Hacking A Dynamic Electronic Load Circuit To Use Function Generator? Solved - Page 1
Forum section: electronics / projects

author: t1d
author_rank: Super Contributor
timestamp: August 28, 2018, 07:03:31 am
content: EDIT: This thread results in two Auxiliary Function Generator input circuits... One, as an additional option, for Jay's Dynamic Electronic Load Design. And, two, another that does not use Jay's Function Generator option. Many, many thanks, to those that participated, in the work. And, of course to Jay, for the original E-Load circuit, itself. The hack would not have come together, without them!I am working toward building Jay Diddy B’s Dual Supply Dynamic Electronic Load. You can find it, here:https://www.eevblog.com/forum/projects/dynamic-electronic-load-project/.The schematic, for my adaptation, is attached, below.Note About My SchematicJay has told me that the values of my resistors for the Meter Output are incorrect… As is, they, in total, produce 25mV. I am working on getting them changed. (If you know the formula, feel free to calculate the value.)And, I mislabeled the op amps... I used the quad symbol, of the LT1014, but labeled it as the dual LT1013. Creating a final schematic, for Jay's project, and for my personal preferences, is in the proofing stage. This is how this was just discovered.Disclaimer: I have posted these questions, within Jay’s thread. They have not been answered. I think, because they add project creep. To avoid that, I think it better, to post them as a separate thread, because this is for my own singular purpose.A prominent feature, of the design, is an on-board square wave oscillator that can be used to test the slew rate of power supplies. I want this feature, but I have several Function Generators, that have auxiliary outputs. I’m thinking that I would have many more options (a sign wave, in particular, variable frequency, etc.,) if I removed the on-board oscillator and added an input, for a Function Generator. I am an intermediate noob and these design questions are beyond my knowledge base. So, I would appreciate your help.Adapted from previous post:If using an independent function generator would add functionality greater than the on-board oscillator, where, and how, should it be injected, in the circuit? Just use the type jack that breaks the circuit? Break Before Make? What issues might there be?If using an independent function generator is not wise, then I would keep the existing oscillator. If I wanted to add a switch, to bring in, or cut out, the oscillation section, without spinning its adjustment knob, to zero, where, and how, would it go?Would there be any great advantage to using ten-turn pots? I would think that, for home-lab use, things just aren’t going to need to be so precise. Thoughts?It is most likely that I would be using the function generator that is in my Tenma Universal Test Center 72-1005. The auxiliary output is selectable; 50 Ohm, or 600 Ohm.Its operation manual and schematic are too big to post. I have placed them in a DropBox, so that you can know exactly what we are working with.https://www.dropbox.com/hIf you have trouble getting them from DropBox, just send me a PM with your email address and I will send the files to you, direct.I am concerned that some of its functions might damage the Electronic Load circuit… Like the pulse feature… Or, too much input gain. The operation manual explains all of its features.Thank you, in advance, for your help. In appreciation of your support, I would be glad to post the completed KiCad schematic file, for my version. (I am already set up to release Jay Diddy B's design, on his thread.)

author: t1d
author_rank: Super Contributor
timestamp: August 31, 2018, 04:05:33 pm
content: I discovered the answer to my question, in Jay_Diddy_B's original thread:"If I replace the square wave oscillator say with wave gen that capable of producing various pulse shapes like sawtooth, triangle, shark fin, sine and etc, again, as above, will it affect the loop stability ?""The U3 -input (on the LTspice model) is a summing node. You can add the output from your signal generator, through a 100K resistor, to this input. You can then use all the waveforms in signal generator."

author: David Hess
author_rank: Super Contributor
timestamp: September 01, 2018, 06:38:53 pm
content: Quote from: t1d on August 28, 2018, 07:03:31 amThey are the same operational amplifier though so it does not matter. I actually prefer using duals for easier layouts. The LT1006 is the single version of the LT1013/LT1014. Note that these are improved direct replacements for the 358/324.QuoteThat makes sense but the design at your link is not intended for fast dynamic operation. Power supply slew rate is tested with a much faster open loop circuit.QuoteI would probably inject it as another signal into inverting summing amplifier U3. This would allow combining it with the existing DC load control signal although most function generators can generate a DC offset.QuoteThere is nothing wrong with the function generator idea. Some 2 quadrant power supplies support this and I assume some 2 quadrant dynamic loads do as well.While not ideal, it is probably best to open R18 to disable the square wave function.Quote

author: t1d
author_rank: Super Contributor
timestamp: September 02, 2018, 03:07:36 am
content: Good stuff, David. Thank you, so much.Quote from: David Hess on September 01, 2018, 06:38:53 pmFaster speed and different wave shapes shapes is why I wanted to explore this.Quote from: t1d on August 28, 2018, 07:03:31 amFor a clamp, just a typical zener diode application?

