WINDOW_FOIL_ALARM

Published:2009/6/30 2:03:00 Author:May | From:SeekIC

Combination of power-up mono MVBR and latch, using both sections of 556 timer, drives output line high when sensor circuit is opened at door or window switch or by breaking foil on glass. Once alarm is triggered, reclosing of sensor has no effect; S1 must be closed momentarily after restoring sensor circuit to tum alarm off. Circuit includes 22-s power-up delay that prevents triggering of alarm when it is first turned on.-W. G. Jung, IC Timer Cookbook, Howard W. Sams, Indianapolis, IN, 1977, p 231-232.



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