Power source for capacitor discharge welding of studs of 3 to 8 mm diameter and other accessories, with tip strike. It is suitable for applications in heating systems, installation and maintenance works. It enables welding of studs on non-treated or non oxidized surfaces in steel, stainless steel, galvanized steel, brass and, in particular, aluminium. The welding process is so short that it causes no alteration to the opposing surface even if painted, plastic-coated or galvanized. 115-230V automatic voltage reversal. Complete with gun, earth cable with clamp and accessories.