author: David Hess
author_rank: Super Contributor
timestamp: September 02, 2018, 06:01:23 am
content: Quote from: t1d on September 02, 2018, 03:07:36 amThere are lots of ways to clamp a signal and a zener diode (or two) is certainly a candidate. It does not have to be complicated or precise.

author: t1d
author_rank: Super Contributor
timestamp: September 02, 2018, 06:43:24 am
content: Thank you!

author: t1d
author_rank: Super Contributor
timestamp: September 02, 2018, 11:01:36 am
content: David,RE: Zener ClampDavid,I have been reading about zener clamps. Best I can tell...- I would inject the Function Generator signal, before Pot #2. This would allow the FG signal to be attenuated, by the pot.- I would base the calculations of the clamp on the fixed resistor value of 100 ohms, as this is the minimum resistance of the pot and resistor, together. But, wouldn’t this resulting variable resistance mess up the resistor to cap relationship?- I need to calculate the cap value to accommodate the upper speed of any frequency that I would inject. My FG only goes to 20MHz, but I want to make the E-Load as versatile as possible. What would be a good number, for this frequency, to do general testing?- The FG signal swings positive and negative. But, doesn’t the E-load circuit need the signal to just be positive? Meaning that I need a Positive, Unbiased Clamper?- The voltage reference supplies 2.5v. So, doesn’t the clamper need to limit the signal voltage to 2.5v?Thanks for your help, with these noob questions…

author: MarkF
author_rank: Super Contributor
timestamp: September 02, 2018, 11:10:02 am
content: I did something similar. If you feed the set voltage into the "+" input instead, you don't need a negative supply. You still would need to clamp the input to 0-5V.

author: David Hess
author_rank: Super Contributor
timestamp: September 02, 2018, 02:42:04 pm
content: Quote from: t1d on September 02, 2018, 11:01:36 amA series coupling capacitor? It would only change a little as shown.QuoteThis design is never going to reproduce a 20 MHz signal. Just achieving 1 MHz would be a challenge which is why I said power supply testing usually uses an open loop pulsed load.QuoteThat is right. Since this electronic load only supports 1 quadrant operation, the signal from the function generator should be clamped to prevent negative operation.QuoteThat is how it would normally be done but it also depends on other details like gain of the separate circuit paths.

author: t1d
author_rank: Super Contributor
timestamp: September 02, 2018, 03:49:58 pm
content: Thank you, David. Good information. I will have to process it, a bit...

author: t1d
author_rank: Super Contributor
timestamp: September 04, 2018, 10:04:34 am
content: David,Here is the Zener, I am thinking of using.Nexperia NZX2V4A,133Zener Single 2.4V 4% 500mW 2-PinHere is the clamp design that I propose. A 100K resistor, already exists, at the injection point.Is a capacitor needed? Most clamp designs seem to have it. If so, how do I calculate its value?I would think that using a resistor divider network, to drop the input voltage, before the diode, might be a good thing. But, I don’t know what to expect, as the common auxiliary output voltage, of frequency generators. Do you have an estimate?My Tenma FG’s output reads asOutput Amplitude2Vpp to 20Vpp at open load1Vpp to 10Vpp at 50 ohm loadWould it be good to use a 51 ohm resistor, to terminate the e-load FG input? I may have not worded that correctly.Thank you, for all your help.

author: David Hess
author_rank: Super Contributor
timestamp: September 04, 2018, 11:53:16 am
content: The frequency response is so low that a terminating resistor will not be needed for the function generator.Why is the zener diode in series with the function generator input? Clamping requires it to be in parallel with a series resistor to limit the current.

