Abstract: Welding arc stabilizing and igniting is effected with at least one pulse-forming condenser switched by spark gap or semiconductor switch to deliver a sharp discharge pulse through the winding of a pulse transformer, the magnetic energy thus built up in the transformer being then dissipated by a unidirectional diode bypass of the winding through the switch. The pulses are delivered by the transformer to the welding electrodes, and can be combined with pulses of lower voltage and longer duration by an appropriate series condenser-resistor combination in the transformer output. The pulse-forming condenser can be charged by simple resistor connection to the input of a step-down welding current transformer, or by transformer coupling to any source of AC welding current.