Hall Effect Gear Tooth Sensor

[Jim Pieronek]

MTN-KAT writes:

[Much appreciated commendation snipped for sake of brevity.]

 > I also looked at the booklet that I had ordered with my Panasonic Hall Effect
 > sensors, every application description shows the sensor in a stand-alone 
 > design. They are all merely simple magnetic switches without anything even
 > vaguely resembling the above diagram. Maybe they don't understand either? :):)

I have noticed this in TI's data books.  Their examples have a Hall
effect sensor wedged into a gap in a torroidal coil.

Perhaps the tooth-counting application that we are engaged in is a bit
of a niche compared to all of the applications of these devices.
Another reason that they may leave applications like this out is that
they require some understanding of magnetic circuits, and that would
require them to add another page or two to the app notes.

Finally, I now recall where I saw the "Hall Effect Sensor in a Tube"
that I mentioned in a previous post.  I worked for GM on the Quad-4
engine.  It has (at least the pre-production units _had_) a crankshaft
position Hall Effect sensor.  There was a balancing wheel cast in the
shaft between cylinders 2 and 3.  It was about 6 inches in diameter
and 3/4 inch thick as I recall (10 years ago now).  The wheel had a
machined rim that had six equally-spaced slots cut in it (about 1/16
inch wide & deep) and one extra slot cut near the TDC slot.  The short
interval between the TDC slot and the sync slot was used to sync the
computer to the engine.  The sensor was shoved into a hole in the
block that put it right where it needed to be.

I'm going to visit my friendly auto parts store and see if they sell
those sensors.  They ought to work great on the ring gear.  I'll
report my findings next week.

Jim