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I'm trying to build a speedometer for my motorcycle using an Arduino and I'm not sure whether to use a reed switch or a Hall sensor. The sensing distance is about 5-10 cm (the distance between the wheel and the sensor / switch). The only sensor I can get is a 3144 one (that's all the information I got about it...)

Is the distance too great for sensing? It only needs to check if the magnet is around the sensor, nothing more.

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  • \$\begingroup\$ Why such a large distance? \$\endgroup\$ – Andy aka Jun 6 '17 at 7:20
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    \$\begingroup\$ reed switches have moving parts that limit longevity and bandwidth. \$\endgroup\$ – dandavis Jun 6 '17 at 8:40
  • \$\begingroup\$ @Andyaka that s the closest safe distance that i can get between the fork and the wheel unfortunately \$\endgroup\$ – Andrei Grigore Jun 6 '17 at 8:41
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Hall sensor may be best; most are designed to be robust. Many have threads or mounting brackets to make it easier to attach to your system like this:

https://www.digikey.com/catalog/en/partgroup/gt1-series-hall-effect-gear-tooth-sensors/13172

As mentioned before, if you use magnets instead of detecting the metal passing by from a gear tooth or something, you can extend the range.

Reed switches rely on mechanical motion to send a pulse meaning some form of wear. They aren't designed to handle fast switching action over long periods of time.

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  • \$\begingroup\$ Interestingly, bicycle computers usually use reed switches, perhaps for long service life on a coin cell. But they tend to go slower with larger wheels, so a motorcycle may see a few times faster actuation frequency. \$\endgroup\$ – Chris Stratton Jun 9 '17 at 19:08
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A reed switch is not generally a good choice in a high vibration environment. Shocks may cause undesired closing of the switch. You could explore anti-vibration mounting, but it's basically the wrong solution.

A Hall effect sensor makes more sense here. 5cm is not too great a distance, finding magnets strong enough shouldn't be a problem.

You need more information than a partial part number to use a part properly. You're probably referring to the A3144. Google it and you'll find datasheets. The part seems to have been discontinued, by the way.

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