://learn.adafruit.com/adafruit-si5351-clock-generator-breakout"
},
{
"post_id": "",
"author": "DaSkippy",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 31, 2019, 08:41:50 am",
"content": "Thanks, this chip seems to be what I need! I will order the eval board from Adafruit."
},
{
"post_id": "",
"author": "awallin",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 31, 2019, 03:24:44 pm",
"content": "FWIW the first number is an exact (6x) multiple of some (by now) slightly obscure NTSC analog TV frequency of 3.579545 MHz. Crystals on that frequency should be available.one could now guess that the second one could be related through multiply/divide also to NTSC, or to PAL (europe?) or to some Japanese analog TV frequency..."
},
{
"post_id": "",
"author": "awallin",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 31, 2019, 03:45:48 pm",
"content": "This page talks about the audio chiphttps://en.wikipedia.org/wiki/Super_Nintendo_Entertainment_System#Technical_specificationsmentions a clock of 24.576 MHz, which is 750-times the usual watch quartz-crystal of 32768 Hz. (or 24-times 1.024 MHz)was that what you meant by APU?"
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2019, 10:20:58 pm",
"content": "you can do it with si5351, it allows to produce two or three different clocks synced from a single PLL, or from two PLL.You can use this cheap module:https://www.adafruit.com/product/2045https://www.aliexpress.com/item/32817431908.htmlHere is also more cheap module, also works ok:https://www.aliexpress.com/item/32972854971.htmlOriginal (blue pcb) module has a better quality pcb and more precise xtal oscillator with error about 200 Hz. Chinese clone with magenta pcb has a little worse pcb quality and xtal with error about 2-3 kHz. But both versions works ok.With XTAL = 25 MHz, you can get 21 MHz with a little fraction part and exact 24 MHz value:21'477'272 Hz = actual 21'477'272.000005688844389483886704 Hz24'607'104 Hz = actual 24'607'104 HzIt can be done by setting PLL = 900.000000 MHz: a=36, b=0, c=1.And use the following multisynth parameters for CLK0 and CLK1 channels:- CLK0 = 21'477'272 Hz: a = 41, b = 60725, c = 67117- CLK1 = 24'607'104 Hz: a = 36, b = 36834, c = 64081Here is a code example:Code:// PLL = XTAL * [36+(0/1)] = 900'000'000 MHzstruct si5351_pll_info pi = { 36, 0, 1 };si5351_set_pll(SI5351_PLLA, &pi);si5351_pll_reset(SI5351_PLLA);// CLK0 = 21'477'272 Hz// a = 41, b = 60725, c = 67117// Actual freq = PLL / [a+(b/c)] = 21'477'272.000005688844389483886704 Hzstruct si5351_msx_info mi0 = { 41, 60725, 67117, SI5351_OUTPUT_CLK_DIV_1, false };si5351_set_msx(SI5351_CLK0, &mi0);si5351_output_control(SI5351_CLK0,SI5351_PLLA,SI5351_DRIVE_8MA,SI5351_CLK_SRC_MS,true, false, false);// CLK1 = 24'607'104 Hz// a = 36, b = 36834, c = 64081// Actual freq = PLL / [a+(b/c)] = 24'607'104 Hzstruct si5351_msx_info mi1 = { 36, 36834, 64081, SI5351_OUTPUT_CLK_DIV_1, false };si5351_set_msx(SI5351_CLK1, &mi1);si5351_output_control(SI5351_CLK1,SI5351_PLLA,SI5351_DRIVE_8MA,SI5351_CLK_SRC_MS,true, false, false);si5351_output_enable(SI5351_CLK0, true);si5351_output_enable(SI5351_CLK1, true);Here is a functions:Code:void si5351_set_pll(enum si5351_pll pll, struct si5351_pll_info* pi){uint32_t p1;uint32_t p2;uint32_t p3;ASSERT( pi->a >= 15 && pi->a <= 90 ); // mult = 15..90ASSERT( pi->b <= 0xFFFFF ); // 20-bit limitASSERT( pi->c <= 0xFFFFF ); // 20-bit limitASSERT( pi->c > 0 ); // avoid divide by zero// p1[17:0] = 128 * a + floor( 128 * b / c ) - 512// p2[19:0] = 128 * b - c * floor( 128 * b / c)// p3[19:0] = cif (pi->b == 0){p1 = 128 * pi->a - 512;p2 = 0;p3 = pi->c;}else{uint32_t frac = (128 * pi->b) / pi->c;p1 = 128 * pi->a + frac - 512;p2 = 128 * pi->b - pi->c * frac;p3 = pi->c;}si5351_write_pll(pll, p1, p2, p3);}void si5351_set_msx(enum si5351_clock output, struct si5351_msx_info* mi){uint32_t p1;uint32_t p2;uint32_t p3;ASSERT( mi->a >= 4 ); // min 4ASSERT( mi->a <= 1800 ); // max 900ASSERT( mi->b <= 0xFFFFF ); // 20-bit limitASSERT( mi->c <= 0xFFFFF ); // 20-bit limitASSERT( mi->c > 0 ); // avoid divide by zeroASSERT( (mi->b == 0 && mi->a >= 4 && mi->a <= 6) ||((mi->a + mi->b / mi->c) >= 6 && (mi->a + mi->b / mi->c) <= 1800) );// P1[17:0] = 128 * a + floor( 128 * b / c ) - 512// P2[19:0] = 128 * b - c * floor( 128 * b / c )// P3[19:0] = cif (mi->b == 0){p1 = 128 * mi->a - 512;p2 = 0;p3 = mi->c;}else{uint32_t frac = (128 * mi->b) / mi->c;p1 = 128 * mi->a + frac - 512;p2 = 128 * mi->b - mi->c * frac;p3 = mi->c;}si5351_write_msx(output, p1, p2, p3, mi->rdiv, mi->divby4);}void si5351_write_pll(enum si5351_pll pll, uint32_t p1, uint32_t p2, uint32_t p3){uint8_t params ={(p3 & 0x0000FF00) >> 8,(p3 & 0x000000FF),(p1 & 0x00030000) >> 16,(p1 & 0x0000FF00) >> 8,(p1 & 0x000000FF),((p3 & 0x000F0000) >> 12) | ((p2 & 0x000F0000) >> 16),(p2 & 0x0000FF00) >> 8,(p2 & 0x000000FF),};switch (pll){case SI5351_PLLA:si5351_write_bulk(SI5351_PLLA_PARAMETERS, params, 8);break;case SI5351_PLLB:si5351_write_bulk(SI5351_PLLB_PARAMETERS, params, 8);break;}}void si5351_write_msx(enum si5351_clock output, uint32_t p1, uint32_t p2, uint32_t p3, uint8_t rdiv, bool divby4){uint8_t params ={(p3 & 0x0000FF00) >> 8,(p3 & 0x000000FF),((p1 & 0x00030000) >> 16) | ((rdiv & 7) << 4) | (divby4 ? 0x0C : 0x00),(p1 & 0x0000FF00) >> 8,(p1 & 0x000000FF),((p3 & 0x000F0000) >> 12) | ((p2 & 0x000F0000) >> 16),(p2 & 0x0000FF00) >> 8,(p2 & 0x000000FF),};switch (output){case SI5351_CLK0:si5351_write_bulk(SI5351_CLK0_PARAMETERS, params, 8);break;case SI5351_CLK1:si5351_write_bulk(SI5351_CLK1_PARAMETERS, params, 8);break;case SI5351_CLK2:si5351_write_bulk(SI5351_CLK2_PARAMETERS, params, 8);break;}}void si5351_output_control(enum si5351_clock clk,enum si5351_pll pll,enum si5351_drive drive,enum si5351_clock_source source,bool isPowerUp,bool isInvert,bool isInteger){uint8_t reg_val = 0;if (isPowerUp)reg_val &= ~SI5351_CLK_POWERDOWN;elsereg_val |= SI5351_CLK_POWERDOWN;if (isInteger)reg_val |= SI5351_CLK_INTEGER_MODE;elsereg_val &= ~SI5351_CLK_INTEGER_MODE;if (pll == SI5351_PLLA)reg_val &= ~SI5351_CLK_PLL_SELECT;elsereg_val |= SI5351_CLK_PLL_SELECT;if (isInvert)reg_val |= SI5351_CLK_INVERT;elsereg_val &= ~SI5351_CLK_INVERT;// set input clock sourcereg_val &= ~SI5351_CLK_INPUT_MASK;switch(source){case SI5351_CLK_SRC_XTAL:reg_val |= SI5351_CLK_INPUT_XTAL;break;case SI5351_CLK_SRC_CLKIN:reg_val |= SI5351_CLK_INPUT_CLKIN;break;case SI5351_CLK_SRC_MS0:reg_val |= SI5351_CLK_INPUT_MULTISYNTH_0_4;break;case SI5351_CLK_SRC_MS:reg_val |= SI5351_CLK_INPUT_MULTISYNTH_N;break;}// set drive Drive Strengthreg_val &= ~SI5351_CLK_DRIVE_STRENGTH_MASK;switch(drive){case SI5351_DRIVE_2MA:reg_val |= 0x00;break;case SI5351_DRIVE_4MA:reg_val |= 0x01;break;case SI5351_DRIVE_6MA:reg_val |= 0x02;break;case SI5351_DRIVE_8MA:reg_val |= 0x03;break;}si5351_write(SI5351_CLK0_CTRL + (uint8_t)clk, reg_val);}void si5351_output_enable(enum si5351_clock clk, bool enable){uint8_t reg_val = si5351_read(SI5351_OUTPUT_ENABLE_CTRL);if(enable){reg_val &= ~(1<<(uint8_t)clk);}else{reg_val |= (1<<(uint8_t)clk);}si5351_write(SI5351_OUTPUT_ENABLE_CTRL, reg_val);}void si5351_pll_reset(enum si5351_pll pll){if(pll == SI5351_PLLA){si5351_write(SI5351_PLL_RESET, SI5351_PLL_RESET_A);}else if(pll == SI5351_PLLB){si5351_write(SI5351_PLL_RESET, SI5351_PLL_RESET_B);}}void si5351_write_bulk(uint8_t addr, uint8_t *data, uint16_t length){i2c_write(I2C1, si5351_addr, addr, data, length);}void si5351_read_bulk(uint8_t addr, uint8_t *data, uint16_t length){i2c_read(I2C1, si5351_addr, addr, data, length);}void si5351_write(uint8_t addr, uint8_t data){i2c_write(I2C1, si5351_addr, addr, &data, 1);}uint8_t si5351_read(uint8_t addr){uint8_t data;i2c_read(I2C1, si5351_addr, addr, &data, 1);return data;}some values from header:Code:struct si5351_pll_info{uint32_t a;uint32_t b;uint32_t c;};struct si5351_msx_info{uint32_t a;uint32_t b;uint32_t c;uint8_t rdiv;bool divby4;};enum si5351_clock {SI5351_CLK0, SI5351_CLK1, SI5351_CLK2, SI5351_CLK3,SI5351_CLK4, SI5351_CLK5, SI5351_CLK6, SI5351_CLK7};enum si5351_pll {SI5351_PLLA,SI5351_PLLB};enum si5351_drive {SI5351_DRIVE_2MA,SI5351_DRIVE_4MA,SI5351_DRIVE_6MA,SI5351_DRIVE_8MA};enum si5351_clock_source {SI5351_CLK_SRC_XTAL,SI5351_CLK_SRC_CLKIN,SI5351_CLK_SRC_MS0,SI5351_CLK_SRC_MS};#define SI5351_PLLA_PARAMETERS 26#define SI5351_PLLB_PARAMETERS 34#define SI5351_CLK0_PARAMETERS 42#define SI5351_CLK1_PARAMETERS 50#define SI5351_CLK2_PARAMETERS 58other definitions for header you can find here:https://github.com/etherkit/Si5351Arduino/blob/master/src/si5351.h"
},
{
"post_id": "",
"author": "FenTiger",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "August 01, 2019, 10:33:37 pm",
"content": "Do they need to be that precise?1 / 21477272 ~= 47 parts per billion. Is the frequency really that stable between different units, across a range of temperatures, etc?Would 21.477 MHz be OK?What about 21.5 MHz?Similarly for the other one."
},
{
"post_id": "",
"author": "fourfathom",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 02, 2019, 07:02:18 am",
"content": "Quote from: radiolistener on August 01, 2019, 10:20:58 pmYou got the parentheses mixed up in the comment. The clock out of the PLL will actually be divided by [a + (b / c)]. The code is correct, at least as far as the a, b, c values are concerned.This device can give you rather astounding frequency resolution, since you have the fractional-resolution dividers in both the PLL feedback loop and the clock output path (plus some additional dividers available in the output path). You usually get better spectral purity if you use integer-only PLL divisors, but in many cases this won't matter. Of course the actual frequency accuracy is only as good as the reference crystal accuracy, but sometimes you want accurate frequency differences even if the frequency itself isn't perfectly precise."
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 09, 2019, 03:57:04 am",
"content": "Quote from: fourfathom on August 02, 2019, 07:02:18 amyeah, you're right, I wrote comment when prepared code for message, and didn't noted mistyping. Fixed. The code is tested and works ok"
}
] |
2025-10-17T18:05:41.532095
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-dacs-one-arduino-nano-two-independent-voltages/
|
2 DACS / One Arduino Nano / Two Independent voltages - Page 1
|
[
{
"post_id": "",
"author": "robert_south1978",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 16, 2018, 06:16:03 am",
"content": "Hi All,I want to build a voltage referance test stand. I want to generate 20 diffeferant voltages (0.0 to 3.3 vdc). I have had success with 2 MCP4725 DACs on one Arduino Nano.( I want to try 4 DACS on one NANO. ) I want to be able to connect the DAC Outputs plus to minus as if they are independent supplies ( or batteries shall we say.) As they have common ground,connecting plus to minus will cause a short. Do I Need something like a virtual ground for each DAC Output ? Using Op amps?Thanks for your help !Robert"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 16, 2018, 07:47:19 am",
"content": "You'd need an isolated reference supply for each DAC and you'd need to isolate their I2C interfaces, so their Vout and Vss terminals are fully floating. The alternative idea of summing the voltages using OPAMPs would degrade accuracy even if you use 0.01% precision resistors.However, as the MCP4725 only has a single address pin and you have to order different part numbers to get different high bits for the address, (MCP4725A0for 00x through to MCP4725A3for 11x), and its still somewhat more difficult to isolate an I2C bus cheaply compared to a SPI bus, it may well be preferable to switch to a SPI interface DAC, possibly with an internal reference, as a SPI bus can be cheaply optoisolated and can support large numbers of identical chips as long as you provide individual slave select signals and their SS (/CS) pin tristates their MISO pin when not asserted."
},
{
"post_id": "",
"author": "robert_south1978",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 16, 2018, 08:04:25 am",
"content": "a: You'd need an isolated reference supply for each DAC / I suppose I could use a cheap buck Booster Power supply for each DAC ?b: you'd need to isolate their I2C Interfaces / Again another Buck Booster PS for the NANO ( or other uP ) ?c: As far as I2C addressing, I have found differant mfg of the MCP4725 use differant adresses. So I could use two from AdaFruit, two from other mfg ( thats four* )What do you think ?Thanks for your response !!* Only Limit here is NANO Memory space"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 16, 2018, 08:40:24 am",
"content": "No.A: Cheap buck-boosts typically aren't isolated. You'd need regulated output isolated DC-DC converters, one per DAC, extra filtering on the output of each DC-DC converter to reduce ripple at their switching frequency, and a calibrated precision reference for each DAC.B: You'd need an individual I2C isolator chip (not a simple bus switch) for each DAC. You don't need to isolate the Nano - it doesn't even matter if it shares a ground with your PC via a USB cable as long as the DACs (and any other 'front panel' inputs and outputs on the device) are fully isolated.C: The high bits of the I2C address are encoded in the part number. It doesn't matter who you order them from: If you order a MCP4725A0it will have the same two possible addresses. Of course some suppliers may have ....A1 ....A2 or ....A3 parts in stock which use different addresses. Some suppliers may be too dumb to care and which ....Anvariant you get will be a lottery. Such dumb suppliers are best avoided."
},
{
"post_id": "",
"author": "robert_south1978",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 16, 2018, 12:04:23 pm",
"content": "Hello Mr. Ian M.A: Of course you are right.I have decided to use 20 NANOs each with one DAC . Each NANO/DAC powered by 12v/5v 200ma isolated DC/DC converters.( TracoPower TME 1205S DC/DC-Wandler, Print 12 V/DC 5 V/DC 200 mA 1 W Anzahl )This way I can power all 20 by one 12v DIN Rail Supply.Plus I will have no worries about I2C Signals.You are right about no Name suppliers, I have have many Problems with no Name. Never a Problem with Adafruit !P.S. we are testing fuel cells hence the 20 voltages, to be used during dummy tests.I keep you up to date if you want.Thanks for your help!!Robert"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 16, 2018, 12:44:37 pm",
"content": "How are you planning to control the 20 Nanos?If you just plug them in to USB they'll all share the same ground and USB is *MANY* times harder to isolate than I2C.20 Arduino Pro Mini boards with galvanically isolated RS485 transceivers on the RX and TX pins of their UART interface could work, with either a master one running a keypad and LCD or OLED to control them, or a PC with a USB RS485 interface controlling them."
},
{
"post_id": "",
"author": "robert_south1978",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 17, 2018, 05:45:03 am",
"content": "Since this is a test stand, it will be operated without a PC or USB connections to any NANO.Each NANO will contain the same program, once programmed, NANO will receive isolated 5vdc on the VIN pin.Each NANO/DAC will output a variable voltage with simple up / down buttons that an operator will control.I plan on putting 4 NANOs/DAC on one PCB board, wire wrap the connections, and stack 5 boards, each identical.( note in fuel cell stack all 'CELLS' are connected in series, so Cell 1(-) to Cell 2(+), Cell 2(-) to Cell 3(+), ect ... )We will verify each Voltage Channel of our fuel cell is recording the correct DAC/Voltage and we can use the DAC/Voltage to testour control software to trigger errors / shutdowns when voltage levels are out of range. ( again, during dummy testing, no real fuel cell installed )Thanks again for your comments!P.S´. Once this test stand has completed it's mission, I can disassemble it and reuse all the components."
},
{
"post_id": "",
"author": "HB9EVI",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "July 17, 2018, 03:17:23 pm",
"content": "some thoughts about that project:- there's always an issue about i2c vs spi - if we are talking about galvanic isolation, spi clearly wins; it's easy to achieve with e.g. 6N137 couplers - as DACs I'd go with the MCP4921, the dual DAC MCP4922 I used for a dual channel PSU, each channel isolated. Well, the only limit with spi of course is the chip select. I don't have in mind with AVR the Nano uses, for 4 CS it should last.- maybe no need, but as caveat: even though these DACs are r2r, they are never accurate enough to serve as, what somebody would call a 'voltage reference', they neither reach VSS down to the bottom nor VDD. of course you can calibrate it out to a certain point, but it's not comparable to a real voltage reference."
},
{
"post_id": "",
"author": "robert_south1978",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "July 18, 2018, 07:08:19 am",
"content": "Dear HB9EVIThanks for your comments.I have never tried SPI, I will play with it one of these weekends.You are correct about the percision of the DACS. But the goal of this project is to simulate 20 cell voltages of a fuel cell. To test the wiring of our FuelCell dev. system.So that voltage on DAC 1 causes voltage increase on our system channel 1, and so on.We are developing fuel cell technology and I am writing the control software for the fuel cell system. Also, by adjusting the DAC voltage over/under a control threshold for each channelwill allow me to test my control software reactions. So percision is not too much in focus.Kind Regards, Robert"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "July 18, 2018, 08:56:32 am",
"content": "20 separate Nanos with manual controls is going to be a real PITA to use. Seriously look at including isolated comms to a PC so you can run a script on the PC to set up all the simulated cell voltages before a test run and sequence changes to cell voltages during a run repeatably.Personally, I'm with HB9EVI on this - its easiest to do the isolation between the Arduino and SPI DACs, as then the Arduino can use its standard USB UART interface for PC comms. The 20 SS (/CS) outputs is easy - simply use three 74HC138 3 to 8 line demultiplexors (+ a few inverters for some of the EN inputs) to implement a 5 to 24 line demultiplexor, with SS from the Arduino connected to /EN, then select which DAC you wish to address by outputting a binary number on five I/O pins. The 74HC138 chips could be distributed over your DAC boards - put one on each (five in total), with a 74HC86 quad XOR on each so you could set the board address with a DIP switch."
}
] |
2025-10-17T18:28:59.976831
| 10
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-different-scope-representations-of-the-same-rf-signal/
|
2 different scope representations of the same RF signal - Page 1
|
[
{
"post_id": "",
"author": "kronos",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 05, 2021, 08:26:20 pm",
"content": "Hello,I have a strange phenomenon and I do not know how to explain it.I generate a 125 MHz signal with a Si5351 board. I can view it in the scope (Rigol, 100 MHz) in 2 ways:1) I view it with the x10 probe; I use the spring connector (not the long ground lead) directly at the output SMA connector. I see this image, which is sort of expected: it is not square, because the BW of the scope is not enough.2) I connect a short RG58 coax to the output SMA, and connect it to the scope; the connection is via a T-connector, with a 50 ohm load at the third end. To my surprise, I see this image: much less amplitude, but much better shape.I cannot explain why both are so different in both aspect and amplitude. I do not understand why the signal looks better with the coax, it is even a square wave, though much smaller. It has even a rise time of 1.24 ns. How is this possible in a 100 MHz scope?"
