Book Analog Interfacing to Embedded Microprocessors
the magnetic field, but it will not be linear with respect to distance.
Geartooth Hall effect sensors include a magnet and Hall effect sensor in
one package. They are designed to measure rotation of a geared device by
placing the sensor near the gear teeth (Figure 3.25). As each gear tooth moves
past the sensor, it affects the magnetic field between the magnet and the Hall
effect sensor, causing an output pulse to be generated.
Clarostat makes a Hall effect potentiometer. This device produces an
output voltage that is proportional to the amount of rotation of the shaft. It
is ideal for applications where a control knob is required, but where the
reliability of a resistive potentiometer is inadequate.
LVDT
The LVDT (linear variable differential transformer) consists of an excitation
coil, two pickup coils, and a movable, magnetic core (Figure 3.26). The core
provides coupling between the coils
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