Automatic volume control for radio and TV systems - uses microphone to activate volume control matching environmental noise

摘要

The control system contains integrated preamplifiers and final amplifiers, and the volume is controlled by applied direct voltage. The volume control is set by this voltage. The supply line incorporates an activating unit, capable of changing the direct voltage. A microphone is used for regulating this activating unit in accordance with the environmental noise whose low value triggers reduction of the voltage strength, and vice versa. The inertia of the activating unit prevents short-term changes to be considered.