Hall-IC

Hall-IC

DC motor application of Hall-effect
A permanently fixed multi-pole ring magnet on the armature shaft can interact with a Hall sensor IC. The resulting output voltage pulses from the Hall circuit, when passing from pole-to-pole of the ring magnet, can be counted to determine the number of revolutions for a given time period and thus the rotation speed of the motor. Where the final actuation function is a linear displacement the velocity can also be calculated where necessary.
Using two adjacent Hall-ICs installed at an angle θ in the motor allows the sense of rotation to be determined also.