The wave on the scope is heavily overloaded. The audio input is where the signal generator is output is blue line top of 47k resistor.
Close the switch bottom right to activate the limiter and watch the wave become undistorted, vary the input amplitude to see the affect on the output. This is a simple and basic circuit but it's effectiveness is clear to see. 80mv input for 1v output. Max input is about 550mv limiter off, and over 12v limiter on. It has fast attack and response with no hunting.
