Abstract: A power supply system includes a plurality of dedicated power supplies, each of which has a separate output terminal for furnishing output current to just one respective load. Each dedicated power supply has a switch for turning the supply on and off independent of the remaining dedicated supplies. A single redundant power supply is also included which turns on when every dedicated supply is on. And, a control circuit is included which shares output current from the redundant supply, when it is on, with the loads of only a subset of the dedicated supplies, such that the total shared output current from the redundant supply and the respective output current from each dedicated supply in the subset are all substantially equal. This subset consists of any dedicated supply which fails, and those dedicated supplies whose output current to their load when the redundant supply is off exceeds the equalized current.

Abstract: A power supply circuit including A.C. input of either 110 volts or 220 volts coupled to a full diode bridge, across the output of which are provided series connected capacitors across which the desired system operating voltage appears. A voltage-controlled current generator for driving a diac and triac is connected between the input supply and the bridge capacitors. At 110 volt input, the current generator closes the triac and the circuitry operates as a voltage doubler to provide the desired system voltage. At 220 volt input, the triac remains open, and the full bridge and capacitors provide the same desired system voltage.

Abstract: A single-ended transformer drive circuit includes a transformer having a primary winding and a secondary winding and a switching transistor connected to the primary winding of the transformer and adapted to turn on and drive the transformer in the forward direction along its hysteresis curve, whereby an output voltage is generated in the secondary circuit of the transformer. An auxiliary transistor circuit is coupled to the transformer for driving it in the reverse direction along its hysteresis curve when the switching transistor turns off, whereby the transformer is reset and prepared for the next cycle of operation when the switching transistor turns on again.

Abstract: A circuit for controlling the base drive of switching transistor in a power supply wherein the switching transistor is coupled to the primary winding of a transformer linking the primary and secondary circuits of the power supply. Optimum operation of the switching transistor implies a desired level of saturation thereof. Base drive for the switching transistor is provided by a second conducting transistor. An excess of current flowing in the switching transistor is sensed, thereby effecting a reduction in the current flow in the second transistor. The latter condition causes a diminution in the base drive of the switching transistor and a return to its desired level of saturation.