Abstract: A method of assembling an inductive proximity sensor maintains inductive coil wound bobbins in fixed relation to an inductive core within a housing. The method includes configuring two inductive coil wound bobbins with an integral ledge cantilevered from an inside surface thereof for forming a pocket under the integral ledge at a bottom of each bobbin; disposing each inductive coil wound bobbin around a corresponding leg of the inductive core; containing a foot of each core leg into the pocket of the corresponding bobbin; inserting each of two legs of a thruster element into a corresponding bobbin so that each leg rests upon the ledge of the corresponding bobbin; disposing the inductive core, inductive coil wound bobbins, and thruster element into the housing; disposing a spring element on a top surface of the thruster element; and compressing the spring element against the top surface of the thruster element.

Abstract: A method of non-intrusive, inductive proximity sensing of a target through a conductive barrier comprises the steps of: disposing an inductive proximity sensor on one side of a barrier of conductive material; disposing a target on the other side of the barrier; determining an appropriate drive frequency for operating the proximity sensor based on the conductive material and thickness of the barrier; and operating the proximity sensor with the appropriate drive frequency to non-intrusively sense the proximity of the target through the conductive barrier.

Abstract: A liquid sensing apparatus for a fuel tank comprises a first optical sensor for producing an output having a first state that corresponds to the first optical sensor being exposed to air and a second state that corresponds to the first optical sensor being exposed to fuel; and a circuit for detecting the first and second optical sensor output states. The sensor circuit also has self test capability for testing both active and passive components. The sensor circuits can be accessed using a two wire only interface, and thermal stability can be achieved with the electronic circuit as shown.

Abstract: An optical point level sensor for fluids includes a prism exposable to a fluid such that electromagnetic energy is reflected internally the prism dependent on the fluid level; and a lens optically connectable to an electromagnetic energy source and an electromagnetic energy detector such that electromagnetic energy from the source enters the lens at a first location axisymmetric to a second location where electromagnetic energy exits the lens to the detector. In one embodiment the lens is a GRIN lens.