Magnetic Reed Switch Module KY-025

Magnetic Reed Switch Module KY-025

Modules
DET575
Part.No: KY-025
€2.50
In Stock
Immediate Dispatch
KY-025 Magnetic Reed Switch Module with LM393 comparator, digital output (0/1), operating voltage 3.3V–5V. Compatible with Arduino, ESP32, and Raspberry Pi projects. Ideal for detecting magnetic fields in door/window sensors, relays, and automation systems.

 

The KY-025 Magnetic Reed Switch Module (MPN: KY-025) is a compact, easy-to-use sensor module that detects the presence of a magnetic field and outputs a clean digital signal (HIGH/LOW). Built around the industry-standard LM393 voltage comparator, it operates across a wide voltage range (3.3V–5V), making it natively compatible with Arduino, ESP32, and Raspberry Pi platforms without any level-shifting. When a magnet approaches the reed switch, the internal glass-encapsulated contacts close, triggering a digital state change on the output pin — perfect for non-contact switching applications.

Key Features

  • LM393 Wide-Voltage Comparator: Ensures a clean, stable output waveform across both 3.3V and 5V logic systems → no signal noise or false triggers
  • Digital Switching Output (0 and 1): Outputs a clear HIGH or LOW signal → directly readable by any microcontroller digital pin
  • Drive Capability >15mA: Strong enough to drive LEDs, optocouplers, or small relays directly → no external transistor needed for many applications
  • Wide Operating Voltage 3.3V–5V: Works with 5V Arduino boards and 3.3V ESP32/Raspberry Pi → universal compatibility
  • Mounting Hole: Fixed bolt hole on the PCB → easy and secure installation in enclosures or panels
  • Compact PCB (3.2cm × 1.4cm): Small footprint → fits in tight spaces and DIY enclosures

Pinout & Wiring

PINSymbolDescription
1VCCPower supply input — connect to 3.3V or 5V
2GNDGround — connect to GND on your microcontroller
3DODigital Output — HIGH when no magnet detected, LOW when magnet is present (or vice versa depending on orientation)

Wiring note: Connect VCC and GND to your board's power rails, then read the DO pin with any digital input pin on your microcontroller. No pull-up resistors are required — the LM393 comparator handles the output conditioning internally.

Compatibility

  • Arduino UNO / Nano / Mega (5V): Fully compatible — connect VCC to 5V and read DO on any digital pin.
  • ESP32 / ESP8266 (3.3V): Fully compatible — connect VCC to 3.3V; the LM393's wide-voltage design handles 3.3V logic natively.
  • Raspberry Pi (3.3V GPIO): Compatible at 3.3V — use a GPIO input pin to read the digital output.

Typical Applications

  • Door & Window Sensors: Detect opening/closing events in home automation or security systems — attach a magnet to the door and the module to the frame.
  • Electromagnetic Relay Control: Use as a contactless trigger to activate relay modules in industrial or hobbyist switching circuits.
  • Appliance Integration: Suitable for use in washing machines, refrigerators, cameras, disinfection cabinets, and other program-controlled devices.
  • Utility Metering: Can be used in gas meters, water meters, and level meters to detect reed-based counting pulses.
  • Electronic Weighing & Position Detection: Detects the presence or absence of a magnetic marker in weighing scales or position-sensing fixtures.

Technical Specifications

Output TypeDigital switching output (0 and 1)
Comparator ICLM393 (wide voltage)
Operating Voltage3.3V – 5V
Output Drive Current>15mA
PCB Dimensions3.2cm × 1.4cm
Mounting1× fixed bolt hole
MPNKY-025

FAQ

Q: Does the KY-025 require an external pull-up resistor on the DO pin?
A: No. The onboard LM393 comparator conditions the output signal internally, so you can connect DO directly to your microcontroller's digital input pin without additional components.

Q: How close does the magnet need to be to trigger the reed switch?
A: The activation distance depends on the magnet's strength. Typically, a standard neodymium or ferrite magnet will trigger the reed switch within a few millimetres to ~1–2cm. Test with your specific magnet for reliable results.

Package Contents: 1× KY-025 Magnetic Reed Switch Module

⚠ Note: A magnet is not included with this module. Ensure the magnet used is positioned correctly relative to the reed switch for reliable triggering. Avoid exposing the glass reed switch element to mechanical shock or excessive force.
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