"Purple" PCB Mini Spot Welder
ฝัง
- เผยแพร่เมื่อ 6 ม.ค. 2023
- More in depth details and suggested mod for this "Purple" PCB Mini Spot Welder!
Please be aware that an updated (thankfully - someone at the dev dep must be paying attention to my channel!;) version of the Purple Mini Spot Welder is being shipped as of beginning ofJanuary 2024 and has the Opto Decoupling mod already applied so you don't need to modify anything on this version. You can tell if you have the updated version by the lack of the trace going from the opto across the silk screen to the positive contact - the updated version lacks this and has an additional trace on the back side of the pcb going towards the 470uF decoupling cap near the diode where it connects. Check out the community section for more detailed pics of the 2 boards.
If you like and appreciate my content, feel free to like and subscribe and why not offer me a beer @ my paypal: icecool.daiceman@gmail.com - cheers!
FYI In the video I list the necessary components and the text omits the 1N4148 or 1N400x diode (but I mention is several times).
Aliexpress link (highly suggested to purchase model with plexiglass casing):
www.aliexpress.com/item/10050... - วิทยาศาสตร์และเทคโนโลยี
![จังหวะนี้ - เม้ก อภิสิทธิ์ [ Official MV ] จอนนี่มิวสิค](http://i.ytimg.com/vi/4gQRZCkRyiU/mqdefault.jpg)
I fried three of those cheap alliexpress spot welders before I saw this video. Just finished the mod on the fourth one and it worked! Thank you for the tutorial.
This mod fixed my weak weldings, very well explained. Thank you.
I hate to leave comments this often, but I figured it out, I reflowed solder on my mosfets, I didn't notice your at first but I saw other people doing this, and noticed you mention it near the end of your video. Thanks for the help I can start welding now.
Thank you man, I have added 5 mosfets on the backside and now will do this mod.
Excellent, I am making one of those up and will do this mod, most appreciated.
thank you very much, the welder is a lot better now
This one is a great spot Welder. I did so many welds and it didn't break. Under voltage 10.00v and over voltage 15v, it didn't break. Over 1400 cells x 4= 5600 welds. It only cost $20us on ebay.
Blindly following this with a distant understanding about why I'm doing it. Stayed up most the night ripping various things apart looking for a resister and a diode. I have beefed up the tracks with some copper. Works well, Thanks for the in put, I would have never figured this out. It's a much more peaceful experience with out the buzzer/siren as well. Good work.
If you look to the upper right of the “gear” display you will see a little black smd diode with the marking “M7” on it. Feeding that diode is a via coming from the positive, on the underside of the board. Battery positive goes through that diode and charges the 470uf cap to the right of the diode before being fed into the “78L05” 5V regulator. All the logic on the board is receiving power through that diode/cap buffer.
They are there for the purpose of being a small power “reservoir” that the regulator can continue drawing 12v from when the battery voltage sags during the few milliseconds that the weld is happening. The diode allows the cap to be charged but won’t allow that charge to be pulled back out in the opposite direction to the (very) temporary lower sagging voltage flowing out into the weld, creating a voltage buffer.
The battery sags in a dead-short (weld) because it’s stored energy content inside that create the “pressure” of voltage are being allowed to flow with almost no restriction of resistance, causing this internal “pressure” (voltage) to flow out faster than the the internal structure of the battery cells can sustain. This is the internal resistance of your battery becoming apparent when it’s used in a short-circuit situation for spot-welding.
All you did by preforming this mod is exactly the same thing that’s already on the logic power input, only difference is you did it on the other side of the octocoupler (isolated circuit that sends power to the gates of the mosfet, triggered by octo-coupler) for the same purpose. To act as a power “reservoir” for the mosfet-drive circuit. When the sag happens during the weld, now the gates will still see the full turn-on voltage as they are feeding from the capacitor you installed, that will not discharge for the same reason as the other. Because it’s being fed through the diode. The resistor is there simply because that cap can charge so quickly that it can burn the diode, and adding the resister limits the recharge flow into the cap to a tolerance that the diode can withstand.
@@markb1911 Thanks for that comprehensive info. I understood it stops the voltage sag and in turn more consistent voltage supply. But it's great to know why. I get caps. but diods, fets, resistors, logic input, lots to learn about circuit boards. Thanks again for the explanation. :)
@@nickdarling5557 Welcome! yea there’s some terminology but each of those components individually are somewhat simple in function. (it doesn’t seem like it though) I like to think of circuits as many individual components in cooperation. I just received this board and did the mod as well.
I don't even have one of this spot welders but I bought one yesterday from temu, it was on sale for only 11 bucks so I had to grab it.
For what I understand this is what is being corrected...
The gate on the mosfets are drawing 12v power directly from the positive side, they go from the positive, through the optocopler, through the resistor in to the gates.
When the gates open, mosfet discharge through the negative since it's a short anyways.
once the mosfet discharge you're basically slurping all the power out the battery leaving a sag in the system, this sag is most prominent at the gates because it's the weakest point of this circuit, instead of being supplied with the correct 12v to keep the gate open the sag drops the voltage down to 6v which is half the mount it requires to drain correctly.
full power is still running through this circuit at this miliseconds and that's enough to blow up the gate, since the gate is half way open but full power is being drawn.
What your doing with the correction is storing power on the capacitor, so when the sag happens, the mosfet still has enough power to deliver and keep full gate open and correct drainage 12v.
The resistor is to trickle charge the capacitor so it doesn't get full power extending its longevity after system comes back up and the diode is to keep the power flowing in that direction otherwise it'll drain through the positive with the rest of the discharge and the capacitor will be there doing nothing.
At least that's what I got out of it, you can even see the charts Luka is proving from the oscilloscope, how the gate is dropping down to 6v on discharge leaving it vulnerable, I felt in love with this hobby 10 years ago and I am barely starting to understand it now, sometimes I want to just forget about it and move on and then I watch someone doing a repair on TH-cam and I can't help but to sit and watch for 30 minutes how they find the shorted capacitor.
Watch this video again after reading this post and you'll understand exactly what is happening, the optocopler is the switch being governed by the chip set, chip set, sends the signal when it detects a short and the magic happens 🎉
@@letylaborin8523 Yes, your description of what the mod is doing is fundamentally accurate, it acts as a power “reservoir” with a resistor to limit it’s “fill” rate, to keep it from “fillling” so fast that it overheats and destroys the complimentary diode which is essential block the capacitor from discharging into the load, as during the weld there is temporary a lower voltage potential due to the battery being discharged at a faster rate than the internal structure is realistically designed for, and the inherent internal resistance in this structure acts like a resistor within the battery, causing heat and voltage drop. This is apparent here because of the “extreme” short-circuit nature of spot welding.
