After some overdue procrastination, I finally finished my build. At first, the welder wouldn't send the pulses. It was because I used a Barrel jack>RCA adapter for connecting the foot switch, but the adapter didn't work
Initially, I bought that adapter to save me some work, but in the end, had to cut the foot pedal cable to solder a RCA connector anyway. That taught me a lesson for cutting corners ... Hooked the device to my Marathon 85 Ah solar batteries (yeah, I know they're not meant for that) and a homemade 12V LiPo Pack. First tests on a piece of nickel strip: it didn't survive the surge whatever the settings. After pushing the nickel strip firmly onto the cells, and reducing the settings to the minimum (something like P1=0.1 P2=0.2 D=5), the welds happen, and the result is pretty ! Very very satisfied, I now have all the tools to get my project going !!
The power-on LED doesn't light up, probably because it's a blue one, and needs a higher voltage. Will fix that if I find the time.
All in all, thank you pguk
, for selling this spot welder (and power board) on ebay cause it prevented me from buying the chinese MOT welders that have very bad reputation
I would never have thought there would be such a project on endless-sphere ! So useful ! And takes little space