ITEM NAME:DIY Pyroelectric Infrared Sensor Kits Anti-Theft Circuit Electronic Techno RNO Descriptio n Description: Material: PCB Color: blue Size: 84 mm * 44 mm Weight: 55 g Function: The infrared sensor of pyroelectricity is composed of PIR, integrated operational amplifier LM358, voltage comparator LM393, 110 alarm circuit and startup delay circuit. The circuit can be used to guard against theft. When family leaves the bedroom, switch K1 is closed, circuit begins to work. As long as someone enters the room after a period of time, will sound the alarm. 1. After the circuit is electrified, when the infrared signal emitted by the human body in front is detected by the pyroelectric infrared sensor PIR, the weak electrical signal is output by PIR "2" pin. After being amplified by the transistor VT1, the high gain and low noise are amplified by C2 to the "3" pin of the operational amplifier IC2A, and then the signal is output by the "1" pin of IC2A. 2. As a voltage comparator in the circuit, the "5" pin of IC2B is provided with reference voltage by R10 and VD1. When the signal output from the "1" pin of IC2A reaches the "6" pin of IC2B, the input voltage of "5" and "6" pin is compared. C6 through VD2 discharge, make the IC3 "2" feet into a low level, if the voltage than "2" feet "3" feet by resistance R14, R15 low partial pressure to provide the benchmark voltage, is the "1" the IC3 feet into a high level, the transistor VT2 conduction, music chip IC4 voltage, the output of audio signal "2" foot after VT4 transistor amplifier, drive buzzer BELL sent 110 alarm sounds. 3. When people leave the detection area, the "7" pin of IC2B becomes high level, VD2 closes off, and C6 has a charging time (30 seconds), which makes the buzzer delay alarm for 30 seconds. 4. VT3, R20 and C7 constitute the startup delay circuit, which takes about 2 minutes (should be greater than the delay alarm time) to prevent the alarm immediately upon startup, leaving time for people to leave the site, .After the circuit is electrified, when the infrared signal emitted by the human body in front is detected by the pyroelectric infrared sensor PIR, the weak electrical signal is output by PIR "2" pin.
