Hall Effect Transducer
Hall effect transducer serves to measure a magnetic field and convert that measurement into voltage.
If a strip of conducting material carries a current in the presence of transverse magnetic field a difference of potential produce between the opposite edges of the conductor. The magnitude of the voltage depends upon the current and the strength of magnetic field and the property of the conductor, This effect is known as Hall Effect.
The Hall element is constructed from a thin sheet of conductive material with output connections perpendicular to the direction of current flow. When subjected to a magnetic field, it responds with an output voltage directly proportional to the magnetic field strength. The voltage output is very small (μV) and requires additional electronics to achieve useful voltage levels.
Hall effect is present in semiconductor in varying amount depending upon the densities and mobilities of carriers. In the semiconductor field, the Hall effect is most helpful in determining the appropriate doping and polarity of semiconductor materials. The strength of the Hall potential is also proportional to the strength of the magnetic field applied to the metal strip, which is known as a Hall Probe.
Hall effect sensors can be applied in many types of sensing devices. If the quantity to be sensed incorporates or can incorporate a magnetic field, a Hall sensor will perform the task.
By considering the above figure, Current is passed through the leads 1 and 2 of the strip and the output leads are connected to the edges 3 and 4 which are at the same potential when there is no transverse magnetic field passing through the strip.
When the transverse magnetic field passed through the field an output voltage appear across the output leads and this voltages directly proportional to current and magnetic field strength.
- output voltage is given by,
Where, EH = output Hall voltage
KH = Hall effect co-efficient
Where, t = Thickness of strip
I = Current(A)
B = Flux Density In Wb/m²
- Brush-less DC motors.
- Vending machines.
- Proximity detectors.
- Shaft position sensors.
- speed sensor (motor control).
- Valve position Detector.
- Can operate at much higher speeds than mechanical points.
- It can be operated up to 100 kHz.
- It can measure a wide range of magnetic fields.
- Very stable, reliable and long lasting.
- High resolution and small in size.
- The basic sensor has very low output drive capability.
- Difficulty operating in strong external magnetic fields.
- less accurate.
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