Direct broadcast radio circuit

Shown is a direct broadcast radio circuit composed of variable capacitors and other components . L and cl form a tuning loop. cl is a
variable capacitor. By changing the capacitance of CI, you can select the radio signal you want to receive.
    C2 is a bypass capacitor, which is used to bypass the high signal to the ground and isolate it from the ground line. Rl provides bias voltage to pin ② of CIC7642.
The function of the island is to filter out the high-frequency signals remaining after detection. C5 is a capacitor that improves sound quality. R2 is the load resistor of CIC7642 and has automatic
gain control function. R3 is the bias current resistor of transistor VT1. Any load resistor of VT1 also provides bias current for rr2.