TV CRT line scan oscillation maintenance system - uses controlled switching of line output transformer windings and DC supply to power all TV circuits

摘要

Sawtooth oscillations are maintained in a horizontal deflection circuit including a deflection coil and a bidirectional transistor switch, controllable by a first winding of the line output transformer. A second winding, closely coupled to the first, is connected to a DC voltage source by an identical transistor switch. The first winding is effectively utilised for line scan only when a third controlled switch, using a diode with relatively short recovery time, is closed. The momentary short-circuit during a forward scan period does not react upon the DC source. Alternatively, the third controlled switch may be only a diode with relatively long recovery time and no parallel transistor. Sound reproduction stages and other circuits of a TV receiver can be supplied with power from the line output transformer. The first winding is disconnected whilst the second winding is connected to the power supply connectors of the end of the recovery time.