author: t1d
author_rank: Super Contributor
timestamp: September 04, 2018, 03:09:49 pm
content: Quote from: David Hess on September 04, 2018, 11:53:16 amBecause I didn't have it straight, in my mind... lolZener Capacitor CalculationsThe capacitor must have enough charge, to last the entire period of discharge.Here, we will assign the slowest frequency (thereby having the longest discharge period) that the function generator might provide, as 1 Hertz. The capacitor charge time is one-half of the complete wave cycle. Therefore, for this calculation, T = 1 and 2T = ½. A safety factor of 10 x T will be included. The resistor will be 100 ohm.Resulting Formula5RC=T/25(100)C = 1/2500C = ½C = 0.5/500C = 0.001uFC = 1nF, aka code 102Do I have the math correctly? Thank you, so much.The corrected schematic is attached.

author: David Hess
author_rank: Super Contributor
timestamp: September 04, 2018, 05:05:18 pm
content: That is not going to work. The inverting input of the operational amplifier is a virtual ground point (summing junction) so the voltage never changes there. Directly connecting the coupling capacitor to that point will destabilized the operational amplifier.Given your current design, I would expect a 100k resistor between the junction of the zener diode and coupling capacitor and the summing junction or maybe a 50k resistor on each side of the zener diode junction if you want to keep the coupling capacitor.Note that such high impedances like 100k are going to limit frequency response because of stray capacitive coupling.

author: t1d
author_rank: Super Contributor
timestamp: September 04, 2018, 05:34:45 pm
content: Thanks, David, I will keep at it.

author: t1d
author_rank: Super Contributor
timestamp: September 05, 2018, 02:56:00 pm
content: Quote from: David Hess on September 04, 2018, 05:05:18 pmQuote from: t1d on August 31, 2018, 04:05:33 pmDavid, I am a bit confused. I understand that you are suggesting changes, to the clamping circuit. But, are you also saying that I am not injecting the FG signal, into the circuit, at the correct place. If so, I think that I am at the location that Jay suggested. So, where is the best spot? After sorting this out, I will have questions, about the added components. Thank you!EDIT: If the capacitor is not needed for biasing, then, without good benefit, I do not want to add it. Maybe a drawing would help and I could reverse engineer the understanding of the operations... Thanks, yet again...

author: David Hess
author_rank: Super Contributor
timestamp: September 05, 2018, 05:56:26 pm
content: The summing node works fine for injecting the signal and the function generator schematics that I checked do it that way but you cannot clamp the input there because as a virtual ground, it essentially never changes voltage.Technically you could clamp the signal in series by liming the current into the summing node from the auxiliary input but that gets away from simple zener clamping. I would consider this I wanted a very fast and very accurate clamping level.

author: t1d
author_rank: Super Contributor
timestamp: September 11, 2018, 04:28:49 am
content: Quote from: David Hess on September 05, 2018, 05:56:26 pmDavid, I moved the injection point to in front of the R21 100K resistor. I tied the sink, for the clamping diode and resistor, to -9v. Is that what you are explaining, in the quote?Quote from: David Hess on September 05, 2018, 05:56:26 pmI don't mind a more complicated design. Is there a name, for this technique/circuit? Or, could you point me at a link, so I can learn about it and get a design? Just a good old transistor current limiting circuit? Or, does it need to be faster?

author: JS
author_rank: Frequent Contributor
timestamp: September 11, 2018, 07:14:18 am
content: I don't know the problem with the thing going low, certainly a zener from the negative rail won't help much. In the case the input goes negative the load will turn it self off and nothing really bad will happen. In the case you don't want it as it will disturb the dynamics of it you could clamp it from a different place. A good option could be adding a diode in parallel with each feedback cap of the driver amplifiers so the output can't go too negative and keeps the cap from charging too much and one in parallel with R16 so the output can't go too positive and they all recover faster. With this you could use a negative input to turn the load off but the recovery from that state will be much faster than letting all saturate and wait smacked up to the rail.With that I'd take out the coupling cap, just run from DC so you can control the load with an external reference and forget completely from the external reference, with this and a programable AWG you can set up any test for a wide range of conditions to run and go to take a coffee as the measurements are ready for evaluation.Also, I'd sum the signal to the proper point, so a resistor to the inverting input of the amplifier replicating R21 for the external input.Having some series resistor with the input and some attenuation doesn't seem like a bad idea to me either, any signal generator will go well over what you need for this load reference...So, my circuit would be a 50Ω load to ground, a 100k resistor to pin 13 of U1D and the diodes in the feedback of each opamp to provide fast recovery. If you want you could add an input attenuator (change the 100k resistor might not be practical as two decades up it's just too big to work properly).JS

author: t1d
author_rank: Super Contributor
timestamp: September 12, 2018, 12:25:31 am
content: Good stuff, JS. I will be trying to draw your design, in schematic form. If you could provide a drawing, for me to work from, it would help, as I still have noob limitations... I really appreciate your participation.

