Abstract: Apparatus and method for tuning components of an electrical mechanical filter which includes a plurality of mechanical resonators coupled together with input and output resonators and other resonators mounted between the input and output resonators which can be tuned without mechanically damping the input and output resonators by providing an input feed circuit coupled to the input transducer and an output circuit coupled to the output transducer having characteristics such that the frequency of the resonator without a transducer can be accurately measured and wherein the frequencies of the input and output resonators do not adversely effect the frequency measurement of the resonator without a transducer.

Abstract: The invention is a novel method and apparatus for counting pipe joints, passing through a bell nipple, going downhole and uphole by sensing, at spaced apart positions along the nipple utilizing magnetic fields, for the presence of a joint. Each sensor develops signals as the joint passes it and a logical network determines which direction the pipe joint is traveling, adds a plus count to the joint counter for joints going downhole and subtracts a minus count from the joint counter when a joint is sensed coming uphole. Another logical circuit converts the joint count to a stand count, and the negative signals from the stand count trigger an adder network to introduce a binary number to a numeric read-out display, which number is indicative of pipe displacement per stand, withdrawn from hole.

Abstract: A magnetic locator in which flux-gate sensors are mounted in longitudinal notches at the ends of a tubular support to form an assembly which is inserted into a tubular housing, the sensors being press-fitted into the notches and the tubular support being provided with spaced bushings of material which is compressed when inserted into the housing. A stiff hairpin excitation conductor extends through the sensors and through the tubular support, being preassembled with one of the sensors and being connected to a circuit chassis for positioning the sensor assembly in the housing. A simplified electrical circuit is employed which produces a beat frequency signal when a magnetic object is located and which avoids the need for a voltage to frequency converter.

Abstract: Measuring bridge for a device for inspecting or checking by eddy currents of the type comprising a first pair of adjacent branches each constituted by a resistor and a second pair of adjacent branches in parallel with the first pair, whereof at least one of the branches is constituted by a winding which is sensitive to the faults of the part to be inspected, characterized in that it comprises a supplementary resistor connected in parallel on the said winding.

Abstract: A three axis magnetometer is provided with a single calibration checking l lying in a plane disposed at equal angles to each of the three orthogonal axes of sensitivity. Energization of the calibration checking coil with a known current while the calibrated magnetometer is in a known condition of calibration provides sensitivity readings for each of the three axes, which readings provide a standard of comparison for checking the calibration and sensitivity of the magnetometer by similar energization of the coil when the magnetometer is disposed in a remote operational environment.

Abstract: A stator lamination compression mechanism simultaneously monitors the axial length of a series of laminations to be used in an electric motor. A linear variable differential transformer provides a movable coupling element connected to a sensing member monitoring the axial length of the compressed laminations. A specially designed sensing circuit responds to variations in magnitude and phase of a single ended output signal provided by the differential transformer and continuously tracks the movement of the coupling element. The monitor provides warnings when the axial length varies beyond predetermined selected magnitudes.

Abstract: A caliper gauge for measuring the thickness of a sheet has a transmitter generating a magnetic field on one side of the sheet and a receiver detecting the amplitude of the magnetic field on the other side of the sheet. Both the transmitter and receiver are maintained at a constant distance from the sheet. The transmitter comprises an electrical wire wound a plurality of times about a cylindrically shaped body of a magnetically susceptible material. The receiver also comprises a cylindrically shaped body with an electrical wire wound a plurality of times about it. The transmitter is positioned such that the axis of the cylindrical body is substantially perpendicular to the sheet. The receiver is positioned such that the axis of the cylindrical body is substantially aligned with the axis of the transmitter.

Abstract: A magnetometer wherein inductance of a resonant circuit is made sensitive changes in magnetic field to vary an oscillator operating frequency. The magnetometer utilizes a ferromagnetic sensor element that is characterized by high permeability in weak magnetic fields when the element is maintained at predetermined elevated temperatures near the Curie point of the element material and also exhibits a hysteresis curve having a steep slope in the region of field strengths on the order of the earth's magnetic field. The preferred embodiment includes resistive heating of the element and use of substantially pure iron as the element material.

Abstract: Apparatus monitors the wear of a propeller shaft bearing such as may be found in a tanker, or any other ship, while it is in service. As the shaft is rotating a sensor provides a signal corresponding to the displacement of the shaft with respect to its longitudinal axis. The displacement signal is applied to an averaging network which provides a signal corresponding to the average displacement to a recorder. The recording of the average displacement signal permits determination of wear of the shaft bearing.

Abstract: A position indicating device for providing a generally linear output in response to displacement; the system includes a Hall effect device and apparatus for providing a response therein in accordance to displacement of a movable stylus or plunger and the method of making the same.

