The infrared detection alarm circuit

Published:2011/7/7 0:21:00 Author:qqtang | Keyword: infrared detection alarm | From:SeekIC

Working principles The circuit principle is in figure 1, which consists of the infrared sensor, signal amplifier circuit, voltage comparator, time delay circuit and stereo alarm circuit, etc. When the sensor IC1 detects the infrared signal emitted from the human body, the 2-pin of IC1 is outputting a weak electric signal which is firstly amplified by the first-stage amplifier circuit composed of VT1 and so on, and then it is sent to the computing amplifier IC2 by C2 for gain expansion and low-noise amplification, at the moment, the signal output by 1-pin of IC2 is strong enough.



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