Pulsed power supply

A reversible control circuit for applying voltage pulses of opposite polarities to a load whereby the average current flowing in the load is a function of the maximum voltage at which the voltage pulses are applied and the duty cycle of the control circuit. The circuit may be utilized to control an electric motor field wherein the motor shunt field winding is connected across a four switch bridge circuit supplied from a direct current or rectified alternating current power source. Current flow in the field winding through a first pair of switches on opposite sides of the bridge can be reversed by opening the first pair of switches and closing the second pair of switches. If the switch pairs are alternately closed and opened in a rapid cyclic manner, the direction and magnitude of the current flow in the field winding can be controlled by varying the duty cycles of the switch pairs.