},
{
"post_id": "",
"author": "radiolistener",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 05, 2021, 08:58:38 pm",
"content": "Quote from: kronos on June 05, 2021, 08:26:20 pmsi5351 has pretty fast rise time 1 ns. It means that signal cosists of harmonics about 1 GHz. 1:10 probe cannot handle it, because it has too high input capacitance and too small bandwidth.When you use probe, it just cutoff all harmonics above 50-100 MHz and reduce amplitude for the signal above 50 MHz. And you will see just low frequency components of the signal. This is why it looks more like sine wave.Such behavior is very predictable and common for any probe, because almost all probes have limited bandwidth and cannot handle 1 GHz without significant attenuation.So the only way is to use good coax cable with 50 Ω pass-through dummy load on oscilloscope side.Note: in order to avoid invalid amplitude, you're needs to put 50 Ω pass-through dummy load at oscilloscope connector. si5351 should be connected to coax cable with no load, because it's output is close to 50 Ω (it's about 55-60 Ω)"
},
{
"post_id": "",
"author": "MarkL",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 06, 2021, 03:14:41 pm",
"content": "If I understand correctly, you are using the x10 probe directly on the SMA connector with no 50ohm load on it. With your coax scenario, you are driving a 50ohm load. The amplitude with the x10 probe is more because it is driving less load.If you put a 50ohm terminator or load directly on the SMA connector and then measure the SMA pins with the x10 probe, you should get more comparable results.A scope will have a rolloff in frequency response. It doesn't stop instantly at its rated bandwidth, and most scopes will surpass their rated bandwidth. So you should still see some squaring off of the waveform.You didn't say what scope you're using, but if it's a Rigol DS1054Z upped to 100MHz, testing has shown it to have a bandwidth of around 130MHz."
},
{
"post_id": "",
"author": "kronos",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 06, 2021, 04:01:04 pm",
"content": "Quote from: radiolistener on June 05, 2021, 08:58:38 pmYes, this was my expectation, and indeed the result with the x10 probe seems logical to me.Quote from: radiolistener on June 05, 2021, 08:58:38 pmAnd this is my problem. With the coax, I see a square wave and much less amplitude. Not expected. The scope input has 1Mohm and 13 pF, so that reduces to 13 pF input in parallel with the 50 ohm termination, after the 50 ohm coax.How can the analog front end be able to display a square wave? The 3rd harmonic is at 375 MHz, way above the BW limit. I should see a sine wave, coax or not. It even measures 1.24 ns risetime, this corresponds roughly to a scope BW of 280 MHz, it should not be able to measure this risetime!"
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 06, 2021, 04:25:54 pm",
"content": "You can measure that signal 10 different ways on 5 different 100MHz scopes and you'll get 50 different pictures. There is no 'real' signal because the scope, probes and connections become part of the circuit. A fast (at least 500MHz) scope with a 50R input might give you a better picture, but even that won't be perfect.A hacked Rigol 1054Z has a rather unpredictable response at these frequencies. The measured risetime of a known fast edge will vary quite a bit, from 3.5ns down to below 2ns, depending on the vertical gain (that's a bug, not a feature) and the bandwidth roll off is gradual, so there is still a significant response up to 400MHz or so. There's nothing unusual about what you are seeing but trying to figure out every detail of why it looks that way thinking that you can extract usable information is probably not all that helpful."
},
{
"post_id": "",
"author": "kronos",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 06, 2021, 04:26:42 pm",
"content": "Quote from: MarkL on June 06, 2021, 03:14:41 pmCorrect, yes, x10 probe with no load. Well, the capacitance of the probe is loading the Si5351, isn't it? At 125 MHz, that is 100 ohm.Quote from: MarkL on June 06, 2021, 03:14:41 pmI tried, and this is the result.I do get the same amplitude, yes! It also looks more like a square wave. Not as good as with the coax, though.What is the interpretation? was I seeing the complete amplitude as there was no load at the Si5351? So with 50 ohm load, if its output impedance is 60 ohm, I should see ca. 1.3V, if its output voltage is 3V.Quote from: MarkL on June 06, 2021, 03:14:41 pmIt is a DS1102. Even assuming 130 MHz BW, it should not be able to display a square wave at 125 MHz (the 3rd harmonic is at 375 MHz), and it should not measure below about 2.6 ns risetime. Which it does now also with the x10 probe."
},
{
"post_id": "",
"author": "kronos",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 06, 2021, 04:34:19 pm",
"content": "Quote from: bdunham7 on June 06, 2021, 04:25:54 pmOK, understood. It is a DS1102, not hacked. Still I find it very strange that I can measure a risetime of 1.24 ns. You are right, I was trying to understand what I see, specially as they are very different images. I now found the major source of discrepancy, as measuring with the x10 probe but loading with 50 ohm gives a comparable result. Which I still do not fully understand.What would experts recommend in cases like this? Measuring with the x10 probe or with coax?"
},
{
"post_id": "",
"author": "Tom45",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 06, 2021, 05:10:54 pm",
"content": "Quote from: kronos on June 06, 2021, 04:34:19 pmThe probe has a bandwidth limit of its own. So the overall displayed signal is affected by the combination of the probe's bandwidth and the scope's bandwidth.A higher bandwidth probe would help.Given the output impedance of your signal source, the coax with 50 ohm termination at the scope input would be the best bet. Unless you buy a much higher bandwidth probe. Best would be to get a 50 ohm feedthrough terminator if you don't already have one since the Rigol doesn't have a 50 ohm input option.Or, you can make your own low impedance Z0 probe. See:https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/for links to some articles. With a little bit of work you can make a much faster probe that would be well suited to what you are doing."
},
{
"post_id": "",
"author": "bdunham7",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 06, 2021, 05:12:22 pm",
"content": "Quote from: kronos on June 06, 2021, 04:34:19 pmAFAIK, that is the same scope, just hacked (Full BW enabled) by Rigol for fee. It still lacks predictable over-bandwidth response characteristics--IOW, it turns into garbage rather than rolling off nicely. The displayed rise-time issue depends on the scopes measurement algorithm, the effects of distortion and group/phase delays as well as the possibility that the front end is being overdriven.QuoteUsing a scope with sufficient rated bandwidth to see your signal would be the first thing. Then you have to consider circuit loading from whatever your connection is. If you can have the source connected directly to the scope input, like the Leo Bodnar fast edge device, that works pretty well, although there aren't many cases where you can do that. If your device has a 50R output impedance, then a coax terminated at the scope is probably best. If your source is low impedance but not 50R, then a properly compensated 10M/10X probe may work, but will further limit bandwidth. If your source is high impedance, you need an active probe of some sort or you need to figure out what your circuit loading is going to do to your signal. Circuit loading issues with normal 10X probes start well below 100MHz--at 100MHz, the lowest input impedance passive probe that I have is actually a 10X/500R/1pF Tek 6156 that requires a 50R scope input. There's no easy way out."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 06, 2021, 07:03:36 pm",
"content": "It looks to me like your have the volts/div set to 100mV/div for the probe and 200 mV/div for the coaxial cable. Before assuming a difference in probe response or loading on the source, double check that the oscilloscope response is not changing with volts/div and separately signal amplitude. We know that the Rigol DS1000Z series suffers from problems in this area. An RF stepped attenuator or set of RF attenuators is useful for this.When I compare probe and coaxial cable measurements on my 100 MHz Tektronix 2232 from a much faster edge source, I get practically identical results even with one of those cheap x1/x10 P6100 probes that you can find anywhere."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 06, 2021, 07:23:12 pm",
"content": "you are driving a scope with a signal it is not meant to display properly. Why? the answer to the response of the scope is either a university thesis or you go and use the correct kit."
},
{
"post_id": "",
"author": "David Hess",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 06, 2021, 08:01:46 pm",
"content": "Quote from: Simon on June 06, 2021, 07:23:12 pmBut a better oscilloscope will at least deliver consistent results within its measurement capabilities."
},
{
"post_id": "",
"author": "MarkL",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "June 08, 2021, 02:40:37 pm",
"content": "Quote from: kronos on June 06, 2021, 04:26:42 pmThe Si5351 has a 50 ohm output impedance, so unless the board has some series resistance, you should get closer to 50% when loading it with 50 ohms.The amplitude you're seeing is likely limited by the scope/probe's bandwidth. To see a more accurate amplitude, you could slow down the Si5351 output until the waveform has a well defined flat top and flat bottom (where the amplitude has settled to values measurable with your equipment)."
}
] |
2025-10-17T17:27:30.977340
| 13
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-diodes-in-series-why/
|
2 diodes in series: why ? - Page 1
|
[
{
"post_id": "",
"author": "Nounours18200",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 30, 2019, 09:12:39 am",
"content": "HI,I have read in this topic:https://www.eevblog.com/forum/chat/vd1212-diodes-replacement/that a good replacement for a VD1212 diode is to use 2x1N4148 in series.I apologize for my lack of knowledge, but why a single 1N4148 is not enough ? I do not understand why to connect 2 in serie, because a diode pass or does not pass the current ?Thank you for your explanation..."
},
{
"post_id": "",
"author": "tautech",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2019, 09:22:37 am",
"content": "The Vf required is the clue to why two in series are required."
},
{
"post_id": "",
"author": "bd139",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2019, 09:25:24 am",
"content": "Exactly that.That's the only characteristic required most most cases for these. They are usually used to give two semiconductor junction drops in amp biasing circuits which is conveniently the same as the B-E drops on the PA transistors added together (or near enough).You can also replace them with a BJT and a couple of resistors (or a trimmer) for a precise drop but it's hardly worth the effort in a reasonably well designed circuit. Look up \"Vbe multiplier\"."
},
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2019, 09:59:43 am",
"content": "Quote from: Nounours18200 on September 30, 2019, 09:12:39 amDiodes can have different V-I curves. THe forward voltage (the point in the V-I curve where the diode starts conducting) for the 1N4148 is around 0.65 V whereas the forward voltage for the VD1212 is around 1.3 V. Putting two 1N4148 diodes in series will approximate the V-I curve of a VD1212.The same thing is going on with LEDs -- red, yellow, green, blue LEDs all have different voltage drops ranging from around 2 V to 3.5 V.Update: Here's are some V-I curves for LEDs. Note that the curves start bending at different voltages."
},
{
"post_id": "",
"author": "001",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2019, 06:27:58 pm",
"content": "Quote from: ledtester on September 30, 2019, 09:59:43 amIs it common constant voltages for LEDs? Can I use LED as a zener diode with low capasitance?"
},
{
"post_id": "",
"author": "bd139",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2019, 06:31:07 pm",
"content": "Yeah you can do that. It's quite handy. You can also use LEDs as varactors."
},
{
"post_id": "",
"author": "Someone",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2019, 11:29:48 pm",
"content": "Quote from: bd139 on September 30, 2019, 06:31:07 pmNoting they have a \"bonus\" photodiode effect which can make those uses a little complicated."
},
{
"post_id": "",
"author": "AG6QR",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 30, 2019, 11:46:42 pm",
"content": "Quote from: 001 on September 30, 2019, 06:27:58 pmTo a reasonable approximation, the frequency of light emitted by a LED is related to its Vf in the same way that the frequency of a photon is related to its energy expressed in electron-Volts.The Planck constant allows you to convert from one to the other.Physics is pretty cool."
},
{
"post_id": "",
"author": "ledtester",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 01, 2019, 02:01:32 am",
"content": "Quote from: AG6QR on September 30, 2019, 11:46:42 pmIn researching my answer I came across this SE thread which suggests that Vf is determined more by the resistivity of the materials used in the manufacturing of the LED:https://electronics.stackexchange.com/a/396384/95488Lots of good comments and food for thought there."
},
{
"post_id": "",
"author": "AG6QR",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 01, 2019, 05:24:38 am",
"content": "Quote from: ledtester on October 01, 2019, 02:01:32 amThere are lots of good comments, and a lot of them talk about how Vf is related to the wavelength of the light produced. It's a common undergrad (or even high school) physics experiment to use colored LEDs to measure the approximate value of Planck's constant.https://www.google.com/search?q=led+planck+constant+experimentBut to get an accurate value, you need to determine the threshold voltage that just barely begins to produce light output, as explained in one of the links from the Google search. Here's one of the experimental procedures:https://www.scienceinschool.org/2014/issue28/planck. Others suggest a more crude approach:http://pages.physics.ua.edu/lab10x/ph102/PDF/Plank%27s_Constant_LAB.pdfThe Vf at a nominal current of 20mA or so may be significantly above the threshold voltage, and may be influenced by a number of other factors, including resistivity of materials. Still, even at reasonable working currents, you'll find that the Vf is still related to the wavelength of light produced. Everyone agrees that, at similar light outputs and currents, red LEDs have a lower Vf than green ones, which have a lower Vf than blue ones. Everyone agrees that Vf is related to the bandgap voltage of the doped semiconductors, and that the color produced is also related to the bandgap voltage."
},
{
"post_id": "",
"author": "Nounours18200",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 01, 2019, 02:53:15 pm",
"content": "usefull info !I currently only have 1N4149 : can I use them (in series) instead of 1N4148 ?The datasheet shows that they have the same Vfmax = 1.0A, but i am not totally sure...Thanks for your replies,"
},
{
"post_id": "",
"author": "rfeecs",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 01, 2019, 06:25:41 pm",
"content": "The frequency of light emitted depends on the bandgap. Vf also depends on the bandgap, but also depends on current. As you lower the current, Vf goes down, all the way to zero. So the number for Vf you get is arbitrary, depending on the current you choose to measure it.In these experiments, they choose a current that works out to give approximately the right answer.Here is yet another proposed school experiment that uses a potentially more accurate way to measure bandgap by varying the temperature:https://hal-amu.archives-ouvertes.fr/hal-01266699/document"
}
] |
2025-10-17T18:02:39.431866
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-layer-pcb-ground-and-vcc-plane-question/
|
2 layer PCB ground and VCC plane question - Page 1
|
[
{
"post_id": "",
"author": "djex81",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 17, 2021, 06:01:59 pm",
"content": "Hello all. I'm new here and new to PCB design. I wasn't sure if I should post this here or in the PCB forum... any ways. Through my research I can not seem to find a clear answer to my question. I'm designing a few PCBs for a MIDI controller which will contain a mix of either push buttons (cherry mx switches), LEDs, or rotary encoders. All ICs and power will be on a separate main board. These PCBs will be the the ones the user will interact with and will connect to the main board via ribbon cable.So my question is this. I'm building these on a 2 layer board. Are there any issues with making the top layer the ground plane and the bottom layer VCC and routing all signal traces on the VCC plane? I read that splitting up a ground plane with traces take away the benefits that a solid ground pour gives. Is this the same for a VCC plane? Some say you should not run traces on a VCC plane and some say you can. Some say on a two layer board having both a ground and VCC plane is not a good idea and that there should only be a ground plane ... However in my case having both planes helps keep the PCB small as I only need to route signal traces.I've included my schematic and top and bottom PCB images below. Any guidance or tips would be appreciated."
},
{
"post_id": "",
"author": "Terry Bites",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 17, 2021, 06:38:41 pm",
"content": "With a switch matrix power planes are probably unnecessary unless your scanning them in the Megahertz.So all's well, go etch. Don't connect mounting holes to ground unless you really need to..... am I seeing Vutrax??"
},
{
"post_id": "",
"author": "djex81",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "January 17, 2021, 06:53:07 pm",
"content": "Quote from: Terry Bites on January 17, 2021, 06:38:41 pmI wasn't sure if mounting holes should be connected to ground or not. Thank you for point that out. Yeah I'm using a Teensy 3.6 and it will be scanning in the MHz range. The clock speed runs at 180 MHz which is probably too fast to scan at and so I'm probably going to have to slow it down some.And no not Vutrax. I'm using EasyEDA right now since I'm going to use JLCPCB to print the boards.Quick question though. When would I ever want to connect the mounting holes to ground? I'm assuring only when the boards need to connect to chassis ground?"
}
] |
2025-10-17T17:35:22.588980
| 3
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-layer-pcb-stackup/
|
2-layer PCB "stackup" - Page 1
|
[
{
"post_id": "",
"author": "pope",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 05, 2023, 08:33:48 am",
"content": "Hello,I'm working on a 2-layer (THT) PCB for an analog audio design. Traditionally, the stackup is usually all (or most) traces on the top layer and the ground plane on the bottom leyaer.Is there any specific reason for this? I personally prefer having the groundplane on the top layer and the traces on at the bottom. It just looks more neat to me and it's somehow easier to read the screen printing."
},
{
"post_id": "",
"author": "John Coloccia",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 05, 2023, 12:44:02 pm",
"content": "From a purely practical point of view, having the plane on the side of the board you're soldering to makes it easier to drive heat into the plane and get good joints. Of course you'll still want thermal reliefs, but every little bit helps when you're hand soldering."
},
{
"post_id": "",
"author": "pope",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 05, 2023, 01:27:45 pm",
"content": "Quote from: John Coloccia on October 05, 2023, 12:44:02 pmThanks for the reply.But usually there are islands and the heat is dissipated from both sides of the PCB, no?I have found quite a lot of statements like the following, but nowhere an explanation of why it should be on the bottom.In a two-layer PCB, design rules indicate this plane should be on the bottom layer, with signal traces and electronic parts on the upper layer."
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 05, 2023, 01:29:32 pm",
"content": "Quite obviously it makes no difference, unless you have some super weird special corner case where your PCB has to act as a shield, i.e., the PCB is doubling as one of the walls of the box, then you would want the outside grounded.Quote from: pope on October 05, 2023, 01:27:45 pmAs a rule of thumb, simply ignore all \"advice\" which seemingly makes no sense and comes with no explanation whatsoever. Illogical statements require strong evidence and clear explanations.Besides, I don't think there is common convention. It can be on either side, both styles can be widely seen in use."
},
{
"post_id": "",
"author": "pope",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 05, 2023, 01:54:04 pm",
"content": "The reason I'm asking is because I think that there must be a reasonFor example on the altium site I found the following:EMI/EMC - Placing a ground plane below signals reduces their inductive susceptibility to EMI. In other words, it helps suppress crosstalk from inside the board and noise induced from sources outside the board.Placing a ground plane on the bottom layer of a two-layer PCB provides noise reduction; it reduces the loop area seen by signals.But still, I don't understand why this won't happen if the ground plane is on top. Is it some sort of a requirement from IPC for example?"
},
{
"post_id": "",
"author": "Siwastaja",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 05, 2023, 01:58:25 pm",
"content": "I think it's just a language/communication issue. What they actuallymeanto say is \"the other side\", but they say \"bottom side\" because they arethinkingabout some example case where traces happen to be at top, and fail to communicate that. People talk illogically like that, and especially if you happen to have any mildly autistic traits like many of us do, such implicit assumptions are hard to see.Replace \"bottom\" by \"opposite\" and now the text suddenly starts making sense - they are simply making a point abouthaving a ground plane at all(instead of long ground traces like on a 1-sided PCB)."
},
{
"post_id": "",
"author": "pope",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 05, 2023, 02:06:00 pm",
"content": "OK I see. Thanks Siwastaja"
},
{
"post_id": "",
"author": "sparkydog",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 05, 2023, 09:27:43 pm",
"content": "Personally, I am a fan of traces on the bottom, ground on top, because it makes the traces easier to visually inspect when the board is covered in components.YMMV. 🤷"
},
{
"post_id": "",
"author": "John Coloccia",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2023, 12:02:29 pm",
"content": "Quote from: pope on October 05, 2023, 01:27:45 pmThat's true, but it's still easier to hand solder through hole when you're heating the side of the board with the most copper, thermal relief or not. Easier to get the solder to flow through to the other side.I have a JBC solder station, and a Hakko desolder station, so it's easy for me regardless...But that's the one practical consideration I can think of for a 2 sided PCB."
},
{
"post_id": "",
"author": "pope",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 06, 2023, 12:31:25 pm",
"content": "Quote from: John Coloccia on October 06, 2023, 12:02:29 pmThanks, that's a valid point. Perhaps another argument would be that it's easier to troubleshoot if most traces are on top and the board is attached to the chassis. But, other than these two reasons I can't really see the benefit of having the groundplane on top."
},
{
"post_id": "",
"author": "tooki",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 06, 2023, 01:04:42 pm",
"content": "Quote from: pope on October 06, 2023, 12:31:25 pmPlease fix your quoting. You’ve added your text within it, so we can’t tell what is and isn’t the quoted text and what’s yours."
},
{
"post_id": "",
"author": "pope",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "October 06, 2023, 02:08:52 pm",
"content": "fixed"
}
] |
2025-10-17T16:47:16.632741
| 12
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-leds-wreset/
|
2 LEDs w/reset - Page 1
|
[
{
"post_id": "",
"author": "gilbenl",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 28, 2017, 12:45:49 am",
"content": "I want to make a light that alternates between two colors, A and B, on power cycle:(on>A>off/on>B>off/on>A...)But when power remains off for a few seconds, say 10, it reverts to A on next power cycle:(on>A>off 10s/on>A>off/on>B).Needs to beverysmall. Explain like I'm five."
},
{
"post_id": "",
"author": "SebG",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 28, 2017, 07:37:09 am",
"content": "You can try something like in the image. You can get a small inverting D-Flip Flop like 74LVC1G80GV,125. That would work with a 5V power supply but if you want higher voltages or even AC you might need to build a D-Flipflop from transistors.The circuit tries to keep the D-flipflop powered during the sort power off cycle with the capacitor but the signal to the clock is isolated from the capacitor using a diode. So the clock will pulse high when power is applied and then fall low when disconnected and if the flipflop remains powered by the capacitor and the main switch is pressed again it will toggle the output again. On initial power up the clock pulse can toggle the output so you can add a small filter (debounce) to delay the signal so you get consistent power up value.One light is gated by a P-MOS and is on when the output is low. And the other is gated by a N-MOS and is on when the output is High.The two pull down resistors should be high value like 10k or so."
},
{
"post_id": "",
"author": "gilbenl",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 28, 2017, 04:04:16 pm",
"content": "Thank you-Looks like a promising starting point. I have some CD4013BD ICs somewhere I can dig out and test. It will be a 12V-13.6V circuit (car), but I suppose I could use a zener for the IC."
