The KY-021 Mini Reed Sensor Module is a compact magnetic switch sensor designed for Arduino, ESP32, ESP8266, Raspberry Pi, STM32, and other microcontroller platforms. Based on a reed contact switch, this module detects the presence of a magnetic field and outputs a digital signal, making it ideal for security systems, door and window monitoring, position detection, automation projects, and robotics applications.

When a magnet comes close to the sensor, the reed switch closes and changes the output state, allowing microcontrollers to detect movement, position, opening, or closing events. Its low power consumption, compact size, and simple digital interface make it a popular choice for DIY electronics, industrial automation, smart home projects, and educational learning.

Features:

• High-quality KY-021 magnetic reed switch module

• Universal magnetic contact sensor

• Reliable reed switch technology

• Digital output signal for microcontroller interfacing

• Detects magnetic field presence accurately

• Low power consumption design

• Compact and lightweight construction

• Fast response time

• Stable and long-lasting performance

• Easy connection with Arduino and development boards

• Suitable for security and automation applications

• Compatible with 3.3V and 5V systems

• Ideal for door, window, and position detection

• Simple plug-and-play operation

BDTronics supplies quality-tested Arduino sensors, robotics components, and electronic modules for students, makers, engineers, and automation professionals. The KY-021 Reed Sensor Module is selected for dependable magnetic detection and easy integration into embedded systems and smart automation projects.

Specifications:

• Model: KY-021

• Sensor Type: Magnetic Reed Switch

• Operating Voltage: 3.3V – 5V DC

• Output Type: Digital

• Detection Method: Magnetic Field Detection

• Weight: 2g

• Module Size: Compact Design

• Package Size: 3.00cm × 2.00cm × 1.00cm

• Compatibility: Arduino, ESP32, ESP8266, Raspberry Pi, STM32, AVR, PIC Microcontrollers

Pin Configuration:

• VCC: Power Supply (3.3V–5V)

• GND: Ground

• S: Digital Signal Output

How to Use:

• Connect VCC to 3.3V or 5V power supply

• Connect GND to system ground

• Connect signal pin to a digital input pin of the microcontroller

• Place a magnet near the reed switch sensor

• Monitor the digital output state in your program

• Trigger actions based on magnet detection events

• Use for open/close detection, counting, or automation control

Applications:

• Door open/close detection

• Window security systems

• Smart home automation

• Magnetic position sensing

• Alarm systems

• Industrial automation

• Robotics projects

• Object detection systems

• Access control systems

• Machine position monitoring

• Electronic locking systems

• Arduino DIY projects

• Educational electronics learning

• Counter and trigger applications

• IoT monitoring systems

Advantages:

• Simple digital output

• Compact and lightweight

• Low power consumption

• Long mechanical life

• Reliable magnetic detection

• Easy installation

• Compatible with most microcontrollers

• Cost-effective sensing solution

Package Includes:

• 1 × KY-021 Mini Reed Sensor Module

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