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.
November 2016 - Already available from Mouser Electronics on Texas Instruments' new DS280BR820...
This circuit generates a pulsed tone whose frequency depends on C2 and whose flashing depends on...
The presented circuit is suggested by National Semicondictor in its 1994 Linear Applications...