All of us have overwhelmed watching those incredibly breath-taking futuristic rooms and halls in movie scenes with all those different sensors. It’s really motivational for tech-savvy guys to watch those scenes and try them out in real. Now we are going to show you how to make a motion sensor alarm circuit easily with the help of PIR module.
This simple PIR security circuit can detect human presence in an area and produce sound alerts. PIR is basically an infrared motion detector sensor module and is the core component used here. It is able to detect motion within a range of 7 meters, the detection range and alerting duration can be adjusted as per your needs.
By combining this infrared detector with the other sensor circuits which we have already published and setting them up in your room, you can also surprise your family and friends. Typical applications are home security systems and bank security system. As an extension of this one, we will also publish a PIR motion sensor switch for lighting.
Motion Sensor Alarm Circuit Diagram
- Transistor (BC548)
- Buzzer (5V)
- PIR Sensor
- PIR (Passive Infrared Sensor) measures the infrared (IR) light radiating from objects.\
- Human body emits heat energy in the form of radiation and it’s invisible to human eyes as they are IR waves.
- PIR is designed to detect these waves. You can refer passive infrared sensor datasheet to know more about PIR motion sensors.
- PIR module has three pins- GND, OUT and VCC. Output it active high and it’s connected to base of NPN transistor BC 548.
- When the PIR detects movement, the output pin become high and base pin of transistor get a positive voltage which in turn makes the transistor ON.
- When the transistor is ON it will conduct and as a result buzzer gets negative supply turning it ON.
- The ON time of the buzzer or PIR output (HIGH time) can be adjusted from 5 seconds to 300 seconds by simply rotating the preset attached with the module.
- Also it has another preset to adjust the distance or sensitivity from 3 meters to 7 meters.
Hope you enjoyed this circuit, and let us know if you have any queries through comments below.