Signal level indicator driving circuit

Claim 1

A tuning indicator driving circuit for use in a radio receiver circuit including an automatic gain control circuit, comprising: detector means for detecting a dc component of an output of the automatic gain control circuit, said detector means including a signal amplifying element in the receiver circuit generating an output signal containing said dc component and an ac component, said dc component being controlled by the output of the automatic gain control circuit, means for shunting said ac component of said amplifying element output to ground, and a dc current path means connected to said amplifying element output for transmitting the dc component of said output, said dc current path means comprising means for determining a threshold voltage above which a current is allowed to flow therethrough, said voltage determining means including means for shifting the level of said dc component in said current path means and an element having a threshold voltage connected to said level shifting means; and a tuning indicator means driven by the output of said threshold voltage determining means.