Abstract: A magnetic detector, such as is used in a frequency generator, for detecting the rotational rate of a motor includes magnetic resistance elements and an operational amplifier. The magnetic resistance elements have a predetermined resistance ratio and are connected serially between a power source and ground. The common node between the two magnetic resistance elements serves as an output terminal for providing an output voltage. The output voltage from the output terminal being supplied to one of the two input terminals of the amplifier. The voltage from a resistance voltage divider disposed between the power source and ground is supplied to the other input terminal of the amplifier. A change of the resistance ratio between the two magnetic resistance elements is effected by a resistor disposed in series with the elements or in parallel with one of the elements.

Abstract: A magnetic inspection head adapted for use with samples having non-planar surfaces. A magnetically permeable core has a pair of poles joined by a magnetically permeable bridge to form a closed magnetic circuit between the pole legs, bridge and the test material. Each pole has magnetically permeable support means terminating in a magnetically permeable deformable surface for engaging the sample. The support means is yieldable such that when the inspection head is placed in contact with the irregular surface of the sample, the deformable surface is deformed to accommodate the shape of the sample with minimal air gaps therebetween. Preferably, the deformable surface is provided by a plurality of pins slidably engaged in a pole structure and urged outwardly for contact with and conformance with a non-planar sample surface.

Abstract: An agricultural harvesting machine having feed rolls for feeding crop material along a feed path to a cutterhead which chops the crop material is provided with a metal detector for detecting ferrous metal objects passing along the feed path. The metal detector comprises a plurality of magnets and a plurality of generally planar Hall effect sensing elements. The magnets collectively produce a detection field which extends into the crop feed path. Each sensing element is disposed such that the magnetic field produced by two adjacent magnets is normal to the plane of the sensing element. In addition the sensing elements are disposed in a plurality of planes all normal to the crop feed path. However, the sensing elements are disposed in planes oriented at different angles relative to the direction of crop feed.

Abstract: A testing method and apparatus detects magnetic discontinuities in a sample of magnetizable material. The apparatus may include an electric motor, a transmission, driven transport wheels, and non-driven transport wheels. Further, the apparatus includes a magnetizing device for inducing a magnetic field in the sample. A sensor unit detects magnetic stray flux from the magnetic field induced in the sample and converts the detected magnetic stray flux into a signal for processing by a signal processor.

Abstract: An apparatus to detect damage in the metallic magnetically permeable reinforcing cables in a conveyor belt. The apparatus includes a field coil to generate a magnetic field passing through the cables, and Hall effect sensors to detect change in reluctance in the field adjacent to the conveyor belt. The conveyor belt is moved relative to the apparatus so that when there is a damaged area, this will change the reluctance path, which changes the field intensity and is in turn detected by the Hall effect sensors.

Abstract: A detection system for detecting and/or verifying the magnetic properties of the magnetic ink layer on common printed or copied documents includes, in order of interaction with the magnetic ink of a Document, a saturation record head, a saturation read head, a non-saturation record head, and a non-saturation read head. The disclosed method of operation is equivalent to the normal testing of the magnetic layer of a Document, but eliminates the need for an erase magnet.

Abstract: A method and apparatus for electrically exciting a magneto-resistor (MR) device that is adapted to sense variations in a magnetic field. Electric current is delivered to flow through the MR device and produce a voltage drop across the resistance the MR device, where the voltage drop varies in accordance with changes in the flux density of the sensed magnetic field. The current flowing through the MR device is limited to a predetermined maximum current value to prevent damage to the MR device due to self heating at elevated operating temperatures. When the delivered current is less than the predetermined maximum current value, the current flowing through the MR device is controlled to maintain a measured characteristic of the voltage drop appearing across the MR device at a desired value. This increases the sensitivity of the MR device over its operating temperature range to variations in the sensed magnetic field.

