Abstract: In an electric arc welder including a main transformer with a primary stage coupled to a secondary stage in which is created an AC output current, a first switch opened and closed at a given rate to pass a series of first pulses of DC current in a first circuit having a first lead and through at least a portion of the primary stage in a first electrical direction, with each of the first pulses having a length determined by the time the first switch is closed, a second switch opened and closed at the given rate to pass a series of second pulses of DC current in a second circuit having a second lead through at a least a portion of the primary stage in a second electrical direction with each of the second pulses having a length determined by the time the second switch is closed, and a control circuit for rapidly closing the first and second switches in sequence to induce an AC current in the output stage, the improvement comprising: a first current transformer surrounding the first lead of the first circuit to d

Abstract: A dual stage power supply for creating a D.C. welding current through an arc welding gap, the power supply comprising an input inverter stage with a full wave rectified A.C. voltage source and an output capacitor; and, an output chopper stage connected across the output capacitor, with the chopper including output leads connected across the arc welding gap, a switch for gating the output current of the inverter stage at a controlled rate through the leads and through the arc welding gap, an output inductor in one of the leads between the switch and the arc welding gap and a free wheeling diode across the leads between the switch and the output inductor.