I can think of all sorts of uses for this, a DIY speedometer and odometer that is cheap to make too.  I’m thinking of the kids, and how they love being out on the bikes. I might even fit one on the shopping trolley lol!  Electroguyz have posted the tutorial on indistructables.



The working of a project is simple. It is also very important to understand it for making the project. Basically the apparatus consists of the reed switch or the magnetic switch mounted on the frame of the cycle and a magnet mounted on the one of the spokes. As the wheel rotates the magnet triggers the switch every rotation. The signal go to the arduino which counts the no of rotation and finds the distance covered(you have to pre-enter the diameter of your cycle). The arduino also measures the time and calculates the speed. The output from the arduino then goes to the lcd where it is shown in miles per hour (you can convert it if you want).

The full project would cost you about 5$-10$ depending on the place you live in. The cycle speedometer also would require moderate soldering skills and an afternoon. so without any further ado the materials for the build are –:

1. The arduino board – i got Rs.330 which is around 5$ but to programme the pro mini you will also need to have an arduino uno or an usb to ttl adapter (how to program an arduino pro mini with an uno) or if you don’t have it then use an arduino micro or an arduino uno.

2.Arduino 16×2 lcd (Rs150 or 2.3 $)

3.7805 voltage regulator (increases the control over the contrast no major difference -optional)

4. 2x switches for backlight and on off (optional)

5.220 ohm resistor

6. trimer pot 10k ohm

7.female headers and male headers if you want the reed switch to be detachable

8. reed switch


10. a momentary switch to change the modes

11. 0.1uf capacitor to reduce the debounce of the button

12.10k ohm resistor

The tools you would require are

1. soldering iron


3. enclosure

4. cutting tool like the Dremel to cut out holes in the enclosure to mount he lcd and stuff

5. hot glue or any adhesive to mount the various components.

Read the full article here and discover how to make this.


Brilliant project.  This is a perfect opportunity to get the kids involved and improve their cognitive skills. The fact that it is a Arduino speedometer, means you can really let your imagination run free. If any of you decide to take on this DIY speedometer and odometer project would love to hear from you

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