Abstract: A magnetoresistor (MR) and a non-magnetoresistor (NMR) are formed of indium antimonide or other magnetoresistive material in thermal proximity to each other on an integrated circuit substrate (100). Hall effect shorting strips (104) are formed on the magnetoresistor (MR) to make it much more magnetoresistive than the non-magnetoresistor (NMR). A current mirror (80) causes equal constant currents (I2) which do not vary with temperature to flow through the magnetoresistor (MR) and non-magnetoresistor (NMR), such that magnetoresistor and non-magnetoresistor voltages are developed thereacross respectively. The magnetoresistor and non-magnetoresistor voltages vary equally in accordance with temperature. The magnetoresistor voltage also varies in accordance with applied magnetic flux. A comparator (66) subtracts the non-magnetoresistor voltage from the magnetoresistor voltage to produce an output signal (Vout) with the temperature variation canceled, and which thereby varies only in accordance with magnetic flux.

Abstract: An eddy current probe for detection of cracks in multi-layered structures. The probe includes a body of a material having high permeability and is shaped to include a central core and an additional wall. A central core drive coil is wound around the central core of the body and a plurality of sense coils are located in an array in association with the additional wall. An outer drive coil is wound about the outside of the additional wall. The central core drive coil is excited with a first alternating current high frequency signal producing eddy currents primarily in the top of the layered structure. These eddy currents are sensed with the sense coil array and analyzed for structural defects in the top surface of the layered structure. The central core coil is excited with a second alternating current signal of a lower frequency than the first signal producing eddy currents in deeper layers of the structure. Such eddy currents are sensed by the sense coils and the signals so sensed are stored.

Abstract: A motion transducer for measuring the displacement of, for example, shafts in gas control modules. The shaft 14 carries two magnets 10, 12 each of hollow cylindrical form, the magnet 10 presenting a south pole everywhere over its external cylindrical face and the magnet 12 presenting a north pole everywhere over its external cylindrical face. The shaft 14 moves vertically past an array of Hall-effect sensors 18-24 to produce sinusoidal voltage outputs at the sensors. The outputs are combined in a summing amplifier (FIG. 3). The combined output is not affected by rotation of the shaft and magnets nor by tilting or sideways displacement of the axis 16 of the shaft. That is because no matter what the rotational position is the sensors are always subjected to the same magnetic field and, if the shaft tilts or is displaced sideways an increased field at some sensors is compensated by a decreased field at others.(FIG. 1 is suggested as the accompanying drawing).

Abstract: The operational fitness of a magnetic sensor for detecting buried magnets can be tested from time to time by an electromagnet installed in proximity to the sensor. The electromagnet is a small coil of wire mounted near the sensor, such as a Hall effect device, which when energized, generates a test magnetic field. The analog output of the sensor is compared with preestablished values when the electromagnet is energized to verify the proper operation of the sensor; it is also compared with preestablished values when sensing buried magnets to confirm operation of the sensor, the strength of the buried magnet, and the alignment of the sensor with respect to the magnet. A threshold detector senses the output of the sensor to indicate when a magnetic field is detected, and the peak analog output of the sensor is stored and compared to a reference after the sensor passes the magnet.

Abstract: A gear tooth sensor is provided which incorporates a magnet and two magnetically sensitive devices, such as Hall effect elements. The two magnetically sensitive devices are disposed in a common plane with each other with one of the devices being located at a position closer to the magnet than the other device. The common plane in which both magnetically sensitive devices are disposed is spaced apart from a central axis of the magnet by a predetermined distance. A divider is provided for determining a ratio of the magnetic field strengths that are imposed perpendicularly on the first and second magnetically sensitive devices. The ratio is used to distinguish between teeth and slots proximate the sensor wherein the common plane of the magnetically sensitive devices is generally perpendicular to the path along which the teeth and slots pass.

Abstract: A sensor for detecting faults in a magnetized ferrous body which has a first ferrite disc having at least two opposed sides, a pair of Hall Effect semiconductors, the Hall Effect semiconductors being affixed to opposite sides of said ferrite disc and a pair of ferrite discs, each ferrite disc of said pair of ferrite discs being affixed to a side of each of said Hall Effect semiconductors opposite the side of said Hall Effect semiconductors which is affixed to the first ferrite disc.

