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Security Alarm using PIR is an electronic security system that allows you to sense motion. It is used to detect motion whether a human has moved in or out of the sensor's range. Motion detector sensors are small, inexpensive, low-power-consuming, and easy to use. Due to these features, they are commonly used in gadgets and appliances used in homes or businesses. They are often known as PIR, “Motion detector”” Passive Infrared”, “Pyroelectric”, or “IR motion” sensors.
complete circuit diagram security alarm is given below. Any NPN transistor can be used to provide signals from PIR to the transistor.
Now we discuss the complete circuit and pins of the PIR sensor.
PIR sensors are basically made of a pyroelectric sensor, that can detect levels of infrared radiation. Everything emits some low-level radiation and hotter something emits more radiation. The sensor in a PIR is actually split into two halves. These two halves are wired up so that they cancel each other out. One half sees less or more IR radiation than the other, and the output will swing low or high.
The PIR sensors are more complicated than the other sensors. These sensors consist of Two slots made of a special material sensitive to IR. The Fresnel lens is used to see that the two slots of the PIR can see out past some distance. Inactive position, these two slots since the same amount of IR. The ambient amount radiates from the outdoors, walls or room, etc.
When any live thing like a human or animal passes by, it intercepts the PIR sensor's first slot a positive differential change between the two slots. When a human body or any animal leaves the sensing area, and then the sensor generates a negative differential change between the two lost. The IR sensor itself is housed in a hermetically sealed metal to improve humidity/temperature /noise or immunity.
Security Alarm Using PIR Sensor full video with structure is available please watch. video for more clearance and watching full functionality
We have learned about the PIR sensor above, and now we study a straightforward application of the PIR sensor. In the given circuit, we have used the PIR sensor as a motion detection circuit. As anything or a human passes IR energy or radiation generated, the infrared sensor detects the energy and immediately converts it into electrical pulses, which is enough to activate the transistor BC547 which activates the relay.
This project is opening and closing of doors automatically, in places wherein the presence of a person is mandatory for example, hotels, shopping malls, theaters, etc. this PIR sensor project is beneficial.
PIR sensors can be used in many more projects we have given the example of some famous projects.