Mosfets function a bit differently than what you describe, and the best way I can think to describe it is a faucet tap. They are acting as a “valve” in line (series) on the negative battery lead, & in this configuration, breaking the circuit when they are off. The gate is like the twist valve on a water faucet that gets twisted open with a positive voltage is applied to it relative to it’s source. This positive voltage on the gate creates an electron “bridge” between the drain and source of the fet, allowing current to flow between them.
however, this faucet (mosfet) needs to be twisted open, and then shut very rapidly, so that most of the weld duration happens with the faucet (mosfet) fully open because it acts like a resistor in the time period when opening and closing. (that’s how it allows & clamps the current off, in this case by quickly increasing and decreasing resistance). If the mosfet is opened and closed slowly, it is generating large amounts of heat resisting current during the opening and closing time-duration. The amount of current used for spot welding is such that, if the mosfet isn’t switched fast enough, the heat generated from being in that “in between” state is so great that it will completely burn up and blow out the structure of the mosfet. There is a channel called Engineering Explained here on YT that has an excellent explanation video about how mosfets work, probably better than I can explain it.
Hello Luca: Thank you for all of the work that you’ve been putting into explaining the working of these welders. The new boards no longer have the trace going from the positive rail to the optocoupler. The leg on the optocoupler is tied to the positive of the 470 uf capacitor that is on the board but seems to be isolated from the positive rail. My question, if you are able to answer it is, is the mod still necessary? Is there still a benefit to adding the extra capacitor and also the resistor-diode combination to the optocoupler? I have pictures of the new boards but not sure how to get them to you.
Hi, you can send them to my email in the info of my channel or post them somewhere - will check the board and see. If they have modified it the decoupling mod shouldn't be necessary - maybe the inrush current limiting resistitor, but would need to see a closeup of the front and back of the board.
Hello , thank you for your reply. I thought highly of the bettery supplier but perhaps you are right about specs. I am using xt90 on shortened leads. I will try another battery
Hi Luca, great review but I have just purchased a "purple" welder from Ali and it seems they have changed the circuit again. The revised board has the opto leg you have added the mod to now connected to the 470uF cap on the input side. Have you had one of these later boards and if so does it also need modding? The new PCB has 12V A3 Mash Welder VO and 230828 printed on the reverse.
Hi Harry, thanks for the update - no I haven't seen this new revision. If you want you can take some close ups front and back and send them to my email. Cheers!
Thanks so much Luca! I bought the same board a while ago last year watching someone video and stumbled on your analysis and mods videos for that board. I will perform the mods, test the board and provide feedback on its performance. What do you think about using a IR20xx dedicated gate MOSFET driver, would it be more stable in terms of turn on/off time? Also, do you think the MOSFET would benefit from adding a heat sink?
Hi Francois, a dedicated driver is always better (lightyears) as you drop the on time to the nanosecond range instead of microseconds as you can see from the scpe shots on these devices. Regarding the heat sink, if you use the board so intensively that the FETs get that hot, a heatsink will be useful but then it's not really the board for you. Keep in mind that if you use it for say a few dozen welds the FETs will get warm, but shouldn't be allowed to get so hot you can't touch them as if this is the case, your electrodes and wires would also be that hot so you really need to wait for everything to cool down again. If you use this normally you will notice that everything more or less heats up at the same pace, wires, electrodes and FETs as the material is not great (aluminum core cables) and lossy by design. You really shouldn't need a heatsink in an average non intensive use. Adding one when the FETs are lukewarm really doesn't help (and they should stay more or less warm to the touch in a normal scenario, certainly not burning hot).
@@Luca_Techy Thank you
Like always very good job , Grazie Lu'
I have the same unit. I just did several thousands of spots weld without any issue as is. I made a video
amazing work. thank you.
Great info here, and in your other videos. Thank you for taking the time to share! This welder can really weld with the mods & reflow.
I was considering fully removing the buzzer from hell on another one, and placing this mod’s components in the space it leaves absent. That way it’s less crowded around the outputs, allowing my full-sized leads to be installed.
Which leads me to a question: Would the increased inductance from using 2ft long leads, 8mm in diameter, pose an issue here? & could the effects from the increased inductance be mitigated by adding a fly-back diode to the power source?
Thanks again for the helpful videos!
Hi, a TVS diode is always a good addition to these kinds of setups, especially when you start overdriving the original design so yes putting one (or two) across and near the FETs is good. Increasing the leads to 2 feet / 66cms and the diameter section can potentially lead to an increased Transient depending on the quality thus conductivity of the cable (pure copper vs aluminum) as there may be an even lower resistance than with the original cables, plus more length, and depending how the cables are intertwined, can lead to different transients. In general, all these high power, short pulse designs should include a 15V TVS diode(s) placed near the FETs.
@@Luca_Techy Thank you for the informative reply. It is surprising to me that the majority of these sub-$20 spot welders sold online do not include a TVS diode, at the least. After installing a 5KP13A diode across the outputs (from FET drain to the battery positive input lug terminal) on this welder, (with gate decoupling mod) the FETs don’t become nearly as warm as they did before the diode.
I will try and capture the output pulse from FET drains on the scope soon so I can see if/how much difference the diode is making with the possible transients associated with switching these high-current pulses. Thanks again!
Great explanation, thanks for the video
Anybody could give a hint if it would be possible to extend this spot welder to control the weld with a foot pedal switch?
You would need a hardware mod, theoretically cutting the autodetect trace and wiring to a pedal, this was you would trigger the weld through the pedal with the same delay as before. I think it's doable but I would need to check the circuit better to see where to cut and wire the foot switch.
after 8 months are you still using it and have you used it much? would you recommend replacing the FETs prior to use? all the best and thanks for the knowledge you are sharing, thanks.
I'm not using the welders lately, I haven't had the need to make new packs (luckily)! I've used mostly the Malectrics one. Regarding the FET replacement well use the ones u get then if you blow more than 1 then you're better off replacing them all with a new selected batch from a known source.
Buen mod, yo lo uso con 2 super cap 3000F 2.8v en serie y no tengo problemas sin la modificación, le he puesto 5 mosfets mas detrás y funciona muy bien, supongoque esta modificacion solo es en caso de usar baterías lipo o de coche
Por assicurar correcto voltage por los Gates si la batteria es problematica en general.