},
{
"post_id": "",
"author": "SebG",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 28, 2017, 11:21:42 pm",
"content": "if you use a zener diode for the IC the output will not drive the PMOS gate to a high enough voltage to turn it off. (ie the Vgs will not be low enough since Vsource will be 12V) You need to use an open collector driver with a pull up resistor to 12V driving the PMOS. So when the output of the IC is high the PMOS gate is pulled up by the resistor to 12V turning it off and when the IC output is Low the open collector driver pulls it low turning it on."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 28, 2017, 11:28:52 pm",
"content": "If the LEDs only need 10mA or so then there's no need for the MOSFETs. Connect the LEDs and series resistors to the 'Q' output, with one to +V and the other to 0V."
}
] |
2025-10-17T18:55:41.012875
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-lithium-cells-to-12v/
|
2 lithium cells to 12v? - Page 1
|
[
{
"post_id": "",
"author": "k.neo",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 26, 2023, 10:19:22 pm",
"content": "Hello.I have a 12v project I am working on.I wish to use 2 lithium cells to power it, either series or parallel.Is there a circuit that can manage the step up and charging of the cells?18650 or 21700."
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 26, 2023, 10:32:46 pm",
"content": "The one linked below is for two 18650s in parallel. The fine print at the bottom says the 12V version will do 1.2A. One negative for this module is that it doesn't have any way to turn it off except removing the batteries. I think that's a pretty big negative. But it has protection built in, as well as a load sharing circuit which lets you charge the batteries and power the load at the same time.https://www.ebay.com/itm/204252590625"
},
{
"post_id": "",
"author": "BeBuLamar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 26, 2023, 11:36:58 pm",
"content": "Why don't you just use 3 cells and without the converter?"
},
{
"post_id": "",
"author": "k.neo",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "December 27, 2023, 01:39:18 am",
"content": "Using 3 cells could be a valid point.Would need a bms charging circuit for protection, wouldnt I?Any suggestions?The end goal is to power a DC ballast for a 4w to 10w uv tube. I am not sure what wattage to go for yet. The longer the tube the bigger the ligth fixture will be.The ebay suggestion is interesting, maybe a switch could be spliced in."
},
{
"post_id": "",
"author": "BeBuLamar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 27, 2023, 11:29:10 am",
"content": "I would use 3 cells and the charger with BMS would be a separate device."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 27, 2023, 02:16:18 pm",
"content": "What wavelength does the UV tube output? If it's a black light i.e. 350nm to 390nm. then go for LED, which is much more efficient in this wavelength range."
},
{
"post_id": "",
"author": "Peabody",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 27, 2023, 03:21:57 pm",
"content": "What's your charging source voltage?"
},
{
"post_id": "",
"author": "Mechatrommer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 27, 2023, 10:39:53 pm",
"content": "i use this 3 cells cheap circuit in my latest project... just supply with 12V mains adapter source on its output pin, when blackout, its on batteries. its mini UPS... fwiw..https://www.aliexpress.com/item/1005004858806346.htmlhttps://www.ebay.com.my/itm/384308219625https://shopee.com.my/3S-20A-Li-ion-Lithium-18650-Charger-PCB-BMS-Protection-Board-12.6V-Cell-64x20x3.4mm-Module-i.32805005.23637159505"
},
{
"post_id": "",
"author": "p.larner",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 30, 2023, 09:01:35 pm",
"content": "Just a word of warning,not all of the el cheapo ebay bms units have working low voltage cutoff,i built a 6s battery using one of those for my prc-320 radio,then left it on rx to see how long a charge lasted,it killed 3 groups of 18650 cells."
}
] |
2025-10-17T16:43:09.360918
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-motor-usb-stepper-controller-without-messing-around/
|
2 Motor USB Stepper Controller without Messing around - Page 1
|
[
{
"post_id": "",
"author": "Orestecom",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "March 31, 2019, 09:32:19 am",
"content": "Hi everyoneAnyone available for a Paid Project. We Need to control 2 stepper motors (under one AMP each) via USB connected to a Windows PC with our custom application. Polulu and trinamic Offer only 1 or 3 plus axis. And 3+exceeds the budget of 100dollar per Controller.Not an Option ist putting several components together such als 1 arduino 2 Stepper 1 shield 3... 5...2... And each has to be programmed seperately.A Trinamic custom solution would be my FavouriteYou may send me a Line to [email protected] Have a good One"
},
{
"post_id": "",
"author": "ebclr",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "April 01, 2019, 10:28:12 am",
"content": "This can be easily done with arduino somehing like thishttps://pt.aliexpress.com/item/Placa-Controladora-3-GRBL-Laser-Eixo-Stepper-Motor-Driver-USB-Placa-de-Grava-o-A-Laser/32961197563.html?spm=a2g03.search0104.3.52.3b1f6abbQo89uq&transAbTest=ae803_3&ws_ab_test=searchweb0_0%2Csearchweb201602_8_10065_10068_10547_319_10059_10884_317_10548_10887_10696_321_322_10084_453_10083_454_10103_10618_10307_537_536%2Csearchweb201603_16%2CppcSwitch_0&algo_pvid=842fffc0-1623-4596-818f-a63c270447d8&algo_expid=842fffc0-1623-4596-818f-a63c270447d8-7"
}
] |
2025-10-17T18:13:35.001642
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-off-24v-coil-relays-in-parallel-one-back-emf-diode-sufficient/
|
2 off 24V coil relays in parallel. One back EMF diode sufficient? - Page 1
|
[
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 01, 2017, 02:11:02 pm",
"content": "I am building a high power antenna change over box. One big Russian REW-15 relay switches a single aerial between a TX and an RX with a delay time. The other, smaller, 40 Amp 24V automotive relay grounds the RX antenna on TX. I used a hefty one in the hope that if anything went disastrously wrong it had some capacity to short TX output to ground without the relay contacts blowing upThe Russian one has a 1N4007 across the coil, am I right in thinking the smaller one won't need another diode, the interconnecting leads to the two coils in parallel are about 6 inches long. I am running a 180 ohm 1/2 Watt resistor in series with the smaller automotive relay, as held on for long periods it got quite warm. the spec sheets show a minimum pull in voltage of 14.4V The resistor drops the voltage to circa 18V and doesn't seem to get too hot. This smaller relay has a 324 ohm coil. With the dropper resistor the relay coil stays cool. Thanks."
},
{
"post_id": "",
"author": "Benta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2017, 02:13:23 pm",
"content": "One diode is enough, but if the relays really are that massive, you should check if the current carrying capability of a 1N4007 is enough."
},
{
"post_id": "",
"author": "oldway",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2017, 02:32:34 pm",
"content": "Free wheeling diode mustalwaysbe a fast diode....so, choose UF4007, not 1N4007..."
},
{
"post_id": "",
"author": "floobydust",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 01, 2017, 11:43:19 pm",
"content": "A 1N4007 is OK, as it is a fast-on but slow-off (~2-10usec reverse recovery) diode. No drama unless PWM is seen.I've measured peak current with relay back-EMF diodes and it's the about the same as the coil current.Usually relay coil power (heat) is reduced by using a lower holding current, at say 50% voltage after 100msec when the relay pulls in. 50% PWM at around 20kHz is also used.Or use a capacitive-discharge to hit the relays hard with high voltage to switch quickly, then reduced holding voltage after.Typically I get 175mH coil inductance for 30A (85R coil) and I can include a Spice sim if really worried about it."
},
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 06, 2017, 07:53:14 pm",
"content": "Thanks for the great answers and detail, all running AOK and I have learned as well"
},
{
"post_id": "",
"author": "TimFox",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 07, 2017, 09:33:56 pm",
"content": "How much do you pay for these diodes?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 08, 2017, 04:28:11 pm",
"content": "Quote from: TimFox on August 07, 2017, 09:33:56 pmCost might not be the deciding factor. It could be space or just more convenient to have a diode on the PCB and the relays are connected by wires."
},
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "August 08, 2017, 05:02:23 pm",
"content": "Purely technical / academic interest, I merely wanted to know if one was sufficient paralleled across two relay coils"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 09, 2017, 01:35:02 am",
"content": "The diode only needs to handle as much speed and current as the transistor doing the work. Flyback isn't some magical surge, it's merely the continuation of whatever current was flowing when the switch opened.Accordingly, the diode should also be placedat the switch, diverting the current into a stable (locally bypassed) supply.It's not the coil that's making the flyback, it's the switch. The coil is just a reserve of EMF (voltage). It's the switch (and diode, and whatever else in the circuit: resistance, capacitance and all that) that causes the waveform.Tim"
}
] |
2025-10-17T18:51:06.503376
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-ohm-between-vcc-and-ground/
|
2 Ohm Between VCC and Ground - Page 1
|
[
{
"post_id": "",
"author": "fagiano",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 27, 2014, 05:51:11 pm",
"content": "Hi,I've just assembled a board I designed, is all smd that I soldered with solder paste and a hot air gun. I was testing for shorts and I found that ground and VCC are shorted with ~2ohms between them. I have an MCU+crystals a eeprom a regulator and few leds on the board. Is there a way to troubleshoot this? I already desoldered the decoupling cap that had the lowest resistance and it wasn't it. Any tip? or I just go component by component and desolder everything?thank you for your timeciaoAlberto"
},
{
"post_id": "",
"author": "MatCat",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 06:03:44 pm",
"content": "A schematic / pics would be of help."
},
{
"post_id": "",
"author": "electronics man",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 06:05:17 pm",
"content": "check all the solder joints with a magnifying glass."
},
{
"post_id": "",
"author": "fagiano",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 27, 2014, 06:08:50 pm",
"content": "Here's the board"
},
{
"post_id": "",
"author": "zapta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 06:14:58 pm",
"content": "A few shots in the dark1. Have you measured a non populated board?2. What is the resolution of your ohmmeter? Can you see fraction of a ohm? If so, you can track the resistance.3. Apply a low voltage and track using voltmeter and voltage drops.4. Apply a low voltage and examine with a thermal camera."
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 06:15:09 pm",
"content": "Quote from: electronics man on February 27, 2014, 06:05:17 pmYes, visual inspection is maybe the best way. But it is possible, that the board has small errors. Unfortunately that happens sometimes, especially with PRC boards, or cheaper boards in general. If you feel like it, one of the debug mode is freezing the board, and turning it on, the short will heat up the frost. Or you can connect a 5A power supply to your VCC that will show the short also. Both can be destructive."
},
{
"post_id": "",
"author": "fagiano",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 27, 2014, 06:23:48 pm",
"content": "I have an Agilent 1272A DMM, I tracked the lowest resistance to VCC_C3 and I desoldered it, the pads still give the lowest resistance. Could it be a toasted MCU? Maybe I cooked it. Unfortunately I haven't tested the board before assembling(lesson learned!). I wish I had a thermal camera. So, if apply power what should I look for? hottest component?thank youAlberto"
},
{
"post_id": "",
"author": "fagiano",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 27, 2014, 06:37:24 pm",
"content": "I applied 5V to the board, both the regulator and the MCU become really hot. The regulator I assume is because is sucking too much current, I tried up to ~1A, could it be the mcu?Alberto"
},
{
"post_id": "",
"author": "fagiano",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 27, 2014, 06:52:35 pm",
"content": "I removed the MCU, and the short is gone. Does this prove anything?thank you all for your suggestionsAlberto"
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 07:05:17 pm",
"content": "It could be soldering problem, still. If you have a spare MCU, try with that. This time, maybe take care about ESD, if you didn't do it previously. And double check the schematic."
},
{
"post_id": "",
"author": "MatCat",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 07:19:58 pm",
"content": "A microscopic bit of solder can cause such a short and be very difficult to see, I have also had solder paste blob up under chips and you won't really know it until you desolder the chip to see."
},
{
"post_id": "",
"author": "fagiano",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 27, 2014, 08:10:18 pm",
"content": "Ok, I think i found it. I generated the schematic symbol with a script I wrote that reads database files from ST MicroXplorer. There is a bug in the database file, one pin was wrong and I was grounding it instead of connecting it to VCC. Unfortunately I trashed 1 MCU, Argh. Hopefully the rest of the pins are corrent!thank you allciaoAlberto"
},
{
"post_id": "",
"author": "electronics man",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 08:16:50 pm",
"content": "so is the resistance between Vcc and gnd normal now?"
},
{
"post_id": "",
"author": "fagiano",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "February 27, 2014, 08:57:14 pm",
"content": "Yes, I also make the schematic symbols myself but for large components I usually write a script that reads manufacturer documents/files so I don't screw-up. Seems that assuming that all manufacturer files are correct was a mistake.Yes the resistance is now normal.I happened to have a unpopulated pad to VCC(R8) and I fixed the bug with a 0 ohm resistor. I have the board programmed and running!Alberto"
},
{
"post_id": "",
"author": "amyk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 09:41:08 pm",
"content": "Note that although 2 ohms may look really low (and for low power applications it is) in low-voltage high-current circuits it might be perfectly fine - e.g. a typical laptop or desktop CPU will look like a complete short across the power rails."
},
{
"post_id": "",
"author": "HackedFridgeMagnet",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 27, 2014, 09:54:50 pm",
"content": "Maybe first time you turn on the prototype use a current limited supply."
},
{
"post_id": "",
"author": "zapta",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 28, 2014, 12:37:55 am",
"content": "Quote from: fagiano on February 27, 2014, 08:10:18 pmThat's an happy end in my book. You found the problem."
},
{
"post_id": "",
"author": "tszaboo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 28, 2014, 03:12:28 pm",
"content": "Quote from: fagiano on February 27, 2014, 08:57:14 pmglad to help"
}
] |
2025-10-17T20:07:13.422257
| 18
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-phase-full-wave-voltage-multiplier-for-maximum-voltage/
|
2 phase Full Wave Voltage Multiplier for maximum voltage? - Page 1
|
[
{
"post_id": "",
"author": "Deactivated-1",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "May 06, 2020, 07:13:54 am",
"content": "I am building a tube amp and need more B+ from it, it draws about 700mA from the B+ and I need 1kV and the power transformer outputs 400-0-400VACI can't use just a 2 phase rectifier since I intend to use it in class B2, (for experimental purposes) and need about -300V bias (why I need such high bias? long story short: I'm using a cf to drive the output, and because of it, it reduces the -300V to about -100V. also, I have the plate at 8V, I could connect it to ground, but then I couldn't get it into class 2, I'm sure)anyway, I was wondering, can I use a 'Full Wave Voltage Multiplier' circuit to get 2 supplies double the voltage?or is there maybe a better circuit for this?I couldmaybeuse a voltage doubler but I doubt it could handle 700mA."
}
] |
2025-10-17T17:50:36.716803
| 1
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-pin-flasher-relay-circuit-suggestions/
|
2 pin flasher relay circuit suggestions - Page 1
|
[
{
"post_id": "",
"author": "int2str",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 07, 2015, 09:59:01 pm",
"content": "My motorcycle (like many others) has a 2-pin flasher relay to make the turn signals work.Essentially:12V --> SWITCH --> RELAY --> TURN SIGNALS --> GNDThe relay has no other pins. Apparently the actual flashing is often accomplished with a bi-metal strip that disconnects the turn signal temporarily when it's heating up and then closes again etc. This is load dependent and thus falls apart when you switch from incandescent bulbs to LEDs.Now, I know there are multiple \"cheats\" to fix this:1. Add ballast resistors to the LEDs (lame)2. Wire in an \"LED relay\", which usually means it needs a separate ground pin, aka 3 wiresWhat I'm trying to figure out is a way to do this without the 3rd wire.Ideas that came to mind:1. Use a micro controller (ex. ATTiny85) to handle the flashing and use a large enough capacitor to keep the chip running in the \"off\" period. Use a mosfet to control power. I'll have to do the math on this if I can get enough charge in 1s or so \"on\" period to survive a 1s or so \"off\" period.2. Use a 555 timer and again, a large enough capacitor to do the same thing as in 1). Using a 555 makes the circuit more complicated, but it can run at 12V. But gain, need to figure out how to keep it running in the off period.3. Come up with a completely discrete charge + flip/flop? circuit that does this. Problem here is that I would have to de-couple the discharge timing from the load itself. In other words, I'd have to find a way to discharge a capacitor through an arbitrary load while retaining constant timing.I'm strongly leaning 1), but any tips/tricks welcome!Thanks!"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 07, 2015, 10:59:20 pm",
"content": "It's fairly simple, as you guessed, using a 555 timer."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 07, 2015, 11:27:47 pm",
"content": "While that circuit would work with an incandescent bulb load, good luck running a 555 off the couple of volts that will be left after the Vf drop of a string of 5 or 6 Amber LEDs! You'll either need a micropower circuit that that will run off as little as 2V and a boost circuit for the FET gate drive, or a reasonably low value resistor across the LED bulb load."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 12:43:31 am",
"content": "Quote from: Ian.M on November 07, 2015, 11:27:47 pmUse a CMOS version such as the TLC555, TS555, ICM7555 etc. (these draw less power and work down to lower voltages than the traditional NE555) and a MOSFET with a very low threshold voltage (such as the PHD38N02 or FDN337) or a BJT (such as the ZTX690 or ZTX1053) with a high beta to drive the LEDs.https://www.fairchildsemi.com/datasheets/FD/FDN337N.pdfhttp://www.nxp.com/documents/data_sheet/PHD38N02LT.pdfhttp://www.diodes.com/_files/datasheets/ZTX690B.pdfhttp://www.farnell.com/datasheets/1643255.pdfhttp://www.st.com/web/en/resource/technical/document/datasheet/CD00000893.pdfhttp://www.ti.com.cn/cn/lit/ds/symlink/tlc555.pdfhttp://www.st.com/web/en/resource/technical/document/datasheet/CD00000893.pdf"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 02:33:06 am",
"content": "That may do the trick. Better use a Schottky diode for D1 and *DON'T* even *THINK* of fitting it to an old kickstart bike with an AC lighting system!"
},
{
"post_id": "",
"author": "int2str",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 08, 2015, 03:55:42 am",
"content": "Wow, you guys are rockstars!!I was looking for inspiration, not a complete circuit, but that's even better!I'll whip it up and see if I can get it to work!Thanks so much!"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 04:12:06 am",
"content": "Try it on a breadboard on the bench, with the supply set to whatever voltage your bike's electrical system runs at (probably around 14V) with the headlight on full beam at idle, and one of the LED bulbs you want to use. If it craps out on the road, while you are waiting to turn at a busy junction, it could get you killed, and if it doesn't meet your local regs for flash rate etc. it could get you a traffic ticket."
},
{
"post_id": "",
"author": "int2str",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 08, 2015, 04:43:56 am",
"content": "Ian, of courseI've also been riding for 20+ years and a misbehaving turn signal is very far down the list of things that will get me killed on a motorcycle"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 05:04:58 am",
"content": "Once you have a handful of years riding under your belt, the experience you gain doesn't make you much safer due to the other bloody half-blind idiots competing for the same patch of Tarmac. I quit riding anything two wheeled a good many years ago. I *used* to have a couple of mates who didn't quit . . . ."
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 10:51:21 am",
"content": "Personally I ride a motorcycle and don't drive a car (even though I have a licence and can afford to do so) because I feel safer on a bike.I have replaced a bike's indicators with LEDs before. It worked quite well and passed the MOT (for non-UK readers, this is a compulsory annual road worthiness test). I added resistors though and didn't bother with replacing the flasher relay with an electronic one.An electronic flasher should be more reliable and a mechanical one. If you're worried about over voltage transients then connect a 16V zener diode in reverse parallel with the flasher."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 11:42:05 am",
"content": "I've not had a lot to do with bike flashers,but I did look into replacing my car one with a solid state circuit,years ago.It turns out that the bi-metal device is a pretty hard act to follow.If you lose a lamp,the flasher click rate increases audibly,giving you a warning.Trying to do anything like that with Electronic components gets very messy,very quickly.I know most cars use solid state flashers now,but it looks like they've just given up on trying to reproduce the electromechanical device's speed increase with reduced load.Of course,with LEDs the chance of losing a \"lamp\" is very much reduced."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 02:33:19 pm",
"content": "Most cars use an electronic flasher which senses current flow, and flashes faster if there is a blown bulb dropping the load below the expected one of 21W+21W+5W+3W. Newer vehicles with a body control module use a high side switch for the indicator lamps, and do current sensing in the module to indicate a blown bulb on the driver display. The ticking sound is from a small speaker inside the dashboard, fed with a sound file that emulates the relay clicking."
},
{
"post_id": "",
"author": "vk6zgo",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 03:26:48 pm",
"content": "Quote from: SeanB on November 08, 2015, 02:33:19 pmIn other words,a complex circuit to do what a bi-metal switch did!A factory made unitcanbe more complex than the homebrew one I was trying to design 30--odd years ago"
},
{
"post_id": "",
"author": "Seekonk",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 03:44:23 pm",
"content": "I worked on a friends motorcycle after his step brother wire up LED turn signal so they only worked when the motor was off. It was a two wire electronic flasher that worked fine with LED."
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 08, 2015, 03:48:01 pm",
"content": "Car manufacturers also use an ASIC design, which pays for itself over many units as the lamp load is pretty much constant across vehicles. I had to replace a 2 pin flasher, so went to the dealer spares and they gave me a 3 pin one, along with a small wiring loom with a 2 pin connector to fit the original socket and a wire to connect to a specified bolt on the frame as the ground connector. Old bimetal flasher got too expensive to make as it is a mostly hand assembled unit."
}
] |
2025-10-17T19:30:44.151228
| 15
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-pin-header-polarity/
|
2 pin header polarity - Page 1
|
[
{
"post_id": "",
"author": "microbug",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "May 13, 2013, 05:51:06 pm",
"content": "Hi,I'm designing a pcb for my own linear power supply. It uses header connections for the supply input and output. The header connector sockets have a square and a round hole (see attached) - which one is ground and which is V+? I have wired it so that the square is ground for now, but it's very easy to change.Thanks!"
