Flip the dash switch, your Bluetooth audio device connects automatically to your old car FM radio.

FM Receiver Circuit Schematic The coil details are presented in the fm receiver circuit diagram. The radio receiver is adjusted on different stations with the help of C5. P1 potentiometer is adjusted ...

How's it work? You can easily turn your phone into an FM radio if it has an embedded chipset and the proper circuitry to connect that chip to an FM antenna.