How does the PIR Motion Sensor Module – SR501 work?

Wednesday, June 21, 2023 Category:

The SR501 PIR Motion Sensor Module works based on the principle of detecting changes in infrared radiation emitted by living organisms. Here’s a simplified explanation of its operation:

The module includes a pyroelectric sensor that can detect small changes in infrared radiation.
When a human or warm-blooded animal moves within the sensor’s range, it emits infrared radiation that changes the temperature pattern in its surroundings.
The Fresnel lens on the module focuses the infrared radiation onto the pyroelectric sensor.
The sensor converts the detected changes in infrared radiation into electrical signals.
The supporting circuitry amplifies and processes the electrical signals to determine the presence of motion.
The module provides a digital output signal that indicates motion detection, which can be used to trigger actions or control other devices.