AUDIBLE_ALARM_FOR_TIMER

Published:2009/7/13 4:28:00 Author:May | From:SeekIC

Used with 2-min timer for developing photographic paper, to produce short waming bleep indicating end of developing time. Input D is taken from output of Schmitt trigger that changes state when 2-min ramp generator times out. Tr9 and C4 to-gether lengthen short reset pulse so MVBR Tr10-Tr11 oscillates long enough for signal to be heard.-R. G. Wicker, Photographic Development Timer, Wireless World, April 1974,. p 87-90.



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