Ola Francisco. Dijiste que utilizas dos super caps en seria para sustituir la batería LIPO que todos utilizamos, y esas funcionan bien sin otras modificaciones? Correcta me si me equivoco. Tambien, porque los pusiste en seria en cambio de paralelo? Doblas el voltage para que Vds sea mas lineal despues de 3.5V.. correcto? Gracias por ayudar me entender lo.
I just got a purple welder in. The new one no longer has a trace connecting the positive rail to the bottom left corner of the opticoupler. Other than that my board looks identical. Should I be able to connect my positive side of my capacitor directly to the opticoupler? I’ve taken a continuity test from positive rail to all 4 parts of the opticoupler and It doesn’t go directly up to it.
You have the new revision then so you don't need the decoupling mod as the opto is powered by the 470uF cap from the regulator circuit. There's more info in the community section of my channel and other comments.
Hi, thanks for the vid.
I'm tempted to get this purple one instead of the new Rev0, given the issues with it.
Would this one be able to support 850A from AGM battery in combintation with very short pulses (2-4ms), or that's pushing the luck too much? :)
Also when the fets fail short circuit, that puts full current to the welding terminals, burning the user and making holes into the welded cell, or the fet just explodes too quickly for it to happen?
850CCAs can be overkill if this value is real - maybe extend the power leads by doubling their length with the same gauge. When a FET shorts there are 2 possibilities, one the FET fails and yields a hard short and you risk burning a hole in the battery or strip (most common) or the FET literally explodes and "opens up" leaving no current flow - but this is very rare honestly and most of the time you get a hard short. I suggest you check my latest FAQ video for all the details!
@@Luca_Techy Thanks for reply. Yes, I checked the FAQ quite literally after that comment :)
Ended up purchasing Wise Maple version, which seems to be the best (has tvs, actual fet driver, 4 fets instead of 5 so less issues with matching, only needs inrush resistor).
HeyLuca
Unfortunately I blew up one of the gates .. Saw a puff of smoke and then she was hot hot as far as the curtain I watched a guy repair the blown gate and he did what you have done to the purple one..where can I find a replacement part o parts. I have been listening to your expert advice and you have to match the voltage,I think that is what you said.
Can this device work without the one gate.just curious I have just started this new and interesting field . Wish I had been interduced many years ago. If you can spare a few minutes and give me some feedback I’d appreciate it . One more question,where can one find scrap electronics for those gates I can’t think of devices that would have them .that for your detailed videos very helpful.
Hi John, first remove the broken FET and check that the short has gone - check my lamp test video (in the playlist) on how to verify that the welder is operating correctly. You may or may not have another shorted FET - that's why you need to verify it. You can do this with a tester or if using the lamp method as I explain. You can use the welder without one FET, it will work just avoid overdriving it once you have done the indicated decoupling mod. The FETs should to be always replaced in identical batches so it's better to just remove the shorted one and use the rest instead of only replacing one with one from another batch. FETs should be purchased in bactches - u may find some used ones in large UPS or switching power supplies but they may not be rated for the current, better get the identical ones as they would also match the pcb pad layout.
This mod will be beneficial no matter what as the "driver" solution is so bad, but a factor that seems to be overlooked is that we should *not* be connecting the positive welding tip to the output terminal on this welding module. The tip should instead be connected to the *input* terminal along with the battery input.
This avoids running the full current across the PCB, causing less voltage drop to the gates. The voltage will still sag depending upon the cabling and battery, so it's still worthwhile to do the mod described in this video to preserve your MOSFETs and improve performance.
Correct me if I'm wrong, but the only reason that I see to use the existing output terminal is to orient the cabling for better usability in some layouts. However, moving the positive tip to the input side might improve usability depending upon how things are positioned in your workspace.
Hi, yes the positive "contact extension" on the circuit board is only for ease of wiring orientation, it is not beneficial to the pcb as all the current passes through the copper track as it is simply a bridge. In fact I usually screw the 2 positive terminals together on the same hole where I can. You could actually run a direct positive spot terminal lead from the + of the battery and add a second positive wire (any thin normal wire) to just power the welder logic which only bridges the negative side (N-MOS) and needs the + only for the MCU and triggering the FETs. This will not prevent a voltage sag on the logic board though as this depends directly on the battery quality - however if you have a correct decoupling cap on the logic power then the sag won't affect it for that brief pulse. If you have a poor battery you will simply not get a good weld or no weld at all, but the FETs will be safe(r) as properly triggered.
Is this better than the red one
can we put led diode instead of buzzer ?
Please tell me the optimum specifications (voltage, capacity, maximum current) of the lipo battery that can be used as the power supply for this Mini Spot Welder.
Check my latest video!
Luca, Can I use a 33 Ohm resistor ? I have some military spec resistors (black coating) with value of 33 Ohms 5% tolerance. measure with volt meter i get 33.5 ohms
Yes no problem, any value from 15 to 50 or so will do fine.
Okay, so I just bought this mini-spot welder from Allie Express.. if I make these suggested modifications, how long will this spot welder last me? Or should I simply return this?
I understand that you are using a Lipo Battery. I would like to use a car battery when this thing arrives.. that way.. if this doesn't work, I can atleast put the car battery in my vehicle and get some use out of it.. what lead acid battery would you reccommend?
That depends on what your car manufacturer suggests - if it's a petrol engine the batteries are usually 45Ah which is fine for the mini spot welders. If you apply the suggested decoupling mod you will certainly improve Gate response thus reduce the riak of stressing the FETs. Of course it all depends on the maximum current and weld time and strip thickness u want to weld. I suggest you check my latest FAQs video which should answer most of not all of your questions.
Hello I have modified my purple/pink spotwelder and I am having problems with getting it to weld. I am using a 3s 60c constant 95c burst. to weld .1 strip I need a setting of 40 . any ideas would be appreciated.
Hi, are you 100% sure your LiPo pack is really 60C? Many LiPo packs are way underrated - either that or you have extra losses somewhere on the connectors (I suppose you are using XT60 or 90). Try another pack if you have one or a car battery (always start from 5ms).
Thanks for the video and mod instructions. What is the minimum mAh battery that can be used? Is like a 2200mAh 3S or 4S acceptable. And would using a too low mAh battery risk destroying MOSFETS, or would it just output too little Amps or something? And is the LIPO batteries power leads thick enough, they usually dont have especially thick power leads.
