Abstract: Detector comprising two windings (1,2) disposed in two ferrite half-pots (3,4) opposite to two non-ferromagnetic metallic elements (5,6) one at least of which is movable. A pulse generator (9) feeds the two windings through resistances (7,8) coupled to a reference potential.Two circuits (10,11) detect the peak values of the resultant signals at the common points between the windings and their charging resistance. An operational amplifier (12) creates the difference of these peak values. A diode (13) permits the discharge of the windings through the resistances (7,8).Application to detectors of differential pressure, and to devices for the measurement of displacements.

Abstract: A device for converting a pneumatic or hydraulic pressure into an electrical current and vice versa according to the compensation principle, with a pressure transducer with a pressure-dependent moveable element, an electromagnetic force transducer, the moveable part of which force transducer standing in connection with the element, and a position indicator transmitter which converts the movement of the pressure transducer into an electrical or pneumatic control signal for the force- or pressure transducer. As a pressure transducer, there are provided two bellows with slightly different operative or effective surfaces which respectively are each fixed on one end and with their other ends stand in connection with one another and with the moveable element and are subjected to the same pressure.

Abstract: A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates on one side with the internal pressure to be measured and on the other side with an external pressure which is applied by an external pressurizer-control system and which is communicated to the sensor through the intact skin. An imbalance of the two opposing pressures causes a displacement of the movable element which changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit. This change is detected outside the body by an external detection system, such as a frequency swept radio frequency oscillator. The external pressure is varied until the external detector senses that the pressures are balanced on the movable element, at which point the external pressure equals the internal pressure, and the former is measured and read out.

Abstract: A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates with the internal pressure of the body to be measured on one side and the atmospheric pressure on the other, the latter communicated through the intact skin and a nearly coplanar membrane. The movable element's differential pressure dependent displacement changes a physical characteristic of the sensor, such as the resonant frequency of a tune L-C circuit, and the change is detected external to the body by a radiating detector system, such as a frequency swept radio frequency oscillator, by which the internal pressure is read out.

Abstract: A balance beam has a fulcrum, at least one bellows (connected to a source of pressure or vacuum) acting on the beam and a connection to the armature of a differential transformer at one end. A poise is mounted for movement along the beam by rollers riding on shoulders formed on the beam. A carriage having a connection to the poise at the elevation of the axes of the rollers moves the poise and is, in turn, driven by a screw turned by a servomotor controlled by the differential transformer. Provision is made for minimizing temperature error both longitudinally and transversely of the beam. The fulcrum and bellows may be moved to different locations relative to the beam, using spaced drilled holes in the beam and the base plate. Various readouts may be connected to the screw, and recorders and control devices may also be driven by the screw.

Abstract: A balance beam has a fulcrum, at least one bellows (connected to the source of pressure or vacuum) acting on the beam at a point along its length and a connection to the armature of a differential transformer at one end. A poise is mounted for movement along the beam by rollers riding on shoulders formed on the beam in a unique arrangement. A carriage having a connection to the poise at the elevation of the axes of the rollers moves the poise and is, in turn, driven by an expansible belt, chain or cable extending around two sprockets, one of which is driven by a servo-motor controlled by a circuit including the differential transformer. Careful provision is made for temperature compensation both longitudinally and transversely of the beam yet the drive elements are elastic. The bellows may be moved to different locations relative to the beam by use of pre-drilled holes in the beam and base plate. Two bellows, on opposite sides of the fulcrum, may be used to gauge pressure differences.

Abstract: A differential pressure transducer, primarily for measuring gauge pressure, comprises first and second identical, substantially cylindrical, sealed capsule assemblies, each having a circular diaphragm at one axial end. The capsule assemblies are welded into the opposite ends of a cylindrical housing, with the diaphragms facing outwardly. The housing is designed to permit the transducer to be mounted in the wall of a pipe or chamber, with the diaphragm of one capsule subjected to the fluid pressure in the pipe or chamber and the diaphragm of the other capsule subjected to ambient atmospheric pressure. Respective inductive displacement sensors produce respective signals indicative of diaphragm displacement. The use of sealed capsules ensures that if a diaphragm ruptures, fluid loss cannot occur.

Abstract: To measure small displacements, for example displacement of a membrane under change of pneumatic pressure applied at opposite sides thereto, a ferromagnetic wire is stretched between a fixed support and the membrane. An exciter coil, connected to a source of alternating current of suitable strength cyclically reversely magnetizes the ferromagnetic wire. A pick-up coil is electromagnetically coupled to the wire to sense the change of magnetization thereof which will be in the form of sharp needle pulses as the magnetization of the wire changes, the pulse amplitude and pulse width being highly dependent on the strain in the wire and hence on the deflection of the membrane. The wire may be stressed under tension.