author: t1d
author_rank: Super Contributor
timestamp: September 12, 2018, 01:08:39 am
content: Quote from: JS on September 11, 2018, 07:14:18 amWell, I have to admit, just with a first look, I am confused. U1D is an individual MOSFET load, isn't it? How would it distribute the signal, to all the MOSFETs. I apologize, if this is a basic question. I am still learning how the circuit works.And, it might be easier to communicate, using the schematic that I am adapting. I have attached it, here, in its entirety. I should have provided, the complete schematic, and not just the summing node, earlier. My apologies.

author: JS
author_rank: Frequent Contributor
timestamp: September 12, 2018, 05:40:28 am
content: I can't se te schematic, tapatalk Xiang Sant me to download pdfs... Will check it later on the pc.Sorry if i messed the naming, I'm pretty sure I was talking about the general opaml, not a single driver to get the signal into.JS

author: t1d
author_rank: Super Contributor
timestamp: September 13, 2018, 01:19:14 am
content: This is the only information that I found that is on-point, after hours of additional (frustrating) research. It is only general, in nature. It shows the Function Generator signal injected into the op amp, with no conditioning, between the positive [this being a non-inverting example] input and ground... Even though it is an ac circuit.http://gpete.blogs.keysight.com/2012/03/building-electronic-load-with-general.html

author: t1d
author_rank: Super Contributor
timestamp: September 13, 2018, 01:48:57 am
content: Quote from: JS on September 12, 2018, 05:40:28 amOops. my mistake... Yes, the first post of the schematic lists the op amp as U1D... But, this schematic was, later in the thread, revised and renumbered. I'm sorry for the confusion.

author: t1d
author_rank: Super Contributor
timestamp: September 13, 2018, 06:56:21 am
content: Quote from: JS on September 11, 2018, 07:14:18 amI have been thinking through your solution. I believe I understand your instructions up to "and the diodes in the feedback of each opamp." It sounds as if you are suggesting diodes in the feedback of op amps other than U1D (now know as U2B)? If so, which ones and why?For attenuation, how about injecting the signal, before Pot2? I would like adjustable attenuation, if this would work. If so, wouldn't the value of the 50 ohm resistor, R45, need to be adjusted? If so, to what value?Here is a drawing, of my understanding, so far... Notice that I make use of the existing 100K resistor; R21.Thanks, for getting me through this.

author: JS
author_rank: Frequent Contributor
timestamp: September 13, 2018, 08:10:24 am
content: The diode in your drawing seems fine but should be in parallel with the resistor, not in series.Then, all the opamps driving gates same thing but the diode in the other direction. This will hold all the opamps to getting saturated while the load is off (negative input) and recover much faster and with smaller wind up than if the diodes weren't there.The pot can be the attenuator. 100k summing resistor, 10k pot, 50Ω input, nothing needs to change there.JS

author: t1d
author_rank: Super Contributor
timestamp: September 13, 2018, 08:51:46 am
content: Hi, JS, Thanks, for your fast reply... Here is how I envision your instructions...I just want to double check... All the diodes are 2.5v zeners, even though the reference voltage is 2.5v. Correct?There is not a resistor, in the MOSFET driver op amp circuits... It is a capacitor... I put the zener in parallel, to the cap. Correct?I think we are almost there! Thank you, so much!You can't sleep, either, eh?

author: JS
author_rank: Frequent Contributor
timestamp: September 13, 2018, 09:48:18 am
content: Signal diodes, not zeners, all the rest seems correctJS

author: blackdog
author_rank: Frequent Contributor
timestamp: September 13, 2018, 10:41:38 am
content: Hi,Maybe is it is inspiring to look at this design, fast dummy load with a almost perfect puls response.A lot of importend info is already placed in the pictures.The main part.Power supply, van controler and simple puls generator.This is the link of my topic on the Dutch electronics website (use google translate )https://www.circuitsonline.net/forum/view/121338/1#highlight=load+dummyKind regards,Bram

author: t1d
author_rank: Super Contributor
timestamp: September 13, 2018, 01:41:31 pm
content: Quote from: JS on September 13, 2018, 09:48:18 amGreat JS! I am truly excited; thank you so much.Is a 1n4148 appropriate? Or, do you suggest something else?I will finish up the schematic and post a final edition.I would not have made it, without you. I appreciate you.

