How Does a Pir Sensor Work?

In today's Instructable we will be going to talk about the working of Passive Infrared Sensors or PIR Sensors.

The Pir Sensor is very different from the Active Infrared Sensors in just a simple way. The Active sensors consist of a transmitter as well as the receiver However Pir sensors involve only the receiver as it detects the heat from the object motion or the object in front of it. The Reference Image Of Pir Sensor is Attached Below:

1. A Pir Sensor

Well Yeah, what else do you think we will need?

PIR is made of a pyroelectric sensor. As discussed above the Pir Sensors consist of The Reciever part only so not transmitting is there rather receiving is there. They also have a wide detection angle and are covered by a fresnel lens on top that allows the detection of a wider area rather than focusing only on a particular region or area. This is why they are commonly used in Burglar Alarm systems for motion detection.

It receives infrared radiations from a moving body like a Human and when that happens the sensor detects it. Fun Fact: Any objects that have a certain temperature emit infrared radiation to the outside world.

Whenever motion is detected the sensor gives the Output to the microcontroller that whether a motion is detected or not. If it is detected the Microcontroller then performs necessary actions mentioned predefined in the codebase, In this way a buzzer or alarm can be played whenever a burglar enters a location.

You might be wondering that well the idea of the PIR sensors sounds cool to me but how about its detection range as if I would like to use it for my project or any other purposes I would need to consider that as well.

Don't worry I got your back. So now let's talk about the detection range of the Pir Sensors

The detection for a paired sensor like the one which we are using is Around ranges from 25 cm to 20 m.

The Range may vary depending on Certain conditions like the size as well as the manufacturer of the sensors.

Now as you might have known that how PIR sensors work now you might be excited to know where you can actually use them in real life.

Here are a few places where you can use Pir Sensors

1. Burglar Alarms
2. Motion Sensors
3. Automatic Door Systems
4. Automatic Lights
5. Smart Home Systems