Abstract: This percussion welding power supply supplies welding energy through an arc between two work pieces that are forced together during or immediately following arcing. The power supply comprises a welding transformer having a primary winding and a secondary winding. Across the secondary winding, welding electrodes are connected for supplying welding current between the secondary winding and the pair of work pieces to be welded together. The power supply further comprises a capacitor bank having a pair of output terminals and means comprising electronic switching means in series with the primary winding and the output terminals for selectively connecting the output terminals across the primary winding. Control means is provided for rendering the switching means conductive, thereby causing the capacitor bank to discharge through the switching means and the primary winding to effect a welding operation.