So that one evening me and Samu decided to build a capacitive spot welder from scraps.

safety first (in case the caps blow up on fast discharge aka shorting).

A nice audio transformer

The resistors are to limit the current for charging.

Pulse duration and stuff was done on a Jockiboard and as high amp drivers we used some (maybe 3 in parallel) mosfets (hexfets) from old motherboards.

Some testing:

(thin metal)

(tea light aluminum cups)

We never got around to  finishing the spot welder … but who knows maybe someday.