This Scanner Voice Squelch Circuit Diagram detects the presence of audio (voice) on the output of a scanner. If the scanner stops on a `dead carrier` or noise, the circuit mutes the speaker to avoid annoying noise.
Ul amplifies speech and drives rectifier D1/D2 and switch Ql.
Comparator U3 drives speaker switch Ql and indicator LED1. Q2 completes
the speaker path to ground. U2 is an audio amplifier to drive the
speaker. R3 is a volume control. PL1 connects to the scanner speaker or
to the headphone jack .
Build a Scanner Voice Squelch Circuit Diagram
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