KY-025 Reed Switch Module

The KY-025 is a reed switch sensor module that detects the presence of a magnetic field and delivers both digital and analog output signals. At its core is a reed switch — a pair of ferromagnetic contacts sealed in a glass tube — that closes when exposed to a sufficiently strong magnetic field and opens when the field is removed. This makes it ideal for non-contact detection applications where reliability and simplicity are essential.

The module features a 4-pin interface providing separate digital and analog outputs, along with an onboard LED indicator that lights up when the switch is triggered. The built-in sensitivity adjustment potentiometer allows fine-tuning of the digital trigger threshold to suit varying magnet strengths and distances.

Compatible with Arduino, ESP8266, ESP32, STM32, and Raspberry Pi platforms, the KY-025 is widely used in door and window security sensors, proximity detection systems, flow meters, anti-tamper mechanisms, and smart home automation projects.

Its straightforward wiring, dual output capability, and adjustable sensitivity make it a versatile and reliable choice for hobbyists and professionals alike.

Specification:

• Sensor Type : Reed Switch
• Output Type : Digital + Analog
• Operating Voltage : 3.3V – 5V DC
• Onboard LED Indicator : Yes
• Sensitivity Adjustment : Potentiometer (onboard)
• Digital Output : HIGH / LOW
• Pins : 4 (AO, DO, GND, VCC)
• Compatible Boards : Arduino, ESP8266, ESP32, STM32
• PCB Dimensions : 15 × 36 mm