Abstract: The invention in one embodiment utilizes a pair of identical high energy permanent magnet dipoles mounted on parallel rotatable shafts. The magnetic dipoles lie in a plane perpendicular to the rotatable shafts, and the shafts are coupled to a drive motor for rotation in opposite directions. The magnetic dipoles gives rise to a resultant field which is the sum of the fields due to the individual dipole magnetic moments. With the dipoles aligned, a field having only a longitudinal component is generated, "longitudinal" being defined as being along the direction of initial alignment. The longitudinal components of the two dipoles add, being in the same direction, while the transverse (i.e. perpendicular to the longitudinal direction) components of the dipole cancel, as they point in opposite directions. In the region of space adjacent to the longitudinally defined direction, the longitudinal oriented field components still add, and the transverse components substantially, if not completely, cancel.

Abstract: Eddy current based method and apparatus uses a repetitive square wave signal applied to an excitation coil and operates in a pulse echo mode by gating the detected field signal at synchronized intervals to generate one or more sequences of like gated slices obtained from respective detector positions on a circular scan path. Suitable time gating to exclude surface and near-surface reflections overcomes surface clutter and flaws are detected by examination of the sequence of slices for characteristic changes in level. Both method and apparatus have special application for crack investigations at rivet fasteners or similar, e.g. in airframes, and have ability to cope with ferrous fasteners in non-ferrous material. Excitation coil and magnetic detector are combined in a probe and the latter is driven around a circular scan path. A centering display is derived by examination of the near-surface reflection signal to determine the position and level of the peak slice level on the scan path sequence of slices.

Abstract: An apparatus for locating magnetizable material (5, 6) within a structure (4) includes a scanning head (1) with a permanent magnet (28) for producing a magnetic field in the structure (4). Two field plates (30, 31), adjacent one another on only one pole face of the permanent magnet (28), are interconnected by a differential circuit and measure the magnetic field of the magnet disturbed by the magnetizable material (5, 6). The differential values measured by the pair of field plates form a differential measured signal for establishing, after differentiation, the location of the magnetizable material (5, 6) within the structure (4). The location of the magnetizable material (5, 6) within the structure can be shown on a monitor (7) of an evaluation unit (3).

Abstract: A magnetic sensor. A plurality of sensing parts are deposited and formed on an element substrate in film form. The inside two of the sensing parts are connected in series to use for a reading of a narrow pitch magnetic pattern, and the outside two of the sensing parts are also connected in series to use for a reading of a wide pitch magnetic pattern. The connection of the sensing parts is carried out by using terminals and wires. The terminals are provided so as to short-circuit the ends of the sensing parts or for every sensing part.

Abstract: A method for sensing an applied magnetic field uses a superconductor element with superconductive material as a sensor. The element is cooled to its superconducting state and current is supplied to the element. An applied magnetic field is applied to the superconducting material and an output from the superconductor element is fed to a feed back power source. In the feedback power source a comparison is made between an input voltage from the superconductive element and a reference voltage. Current is applied to a coil for applying a bias magnetic field to the superconductor element based on the comparison. With this method, the input voltage and the reference voltage are made as equal as possible. A superconductive device includes a coil for applying an AC power source and a coil for applying a DC power source.

Abstract: A direct-current electromagnetic device for nondestructively detecting localized discontinuities in ferromagnetic objects is disclosed. The device comprises an adjustable dc excitor means, a magnetic flux injector means, an external magnetic field detector means, a plurality of position sensors, a signal processing means and a control means. It is particularly adapted for detecting flaws in soiled and distorted ferromagnetic objects such as water wall tubes in industrial boilers. An apparatus incorporating the device and a method of detecting discontinuities are also disclosed.

