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3973191 Inductive displacement sensor apparatus  
A variable inductor having a U-shaped magnetic core with a short-circuiting plate providing a short-circuiting ring for both legs of the core movable along the core legs in response to a...
3971982 Plural frequency multi-phase transducer arrangement for detecting the presence and location of faults in a metal body and compensating for body movements  
Improved apparatus for detecting and locating defects in metal bodies of the type in which the body under test is difficult to keep centered in which a multi-phase transducer coil induces currents...
3962627 Electronic apparatus for testing moving coins employing successive time significant sensings of the effects of proximity of a coin under test to inductive impedance elements upon the effective impedances thereof  
An improved method and apparatus for testing coins, metallic credit tokens and similar objects, capable of determining both type or denomination and genuineness thereof, utilize the effect upon the...
3953791 Apparatus for and method for testing the number of turns on a coil  
Apparatus and method for testing the number of turns on a coil by magnetically energizing a rod through an energizing coil and with compensating coils modifying the flux about the rod to provide a...
3949293 Apparatus and method for detecting a moving metal mass including means to discriminate signals having a particular period  
In an electronic detection system, signals indicative of a detected mass of material are related to a selected mass velocity and a detection aperture through which the mass is moved. The pulse...
3936734 Method for contactless measurement of conductivity and/or temperature on metals by means of eddy currents  
A method for contactless measurement of conductivity and/or temperature on metals by means of the eddy current effect induced within the metal by an alternating magnetic field produced by an...
3936739 Method and apparatus for generating error corrected signals  
A method and apparatus for automatically generating error corrected pulses in response to particle pulses which are subject to error due to coincidence. The subject apparatus includes a generator...
3926053 Apparatus for non-contact, accurate and continuous determination of surface temperature on a part  
Apparatus for non-contact, accurate, and continuous determination of the surface temperature on a rotatable part which includes a sensing probe unit containing detecting means for both temperature...
3925725 Oscilloscopic ferrometer  
An oscilloscopic ferrometer comprising a magnetizing system in the form of a stepdown transformer having a single-turn secondary winding and at least two ellipsoidal solenoids connected thereto and...
3890564 Apparatus for inducing eddy current in a semiconductor wafer for measuring the electric conductivity or resistivity thereof  
An apparatus for measuring electric conductivity or resistivity of a semiconductor wafer with no electric contact to the wafer, which comprises an exciting circuit including a first exciting coil...
3863141 Frequency analyzing apparatus for use with an eddy current detector  
A frequency analyzing apparatus comprising an amplifier, a negative feedback circuit connected between the input and output terminals of the amplifier and a positive feedback circuit having a...
3835374 METHOD AND APPARATUS FOR PROVIDING SPEED COMPENSATION FOR INFORMATION CONTAINING SIGNALS IN WHICH THE THRESHOLD LEVEL OF THE DETECTOR IS VARIED PROPORTIONAL TO SPEED  
Certain types of equipment, for example, certain types of instrument pigs used for detecting flaws in or other characteristics of pipelines, employ sensing devices that derive...
3758849 METAL DETECTOR SYSTEM HAVING IDENTICAL BALANCED FIELD COIL SYSTEM ON OPPOSITE SIDES OF A DETECTION ZONE  
A balanced field metal detector apparatus comprising a coil assembly including planar, generally rectangular loop configured multi-turn field and sensor coils disposed in partially overlapping...
3750010 VIBRATION ANALYZER PROBE WITH REDUCED TEMPERATURE SENSITIVITY  
Disclosed is a simplified and inexpensive probe for non-contacting vibration analyzers, and an analyzer employing the probe, which probe is substantially insensitive to temperature variations. The...
3745449 METHOD AND APPARATUS FOR TESTING WELDED PIPE FOR ANOMALIES WITH MEANS TO CHANGE THE SENSITIVITY WHEN TESTING THE WELDED AREA  
Apparatus and method for nondestructively inspecting a tubular member of uniform wall thickness having a weld line extending throughout its length. Complete circumferential inspection is...
3721859 METAL OBJECT SENSOR, PARTICULARLY FOR RAILWAY WHEELS  
A sensor for sensing movement of a metal object, such as a railway wheel, along a given path, comprising three sensing coils, all tuned to the same operating frequency, spaced along the path with...
3715659 INDUCTIVE NON-CONTACT VIBRATION ANALYZER WHICH IS INDEPENDENT OF STANDOFF DISTANCE  
Disclosed is a non-contact vibration analyzer that is substantially independent of standoff distance. An inductive probe produces an electrical output having AC and DC components that vary...
