The
Hall effect sensor is a
magnetic field sensor that
is capable of detecting both
static and
dynamic fields.
Hall effect sensors are made from a
semiconductor
material with a high Hall
constant (like
Indium-
antimony or
indium-
arsenic). There are
several types of sensors available, some have a
linear
output
according to
field strength. Others may have a
output that turns on when the field comes over a
spesific
value. Pure Hall effect elements without built in amplification
also exist.
The Hall effect.
No magnetic field:
_____________________
electron ___/___ /
flow / / ---
-->---/------/--->--- |\ | (no voltage)
/______/ `-o-'
/ /
`------------------/
In a magnetic field(electron flow deflected):
- _____________________
electron ___/___ /
flow / .. / ---
-->---/-' `-/--->--- | /| voltage
/______/ `-o-'difference
/ /
+ `------------------/
The hall effect sensor is
connected to a
DC power supply.
Without a magnetic
flux present the
electrons flow evenly and
straight through the conductor. But when the sensor is
subjected
to a
magnetic field, the field will attract or repel the electrons
according to
polarity(This is due to the electrons charge).
This means that one side of the
plate has a higher
density of
electrons, and this causes an elecrtrical
potential difference
between the sides of the plate. This
potential are almost
propotional
to the strength of the field.
Common places to find these sensors is in
disk drives
and cooling
fans where they are used to
measure rotational
speed. They are also used in DC
amphere meters of the
clamp type.