Abstract: A multi-purpose welding power supply to provide different modes of welding from a single unit. Two positive output terminals are provided, one for low amperage welding up to about 300 amp which includes an inductor and slope resistor and one for high amperage output up to about 600 amp which bypasses the inductor and slope resistor in the low amperage circuit. A pulsing circuit is provided to impose on the 300 amp output either 60 pps or 120 pps pulses on a standard direct current background. A variable pulse width control circuit is integrated with the pulsing circuit to vary the pulse width. A "hot start" feature is included with the 60 pps welding mode to provide 120 pps pulses for an initial pre-selected time period.