H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
H01F21/00—Variable inductances or transformers of the signal type
H01F21/02—Variable inductances or transformers of the signal type continuously variable, e.g. variometers
H01F21/06—Variable inductances or transformers of the signal type continuously variable, e.g. variometers by movement of core or part of core relative to the windings as a whole
H01F21/065—Measures for obtaining a desired relation between the position of the core and the inductance