Abstract: A high voltage power supply is regulated using a light dependent resistor. A feedback circuit from the load controls the input to a light emitting diode which is optically coupled to a light dependent resistor connected in series with the load. Increases in the load current tend to reduce illumination on the light dependent resistor, thereby increasing the resistance of that circuit element which reduces the load current. The converse is also true. Regulation may be applied to a D.C. power source or to an A.C. power source by developing a signal indicative of average current level and applying it to the light emitting diode to control the light dependent resistor. The high voltage power control of the invention is particularly useful in regulating corotron voltage levels in a xerographic reproduction device.

Abstract: 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.

Abstract: An apparatus for substantially eliminating the effects of a nonsinusoidal current from a reactive or nonlinear load as applied to a resistive load requiring an input current that appears to be sinusoidal. If the amplitude of the current source as applied to the resistive load can be controlled through a switching regulator by matching a sine wave reference signal with current inputed from the current source then said input current may be forced into a sinusoidal mode that is in phase with the voltage thereof. Accordingly, with the input current in a phased sinusoidal condition, harmonic elimination and power factor correction may be afforded to the inputed power relative to the resistive load.

Abstract: A power supply circuit for generating true sine wave signals by regulating the average value of the signal, whereby the RMS value of the signal is regulated accordingly. By monitoring the circuit through the load, represented by a monitored voltage value, a feedback network is coupled to a variable resistor in conjunction with other circuitry to maintain a constant voltage ratio to the power transformer assuring a properly shaped wave at a larger or smaller variation.

Abstract: A circuit for concurrently producing regulated high voltage a.c. current and bias d.c. current on one output line, where all regulation is accomplished in low voltge circuits, power supply being particularly useful as the power source for copier and duplicator corotrons. The basic wave shape is a rectangular wave which is amplified and regulated for application as the a.c. input to a corotron. The corotron itself is used as the rectifier for the d.c. bias current, with this current being variable in either the positive or negative direction by varying the symmetry of the a.c. rectangular wave. Since the part of the wave which has the shorter duration must have the higher amplitude, and current in the corotron increases with voltage, a feedback loop which controls the rectangular wave duty cycle will regulate the d.c. bias current as well.