Magnetic Reed Switch Sensor Module

A reed switch closes when a magnet comes near and opens when it moves away, which is a mechanically simple and reliably contact-based way to detect whether a door or window is open or closed - no line-of-sight requirement the way an optical sensor would need, and no ongoing power draw to hold state the way an active sensor might. This module wraps the bare reed switch with signal conditioning that gives a clean digital output plus an onboard LED that lights to confirm state, useful when first mounting and testing placement.

Because detection is purely magnetic proximity, mounting is straightforward: the switch goes on the frame, a small magnet goes on the moving door or window panel, and the two need only be within a few millimetres of each other when closed - no calibration or alignment beyond basic physical placement.

Common uses are door and window open/close detection for home security systems, cabinet or drawer sensors, and any project needing a simple, reliable binary proximity signal.