PRECISION_LIGHT_ALARM_WITH_HYSTERESIS

Published:2009/6/14 22:57:00 Author:May | From:SeekIC

The TL081 is used as a comparator in a Wheatstone bridge circuit. When the CDS cell resistance decreases due to exposure to light, the output from IC2 cause the low-frequency osciLator(a) and(b) to generate a 10-Hz square wave, gating the 1000 Hz oscillator(c) and(d) on and off. This signal dri-ves an amplifier. R3 controls hysteresis, which reduces on-off triggering near the threshold set by R4.



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