Infrared alarm switch circuit diagram

Published:2011/9/26 22:15:00 Author:Rebekka | Keyword: Infrared alarm switch | From:SeekIC

The figure shows the infrared alarm switch circuit. It uses the most popular domestic and international human pyroelectric PIR sensor as the signal detector. It has a high sensitivity, the detection range is up to 10m or more, the depression angles is up to 86 degrees, horizontal viewing angle is up to 120o. It is only sensitive to the specific wavelength infrared light that released by human body, so it has a minimal malfunction. When someone walks in the detection region in 0.3Hz ~ 3Hz frequency. It can give birth to weak signal sense. It is amplified by the UA, UB two-stage and outputs strong signal of 0.5V ~ 5.5V from the U-B7 feet. VD1, VD2, R10 ~ R13 and UC form the threshold comparator. The signal voltage induced by PIR can be positive or negative, so the U-B7 pin outputs voltage can be positive or negative (in terms of center voltage 3V). When the voltage on C8 is less than 13 feet (1V), the pin 14 has no output. Thyristor turns off, the lights automatically turn off. People sleep at night or when there is no one at home, you can turn off the switch S. If there is a thief sneaked into the detection region, the lights will be accompanied by ringing. It can scare away the thief, played the role of security.



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