| 摘要 |
Parallel connections are provided from high voltage power supplies of opposite polarities through separate light dependent resistors to an electrical load. Separate light emitting diodes are associated with each of the light dependent resistors and are driven by a differential amplifier having one reference input and another input responsive to load current or voltage. The load current or voltage is regulated or programmed through a relatively low voltage power supply and a programmed or regulated amplifier which manipulates the illuminating effect of the light emitting diodes to vary the resistance of the light dependent resistors in a prescribed manner. This manipulation of the resistances imposed in the parallel power leads produces an alternating current across the load. The reference input to the differential amplifier is preferably adjustable. Operation of the device is particularly useful in imposing a desired alternating current frequency on the high voltage, low current power supply to corotrons in a xerographic reproduction device.
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