AUTOMATIC TURN-OFF APPARATUS FOR A RADIO OR TELEVISION RECEIVER

摘要

-19- RCA 73,456 A television receiver includes a tuning system comprising a phase locked loop (PLL) configuration and an automatic fine tuning (AFT) configuration which are selectively enabled to operate in response to respective levels of a MODE signal to tune standard and nonstandard frequency RF carriers. In the absence of an RF carrier for a selected channel, the operations of PLL and AFT configurations are alternately enabled and the level of the MODE signal changes accordingly. The MODE signal is applied to a capacitor which develops a control voltage for turning the receiver "off" after the MODE signal has changed levels for a predetermined time because of the absence of a RF carrier.