Actually more important is the C rate of your LiPo battery, it should be rated over 50C and be at least 2000mAh so if your pack is at least 50C then it's fine (it's the current that welds, not the voltage). Also I would stick with 3S as 4S can be pushing the limit and actually doesn't give you major benefits over a good 3S with enough C and the risk of blowing FETs (overdriving) increases. If the pack is properly constructed and decent quality the leads and plug (XT60 or XT90) will be thick enough - you don't have to modify them. If your pack is underrated then you risk destroying FETs too, if the voltage drops low enough and for long enough and you increase weld time drastically trying to compensate for the weak welds (typical example of how users destroy FETs). Of course a dead battery won't have the power to destroy FETs, but then again you won't be able to weld at all. Please take some time to review my other videos as I explain a lot of the issues in detail (the criticalities are common to all these spot welders).
@@Luca_Techy Thanks for your answer. So would a 3S 5200mAh *80C* LIPO be a too high C rating? The other batteries with lower C ratings that i found have 12 AWG battery leads, and according to the "manual" one should use at least 6mm2 leads (10 AWG)? Is it acceptable with a 80C battery?
It will do, consider 80C the "best case scenario" - usually it's less. In any case always start from a low ms (under 5) when testing and go up.
@@Luca_Techy Sorry to ask you again, but the 3S 5200mAh 80C battery i received turned out to have 12AWG leads even though the picture showed 10AWG leads. So do i dare to use this battery with 12AWG leads for spot welding, or should i return it? Thanks.
I don't think it will be a problem, the cables of the welder should drop enough voltage to reduce the peak current.
what is the purpose of the diode? maybe no diode? Only resistor and capacitor?
The diode prevents the capacitor reverse discharging towards the battery when it's voltage drops (6 volts). Without it the cap is pointless in this application.
Super Video. Super erklärt.
Mich würde interessieren, ob man den bifrc spot welder auch modden könnte.
Sry for German but my english is not so good .
Ich habe die bifrc nie getestet - ich habe es gestelt aber nicht erhalten... es ist wahrscheinlich möglich zu ändern.
So is this thing any good? I have already bought 5 spot welders off amazon and they all blew the mosfets
It works ok (once you mod it) but as stated so many times again these mini spot welders are not to be overdriven (exceed .20mm) as they are not designed to withstand large TVS and extreme peaks, the FETs will fail if you overdrive them. If you need something more beefy get a more professional welder such as the Malectrics which I reviewed or Kweld. Check out also my FAQ video for more info.
Luca,
Thanks for your videos.
Why do the instructions suggest up to 100 AH car battery, but only if old, and not over 60 AH if new? I wouldn't think AH would affect performance.
I did the mod, but may have damaged mine with a motorcycle battery. I am using a car battery now, but I only get a very weak weld with the setting on 99.
Hi Brad, it's a simple method of imposing a current limit: a 100Ah Lead acid "several years old" car battery if still in working order (capable of starting an engine) will delivery less "CCAs" or Cold Cranking Amps than when it was new (15-30% less) due to higher internal resistance (due to unavoidable electrode sulfation on the ong run) -- or in the ballpark range of a new 60Ah battery, meaning around 150-200 peak Amps for a brief amount of time, which is the current limit of all "mini" spot welders. This is also why the instructions (somtimes undecypherable) ask not to shorten the provided power leads or replace them. It may seem all "lossy" but that's the whole point: if you don't have those little resistive losses introduced by the (cheap) long cables and rated battery the peak current delivered in the first few milliseconds will destroy the FETs (usually one fails - the most performing). You can't really avoid this, the only way is to LIMIT the current with resistance *or* have a much beefier setup with perfectly balanced FETs, TVS diodes etc but then you will have a minimum 150$ price tag for such a device (unless you build it yourself). You just cannot ask such a "cheap" design to deliver more current, it will simply fail. Some people are lucky to get better matched FETs and this helps to avoid the blown FET syndrome, but shortening the leads and hooking up a gigantic battery will destroy it. Similarly hooking up a very weak battery and "over timing" the weld (>40ms) because it can't perform will stress (overheat) the FETs but if the Gate drive is solid, they shouldn't fail so easily. You should stay in that operational range with the rated battery and max weld thickness of .2mm with max weld time of 30ms else you risk blowing FETs because something is not performing correctly.
@@Luca_Techy Thanks again for your time.
I have a 60AH, 650CCA car battery that is about 6 months old. I want to use this because I would prefer not to have to buy more items.
If I aim for 150 amps (as you mentioned above), can I use a 0.08 ohm 1W resistor to limit the current?
V=IR. V=12. I=150
R = 0.08
P=VI.
P= 0.96W
Thanks.
@@bradg7701 You would actually have to "drop" or limit 500Amps in theory so that's the ball park value with V=12 but this is all theoretical as there will be more voltage drop due to other inefficiencies so that resistance value should be even lower (probably half). In practical terms you would just need a bit longer cables if they were real copper: the ones provided are actually aluminum core so they have a rather high resistance - you could either extend the power lines by a few inches or just use it as is starting from 2ms upwards and see how that goes. Someone used jumper cables directly to extend the power line but that was with a 110Ah battery from a diesel engine. I think you should be ok just powering it with your 60Ah battery considering the losses, just start from a low ms setting.
@@Luca_Techy Thanks for your help.
I was previously using jumper cables from my car and this was causing the problem. I imagined those big wires would have little resistance, but I guess the clips etc caused a lot of resistance. I tried some other shorter cables, but even these didn't work.
Eventually, I connected the unit straight to the battery and it worked at about 6ms.
Oddly, one side welds better than the other. Maybe I need to push harder.
Thanks again.
@@bradg7701 As you see, any additonal resistance in the circuit even if small will impact the peak current necessary for the weld.
Great mode!!!
Can we install additional FETs in the back side to improve the power of the welder so we can go to thicker welds like 0.3mm? Also does it help in the longevity of the welder?
You can install them but the lack of a proper driver and matched FETs will introduce additional variables and potential problems as explained which won't necessarily improve the performance. It's up to you if you want to spend the extra money, personally I wouldn't and keep the setup for .2mm unless you modify and add a proper driver (and matched FETs).
