Published:2009/7/22 1:47:00 Author:Jessie | From:SeekIC
Simple circuit using LM380 audio amplifier IC gives excellent performance. First transistor amplifies random noise which is greater in frequency than normal spectrum of voice during no-signal conditions. CR1 and CR2 rectify noise. Second transistor conducts and clamps U1 off when there is no signal. Increasing value of C1 increases gain of noise amplifier, but small value of C1 makes circuit less susceptible to heavy noise peaks.-R. Harris Another Squelch Circuit, Ham Radio, Oct 1976,p78.
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