Abstract: This invention relates to an apparatus and method for measuring the resistance of superconductors. Structures of this type, generally, allow the resistance of the superconductor to be accurately measured in a non-destructive manner by using a bifilar coil which includes an integrated loop/switch formed from the bifilar coil.

Abstract: A magnetic sensor disposed in an opposing relation to a magnetic scale magnetized at a grating pitch .lambda. in the length direction thereof and which is movable relative to the magnetic scale in the length direction is comprised of at least two magnetoeffect resistance elements disposed with a distance of (.lambda./2).multidot.n (n=1, 2, 3, . . . ) in the length direction, the two magnetoeffect resistance elements being formed in the width direction perpendicular to the length direction and each of the magnetoeffect resistance elements having partial magnetoeffect resistance elements distant from each other by a distance of (.lambda./2).multidot.(1/2m) (m=2, 3, 4, . . . ) from a predetermined position on the width direction perpendicular to the length direction, wherein the two magnetoeffect resistance elements are shaped as substantially symmetrical configurations relative to a central line in the length direction.

Abstract: A system for detecting and positioning objects, the electric conductivity of which differs from the surrounding medium thereof by measuring variations in an electric field generated into the medium. More precisely, the invention concerns a method and assembly for detecting objects or objectives, for example vessels, in electrically conductive medium, for example sea, by measuring changes, disturbances, signs, indications or the like caused by the object or objective, especially for surveying water fairways and/or extent.

Abstract: A Hall-effect sensor, wherein a Hall element is disposed in a magnetic path being formed by a magnet and a flux guide, and the magnet, flux guide, and Hall element are integrally held with a molded frame, and the Hall element is fixed to the magnet (or flux guide) or the molded frame. This Hall-effect sensor can easily position the Hall element with higher sensitivity.

Abstract: A Hall effect type sensing device comprises a magnetic circuit, a Hall transducing element arranged in the magnetic circuit to output a signal depending on a change in magnetic flux, a magnetic flux changing member which is able to change the magnetic flux in the magnetic circuit, a gap part which allows the magnetic flux changing member to move therein, and a frame member having its one side provided with a recessed portion forming the gap portion, and having its other side provided with an accommodation portion at a position adjacent to the recessed portion, the accommodation portion housing the Hall transducing element and a member forming the magnetic circuit.

Abstract: Apparatus for measuring hysteretic properties of thin film recording disks is provided which comprises a magnetic field generator for magnetizing a spot on a piece of magnetic material to be tested. The magnetized spot is moved past a stationary Hall effect sensor which detects the magnetic flux being emitted from the magnetized spot. The process of magnetizing and detecting the flux emitted from the same spot is repeated at different magnetization levels to provide a set of automatic measurements that are recorded in a memory of a controller processor. An analysis of the recorded data permits the automatic computation of residual flux, remanent coercivity, switching field distribution as well as other hysteretic properties.

Abstract: A probe comprises a magnet and a Hall element which are provided in a magnetically impermeable case. The Hall element is disposed at the midportion between the two poles of the magnet in parallel with the lines of magnetic force. The presence of a carburized portion in the member to be inspected and the depth of carburization are detected by passing d.c. current across the Hall element and detecting the Hall effect electromotive force produced between the two ends of the element which are opposed in a direction perpendicular to the direction of flow of the current.

Abstract: A method and apparatus for testing steel components for temperature embrittlement uses magneto-acoustic emission to nondestructively evaluate the component. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be umembrittled and a test component. Magnetic remanence is determined by applying a DC current to the electromagnets, then turning the magnets off and observing the residual magnetic induction.

Abstract: The area of a loop made of superconducting material is decreased to incre the magnetic field on the surface of a test piece adjacent the loop for determining the critical field, H.sub.c, of the test piece. A loop with a gap having a temporary plug placed therein in which a persistent current is established has a nozzle forming the gap thereon for receiving a test piece. The test piece then completes the circuit permitting removal of the temporary plug. The area of the loop is then decreased resulting in an increase in magnetic field at the surface of the test piece. When the critical field of the test piece is reached, magnetic flux will leak from the internal area of the loop, thereby determining the critical field of the test piece. A continuous length of superconducting material can be tested for discontinuities or spots of low critical field, H.sub.c.

