Looking for a wheel speed sensor...

[Peter Orban]

> From: Chris Howard <choward at extro.ucc.su.oz.au>

> I'm currently building a data logger for a thesis project and I need a wheel
> speed sensor. I'm thinking of using a proximity sensor with a magnetic
> trigger on the front hub. Does anyone know of a suitable sensor and where I
> could get one from ? (I'm in Sydney but anywhere will do!)

Industrial automation uses proximity switches, so any place that builds or
services systems like that would have magnetic proximity sensors.
You can also ask for a sample from a distributor. Check the Yellow pages
in the phone book.

A speed sensor can be attached to the speedometer itself, detecting the
rotating magnet of the meter. A coil pick-up or a Hall-sensor would do.
The cars with cruise control usually have that sensor already built in.
Alternatively, you can sense the speed of the engine from the ignition,
and calculate the wheel speed based on the gear ratio. If you can limit
your data collection when you or the car does not change gear, that might
do too.
These are not really wheel speed sensors, but it might work for you,
depending what you want to use the information for.

Good luck, Peter
--
Peter Orban
National Research Council of Canada
Internet: peter.orban at nrc.ca