hall effect transducers

1. HALL EFFECT
TRANSDUCERS

2. TRANSDUCERS
It converts one form of
energy into another form of
energy, either for
measurement or for control.
If it is for measurement, then
And if for
it is called as Input
control, then, Actuator.
transducer or sensor.

3. Passive Active
Transducers. TYPES
Transducers.

4. Those which
provide
Active electrical signals
Transducers in the form of
voltage &
current.

5. It belongs to one HALL EFFECT
of the TRANSDUCERS
Galvanomagnetic
phenomena.
It was discovered in
1879.

6. CONTD.
In which interaction
between magnetic field &
moving electrical charges
results in the development
of forces that alter the
motion of the charge.
The Hall effect is observed
in all metals, but it is
prominent in
semiconductor materials.

7. CONTD.
A thin strip of bismuth
or n-type germanium is
subjected to magnetic
field B normal to its
surface, while it carries
a current along the
length of the strip, but
normal to B.

8. CONTD.
The magnetic field exerts a
The edge surfaces act like charged
force(known as Lorentz force) on
electrodes and the potential
the electrons moving at a velocity
difference measured b/w P & Q is
v, with the result that some of
known as Hall potential Eh, which
them drift towards the edges of
increases with increase of B & I.
the strip.

9. CONTD.
The build up of the
charge on the edge
surfaces will, in
turn, develop an electric
field(Hall field) of such a
polarity that counteracts
the collection of charges
on the surfaces.
The force on the
electrons due to Hall
field & Lorentz force
balance each other
finally.

10. CONTD.
If e is the charge of
The time required
the electron, then
to reach this
the Lorentz force
equilibrium is about
Bev & the force due
10 to the power -14
to Hall field are
s.
equal to each other.

11. • Hence, Bev = e /b
)
• Or, = Bbv(volts)
• If mobility of the charge carriers is represented by
χ, then v is given by
• V= χ /L
• The Hall coefficient depends on the no. of free
charge carriers per unit volume.
• = ( )/(n )
n

12. APPLICATIONS
It is preferred for
mapping of
The Hall effect
magnetic field With & wihtout
transducer is
around conductors the presence of
primarily suited for
carrying large metallic objects in
the measurement
currents under their vicinity.
of magnetic fields.
different flow
conditions,

13. CONTD. This transducer has made it
possible to measure dc & ac
currents in conductors without
interruption of the circuit and
without making any electrical
contact with the conductor.
The range of current that can be
measured in this manner can be
as low as 0-1 mA or as high as 0-1
kA.

14. CONTD.
It is used as a Proximity
In Instrumentation, the Hall
detector, and also to
element is highly valued for
measure the change in the
its speed of response in The advantages are its
strength or direction of the
detection of changes in the small size & high sensitivity.
magnetic field due to
magnetic field to which it is
displacement or nearness
exposed.
of the test object.

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