How to Use a Magnetic Door Switch / Sensor With Arduino

About: Arduino Tutorials by Team

In this tutorial we will use one magnetic - contact door sw / sensor and a buzzer for making a "noise" when a door is opened. Normally the reed is 'open' (no connection between the two wires). The other half is a magnet. When the magnet is less than 13mm (0.5") away, the reed switch closes.

Step 1: What You Will Need

For this project you will need:

  • Arduino uno
  • Magnetic Contact Switch - Door Sensor
  • Buzzer
  • Breadboard and some cables

Step 2: The Circuit

The connections are pretty easy, see the above image with the breadboard circuit schematic.

Step 3: The Code

Here's the code, embedded using Codebender!

Try downloading the Codebender plugin and clicking on the "Run on Arduino" button to program your Arduino board with this sketch. And that's it, you've programmed your Arduino with this sketch!

Step 4: Well Done!

You have successfully completed one more "How to" tutorial and you learned how to use a magnetic contact switch with Arduino.

I hope you liked this, let me know in the comments.

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    5 Discussions


    Question 1 year ago on Step 1

    what types of using magnetic Switch?


    1 year ago

    I need to change

    int state; // 0 close - 1 open wwitch


    int state; // 1 close - 0 open wwitch.

    How do I alter the code? Please help.

    This is for my wardrobe light. I just swapped the buzzer for an led.

    1 reply

    Reply 1 year ago

    use PNP transistor for switching


    1 year ago

    Thank you! Great tutorial.

    Do you have any thoughts about how long the sensor wire can be?

    1 reply