When I saw the AGC circuit by Peter Parker VK3YE, I realised it solved a problem common to many simple homebrew receivers. You cannot automatically control the gain of a receiver with fixed gain stages. Most simple receivers do not have IF stages, let alone variable gain IFs. And the LM386 has no gain control. So it’s easy enough to sample the audio at the volume potentiometer, amplify it, rectify it for a source of AGC. But then you need a voltage controlled gain stage ( a Voltage Controlled Amplifier or VCA). If your receiver doesn’t have one, AGC won’t work, and you with have to either add a VCA in the receiver somewhere or replace one of the fixed gain stages with a VCA. Until now.