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Hall effect sensors

I am looking to upgrade a project I built last year. The project involved modifying an elliptical cross trainer to control the playback speed of an MP3 being played on a Raspberry Pi.

It was done with some custom python code and a hall effect sensor.

I am now looking to do the same thing with a real bike. But the use of a ‘normal’ bike means that I am looking to use the standard spoke-mounted magnet from a bike computer kit. The one I have needs to be within a few millimetres of the sensor.

If the sensor I am currently using is one of these:

Am I right in assuming it should be possible to get a more-sensitive sensor, rather than trying to mount a stronger magnet to the spoke? If so, which one would be recommended?


Hi Michael,

That sounds like a pretty neat project!

I’ve taken a look at the datasheet on the product page you linked to:

Looks like you need something with a B_op of less than 70 Gauss. I’d suggest using one of these:

And here’s the relevant section from the datasheet:

You could also just use stronger magnets, or move them closer. I’d also suggest considering adding multiple magnets evenly spaced around the wheel to improve your system’s sensitivity to acceleration.

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