author: t1d
author_rank: Super Contributor
timestamp: September 13, 2018, 01:45:31 pm
content: Good information, Bram. Thank you, for participating.Is there an English translation button?And, please provide the two schematics in a downloadable file format, like pdf, or jpeg.

author: JS
author_rank: Frequent Contributor
timestamp: September 13, 2018, 05:16:33 pm
content: Quote from: t1d on September 13, 2018, 01:41:31 pmYes, 1N4148 are fine.JS

author: t1d
author_rank: Super Contributor
timestamp: September 14, 2018, 03:19:21 am
content: Thank you, JS, and all others, for your help, in creating the auxiliary input, for the Function Generator. Here is the completed schematic...

author: t1d
author_rank: Super Contributor
timestamp: September 14, 2018, 02:52:15 pm
content: JS,It has occurred to me that, as an auxiliary FG input is now available, there may not be need, for the on-board 330MHz FG. So, I relocated the aux input, to the controlling op amp input, via a break-before-make switch, and deleted the on-board FG circuitry. Would this work?Thanks.

author: JS
author_rank: Frequent Contributor
timestamp: September 15, 2018, 06:14:27 am
content: It will work, but it might still be useful for some quick check, if the opamp is integrated in the IC already... Also, if removing the oscilator, the 33k resistor should be changed to closer to 50k... 51k or 47k will do fine. (The obe to the non inverting input from the remaining opamp in the picture)JS

author: t1d
author_rank: Super Contributor
timestamp: September 15, 2018, 10:30:55 pm
content: Terrific, JS! I think we can mark the post as "solved," now...Thank you, so much, for all your wonderful help. You have shared your time, effort and expertise so graciously. I appreciate you!

author: JS
author_rank: Frequent Contributor
timestamp: September 16, 2018, 01:21:50 am
content: Seems fine for me, did you placed the diodes in every other opamp? Otherwise they will still be in saturation and will take a while to recover after the input goes below zero.JS

author: t1d
author_rank: Super Contributor
timestamp: September 16, 2018, 02:44:54 am
content: Hi, JS,Yes, Sir, for each one, as you had instructed. See the pfd, at post #32.Thank you.

author: JS
author_rank: Frequent Contributor
timestamp: September 16, 2018, 04:32:53 am
content: Well, I wait for the full docs then, or a PCB if you end with an spare one or two... I'd be willing to help with the span of it as well, I made a DC load recently but a bit whimpy and lacks the external input or the dynamic capability FWIW. It does work in CV though, which is nice for testing CC supplies, or current limits.JSJS

author: t1d
author_rank: Super Contributor
timestamp: September 16, 2018, 07:13:58 am
content: Sure, JS, I would be glad to share any and all.I posted the completed KiCad files, for the original three versions, of Jay's design,which include his oscillator,on his thread.https://www.eevblog.com/forum/projects/dynamic-electronic-load-project/I will post the KiCad files, for our two hacks which inject a function generator signal... one with Jay's original oscillator in place... and the other being my preference of the circuit without the original oscillator. But, I am too tired to do that tonight... I will have to round up the custom libraries, and such, and zip it up. Tomorrow, I imagine...I am sorry, but I do not know what you intend, by"I'd be willing to help with the span of it as well..."I am sending you a pm, to discuss the PCBs...

author: t1d
author_rank: Super Contributor
timestamp: September 16, 2018, 11:41:21 am
content: I bread-boarded the control circuit, earlier in the evening. I could not sleep, so I did a power-on test. Using a LM741 op amp, from the op amps that I have on hand, I was able to maintain a very acceptable square wave, to 5000KHz.I don't know the correct term, but there was "echoing." However, the shape was not greatly deformed.Interestingly, at lower frequencies, there was a prominent spike, at the top of the rising edge. It disappeared, the faster I tuned it. I would have thought that it would have appeared, at faster speeds, not slower.

