PTT_LATCH

Published:2009/7/14 3:29:00 Author:May | From:SeekIC

Eliminates need for holding down microphone switch continuously while transmitting. U1 is inverting hex buffer, and U2 is dual CM0S D flip-flop. When S1 is depressed, input to U1A goes low and its output goes high, making U2A and U1B together turn on Q2 and energize relay K1. Q3-Q5 serve as optional silent power switch for use when relay noise is objectionable.-B. Lambing, DC Latch Circuit, Ham Radio, Aug. 1975, p 42-44.



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