},
{
"post_id": "",
"author": "8086",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 13, 2013, 05:55:29 pm",
"content": "If you're asking if there's a standard, I don't think there is.There is a de-facto standard that the square pad is pin 1, but none that I know of that dictates whether it should be positive or not.I would suggest you just add polarity markings to your silkscreen for reference."
},
{
"post_id": "",
"author": "microbug",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "May 13, 2013, 05:56:25 pm",
"content": "OK, I suspected there wasn't a standard after seeing different orientations on Google Images, but just wanted to make sure. Thanks."
},
{
"post_id": "",
"author": "glatocha",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 01:06:49 am",
"content": "I also don't know if there is any standard, but I have two boards that (I think) are using same connectors for power supply.The boards are from Microchip and Xilinx so maybe following them would not be bad.I can check how they are connected later today."
},
{
"post_id": "",
"author": "Farley",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 02:27:05 am",
"content": "I think that most PCB patterns for electrolytic capacitors use square pads for the positive lead."
},
{
"post_id": "",
"author": "Rufus",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 02:52:39 am",
"content": "Quote from: microbug on May 13, 2013, 05:56:25 pmThey are general purpose 2 pin connectors with no standard use and so no standard pin allocation.If the alternative is tossing a coin then I would make the square pad +ve. A square pad (if there is one) universally indicates pin 1. On a schematic I would by default put pin 1 at the top and it is pretty universal to draw schematics with +ve supply rails at the top."
},
{
"post_id": "",
"author": "Fsck",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 03:23:09 am",
"content": "Hate to point out the obvious but the square one has a + in the middle of it."
},
{
"post_id": "",
"author": "glatocha",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 03:26:14 am",
"content": "It is the orientation point of an object in Eagle. You have is also next to the CAP"
},
{
"post_id": "",
"author": "digsys",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "May 14, 2013, 03:31:14 am",
"content": "I ALWAYS make the pin that has the most Cu area, the GND or 0V. For connectors, caps, LEDs etcI know you can add copper, but that's not the same thing."
},
{
"post_id": "",
"author": "mikes",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 08:13:11 pm",
"content": "An argument for pin 1 being ground is if you had multiple voltages - you would always need ground, so start with that on 1, and put other voltages as you work upward.One handy trick is to use a 3 pin connector. Center pin is V, outer pins are ground. That does two things - it can be plugged in either way without reversing the voltage, and you can wire a ground to one outer pin and shield to the other. For compatibility with that, on a 2 pin connector, pin 1 would be still be ground."
},
{
"post_id": "",
"author": "glatocha",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 08:40:29 pm",
"content": "Quote from: glatocha on May 14, 2013, 01:06:49 amSo I checked. On Xilinx board there is a different connector.On Microchip board connector is same like yours. And the square pin no 1 is used as a +V."
},
{
"post_id": "",
"author": "Short Circuit",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 09:24:39 pm",
"content": "G.Round"
},
{
"post_id": "",
"author": "KJDS",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 10:32:56 pm",
"content": "Best practice poka yoke suggests:-Make sure that if something can be put in place it will work whichever way round it is put in. Therefore use three pins with the outer two as ground.If the above isn't possible make sure it can only be fitted one way round and that the correct way is obvious, therefore use a polarized connector."
},
{
"post_id": "",
"author": "glatocha",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 11:25:52 pm",
"content": "This is the polarized connector what he is using. It can be only one way."
},
{
"post_id": "",
"author": "mikes",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 11:51:31 pm",
"content": "Quote from: glatocha on May 14, 2013, 11:25:52 pmIt's not clear where you came up with that, he simply said \"header connector.\" Basic headers aren't polarized, although some connectors like the Molex KK series are."
},
{
"post_id": "",
"author": "8086",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 14, 2013, 11:52:45 pm",
"content": "Quote from: mikes on May 14, 2013, 11:51:31 pmThe silkscreen. He is right, the footprint is for a polarised connector. Looks like Molex KK."
},
{
"post_id": "",
"author": "mikes",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 15, 2013, 12:13:10 am",
"content": "Quote from: 8086 on May 14, 2013, 11:52:45 pmThat's an assumption, he may have simply chosen an Eagle part which has 2 0.1\" pads. It's not like the silkscreen forces you to stuff a particular part."
},
{
"post_id": "",
"author": "8086",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 15, 2013, 12:28:02 am",
"content": "Quote from: mikes on May 15, 2013, 12:13:10 amI am answering your question regarding where it came from. The footprint is for a molex KK connector."
},
{
"post_id": "",
"author": "hlavac",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 15, 2013, 11:42:57 am",
"content": "For 2 wire connectors where polarity matters and connections have to be easy and quick I have used 3-pin connectors wired as one wire middle pin, second the side pins.It does not matter which side you plug it in."
}
] |
2025-10-17T20:22:17.140895
| 19
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-pin-output-zvs-vs-3-pin-output/
|
2 pin output ZVS vs 3 pin output? - Page 1
|
[
{
"post_id": "",
"author": "owin",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 24, 2023, 08:36:07 am",
"content": "Hello, what's the practical difference between 2 pin output ZVS and a 3 pin output?Generally, 3 pin output is being used as a flyback driver and 2 pin as an induction heater driver. Why would you use a 3 pin over a 2 pin?Does the 3 pin receive feedback to synchronise the frequency to the harmonics of the coil?Thankyou."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 24, 2023, 10:26:03 pm",
"content": "Look, you're approaching this with WAY too much formality.You're lucky if the manufacturer even knows what the board does, or how it works. Frankly they put some parts on a board, and it seems to sell. Whether there's design intent behind that (or just copycat, or a wholly random walk at all), let alone any kind of support or service infrastructure -- irrelevant. It's just a board from Ali (or Amazon, or eBay, or..). It's nothing more and nothing less than the circuit you see in front of you.If I had toguess, assuming that the circuits are the traditional kind, for the traditional meaning of what that is (which, realize, is quite a stretch given the vast space of possible circuits that might be described using these few vague terms -- but given their popularity, this interpretation is still most likely to be correct); I would guess that the three-terminal one -- because it has one inductor rather than two -- is made for centertapped windings ONLY, while the other one can use either arrangement (just leave the CT unconnected).If it means you got (or are about to get) scammed because you bought something you have no idea how to use, or that means you can figure out some use (maybe not the original desired or intended function, even), whatever -- so it is.Tim"
},
{
"post_id": "",
"author": "owin",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "August 25, 2023, 05:16:33 am",
"content": "Yes the 3 pin requires a centre tapped primary, but the question is why? what does a centre tapped primary achieve that isn't done by a straight coil? Is it purely just a design of the oscillator that has no bearing on the final output?"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "August 25, 2023, 06:24:26 am",
"content": "It has one less component."
}
] |
2025-10-17T16:49:27.151180
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-pole-2-way-switch-question/
|
2 pole, 2 way switch question - Page 1
|
[
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 04, 2015, 12:28:02 pm",
"content": "I have 2 server power supplies, 50V at 73 amps each. Outputs are isolated from ground. I want to put them in a cabinet and have a high capacity switch to change their outputs from parallel to series. I want to use a 2 pole, 2 way switch for this, but suitable amperage ones are hard to find. The schematic I will work from is attached. Can I use this Ebay sourced switch, or even cheaper, use two double pole 100 amp mains isolation switches bought separately (for a lot less) with their toggles bridged together and mounted on a common DIN rail, with (and I think I would need to do this...) one mounted upside down??http://www.ebay.ie/itm/CHANGEOVER-SWITCH-GENERATOR-TRANSFER-125-AMP-1-SINGLE-PHASE-DIN-RAIL-COSDIN-/281692272367?hash=item41962af6ef:g:0HwAAOSw9N1Vk9GRThanks!"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 04, 2015, 12:51:56 pm",
"content": "No. Its contacts almost certainly aren't designed to clear a 50VDC high current arc.You need a switch rated for at least 120V 100A DC (120V because it has to clear the arc when the PSUs are in series)Try googling: 100A DC knife switch DPDT"
},
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 04, 2015, 01:03:49 pm",
"content": "Ahh, OK, thanks, but would it be OK if no live switching was done? I cannot foresee a time when i would want to go from series to parallel or vice versa with the supply feeding a load."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 04, 2015, 01:40:12 pm",
"content": "Not OK, but it can carry the current and withstand the voltage. If you are lucky, it might even survive operating under moderate load a few times. However its an electrical fire waiting to happen unless you can rig an interlocked cover that shuts down the PSUs before anyone can access the switch."
},
{
"post_id": "",
"author": "Chris Wilson",
"author_rank": "Super Contributor",
"is_op": true,
"timestamp": "November 04, 2015, 01:58:46 pm",
"content": "OK, got you, thanks for the warning, I'll probably look for a knife switch, but only I will be operating it, and all the big knife switches seem to be in China, much appreciated Ian!Actually they do an enclosed one, I could put a microswitch on the cover and have it run a relay on the input side, I have some BIG relays... Cheers."
}
] |
2025-10-17T19:30:57.438629
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-port-networks/
|
2 port networks - Page 1
|
[
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "January 24, 2017, 08:58:51 pm",
"content": "Well having finished one section of my course i start the next. 2 port networks. I have read a few pages of giberish now. It seems they are explained as purely mathemartical models and with no practical explanations I am totslly lost. The net and youtube seems full of stuff that is as expanded and unhelpful as my course material. does anyone know of any more practical explanations ?"
},
{
"post_id": "",
"author": "Kremmen",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 24, 2017, 09:26:21 pm",
"content": "The thing is that 2 port networks are not supposed to be \"practical\". They are a conceptual model (a black box if you will) to abstract some real process or device.The port model is a formula in linear algebra such that you (often/usually?) model input voltage and current vs output voltage and current. The format is simplyy = Ax where x is the input vector, y is the output vector and A is the transformation matrix.The calculation is done by the usual linear algebra rules y1 = A11*x1 + A12*x2; y2 = A21*x1 + A22*x2There are several different 2 port models that are used depending on the subject topic- Such as the hybrid model used to model e.g. a transistor.Check this page:http://gradestack.com/Analog-Electronic/Transistor-Biasing-and/h-Parameter-Equivalent/19280-3866-36878-study-wtwThere in the middle picture you find all 4 terms of the hybrid 2 port network matrix A (they are the hybrid parameters h11, h12 ...). The physical meaning is somewhat obvious from the picture such as h11 is the port input impedance and h21 is the port current amplification (also identified as hFE in transistor data sheets).Many other 2 port presentations exist but maybe you get the idea from this.P.S. You need to select the variables above such that y1 = Vi, y2 = Io; x1 = Ii, x2 = Vo"
},
{
"post_id": "",
"author": "The Electrician",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 28, 2017, 06:04:36 am",
"content": "This is worth looking at:https://en.wikipedia.org/wiki/Two-port_network"
},
{
"post_id": "",
"author": "Neganur",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "January 28, 2017, 02:16:02 pm",
"content": "circuit simulation is based on those models (e.g. Spice) and some models' usefulness is more appearant than others': (already mentioned) H-parameter, S-parameters etc.They are useful to simplify complex systems, and you will most likely learn to use this as a continuation from circuit analysis courses.Get a good cheat sheet that lists the models and get to know how you can transform from one to the other. With time you'll know the 3-4 most useful ones by heart anyway."
},
{
"post_id": "",
"author": "Brutte",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "January 28, 2017, 02:54:47 pm",
"content": "A: Once you know the equations that govern each independent building blocks, you can understand how a compound connection of those blocks behave by calculating the combined equation. With two port networks this step from block to complete system is elementary (linear algebra, you can train a dog to solve that).B: However a design of a real life project works exactly in the opposite direction: You know the equation of the overall system and now it is time to decompose that to elementary building blocks, pick a soldering iron and make it work.You won't solve task B without deep understanding of task A. Not mentioning that the step from B to A is not unique (not sure how that goes in English, I mean 1:1) as there are many component arrangements that meet same equation."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2017, 03:12:31 pm",
"content": "Yeah, it's a black box method. Would it help to reflect on what it means, practically?Suppose you have a black box with two BNCs. What is it?Plug it into a VNA. This applies RF to one port (i.e., hooked up a 50 ohm amplifier, which transmits at a variable frequency), and measures the power transmitted (to the other port) and reflected (back to the amplifier; a carefully balanced network separates the transmitted and reflected waves).The various frameworks (h, Y, s, ABCD...) are just different ways of expressing the same thing, usually with a purpose in mind. h-parameters are easier to measure at low frequencies, s-parameters at high. Matrix decomposition methods tease apart the different parameters of the system, so they can be more easily worked with (but, this probably doesn't interest you much, because math).Maybe this is way ahead of where you're at (what's a VNA?). Suppose you just probe the box with a multimeter. Suppose it's a resistor network! How can you tell what it is? It could be somecomplicated mess, but all that can be reduced to a few resistors. (To be exact: (N^2 - N) / 2 resistors, for N nodes.) For the two-port box, if you connect the grounds together, it has N = 3, so needs 3 resistors.You have 3 unknowns, so you need to collect at least as many parameters. Note that resistance is a ratio of voltage to current, so you need four parameters (e.g., two voltages and two currents), but only end up with three in the end (one gets eliminated).That's easy to see, because to measure a resistance, you have to applysomevoltage (or current), but the exact amount doesn't matter, as long as it's nonzero: it's a free variable.So, you might apply a voltage between nodes 1 and 2, and measure the resulting current flow, and measure the voltage on nodes 2 and 3. You now have V12, I12 and V23. Lastly, you can short nodes 2-3 and measure the current, to get I23. Now you have a complete set of data.Alternately, you could apply voltage to nodes 2-3 and measure voltage V12, to obtain 3 voltages and 1 current. You can't measure only voltages, or only currents, because then you can't find the resistance.The symmetries at work here, are very similar to those of geometry: you can define a triangle from three sides, or two sides and an angle, or one side and two angles; but not three angles, because then there's no length reference. Learning how the underlying symmetries work, can save you from a lot of trouble manipulating equations you're not otherwise very prepared to work with (like because your eyes glaze over every time you look at it!) -- anywhere you see the wrong combination of numbers being multiplied and divided together, or different amounts being added or subtracted, you can be sure you've made a mistake.Tim"
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2017, 03:53:48 pm",
"content": "I have been wondering why you got to 2 port networks so fast. We didn't do it until much later than DC and AC circuit analysis. Then I tumbled to the idea that they are just taking a more formal approach to Thevenin and Norton equivalent circuits. Making the internals 'active' by modeling a transistor isn't a huge stretch. When I was in school, the idea of 2 port networks didn't come up until filters and transmission lines - I still have the book...I haven't done Chapter 4 of \"Real Analog\" and but I have worked through the first three chapters and the lectures are very good. In the spare time you don't have, why not take a look:https://learn.digilentinc.com/classroom/realanalog/I went through the first 3 chapters when you posted the analysis problem a couple of weeks ago. Good review, expecially the bit about the Super Node.OT: You know, it is common for students to form \"study groups\", hire tutors and ask questions of the TAs (Teacher's Assistants). Your study group just can't all get to Mickey Dees at the same time. Remote learning at its best!"
},
{
"post_id": "",
"author": "Vtile",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2017, 04:32:04 pm",
"content": "Were these the CCVS. VCCS. CCCS. VCVS ? I'm forgotten so much.."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2017, 05:10:13 pm",
"content": "Quote from: Vtile on January 28, 2017, 04:32:04 pmThey are, as they are all forms of dependent sources.It's good that Simon brings up these topics. If I EVER knew the material, it was a very long time ago and the review has been interesting as well as educational.Between these problems and my grandson's Calculus course, I'm getting quite a re-education. I doubt there is any science to the idea but a lot of folks believe that keeping the brain working in old age is a good way to stave off Alzheimer's. So, Simon, keep it up!"
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "January 28, 2017, 07:21:28 pm",
"content": "Quote from: rstofer on January 28, 2017, 03:53:48 pmIt's not until video 1.13 that the instructor gets to VCVS using an Op Amp. The previous videos were strictly Thevenin and Norton, something that you have already covered (I assume).I don't know how far the instructor will get with dependent sources in this series. He implies that the majority of the coverage would come in a future course."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "February 07, 2017, 08:15:55 pm",
"content": "Sorry it's taken me so long to reply.Thank you all for the help and encouragement. I really wish I had a better understanding of maths and was able to remember more of it as at the end of the day everything relies on it. To whoever pointed out that normally the task is to take a system that needs designing and has a known input to output equation and then that needs breaking down into smaller blocks. That is exactly why I wish I had a better grasp of maths and was able to understand it better.I've just had to take a short detour into matrices and using them to solve equations (as if the 1600 pages of this module were not enough already) so I'm now back onto the actual 2 port material."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "February 07, 2017, 08:21:56 pm",
"content": "Quote from: rstofer on January 28, 2017, 03:53:48 pmOh don't worry, my next module is a project. Lord knows what sort of project they expect people to produce having only studied maths some physics and elementary circuit analysis. Perhaps a battery a switch and a light bulb.However in all seriousness I think the project module is supposed to be for people to go away and study something of their own and produce a project. Well if they want they can have 1 of my commercially available brushless fan controllers with full explanation of how it works."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 07, 2017, 08:24:41 pm",
"content": "Congrats on your recent 10k posts, by the way."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "February 07, 2017, 08:25:35 pm",
"content": "Quote from: T3sl4co1l on February 07, 2017, 08:24:41 pmOh wow, I hadn't even noticed. Last time I looked I was just over 9000, or so I thought."
},
{
"post_id": "",
"author": "rstofer",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 07, 2017, 08:29:36 pm",
"content": "Quote from: Simon on February 07, 2017, 08:21:56 pmPost the problem when you get it!"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "February 07, 2017, 08:31:02 pm",
"content": "Well if it's just a case of me coming up with a project then that is much easier. This is the whole conundrum of this course, while I can't memorise and understand the depth maths or do a lot of the elementary circuit analysis I don't have a problem designing a circuit board to accomplish a task and even writing a little C code. Maybe the grade I get for the project can balance out the shit grade I'm going to get on the current module."
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "February 20, 2017, 07:49:35 am",
"content": "Well as it happens yes they want me doing transmission lines, the 2 port networks was to chuck me into that so they got it over with in one lesson out of 4 and except one question the whole assignment to foloow is about transmissions lines."
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 20, 2017, 10:45:02 pm",
"content": "A simple inductor (wound as an air spaced solenoid) is a great component to study/model as a two port network because it is not as simple (in reality) as a pure inductor. You can either model it using lumped components like many people do or you can use transmission line theory to get a better model across a wider frequency range or you can go even further and measure it as a two port network (using a VNA) up to your chosen upper frequency limit.The lumped (LCR) model is the classic inductor model but it falls apart even before you reach resonance. A crude transmission line based model can model it better up past the first resonance but to really capture the inductor as a wideband 'model' the two port model is usually the best providing you just need a small signal (i.e. linear) model of the inductor. The two port model is usually obtained using a VNA that can measure the inductor in a fixture and then the VNA can output the measurement data in s parameter format)"
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 12:00:27 am",
"content": "Quote from: G0HZU on February 20, 2017, 10:45:02 pmFor some in-depth background on the matter, see:http://hamwaves.com/antennas/inductance.htmlThis guy has researched the subject extensively. (Making a detailed RLC model, equivalent to the parameters calculated by the formulas, would be relatively trivial.) I don't suggest reading this in detail -- but skimming over it to see some of the effects at work, and seeing what methods are used to solve them (sometimes theoretical, sometimes empirical), is fascinating.Tim"
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 01:05:57 am",
"content": "Yes, I've seen a lot of that stuff before, but I really wanted to suggest alternative/better methods to model an inductor across a wide frequency range. The lumped models are pretty lame in this respect.There seems to be a lot of research going on by the people in your link(s) but for reasons that totally baffle me they still want to chase the elusive 'self capacitance' to ultimately use in a lumped model. Some of those guys appear to have been into this stuff for decades but I would suggest that even a junior RF engineer would leapfrog that stuff fairly quickly as the lumped model is so limited in frequency range.That's why I suggested Simon looks at a typical 2 port model of an inductor or even a simple tline based model as a practical example to show how these models usually outperform the old school lumped models for wideband design work involving inductors"
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 01:46:24 am",
"content": "A practical example would be a very simple highpass filter. Maybe for use with a scanner receiver where reception below (say 10MHz) may cause overloading. The ideal HPF would be flat from 10MHz up to maybe 1GHz or more to allow it to be used over the full scanner range.But if someone built such a HPF using a big (air) solenoid coil then they would discover that there would be some dips or notches in the response up in the UHF region when tested. These sharp/narrow dips could look like 10-20dB holes in the receiver range and would cause deaf spots. I don't think any of the mainstream research by the chaps who are chasing the ultimate 'inductance/self capacitance/SRF equations' would help much here because these resonance modes are not related to the classic lumped model that they help produce.A two port model of just the inductor will typically give a very good indication of where these dips will appear once the inductor is fitted to the HPF. It would also be able to predict the width and depth of them quite well. Simply use the 2 port model in an RF simulator and draw the complete HPF circuit and then simulate/predict where trouble will happen.A simple transmission line based model would be almost as good, but it won't predict the notch depths or locations as accurately."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 02:03:35 am",
"content": "At least the notches are (usually?) pretty modest. The helical waveguide is dispersive and quite high impedance.Roughly speaking: think of each pair of turns as a parallel pair of transmission lines. The end-to-end impedance is approximately (N-1) times the transmission line impedance of that pair. Nearby pairs of round wire, in air, are in the 100-200 ohm range, so a ten turn inductor can easily be kohms.The first resonant mode is parallel, so the impedance peak is towards infinity (limited by Q; practical cases are in the 10s to 100s of kohms).Subsequent valleys and peaks (they always alternate) have similar ratios above and below the mean impedance. But again, because it's dispersive, because those parallel wires are so intimately linked together, there isn't really a mean impedance, nor do the peaks and valleys come at integer multiples of the first resonant frequency.So... to do an HPF like that, yeah, there may be dips. Even though the dips can be quite significant relative to the mean impedance, it can also be that the mean is so high (~kohms) that it doesn't have much effect (not 10-20dB, but maybe only 2dB or less). That's been my -- rather limited -- experience, but I've not played with enough combinations of coils and sizes, and not over that wide a frequency range (2 decades).Also, ferrite loading can cure a lot of ills: for helical and helicotoroidal* inductors, you only get a couple of modes before the whole thing kind of decays into mush (the equivalent loss resistance of the core dominates over the wave properties of the winding). Ferrite is wonderful stuff..*As in, a helix wound around a toroidal path. A single layer toroid winding. These have a first resonance that's one full wavelength (because of the continuity of magnetic field around the loop), and are also dispersive (non-harmonic). The resonant modes are relevant to any kind of toroidal transformers (including CTs), RFCs and tuning coils. Different winding and shielding designs can be used to short out the resonant modes.The worst off-the-shelf example I know of is the Triad CST-206, which is rated for 100kHz bandwidth, and they mean it: the first resonant mode is at a paltry ~300kHz, so the square wave response is absolute shit for anywhere near rated bandwidth. The response also varies with where the primary loop is placed: if it's at right angles to the secondary pins, the ringing is minimal. So it varies with placement...Tim"
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 02:39:19 am",
"content": "QuoteYou certainly talk a good gameHowever, why not just dig out an air spaced solenoid design program to help design the inductor, then design a 3rd order HPF for about 10MHz and wind a large (high Q) air wound inductor in the way a typical radio ham would do. I'd expect a ham to go for fat wire and a L/D ratio close to 1.5.Then sweep the HPF over the range of a typical scanner (2GHz?) and check out just how many suckout dips you see. You are going to see several big ones. Most will be between 10-20dB deep and not the <=2dB you seem to suggest.You can wind different types of (smaller, more loss, powdered iron?) inductor to change the dip responses/frequencies and minimise the depth of any dips but that isn't the point. The point is that the dips are there in the first place and a 2 port model can be used to model the inductor BEFORE it gets fitted to the filter. The model should be able to show you where the dips will appear, how deep they are and how wide they are. All I'm trying to do is offer Simon a practical example where a two port network can be used to good effect."
