Automatic gain control for a headset

摘要

An improved automatic gain control circuit for a telephonic headset having a variable gain stage in the audio signal path, the gain of which is controlled by a control signal appearing across a capacitor. A peak detector is used to detect the presence of peak signals above a predetermined minimum threshold level and a substantially conventional automatic control network is formed around the capacitor in response thereto. During the absence of such peak signals the capacitor is disconnected from the AGC control network and holds the control signal at a constant level. Passage of a predetermined period of time in which no peak signals above the threshold are detected causes a switch to connect a nominal gain setting network to the capacitor to establish a quiescent no signal gain for the circuit which is lower than the maximum gain which the AGC can achieve when it is active.