Sensitive Hall sensor for wheel speed measurement

avandalen

100 W
Joined
Oct 2, 2010
Messages
175
Location
Maastricht, The Netherlands
Bicycle speed measurement is generally done with a spoke magnet and a reed relay sensor. If this is done on the rear wheel, there is a large spacing between the spoke magnet and the chain stay, where the sensor is mounted on. Therefore, the sensor has to be mounted on a relatively long bracket to minimize the distance. Since the sensor has to be adjusted precisely, this makes it vulnerable. With the use of a strong ring magnet and a sensitive Hall effect sensor, the distance is not critical anymore and the sensor can be mounted directly on the chain stay. A sensor-magnet distance of 30mm is allowed.
Hall-effect-speed-sensor.jpg

See more at my webiste:
http://www.avdweb.nl/solar-bike/mechanical-issues/hall-effect-bicycle-wheel-speed-sensor.html
 
You can also just stick another N52 magnet to the normal spoke magnet. It brings it a bit closer to the sensor and provides a much bigger magnetic field for it. It's own magnetism will hold it in place - no need for glue or anything like that.
 
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