DEFLECTION AND POWER SUPPLY CIRCUIT WITH REDUCED START-UP DRIVE

摘要

RCA 74,394 In a remote controlled television receiver, the regulator circuit of the main television receiver power supply is made responsive to a remote on/off command signal in order to turn the receiver on and off. A deflection flyback transformer provides operating voltages to the ultor supply and other auxiliary supplies which power such load circuits as audio and vertical deflection. A horizontal output transistor is coupled to a B+ operating voltage terminal of the main power supply through a flyback transformer primary winding. After initiation of the on-state of the command signal, the regulator circuit rapidly develops a B+ operating voltage. The initially uncharged filter capacitors of the auxiliary supplies act as a low impedance shunt across the flyback transformer primary winding during the start-up interval. To limit the horizontal output transistor collector current and power dissipated during start-up, the horizontal driver stage holds the forward base current supplied to the horizontal output transistor each deflection cycle during start-up below the steady-state value.