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 03:32:06 am",
"content": "Note that you can use the same 2 port model for the inductor in a LPF design. eg a 3rd order LPF in the SW band and the model will help predict where the stopband will degrade up in the UHF region. A LPF with a big air solenoid like this could have a stopband that degrades to less than 20dB in places due to (narrow) resonance modes in the solenoid up towards 1GHz. It should be possible to predict this quite well in a simulator once the 2 port model is created"
},
{
"post_id": "",
"author": "Simon",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "February 21, 2017, 07:36:17 am",
"content": "Well I'm lost and a little bit more scared of the topic"
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 05:26:26 pm",
"content": "Quote from: Simon on February 21, 2017, 07:36:17 amThat's possibly because all the complicated stuff Tim posted and linked to after I suggested the inductor studying wasn't really needed. The whole point of an n port model is that you don't 'need' to know anything about the device as long as it is a linear device and you collect VNA data from it in a steady state.Here's a 1 port s parameter model of a shunt inductor at 11MHz. You can see that it is just a single reflection coefficient measurement. Once you start looking at transmission lines you will be looking at reflection coefficients quite a lot.# MHZ S MA R 5011 0.995 97.138A 2 port model of the same inductor will look a bit more complicated because you need to measure and record 4 coefficients with the VNA (not just one) and it will be measured in series between two 50R test ports.# MHZ S MA R 5011 0.399 65.95 0.915 -23.957 0.915 -23.954 0.4 65.927Normally the VNA would produce a 2 port model like this every MHz or so from 1MHz up to maybe 2GHz and store it all in a big data file.But in the case of the high pass filter example you could just use a 1 port (shunt inductor) model made up of hundreds of VNA measurements across 0.3MHz up to 2GHz and use this data file as a model in a HPF circuit in an RF simulator to predict the passband response of the complete HPF. This should be able to predict where the unwanted resonance dips will be in the passband."
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 06:23:07 pm",
"content": "To provide a quick demo, I wound a 500nH inductor using about 9 turns (airspaced) with a 14mm diameter and length 26mm and some 0.7mm wire.I then measured this as a 1 port device using a VNA up to 2GHz. This is just a crude 1 port model of the inductor consisting of 1600 separate measurements of the reflection coefficient of the inductor across 0.3MHz to 2GHz. The VNA doesn't know it is measuring an inductor, it will just provide me with a 1 port model of the inductor.I then entered this 1 port model into a simulator and used it in a simple (50 ohm) 15MHz highpass filter.The network was a series 270pF cap then shunt 500nH inductor (but I used the 1 port model for the 500nH inductor here) then series 270pF cap to make up the HPF.This simulation predicted the high pass filter will have the red trace as below when built and measured. Note all the deep and nasty dips in the passband. Note how they are typically 10-20dB deepThen I actually built a 15MHz highpass filter using this inductor and some decent quality 270pF caps and a decent layout and I measured it on the VNA. The trace showing the real performance of the real HPF is shown in blue. Note how the 'real' dips are also typically 10-20dB deepNote also how well the simulation with the model agrees with the 'real' circuit.You can now see that I was able to model this inductor and predict the misbehaviour that will occur in the passband if the inductor were used in a HPF like this. This shows the benefit of using an n port network derived from a VNA. To try and produce a (very complicated) lumped model or even a complicated tline model to give this level of agreement would be very time consuming and difficult. The VNA can create the 1 port model data in a couple of seconds."
},
{
"post_id": "",
"author": "T3sl4co1l",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 21, 2017, 08:20:37 pm",
"content": "Nice.Yeah, I think that 500nH inductor is below the impedances I was working with, so you should indeed see deeper notches!Tim"
},
{
"post_id": "",
"author": "G0HZU",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "February 22, 2017, 01:43:37 am",
"content": "Yes, this classic big old airwound inductor type gives very deep suckout notches in a filter like this. There are better inductor options but I chose this one as it misbehaves badly hereLeapfrogging over 2 port networks into 4 port, I dug out an old 4 port model and simulation I did of some classic 300 ohm balanced ribbon feeder and posted up a short video on youtube showing a screenshot of the results. I'm lucky to have a decent 4 port VNA here at home and I used it to experiment with balanced transmission line analysis a while back. If each of the 4 wire ends of the ribbon feeder are connected to the 4 ports of the VNA and the reference plane set right at the start of the feeder then it's possible to play with the model on a simulator to see what the insertion loss will be when in a 300R balanced environment. You can see that the loss is lowest at about 307 ohm which is very close to 300R. The loss is also very low.All this investigation work is possible because I took a valid n port model of the ribbon feeder where n is 4 in this case because there are 4 connections in total. The VNA I have here can be configured for balanced ports to let it look at balanced feeders directly but I did this the old school way with a basic 4 port connection and then I put baluns in the simulator to keep the model balanced.Sorry, but there's no sound I don't have a proper mic here and Camstudio is a pain to set up for audio on this Win7 PC anyway. But hopefully you get the idea. It probably won't make much sense to Simon yet but maybe when he has looked at transmission lines and n port networks it will make more sense as this is a classic transmission line that was once popular as a feeder for TV and radio reception in many countries. You can see that I compared the results with a Genesys library model of a 306 ohm transmission line of similar dimensions and it all agrees very closely. Check out that flat group delay!This is a neat way to look for the characteristic impedance of an unknown transmission line over a wide bandwidth. You can see that I did this two ways. I tweaked the source and load impedance for lowest insertion loss at this was about 307 ohm.But I also measured (at low frequencies) the inductance of the line and also its capacitance. As we all know we can calculate Zo from (L/C)^0.5 where C was 7.61pF and L was 724nH. This works out the Zo to be 308 ohm. Pretty close agreement for both methods!In a way I wish I'd done this up to 1GHz or more because the loss is so low. But a big exposed length of cable like this is prone to RFI pickup and you can see a slight blip at 200MHz in the results for group delay. This might have been caused by some external interference.https://youtu.be/xHoQAZBUu2k"
}
] |
2025-10-17T19:02:26.852208
| 29
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-power-supplies-for-a-amp/
|
2 power supplies for a amp - Page 1
|
[
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 25, 2019, 03:57:09 pm",
"content": "Hello,I am looking for a power supply solution to an audio amplifier board which requires +/-24VDC. Most symmetrical power supplies seem to be very expensive, but I thought maybe I can buy two of these cheaper ones?https://www.digikey.com/products/en?keywords=lrs-100-24One interesting note about this amp: although it is a single output amp, it seems to have four output terminals. They are two for ground and the other two are labelled +24V and -24V. I looked at the data sheet, and they are definitely single output, so I wonder also why they have this option.Thanks,"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 25, 2019, 04:49:38 pm",
"content": "That power supply will probably do the job, but you forgot to post the data sheet for the amplifier, so we don't know how much current it requires.Another option is to use two 24V supplies in series and take the 0V from when they join. Connecting a couple of diodes in parallel with each of them is a good idea to prevent either supply from seeing to higher negative voltage, if it current limits or shuts down. The diodes should be rated to a bit more current, than the power supply's rating.Having more than one 0V connection is pretty common."
},
{
"post_id": "",
"author": "soldar",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 25, 2019, 05:00:45 pm",
"content": "It is a single output PSU and you would need two."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 25, 2019, 05:25:34 pm",
"content": "Quote from: Zero999 on September 25, 2019, 04:49:38 pmThanks for your reply.I am sorry I forgot the amplifier! This is what I see, there is a circuit schematic in the pictures.https://www.ebay.com/itm/20W-HIFI-Mono-Channel-LM1875T-Stereo-Audio-Amplifier-Board-Module-DIY-Kits/182588636277?hash=item2a83217c75:g:6OYAAOSw42JZJAU4I plan to use 2 of these together and use some decent heat sinks. So I can use two of the 24VDC meanwell and wire two of these up?Thanks,"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 25, 2019, 05:41:58 pm",
"content": "You have another option, to actually buy a toroidal or regular transformer with two secondary windings or one winding with center tap, then use a bridge rectifier and two capacitors to get your +24v and -24v.Your amplifier probably works with less than 24v and -24v but naturally, will output less audio power."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 25, 2019, 07:43:23 pm",
"content": "Quote from: mariush on September 25, 2019, 05:41:58 pmThanks for the idea, but I'm kind of new to this, so I think that may get too confusing.I think what I want to do is hook up two of these small amp boards:https://www.ebay.com/itm/20W-HIFI-Mono-Channel-LM1875T-Stereo-Audio-Amplifier-Board-Module-DIY-Kits/182588636277?hash=item2a83217c75:g:6OYAAOSw42JZJAU4To two of these power supplies:https://www.meanwell.com/Upload/PDF/LRS-100/LRS-100-SPEC.PDFTo power two small amp boards using 2 PSUs, can I split the +24VDC from one supply to both amp board's +24VDC input, and then take the -24VDC output from the other supply to both -24VDC inputs?Is this safe and correct?"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 25, 2019, 11:38:53 pm",
"content": "Ok, cool.So let me give you some more information.That LM1875 is a class AB audio amplifier chip, which means it's kind of inefficient and therefore will produce A LOT of heat. It MUST be connected to a big heatsink. If you want to get 20 watts per channel, you're going to need a CPU style heatsink with a fan.Here's the datasheet for this chip :http://www.ti.com/lit/ds/snas524a/snas524a.pdfLook at page 4, figure 5:This tells you that with a 8 ohm speaker, the amplifier can function with as little as +/- 10v (the x axis), but the maximum output power will only be around 5w (the y axis). Following the line, you can see it does ~10w at +/-15v, a bit more than 15w at +/- 20v and nearly 25w at +/-25v.With 4 ohm speakers, the output power will be slightly higher.So what you need to get from this is that you don't necessarily need two 24v power supplies, especially if you don't have 15-20w speakers.On the same page, you have figure 8 : Device Dissipation vs Ambient Temperature and this picture must be used together with Figures 9 and 10 on the next pageSo let's say you want to power with +/- 24v ... we'll look on the +/- 25v curves.If you have a 4 ohm speaker, you'll look in the Figure 9 chart - you can see that to produce 15w of audio power, there's gonna be a bit over 30 watts of heat produced.If you go with 8 ohm speaker, you'll look in the Figure 10 chart - you can see that to produce 15w of audio power, there's gonna be nearly 20 watts of heat produced.This heat (20..30w) must be dissipated safely... and that's what Figure 8 shows you.For safety, assume the ambient temperature (the temperature of the box where the amplifier will be) will go up to 40 degree Celsius, so you go on the x axis at 40 degrees C and then you go up.You can see that the bottom two heatsinks (rated for 10c/w or 5c/w) are not good enough.The next curve shows a heatsink rated for 2c/w and it's just barely good enough if you'll do 15w of audio power with 8 ohm speaker (which dissipates nearly 20w)To safely dissipate the 30w of heat you'd produce to get 15w of audio with 4 ohm speaker, you can't even use a 1c/w heatsink on all its own - you'll need to supplement it with a fan to blow air over it and help cool it.As an idea, this is the kind of heatsinks you'd need for 10w+ of heat dissipation :https://www.digikey.com/short/p2mv1qThe link above shows heatsinks with < 3c/w natural convection (<1..2c/w with fans)So my advice would be to first decide on the speakers you're gonna use, and ideally use 8 ohm speakers as these amplifiers will dissipate less heat with such speakers.If you're gonna have a couple of 5w or 10w speakers, there's no point to power this amplifier with +/- 24v, because you can produce 10w with just +/- 15v, and you're gonna produce less heat.Making a power supply using a transformer is very easy, here's a schematic :The unlabeled resistors should be something around 4.7kOhm - 10 kOhm and rated for 1w ... basically, they're there to discharge the big capacitors when the amplifier is not in use.The bridge rectifiers should be something like 6A or higher... they're very cheap...here's a 8A one for 1.25$ :https://www.digikey.com/product-detail/en/micro-commercial-co/GBJ806-BP/GBJ806-BPMS-ND/8554715So let's say you decide you want 15w of audio power and you have 8 ohm speakers. In that case, +/-20v is gonna be enough but we can go with +/- 25v curves.Looking at Figure 10 chart, at 15w of audio, the +/-25v curve tells you there's gonna be nearly 20w of heat produced. So, in total, the audio amplifier needs 15w audio + 20w heat = 35w of power to achieve what you want.For stereo sound, you'll need double this, plus some reserves... so you need something that can give you minimum 70w...Now you can go look for a transformer with either two secondary windings or center tap, which outputs 15v AC or more on each secondary winding, or 30-36v AC if transformer has a single secondary winding with center tapHere's some examples with center tap21$ : 28v AC 100w :https://www.digikey.com/product-detail/en/triad-magnetics/F8-28/237-1722-ND/487865121$ : 36v AC 100w :https://www.digikey.com/product-detail/en/triad-magnetics/F8-36/237-1723-ND/487865232$ (with wires) 35v AC 140w :https://www.digikey.com/product-detail/en/triad-magnetics/F-191U/F-191U-ND/7318079With dual secondary windings :21.4$ 2 x 12v 80w :https://www.digikey.com/product-detail/en/triad-magnetics/VPS24-3300/237-1276-ND/66616221.4$ 2 x 14v 80w :https://www.digikey.com/product-detail/en/triad-magnetics/VPS28-2800/237-1280-ND/66616621.4$ 2 x 18v 80w :https://www.digikey.com/product-detail/en/triad-magnetics/VPS36-2200/237-1285-ND/66617128$ 130w2x12https://www.digikey.com/product-detail/en/triad-magnetics/VPS24-5400/237-1277-ND/6661632x14https://www.digikey.com/product-detail/en/triad-magnetics/VPS28-4600/237-1281-ND/6661672x18https://www.digikey.com/product-detail/en/triad-magnetics/VPS36-3600/237-1286-ND/66617236$ 175w2x12https://www.digikey.com/product-detail/en/triad-magnetics/VPS24-7300/237-1278-ND/6661642x14https://www.digikey.com/product-detail/en/triad-magnetics/VPS28-6250/237-1282-ND/6661682x18https://www.digikey.com/product-detail/en/triad-magnetics/VPS36-4800/237-1287-ND/666173"
},
{
"post_id": "",
"author": "wraper",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "September 25, 2019, 11:45:09 pm",
"content": "Quote from: Zero999 on September 25, 2019, 04:49:38 pmYou need to be cautious with that. Not every PSU will be fine with that, some may have resistor to earth from negative output or even direct connection. Connecting such PSUs in series may cause magic smoke escaping."
},
{
"post_id": "",
"author": "Audioguru again",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "September 26, 2019, 12:54:55 am",
"content": "You selected \"switching\" power supplies that will probably produce low frequency beats and high frequency whining interference. For audio use \"linear\" supplies instead."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 26, 2019, 01:57:52 am",
"content": "Thank you so much for all of the help! Maybe I can do a transformer after all.Quote from: mariush on September 25, 2019, 11:38:53 pmThe speakers I have installed in that room are Bose 141.https://assets.bose.com/content/dam/Bose_DAM/Web/consumer_electronics/global/products/speakers/141_series1/pdf/owg_en_141_series1.pdfThey are widely believed to be 4-6 Ohm, but you know how Bose is about specs! They claim to 'handle' 10-80 watts, but can only deal with 40 watts continuous power. (it says on the back of the case) I picked them up at a yard sale cheap like 20 years ago. I was pairing them to a Aiwa P22 which outputs 30 watts per channel (which I also got at a yard sale) but it broke. I generally never cranked it up past half-way because it was so loud, but it never distorted or clipped at higher volumes.So, as far as power goes, maybe 25 watts per channel isn't crazy?Unfortunately, I'm not sure 100% about the impedance because I was using a Mission M2Sas subwoofer that has a cross-over inside of it. I plug in the speaker output from power amp into the subwoofer and there is speaker output after the cross-over. I don't know how this effects impedance, but I would like to keep using it. If I have to, I could get some kind of pre-power amp cross-over, if the advice is not to use the subwoofer crossover?QuoteOkay. It took me awhile, but I think I follow the graphs mostly. The one thing I don't understand is why the better heatsink is a lower temperature. I would think that 1C/watt would be less heat dissipation than 10C/watt, but the chart shows it the other way around. The temperature value gets smaller until you reach \"infinite heatsink.\" I think I need to better understand the metric to properly order one, right?QuoteOkay, I think I can follow this, but I need time to digest it a little. Also, I think I should figure out what I'm aiming for before I run completely through to spec out the transformer.Thanks again for your help!"
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 26, 2019, 02:57:17 am",
"content": "If you are willing to go with a class D amplifier, you have plenty of choices on eBay.For example, this one is ~25$ :https://www.ebay.com/itm/Mini-Class-D-Power-Amplifier-HiFi-Stereo-2-0-Channel-Digital-Audio-Amp-50W-50W/262315996089It uses a TPA3116D2 :http://www.ti.com/lit/ds/symlink/tpa3118d2.pdfwhich can do :2 × 50 W Into a 4-ΩBTL Load at 21 V2 × 30 W Into a 8-ΩBTL Load at 24 V2 × 15 W Into a 8-ΩBTL Load at 15 VHas the added bonus of a volume knob, and you can power it using a plain wallwart adapter. I think it has a standard 2.5mm barrel jack... either 2.1mm or 2.5mm19$ gets you an 18v 60w adapter:https://www.digikey.com/product-detail/en/mean-well-usa-inc/GST60A18-P1J/1866-2151-ND/770371434$ gets you 24v 90w :https://www.digikey.com/product-detail/en/mean-well-usa-inc/GST90A24-P1M/1866-2157-ND/770372044$ gets you 24v 120w:https://www.digikey.com/product-detail/en/delta-electronics/DPS-120AB-3-B/941-1788-ND/6561830"
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 26, 2019, 04:11:55 am",
"content": "Quote from: mariush on September 26, 2019, 02:57:17 amThanks for your alternative suggestion.I also considered a class D unit. I watched some various tear-downs of the cheap ebay stuff on youtube.About the particular unit you linked to, this one review claims that the choice of output filter coils is optimized for 8 ohm loads and that lower impedance loads experience roll-off in higher frequencies. If you see at 12:33:However, there is this other board here:https://www.ebay.com/itm/392072722443?ul_noapp=trueThat board seems to be a little better and draws about 1.75A at 20VDC:I could probably use a laptop supply with it. I have an orphaned toshiba laptop PSU that does 19VDC 6A. Maybe I should just get two of those mono D boards and split the laptop PSU to both of them?Thanks,"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 26, 2019, 08:06:19 am",
"content": "Quote from: wraper on September 25, 2019, 11:45:09 pmYes, that's very true. The original poster should check the power supplies are floating first, before connecting their outputs in series."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 26, 2019, 06:21:01 pm",
"content": "Quote from: Zero999 on September 26, 2019, 08:06:19 amThanks. I checked the data sheet and it does look like the - side is tied to ground.Can you tell me if i can split a 19v switching laptop supply into two so I can power two mono amp boards like the one I linked above?"
},
{
"post_id": "",
"author": "Zero999",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 26, 2019, 07:32:02 pm",
"content": "Quote from: vol.2 on September 26, 2019, 06:21:01 pmI'm not sure what you're asking.When you mean split, a 19V supply, which would give +/-9.5V, or use two 19V supplies for +/-19V?Splitting a single 19V supply is possible with a virtual earth/ground circuit, but if you want to connect it to external devices, with grounded chassis, you need to check the 19V supply is floating.Connecting two 19V supplies in series for +/-19V is only possible if they're floating. Laptop power supplies vary. Some are floating, others are not. One thing you can do is check what sort of mains connector, the power supply uses. If it's three pole, it will have an earth connection and might not be floating. If it's two pole, then there's now way it's grounded and has to be floating."
