this post was submitted on 07 Apr 2026
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A bit delayed, but I also built my own with a starter solenoid and a used car audio capacitor. I use a bench power supply to change the capacitor and made a diy foot switch to trip the starter solenoid.
This approach is pretty cheap, very repeatable, and easy to control.
Changing the bench supply's voltage lets you dial in the amount of energy delivered per weld. Just keep in mind that energy stored = 1/2CV^2^ so don't jump from say 5 volts straight to 10 volts thinking that you're doubling the power - that's a 4x increase.
Wow I didn't know about car audio capacitors. What capacitance did you use? What voltage, typically? They are on the expensive side, but impressive. I bet they could also jump start car engines. I'm not keen on using a lead-acid battery so capacitors seem like an ok alternative.