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Hall Sensors


Hall Sensors (also called Hall encoders, accord. to Edwin Hall) uses the Hall effect to measure magnetic fields or electrical currents or positions.

If current flows through a Hall sensor and the sensor is placed in a magnetic field vertical to the current direction, the sensor delivers a voltage that is proportional to the product of magnetic field force and current. If the current value is known, the magnetic field force can be measured. If the magnetic field is produced by an electrical current in a conductor or coil you can do a potential free measurement of the electrical current in the coil.

A Hall sensor also delivers a signal if the magnetic field is constant. This is the decisive advantage compared to the combination of magnet and coil.


  • Magnetic field measuring (magnetic flux density)
  • Potential- free current measurement (current sensor)
  • touch and contact free switches
  • layer thickness measuring

In the car industry Hall sensors are used in the belt lock, in the door closing system, at the pedal state evaluation, in the gear control and in the ignition time measurement. Basic advantage is the insensitiveness against a non- magnetic dirt and water.

You can find them in "real" laser printers - in integrated circuits - to synchronize the mirror position, in disk drives, in brushless motors e.g. in ventilators. There are even keyboards with Hall sensors under every button.

Hall sensors with analog signal outputs are used for measurement of weak magnet fields (earth magnet field), for example with compasses in navigation systems.

They are used as current sensors in the gap of the iron core of a coil. Such current sensors are offered as a complete component, are very fast, can be used for DC measurement, too. They offer a potential separation between power and control circuits.

As position switch or contact free keypad they work combined with permanent magnets and have integrated a threshold switch.


Hall sensors are produced out of thin semiconductor disks, because in these disks the number of electrons is small and therefore the electrons speed is high to reach a high Hall voltage. Typical designs are

  • Rectangle
  • Butterfly
  • Cross

Usually the Hall sensors are integrated to the signal boost circuit or temperature compensation circuit.


The sensitivity is indicated in millivolt per Gauß (mV/G) with
1 Tesla = 10000 Gauß (1 G = 10-4 T).

Rotating Direction, Connection

Rotation clockwise (cw)


Signal Core Color Other Description
H1 (gn) Signal a-b, phase U
H2 (ye) Signal b-c, phase V
H3 (br) Signal c-a, phase W

With 5V power supply via  X1 (S400:X2) observe the Sense line connections (pins 2 to 10 and pins 4 to 12).

Servo Amplifiers with Hall Support

  S300 S400 S601-S620 S640/S670 S700 AKD  
Connector for Hall X1 X2 X1 -> Dongle X1 X1    

Help for setup see page Setup of Hall Feedbacks.