AM radio automatic search and trigger circuit

Shown is the AM radio automatic search and trigger circuit . This circuit is composed of an intermediate frequency amplification, a narrow-band filter and a detection circuit
. This broadcast holiday channel detection circuit is used in the automatic program search control circuit . The intermediate frequency signal
    of the AM radio circuit is divided into two channels for processing after intermediate frequency amplification (lFA): one channel extracts the intermediate frequency signal through the intermediate frequency transformer TF1, and the intermediate frequency signal is detected by the detector 1 and the audio signal is output and sent to the audio power amplifier circuit. At the same time, the intermediate frequency signal passes through the narrow-band filter to extract the carrier peak signal, and then passes through the detector 2 to detect the AM program signal, which is sent to the tuning control circuit as a trigger signal .