The alarm circuit diagram using DS-505 pyroelectric sensor

Published:2012/10/25 21:26:00 Author:Ecco | Keyword: alarm , pyroelectric sensor | From:SeekIC

In the circuit, DS-505 receives the infrared radiation from human body and turned it into a voltage signal, then it is amplified by VT1 and added pin 5 of 4538 ( B - side) to start timer, then the pin 6 ( Q side) outputs high level, and VT2 gets conduction to drive relay K action its contacts are connected to the alarm device alarm. In the circuit, the timing time is determined by the time constant of RP1 and C1, R1 and C2 are used to prevent the erroneous operation of the timer when the power is turned on , LED1, LED2 and LED3 respectively show the power supply, sensor output and the operation of the relay.



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