Magnetic Reed Switch Door Sensor with Wire MC-38A Surface-Mount Magnetic Alarm Sensor(White)

The MC-38A is a compact, surface-mount magnetic reed switch sensor designed for detecting the opening and closing of doors, windows, or cabinets. It is widely used in home security systems, DIY electronics, and smart automation setups. The sensor operates on a Normally Closed (NC) principle—meaning the circuit remains closed when the magnet is nearby, and opens when the magnet is separated, triggering an alert or action.

This sensor consists of two components: the reed switch unit and a matching magnetic block. When installed in alignment (typically on a door frame and the moving door), the magnetic field keeps the circuit closed. As soon as the door opens and the magnet moves away, the circuit breaks—ideal for intrusion detection or triggering smart home routines.

Constructed from durable ABS plastic, the sensor has a compact footprint, making it easy to install discreetly using either screws or the included double-sided adhesive. The attached wires are non-polarized, simplifying connection to microcontrollers, alarm systems, or relays.

Key Features

• Normally Closed (NC) configuration – triggers when the magnet is moved away
• Compact ABS plastic housing for low-profile mounting
• Easy surface installation using screws or adhesive tape
• Comes with a paired magnetic block for activation
• Includes approximately 30 cm of non-polarized wire leads for easy electrical connection
• Rated for low-voltage applications up to 100–110 V DC
• Typical actuation distance of 15 mm to 25 mm
• Ideal for security systems, smart automation, and DIY electronics
• Reed switch mechanism requires no standby power
• Lightweight design (approximately 10 grams per unit)

Technical Specifications

• Model: MC-38A
• Contact Type: Normally Closed (NC)
• Housing Material: ABS plastic
• Dimensions: ~27 mm × 14 mm × 8 mm (L × W × H)
• Wire Length: Approx. 30 cm (2-wire cable)
• Rated Voltage: Up to 100–110 V DC
• Rated Current: Up to 0.5 A
• Max Switching Power: Up to 10 W
• Actuation Distance: 15–25 mm (typical)
• Mounting: Surface-mounted (screws or tape)
• Weight: Approx. 10 grams
• Polarity: Non-polarized wiring
• Use Environment: Indoor/dry locations only