Most electromagnetic position transducers are based on transformer technology. Transformers work by exciting the primary winding with a continuously changing voltage and inducing a voltage in the secondary winding by subjecting it to the changing magnetic Ÿeld set up by the primary. œey are ac-only devices, which make all electromagnetically coupled position sensors ac transformer coupled. œey are inductive by nature, consisting of wound coils. By varying the amount of coupling from the primary (excited) winding of a transformer to the secondary (coupled) winding with respect to either linear or rotary displacement, an analog signal can be generated that represents the displacement. œis coupling variation is accomplished by moving either one of the windings or a core element that provides a žux path between the two windings.