I'd like to BUILD A CAPACITIVE DISCHARGE SPOT WELDER

[eltonjohn]

capacitive discharge spot welder

Before i get into this project i like to gather as much information as possible
i need to weld aluminum foil .2mm thick so i'm thinking that a current of 1000A
will do. For that i decided that .5 FARAD to .7 FARAD is enough . FIRST that i need to know where to get CHEAP high microfarads capacitor..(50KuF)
and also once the CAP BANK is charged how i SWITCH it to the ELECTRODES
a RELAY may not be very GOOD too much loss ..
what type of SOLID STATE RELAY shoul i use (again cheap)

 

[jochez]

how to build a spot welder

For aluminium welding you nead about 40A/mm.
Solid state device should be a tyristor I think.

 

[eltonjohn]

hobby spot welder

I FOUND a N CHANNEL MOSFET not very EXPENSIVE and allows small PULSES of up to 1000 AMPS!!! ..the only problem is that i will need to do a POSTIVE GROUND MACHINE ...but is OK ..if a ISOLATE all ...