Mini Reed Switch Module - KY-021 - Server On The Move
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Mini Reed Switch Module - KY-021

Vendor: Server On The Move
SKU: KY-021
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The Mini Reed Switch Module uses a sensor which reacts to magnetic fields. Without a magnetic field the switch remains open, move magnet close and the switch will close.

We put the reed switch onto a module for your convenience to easily use in your projects where the change of a magnetic field needs to detected.

A Mini Reed Switch is often used in security - paired with a  magnet - to indicate if something has been opened (door, window, etc.).

Connect the minus to GND from your board and the middle pin to your source (e.g. 5V from your board). Read S pin (e.g. via digital pin on your Arduino) to detect the open/close state of the switch.

This Mini Reed Switch Module contains an onboard 10k Ohm Resistor, so there is need for any additional components to use it.


  • 3-5.5V DC
  • Bolt holes
  • Three pins (GND (-), VCC (middle pin), Sensor (S))


For Arduino see here