Abstract: An apparatus useful for detecting the speed and/or position of an object moving along a defined path and more particularly to such an apparatus configured to minimize the spacing between a sensing face of the apparatus and a target surface on the object. Embodiments of the invention are particularly suited for sensing the speed of a rotating member, e.g., a gear, by utilizing a sensor, such as a Hall-effect sensor, to detect the movement of each gear tooth past the sensor. An apparatus in accordance with the invention is configured to mount the sensor for adjustable positioning along a sensor path between an initial position and a final operational position. Movement of the sensor along the sensor path is restricted, e.g., by frictional engagement, but can be overcome by contact with the target surface so as to move the sensor to its final position with the spacing, i.e., airgap between the sensing face and the target surface, minimized.

Abstract: A system for converting three-phase AC to DC voltage employs three separate converter circuits having their outputs connected in parallel to reduce current harmonics. Each converter circuit includes a full wave rectifier feeding a pulse width current modulator which modulates the DC current flow to the load in a manner to maintain the magnitude of the DC current proportional to the instantaneous magnitude of the DC voltage. The current modulators act as substantially resistive loads to reduce source current harmonics and correct the power factor. The modulators include a pair of transistors connected in a push-pull circuit which are controlled by an oscillator circuit to modulate the DC current at a frequency which is many orders of magnitude greater than the line frequency of the AC source. The DC current outputs of the modulators are coupled through DC/DC isolation transformers to the load.