Abstract: A drive circuit for a power switching transistor, in which an actuating circuit provides a low level gating current to actuate and maintain the transistor in a conductive state, and a bootstrap drive circuit is provided to enable operation over the full load range of the transistor with minimal input power loss. Rapid turn-off is facilitated by means of a deactuating transistor which connects the base of the switching transistor to a negative pull-down voltage level, and which also diverts gating current away from the switching transistor. A shunt circuit is provided in association with the bootstrap circuit to prevent saturation of relatively high gain switching transistors.

Abstract: The circuit utilizes a tertiary transformer for coupling a driving current to an inductive load. A switching transistor in series with the primary winding of the tertiary transformer initiates current flow thru the primary winding, which current, in turn, induces a current in the secondary winding of the tertiary transformer. The inductive load is connected across the secondary winding. The tertiary winding of the transformer is serially connected by a back-biased diode between the driving power source and a reference potential so as to quickly dissipate the energy stored in the secondary winding and the inductive load back to the driving power source when current in the primary winding ceases.

Abstract: In order to achieve the capability to operate a plurality of identical power supplies in parallel, whereby the drawbacks of the conventional master-slave regulator relationship are avoided, the regulator of each power supply is provided with a load current sensor and a secondary differential amplifier circuit responsive to a predetermined load current for controlling the normal reference voltage supplied to the primary, voltage regulating differential amplifier. As a result of the inevitable, within-tolerance differences in the characteristics of two paralleled regulators, one supply will assume constant current operation at the predetermined load current while the other supply will operate at constant voltage and will carry the remainder of the actual load current. As many identical power supplies as necessary for a given application may be operated in parallel, and a single one will automatically operate in the constant voltage mode while the rest operate in the constant current mode.