Abstract: The invention relates to a method and apparatus for the non-destructive testing of pipelines and is particularly concerned with the use of alternating eddy currents to investigate anomalies in the walls of pipelines of ferromagnetic material. A probe includes sensing coils which are connected in a bridge circuit. By employing spiral coils, placed with their axes normal to the surface of the pipeline wall, the apparatus is made less sensitive to variations in the spacing of the probe and sample. Use of biassing magnetic fields permits the detection of anomalies in pipeline walls of thickness substantially greater than the normal eddy current penetration depth.

Abstract: A device for detecting phase transformations in a magnet material is disclosed. A sample is placed in a coil coupled to a harmonic oscillator and subjected to heat radiation means for simulating predetermined heating and cooling rates which result in phase transformations within the material being tested. The phase transformations are a function of changes in magnetic permeability which vary with temperature changes.

Abstract: A pipeline inspection vehicle for detecting defects in the pipeline wall provided with a detector support system comprising a freely supported ring encircling the body of the vehicle and on which are mounted a plurality of spring-loaded pivotally connected link plates, the outermost plates of which carry flux-sensing devices and are urged by spring means resiliently to engage the inner surface of the pipeline wall.

Abstract: An element together with a prospective shunt load is magnetized to become a permanent magnet whereafter the magnet is stepwise demagnetized, actually along the demagnetization curve but due to load along a load line passing through a point inside the demagnetization curve independently from any variations thereof. This point will serve as operating point of the magnet in the system and the load line is characterized by identifying the operating point establishing a minimum induction on the basis of the shunt so that during normal operation of the magnet in a system smaller flux will not be extracted. The demagnetization steps are tracked by interspersed measuring steps to monitor approach of the desired operating point. The system is preferable a relay and magnetization, demagnetization, measurement and termination are carried out in a different, closed loop system.

Abstract: Installation for the measuring of an essentially linear displacement of a body, with a fixed coil and axial direction of which corresponds to the direction of the displacement to be measured, a rod the magnetic permeability of which differs from the magnetic permeability of the medium which is surrounded by the coil, means for connecting said rod along the axis of the coil to that body the displacement of which should be measured, an A.C. source with constant amplitude and pulsation (angular frequency) causing a voltage drop in the coil, means electrically connected to the coil and generating a voltage signal dependent of and in phase with the voltage drop in the coil, means electrically connected in series with the AC current source, generating a signal proportional to and in phase with the current through the coil, means for phase shifting by 90.degree.

Abstract: A flaw detection device, and method of operation thereof, for inspecting an entire workpiece, such as a tube or pipe, for the presence of defects. The detection device includes a plurality of pickup arms mounted in spaced relation with respect to each other around a work path, and a plurality of sensing coils carried by each of the pickup arms. The pickup arms are each mounted on a support member to pivot on an axis transverse to the direction of the work path so that the sensing coils may be moved into proximity and around the circumference of a workpiece as the workpiece travels along the work path.

Abstract: A ferrous metal detecting apparatus is disclosed for detecting metal particles in a flowing fluid, such as engine oil. The detecting apparatus has soft-iron pole pieces with a bridging gap therebetween. The soft-iron pole pieces are electrically insulated from each other and magnetized by direct current through an electromagnetic coil. After a sufficient amount of ferrous metal has accumulated on the bridging gap, a level detector will give a warning signal and cause the electromagnetic coil to degauss the soft-iron pole pieces by applying an alternating current to the electromagnetic coil. After the flowing fluid has washed away the ferrous metal, the direct current will remagnetize the soft-iron pole pieces. If repeated warning signals are within predetermined time intervals, an indication of the amount of ferrous metal contained in the fluid can be interpolated. The recycling for repeated warning signals may be automatically provided through a timing circuit and control logic.

Abstract: The elongated core of a magnetic field probe is constructed of a heat-resistant diamagnetic body with lengthwise openings into which are received closely fitting wires of a magnetizable material. The wires are secured to the body by a heat-resistant cement. An excitation winding wound onto the core extends substantially beyond the core wire ends and a receiver winding is slidably received on the core.

Abstract: A system for indicating the sweep rate of an oscilloscope time base. A counter is enabled by a sweep gate signal to permit clock pulses having a predetermined repetition rate to be counted during the time a sweep-driving ramp waveform is generated. The count output, which is proportional to the length of a time-base sweep, is decoded to generate specific control signals indicative of the sweep rate thereof. The control signals may then be used by a utilization means to provide a visual readout of the time-base sweep rate or to provide auto ranging for a digital voltmeter scaled in time units for time interval measurements.

Abstract: A thin film magnetoresistive sensor of NiFeCo is juxtaposed with a saturable thin film shield of more highly permeable NiFe material. The curve depicting change of resistance of the sensor as a function of applied magnetic field is flattened, permitting the sensor to provide a magnetic switch, such as a keyboard transducer, a sensor of current through wires, a magnetic bubble detector and a remote control scanning sensor in a recording head. The scanner involves a stepped arrangement for providing different levels of sensitivity for adjacent sections of the magnetoresistive sensor.