EVKT-KNOB – ROTARY KNOB KIT FOR THE MAGALPHA
MAGNETIC FIELD
An NdFeB cylinder magnet is mounted at the end of the aluminum shaft.
Table 4: Magnet Characteristics
Material
Remanence (Br)
Diameter
NdFeB (N35 or N35H)
1.2T
5mm
Height
2.5mm
Magnetization
Diametrical
How to Change the Mechanical Zero
Unscrew the knob with a 1/16-inch hex key (Allen wrench). Hold the shaft with a pin inserted in the 2mm
diameter hole, and rotate the knob to the desired position. When tightening the screw, ensure that the
key is fully inserted. Note that the zero position can also be adjusted through programming, as described
in the MagAlpha datasheet.
Figure 7: Adjusting the Magnet Angular Position
How to Change the Magnetic Field Amplitude
The performance of the MagAlpha remains the same from 75mT to 150mT and higher (the MagAlpha
has no maximum operating field). The critical region is the lower end of the specified range. Some
parameters (e.g. noise, linearity) deteriorate gradually when the magnetic field becomes weak. The two
spacers enclosed in this evaluation kit allow the sensor (the noise level in particular) to be tested at low
magnetic fields.
Figure 8: Magnetic Field vs. Air Gap for the Supplied Magnet
EVKT-KNOB Rev. 1.0
4/2/2019
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