I just got this board and it works great right out of the box (using .120 nickel and a 12V 12Ah lead acid battery). Now I am preparing to make the mod in this video and I see my board is slightly different. There is no circuit trace that meanders from the OUT+ pad to the optocoupler. Instead, pin 4 of the optocoupler is connected to the 78L05 voltage regulator Vin, which has 11.8V on it when powered by the 12.5V battery. Not sure where else this 11.8V goes, or where it comes from. So is this a different version of the board? Newer? Older? Its labelled KEKK, like many others, and seems to have all the same components. I've looked at images from dozens of vendors selling this board and all have that trace from OUT+ to optocoupler pin 4. Even the image from the Amazon vendor that I bought it from. But not mine.
You have the updated revision (they noticed the error and fixed it thankfully). You don't need to apply any mod to this version luckily.
Thanks Luca. That's the answer I was hoping for! I did beef up the MOSFET pin solder and the bus bar traces.
gr8 video thanks
Very good video. You have 209 FETS, I have 228. Do this mod apply to 228 also?
Yes it applies to all FETs conceptually, the correct GATE drive Voltage must be assured.
@@Luca_Techy thanks for the answer. My mod th-cam.com/video/UTXGsaH93zQ/w-d-xo.html
Thanks for the info. I pretty sure this is the one I ordered.
How does it weld?
Based on my early testing (post mod) it appears to yield very good welds on low time settings (I get great welds under 10ms on .1-.12mm strips). It appears to perform as the Wise Maple and slightly better than the modded BK/Bl series and just as good (if not better) as the latest New Rev 0 (with mod) regarding the weld result. I still need to do some more stress testing as I've only reached 15ms (which is plenty!) to see if it's stable.
@@Luca_Techy what size battery may I ask?
@@joshkelly3743 I always use a fully charged Lipo 3S 5000mAh 50C, specs are also in the video!
Hi Luca, i did your mod and it was working beautifully. At some point it started burning holes in my nickel strips, 0,15mm. Now its real weak and it wont weld very good at all, it depends though but its far from consistent. Are my fets blown? how could i check this? Thank you!
I found your video with the lamp test! smart. Result: when powered on, the first pulse is weak. As soon as i weld quickly after the other, the pulses are strong. Maybe tthe added capacitor is weak/bad? What causes this?
My guess: the capacitor is weak. i will replace or add, and update.
but then still, why burn holes every now and then? Help! 😄😄
Do the 12V lamp test, check to see if your FETs are triggering correctly or you have a short. You can find how in the video I made about it in my playlist. Usually when u have a shorted FET as soon as you contact the strip it will burn a hole as it's dumping the battery current directly onto the strip uncontrollably.
Thanjk you Luca! i think the fets are fine but welds are not cvonsistent, see the comment (copy paste): I found your video with the lamp test! smart. Result: when powered on, the first pulse is weak. As soon as i weld quickly after the other, the pulses are strong. Maybe tthe added capacitor is weak/bad? What causes this? im going to upgrade the capacitor anyways
@@Luca_Techy
If you connect two batteries in series, meaning 24 volts, and turn it on with another source, and use the negative pole across the board, will it work? Will the current on the board decrease? Will it work or will it burn? I know the higher the voltage, the lighter the current.
No it doesn't really work like that: Ohm's law states that given a fixed resistance (R) the ratio between Voltage (V) and Current (I) remains constant (V=I*R thus R=V/I) so given that the spot weld has a Resistance which is practically fixed (some milliohm plus the length of your cables and FET losses) the higher the Voltage means the higher the current. This means that if you increase the voltage you would get explosive overcurrent (if your batteries are capable of it). The concept of these portable spot welders is to have a compact and powerful power source (lipo battery) with just enough Voltage to overcome the resistive losses and still deliver enough current to the weld (200-600Amps). Professional industrial welders actually have lower voltages (max a couple of volts) but much higher currents due to the much thicker and conductive cables and electrodes in use. I hope this explains it.
Can I add a capacitor at the outlet with a value of 25 volts 2500f, does that help? Is there a solution to prevent the MOSFET from being destroyed?
@@user-Majdy a large capacitor bank (several hundred Farads) would be better if you have a weak power source - but this won't prevent the FETs blowing if you overdrive them. FETs blow for several reasons, improper Gate drive, slow switch on or off, overcurrent and reverse transient voltage peaks across Drain Sourse or Gate. Also FET unbalance when you have several FETs in parallel which leads to overdriving one more than others. Lastly, thermal breakdown. In this specific application the problems are improper Gate drive, TVS and overcurrent. As you see, it's not that simple. Basically to avoid blowing your FETs you need to consider all of the above, staying within operational limits (don't overdrive).
I have destroyed mosfets in this "purple" welder. I was using 12V 62Ah lead accid battery with internal resistance 8mohm. I set to "20" and i was traing to weld 0.2mm nicklel strip. And one mosfet have burned and all other are also not working. what was the cause of the damage do you think? the rest of board is probalby fine because the voltage is showing to the gate of the mosfets when welding
Most probably overcurrent and unbalanced FETs. Also without the decouoling mod the voltage may have dropped enough to no saturate the gates. 20ms is a lot for this welder, especially if using large batteries. Always stary from 5ms and go up. Also I don't recommend using .2mm with these welders unless you have balanced fets.
@@Luca_Techy i was starting from 1 to 15 and it was poor welding. And then set to 20
How balance fets?
@@radekzmazur3389 That's the thing that should be done during assembly in production, not by the end user!
Salut je viens de regarder ta video j aurais du la voir plus tot je viens de cramer cette soudeuse au bout de 4 point😅 mosfet cramé en mettant a 90 je commandes des mosfet et je vais egalement faire ta modif car la pour mes test j ai utiliser une batterie de moto neuve mais la tension a du trop chutée lors de la soudure merci pour toute ces precision
Luca IF replace ALL the IRL40SC209 mosfets on my board and replace with the IRL40SC228s will the board be ok as far as working with the mod and with the other parts on board or do I need to beef up other components on the board too?
You can keep the driver setup as is.
@@Luca_Techy do you think replacing with RL40SC228 will be a waste of time or a good replacement.... I was reading some people had done this and thought id ask for your opinion/advice..
Most probably the issue is that the supplied FETs on these welders are low quality clones and not really matched (apart from a bad driver design). Replacing them with better quality matched FETs purchased from a reliable source is probably why they perform better, not just because they are more powerful. Keep this in mind. I will release a video soon where I talk about this.
@@Luca_Techythank you ill be looking for that new video
Getting these IRL40SC228, Trans MOSFET N-CH 40V 557A 7-Pin(6+Tab) D2PAK T/R (5 Items)
Brand: Infineon Technologies
What a great video. Thank you. If you would have to buy one now wich pcb or other type welder would you buy?
