Abstract: Examples of systems and methods for calibrating or operating a magnetic sensor for sensor temperature or operating conditions are provided. The magnetic sensor can comprise a dual magnetometer sensor that comprises a first, low-power-consumption magnetometer (e.g., a magneto-inductive magnetometer) and a second higher-power-consumption magnetometer (e.g., a magneto-resistive magnetometer). The second magnetometer can have a lower unit-to-unit variation in temperature calibration parameters and can be used to temperature-correct readings from the first magnetometer. The magnetic sensor can dynamically switch between usage of the first magnetometer and the second magnetometer in order to provide a dynamic sample rate that can depend on conditions within the sensor or external to the sensor.

Abstract: A power generation element includes a magnetic member that produces a large Barkhausen effect and magnetism collection members including an insertion part having the magnetic member inserted therethrough. The magnetism collection member includes a first component on an opposite side of a boundary plane to a magnetic field generation unit and a second component on the same side of the boundary plane as the magnetic field generation unit, the boundary plane passing through a center of an imaginary circle inscribed in the insertion part and having a diameter equal to a length of the insertion part in a third direction perpendicular to first and second directions, the first direction is a direction of the insertion of the magnetic member, and the second direction is a direction in which the magnetic field generation unit is disposed. A volume of the second component is larger than a volume of the first component.

Abstract: Examples of systems and methods for calibrating or operating a magnetic sensor for sensor temperature or operating conditions are provided. The magnetic sensor can comprise a dual magnetometer sensor that comprises a first, low-power-consumption magnetometer (e.g., a magneto-inductive magnetometer) and a second higher-power-consumption magnetometer (e.g., a magneto-resistive magnetometer). The second magnetometer can have a lower unit-to-unit variation in temperature calibration parameters and can be used to temperature-correct readings from the first magnetometer. The magnetic sensor can dynamically switch between usage of the first magnetometer and the second magnetometer in order to provide a dynamic sample rate that can depend on conditions within the sensor or external to the sensor.

Abstract: Axial magnetic flux sensors are described. The axial magnetic flux sensors comprise multiple substrates with conductive traces on them in some embodiments, and in other embodiments a single substrate or no substrate. When multiple substrates are provided, the substrates couple together such that the conductive traces connect to form a coil. The coil may be a continuous, multi-loop coil. When the substrates are coupled together, they may define an opening to accommodate a shaft or other piece of equipment.

Abstract: A method for determining the relative position of a metal object in relation to a user device and to a transmitter antenna of an inductive charging support when charging the user device. The method includes measuring the quality factor of the transmitter antenna, measuring the quality factor of the receiver antenna, and comparing the measured quality factor of the transmitter antenna with a predetermined quality factor threshold of the transmitter antenna and comparing the measured quality factor of the receiver antenna with a predetermined quality factor threshold of the receiver antenna so as to deduce therefrom the relative position of the metal object in relation to the user device and to the transmitter antenna or the absence of an interfering metal object.

Abstract: A locating system is presented. In some embodiments, the locating system includes a first platform, the first platform including a transmitter capable of inducing a current in a line; a second platform, the second platform including a receiver capable of detecting the current in the line; and a processor coupled to the first platform and the second platform, the processor directing the first platform and the second platform to control their motion over the line and collecting location data of the line.

Abstract: An electromagnetic field controlling system and method are provided. The electromagnetic field controlling system includes a magnetic field sensor that is disposed proximate to or in a vehicle that charges electric power using a wireless charging system and is configured to detect the magnitude of an electromagnetic field. An output controller adjusts output power in a power transmission side of the wireless charging system based on a comparison between a predetermined value for an electromagnetic field and the magnitude of the electromagnetic field detected by the magnetic field sensor. Accordingly, the magnitude of an electromagnetic field output from a vehicle wireless charging system is controlled within a safe range.

Abstract: A high-Q human-portable, battery-powered self-correcting tunable resonator in a transmitter apparatus for inducing alternating currents of high quality in buried conductors to facilitate their location is disclosed. The transmitter apparatus may employ an FET-driven capacitive tuning circuit and a coil design that achieves high precision, high-quality transmission signals, and which may be equipped with a high-voltage booster for facilitating fault-localization applications.

