KY-021 Mini Magnetic Reed Switch Module–NA

Description

About this item:

The KY-021 Mini Magnetic Reed Switch Module is a compact digital sensor designed to detect the presence of a magnetic field. At its core is a reed switch—a small glass tube containing ferromagnetic contacts that close when influenced by a nearby magnet. This action changes the module’s digital output state, making it function as a contactless switch.

Operating at 3.3V to 5V, the KY-021 is fully compatible with popular microcontrollers such as Arduino, ESP8266/ESP32, and Raspberry Pi. The module outputs a digital HIGH/LOW signal, simplifying integration into security alarms, smart home devices, and position-detection circuits.

With a typical activation distance of ≤10mm, its performance depends on the strength and proximity of the magnet used.

Key Specifications

• Operating Voltage: 3.3V – 5V DC

• Output Type: Digital (High/Low)

• Activation Distance: ≤10mm (depending on magnet strength)

• Contact Resistance: ≤100mΩ (initial)

Applications

• Door and window open/close sensors

• Security and alarm systems

• Position and proximity detection

• Robotics and automation

• DIY smart home projects