Building a Spot Welder From a Transformer

Manekinen’s spot welder uses a limit switch connected to a moving electrode to trigger the weld current for up to 4 seconds (as set by a pot) while giving the user time to clamp on the electrodes. It produces 2.6V at 1kA.

One cool aspect of the project is that he repurposed the transformer from a Technics SU-V670 stereo amp, and rewound the secondary winding, allowing him to power the welder from wall current.

[Reposted from last year; H/T Michael Colombo.]