Abstract: An inductive joystick includes a movable actuator which carries an element of electrically conductive low magnetic permeability material (e.g., copper or aluminum), such that movement of the actuator differentially affects the coupling between a primary coil and a pair of secondary coils which are encircled by the primary coil. The arrangement provides a desirable output characteristic, in which the minimum output of each secondary coil is preferably greater than the maximum difference between the outputs of the two secondary coils, useful for detecting component failure. The secondary coils are preferably connected in a processing circuit which rectifies the outputs of the two coils before combining them to form a resultant "difference" output.

Abstract: A linear displacement transducer comprises a winding, a magnetic core which is linearly displaceable relatively to the winding, and a source for energizing the winding with a constant RMS alternating current at a frequency sufficiently high for the resistive losses in the magnetic core to cause the voltage across the winding to vary substantially linearly relative to the linear displacement of the magnetic core. The frequency may, for example, be in the range 10 to 20 kHz, and a temperature sensing winding may be associated with the winding to enable the output from the transducer to be compensated for temperature changes, or the winding may be used in time-division multiplex for this purpose.