An apparatus for providing a signal related to a position of a part comprises an exciter coil, and a receiver coil disposed proximate to the exciter coil. The exciter coil generates magnetic flux when the exciter coil is energized by a source of electrical energy, such as an alternating current source....http://www.google.de/patents/US7821256?utm_source=gb-gplus-sharePatent US7821256 - Linear and rotational inductive position sensor
