Abstract: An interlock switch (14) is provided between a housekeeping power supply (12) and a pulse width modulator (16). The pulse width modulator (16) pulses a field effect transistor (18) to generate alternating current (AC) to be passed by a transformer (26). The AC is converted to direct current (DC) by a converter 34 to provide an output voltage. If the switch (14) is opened, power to the modulator (16) and transistor (26) is terminated. No AC power is transmitted. Thus, since the transformer (26) only transfers AC, no voltage is generated at the output of the system.

Abstract: The present invention is an apparatus for controlling the ignition of an internal combustion engine. The present invention employs a high voltage transistor, preferably a high voltage MOSFET, to switch DC voltages on the order of 1 kV to regulate the flow of current to an input tap of a primary ignition transformer or coil. The high voltage transistor is controllable by conventional logic-level voltages produced by an ignition control module.

Abstract: A flash exposure photocopier provides a mechanism for automatically controlling photoreceptor exposure levels to compensate for the effects of documents having backgrounds of different densities. A photosensor and lens assembly is located within a flash housing in a position whereby a large portion of the document is imaged by the lens onto the surface of a chip having a plurality of individual photosensors contained thereon. The outputs of each photosensor are integrated and applied to a comparator set at a particular reference level. The comparator output controls the duration of the flash source so as to quench lamp operation when an input level is reached corresponding to the particular reference level set. The integrated photosensor outputs are also summed and a signal representing their average value is compared to the signal which triggers the comparator. The ratio of these signals is used to identify documents with high area coverage and hence high toner usage.