Car radio amplifier including microphone - uses microphone signal to make gain dependent on noise inside car

摘要

The car radio amplifier has its gain controlled by the noise level in the car. A microphone i installed inside the car to the noise level inside the car and its proportional output signal is amplified and rectified and passed to an adder. The output of the adder is used to regulate the gain of the audio amplifier of the radio. The adder adds in a voltage that ensures that the audio amplifier has a minimum gain. Audibly is maintained even at high noise levels in the car.