WINKELMESSER

A system for deriving an electrical representation of an angle, which system includes two coils arranged to have their axes perpendicular to one another and connected to receive alternating excitation voltages which are identical except that the voltage to one coil is shifted in phase by 90 DEG relative to the voltage to the other coil, whereby there is produced a magnetic field which rotates in the plane defined by the coil axes, and a positioning member located in the field and mounted for rotation about an axis perpendicular to the coil axes, the angle to be detected being between one of the coil axes and a reference axis fixed relative to the positioning member and extending perpendicular to the axis of rotation thereof. The positioning member includes a high magnetic permeability rod oriented at an angle to the axis of rotation of the positioning member and the system includes a stationary third coil surrounding the positioning member and oriented so that its axis is parallel to the axis of the positioning member. The rotating magnetic field produced by the two coils is distorted by the rod so that a portion of the field flux passes through the region enclosed by the third coil in a direction normal to the plane of the third coil, and induces in the third coil a voltage whose phase relative to the phase of the voltage in one of the two coils corresponds to the angle between the reference axis and the axis of that one coil.