Abstract: A signal isolator has an acoustic transmitting medium with a first pair of acoustic transducers thereon for transmitting an input signal through the medium at a first frequency. A first transmitting and receiving circuit is used in combination with the first pair of transducers. A second pair of transducers is located on the acoustic medium to transmit a power supply signal through the medium at a second frequency. Power supply means associated with the power supply signals are used to energize the transmitting and receiving means on opposite sides of the medium.

Abstract: A distance measuring apparatus and a differential pressure transmitter utilizing the same having an ultrasonic element reflector mounted between a pair of ultrasonic transducers. The alternate operation of the ultrasonic transducers produces a pair of transducer energizing signals which are related to the relative separation of the reflector element from the transducers. In one embodiment, the reflector element is mounted within a closed pressure vessel divided internally by an ultrasonic reflector diaphragm with a pair of fluid inlet lines admitting respective pressurized fluids to corresponding sides of the reflector diaphragm.

Abstract: In a differential pressure to electric current transducer, a short sapphire slab carries a strain sensitive resistive pattern. The sapphire slab is an element of a much larger beam as the beam moves to change the stress of the other surfaces of the sapphire slab and varies the resistance of the silicon resistive pattern to produce an electric current signal indicative of the differential pressure.

Abstract: A differential pressure to electrical signal transmitter has a pair of flat barrier diaphragms and a central control diaphragm located between the barrier diaphragms. First chambers between one of the barrier diaphragms and the control diaphragm, and a first length of capillary tubing connected between the first chambers and one chamber of a remotely located sensor capsule, are filled with a first incompressible fill liquid. Second chambers between the other barrier diaphragm and the control diaphragm, and a second length of capillary tubing connected between the second chambers and another chamber of the sensor capsule, are filled with a second incompressible fill liquid. The fill liquids are made to pump up their respective flat barrier diaphragms to cause the latter to have a dome shape and hence to be free from "oil canning." A chamber on the outside of one barrier diaphragm is pressurized with a first fluid, and a chamber on the outside of the other barrier diaphragm is pressurized with a second fluid.

Abstract: A closed system couples the inlet and outlet pressures generated by a centrifugal pump to a pair of flexible diaphragms which seal the flow tube in a pressure rebalance system for measuring fluid flow. The system is filled with a conducting fluid which forms certain resistance paths whose resistance varies with diaphragm position. This resistance change is used to generate signals which control the pump motor to the end that the diaphragms maintain a predetermined position and the pump head is equal to the differential pressure.

Abstract: A closed system couples the inlet and outlet pressures generated by a centrifugal pump to a pair of flexible diaphragms which seal the flow tube in a pressure rebalance system for measuring fluid flow. The system is filled with a conducting fluid which forms certain resistance paths whose resistance varies with diaphragm position. This resistance change is used to generate signals which control the pump motor to the end that the diaphragms maintain a predetermined position and the pump head is equal to the differential pressure.