},
{
"post_id": "",
"author": "dazz",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 26, 2019, 07:49:11 pm",
"content": "Quote from: vol.2 on September 26, 2019, 06:21:01 pmIf you're referring to the class D TPA3116s that mariush suggested, I think that's the best way to go. They're a lot more efficient and you will save a lot of trouble, money and energy with those by simplifying the power supply. Not sure what you mean by splitting the power supply to feed two boards, what you would do is to use a singly power supply for both boards, but a laptop brick will probably not have enough output current for two TPA3116s with 2 ohm speakers.Do you really need that much power? Because a single stereo TPA3116 board can output 40W+40W with 4 ohm speakers and a single 20V 5A laptop brickKeep in mind that 100W is not twice as loud as 50W."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 26, 2019, 08:14:17 pm",
"content": "Quote from: dazz on September 26, 2019, 07:49:11 pmI'm referring to this mono board:https://www.ebay.com/p/13016014274I would two of them for stereo.QuoteI have Bose 141 speakers, they are ~6ohm.I mean I want to use my 19V power supply to feed both mono boards. I've got a few around, one of them says 4.74A. There was this review that tested the TPA3116 mono board on youtube, and he shows that the boards take about 1.75A each at 20VDC under a 4 ohm load. I am thinking I could get away with splitting the power from the one 4.75A laptop supply to both mono boards. Does this sound right, or am I missing something?Thanks,"
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 26, 2019, 08:16:30 pm",
"content": "I meant to split the one 19VDC laptop supply to power 2 of the mono TPA3116 boards because I need to power 2 of them for stereo. I don't know if that's safe.Thanks,"
},
{
"post_id": "",
"author": "dazz",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 26, 2019, 08:35:43 pm",
"content": "Quote from: vol.2 on September 26, 2019, 08:14:17 pmCouple of things:1. Those are 40W speakers, so having a 100W+100W amp makes no sense, unless you want to blow your speakers.2. If you're gonna be using 6 ohm speakers, you'll never get 100W from one of those boards. The 100W output assumes 2 ohm loads. So you're much better off with a single stereo (BTL, not PBTL) board and a single power supply."
},
{
"post_id": "",
"author": "mariush",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 26, 2019, 08:40:40 pm",
"content": "It would be safe.Note that class D power amplifiers like these TPA ones are more efficient, let's say up to 85-90%... compared to class AB that are ~50% or even less.So if the guy measured the power consumption at 20v 1.75A, that's around 35w in, so assume around 25 watts of actual audio output. Basically, he ran the amplifier at around 2x12-15w.How much power the amplifiers will use will depend entirely on how much you amplify everything, on your volume knob position, how per-amplified your audio signal is and to some degree depends on the audio speakers and their impedance...Yes, there's no reason why you couldn't run two mono amplifiers on a single such power supply. Just keep in mind that at very high volumes the two amplifiers may draw high current for brief moments of time and that could cause the power supply to enter in \"over current protection\" or restart itself ... so you may get \"hiccups\" (power supply turning on and off)edit : I recommend going with my version because you get it in a nice package, with volume control, dc in jacks, input and output connectors and everything.It's also in the standard configuration of 50w + 50w max, so chances are you're not gonna damage your speakers if you accidentally set the volume to maximum ...With two of the other (same chip but configured in BTL mode, mono) you may accidentally damage your speakers and you'll also have to do extra DIY (case, add volume control etc etc)"
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "September 27, 2019, 03:38:55 am",
"content": "Thanks for your input.Quote from: mariush on September 26, 2019, 08:40:40 pmI have a passive volume control with four inputs that goes into the power amp. This will be replacing the power amp in a system I've been using for awhile. Yeah, I guess I'd need a case eventually.Quote from: dazz on September 26, 2019, 08:35:43 pmAccording to the review anyway, this actually maxes out at 50W at 4ohms. Maybe they are only using one channel?If the 141's are 6ohm, then at 19VDC, it should be more like 27W or so? Or is my logic flawed here? Am I crazy?"
},
{
"post_id": "",
"author": "dazz",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "September 27, 2019, 11:09:26 am",
"content": "Those figures are pretty close to the spreadsheet graphs at 4 ohms, probably at 0.1% THD or something like that.At 19V and 4 ohms he's getting about 32W so at 19V and 6 ohms you would get up to 21W if we extrapolate those figures. That's for a single channel.The way that chip works, you can have it configured in BTL stereo mode so that it's a two channel amp that you can drive at 2 x 4 ohms for a maximum output of 50W + 50W, or PBTL mono that combines both channels in a single one that you can drive at 2 ohms, 100W. But again, I don't see the point in getting PBTL mono boards if you're going to be using 6 ohm speakers since the whole point of PBTL is to lower the load impedance to increase the output power. There are also dual PBTL boards like this one:https://www.ebay.com/itm/TPA3116D2-2x120W-Digital-Power-Amplifier-Board-DIY-Kit-Class-D-Dual-Stereo-Audio/202786866259.That's two TPA3116's in a single board for a maximum of 100W + 100W.That might be a good option if you want to take advantage of PBTL in the future with 2 ohm speakers, but be careful not to blow your current ones."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 03, 2019, 01:57:29 am",
"content": "I ended up purchasing the stereo version of the TPA3116 board. I'll use a 19VDC laptop supply and it looks like the max I can push with my 6 ohm speakers will be around 25W a side. I am thinking it will be just about right.I'll post once I get it in the mail and set it up in case anyone who read this thread wants to know what happened."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 10, 2019, 02:44:42 pm",
"content": "I got the little stereo version of the TPA3116 board installed and working in my setup.https://www.ebay.com/itm/TPA3116-TPA3116D2-120W-120W-Dual-Channel-Stereo-Digital-Audio-Amplifier-12V-24V/392072658051?hash=item5b4959fc83:g:5mgAAOSw3ChbMrPQ:sc:USPSFirstClass!20905!US!-1It was pretty easy to get going; I used a 19V 4.8A laptop supply and I jumped the little gain pots on the board because they looked really cheap and I'll never use them. (I also tied the wiper back to the left side of the pot with a resistor the value of the pot in order to keep the impedance identical)It sounds good and clean, but it seems to me that my sound now lacks the energy in the mid range that my setup had with the previous power amp. I'll be repairing the old amp and put it back, but for now this will work.One last question here, in case someone can help me! When I turn the stereo on or off (I use a power strip) there is a pop. Is there some way I can remove this pop by adding some components?This is the board in question:Thanks,"
},
{
"post_id": "",
"author": "fourfathom",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 10, 2019, 03:09:35 pm",
"content": "Quote from: dazz on September 26, 2019, 08:35:43 pmIt's not uncommon to use an amplifier capable of delivering more power than the speakers can handle. When running a lower-power amp near its limits you can get clipping of any transients which can produce tweeter-destroying amounts of high-frequency power. Obviously trying to run 100W into a 10W speaker will also cause problems, but it's not a bad idea to give yourself some head-room when choosing an amplifier."
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 10, 2019, 03:19:45 pm",
"content": "Quote from: fourfathom on October 10, 2019, 03:09:35 pmYes, my previous amp was overpowered and it worked fine at a middle volume. This new amp is also overpowered, but not by as much. Currently, the issue I'm having isn't clipping, it's the pop when I turn off the power."
},
{
"post_id": "",
"author": "dazz",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 10, 2019, 03:20:36 pm",
"content": "Quote from: fourfathom on October 10, 2019, 03:09:35 pmPoint taken. It's just that his speakers are 6 ohms, so a BTL TPA3116 would never get anywhere near clipping territory."
},
{
"post_id": "",
"author": "dazz",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 10, 2019, 03:23:40 pm",
"content": "Quote from: vol.2 on October 10, 2019, 03:19:45 pmhttps://youtu.be/s0vIM8kZx9M?t=420"
},
{
"post_id": "",
"author": "vol.2",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "October 10, 2019, 09:09:48 pm",
"content": "Quote from: dazz on October 10, 2019, 03:23:40 pmThanks, that's an interesting idea. However, it seems a little sketchy because he's pulling the positive current to actuate the Mute function from a pin that TI specifically says not to draw on. He's guessing it's not effecting anything, but I don't have all the diagnostic equipment to tell if it pooches anything.I wonder if there's a more \"standard\" way to implement the mute on startup/shutdown. (his circuit actually doesn't address shutdown)"
}
] |
2025-10-17T18:02:14.094200
| 29
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-questions-about-flux/
|
2 questions about flux - Page 1
|
[
{
"post_id": "",
"author": "apelly",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "October 15, 2013, 09:01:06 pm",
"content": "1) For my whole life, and for the first half of my current spool of solder, flux residue has been brown and fairly minimal. Now it's green, gunky and plentiful. Is this due to soldering at a lower temperature? I'm around 330C at the moment.2) What do you guys use to clean this up? Acetone works, but makes the solder mask sticky. Any suggestions?Aaron."
},
{
"post_id": "",
"author": "Alex",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "October 15, 2013, 09:34:00 pm",
"content": "Regarding #2, you can try isopropyl alcohol (IPA) or a purpose-made flux remover (eg. Electrolube LFFR).Alex."
},
{
"post_id": "",
"author": "deth502",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "October 15, 2013, 10:09:25 pm",
"content": "+1 to alex. ive used the flux remover spray before and it works great. i just dont do large enough jobs for me to justify buy it again. if i do a repair with a few joints, or a small project, i just scrape the heavy flux with a pick and brush the board. but yeah, if youve got a large board to clean, the spray is the only way to go."
},
{
"post_id": "",
"author": "mcinque",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 15, 2013, 10:39:13 pm",
"content": "Quote from: apelly on October 15, 2013, 09:01:06 pmTrichlorethylene. Cheap, well tolerated by solder mask and components, works very very well for me, and it doesn't leaves residues at all."
},
{
"post_id": "",
"author": "nanofrog",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "October 15, 2013, 11:25:25 pm",
"content": "+1 toAlexanddeth502.Quote from: mcinque on October 15, 2013, 10:39:13 pmWorks well, but likely hard to get now (carcinogenic & environmental concerns)."
},
{
"post_id": "",
"author": "apelly",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "October 15, 2013, 11:59:13 pm",
"content": "IPA it is. Thanks guys.I'd still like to know what's up with the green flux though. Soldering leaded onto lead free tinned pads? Seems unlikely. PCBs are coated with nickel aren’t they?"
},
{
"post_id": "",
"author": "kizzap",
"author_rank": "Unknown",
"is_op": false,
"timestamp": "October 16, 2013, 12:13:44 am",
"content": "Are you saying that the flux changed colours half way through the roll of solder? are you perchance working on new boards that you haven't used before?The only other option I can think of is that the solder manufacturer changed their flux recipe half way through a cycle and it just so happened to change in your roll.-kizzap"
},
{
"post_id": "",
"author": "apelly",
"author_rank": "Unknown",
"is_op": true,
"timestamp": "October 16, 2013, 12:48:11 am",
"content": "Quote from: kizzap on October 16, 2013, 12:13:44 amYes and yes. Haven't tried going back to something I've worked on before. Will do.Quote from: kizzap on October 16, 2013, 12:13:44 amSeems pretty unlikely.Aaron."
}
] |
2025-10-17T20:15:01.158625
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-questions-equivalent-transistors-and-creating-a-0v-rail/
|
2 questions - equivalent transistors and “creating” a 0v rail - Page 1
|
[
{
"post_id": "",
"author": "Dan123456",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 30, 2023, 04:37:26 am",
"content": "Hey allFirstly, apologies if the 2 questions in one post format is frowned upon here! I figured it was better then spamming new threads and as the old saying goes “it’s better to ask for forgiveness rather than for permission”My first question is, is there a real quick and dirty way of working out if a transistor will work in a circuit for hobby situations?I was searching online and found some fairly useful pages that list about 10 things you should compare and use a transistor with the same or “slightly higher” values. That makes perfect sense for professional work / stuff you want to actually put to work but can that be dumbed down even further for just hobby messing around (I.e. what are the most critical values and what is “slightly higher” - I.e. like max 20%)?Specifically, I am looking to just build a little crapy FM receiver to feed into some audio amps and all the diagrams I have found seem to have obsolete / hard to find transistors listed. On the latest schematic asks for a few BF324’s. Using alltransistors.com to run an equivalency search brings up a whole bunch but the closest ones all seem to be obsolete / hard to come by too!My second question is regarding creating (or more specifically grounding) a 0v rail. I had the idea of creating a variable positive and negative power supply using my 12VAC wall power supply (thank you so much again to everyone who recommended that to me previously! It has been a blast to play with!), a bridge rectifier, a LM317T and a LM337T.However, after looking for schematics, I saw they were all connecting the 0v rail to the AC earth. As far as I understand, my AC power brick only has 2 prongs so doesn’t have an earth.My question is, do I have to connect that 0v rail to earth by running a cable to the earth of a PowerPoint (or more realistically, via the earth pin on my proper lab bench power supply) or is there another way I can do it?Please feel free to tell me I’m an idiot on this oneI tried researching it but came across a whole bunched of new terms from google such as “earth ground” vs “signal ground” vs “digital ground” vs “analog ground” and left more confused than when I started :pIt very well could be the case that I am just not ready for this project yetThanks so much in advance once again all"
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2023, 10:50:56 am",
"content": "Hi,This is probably easy to figure out but you should post a schematic to make sure everyone understands exactly what is needed. There are sometimes subtle differences that need to be addressed and without a schematic these differences may not be understood properly. A simple schematic clears it all up."
},
{
"post_id": "",
"author": "Dan123456",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 30, 2023, 11:46:16 am",
"content": "Quote from: MrAl on September 30, 2023, 10:50:56 amSorry! That’s a fair point!For the FM radio / receiver, I have 2 versions on hand. The one I was talking about uses the BF324’s and the other uses BF494/495 transistors. Pretty much I am wondering if pretty much any old transistor would “work” in their place (even just poorly - provided you aren’t using a NPN in place of a PNP or something wildly different like that)? Or if you really, really do need to match all the transistors values as closely as humanly possible otherwise the circuit isn’t likely to work at all (and if this is the case, how far “off” can you usually go before you are likely to run into major issues?)?As for the adjustable positive and negative power supply, I was thinking something close to the 3rd picture but using adjustable voltage regs rather than 12V ones. Issue is, it looks like the 0V goes back to the din socket to go to earth via the wall where as I will be using a 2.1mm Jack from my 12VAC wall wort power supply that doesn’t have a ground pin that plugs into the wall (only active and neutral on the plug that goes into the wall).Hope that helps and thanks so much once again"
},
{
"post_id": "",
"author": "Manul",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2023, 01:01:29 pm",
"content": "I suppose first pass of choosing transistors is looking at maximum voltage, current, power. Very dumb, very obvious. Next pass is looking at more specific parameters like Beta, transition frequency, maybe capacitances, noise figure. Generally you want transition frequency to be well above working frequency, otherwise you will not get good performance if any. Beta might be important, but depends on the circuit. Most circuits if well designed should be fairly tolerant to (sensible) transistor substitutions, so don't be afraid to experiment.Regarding the 3rd picture, the 0V is the middle tap of AC transformer secondary, not mains earth. Of course, you may choose to connect that secondary middle tap to mains earth if you wish, but it's not a functional necessity. In one case you get mains earth referenced supply, in another - isolated floating supply. But in any case middle tap is essential for this kind of balanced rectifier which rectifies into positive and negative rails."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2023, 01:35:10 pm",
"content": "For the BF324, look atBF824- Its SMD (SOT23), but other than that is near-identical. How did I find it? Well, put key parameters into a distributer's parametric search (e.g. Mouser), starting with fTand Vce, selecting a range from the desired value to about double it. Also select 'In Stock' and see what pops out. Add parameters one at a time in order of decreasing importance, to reduce the no. of results. When the list gets down to a reasonable number of items (<50), sort by price ascending then start looking for the best match, checking datasheets as distributor parametric search databases aren't entirely trustworthy.As Manul just said, the 0V on the DIN socket probably didn't go back to mains PE 'earth' ground. I'd also bet it was fed by a center tapped transformer and the center tap is '0V'. Each half of the secondary gives 11.5V RMS. The total voltage across the ends would be 23V RMS.I gather you have a 'wallwart' transformer with a single 12V RMS output, so you cant use the balanced bridge rectifier circuit. Instead you need matching positive and negative half-wave rectifiers. In the above circuit delete D3,D4, increase the 1000uF capacitors to 2200uF, and connect your transformer in place of pins 2,3 of the DIN socket. You have to double the capacitors because they are fed with pulses of current at half the frequency the full-wave circuit feeds them at, so need more capacitance for the same amplitude ripple."
},
{
"post_id": "",
"author": "Dan123456",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "September 30, 2023, 02:34:09 pm",
"content": "Awesome thanks allIan.M, Thanks for the half bridge idea mate! I am still new to the world of AC and got confused when I remember there is no nice easy positive and negative to work withYeah I tried that in Digikey (I haven’t given Mouser a crack yet! Will have to keep them in mind!) but was filtering out SMD packagesMy hands shake like I’ve been on a week long bender at the best of times so am still just buying little SMD practice boards at this point to try and get my skill up with that stuff before I try and make anything using those bloody tiny little thingsIs there an issue with going significantly above the rating? I.e. I sometime see some that look good but are 50V+ higher on the Vcb value or what have you.Sounds like lower values are a no go (which is pretty much what I expected) but is there an issue with going too much higher?Like let’s just say for arguments sake I was to find a transistor and all the values were double that of the original. Would that be a good option or is it better to find something closer to the original (and if so why? I’m guessing twice as “good” usually means twice the price but would that be the only downside?)?Thanks so much again everyone"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2023, 02:52:45 pm",
"content": "Lower values may or may not be a no-go. See the specific circuit for what the transistor is actually being run at (do the math!), then allow generous margins on voltage, current and power. E.g. your BF324 circuit uses a 5V supply, so 15V Vceo transistors would probably work. However, the closer the ratings are to the one you are trying to match, the more similar its likely to be, so the odds of matching other parameters NOT available in the parametric search improve, resulting in less digging through datasheets before you 'get lucky'. Pricing is all over the place, and often depends on popularity rather than performance! e.g. a high sales volume 'jellybean' part may be both cheaper and higher spec. than a niche market legacy part."
},
{
"post_id": "",
"author": "MrAl",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "September 30, 2023, 05:32:54 pm",
"content": "Quote from: Dan123456 on September 30, 2023, 11:46:16 amHello again,Very good, and as you see you get some good answers now.To add a little...Yes, that 0v point is the center tap of a center tapped secondary of the transformer. That allows you to use full wave rectification for both positive and negative supplies.The half wave suggestion is good, but you will need to double all your capacitor values to get the same degree of ripple filtering. Not too big of a deal though i think.There are other tricks for getting a zero voltage output for plus and minus supplies, but they are a little more involved. That would allow you to get plus and minus with full wave rectification, but not sure the extra circuitry would be worth it. For low current though it can be very easy.If you can get hold of a center tapped transformer you can use the original power supply drawing, something to think about."
}
] |
2025-10-17T16:47:36.958566
| 8
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-questions-no-relation/
|
2 questions, no relation - Page 1
|
[
{
"post_id": "",
"author": "DoublesAdvocate",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 03, 2023, 01:07:52 pm",
"content": "I have a few broken PS3's (CECH-4XXX) that refuse to read discs. After a bit of google and some prodding with a multimeter I've determined that one of the little SMD fuses near the drive circuitry has blown. I'd love to replace it and get the consoles reading again but I have no idea what the value(s) of the fuse is as there aren't any markings on the fuse or board and (obviously) there are no repair manuals or documentation for the device online. Does anyone know of a way that I can determine the value of the fuse? I do have a donor board where I can test a working version of the fuse, but it also has no markings so I'm at a loss for HOW to actually test it, suggestions?Question #2 is:I'm trying to build a passive headphone/mic mixer and would like some sort of switch that can swap the function of 2 pins on a TRRS connector so it can support both common microphone wiring configurations. Does anyone have any suggestions for what type of switch I can use for this?"
},
{
"post_id": "",
"author": "wasedadoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 03, 2023, 03:05:09 pm",
"content": "Quote from: DoublesAdvocate on May 03, 2023, 01:07:52 pmIf the fuse is the only problem on the broken board you can measure the current that normally flows through it by bridging it with a multimeter set to measure current. Start with the 10A range or whatever is in that ballpark. If the PS3 then reads discs note the highest current and get a fuse say 50% higher than that."
},
{
"post_id": "",
"author": "themadhippy",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 03, 2023, 03:38:15 pm",
"content": "QuoteA red one?seriously, more info needed of what your trying to achieve would be useful,"
},
{
"post_id": "",
"author": "wasedadoc",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 03, 2023, 04:17:07 pm",
"content": "Quote from: DoublesAdvocate on May 03, 2023, 01:07:52 pmDPDT"
},
{
"post_id": "",
"author": "DoublesAdvocate",
"author_rank": "Newbie",
"is_op": true,
"timestamp": "May 03, 2023, 10:09:48 pm",
"content": "Quote from: themadhippy on May 03, 2023, 03:38:15 pmSorry yeah I think what wasedadoc suggested is what I'm looking for.Basically there are 2 common wiring configurations for headphones, CTIA and OMTP. The wiring they use for the output of sound/music is the same between them but the configuration for inline microphones swap poles and I'm trying to build a circuit that you can select manually rather than having to rely on detection circuits.(not sure if I embedded that correctly)Quote from: wasedadoc on May 03, 2023, 03:05:09 pmOkay perfect, I'll give that a shot."
