HC-SR505 Mini Infrared PIR Motion Sensor Infrared Detector Module

This ultrasonic sensor module is used to detect the motion of a body that emits infrared radiations. This sensor module powered from a DC power source ranges from +5V to +20V.  And the device response or output is connected to a LED to visualize the device response. This is perfect for use in battery-operated systems since the device is specifically designed to operate by consuming very little power. Because of its small size, the module is installed in applications where the system size is taken into consideration.

A Passive Infrared sensor is defined as an electrical sensor that detects the infrared light radiated by a warm object or used to sense motion. It is widely used to detect the motion of a human body within the sensor’s range. Hence often referred to as “PIR”, “Pyroelectric”, “Passive Infrared” and “IR Motion” sensor. By simply connecting the power to the module, HC-SR505 is installed in any system easily and receive a response from it.

The module consists of an onboard pyroelectric sensor, conditioning circuitry, and a dome-shaped Fresnel lens. In addition to it, it consists of a delay time adjustment Potentiometer and sensitivity adjustment Potentiometer. These pyroelectric sensors introduce changes in their temperature due to incident infrared radiation into an electric signal. But there will be no change in the detection distance. In order to lengthen the detection distance of the detector, an optical system was added to collect the infrared radiation. Usually, a plastic optical reflection system or plastic Fresnel lens used as a focusing system for infrared radiation. These small, inexpensive, low-power sensors can be easily interfaced with ARDUINO, RASPBERRY PI, AVR, PIC, 8051, etc.

PIR sensor senses infrared energy emits the human body within a detection area of approximately 3-7 meters. Under normal conditions, the sensor output will provide a LOW at the output pin. So when the does not detect any IR (Infra-Red) radiation and unmoving things the output will be LOW and the LED will be OFF. In case if a human or a dog passes through its detecting area opposite to its lens, the module will detect the change in the IR radiation (as the living body emits IR radiation) and as a response provides HIGH logic at the output pin. So when the device detects a living body or IR emitting things the output switches from LOW to HIGH and the LED will get turned ON.