Reed Switch Sensor Module, Magnetic Proximity Detection

A reed switch detects the presence of a nearby magnetic field through a genuinely simple mechanism: two ferrous metal reeds sealed inside a glass envelope flex together and close an electrical circuit when a magnet comes close enough, then spring back open the moment the magnet moves away - no power needed for the sensing element itself, just a passive mechanical response to magnetic field strength.

This module mounts that bare glass reed switch onto a breakout board with a comparator circuit, converting the switch's raw mechanical open/close behavior into a clean digital output signal that a microcontroller can read reliably, with the comparator specifically credited with giving a clean waveform and strong driving ability compared to reading the bare switch contacts directly. Operating voltage spans 3.3 to 5V, and the switch itself can handle up to 1.2A through its contacts, giving some headroom beyond pure logic-level signaling.

A mounting bolt hole lets the module be fastened securely in place - a genuinely important detail for a sensor whose entire job depends on maintaining a consistent, predictable distance from whatever magnet it's meant to detect, whether that's a door-frame-mounted switch and a door-mounted magnet, or a position sensor on a moving mechanism.

Builders working on a door or window open/close alarm, a lid-position sensor, a simple proximity-triggered switch, or any project needing basic magnetic presence detection without active power draw on the sensing element itself will find this reed switch module a well-proven, low-power solution for that specific sensing task.