Abstract: A solid-state ballast circuit for starting and regulating a gaseous discharge lamp which is operated on direct current is arranged so as to permit the use of low voltage switching relays to effect polarity reversal of the lamp under load. A high voltage pulse source is connected in series with the lamp and a low voltage switching relay is connected in a manner to effect polarity reversal of the DC voltage applied to the combination of the high voltage source and lamp. The voltage appearing across the high voltage source is prevented from reaching the switching relays by virtue of a bridge rectifier circuit connected such that the pulse source and lamp appear as a current source for the rectifiers. The output terminals of the bridge rectifier arrangement are connected between the output terminals of the low voltage DC source thus limiting the voltage applied to the switching relays to a value not exceeding that of the DC source.

Abstract: A circuit including a switching regulator and a pair of pulse transformers for selectively starting and operating a pair of arc discharge lamps. The lamps are arranged to be connected in parallel across the regulator output, and in order to operate one lamp at a time, the circuit is provided with low-voltage switching means for selecting the lamp to be started and operated. This switching means, in the form of a ganged switch, includes a switch portion for completing an enable circuit from the regulator controller for enabling the regulator and a pulse generator, and a second switch portion for steering pulses from the generator to the pulse transformer associated with the lamp selected for operation.

Abstract: A feedback control system for use in an electrostatographic apparatus capable of, by successive approximation, approaching a value of charge on an electrostatographic imaging surface which is in correct proportion to a reference voltage thereby to result in near zero circuit error. A predictor circuit samples, during a sample period, the reference voltage, the charge on the imaging surface and the output of a first, conventional feedback loop to produce a corrected reference voltage value for the loop. During the sample period, this corrected reference is stored in first memory while a second memory receives a constant input reference for feeding to the loop. At sample end, the constant input reference is disconnected from the second memory and the contents of the first memory are fed to the second memory thereby providing the corrected reference voltage to the loop.