3714558 MAGNETIC SENSOR FOR DETECTING BREAKS IN A STEEL ROPE INCLUDING MULTIPLIER FOR ELIMINATING NOISE  
Apparatus for detecting wires in a steel wire winding rope in which the rope is passed through a magnetic field and sensing coils are employed to detect any magnetic dipoles created between the...
3696290 MAGNETIC NON-CONTACT THICKNESS GAUGE WITH MEANS TO COMPENSATE THE EFFECTS OF STRAY FIELDS ON THE GAUGE  
A thickness measuring device wherein means are positioned at opposite sides of and in selected spacing relative to a work piece being measured and respectively include magnet responsive means...
3686563 APPARATUS UTILIZING AN AIR CORE TRANSFORMER FOR DETERMINING MAGNETIC MATERIAL CONTENT OF A SUBSTANCE  
An air-core transformer is adapted to receive a sample of the substance to be tested for content of magnetic material, e.g., the mineral magnetite. It is supplied, usually through load-isolating...
3619805 NONCONTACTING DISPLACEMENT TRANSDUCER INCLUDING AN OSCILLATOR WITH CABLE-CONNECTED INDUCTIVE PROBE  
Disclosed is an eddy-current-type noncontacting displacement transducer and gage for gaging the distance between a probe tip and a metallic surface. The transducer comprises a modified common base...
3611120 EDDY CURRENT TESTING SYSTEMS WITH MEANS TO COMPENSATE FOR PROBE TO WORKPIECE SPACING  
A nondestructive testing system is disclosed for inspecting the surface of a workpiece for hidden defects. The system includes a probe for creating eddy currents in the surface and precisely...
3609735 INDUCTIVE-CAPACITIVE PROBE IN MACHINE FOR HANDLING SHEETLIKE MATERIAL  
Machine for handling sheetlike material, such as a printing press and a sheet feeder therefor, having a combined inductive-capacitive probe for discriminating among the presence of a single...
3573784 METAL DETECTING APPARATUS FOR CONVEYOR BELT  
For detecting metal traveling along a conveyor belt, an excitation coil and a pair of pickup coils are positioned adjacent the belt. A signal voltage is induced in the pickup coils whenever a...
3541394 PROXIMITY TRANSDUCER  
3532971 FEEDBACK SYSTEM FOR AUTOMATIC RANGE COMPENSATION OF A TRANSDUCER  
3502968 EDDY CURRENT INDUCTIVE FLATNESS MEASUREMENT DEVICE  
3496458 METHOD AND APPARATUS FOR DETECTING AND MEASURING CRACKS IN METAL STRUCTURES  
3496457 SIGNAL NORMALIZATION APPARATUS FOR PIPELINE LOGGING  
3449661 EDDY CURRENT TESTING SYSTEM HAVING LIFT-OFF COMPENSATION,AND UTILIZING A TUNED PLATE-TUNED GRID OSCILLATOR  
3424976 MAGNETIC DEVICE FOR DETERMINING DEFECTS IN ROD-LIKE ELEMENTS,CABLES,STEEL PIPES AND THE LIKE  
3394303 Eddy current inspection apparatus and method of calibrating  
3389333 Control system for maintaining a desired magnetic field in a given space  
3378763 Eddy current probe with temperature compensation  
3358225 Lift-off compensation for eddy current testers  
3346807 Reciprocating apparatus with means to maintain the reciprocation centered over an anomaly  
3345563 Method and apparatus for measuring true discontinuities in members of varying thickness by compensating for the effect of thickness on such measurements  
3328681 Electromagnetic flow detection apparatus with velocity compensation  
3244970 Electrical circuits for sockets usable with pluggable modules for flaw detection  
3197693 Nondestructive eddy current subsurface testing device providing compensation for variation in probe-to-specimen spacing and surface irregularities  
3170112 Magnetic circuit means and alloy components of constant magnetic permeability therefor  
3080507 Apparatus for stabilizing magnetic fields  
3078412 Apparatus for indicating the metal oxide content of a liquid metal  
3058058 Magnetic concentricity gage  
3052837 Pipe finder  
3042857 Electromagnetic prospecting apparatus  
3024412 Magnetic measuring instrument  
2980849 Sensing head for weld seam testing apparatus  
2945379 Accelerometer and magneto-resistive electromechanical transducer used therein  
2928044 Recording magnetometer