About 30 years ago I picked up a Tab book with dozens of home projects, many based around a type of relay which I'd never seen over here at the time, nor anywhere since.
It was basically a relay which incorporated transformer action to provide a low-voltage switching line. The primary winding is fed directly with a constant 120V supply, and the secondary winding forms the control circuit, so when you short the secondary it increases the magnetic field enough to close the contacts.
Does anyone still make these?
