This is another smaller project I undertook one time when I came across a discarded microwave oven
at the dump (yes, I’m a champion dumpster-diver). The project turned out to be a bit more involved
than I had expected.... It consists of a microwave oven transformer (MOT), a few switches, and some
4 AWG wire.
I removed the secondary winding from the MOT (which was no small feat) and bent six feet or so of 4
AWG wire into three new secondary turns. I added a light switch in series with the primary winding
for a bit of safety, and then put everything into a simple wooden housing. Each end of the thick
wire was soldered to a flattened copper pipe; one of those in turn was bolted to the wooden housing,
and the other through a pivoting arm. The bolts are long enough to touch when the arm is downward,
and work as makeshift contacts. Although it works for thin pieces of metal, I believe the steel
contacts/bolts are not as effective as copper would be. I measured the voltage across the secondary
winding to be about 2 volts. However the current maxed out the inductive ammeter, pushing the needle
well past the 300 amp mark. I estimate the current to be just over 400 amps.