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4949037 System for detecting metal in articles using phase change of detection signals  
In a system for detecting stray metal in an article, the article passes through an alternating magnetic field generated from a coil. The magnetic field is detected by coils which generate induced...
4945446 Magnetic field compensating apparatus  
A magnetic field compensating apparatus having a plurality of compensating units comprising a plurality of serial coils each of which is disposed concentrically along the main magnetic field and...
4945307 Electronic device for detecting irregularities in a surface of a solid object  
A device for detecting irregularities in the surface of an object comprises at least one transducer which is movable relative to the surface of the object and an associated signal-processing unit...
4943770 Device for accurately detecting the position of a ferromagnetic material inside biological tissue  
A device for accurately detecting and monitoring the position of an object inside biological tissue, particularly an endotracheal tube inside a patient's throat, comprising a circuit which...
4944028 Non-contact type pattern sensor with variable clearance compensation  
An improved non-contact type pattern sensor includes a magnetic resistor element arranged facing a pattern track on a recoridng medium having a magnetized pattern in the pattern track. A clearance...
4939448 Electric current sensing device of the magnetic field compensationtype  
A magnetic circuit is coupled with a primary conductor in which flows the current to be sensed. The magnetic circuit has an air gap with a magnetic field detector and is coupled with a measuring...
4932615 Railroad track simulator for assessing track signal susceptibility to electric power line interference  
A railroad track segment simulator for assessing track signal susceptibility to electric power line interference including a circuit including a series dc resistor, a series inductor, and an...
4926123 Precision variable pitch compensation winding for displacement transducer  
A compensation winding for improving the linearity of a displacement transducer. The displacement transducer is the type having an electrically conducting non-ferromagnetic wall which moves in...
4926127 Apparatus for the detection of metal objects located within a poor electrically conductive environment  
A wire loop of almost negligible inductance is coupled with the excitation and receiver coils of metal object detection apparatus which is opened and closed to produce signals in phase with noise...
4924182 Eddy current method to measure distance between scanned surface and a subsurface defect  
This invention relates to a method for nondestructive inspection (NDI) of mposite materials comprising conductive fibers. The depth of broken fiber damage in nonmetal matrix composites such as...
4922201 Eddy current method for measuring electrical resistivity and device for providing accurate phase detection  
This invention relates to a method and device for measuring the resistivity f materials. In particular, the methods measure resistivity in carbon fiber reinforced composites as well as any...
4914366 Positioning control system  
A plurality of speed-sliding compensation amount functions are stored in a sliding compensation amount data memory and one of these functions is selected in response to input of a selection signal....
4893079 Method and apparatus for correcting eddy current signal voltage for temperature effects  
An apparatus and method for measuring physical characteristics of an electrically conductive material by the use of eddy-current techniques and compensating measurement errors caused by changes in...
4882538 Device for detecting current flowing in an electric wire  
A current detecting device for detecting current flowing in a first electric wire arranged close to a second electric wire having a portion extending in a predetermined direction. The device...
4878019 Electrical sensing system for measuring ferrous particles within a fluid with temperature compensation circuit  
A magnetic sensor for the collection and measurement of ferrous particles through the use of an electronic tuned circuit is disclosed. The sensor contains an electrical inductance along with an...
4872124 Length measuring device  
At the start of measurement by a length measuring device, a calibration coil in which the temperature characteristics are known, is connected to an oscillator. The oscillation frequency of the...
4868499 Object detector with feedback which holds constant the product of the transmitter coil current and frequency to maintain constant sensor voltage output  
An object detector uses product feedback in order to eliminate false indications of the presence of an object due to a change in operating frequency and/or transmitter coil current. The alternating...
4868909 Signal shaping circuit utilizing a magneto-resistor in a voltage divider circuit  
A circuit for deriving a temperature-independent square-wave signal from a measurement signal which consists of a DC component and an AC component and which is taken across a magneto-resistor...
4866378 Displacement transducer with opposed coils for improved linearity and temperature compensation  
The relative displacement of two bodies is measured by moving an electrically conducting, non-ferromagnetic wall means in proportion to the relative movement of the bodies in order to increase its...
4864235 Phase-selective monitoring via vector transformation  
A defect-sensing device for a test object, e.g. for detecting cracks in metal bodies with the aid of the eddy-current technique, has improved phase-selective properties by adding at least one...
4864232 Temperature compensation for displacement transducer  
A temperature compensation structure for a displacement transducer of the type having a coil and an electrically conducting, non-ferromagnetic wall moving in telescoping relationship with the coil...
4859942 Circuit arrangement for sensing the displacement of a movable iron core relative to a magnetic coil by measuring the decay time of a constant current flowing through the magnetic coil  
The arrangement comprises, a circuit arrangement for measuring the inductance of an inductive displacement or position sensor having a magnetic coil and a magnetic circuit including a movable iron...
4857842 Temperature compensated hall effect position sensor  
A temperature compensated position sensor which may be used with hydraulic and pneumatic actuators having a magnetic piston and a non-magnetic cylinder is disclosed. The position sensor comprises a...
4855676 Ferromagnetic eddy current probe having transmit and receive coil assemblies  
An eddy current probe capable of detecting localized defects in a ferromagnetic tube is disclosed. The probe employs a transmit coil assembly and a receive coil assembly. Means for magnetically...
4855678 Apparatus for guiding the sensor holder of a surface testing apparatus  
An apparatus by which a sensor holder of a surface testing apparatus can be moved along a preselected path of movement over the surface to be examined. The apparatus has a guide rail establishing...
4853634 Device for crack detection on hot cast billets and suppressing the effects of magnetic regions  
An electrical defect testing device for a non-magnetic test object, for example crack detection on hot continuously cast billets, is provided with means for detecting and suppressing the influence...