That depends, if you need to use it seldomly then any mini spot welder would do *with the suggested mods*, probably this purple one would do fine or the Wise Maple which needs practically no driver mod. However if you want to be more serious about spot welding and use it more consistently then I would spend the money for a more serious model like the Malectrics I reviewed some time ago.
P.S. Sorry for the late reply (I don't catch all notifications).
can you use a 12v 12ah ups/electric bicycle battery ???
I wouldn't suggest it as it depends on the pack's current limit and BM system and type of cells (I suppose 18650 LiIon) - use a dedicated 3S 5000mAh 50C+ LiPo pack or 45Ah car battery if you don't know it's exact characteristics, it's a safer solution.
There is another solution how to protect mosfets. Do not connect positive from battery to welder but positive dirrectly to electrode . Only negative from batttery is connected to spot welder. In addition, there is a DC power supply connected to welder
Yes that is an alternative as it also decouples by separating the positive lines. However it also makes things more cumbersome, as you need an additional battery (or PSU) for the "logic". The point of these mini spot welders is to be "portable" thus work with one power source. Unfortunately that *still* isn't enough to avoid destroying the FETs if you overdrive the welder as it has no reverse transient voltage surge protection and the FETs are probably not always matched.
Radek, if I get this spot welder, I'm going with your idea. Just to be sure. :-) I have some 12V power supplies around just collecting dust. Do you think 12V/1A would be enough to power the board?
@@GargamelCZ i think yes. i have tested this spot welder with DC power supply. With 3 mOhm battery there is no problem to weld 0,5mm steel or 0.1cooper+0.1 steel
I increased the number of mosfets to 10. and eliminaded cable from battery to welder. battery Clamp is conneted directly to welder.
@@radekzmazur3389 Where did you get the mosfets from? Just generic Aliexpress buy? Or did you find some service providing matching FETs?
@@GargamelCZ but i am not shure if increesing number of mosfets helps something. With oryginal 5 mosfets you can have up to 2000Amps. With 10 you can have max 4000-5000 Amps .
Moded a new one, but it will not weld two pieces of nickle strip together runing off a old small car battery?
Probably not enough current from that old battery, try another.
@@Luca_Techy Sorted, I copied how the spot welder is connected to battery in this kit. Most be reason why this kit, for the same spot welder, comes with these terminals. Mine goes well now. th-cam.com/video/k7KJGsuu7M8/w-d-xo.html
So on this version, the MCU does not suffer confusion from the droop in
Power Supply voltage? Only the FET driver?
This version has a 470uF decoupling cap on the 3.3v regulator so the MCU is decoupled yes, only the optocoupler output junction is tied directly to V Batt which can drop.
@@Luca_Techy Ah yes, as I suspected! Thank you, sir, you are a
Fountain of Information......
I am planning to buy another of some version for a backup in the
event I "smoke" my current one. I think I'll stick with my plan to
make a "Mod Board" mounted behind the main board, It would
contain a FET driver chip(remove opto chip!), foot switch
interface(if needed), your cap/diode/resistor mod, and maybe
buzzer switch (on/off).
With a little work, these cheep boards can work really well.
Without some mods, they make great smoke bombs........
Thanks again, I look forward to your next installment in our
education program series!
@@Luca_Techy Thank you for the earlier reply; I have ordered one
of the purple boards. Since it will be 2->3 weeks to arrive, I have
started fiddling around with Eagle to design a Mod Board like I
mentioned in the previous comment. I'll be ready when it arrives!
One really simple fact I cannot find. That is the exact spacing of
the mounting holes. Suspect they are different from the Red Board,
but I'm clueless. Do you know where that info might be published?
My search engine puked up everything but that!
On a more interesting note, in one video you mentioned the fact that
all the FET gates are wired parallel with no individual series and pull
down resistors. Bad news as you suggested. So I am wondering about
a method to fix that. Since I will be using a FET Driver, it seems that
there could be (at least) two ways to approach that:
1) Have the FET Driver drive 5 series resistors & 5 pulldowns. Cut traces
to the gates (in static free enviourment!!!) and drive the FETs individually.
Lots of resistors, but a Mod Board would have TONS of room - even home
designed, etched, and stuffed with very "loose" design rules...
2) Simply use 5 FET Driver chips - one per FET. Crazy overkill for sure!
And maybe overload the MCU output driving 5 inputs to FET Drivers?
Of course, 5 chips would have slightly different prop delays - unmatched.
But with the lightning speed of these things (ns), I suspect no significant problem.
Do you have any ideas of an optimal way to drive the FETs individually?
Being retired, my time is cheep! (When I can get away from the darned
old tractor for a while)...........
@@dd_ranchtexas4501 If yuo check out my playlist there are schematics of the other Red Mini Spot welder (also REV0) boards I made available: you can see how they drive the FETs in a more proper way with a 30Ohm resistor in series with every Gate (but the more recent lack a proper FET driver). This is then all fed to the same push-pull driver. If you stay within 5 FETs with those characteristics you can use one single MCP1406/7 driver as it can handle the total capacitance of the combined gates - you needn't go for one driver per FET as we are switching just on and off every bunch of seconds, not the critical hundreds of KHZ in a switching PSU.
@@Luca_Techy Yes sir, 5 Drivers for 5 FETs are crazy overkill!!
Just another insane BidenMoment for me.....
I have all (I think) of your schematics of the Red boards. I used those
when I made the FET Driver mod board for my red board. It works
wonderfully well - zero problems. So I am focusing on my #1 choice
from my previous posting. One FET Driver with a series resistor and
a pull down for each FET; thus 10 resistors. I don't yet know the
exact dimensions of the PB(purple board), but clearly there are acres of
room on a board that is the external size listed in the ads for the PB.
Initial Quick & Dirty layout with Eagle CAD looks encouraging.
In another PB video, the author pushed it up to the point of sorta welding
a 0.3mm strip. And I think that was with the Opto Driver (Ugh!) for the gates. With a FET Driver chip, like the MCP14xx or TC44xx series, the
much faster switch times getting to high voltage and return to zero
should, I think keep the FETs cooler and less stressed. Even with my
new Ovonics 8A 80C 3S1P battery. The less time spent in the Linear
region, the better!
At least that is my S.W.A.G. (Scientific Wild Ass Guess)......
Gonna be a long 2-3 weeks waiting for delivery of the board. (-;
This board send continuosly pulse even if the pins don't touching ,or is activated by the touching of pin and send the pulse?