Abstract: A method and apparatus for testing steel components for temper embrittlement uses magneto-acoustic emission to nondestructively evaluate the component. Acoustic emission signals occur more frequently at higher levels in embrittled components. A pair of electromagnets are used to create magnetic induction in the test component. Magneto-acoustic emission signals may be generated by applying an AC current to the electromagnets. The acoustic emission signals are analyzed to provide a comparison between a component known to be umembrittled and a test component. Magnetic remanence is determined by applying a DC current to the electromagnets, then turning the magnets off and observing the residual magnetic induction.

Abstract: An apparatus for measuring a carburized portion occurring in inside of a tubular article, the apparatus comprising a first detecting unit having opposite magnetic poles of a first magnet arranged in parallel to an inspecting face of a case made of nonmagnetic material and a magnetism detector disposed at an intermediate portion between the poles, a second detecting unit having opposite magnetic poles of a second magnet arranged perpendicular to the inspecting face of the case and a magnetism detector provided for one of the poles of the second unit, and a data processing circuit for processing the output signals from the first and second detecting units to produce a difference signal.

Abstract: A Hall-effect sensor, wherein a Hall element is disposed in a magnetic path being formed by a magnet and a flux guide, and the magnet, flux guide, and Hall element are integrally held with a molded frame, and the Hall element is fixed to the magnet (or flux guide) or the molded frame. This Hall-effect sensor can easily position the Hall element with higher sensitivity.

Abstract: A magnetoresistive sensor requires only two electrical connections to operate. The magnetoresistive sensor uses a hammerhead design and a barber pole array. Blocking capacitors are used to define two signal paths, one for a DC sense current, and one for an AC data signal. The blocking capacitors provide an electrical short to AC signals across wing regions of the magnetoresistive sensor. The blocking capacitors are fabricated directly upon a wafer which carries the magnetoresistive sensor.

Abstract: A magnetic sensor includes magnetic sensor elements arrange on the upper surface of a bobbin and an input/output section provided on the lower surface of the bobbin wherein the magnetic sensor elements and the input/output section are connected through a wiring pattern formed on the bobbin by electroless plating.

Abstract: A device for the direct visualization of surface and near surface cracks, voids, flows, discontinuities, etc. in a target material. A magnetic garnet epitaxial film is deposited on either side, or both sides, of a non-magnetic substrate. A reflective material is provided adjacent to the epitaxial film, and the substrate with its associated layers is placed over a sheet of current carrying material and this sheet is placed over the target material. A bias magnetic field is then applied to the substrate together with its epitaxial film. Polarized light is transmitted onto the substrate with its associated layers and is reflected through the epitaxial layer and back out of the substrate. The existing magnetization, within the epitaxial film, interacts with nearby magnetic fields associated with eddy currents flowing adjacent to flaws in the target material, such that the domain structure of the epitaxial film is altered.

Abstract: A magnetic sensor for use in measuring the position, velocity, and/or direction of movement of an object having alternating zones of magnetic conductivity with a permanent magnet member having a pole face facing the moving object and having an axis transverse to the direction of movement thereof. A ferromagnetic strip of high permeability is mounted on the face of the magnet coaxial therewith having a length dimension in the direction of movement of the object greater than the width dimension transverse to the direction of movement. The ferromagnetic strip distorts the field of the permanent magnetic member in the area of a pair of the sensor elements such that the flux lines in the area of each of the sensors are urged toward a transverse direction relative to the direction of movement of the object, whereby the flux field in the area of each of the sensor is uniform.

