Thinking what could be done this weekend i knew immediately when i seen some caps derived from junk yard diving some time ago. A small spot welder.
I was thinking before about building one and consider two strategies. First one was to build a line powered H-bridge power supply powering a few KW switching transformer and generating alot of amps on the other side (something similar like a small induction heater i designed) in short bursts. Since i wanted something more safe and transportable i decided for capacitor discharge system.
Checking what other fellows have done in this area i understood second method is better and widely used. The only change is that other people use PIC-s, ATmega and what not to drive the power bridge. Since im old school analog and any kind of programmable device is banned from my lab i will design an analog version of it
I did the power side today, tested and working powered by a FG and mosfet drive IC. Tomorrow i will build the control electronics. Basically what im aiming is 2 X 555 for simple PWM and second will be used as "one shot" switch and as an time adjustable interlock between "welds"