AGC circuit with 60 hertz hum compensation

Year	Description
1992	Invention patented by Yoshikazu Toyoda, Takashi Hashimoto, Tokuji Iijima, and Satoshi Iwasaki on April 8th, 1992. Abstract: An AGC circuit comprises an AGC filter, a hum detection circuit, and a time constant control circuit. The hum detection circuit detects a hum component included in an AGC signal. The time constant control circuit automatically controls the time constant of the AGC filter in accordance with the level of a detected hum component in such a manner that when the level of the hum component is large, the time constant of the AGC filter is varied to be small, while when the level of the hum component is small, the time constant of the AGC filter is varied to be large. Thus, the AGC filter outputs an AGC signal from which a noise component, particularly a hum component, is eliminated on the basis of a time constant determined by the time constant control circuit, so an AGC is carried out without the influence of the noise component included in the AGC signal.
Source: selected by the editor from original sources.

Invention: AGC circuit with 60 hertz hum compensation