Direct Energy, 2018a

5 HALL EFFECT 99
Hall effect device
motor
Figure 5.2: Placement of Hall eect sensor used as a tachometer.
sensors are found in devices ranging from water softeners to ocean current
monitors [57]. To detect owrate, a blade is mounted so that it rotates
in the water ow. Magnets are mounted on the blade, and the Hall eect
sensor is mounted nearby. When the blade passes the sensor, the magnetic
eld at the sensor changes and induces a voltage in the Hall eect sensor.
Following the same principle, Hall eect sensors are used to measure the
speed of paper owin copiers, needles in sewing machines, drill bits in
drilling machines, and bottles in bottling factories [57].
Multiple types of Hall eect devices are used in cars. Hall eect sensors
are used as rotation sensors to detect transmission speed [57]. They are
used as proximity sensors to detect the shift lever position, crank shaft
position, and throttle position [57]. They are also used in door interlocks,
in brake skidding detection, and in traction control systems [57].