Abstract: A circuit which converts one parameter to another such as from temperature to electricity. The circuit comprises a three winding differential transformer with one winding connected to output terminals and each end of the other windings connected to a source (or drain) of a different one of four field effect transistors. The circuit is adapted for receiving an alternating current source to be coupled between drains (or sources) of the transistors connected to one end of each winding and the drains (or sources) of the other transistors. A temperature measuring device and reference temperature measuring device are connected to respective ones of two of the transistors to set the current limits of the transistors as a function of temperature. A voltage produced at the output terminals, when the alternating current source is applied, is proportional to the difference in temperature of the temperature measuring devices.

Abstract: A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.