Cre8-Range-Human body sensing IR pyroelectric infrared sensor anti-theft alarm electronic kit students electronic principle study HC-SR501

Passive infrared (PIR) sensors use a pair of pyroelectric sensors to detect heat energy in the surrounding environment. The Pyroelectric infrared sensor anti-theft circuit is composed of pyroelectric infrared sensor PIR, integrated operational amplifier LM393, 110 alarm circuit and starting delay circuit. The circuit can be protect against theft. When the family leaves bedroom, switch K1 is closed, the circuit begins to work . As long as  someone enters the room for a period of time, it will sound the alarm. Passive Infrared Radiation (PIR) sensor detects the change in infrared radiation of warm blooded moving object in its detection range.