• Dual Contact Type – NO / NC Output
• 3 Screw Terminal Connection
• Reliable Magnetic Reed Switch
• Durable ABS Plastic Housing
• Surface Mount Easy Installation
• Compatible with Alarm & Access Control Systems
The DH-31 NO/NC Door Contact (3 Screw) is a magnetic sensor designed for security alarm and access control systems to detect door or window opening.
This model includes three screw terminals, allowing both Normally Open (NO) and Normally Closed (NC) configurations from the same sensor. This flexibility makes it suitable for different alarm panel wiring requirements.
The device consists of a magnetic reed switch and a magnet. When the door is closed, the magnet keeps the sensor in its normal state. When the door opens and the magnet moves away, the contact changes state and sends a signal to the alarm panel. Magnetic door contacts like the MC-31 series are commonly used in wired alarm systems and typically detect door gaps around 15–25 mm depending on installation.
Its compact design and durable ABS casing allow installation on wooden, aluminum, or metal doors and windows.
Product Type: Magnetic Door Contact Sensor
Model: DH-31
Contact Type: NO / NC (Selectable)
Terminal Type: 3 Screw Terminal
Operating Voltage: Up to 100V DC/AC
Max Switching Current: 0.5A
Max Power Load: 10W
Operating Gap: 15–25 mm
Material: ABS Plastic
Connection Type: Wired
Installation Type: Surface Mount
Usage: Indoor
Application: Alarm & Security Systems
Home Security Systems
Burglar Alarm Systems
Access Control Systems
Office Doors
Window Security
Warehouses
Commercial Buildings
Smart Alarm Installations
Product Type: Magnetic Door Contact Sensor
Model: DH-31
Contact Type: NO / NC (Selectable)
Terminal Type: 3 Screw Terminal
Operating Voltage: Up to 100V DC/AC
Max Switching Current: 0.5A
Max Power Load: 10W
Operating Gap: 15–25 mm
Material: ABS Plastic
Connection Type: Wired
Installation Type: Surface Mount
Usage: Indoor
Application: Alarm & Security Systems
Home Security Systems
Burglar Alarm Systems
Access Control Systems
Office Doors
Window Security
Warehouses
Commercial Buildings
Smart Alarm Installations
Q1: What is the advantage of the 3-screw terminal?
It allows both NO and NC connections, giving flexible wiring options.
Q2: Can it be used on windows?
Yes, it works for both doors and windows.
Q3: Is it compatible with alarm systems?
Yes, it works with most wired alarm panels.
Q4: What is the detection gap?
Typically around 15–25 mm depending on installation.
Q5: Is installation difficult?
No, it is a simple surface-mount sensor installed with screws.
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