Direct radio radio circuit diagram

Photocoupler

The figure above shows a direct-release broadcast radio circuit composed of components such as variable capacitors. L, cl constitute a tuning loop, and cl is a variable capacitor. By changing the capacitance of CI, it is possible to select the station signal that it wants to receive.
C2 is a bypass capacitor that bypasses the high-value signal to ground and is isolated from the ground. Rl provides bias to pin 2 of the CIC7642. The role of the island is to filter out the high frequency signals remaining after the detection. C5 is a capacitor that improves sound quality. R2 is the load resistor of the CIC7642 and has automatic gain control. R3 is the biasing resistor of the triode VT1. For the load resistor of VT1, the bias current is also provided for rr2.