Abstract: A differential pressure sensing device is fully implanted in the body of a patient to monitor internal pressure such as intracranial pressure. A movable element in the sensor communicates on one side with the internal pressure to be measured and on the other side with an external pressure which is applied by an external pressurizer-control system and which is communicated to the sensor through the intact skin. An imbalance of the two opposing pressures causes a displacement of the movable element which changes a physical characteristic of the sensor, such as the resonant frequency of a tuned L-C circuit. This change is detected outside the body by an external detection system, such as a frequency swept radio frequency oscillator. The external pressure is varied until the external detector senses that the pressures are balanced on the movable element, at which point the external pressure equals the internal pressure, and the former is measured and read out.

Abstract: Pressure ratio transducer system in which input pressures are converted to electrical signals and the electrical signals are processed to produce an output signal corresponding to the ratio of the input pressures. The system is particularly suitable for use in an aircraft for determining the ratio of the change in pressure due to motion of the aircraft to the static pressure in the air surrounding the aircraft.

Abstract: A mechanical and electrical pressure sensor wherein the mechanical part includes a fluid pressure chamber with a magnetic, electrically conductive diaphragm moving out-of-contact with a stationary contact in the presence of pressure and into contact therewith in the absence of pressure or because of energizing of a cooperatively acting magnetic coil. The electrical circuit connected to the coil includes a clocked flip-flop, the output of which is high during a time interval when the contacts are open (coil energized) and which is low when the contacts are closed (coil deenergized). The duty cycle of energized time to total time is a measure of average coil winding current, and, hence, sensed pressure. The ratio of energized intervals to total intervals develops a useful digital measurement of pressure readily useful in a computer.

Abstract: A three bellows transducer having two absolute bellows of equivalent configuration that isolate the motion detecting coils from the pressure media and respond only to change in line pressure to provide a zero shift and a large differential bellows that responds to a pressure differential to provide an electrical output which is a function of such pressure differential.

Abstract: A magnetostrictive pressure transducer is disclosed wherein pressure in the range of zero to 1000 psi can be accurately measured. The pressure transducer apparatus includes a diaphragm causing the pressure to be applied unidirectionally on sensor material having the property of undergoing changes in magnetic induction when a pressure is applied thereto, the change in magnetic induction being related to the applied pressure. The change in magnetic induction is measured and thus provides a measurement of the applied pressure. Several embodiments are also disclosed for measuring vacuum. In these embodiments force is also applied unidirectionally on the sensor material.

Abstract: A pressure measuring system which includes a variable reluctance pressure transducer energized from an alternating voltage source, wherein the ratio of the output voltage to the source voltage is proportional to the pressure being sensed. Precision full wave rectifiers convert the source and output voltages to reference and sensing direct voltage signals, respectively. A switching regulator regulates the higher amplitude reference voltage signal to have exactly the same average voltage as the sensing voltage signal. The switching regulator also regulates a constant voltage DC signal from a regulated power supply at the same switching duty cycle as the regulated reference voltage signal, to produce a direct voltage, pressure-sensing signal which is uneffected by voltage fluctuations in the alternating voltage source for the pressure transducer.

Abstract: A pressure transducer comprises a series-connected helical coil spring and bellows assembled into the bore of a housing by anchoring the spring and bellows at locations which place them in a state of tension. Expansion and contraction of the bellows reacts against the spring and correspondingly positions a ferrite slug within an inductance coil to cause the inductance thereof to be a function of the pressure differential acting on the bellows. One end of the coil spring is threaded onto a threaded fitting secured to one end of the bellows, and slope calibration of the transducer is accomplished by setting the amount of engagement of the spring with the threaded fitting. Offset calibration can be performed by either of two disclosed techniques, and the offset and slope calibrations can be independently made.

Abstract: A pressure indicator of the kind comprising a diaphragm box containing two chambers which are completely separated by a resilient diaphragm, each of the chambers communicating via a connecting channel with an associated one of two fluid sources between which a pressure difference is to be established. A metal plate is fastened to the diaphragm, and an inductive sensor is disposed at one of the walls of the diaphragm box, so that a pressure change in at least one of the chambers causes a change in distance between the metal plate and the sensor and, consequently, an output signal from the sensor.

Abstract: Servo pressure pickup comprising a sealed housing having a pressure inlet and in which is mounted an anaroid capsule one wall of which is mechanically linked to an electrical displacement measuring device. The current feed of an electromagnet is controlled by the measuring device. The electromagnet includes a movable core interposed between the capsule and the displacement measuring device. The electromagnet is designed to generate a force in opposition to that produced by the expansion of the capsule and proportional to the feed current of the electromagnet from the measuring device. The displacement measuring device may be amplified and used to generate an analog or a digital pressure measurement output signal.

Abstract: A magnetostrictive pressure transducer is disclosed wherein pressure in the range of zero to 1000 psi can be accurately measured. The pressure transducer apparatus includes a diaphragm causing the pressure to be applied unidirectionally on sensor material having the property of undergoing changes in magnetic induction when a pressure is applied thereto, the change in magnetic induction being related to the applied pressure. The change in magnetic induction is measured and thus provides a measurement of the applied pressure. Several embodiments are also disclosed for measuring vacuum. In these embodiments force is also applied unidirectionally on the sensor material.