HW-072 Reed Switch Magnetic Sensor Module with LM393

The HW-072 is a reed switch magnetic sensor module built around the LM393 comparator. At its core is a normally open reed switch sealed inside a glass capsule filled with inert gas (rhodium), which closes when a magnetic field approaches and opens again when the field is removed. The module converts this mechanical action into a clean digital output (0 or 1), with a potentiometer for sensitivity adjustment and two indicator LEDs for power and switching status. It operates on a 3.3V to 5V DC supply and can drive more than 15mA, making it suitable for direct connection to Arduino, ESP32, Raspberry Pi, and other microcontrollers. The compact 32 × 14 mm PCB includes mounting holes for easy installation. This magnetic sensor module is widely used in door and window magnetic switches, programmable switches, photocopiers, washing machines, refrigerators, electromagnetic relays, and liquid level meters. The reed switch module detects magnets within approximately 1.5cm, and the sensitivity can be fine-tuned via the onboard potentiometer. With its clean waveform and stable performance, the HW-072 provides reliable magnetic field detection for both hobbyist and industrial projects.