Because I don't understand how the mosfet is activated and how they are interrupted if you bypass the red wire (+)?(if i use a external wall power source)
This bord work like a timer with continuosly pulse when is powered?
I'm not sure I understand what you're asking: the board has a contact detect circuit which activates the FETs after a second or less you make contact with the terminals. If you find that it always welds or there is always current at the terminals then there is a shorted FET most probably. You can do the lamp test I show in my other video (check out the playlist) to check correct operation of the welder.
@@Luca_Techy ok perfect thanks very much
@@Luca_Techy i ask because i see another MOD where a guy bypass the PCB with the red wire of battery ,and for powered PCB use a external wall power source,this for prevent droping voltage on mosfet.
Yes I see, that is also possible but if you do the decoupling mod I show you really don't need an additional power source or external PSU for the logic. I get many questions regarding this and I see there is some confusion so I will try to make a video about these FAQs and reply to all and clear up some misconceptions.
@@Luca_Techy thanks 🤗
I have this spot welder. one thing anoying me, welding delay time is too short for me, is there any possible modification to connect foot switch ?
Yes you can cut the contact detect trace and wire a foot switch to it, it's not a difficult mod, just locate the contact detect trace and cut it and solder a switch between the side of the trace that goes to the mcu (not the one to the contact) and the other side to positive. The trace to cut is that small trace on the back side of the PCB that goes to the negative contact pad (side towards electrodes).
@@Luca_Techy thats the bigest problem. I have no idea where brake wire and put switch between it :)
@@mateuszmikolajczyk3185 I'll post a picture sometime later showing where to cut the trace.
that would be very kind
@@mateuszmikolajczyk3185 I have posted a pic in the community section with details on the mod. www.youtube.com/@Luca_Techy/community
Hello,if i have a Li-po 3 s 1500mah 100c it's enough?
That's not really enough - you need a minimum of 5000mAh 50C (250 Ah peak). Maybe it can weld depending on the quality but I suspect it will be very stressed on the long run.
Thanks a lot!
How would one add a trigger button to this board?
I think I mentioned this to someone else: you would need to do a hardware mod by interecepting the contact detect trace that goes to the MCU detect pin, cutting the trace and wiring the resistor divider (MCU side) to a footswitch and the other to the positive so that when you press the footswitch you emulate the contact (the detect circuit usually detects a positive voltage once the contact is made through a resistor divider to lower the voltage to the MCU input pin compatible level). Of course once the trace is cut, the auto weld won't work unless you bridge it (maybe add a switch acorss the trace cut).
@@Luca_Techy thank you!
Ciao Luca, potresti dirmi cortesemente se funziona con una 4s completamente carica? Quindi a 16,8v? O rischio di fare saltare qualcosa? Quale sarebbe il voltaggio massimo che può sopportare in sicurezza? Non ho capito una cosa nella modifica quale condensatore devo usare da 16v o da 24v? Grazie in anticipo
Ti consiglio di usare una buona 3s anche se qualcuno usa la 4s apparentemente senza problemi. L'elettronica non ha problemi usando una 4s perchè passa tutto dal regolatore (MCU, LED etc) e la tensione massima GS dei FET è cmq 20V però si rischia di eccedere la corrente impulsiva e quindi far saltare qualche FET se hai un pacco con C elevati (per es. un 5000mAh con oltre 60C). Dovresti in teoria prolungare i cavi di alimentazione per ridurre la corrente massima, ripeto dipende tutto moltissimo dalla qualità del pacco che usi. Per la modifica prima assicurati di avere la vecchia revisione perchè la nuova non ne ha bisogno (se vai nella parte community del canale ci sono le foto con le differenze tra le due). Nel caso, l'eletrolitico va bene sia da 16V che da 25V (se usi una 3S ovviamente).
Ciao Luca grazie veramente per la tua risposta. Vorrei provare ad usare una 4s. Quale condensatore dovrei usare?
Attualmente ho una 3s vecchia versione (ne ho 3) con batteria 6000mah 100c con awg 8 e cavi allungati dì 20cm
Insomma la saldatrice e' la vecchia versione con una batteria 3s e cavi allungati dì 20cm
Usane uno da 25V allora, 470uF bastano. Verifica la versione della tua basetta.
Ciao Luca perdonami, hai un link della nuova versione? Io ho trovato la Kekko k100 che ha dodici MOSFET sembra simile ma ha qualche differenza vorrei sapere se ha la modifica già inclusa
Purtroppo non ho un link sicuro dato che vengono inviate "a caso" queste versioni aggiornate (sai come lavorano) - l'unica è scrivere al merchant di mandare foto o richiedere info del prodotto, o in alternativa aspettare che qualcuno qui metta un link del merchant.
Prova a dare un occhio a questo (dalle foto la modifica è presente): www.aliexpress.com/item/1005005625936569.html
@@Luca_Techyno Luca nelle immagini vendo sempre la traccia che dall' opto va al positivo
Volevo dire Vedo e non vendo scusa
Hai ragione, scusa ma dal telefono non ci ho fatto caso! Le immagini però potrebbero non sempre essere veritiere (da quanto detto molti hanno ricevuto cmq la versione aggiornata).
Si è la vecchia versione ne ho tre già controllato grazie
Hi I have the same welder Can you tell me if I am safe using my drone lipo turnigy 2200 - 20-30C discharge (44-66Amps) in working condition with this welder without Modding? - I am not an expert. I would use other battery if necessary
Hi, your pack is not enough to weld properly, you also risk damaging it (it will swell up). You need a 3S 5000mAh 50C at least to get decent welds without stressing the LiPo cells (or if you have a 45Ah-60Ah AGM car battery in good working order you can use that too).
@@Luca_Techy gosh thanks for this info. I kind of knew about a proper High amperage battery but wasnt sure if it's enough.. you probabily saved me from disaster. I have to get an AGM then but prices are high. maybe better to go 5000mAh. i have to check the solutions.
@@Luca_Techy Tattu FunFly 3s 11.1V 1550mAh 100C XT60 - looks like it has 155A but will this be enough ?
I don't suggest a small pack with very high C - that's not appropriate for this application. You need at least a 3S 5000mAh pack starting from 50C upwards as I mentioned. Small packs with high C cost the same and are more likely to fail earlier than larger packs. This is due to the design of larger capacity LiPo cells which have more equivalent surface area to deliver high current and less critical im design. They are less prone to stress in these conditions. Without entering too many details just consider more capacity = less stress and less unbalancing over time.
