Nuarc Company, Inc.

Ralph G Foose

John D Crabtree

A bank of high power quartz iodine lamps is regulated so that changes in light output from the lamps for a 40 volt change in AC line voltage is reduced from 132% to 10%. To accomplish this, a regulating pulse width modulator is synchronized to the AC line so that pulse width modulated pulses are developed the trailing edge of which is coincident with the zero crossover points of the AC line voltage. The variable leading edge of these width modulated pulses is employed to control the firing point of semiconductor switching devices in series with the lamps, the average voltage across the lamps being sensed and employed by the regulating pulse width modulator to vary the width of the pulses in the correct direction to maintain the lamp voltage constant despite large changes in line voltage.

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Aurora, OH, United States of America

Ralph G Foose