Hall Effect Gear Tooth Sensor

[Jay Monkman]

Previously MTN-KAT babbled:

> I don't know that you'd be able to magnetize the ring-gear teeth in a uniform
> manner that would result in all of the teeth having the proper polarity.

Is that really necessary? I was looking through Allegro's application 
notes, and they showed a hall-effect sensor between a metal gear and
a magnet. I didn't see any mention of the gear being magnetized. 
I tested it sort of. I used a magnet, the sensor, and a small screw.
I could see the signal change as I moved the screw over the sensor.
I hope that we won't need to magnetize the gear.



Jay Monkman	    The truth knocks on the door and you say "Go away, I'm 
monkman at uiuc.edu    looking for the truth," and so it goes away. Puzzling.
		     - from _Zen_and_the_Art_of_Motorcycle_Maintenance_