Abstract: A magnetically variable differential transformer, comprising: a primary winding; a first secondary winding; a second secondary winding; a non-movable permeable core disposed within the primary winding, the first secondary winding and the second secondary winding; and a movable magnet configured for movement about the primary winding, the first secondary winding and the second secondary winding, wherein movement of the movable magnet causes magnetic saturation of portions of the non-movable permeable core.

Abstract: A method and apparatus for detecting the concentration of soot particles in engine oil. A microwave signal having a varying frequency is applied to a transmission line having a probe tip exposed to the engine oil. A voltage is read at a stationary detection point along the length of the transmission line for each applied frequency. The applied frequency when the probe voltage is equal to a null voltage of a standing wave within the transmission line is compared to a reference frequency determined when the probe voltage is equal to a null voltage for a known concentration of soot particles. The concentration is calculated based upon the result of the comparison. Preferably, a reference probe receives the same input signal. A known relationship between the reference probe and the transmission line is then used to eliminate temperature effects on the applied frequency.

Abstract: A modular interconnecting component support unit has a rigid plate (14) with a planar face (16) and a rib (24) and a slot (38) extending parallel the plate face but from opposite sides or edges (22, 34) of the plate so that two such units may be slid together while their faces are in planar relationship. Locking arms (46) adjacent the ends (40) of the slots (38) are provided to releasably grip a rib (24) of one unit received in the slot (38) of a second unit. A medical device, such as a reusable portion of a medical pressure transducer (20), may be permanently affixed to the plate face (16).