A device for providing a displacement representative of the magnitude of a signal. The device typically includes a rotor having a plurality of sections of high permeability material separated by areas of high reluctance. A magnetic flux is applied to a section of the rotor to produce an elastic restraint torque varying with angle, while another high permeability section responds to variations in the magnetic flux caused by the signal to produce a torque representative of the signal magnitude. This latter torque moves the rotor to the point where the restraint torque increases sufficiently to balance the signal torque. The resultant angle of rotation represents signal magnitude. The device may also be operated to provide a signal output representative of an input torque or force.