}
] |
2025-10-17T16:55:10.962129
| 5
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-rectifier-diodes-in-parallel-to-dim-a-120v-15a-heater/
|
2 rectifier diodes in parallel to dim a 120v 15A heater? - Page 1
|
[
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 07:26:03 pm",
"content": "I have a bunch of 10A10 rectifier diodes (datasheet:http://www.rectron.com/data_sheets/10a05-10a10.pdf). They're rated for 10A current.Since the IR heater element is rated at 15A, that's obviously more current than the diodes can handle. But could I wire 2 of the diodes in parallel, so that only 7.5A is passing through each one?I've read that some people say it's fine most of the time, and that it's rare for problems to arise from using diodes in parallel. But others seem to say that since the diodes are never the same rating, that one will get hotter than the other, causing it to absorb more current, and then get hotter, etc.What do you guys think? Is it too risky to use the diodes in parallel like that? Or is it wrong for my particular application? Am I overlooking anything with this idea?I'm not sure if I'm ever actually going to do this. I'm just interested in learning about the possibilities.Thanks!"
},
{
"post_id": "",
"author": "BobsURuncle",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 07:48:47 pm",
"content": "Show how they would be used in the circuit"
},
{
"post_id": "",
"author": "madires",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 07:50:05 pm",
"content": "The problem with paralleling diodes is the thermal runaway of Vf. With increasing temperature Vf decreases, i.e. the diode will pass more current. So the current won't be distributed equally across the paralleled diodes. If you use diodes of the same batch (assuming their Vf is about the same) add some additional diodes for a better current distribution allowing some variation without exceeding the limit. Maybe use 3 or 4 diodes in your case."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 08:06:39 pm",
"content": "Quote from: BobsURuncle on May 16, 2016, 07:48:47 pmThis is probably the first one I've ever made, so go easy on me!"
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 08:07:17 pm",
"content": "Quote from: madires on May 16, 2016, 07:50:05 pmThanks for the info! It's nice to know that using 3 or 4 together makes it much safer."
},
{
"post_id": "",
"author": "edpalmer42",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 08:21:50 pm",
"content": "As you stated, it's fine most of the time. Is it good practice? Certainly not!The worst case of diodes in parallel that I've seen is in a 13.8V 50A power supply that I picked up some years ago. It's a commercial product rather than a DIY special. I didn't believe it when I opened it up and found a full wave rectifier arrangement where each of the two rectifiers is made from twenty-five 3 amp diodes in parallel! Yes, a total of 50 1n5402 diodes!It seems to work but........ Do I like it? Would I ever do something like that? No flipping way!!Ed"
},
{
"post_id": "",
"author": "BobsURuncle",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 08:21:57 pm",
"content": "Or mount them on the same heat sink and put a 0.01 ohm 1% 2W resistor in series with each. Mounting on the same heat sink will help to limit the temperature differential and the resistors would provide some negative feedback to prevent runaway."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 08:29:33 pm",
"content": "Quote from: BobsURuncle on May 16, 2016, 08:21:57 pmAre resistors with values <1 ohm common? The smallest resistor I have is 1 ohm at 3W. Would I be able to do anything with that? Is it useful to have resistors with such small values on hand?I have some old pcbs from some broken stuff, like old coffee makers, etc. Is there a chance there might be some <1 ohm resistors there?"
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 08:30:06 pm",
"content": "If you want to play real safe place ballast resistor in series with each diode.Note you have to get one rated for the power. You can sim this in spice easilyand see what the variation in currents would be for a different Vf.Regards, Dana."
},
{
"post_id": "",
"author": "langwadt",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 08:39:14 pm",
"content": "Quote from: Jay112 on May 16, 2016, 08:29:33 pmjust use separate with wire to and from each diode and make them as long as practicala meter of 0.5mm^2 copper wire is roughly 0.033 Ohm and has positive temperature coefficient"
},
{
"post_id": "",
"author": "BobsURuncle",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 08:50:24 pm",
"content": "Quote from: Jay112 on May 16, 2016, 08:29:33 pmYes readily available..I don't know what your board layout plan is but here is a 29 cent SMD at NewarkMCS3264R010FERor a more expensive axial leaded12FR010EIt needs to be low resistance for low power dissipation and because the current through a diode is exponentially related to the voltage across it. A quick back of the envelope calculation and I got 0.01 or so ohms. Maybe someone could run a simulation to get a more reliable number or since this is just a one-off you could experiment a bit with the diodes you have."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 09:15:26 pm",
"content": "Here is a diode ballast sim as a trial, attached. Monte Carloon one R, 20% variation.Regards, Dana."
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 09:19:46 pm",
"content": "5% R tolerance Monte Carlo. attached.Regards, Dana."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 10:59:57 pm",
"content": "Thanks everyone for the help and the tips!!I think I'm just going to stick with using 4 of the diodes in parallel, without any resistors or anything else. Recently I decided to build this circuit now, because it'll probably only take 5 minutes, and I'm curious to see how it works. I'm working on fixing the regular PCBs for these heaters (I have 3 broken heaters now, each worth $350!), but that's going to take me a long time.Do any of you think that there's any chance of harming a heating element by giving it a rectified AC signal? Technically wouldn't that cause the element to only be receiving half the power, so that there's a greater chance of extending the element's life rather than shortening it?"
},
{
"post_id": "",
"author": "BobsURuncle",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 16, 2016, 11:00:30 pm",
"content": "The variation to worry about is the Vd vs If of the diode, presumably the Is and n tolerances. A .01 or .02 ohm ballast resistor will only work if he can find two closely matched diodes. 0.1 ohms would almost certainly work but would dissipate as much power as the diodes. The diode data sheet doesn't offer any guidance, but assuming he bought these all together off one reel they would be a lot closer than what a datasheet tolerance would indicate anyway."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 11:02:16 pm",
"content": "Quote from: BobsURuncle on May 16, 2016, 11:00:30 pmThanks for the info. I bought a pack of 50 of these all at the same time. Also I could test the 4 I'm using, to make sure they're similar, right?"
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 11:12:45 pm",
"content": "It took me a while, and I had to go through the entire bag, but I finally found 4 diodes that tested exactly the same with my multimeter! I was surprised how different they all were! It seemed the values ranged from 5.2 to 5.6. I got 4 that were all 5.37. (I didn't have time to look it up, but I assume it was measuring the voltage drop? I just put the meter on the diode test mode)."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 11:19:24 pm",
"content": "I hooked the diodes up to a 60w bulb, and it successfully dimmed the light. What could possibly go wrong when I hook it up to a big heater, right?If this is my last post ever, y'all know what happened."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 11:28:43 pm",
"content": "Yay, it works! Thanks everyone!!!"
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 16, 2016, 11:54:06 pm",
"content": "Do you guys happen to know any neat/simple ways that I could use to dim the half-wave rectified power even further? Is there an easy way to cut the rectified power down by another half?If I'm starting with 120Vrms AC, with a peak voltage of 170, then after the diodes I should be getting 60Hz pulses of 170v DC, correct? Is there an easy way to halve those pulses?The reason I'm asking is because if I can find a way to do that, then I could implement a switch that allows me to choose between full power, half power, and quarter power. Then I wouldn't even have to rebuild the original circuit boards, as described in this tedious thread here:https://www.eevblog.com/forum/beginners/possible-to-reverse-engineer-this-pcb-heater-controller/"
},
{
"post_id": "",
"author": "Photon939",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 12:21:38 am",
"content": "Quote from: Jay112 on May 16, 2016, 11:54:06 pmThe way I have seen this done in large electric duct heaters is a solid state relay with a little PIC mcu doing some low speed PWM. Frequency around 0.25Hz or so. Heater on, heater off. Prevents crappy power factor and buzz caused by dicing up each sine wave. Then you can have nice analog control of the heat output while also allowing you to do whatever control scheme you please with the mcu.Going a bit simpler than that you could buy a china 555 timer relay board and set a low duty cycle on that and use it as a lower power option with an extra switch or something."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 17, 2016, 01:03:01 am",
"content": "Quote from: Photon939 on May 17, 2016, 12:21:38 amThanks for sharing! Those are neat ideas!I've never heard of flipping an SSR on and off frequently, but it sounds nice and easy. Technically I could just use an Arduino Nano, hook the SSR up to a PWM output, and use an analog pot to adjust the frequency of the PWM, right? I wonder how good that would work across the full power range. Do you see any problems with this method? Am I overlooking anything?"
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 17, 2016, 01:04:07 am",
"content": "Question I had right after I posted: Don't SSRs only work with AC? So that would only work if I removed the rectifier diodes first, right?"
},
{
"post_id": "",
"author": "radar_macgyver",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 02:36:46 am",
"content": "Yep, lose the diodes.Also, try to locate an SSR that has an in-built zero-crossing detector. The SSR will go from off to on only when the AC cycle crosses zero. This will significantly reduce the stray emissions.The period of the PWM would depend on the thermal mass of your heater. I found that electric baseboard heaters work well with a period of ~5 seconds. Any longer than that and you can hear them \"crackle\" when they heat up/cool down."
},
{
"post_id": "",
"author": "edpalmer42",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 02:56:35 am",
"content": "Really all you're describing is a big light dimmer. Then you could set it to any level. No SSR, no Arduino or PIC. Bad news is I don't know if they make dimmers that big.Ed"
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 17, 2016, 03:06:31 am",
"content": "Quote from: radar_macgyver on May 17, 2016, 02:36:46 amThat's all really interesting! I had no idea the crackling noise could be avoided! I noticed that only 1 of my heaters didn't make noises, but I didn't know how.Could you please explain to me a little more about the emittance? I was reading a datasheet on a zero voltage switch today, and it was describing how the RFI was eliminated due to the zero crossing switch, but I didn't know what that means. What's the problem with emittance? How would it affect the circuit or other things/people nearby?Edit: Also, how does switching at zero volts stop the emittance, and how would starting at a different point cause more?"
},
{
"post_id": "",
"author": "Photon939",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 03:15:42 am",
"content": "The zero crossing switching means there is no current flowing when it changes state. When triacs suddenly switch on during the sinewave like a typical lamp dimmer it can cause radio interference from the sudden current spike and if bad enough can actually interrupt or crash electronic devices nearby (much more of a problem for inductive loads though).Turning off my soldering station used to sometimes crash my 3d printer. I had to install a MOV across the transformer primary."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 17, 2016, 03:22:59 am",
"content": "Quote from: Photon939 on May 17, 2016, 03:15:42 amThat's really interesting! Thanks for the info!Is it not a problem when power is cut in the middle of the wave? It only happens when power is starting, not when it's stopping?"
},
{
"post_id": "",
"author": "radar_macgyver",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 04:06:55 am",
"content": "Triacs will, once triggered, continue to conduct as long as there is current flowing between the two main terminals. When the AC cycle reaches zero, current should drop to zero and turn off the triac. This automatically takes care of the turn-off happening only at the zero crossing. The detector circuit is still needed for turn-on, though."
},
{
"post_id": "",
"author": "IconicPCB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 08:26:58 am",
"content": "Diode only method will play havoc with your local power distribution transformer...not to mention the LED lights and ceiling fans perhaps in the hood."
},
{
"post_id": "",
"author": "RGB255_0_0",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 08:37:19 am",
"content": "And your Wi-Fi"
},
{
"post_id": "",
"author": "danadak",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 10:14:43 am",
"content": "You can get power triacs up to ~ 100 A, just use one a control circuit.See attached selector guide done for 30A.Regards, Dana."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 17, 2016, 11:18:08 am",
"content": "Quote from: danadak on May 17, 2016, 10:14:43 amThanks Dana! I actually already have some CQ3P-25M triacs that can take 30A, and that's what the original pcb for the heater was using with a zero voltage switch. The problem was that the triac burned out, but it wasn't an easy replacement because some of the traces on the board got burned too, and the entire thing was covered with potting so it was difficult for me to rebuild the circuit without understanding it fully. I'm about 90% through being able to rebuild the circuit from scratch, but it's not easy for me and I had to do a lot of studying to get there, and I feel like I need another month to fully understand how the circuit works. That's why I was looking for a temporary alternative solution."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 17, 2016, 11:26:06 am",
"content": "Could you guys please explain why it would wreak havoc on the power distribution lines, and on other things like wifi? My guess was that maybe it weakens the top half of the AC sine wave, causing an imbalance, which causes other devices on the same line to get imbalanced power? And maybe the imbalance also creates a large electromagnetic field around the device, messing with some wireless stuff and inductive loads?The heater originally comes with 2 different kinds of controllers (the first 2 in the list below), and I was wondering if you guys could please share your opinions about which of the following methods you think is safest in terms of interference with other devices:1) Zero-voltage switch triggers a triac. The timing is dependent on an analog pot and a thermistor.2) A thyristor adjusts the firing angle of the wave, control is by a single analog pot. The heaters with this method seem loud, making buzzing noises when not on full power. Also I've had interference problems with this method, with nearby lights flickering or dimming depending on the heater's setting.3) Half-wave rectifier diodes to dim the power to about half.Also, is there another common dimming method for high-power resistive loads, or is it that the first 2 are by far the most popular?------Edit: Also I guess another method was already mentioned above by radar_mcgyver: To use a pwm signal to control an SSR that has an in-built zero crossing detector. But technically that would affect the power in exactly the same way as method #1 above, right?"
},
{
"post_id": "",
"author": "IconicPCB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 17, 2016, 10:51:52 pm",
"content": "A triac with adjustable conduction angle is likely to introduce harmonic distortion and potentially power factor issues into the distribution network.A better option is to use zero crossing detection and drive the heater in block control mode.. block as in a block of integer periods of power supply .This will produce switching disturbances on the line but the resultant distortion will be negligible compared to phase control method.Both above methods will have a symetrical loading on the grid during positive and negative periods of AC voltage.( Ok may be half a wave might slip through here and there ).A diode method will ALWAYS present asymetric load to the grid. The resulting current will be asymmetric.This asymmetric current will flow through the distribution transformers ( ugly things sitting on powerpoles ).Asymetric current == DC current. Transformers are intended to operate in alternating current environment.A DC current will cause the magnetic flux in the transformer to be higher in one half of the waveform. This means the transformer inductance will be different between the two halves of the wave. If inductance is different the resulting current will be asymetricbetween the two half waveforms.. creating harmonics.. in fact as DC current goes up.. the magnetic core becomes biased allowing higher magnetising current peaks to flow through the transformer ( leakage reactance ). this means transformer gets hottr.. surrounding equipment gets exposed to gigher levels of harmonics.Led lighting starts to flicker.. ceiling fans start to hum audibly..stuff gets stressed out... Your power meter does not show correct power usage... Power distribution authority starts to hunt for source of distrbance.. You get stuck with a bill .Well not necesarily .. depends on the transformer and the burden it was designed to supply and burden it is actually handling."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 17, 2016, 11:52:32 pm",
"content": "Quote from: IconicPCB on May 17, 2016, 10:51:52 pm@IconicPCB: Thank you so much for the detailed information!! It's interesting to me that the effect can even be seen by the power company. Do you think a single 120V heater is able to cause that much trouble, or would it usually require more power? After I installed the diodes, I measured the amperage at 6A. I incorrectly stated earlier that the unmodified heater draws 15A, but after double-checking I learned that it says 12.5A.I have a few simple questions (for anyone), if you don't mind:1) Hypothetically, if I put 2 of those heaters side by side, and had 1 using only the positive half of the wave, and the other using only the negative half of the wave, would that balance everything out?2) Is there an easy way to use only the negative half of the wave? Like maybe some kind of special rectifier diodes that only allow negative current to pass through?3) Are there any regional regulations that cause manufacturers to have to be careful with the amount of power distortion their devices are producing?"
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 18, 2016, 12:44:16 am",
"content": "Sorry if I've overlooked the heater description some where.Question: Are the heaters just a resistive coil with a separate controller? Or, is the temperature controller built into the unit?If the former, wire two units in parallel for full power and wire two units in series for half power. It would only need a simple switch with no worries with interference with WIFI, cordless phones, etc. I would need to do a little doodling to see if a DPDT switch would do the trick.Edit. You would need the verify that the controller could handle two units in parallel !!!"
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 18, 2016, 01:24:17 pm",
"content": "Quote from: MarkF on May 18, 2016, 12:44:16 amThat's a really neat idea about wiring them in series! I never thought of that! I'll have to keep that in mind.If I did wire 2 of them in series with no controller board, and with 120v mains (USA), then technically would each be pulling half of its usual (12.5A) power, thereby making the total power consumption the same as if I was using just 1 heater on full power?The heating element looks like a 4-foot long resistor, similar to how an oven bake element looks but straightened. BTW, since it's classified as an \"infrared\" heater, does anyone know if this makes it have different emissions than something like an oven bake element?As for the controllers, they all basically broke in different ways, so that's why I'm either trying to rebuild the original controllers, or make my own. On one the triac burned out, and on another the zero voltage switch got fried. But replacing the triac or the switch didn't fix these, so there seems to be other problems too. And a 3rd heater that broke recently has a different type of controller, and on that one the thyristor definitely blew out (it was like an explosion!), but replacing the thyristor didn't end up fixing it, so I have to search for other problems on that board too."
},
{
"post_id": "",
"author": "MarkF",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 19, 2016, 03:08:25 am",
"content": "Quote from: Jay112 on May 18, 2016, 01:24:17 pmYes. You would be doubling the resistance with two resistive strips in series, thereby halving the current by applying the same voltage.Keep in mind that the current will be DOUBLE when you put them is parallel."
},
{
"post_id": "",
"author": "Circlotron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 20, 2016, 03:11:43 am",
"content": "Quote from: Jay112 on May 18, 2016, 01:24:17 pmNot quite. Double resistance of two in series = half current. Also each heater now has half voltage. Half voltage x half current means each heater is 1/4 normal output. Total of two heaters = half normal output of one heater at 120V."
},
{
"post_id": "",
"author": "Raj",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 20, 2016, 06:00:06 am",
"content": "try bta20Triacs could be really rugged, My dad built one in 1980s, its still workinghttp://uk.farnell.com/stmicroelectronics/bta20-600cwrg/triac-20a-600v-to-220ab/dp/1057283https://www.google.co.in/search?q=20a+triac&oq=20a+triac&aqs=chrome..69i57j0l5.3907j0j7&sourceid=chrome&ie=UTF-8https://www.google.co.in/search?q=triac+based+regulator&newwindow=1&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjIkbqi_efMAhWHe6YKHbmoBm8Q_AUIBygB&biw=1366&bih=643#imgrc=cS-F8Ax-JizfjM%3A"
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 21, 2016, 01:30:43 am",
"content": "Quote from: Circlotron on May 20, 2016, 03:11:43 amThanks for the info! Now it's seeming pretty messy to me to hook up 2 in series. I just wanted to brainstorm the idea a bit.Those zero crossing SSRs seem on the pricey side! Lots were in the $40-$60 range, but I found one with correct specs for $28 with free shipping. It's an Omron that can handle 20A at up to 240V, and it takes 5VDC for the input, so I think I could easily hook it up to an Arduino's PWM. I might buy it at least for experimentation."
},
{
"post_id": "",
"author": "IconicPCB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 21, 2016, 05:34:45 am",
"content": "Dont use it in the PWM mode.Devise a block firing controller.say...if heater on and sensor reading below setpoint fireelse switch offkind of an approach.You might even want to try to model delay between heater going off and sensor registering it to provide some rate control."
},
{
"post_id": "",
"author": "ali6x944",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 21, 2016, 07:31:46 am",
"content": "See this:Quote from: IconicPCB on May 21, 2016, 05:34:45 amQuote from: IconicPCB"
},
{
"post_id": "",
"author": "Kleinstein",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 21, 2016, 09:05:45 am",
"content": "Parallel diodes should be thermally coupled to reduce the tendency for thermal runaway. Also a little resistance, like separate longer wired help.Using just the diode for larger loads is not nice to the grid. Depending on the country it is tolerated for portable / handheld tools - many hair-dryers use this method to get the lower power setting. Having two such circuit in parallel with opposite direction will cancel out the DC current (at least most of it) - so this would be no problem. With the diode the power per heater will be about half. With two heaters in series the power per heater will be 1/4 the nomonal power.Also remember that IR emissions are a nonlinear function of the temperature and power. So if you give only half the elctrical power to the IR element, the output IR power can be way lower than half.If it is just to get a longer lifetime, one might consider a transformer to reduce the power a little, like 20 %. So a 110/12 V transformer might be enough. The transformer only needs to be rated for the current so something like a 140 VA would be enough for the 12 A current.In the US the transmission transformers are often relatively small, so that a smaller DC current might upset them - especially the small pole mounted ones might have a problem with this. With a larger transformer like in city areas or in much of Europe (due to higher voltage and thus longer permissible lines) the transfromers can stand more DC current."
},
{
"post_id": "",
"author": "IconicPCB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 21, 2016, 12:22:01 pm",
"content": "Ali6x944,There is a difference between PWM drive and phase locked PW drive required to effect zero ross over variable conduction angle drive.Just stating PWM is insufficient and may result in undefined drive conditions."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 21, 2016, 01:01:40 pm",
"content": "Quote from: Kleinstein on May 21, 2016, 09:05:45 amWow, Kleinstein, I think you just answered every question in the thread! Thanks!!This forum has so many knowledgeable users! It's unbelievable!There's a green metal transformer box just outside my house. I'm not sure why they put it there, but I'm in a rural area, the previous owners were farmers, and I have a long driveway (maybe 500') so it's far from the road.Does having the transformer on the ground just outside the house provide any different effects than if the transformer was on a pole? Or has everything you guys said about mains transformers taking the hit still apply?"
},
{
"post_id": "",
"author": "Circlotron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 21, 2016, 02:21:20 pm",
"content": "You probably have a high voltage line on the road and along the driveway leading up to this transformer, which drops the voltage down to 120VAC for your house. Drawing half wave dc from the mains will affect only this transformer and consequently only your house. If you are running the transformer at a reasonable percentage of it's rating and then also make dc flow though it you may trip a circuit breaker or fuse somewhere on the high voltage side and you will be in the dark until the electricity company arrives to fix it."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 21, 2016, 02:34:07 pm",
"content": "Quote from: Circlotron on May 21, 2016, 02:21:20 pmThanks for the info, Circlotron! I'm glad to know that I'm not affecting any of the neighbors!I've been running these kinds of IR heaters for years (some of them are for my livestock), sometimes all at the same time, without noticing any problems. So for example in the winter I might have 3 IR heaters running at the same time, 2 with a zero crossing switch and the 3rd with a phase controller, along with other high power stuff, and so far I haven't noticed any big problems."