Abstract: Apparatus for implementing Adjustable Compensation Ratio (ACR) active shielding or control of physical fields (magnetic, electric, electromagnetic, acoustic, etc.), comprising the addition of a secondary internal feedback loop within a conventional primary closed feedback loop topology. Compensation-ratio transfer function order and coefficients adjustment permits accommodating frequency-dependent and frequency-independent effects within a Protected Volume when a system field sensor or sensor array is not at the exact location where external field interference must be optimally canceled. A Laplace polynomial term precisely sets this parameter in a supplementary feedback link by modeling the frequency-dependent characteristic of an Interacting Medium without deleterious effect on other desirable primary closed-loop characteristics. The inventive ACR can be used in advanced active cancellation for magnetic shielding purposes.

Abstract: Disclosed herein is a pulse transformer that includes a drum core having a winding core portion and first and second flange portions, a plate core connected to the first and second flange portions, and a plurality of wires that are wound around the winding core portion. The first and second flange portions and the plate core are ground such that an inductance of the pulse transformer is 350 ?H or more when a bias current of 8 mA is applied to the wires.

Abstract: A system by which the proportion of ferromagnetic particles in a dielectric medium is measured. A magnetic field is generated by two signals in the medium: a low frequency feed and a relatively high frequency excitation. The feed magnetizes the ferromagnetic particles in the medium to the nonlinear range of the magnetization curve. The excitation is generated so that its spectrum is relatively wide and it is dense with frequency components. The level of the excitation is so high that the magnetic flux density in the medium corresponding to the excitation fluctuates nonlinearly, when the feed is at its peak value or near this. The magnetic field of the medium is measured by a secondary winding, and from the response signal produced by the sensor is detected the part resulting from the magnetic non-linearity, which part is the output signal. In the detection the response is multiplied by the signal, which arises magnetic field and includes the same random fluctuation as the response.

Abstract: A sensor comprises a housing which defines a measuring side and a connection side, a coil (6) which is arranged in the housing (1) on the measuring side, and a cover (14) for closing the housing on the measuring side. The housing (1) consists of ferromagnetic material, in particular ferromagnetic steel. The coil (6) is positioned and fixed in the housing close to the cover (14) or directly on the cover (14).

Abstract: A magnetic element control device of the present invention includes an excitation signal generation unit that generates an alternating signal, a feedback signal conversion unit that converts a time width between detection signals of a positive voltage and a negative voltage into voltage information, an adjustment signal generation unit that generates an offset signal that cancels an offset component which is superimposed on a data signal indicating a magnetic field intensity, and an excitation signal adjustment unit that generates an alternating current, a feedback current, and an offset current from the alternating signal, the feedback signal, and the offset signal, respectively, superimposes the feedback current and the offset current on the alternating current, and generates an excitation current which is applied to an exciting coil.

Abstract: A magnetic element control device controls a magnetic element during detection of an intensity of a stationary magnetic field by a time-resolved magnetic balance system where the magnetic field is applied to a flux-gate magnetic element that is constituted of an excitation coil and a detecting coil. The magnetic element control device includes: an excitation signal generator; an excitation signal adjuster; a detection signal comparator; a feedback signal converter; a feedback signal adjuster; and a data signal converter. The excitation signal adjuster superimposes a feedback signal on an alternating voltage signal and thereby generates an excitation signal, and applies the generated excitation signal to the excitation coil.

Abstract: A magnetic immunoassay system with a mechanism for compensating the direct current residual magnetic field in the vicinity of the specimen measurement position, in a direction perpendicular to the magnetic marker direction of magnetization for the measurement target. This invention reduces the effects of the magnetic field emitted from the unbound magnetic marker due to the residual magnetic field in the specimen solution and detects with high sensitivity the signal of the bound target magnetic marker. The magnetic field at the measurement position is regulated so as to intersect the direction of magnetization of the magnetic marker for the measurement target, in order to make the magnetization direction of the magnetic marker that is unbound due to residual magnetism or remanence in the sample solution, intersect the magnetization direction of the magnetic marker for the measurement target.

Abstract: A printed circuit in which, in going from one end to another, a same conductive line is wound successively: around the first winding axis to form at least one half-turn of a first coil, then around the second winding axis to form at least one half-turn of a second coil, then around the first winding axis to form at least one half-turn of a first coil, then around the second winding axis to form at least one half-turn of a second coil.

Abstract: Methods and apparatus for magnetic field sensor having a sensing element, an analog circuit path coupled to the sensing element for generating an output voltage in response to a magnetic field applied to the sensing element, and a coil in proximity to the sensing element, the coil having a first terminal that is accessible external to the magnetic field sensor.

