This squelch circuit is placed at the input of the single receiver audio amplifier stage. Its purpose is to silence background noise. The circuit is from an 80's documentation.
Found in a 1990s Electronics Now, this circuit uses a period-specific integrated circuit that...
This circuit serves to isolate analog signals, for example, audio signals in a secure link...
Found in Popular Electronics from the 90s, this circuit has 7,500 ohm of input impedance. The circuit...