},
{
"post_id": "",
"author": "IconicPCB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 22, 2016, 06:22:25 am",
"content": "Winters must be cold.. helping keep your transformer cool.How many wires do you have coming off the transformer?"
},
{
"post_id": "",
"author": "Raj",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 22, 2016, 02:46:45 pm",
"content": "i just remember reading an article about using non contact ir paired up with triac and microcontroler (microcontroller isolated via opto coupler triac) as thermostatcould easy write a program if you want one."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2016, 10:34:56 pm",
"content": "I got a 20A zero-crossing SSR, and I tested it for my first time today. Everything works correctly when I have a 60W light bulb hooked up to it: I can turn the bulb on or off, and have it flash at different frequencies with PWM.But when I hook up the IR heater to it the heater never turns on.When I remove the rectifier diodes (the ones we installed earlier in this thread) that were being used to dim the heater down to about 50%, then the heater works as expected with the SSR: I can have it turn on and off, and anywhere in-between. When I put the diodes back in, the heater doesn't work with the SSR. If I have the diodes in and I skip the SSR and plug the heater directly into the mains, then it works as expected with the diodes dimming it about 50%Does anyone know why the heater won't work with the SSR when the rectifier diodes are being used?This is the schematic I tried to draw. There wasn't an SSR symbol available and since I didn't know what to use I just used a symbol for a switch."
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 11:05:12 pm",
"content": "If by \"SCR\" you mean a thyristor (as opposed to a triac), the clue is in the name; Silicon ControlledRectifier."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2016, 11:14:24 pm",
"content": "Quote from: Andy Watson on June 01, 2016, 11:05:12 pmThanks for responding, but there are no SCRs in my circuit. Just a zero-crossing SSR, a half wave rectifier diode, and the resistive load of the heater."
},
{
"post_id": "",
"author": "Circlotron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 11:28:31 pm",
"content": "SSR = solid state relay.Probably the SSR needs to see both half cycles for it's zero crossing detect circuitry and other internal low power stuff to operate. The diode is cutting off one half cycle so it is going strange internally. Does anything change if you reverse the diode?Edit -> did you mean it worked okay with the diode in circuit on the globe but not the heater?"
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 11:44:56 pm",
"content": "Quote from: Jay112 on June 01, 2016, 11:14:24 pmOops, sorry, my mistake (the afluence of inccohol is strong tonight!). But, a \"zero-crossing\" SSR will require a zero-crossing - which the series diode prevents."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 01, 2016, 11:55:38 pm",
"content": "Thanks guys!I just tried reversing the diode, and it still didn't work.Also I hadn't tried the diode + lamp before, and I just tried that now. It had the same result as the heater: the lamp doesn't turn on at all when the diode is in the circuit, no matter which direction the diode is pointing.It sounds like you guys got it right that the SSR needs to see the voltage crossing past zero. I wonder if there's any way to make a tiny \"bounce\" past zero, even with the rectifier diode in place. Any ideas?"
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 01, 2016, 11:59:57 pm",
"content": "Quote from: Jay112 on June 01, 2016, 11:55:38 pmYou might be able to fool the SSR by arranging for some negligible leakage across the diode - perhaps a low wattage lamp? It doesn't need to be much - just enough to the trip the zero-crossing detection in the SSR."
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "June 02, 2016, 12:21:02 am",
"content": "You need enough of an unrectified load on the SSR for it to see a full AC waveform. It would *probably* work if you added an 18K 1W resistor from the SSR switched Live output to Neutral, unless the SSR requires a minimum load current >6.6mA.However for the reasons other posters have listed above, diodes to reduce the power of a high current load are a dumb idea that can get you in trouble with your electricity supply company, so I wouldn't recommend leaving the diodes for half power in there.If you are implementing cycle skipping control, you need a line frequency reference to your control circuit so you can avoid skipping half cycles, and only skip whole cycles, also to avoid DC imbalance. One approach is to use the line frequency input to clock the PWM through a D type flipflop before feeding it to the control terminals of your zero crossing switching SSR.You can derive a suitable line frequency signal by tapping one of the AC outputs from the transformer to the bridge rectifier of a conventional linear PSU, and feeding it through a resistor with a Zener clamp (to 0V) to reduce it to your desired logic level. That gives you a somewhat assymetric line frequency near squarewave, with fairly poor rise and fall times. Clean it up with a Schmitt trigger input buffer before you do anything else with it."
},
{
"post_id": "",
"author": "Jay112",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "June 02, 2016, 06:25:19 am",
"content": "Thanks for the help and ideas, everyone!Just to see if it would work, I just tested your ideas of using a small lamp/resistor across the SSR. I found a 3-watt 74 Ohm resistor, and it worked! I calculated that it was probably drawing about 1.2mA of [email protected], I appreciate your advice about safety, and my ultimate goal is to be able to recreate the original circuits that came with these heaters but which have broken. Ultimately I'm hoping to put together a board that uses a zero-crossing switch (with adjustable pot) to fire a triac that powers the heater."
}
] |
2025-10-17T19:17:46.123378
| 60
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-rpi-zero-w-to-1-spi-2-8-monitor/
|
2 RPi Zero W to 1 SPI 2.8" monitor - Page 1
|
[
{
"post_id": "",
"author": "antolanca",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 08, 2018, 08:52:13 pm",
"content": "Hello everyone. I'm wanting to build a visor using 4 Raspberry Pi Zero W, 4 cameras (2 IR, 2 Thermal) and 2 monitors smaller than 3\" each. However, all monitors I can find below that size are all connected in SPI instead of HDMI. Now the Pi has only one camera input hence why using one per camera (I can use usb but then would lose FPS which is important on a visor. At least it's what I've read online) and I am happy to use the SPI connections.However, so far no one has been able to explain to me as to how can you connect a switch in order to switch from displaying Pi 1 to displaying Pi 2.And even Youtube videos explaining how SPI works don't actually give me any ideas as to how can I switch from one to the other.If anyone could explain to me how it actually works and how can I switch from one to the other (in very lay man terms please) I would very much appreciate it.Thanks in advance."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 08, 2018, 09:04:13 pm",
"content": "Forget about SPI display it is slow. Search resulted in <3\" RPi display, so they exist. You just have to search them:https://thepihut.com/collections/raspberry-pi-screens/products/adafruit-pitft-2-8-touchscreen-for-the-raspberry-pi"
},
{
"post_id": "",
"author": "antolanca",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "December 08, 2018, 09:53:29 pm",
"content": "That display uses SPI.\"The plate uses the high speed SPI interface on the Pi and can use the mini display as a console, X window port, displaying images or video etc. Best of all it plugs right in on top!The plate uses the high speed SPI interface on the Pi and can use the mini display as a console, X window port, displaying images or video etc. Best of all it plugs right in on top!\"But what I actually need is a switch."
},
{
"post_id": "",
"author": "tsman",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 08, 2018, 10:03:51 pm",
"content": "You say \"2 IR, 2 Thermal\" but there isn't a thermal camera module that is compatible with the CSI interface on a RPi so you're down to only two cameras across two RPi Zero boards. If you're using the NoIR RPi camera then be aware that the colours for some things are all messed up since it is lacking the IR cut filter."
},
{
"post_id": "",
"author": "ogden",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "December 08, 2018, 11:07:51 pm",
"content": "Quote from: antolanca on December 08, 2018, 09:53:29 pmOuch, how did I miss that. Sorry. I thought that all their displays haveDPI interface"
},
{
"post_id": "",
"author": "Kasper",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "December 09, 2018, 06:23:08 am",
"content": "Quote from: tsman on December 08, 2018, 10:03:51 pmIts easy to add a switchable IR cut filter.Google 'ir cut filter switch'And should probably get an illumination sensor too so you know when to switch the switch.And maybe some IR LEDs too but be careful with those, they can be high enough power to damage eyes while not being visible."
}
] |
2025-10-17T18:20:27.020605
| 6
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-sided-pcb-how-to-make-use-vias-for-gnd-plain/
|
2 sided PCB - How to make / use vias for GND Plain - Page 1
|
[
{
"post_id": "",
"author": "made2hack",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "May 29, 2014, 02:41:03 pm",
"content": "Hi All,So, I am wondering how everyone goes about connecting SIDE A to SIDE B of a 2 sided PCB? How do you make connections from your top to your bottom components? Or, if you are using side 2 for GDN plain, how do you make the connection?I've found theseCopper Rivetsbut at 21 Euros / 100, they seem rather expensive. I mean, 21 euro cents per connection?Am I missing something? Can't I for example simply melt some solder in the hole connecting A to B? Or maybe just a metal pin? Like a jumper pin? Or a piece of copper wire?Also, what about using \"Side B\" as a large GND plain to dissipate heat?I want for example, SIDE A to have LEDs soldered on it, and the GND trace from SIDE A to connect to SIDE B so that the entire SIDE B can be used as a heat sink and where I could then attach another heat sink to it (seeing as the PCB board is nice and flat). How would I achieve this? Should I just solder some thin strips of copper or aluminium between SIDE A & B?Thanks,"
},
{
"post_id": "",
"author": "Araho",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 03:16:54 pm",
"content": "I'm assuming you are talking about boards you make yourself now, because every board I've had made professionally plates the vias without any fuzz.What I do on my home-etched (/school-etched) boards is simply strip a small piece of wire, and solder it in there. This provides good contact, and is fairly quick to do."
},
{
"post_id": "",
"author": "made2hack",
"author_rank": "Frequent Contributor",
"is_op": true,
"timestamp": "May 29, 2014, 03:27:49 pm",
"content": "Yeah, this is for DIY PCB, like the plain copper pcb you subsequently etch."
},
{
"post_id": "",
"author": "Neverther",
"author_rank": "Regular Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 03:31:24 pm",
"content": "Remembered this:http://hackaday.com/2012/10/03/through-hole-electroplating-in-your-home-lab/"
},
{
"post_id": "",
"author": "SeanB",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 03:42:15 pm",
"content": "DIY board simply place a copper wire into the hole and bend over top and bottom and solder. For heatsinking then you just use a thick thermal pad to handle the uneven surface and place a heatsink on the back, with enough screws such that the board does not warp, or with a front brace to apply even pressure.If the entire back is a ground plane with no traces you can even use some thermal epoxy and stick the board down to the heatsink with it, after filing or sanding the back to remove the bigger solder bumps, but not cut the wires off, just expose the copper slightly.Edit WRT electroplating method. If the board is simple and you need only a few through holes and a few traces there isa a way where you make the board and etch it first then through plat the holes. The trick is to make all traces a single unit during layout, with a set of stub traces that run together into star points that are later, after you plate the board, simply drilled out to separate the traces. Done on larger SRBP boards with conductive ink traces so that they can electroplate the silver interface material onto the copper to improve reliability. You see this in a pattern of holes with 3 or more short thin traces running to them across the board. Works on low frequency boards only of course."
},
{
"post_id": "",
"author": "Dago",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 03:51:05 pm",
"content": "Just put a strand from a multistrand wire to a hole and solder it.But IMO no sense in making PCBs yourself anymore (unless you're in a super hurry). 50x50mm two layer PCBs cost literally ten dollars from China."
},
{
"post_id": "",
"author": "free_electron",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 04:58:58 pm",
"content": "Quote from: trs80 on May 29, 2014, 02:41:03 pmyou can't really make plane's on a double sided board... the plane effect requires tight coupling. unless you are doing flex boards or boards thinner than 16 mils it is not going to be a plane...second , to work really right a ground plane's need a power plane as well. this mandates that you use 4 layer boards.Quotesimply use the snipped off legs of passives like resistors. to go top to bottom. Do your layout such a way that you use component pins as via. then you simply solder them top and bottom. works great on IC's and resistors and ceramic caps. elco's are difficult as you can't reach under the body (radial elco's)Quotethat requires thermall mass or thermal conducts. only possible if you can fill the hole with solder. requires electroplating the hole walls. not doable at home.Quote"
},
{
"post_id": "",
"author": "Jeroen3",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 05:37:55 pm",
"content": "Put the board in vertical position using a vice.Grab the bin of normal 1/4w resistors you've used on breadboard, but were unwilling to put back in the sorted cabinets.Solder these in your via's, then cut the lead with a proper sidecutter.While designing the board, keep in mind that your via capabilities are limited. Try not to put via's under other component bodies."
},
{
"post_id": "",
"author": "M4trix",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 29, 2014, 05:55:50 pm",
"content": "Speaking of which, someone tried Bungard's Favorit press? The question is, does it make sense to have this tool for small turnarounds since it's quite expensive. The press is $300 bucks, tools are $127 and pack of 1000 rivets, $30 bucks.http://www.tme.eu/en/details/bun-favorit/soldering-devices-others/bungard/http://www.tme.eu/en/details/bun-favtools-08/soldering-devices-others/bungard/#http://www.tme.eu/en/details/bun-rivetes-08/soldering-devices-others/bungard/#http://www.bungard.de/index.php?option=com_content&view=article&id=48&Itemid=65&lang=english"
}
] |
2025-10-17T20:01:27.691451
| 9
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-spdt-switch-to-control-a-lamp-in-2-different-locations/
|
2 SPDT switch to control a lamp in 2 different locations - Page 1
|
[
{
"post_id": "",
"author": "joersam24",
"author_rank": "Contributor",
"is_op": true,
"timestamp": "June 12, 2012, 03:23:27 pm",
"content": "hi to all,Can anyone show the wiring diagram of 2 SPDT switch that can switch on and off a lamp independently in two separate locations? Thanks..."
},
{
"post_id": "",
"author": "deephaven",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "June 12, 2012, 03:49:07 pm",
"content": "Do you mean two switches? If so, this:"
}
] |
2025-10-17T20:33:21.306663
| 2
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-speed-fireplace-fan-switch/
|
2 Speed Fireplace Fan Switch - Page 1
|
[
{
"post_id": "",
"author": "Larsson55",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 26, 2024, 10:22:20 am",
"content": "I had a fireplace insert for 22 years and was working very good but 2 months ago it developed cracks on the welds and had to replaced with a similar unit. The old and new units have the same fan arrangement and if I knew that I will have a problem with the new one I would have kept the old fan arrangement.The problem with the new fan unit is it has low and high speed settings (like the old unit) but the low speed is pathetic slow and the high speed is very high. Is there anything I can do to get the low speed a bit higher?The attached wiring schematic is wrong, the fan switch has 3 positions High OFF Low.Thanks"
},
{
"post_id": "",
"author": "Ian.M",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 26, 2024, 11:06:20 am",
"content": "Probably not. All the speed control is happening inside the fan motor as the external speed switch only selects which terminal to power. Back in the day it was common to use series capacitors (of the motor 'run' capacitor type) to drop the speed of small fractional HP induction motors when very little startup torque was required (primarily fans and non positive displacement pumps). However nowadays its more likely to have electronic speed control with the speed set by some custom programmed, often unidentifiable IC, with no obvious way to tweak the speed(s).If the motor does have a capacitor between the black and red wires (almost invariably mounted externally on the motor frame, maybe in a plastic housing) you can investigate and try a higher value one, which also needs to be of the 'motor run' type (a regular film capacitor or non-polarised electrolytic typically wont stand up to the high RMS current in this application) and of the same or higher voltage rating."
},
{
"post_id": "",
"author": "CaptDon",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "November 26, 2024, 01:33:10 pm",
"content": "One possible solution is to leave the unit set on high speed and rig up a ceiling fan motor speed controller to your fan. Simple lamp dimmers are usually a bad choice to control motor speed. The ceiling fan speed controllers are different from lamp dimmers and are designed for induction motors. If it is a two wire unit (simply goes in series with the motor, as most are) you could even rig a bypass switch to jump out the speed controller to create the high speed. You did allude to the fact that you thought high speed was too high so perhaps the speed controller will be the best solution, the low you want and the high which isn't hurricane speed. Generally the fan motor speed controllers are significantly higher priced than a lamp dimmer. I seem to recall $30 to $40 U.S.D. You would laugh at my woodstove rig. A modified Leeds and Northrup P.I.D. unit driving a bi-directional motor that drives a fan motor speed controller via a velcro slip clutch. The clutch is a disk of fuzzy velcro driving a disk of fuzzy velcro allowing the drive to slip at the ends of travel. There is a thermistor positioned to sense available heat and if there isn't any heat a comparator circuit turns the fan off. Basically, light the fire and let the controller do the rest. Fan speed is set by sensed outlet air temperature, higher temperature = faster fan speed."
},
{
"post_id": "",
"author": "Larsson55",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "November 26, 2024, 02:22:06 pm",
"content": "Somehow I knew it would be impossible / difficult to fix since the assembly only includes the fans, wiring and the switches but I had to ask.My thanks to both,"
}
] |
2025-10-17T16:27:12.152338
| 4
|
electronics
|
beginners
| true
|
https://www.eevblog.com/forum/beginners/2-stage-op-amp-single-suppy-and-an-arduino-what-is-wrong-with-my-circuit/
|
2 stage op amp, single suppy and an arduino, what is wrong with my circuit? - Page 1
|
[
{
"post_id": "",
"author": "xchip",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2014, 08:57:18 pm",
"content": "Hi guysI hope you can help me, as a learning exercise I built the circuit in the pic. I'd like to know what is wrong with this particular circuit The input to the amplifier is just a coil.I am sure I am making a pretty basic mistake but I dont see it! :-)Details- I am using the 5v and the GND from the Arduino- The op amp is an LM324- R is 10KI am looking forward to your opinions :-)Cheers!xchip"
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2014, 09:17:37 pm",
"content": "The positive input to the second op-amp has no provision for bias current - it is effectively floating. Then you appear to have shorted-out the signal at the input to the ADC."
},
{
"post_id": "",
"author": "DrGeoff",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 06, 2014, 09:22:53 pm",
"content": "In addition, why do you need the capacitors on the op amp outputs when you have biased everything at half rail? It looks like you are also wanting to bias the ADC input to half rail, however as Andy points out, you have shorted it to half rail, killing the signal. Just remove the capacitors between the op amps and remove the connection between the ADC input and your bias supply."
},
{
"post_id": "",
"author": "xchip",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2014, 09:36:25 pm",
"content": "Hi! Thanks for your prompt reply! Inline:Quote from: Andy Watson on May 06, 2014, 09:17:37 pmHow would you fix this? Should I put a resistor from the + input to ground?Quote from: Andy Watson on May 06, 2014, 09:17:37 pmAfter the cap I am just getting positive and negative values around zero, the ADC wont handle negative values that is why I need to add 2.5volts to center the signal.Thanks!xchip"
},
{
"post_id": "",
"author": "xchip",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2014, 09:39:20 pm",
"content": "Quote from: DrGeoff on May 06, 2014, 09:22:53 pmAfter each op-amp I get a small DC offset. The second op-amp amplifies the DC offset of the first one and the signal gets clipped. I put a cap after each op-amp to remove that dc offset.Is there any pdf or tutorial that explains how to do this the proper way?? I havent seen any!Thanks!"
},
{
"post_id": "",
"author": "DrGeoff",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 06, 2014, 09:43:53 pm",
"content": "Quote from: xchip on May 06, 2014, 09:39:20 pmThat's normal. You can calibrate it out by trimming the input offset bias at the first stage.Since you have not given details of your input signal/sensor, then it can't be assumed that it can be AC coupled."
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 06, 2014, 09:45:34 pm",
"content": "Quote from: xchip on May 06, 2014, 09:36:25 pmResistor to the 2.5V reference.QuoteConsider the answer to previous question!Although, I have to say I agree with the Dr., remove the caps. With a total gain of only ~100 you won't be (much) troubled by offset voltages."
},
{
"post_id": "",
"author": "xchip",
"author_rank": "Regular Contributor",
"is_op": true,
"timestamp": "May 06, 2014, 11:24:11 pm",
"content": "Quote from: Andy Watson on May 06, 2014, 09:45:34 pmHi Andy and the Dr,I removed the caps and it is working nicely, thanks!Now I would like to understand how to make it work with the caps (in case I want to use a higher gain)And what is the principle/reason that requires those resistors to be there? I've been googling for a while but couldnt find anything! Feel free to point me to a resource/link that I could read :-)CheersRaul"
},
{
"post_id": "",
"author": "Andy Watson",
"author_rank": "Super Contributor",
"is_op": false,
"timestamp": "May 07, 2014, 12:20:42 am",
"content": "Quote from: xchip on May 06, 2014, 11:24:11 pmIn a nutshell: nothing's perfect! You need to consider what happens if, bysome means, those capacitors become charged. The resistors are there to \"leak\" away that unwanted charge - in this case to your 2.5V reference level. The LM324 is a bi-polar op-amp, its input transistors require a \"bias\" current - 20nA according to the data sheet. This is a very small current but you can't ignore it - it needs to be considered when you design the circuit.Dave did a video a while back - it was primarily about offset errors, but it also explained why and where they arose. At the risk of being flamed to a crisp I'm going to suggest \"The Art of Electronics\" as a readable introduction to the basics (yes I know it lacks the rigorous mathematics that the pedants require).If you feel you must reduce the offsets consider where/which stages of the amplifier are going to contribute the most error and decouple them. Another trick that you might consider is that it is very easy to subtract offsets in software."
},
{
"post_id": "",
"author": "DrGeoff",
"author_rank": "Frequent Contributor",
"is_op": false,
"timestamp": "May 07, 2014, 12:35:47 am",
"content": "Quote from: Andy Watson on May 07, 2014, 12:20:42 amIf the sensor is a DC voltage or current output then decoupling the gain stages will not work. Instead you need to add trimming to the input to trim out the offset that will appear at the output. This is part of the analogue input calibration procedure. Offset nulling and full-scale calibration."
}
] |
2025-10-17T20:02:40.762214
| 10
|
electronics
|
beginners
| true
|
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