FM radio automatic search and trigger circuit

Shown is an FM radio automatic search and
trigger circuit . This circuit is mainly composed of operational amplifier
yPC1167C, detector and amplifier, etc. It is used for
automatic program search circuit and broadcast station signal detection circuit.
    To perform automatic program search,
when searching and tuning to a program channel, an identification signal is formed and the control circuit is notified to stop tuning
.
    yPC1167C is a frequency identification circuit (the aforementioned circuit) in an FM radio . (The snow pin is the audio signal output terminal, and the ◎ pin is the level indication signal output terminal. These two signals are rectified respectively to drive the transistor Ql. . When the level of the output signal of either of these two signals reaches a certain value after being rectified by the rectifier diode, the transistor Ql is turned on, and the collector outputs a jumping pulse signal.