Tape player adapter for car radio

摘要

A portable stereo cassette tape player is connected to an FM automobile radio through an adapter having an input plug which is inserted into the audio signal output terminal of the tape player and an output plug which is inserted into the cigarette lighter receptacle of the car. The direct voltage from the car battery is filtered and connected to a frequency modulation oscillator stage in which the audio signal from the tape player frequency modulates the oscillator. The weak frequency modulated signal is coupled into the FM car radio through the cigarette lighter receptacle by stray capacitance of the wires connected to the common power source or battery and proximity to the antenna and input stage of the radio. A tuning capacitor tunes the oscillator frequency to an unused location on the dial between local FM radio stations so that the audio signal can be heard on the normal frequency modulation radio band over the radio loud speakers.