M_ESSAGE_CONTROLLED_RECORDER

Published:2009/7/14 5:36:00 Author:May | From:SeekIC

Circuit turns on tape recorder whenever input signal is present in receiver, and turns off recorder when signal goes off. Applications include monitoring local FM repeater for daily usage to obtain call signs of users, or unattended recording of messages left by other amateur stations, Uses cheap cassette tape recorder with autostop, operating at 6 V obtained from 12-V receiver sup-ply by series regulator Q1 and zener D1. Connection to mute or squelch circuit of receiver is shown for set having CA3089E in IF tail end. Darlington pair Q2-Q3 effectively removes base supply for on to turn recorder off. LED comes on when recorder is on. Q1 is NPN power transistor, while Q2 and Q3 are small-signal NPN transistors.-F. Johnson, Automatic Taping Unit, 73 Magazine, May 1977, p 98-99.



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