Automatic Volume Control. A circuit which adjusts the gain of an audio device in inverse proportion to the incoming signal level. An example is a portable tape recorder which is designed for speech recording; when the speaker is close to the microphone, the gain is reduced so as not to overload the tape. Also, a circuit which increases a TV or radio receiver’s gain when it is tuned to weak stations and decreases the gain when it is tuned to strong stations. Called AGC (Automatic Gain Control) in TV.