A rotary variable differential transformer produces a substantially linear output over about 180 degrees of rotation of a rotor core. The transformer includes a base housing having a central bore, and a rotor having a shaft whose angular displacement is to be determined and a generally planar, circular rotor core mounted off-center at one end of the shaft and in a plane normal thereto. The rotor core is rotatably disposed within the opening of the base housing. Also included is a primary coil disposed in the opening of the base housing to circumscribe the shaft at a location rearwardly of the rotor core. First and second windings, with cores, are carried by the base housing and positioned about the base housing opening so that the axes of the coils are oriented radially of the opening and generally in a common plane with the rotor core. The first and second windings are connected together in series opposition. A casing surrounds the sides of the base housing and at least a portion of the rear of the base housing, and includes an opening through which the shaft projects.