? on Mr Hall Effect

[Tom Parker]

Gary Derian <gderian at cybergate.net> wrote:

>Hall Effect devices sense the presence of metal, not the transients like a
>magnetic pickup.  Something about electrons flowing in a flat conductor are
>pushed to one side by a magnetic field creating a voltage across the
>conductor.  This cross voltage is amplified to create an output.

This is correct. Some hall effect sensors have a little bit of brains in them
and they can detect metal in the sensing gap in an "on off" fashion. They have
an internal amplifier and transistor switch and when metal goes in, they
switch with a jump.

I've never seen an automotove sensor, nor do I know if they work like this or
just send the hall voltage down the line to the computer. The hall voltage
should rise as the magnetic field rises. How you increase the magnetic field
through the sensor with a piece of (non-magnetic?) steel, I don't know.

--
Tom Parker - tparker at nznet.gen.nz
           - http://www.geocities.com/MotorCity/Track/8381/