Abstract: An automatic gain control circuit has its a-c signal input terminal connected directly to the numerator input of an analog divider, and connected through a peak detector to the denominator input of the analog divider. The quotient terminal of the analog divider provides a gain-controlled a-c signal output. The AGC circuit produces a constant amplitude output signal so long as the amplitude of the input signal exceeds an adjustable reference voltage applied to the peak detector. The reference voltage may be changed to change the range of input voltages resulting in a constant-amplitude output. The AGC circuit responds almost instantly to control a sudden increase in input voltage.