@@Luca_Techy thanks so much for this valuable lesson. I will go 5000 up for lipo or good powerfull AGM or good used one in good working condition. One last question is it possible to go too powerfull with the power source (eg battery, lipo ) in instruction it says that for lead -acid or AGM the new battery can not exceed 45Ah.. and if it's more that I should consult their customer service and ask them for the current limiting method. Mine has Infineon MOS and sigle MOS tube is 400A max theoretical. 2000A for all 5xMOS
There is one thing guys you don’t seem to consider… Check the price of 1 mosfet from a reputable source (mouser,farnell,digikey - i know the more you buy the cheaper it gets but still…) and compare it to the price of 18eur for the entire pcb welding board… What I’m trying to say here is: maybe there is a certain model marked on the case of these FETs and that makes you refer to the relevant datasheet but how do you really know it performs like the datasheet tells you? It’s not the first time I found a lot of these chips are fake. For an example I’ve bought 4 step down converters based on ST power regulator - by datasheet of the ic chip the max voltage was 60V and I needed it for 58 so I thought- ok, it will do. (Chinese seller was saying though it’s up to 60V but they DON’t recommend more that 50V). So the datasheet says 60V but on the other hand it’s not that okay 😂. Anyways two of these boards blown instantaneously one after another at 58V. I’ve bought the same exact power regulator IC BUT from a reputable source (it cost with the shipping the same as 4 entire step down converter boards from china…) but it works since a year now absolutely perfectly!! So to summarise guys: with these Chinese stuff what you see is not always what you think it is… That’s why probably some of these welders are using 8,10, or even 12 fets and still cost pennies- MAGIC. They use lots of FETs probably because they are not what they are in reality in terms of specs. Just something to think about.
Hi, yes I mention this issue several times in my various videos when I also talk about the importance of FET matching. It's obvious there is a lack of matching and overall quality control plus the incognito of the originality of the FET itself. Just buying 5 FETs from a reputable source costs more than the whole mini spot welder (double sometimes) - and not just because of the sheer wholesale price they can access. Again you can't expect much reliability at these prices - It's very luck oriented. If you're lucky enough to get handed a farily matched batch of FETs on your board, you're probably not going to have issues once the mods are done and stay within parameters. If you're unlucky and get unmatched FETs for ex. 4 similar and one super low resistance (RDS) that one will take the whole load and give away first which is the typical failure mode of these welders. If you check my FAQs video I get more in depth about it.
@@Luca_Techy thanks Luca! I’ve watched quite a few of your videos. I had BifRC black pcb type welder which I’ve modified: separate power source just for running electronics (main welding pusle went from a different pack), soldered in copper bars to reinforce fet traces and made my own cables 6 GA and welding tips. I was using it with 5s 4500mah 40C zippy charged to storage voltage (19V) - i know a bit high but i was welding through 0.1mm pure copper + 0.15pure nickel sandwich! After 300welds the battery died (along with fets) - one cell tab burned off so i have converted it to 4s and kept continuing after fixing mosfets. Another 200welds went good on 4s (charged to max 16.8V this time, at 70ms time) but it happened again: burning fets and another inner lipo tab. I could not fix the battery anymore - nothing sticks to aluminium so couldn’t reconnect cells. So I bought a brand new 4s 10.000 mah 100C (200c burst) cnhl lipo and fixed the welder again with aliexpres mosfets from one batch, changed all at once. I was using it charged to storage (15.4V) at 30-40ms setting - it worked great even better than before BUT after 25welds it failed again destroying mosfets and burning inner lipo tab on a brand new battery :( I was thinking about going to get a genuine expensive mosfes from mouser to repair it again but gave up on that idea as i was too worried that it will happen again due to some unknown to me design flaws on that bifrc pcb v2 welder. Instead i have decided to go for arduino malectrics project and double the FET board and bought fets from kWeld (FDB0105N407L). I have managed to solder burned off lipo tab and made this pack into 3s 10.000mah. I have actually sent you an email yesterday and asked about some advice regarding the malectrics project as all the bits are on the way to me at the moment. I’d be thankful if you could have a quick look at it. Thanks mate for everything!
Can it weld 0.2mm strips?
It's stretching the limits and the risk of blowing a FET increases a lot, you need a very good battery but I personally would stick to max .15mm.
@@Luca_Techy thanks for a reply. By any chance is there a "cheap" spot welder for 0.2, that you know about?
@@GargamelCZ in all honesty I can't vouch for any as they all have limitations and design issues, it's also a matter of luck. Maybe you get one like this purple one (or even a wise maple or other red mini spot welder Bl/Bl models after doing modding) which have been built with a perfectly matched group of MOSFETS, then you're in luck and may overdrive them for .2mm. For 30 USD or Euros you can't expect to have a super product, when just buying 5 original matched Infineon or equivalent FETs will set you back over 60USD. If you really need to have that thickness then you might consider a more professional product in the range of 150Euros/USD like the one I recently reviewed. It's either that or take your chances! Just remember to apply rhe suggested mods!
@@Luca_Techy The thing is, that I need some non-standard battery cell layout and according to a table I found (with strip width/current) 0.15 wouldn't be enough. So I ordered 0.2 nickel strips.... Now I know, that $30 is realy cheap, but $150 on the other hand sounds expensive. I was hoping to find something around $75 mark.
Could getting this cheap board and replacing FETs work? I have a hot plate at my disposal and I can get access to a hot air solder, if needed.
@@Luca_Techy Oh my. It sure can weld 0.2 :-D
I've added 5 mosfets on the back side, some extra solder everywhere the current flows and even some thick copper wires next to mosfets... Then I connected it with short 10mm^2 cables to a fully charged 2000A car starter, set the welder to 99 and ZAP! It vaporized piece of 0.2mm nickel like it was nothing. :-O
Setup is pretty much done, I'd just like to know, if there's a spot on the board to which I can hotwire an external switch? I ordered the "YXKY" welder pen with springs and I'd like to take advantage of the built in switch it has. Is that something you can help me with? I don't mind if the board delay is still there even with the switch connected, contrary - if the delay is kept and the switch is added on top of that, it would be the best.
Excellent info but very hard to watch with the constant mouse/pointer movement.
Thanks, I'll try to move around less!
Salut j ai fait la modification comme sur ta video j ai fait 2 point les mosfet ont explosé ce circuit est vraiment trop fragile c est le 2 eme que j achete c est inutilisable ce truc😅 j achète un k weld c est une valeur sûre