Abstract: A versatile electrical circuit for controlling the operation of a variety of high intensity discharge, high and low pressure sodium, mercury vapor, metal halide, or xenon arc lamps uses a pulse-width-modulator to regulate the alternating or direct current drawn through the lamp from a regulated power source in accordance with the lamp power rating and the desired light intensity setting and in response to the current sensed through the lamp, and may be powered by an AC or DC power source. The circuit uses a H-bridge to apply an alternating voltage to the lamp that does not include any transformer.

Abstract: A pulse-width ac voltage regulator that provides a precisely ac output voltage without the need for any inefficient protective circuitry for ensuring proper operation when it repeatedly switches between its two alternative operating modes. A transformer is arranged with a first winding connected between an input terminal and an output terminal and a second winding connected between one end of the first winding and a control terminal. A special switch assembly including four separate circuits, each having a series connected transistor and diode, is controllably switched such that the second winding is alternatively shorted or excited, to provide a stepped-up (or stepped-down) voltage out of the first winding. The transistors are controllably switched at a frequency substantially greater than that of the ac input signal and at a duty cycle selected to provide the desired ac output voltage.

Abstract: A switching AC voltage regulator including a transformer, two solid state AC switches, and sensing means controlling the switches to produce the desired output voltage. The two switches conduct alternately and are switched at a rate much higher than the frequency of the regulated AC voltage. When the first switch is activated, the transformer is shorted out, causing the output of the transformer to equal the input. When the second switch is activated, normal transformer action occurs, creating an output voltage either higher or lower than the input, depending on the transformer arrangement. The duty cycle of the switches is varied to provide precise control of the output voltage.

Abstract: A non-dissipative snubber circuit for use in a power bridge circuit having a pair of switching power transistors for controllably coupling pulses of electrical current in opposite directions through the primary winding of a power transformer, to generate a 60 hertz ac power signal. The snubber circuit includes a separate snubber capacitor shunting each transistor, with the current flowing through the transformer's primary winding being diverted to charge one of the snubber capacitors each time the associated transistor is switched off. When the transistor is again switched on, the capacitor is reinitialized by discharging it through an inductor.