A generator of high current pulses.

摘要

A circuit for pulsing the output of a dc power supply (2) connected across a load such as a welding arc. The circuit has a first SCR (12) connected in parallel with a resistor (14). The SCR (12) controls the pulse current and the resistor (14) controls the background current. Each pulse is terminated by the action of a second SCR (18) and a capacitor (16) connected across the first SCR (12) by applying a control pulse to the gate of a second SCR (18). The capacitor (16) is charged by a power supply (20) and is connected by the second SCR (18) so that the first SCR (12) is reverse biased and hence is turned off to terminate the pulse. Immediately the first SCR (12) turns off, the capacitor (16) is charged in the opposite sense to the charge derived from the power supply (20) and this in turn causes the second SCR (18) to be reversed biased by conduction through the resistor (14) and turned off a short time after the first SCR (12) is turned off. The circuit permits control of individual pulses and pulse trains in accordance with variations in any of a range of external control variables.