4849693 Automated measurement system employing eddy currents to adjust probe position and determine metal hardness  
A system for measuring the hardness of cartridge cases employs an eddy current probe for inducing and sensing eddy currents in each cartridge case. A first component of the sensed signal is...
4843316 Nondestructive M-H hysteresis testers for magnetic discs for computer disc drives  
The manufacture of digital magnetic recording discs for computer disc drives requires the monitoring and control of the M-H hysteresis loop properties of the magnetic film deposited on the disc...
4843318 Distance compensation in magnetic probe testing systems wherein object to probe spacing is employed as an exponent in excitings probes or processing probe outputs  
A system is disclosed for nondestructive object testing comprising a magnetic probe responsive to an excitation signal for generating a magnetic field and thereby inducing eddy-currents in the...
4837510 Device for suppression and/or separation of signals due to magnetic oxide scales in hot cast billets  
Defect detecting equipment includes a device which detects the presence of, for example, disturbing magnetic material such as cold oxide scales in a test object, in order thus to control, for...
4833406 Temperature compensated Hall-effect sensor apparatus  
A temperature compensated Hall-effect sensor apparatus is disclosed which senses the position of a moving body and provides an output signal indicative of the position of the moving body. The...
4829250 Magnetic direction finding device with improved accuracy  
A system for determining the relative orientation in three dimensions between a fixed frame of reference and an unconstrained object. Mutual coupling between three orthogonally disposed...
4827216 Differential triple-coil tester for wire rope with periodic lay effect cancellation  
An electrical coil driven by an alternating current develops an alternating magnetic field. A segment of a wire-rope specimen is placed next to and on the axis of the coil, but perpendicular to the...
4827217 Low noise cryogenic apparatus for making magnetic measurements  
Apparatus for performing sensitive magnetic measurements using cryogenically cooled instrumentation, wherein the instrumentation is separated from the bubbles present in a cryogenic cooling fluid....
4823081 Interference magnetic field compensation method which includes supplying a current to a coil to compensate the field  
Method for compensating the interference magnetic field of an object by means of an interference field controlled magnetic self-protection system having a coil system connected to receive a...
4823082 Signal processing method for an electromagnetic induction test  
A signal processing method in an electromagnetic induction test. A test object is subjected to an electromagnetic induction by use of N (N≥1) kinds of test frequencies to obtain M (M≤2N) kinds...
4814704 Rotor position indicator with correction for apparant acceleration and deceleration  
In one aspect of the present invention, an angle measuring device is described for measuring the angle of a rotating rotor having a plurality of markings spaced thereabout. The device comprises: a...
4814705 Method and apparatus for magnetic discontinuity detection in a specimen of magnetizable material  
A method and an apparatus are provided for detecting magnetic discontinuities, for example corrosion pits, in a specimen of magnetizable material. A horseshoe shaped magnet (32) is supported with...
4814702 Process for accurately determining the position of the edges of support plates in steam generators  
A process for using an eddy current probe to precisely locate the edges of a baffle plate or support plate which surrounds a tube of a heat exchanger is disclosed herein. The process generally...
4812757 Method and device for accurately determining the distance of a magnetic sensor from a conductive reaction rail  
In magnetic bearings and magnetic suspension devices, sensors (4), as they are used for bearing regulation of support and guide magnets in magnetic transportation technology, continuously measure...
4808927 Circumferentially compensating eddy current probe with alternately polarized receiver coil  
An eddy current probe capable of detecting localized defects with 100% circumferential coverage in tubes, tubes under support plates etc., is disclosed. The probe employs multiple receiver coils...
4804913 Positioning control system for a fluid powered cylinder  
A coil assembly including primary coils disposed at predetermined locations axially spaced from one another and secondary coils provided in association with these primary coils is fixed at one end...
4798920 Stylus coordinate determining device with distortion compensation  
In a coordinates detecting device comprising: a cursor; a tablet in which conductors are arranged in a predetermined periodic pattern; and arithmetic means for calculating the position of the...
4792755 Process and apparatus for the non-destructive examination of ferromagnetic bodies having sections of surface adjoining each other along edges and/or at corners  
This invention relates to a process and an apparatus for the non-distructive examination of ferromagnetic bodies having sections of their surface adjoining along edges. The bodies or body parts are...
4789826 System for sensing the angular position of a rotatable member using a hall effect transducer  
Angular rotation of a member, such as the shaft of a tension arm assembly, is sensed by the combination of a circular type of magnet secured to the rotatable member and selectively polarized...
4779048 Metal detector for detecting metal objects  
A metal detector is proposed, in which field coils and receiving coils are arranged on either side of a zone to be monitored. In order to bring about a more uniform sensitivity distribution within...
4771238 Device for measuring, without contact, the thickness of metallic materials at temperatures above the Curie temperature  
The sensor is constituted by a magnetic core with pole pieces and by an electric coil wound on the body of said core. With said coil there are associated a sinusoidal current generator and...
4763070 Method and apparatus to compensate for lateral changes of a ferromagnetic body during magnetic testing  
A method and a device for non-destructive testing of ferro-magnetic bodies for structural faults by means of magnetization. The structural faults cause changes in the magnetic field which are...
4752733 Compensating circuit for a magnetic field sensor  
A circuit which compensates for fluctuations in the transfer characteristic of a magnetic field sensor is disclosed. More particularly, an auxiliary magnetic field is generated preferably by a coil...
4746859 Power and temperature independent magnetic position sensor for a rotor  
In order to optimize the electrical performance in motors in terms of improved efficiency, power factor, and reduced current, a power and temperature magnetic position sensor for a rotor utilizes...