HC-SR501 PIR Motion Sensor Module

The HC-SR501 PIR Motion Sensor Module is one of the most widely used motion detection modules for electronics projects, automation systems and security prototypes. It uses a passive infrared sensing element with a Fresnel lens to detect changes in infrared radiation caused by a moving human body, pet or warm object. When motion is detected, the module drives its OUT pin HIGH, typically around 3.3V; when no motion is present, the output remains LOW. This makes it easy to connect directly to microcontrollers such as Arduino Uno, Nano, ESP32, ESP8266, Raspberry Pi GPIO with suitable logic handling, and other embedded control boards. The module is based on the BISS0001 PIR controller circuit and supports a wide DC supply range of approximately 4.5V to 20V, making it convenient for both 5V hobby circuits and higher-voltage control panels. Two onboard potentiometers allow the user to adjust sensing distance and output delay time. A trigger mode jumper is also provided on most HC-SR501 boards: H mode enables repeatable triggering, while L mode gives a non-repeatable single trigger during the delay period. This HC-SR501 PIR sensor is suitable for automatic room lights, burglar alarms, visitor counters, smart home occupancy detection, toilet/bathroom light controllers, energy-saving systems and IoT motion alerts. It offers a practical detection range of about 3m to 7m depending on adjustment, mounting height, ambient temperature and target movement. For best results, mount the white dome lens facing the monitored area and avoid direct sunlight, heaters, fans or rapidly changing thermal sources. In the box: 1 x HC-SR501 PIR Motion Sensor Module. Pin notes: VCC accepts DC supply, OUT is the digital motion output, and GND connects to common ground.