SWITCHING CIRCUIT UTILIZING THE BASE STORAGE CHARACTERISTIC OF A TRANSISTOR FOR USE IN A FACSIMILE SCEIVER AND THE LIKE

摘要

A document/copy carrying drum of a facsimile transceiver is rotatably driven by a synchronous motor. The synchronous motor is connected as a load in series with a first transistor and a first power supply of one polarity. The synchronous motor is also connected in series with a second circuit and a second power supply of opposite polarity so as to apply DC voltages of opposite polarity during alternate conduction of the transistors. Conduction of the transistors is controlled by alternately applying a series of relatively low voltage pulses to the bases of the transistors through high frequency isolation transformers. The pulses are separated by a time interval less than the base storage time of the transistors so as to assure continuous conduction between the collector and emitter of a transistor while a series of pulses is applied to the base thereof.!