4x28 mm Magnetic Reed Switch – Large NO Switch for Automation, Security, and DIY

Technical Specifications and Applications of the 4x28 mm Reed Switch (Gold-Plated, Normally Open)

This magnetic reed switch is a compact non-contact magnetic sensor used for switching electrical circuits on and off using a magnet. In its default state (Normally Open), the switch contacts are open (circuit off) and will close (complete the circuit) when a magnetic field is applied near the switch, allowing current to flow.

The device features two ferromagnetic reeds sealed in a hermetic glass envelope, protecting the internal contacts and ensuring long-lasting, reliable operation.

Typical Features (for 4×28 mm reed switch):
✔ Size: approx. 4 mm diameter × 28 mm glass length — compact for tight applications;
✔ Contact Type: Normally Open (NO) — circuit closes in the presence of a magnetic field;
✔ Operating Voltage/Current: commonly suited for low-power voltages up to hundreds of volts and small currents (model dependent);
✔ Hermetically Sealed: glass body protects against dust and environmental contaminants;
✔ Non-contact Operation: minimal wear, long life.

Benefits:

• Simple and reliable magnetic activation with no power required;

• Minimal mechanical wear — extended service life;

• Compact form factor — ideal for small electronics projects;

Applications:
✔ Position and proximity sensors in security systems;
✔ Door/window open/close detectors;
✔ Home automation and IoT modules with microcontrollers;
✔ General non-contact circuit switching.