Abstract: A method and apparatus is provided for electromagnetically testing an elongate object such as a wire rope for cross-sectional area variations. The elongate object is magnetized over adjacent sections in opposing directions along a longitudinal axis of the elongate object. Variations in axial magnetic flux, which have been observed to be coincident with variations in the cross-sectional area of an elongate object, are measured by a plurality of non-inductive transducers. The transducers are interconnected to produce a composite signal. The composite signal is compared to a reference signal.

Abstract: In a process and an apparatus for determining the coercive field strength and the maximum pitch of the hysteresis cure in set-up techniques a test body is magnetized in a magnetic field of an exciter coil fed with an alternating current, as the hysteresis curve of the test body is traversed a number of times with the frequency of the alternating current and the tangential field strength on the test body surface generated by the exciter coil is detected continuously with the aid of a magnetic field strength sensor during the traversing of the hysteresis curve. From a harmonic analysis of the time course of the tangential field strength within one period there is calculated a distortion factor for the determination of the maximum pitch of the hysteresis curve.

Abstract: An apparatus for magnetically detecting a positional relation between first and second members the positions of which change relative to each other comprises a magnetic recording medium carried on the first member and a magnetic sensor substrate supported by the second member. Two or more tracks each including a multiplicity of magnetic poles arranged at a predetermined pitch are provided on the magnetic recording medium, corresponding to the respective phases of two or more detection signals to be detected by the apparatus and in a direction in which the positional relation between the first and second members changes. The magnetic poles in any one of the tracks are shifted with respect to the magnetic poles in the other track by an amount corresponding to a phase difference between the detection signal for the phase which corresponds to the one track and the detection signal for the phase which corresponds to the other track.

Abstract: Magnetic field sensing circuits including wire coils and Hall effect devices are provided which produce high-gain output for a relatively low change in perceived field intensity. Series connected plural Hall effect devices are connected to the coil and include amplifier and integrator circuits interposed at selected points between Hall effect devices to modify the output signal gain and passband. The circuits may include diode and capacitance elements to modify the circuit output signal.

Abstract: An improved magnetic sensor for use in measuring the position, velocity and/or direction of movement of an object having alternating zones in the direction of movement of different magnetic conductivity comprises a permanent magnet member having a pole face facing the moving object and having an axis transverse to the direction of movement thereof. A ferromagnetic strip of high permeability is mounted on the face of the magnet coaxial therewith and has a length dimension in the direction of movement of the object which is greater than the width dimension transverse to the direction of movement. A pair of sensor elements are mounted on the ferromagnetic strip, one on each of the opposite sides of the magnet axis in the direction of movement of the object.

Abstract: A magnetoelectronic transducer includes a housing; a circuit board (21) provided within the housing and having a processing circuit (51); an element holder (22) provided within the housing and extending perpendicular to and beyond the circuit board; a magnetoelectronic transducer element (24) provided on a front end of the element holder; a power circuit (50) provided on a basic section (22b) of the element holder; and a cable (28) connected to the power circuit.

Abstract: Measurement of a physical property such as coercive force of a member to be inspected is performed at a plurality of locations in one region of the member. Similar measurement is performed in a plurality of different regions of the member and a maximum or minimum value (extreme value) is determined for each of the regions. On the basis of the extreme values thus determined, a recurrence period is determined in accordance with an extreme value statistic theory with the aid of a computer, whereon an estimated maximum value of the physical property of the member as a whole is determined from the recurrence period. On the basis of the estimated maximum value, the degree of deterioration of the member is predicted by the computer by consulting the data indicating the previously determined relation between the physical property and the degree of deterioration.

Abstract: In construction of a magnetic encoder used for detection of displacement of a mobile body, a circular magnetized pattern is formed on one longitudinal end face of a magnetic rotary spindle mechanically coupled to the mobile body, and a magnetic sensor faces the magnetized pattern with a prescribed gap. Direct formation of the magnetized pattern on the rotary spindle excludes production errors caused by the conventional coupling process and end-face magnetization assures significant compactness of the entire construction.

