motor starter relay
My old Airco tig has a hand crank amp controll and HI freq switch. It would want to keep welding after I turned of the HF switch. I never changed it but I have a couple of Motor starters like used on commercial equipment, They are made work on 3 phase but you just hook up the 2 wires for single phase, they have the actuating coil that can be interchanged for different controll voltages, I was going to use a 110 v coil and a $ 20 foot pedal from graingers. But I bought a Newer Lincoln Sq wave 255 Tig. I still like the old Airco to stick weld with since I can use HF stick when welding on painted dirty farm equipment. The Lincoln HF only works on Tig. you would use the foot pedal on the weld power supply circuit.