MC-38A Wired Magnetic Door Window Sensor NC/NO Reed Switch

Q: What is the difference between the Normally Open (NO) and Normally Closed (NC) reed switch configurations?

A Normally Open (NO) reed switch has contacts that remain open (circuit incomplete) when no magnet is present, and close (circuit completes) when a magnet is brought near. A Normally Closed (NC) reed switch is the opposite — contacts remain closed when no magnet is present, and open when a magnet approaches. Choose the configuration that matches your alarm controller's input requirements.

Q: How do I install the MC-38A magnetic door/window sensor?

Installation is straightforward. Attach the reed switch body to the door frame and the magnet to the door or window itself, aligning them within the 18 mm (±10 mm) actuating distance. You can secure both parts with the included screws or use double-sided tape for a tool-free, non-invasive mount. Connect the two wires from the sensor to your alarm panel or controller.

Q: What surfaces or door types can this sensor be used on?

The MC-38A is recommended for wooden doors and windows, but its compact size and flexible mounting method make it suitable for a wide range of door and window frame materials. Avoid mounting on thick metal surfaces, as ferromagnetic materials can interfere with the magnetic field and affect the actuating distance.

MC-38A Wired Magnetic Door Window Sensor NC/NO Reed Switch

$11.61 $13.80

MC-38A Wired Door & Window Magnetic Sensor Switch

Keep your home, office, or commercial space more secure with the MC-38A Wired Magnetic Door/Window Sensor. This compact reed switch sensor works with virtually any wired alarm system, triggering an alert the moment a monitored door or window is opened. Available in both Normally Open (NO) and Normally Closed (NC) configurations, it integrates seamlessly into new or existing security setups.

Made in Mainland China.

Key Features

Dual Output Options: Supports both Normally Open (NO) and Normally Closed (NC) operation — choose the configuration that fits your alarm controller.
Compact & Discreet: Slim 27 × 14 × 8 mm housing blends into door and window frames without drawing attention.
Easy Installation: Mount with screws or double-sided tape (SMD method) — no specialist tools required.
Reliable Reed Switch Technology: Magnetically actuated contacts offer stable, consistent performance over a long service life.
Durable Construction: Pressure-resistant, impact-resistant, and corrosion-resistant plastic housing built to last.
Wide Compatibility: Ideal for wooden doors, windows, cabinets, and more — suited for homes, hotels, shopping malls, warehouses, and hospitals.

Technical Specifications

Model	MC-38A
Material	Plastic
Switch Withstand Voltage	60 V DC
Load Current	150 mA
Dimensions	27 × 14 × 8 mm
Actuating Distance	18 mm ± 10 mm
Wire Length	~350 mm (24 AWG)
Switch Output	Normally Open (NO) / Normally Closed (NC)
Installation Method	Screw or double-sided tape (SMD)
Package Contents	1 × Sensor Set (switch body + magnet)

How It Works

The sensor consists of two parts: the reed switch body (mounted on the door frame) and the magnet (mounted on the moving door or window). When the door or window is closed, the magnet holds the reed contacts in their default state. When the door or window opens, the magnet moves away, changing the switch state — signalling your alarm panel to trigger an alert.

Normally Open (NO): Contacts are open with no magnet present; closing when the magnet is near. Circuit completes when the door/window is shut.
Normally Closed (NC): Contacts are closed with no magnet present; opening when the magnet approaches. Circuit breaks when the door/window is shut.

Application Ideas

This sensor is a versatile addition to any wired security or automation project:

Home entry doors and windows
Hotel room and emergency exit doors
Warehouse and storage room monitoring
Shopping mall and retail security systems
DIY Arduino / Raspberry Pi home automation projects

Frequently Asked Questions

Q: What is the difference between the Normally Open (NO) and Normally Closed (NC) reed switch configurations?

A: A Normally Open (NO) reed switch has contacts that remain open (circuit incomplete) when no magnet is present, and close (circuit completes) when a magnet is brought near. A Normally Closed (NC) reed switch is the opposite — contacts remain closed when no magnet is present, and open when a magnet approaches. Choose the configuration that matches your alarm controller's input requirements.

Q: How do I install the MC-38A magnetic door/window sensor?

A: Installation is straightforward. Attach the reed switch body to the door frame and the magnet to the door or window itself, aligning them within the 18 mm (±10 mm) actuating distance. You can secure both parts with the included screws or use double-sided tape for a tool-free, non-invasive mount. Connect the two wires from the sensor to your alarm panel or controller.

Q: Is the MC-38A sensor compatible with DIY alarm and smart home systems?

A: Yes. The MC-38A is a simple wired magnetic reed switch that outputs a contact closure signal, making it compatible with most wired alarm panels, DIY microcontroller projects (Arduino, Raspberry Pi), and home automation controllers that accept a dry contact or digital input.

Q: What surfaces or door types can this sensor be used on?

A: The MC-38A is recommended for wooden doors and windows, but its compact size and flexible mounting method make it suitable for a wide range of door and window frame materials. Avoid mounting on thick metal surfaces, as ferromagnetic materials can interfere with the magnetic field and affect the actuating distance.