a low torque magnetic pick - off assembly has both a stationary magnet and a magnet mounted on a rotating member . the stationary magnet is oriented parallel to the axis of the rotating member and is used to establish a magnetic field in a field guide passing through a coil . the magnet on the rotating member modulates the magnetic field passing through the coil thereby inducing an output voltage in the coil . the output voltages indicates the passage of the magnet on the rotating member past the stationary magnet .