Simplified power supply for electrodischarge machining at low frequencies

Modern electrodischarge-machining apparatus often employs paralleled transistors to switch the higher currents required in the process, while maintaining a fast pulse risetime. This method necessitates complex driving circuitry and the need for careful selection of devices. A simpler circuit, using fast-turnoff thyristors is described, which takes advantage of their high power gain and inherent high current-switching capability. The limitations of the circuitry are explained, and a method for increasing the higher switching-frequency limit of the circuitry is indicated.