Abstract: A ferrous object sensor assembly is capable of sensing the presence or absence of an object of high magnetic permeability, such as a tooth or notch on a rotatably mounted ferrous wheel at zero speed and immediately upon power-up and, thus, may also be used as a proximity sensor. The ferrous object sensor assembly is comprised of a permanent magnet and a magnetic flux responsive sensor having a sensing plane which produces an electrical output signal which varies as a function of the change in magnetic flux density. The ferrous body sensor assembly does not rely upon pole face magnetism as some known conventional sensors but, rather, relies upon a the radial component of magnetic flux density emanating from a lateral surface of the magnet, intermediate opposing pole faces. Since the ferrous object sensor assembly does not rely on pole face magnetism, its electrical output signal is relatively stable over a relatively wide temperature range.

Abstract: Relatively minute changes in magnetic field intensity are sensed by a circuit including a wire coil connected to a Hall effect element to provide the bias current to the element. The Hall effect element is disposed in the magnetic field with the coil and the output signal of the element is proportional to the square of the intensity of the magnetic field. The circuit is included in a device for measuring magnetic anomalies such as stress or corrosion cracks in structures of magnetic material including fluid transmission pipelines.

Abstract: A position sensor for measuring the separation, in a givne direction (Oy), between a first part such as a datum element of a railway vehicle axle and a fixed second part such as a rail on which said axles runs, includes magnets (11, 12) for producing a magnetic field above the second part (10) and Hall effect probes (15) for measuring the value of the component of the field in said given direction (Oy) with variation in that value being proportional to the separation.

Abstract: The invention relates to a novel apparatus for detecting as well as quantifying superconductivity characterized by a rigid-stemmed pendulum used to support the superconductive sample for free-swinging movement about a low-friction fulcrum in a magnetic field effective to swing the pendulum to one side, connecting both a first mechanism to the pendulum operative to sense the movement of the pendulum and generate a signal proportional thereto along with a second mechanism effective to receive such a signal from the first mechanism and react thereto in a manner to null the movement of the pendulum along with the sample suspended therefrom, and, finally, connecting a signal processing mechanism into the system whereby the signal generated by the first mechanism is quantified as a measure of the superconductive properties of the sample.

Abstract: A Hall elements and magnet assembly for use as a proximity detector includes a magnet, a pole piece mounted to one pole end of the magnet and an integrated circuit having two side-by-side Hall elements, an amplifier, interconnecting wiring providing the difference voltage between the two Hall output voltages at the input of the amplifier, and a Schmitt trigger circuit. The integrated circuit is mounted to the pole piece at the pole end of the magnet. The pole piece is a ferromagnetic member which is thinner in the center than at the periphery for achieving a highly uniform field strength across the surface of the magnet pole end toward reducing the criticality of the position of mounting of the integrated circuit in manufacturing and for extending the range of gap dimensions between a passing ferromagnetic article and the assembly for which proper detection of the passing article can be made to occur.

Abstract: A method and apparatus is provided for electromagnetically testing an elongate object such as a wire rope for cross-sectional area variations. The elongate object is magnetized over adjacent sections in opposing directions along a longitudinal axis of the elongate object. Variations in axial magnetic flux, which have been observed to be coincident with variations in the cross-sectional area of an elongate object, are measured by using saddle coils which are positioned adjacent the magnetized sections of the elongate object and which detect variations in radial flux. The saddle coils are positioned to have first half circumferential windings located where the magnetic flux density in the elongate object is at a maximum value and second half circumferential windings located where the magnetic flux density in the object is zero.

Abstract: The subject of the invention is a device for non-destructive testing of long bodies (14) for structural faults by means of magnetizing the respective body (14). At least one magnetic field is directed onto the body (14). The structural faults in the body cause changes in the magnetic field pattern. The changes are picked up by magnetic field sensors (50, 52) arranged on or near the body surface. The respective body (14) is moved through the magnetic field, which has an inclination of preferably 45.degree. to the transportation direction (26) of the body (14). The magnetic field sensors (50, 52) are oriented transverse to the direction of the magnetic field.