This circuit that we found in a 1990 documentation uses an LED as a sensor. The operational amplifier is equivalent to the 741 and the trigger adjustment is made in the potentiometer.
This transistor amplifier provides 35 W of power to an 8 ohms speaker and must be powered by a 59...
The input and output frequencies of this circuit depend on the coils and capacitors of the tuned...
The integrated circuit used in this configuration for noise reduction on FM radios is not common...