Photosensitive anti-theft alarm circuit diagram

Published:2011/5/17 3:36:00 Author:Ecco | Keyword: Photosensitive , anti-theft, alarm | From:SeekIC

Detector is PRY86 produced by Mullard PRY86, it only responses to wavelengths whcih is greater than 6μm, and it has no reaction on background light caused by continued exposure of sunlight. In order to gather infrared light onto the detector, the inexpensive mirrors replace lenses. μA776 is a programmable operational amplifier, and its bias current is only 300μA, which can be recharged by a small battery. Careful selection of Ra could make the the input voltage of the first operational amplifier be 2 ~ 6V. Only if when the theft walksin the area being monitoredandit will causethe changing of incident light, then this circuit will make the alarm relay RL pull in.



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