Patent ID: 7060935

Claim:
A power supply connectable to an AC line voltage source for AC electric arc welding by an AC arc current across a gap between an electrode and a workpiece, said power supply comprising a device for converting an AC output voltage to a DC voltage between a positive terminal and a common terminal at substantially zero volts and a negative terminal and said common terminal, a first switch for connecting said positive terminal to said common terminal across said gap when a gate signal is applied to said first switch, a second switch for connecting said negative terminal to said common terminal across said gap when a gate signal is applied to said second switch, generating means for generating a gate signal of pulses at a given frequency, a first logic gate for directing said gate signal to said first switch for a first time, a second logic gate for directing said gate signal to said second switch for a second time, operating means for alternately operating said logic gates to create said AC arc current, and a free wheeling diode circuit selectively operable at said gap in coordination with said first or second switch.