Abstract: A transducer for indicating position in space with reference to a coordinate system includes a magnetic field source (13), a movable button element (11) composed of a magnetically susceptible material having a central pole face (16) and a surrounding annular co-planer pole face (19) for providing uniform magnetic flux paths in the annular region between and extending from the plane of the respective pole faces, and a probe element having a plurality of sensor units (41a-d) for electronically measuring magnetic flux through a plurality of separate, geometrically congruent areas arranged around an axis of symmetry (24) in a sensing plane which is spaced from, and parallel to that of the pole faces of the movable button element.