AUDIBLE_LINE_MONITOR

Published:2009/7/14 22:31:00 Author:Jessie | From:SeekIC

Audio oscillator coupled to simple relay circuit gives alerting tone when power fails even momentarily. C2 determines duration of tone. With 2900 μF, tone lasts about 1 s, as warning that clocks will need resetting, Q2 is any PNP audio power transistor, K1 is 115-V SPDT relay, and PL1 is neon lamp.-J. R. Nelson, Some Ideas for Monitoring A.C. Power Lines, CQ, July 1973, p 56.



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