author: JS
author_rank: Frequent Contributor
timestamp: September 16, 2018, 12:46:52 pm
content: I could help drawing the pcbs, that's what I meant.The spikes appear in fast edges, as you come closer to the freq limit the spikes are seen from closer and it can look as the echoing you mention (reflections?) which would need to be traced out but improper termination of wires is usually the peoblem, hence the suggestion for the 50Ω termination at the input. Something similar should be done at the resistor output but pretty hard to manage for the actual load connections, but anything there will be seen by the source, the load and the used meter so that's not as bad. Slowing down the design makes it less overshooty...JS

author: t1d
author_rank: Super Contributor
timestamp: September 17, 2018, 03:52:57 am
content: Here are the KiCad files, for the Function Generator Injector versions of Jay_Diddy_B’s ingenious Dynamic Electronic Load design. Find Jay’s Thread, herehttps://www.eevblog.com/forum/projects/dynamic-electronic-load-project/KiCad is a powerful, FREE program, to make schematics and board designs. Find it here:http://kicad-pcb.org/.It will be very easy, to create PCB boards, with the files.What Is includedCircuit development branched into two divisions; Jay’s original LT1013 Dual (Power) Supply model, which includes his oscillator section, and my model of the LT1013 Dual (Power) Supply, having Jay’s oscillator section removed.The schematics are ready for you to use, as is. You will only need to:- select your choice of model,- verify your choice of op amps and MOSFETs, (See following!)- select your components and- create your own PCB board design.Feel free to customize. Use components that you like, or have in stock. The selection of the component types, for the board, is done, with the CvPCB function, found on the schematic page. Whatever you plan to do, you will be miles ahead, using these files.A note on customization… Changes in components will effect performance; you need to know what you are doing, or get help. If you change the number of MOSFET nodes, you will need to calculate the new value, for their meter output resistors. If you want to use a different op amp, you will have to change the connections, to the new op amp’s pinout, asthe LT1013 does not have a common pinout.To change to a quad op amp having a common pinout, it might be easiest to go to Jay’s thread, download the LT1014 project files (Post #144) and add to it your choice of Function Generator Injector method. You will find other circuit variations there, too.The wattage, seen by the shunt resistors, can be spread over parallel resistors, but it does limit the accuracy. For accurate current shunts, one has to operate them at well below nominal power; at nominal power the self heating is usually too high and causes excessive change in the resistor value. The 0.1 Ohms shunts should operate at something like up to 1 A and thus 100 mW. Still it would make sense to choose resistors that are good for a 0.5 or 1 W power rating. 250 mW types are too small – even with just 100 mW used. So, the value of parallel shunt resistors equals 0.1 x number of parallel shunt resistor used.The value of the meter output resistor should be 50 ohms x number of output stages. For example, with four output stages use 200 ohm resistors.A Note To SMD UsersAll the resistors can be 1%. The cost of 1% versus 5% is minimal. Most parts can be 0603, 0805 or 1206 whatever you are comfortable working with. You need 2512 resistors for the shunts. The 2.2uF/100V should be 100V 1210 size.A Note To Non-KiCad UsersKiCad allows the selection of component footprints, regardless of their schematic symbol. 01x03 connectors, labeled as "Wire Pads," are used here, to represent the selection of Wire Pads, on the PCB board. This method enables the use of separate Control and MOSFET PCB boards. However, these connections should be hard wired. Because of high power draws, connectors should not be used, to connect boards, to MOSFETs. If a single, Control-MOSFET board is used, remove these pads, from the circuit.Use At Your Own RiskYou are free to make any and all use, of the files. However, in doing so, you release all contributors and me from absolutely all liability. I am not an electrical engineer. I do not guarantee that there are no mistakes. You must verify absolutely everything, for yourself. I did not design the operational circuit.

author: t1d
author_rank: Super Contributor
timestamp: September 17, 2018, 04:00:55 am
content: I would appreciate it, if someone would download the KiCad files, verify that they operate properly and post back, here, to let me know. Thank you, for this help.

author: t1d
author_rank: Super Contributor
timestamp: September 22, 2018, 04:20:18 am
content: The complete project release can be found here:https://www.eevblog.com/forum/projects/electronic-load-project-ltv171-irfp250-with-kicad-files/msg1840739/#msg1840739