This audio amplifier circuit was found in Radio Electronics magazine from June 1966. The circuit is a commercial RCA type and is powered by mains power.
The recommended distance between the emitter and the phototransistor is 10 mm for this...
The input and output frequencies of this circuit depend on the coils and capacitors of the tuned...
This circuit was obtained in a 1991 publication. What it does is to amplify a signal with unit...