DARK_ACTIVATED_ALARM_WITH_PULSED_TONE_OUTPUT

Published:2009/6/14 22:51:00 Author:May | From:SeekIC

NOR gates a and b form a low-frequency oscillator that is activated when the CDS cell，underdark conditions，causes NOR gate ato see alogic zero at one input This low-frequency (10 Hz) gates a high-frequency oscillator (c and d) to oscillate at around 1000 Hz．R1 can be varied to change the pulse rate and R2 to change the tone.R3 sets the trigger point.



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