? on Mr Hall Effect

[Clarence L.Snyder]

Roger Heflin wrote:
> 
> I think the teeth improve the magnetic coupling between the powered
> coil and the signal coil.   I would almost guess that the powered coil
> was powered by something other than a DC signal.  Basically the power
> coil to the signal coil is a transformer and putting the metal near it
> changes how the transformer acts and that is what is detected.
> 
> I do not think a DVM would be able to detect the signal good enough.
> There would be only one change when you moved it in closer, and that
> would pass by the DVM way too fast to catch.
> 
> All of those devices work on transients that are probably too fast to
> catch with a DVM.  If you have it, you may try feeding it into a sound
> card and see what the wave really looks like.  Also if you where
> spinning the disk past the sensor you would be able to detect the
> level out the output signal (average level) changing, but would owuld
> not be able to detect any of the waveforms themselves.  You might in
> the case be able to put the DVM on HZ (if yours had this) and count
> the number of teeth.
> 
>                         Roger
> 
>  On Tue, 10 Nov 1998, Bruce Plecan wrote:
> 
> > In the past, I done some trouble shooting with Hall Effect Devises.
> > Now, for the first time I hooked a meter to one with it sitting on the
> > table.  The one I'm starring at is a Toyota, it has a red lead, a white
> > lead, and a sheilded cable with ground.
> >   So being the Cone Shaped Hat Wearer that I am, I did the following.  Using
> > a 9v battery, I grounded it to the shell of the sensor
> > applied + to the read lead, grounded the meter (DVM on V),
> > hooked the meter's lead to the white wire, and then tested it.
> > The test being held a gm crank disc near the tip of the toyota
> > sensor.  The meter just flickers as I expose it to the metal?.
> > I thought it would open and close as the metal came close to it?,
> > yes/no?..
> >   In various gm training references they show a pattern like
> >
> >        ___       ___       ___       ___
> > ___I      I___I     I___I      I___I      I
> >
> > Can someone splain this to me, or refer me to an online source for
> > accurate info?.
> > Thanks
> > Bruce
> >
> >
IF it is a HALL, it has no coil. A Hall effect device is solid state and
acts as a switch. Magnet close, one state, magnet gone, other state.
A magnetic reluctance or inductance sensor uses a coil, or two.
All Toyota sensors I have seen are of other than Hall type - but I have
not been around Toys on a daily basis for the last  5 or more years.