Abstract: There is provided a shield-structured loop element which can suppress noise via a silicon substrate and can be manufactured by a semiconductor process. The loop element includes: a first well of a first polarity that is formed on a substrate; a deep well of a second polarity that is formed below the first well; a ring-shaped second well of a second polarity that is formed on the deep well along an outer periphery of the deep well; a third well of the first polarity that is formed in an island area surrounded by the deep well and the second well; a looped conductor that is formed in a layer above the third well and has smaller outer dimensions than those of the third well; and a first path that connects the second well to a bias power supply. The second well and the deep well are electrically connected to each other.

Abstract: A differential transformer type magnetic sensor includes a drive coil, a reference coil, and a detection coil. These coils are formed by repeating a linear pattern that is formed on the first surface, penetrates the board, is formed on the second surface, penetrates the board, and returns to the first surface. The reference coil is disposed at a side of one end of the drive coil, and the detection coil is disposed at a side of the other end of the drive coil. Induced current flows to each of the reference coil and the detection coil due to magnetic flux generated as drive current flows to the drive coil. The reference coil and the detection coil are electrically connected so that a direction of the induced current flowing along the reference coil and a direction of the induced current flowing along the detection coil are opposite to each other.

Abstract: A differential transformer type magnetic sensor includes a first coil layer, a second coil layer, and an insulating layer formed between the first coil layer and the second coil layer. The first coil layer includes a detection coil and a first drive coil. The second coil layer includes a reference coil and a second drive coil. The first drive coil and the second drive coil are electrically connected together so that a direction of drive current flowing in the first drive coil is the same as a direction of drive current flowing in the second drive coil. The detection coil and the reference coil are electrically connected together so that a direction of induced current flowing in the detection coil is reverse to a direction of induced current flowing in the reference coil.

Abstract: A measuring circuit system in a magnetic field measuring apparatus of the invention has an amplifier and a band-pass filter connected in sequence on an output terminal side of the TMR element, the band-pass filter is a narrow-range band-pass filter such that a peak pass frequency of the filter that is a center is a basic frequency selected from a range of 10 to 40 GHz and a band width centered around the basic frequency is a narrow range of ±0.5 to ±4 GHz; and with the measuring circuit system, an S/N ratio (SNR) of 3 dB or greater is obtained, the SNR being defined by a ratio of an amplitude S of a high-frequency generated signal induced by the TMR element to a total noise N that is a sum of a head noise generated by the TMR element and a circuit noise generated by the amplifier. With such a configuration, an in-plane high-frequency magnetic field generated by a microwave-assisted magnetic head is reliably and precisely measured.

Abstract: A magnetic spectrometer is integrated in a semiconductor substrate and provides high sensitivity without using an external magnet field. The spectrometer includes one or more highly stable on-chip oscillator and LC resonator. A current caused to pass through the inductor generates a magnetic field and polarizes the nanoparticles placed in its proximity, thereby changing the effective inductance of the inductor, and in turn, modifying the oscillation frequency of the LC resonator. The shift in the oscillation frequency is used to characterize the nanoparticles and measure their magnetic susceptibility frequency profile. The spectrometer operates at multiple frequencies over a diverse range without using a reference sensor thereby effectively increasing its spatial multiplexing density.

Abstract: A chute assembly (10) to deliver product to a former (11) of a packaging assembly. The chute assembly (10) includes a chute (14) that converges downwardly. Located adjacent the chute (14) is a metal detector (21) having a transmitting and receiving coils (22) of different diameters. The receiving coils (22) being adapted to provide a signal when metal is detected.

Abstract: A control system for controlling a synchronous motor having a magnet in a rotor includes an inverter configured to output an AC current for driving the motor, a gate command generating unit configured to generate a gate command for controlling the inverter, a current detecting unit configured to detect the AC current output by the inverter, a magnetic pole position estimating unit configured to estimate a magnetic pole position based on the AC current detected by the current detecting unit and generate an estimation signal, a current command generating unit configured to generate a current command and an estimation command for controlling the inverter to output an AC current with a predetermined level, and a magnetic polarity determination unit configured to determine the polarity of the magnet based on the estimation signal.

Abstract: A magnetic-field detecting device includes a pair of magneto-sensors including respective magnetism sensing portions that sense magnetism, and respective coils sensing changes of magnetic fluxes in the magnetism sensing portions, and an elongate connecting member cooperating with the magnetism sensing portions to constitute a magnetic circuit. A magnetism sensing direction of the magnetism sensing portions coincides with a longitudinal direction of the connecting member to an extent that permits the coils to equally sense a magnetic field applied to the coils the connecting member being formed of a magnetic material having a relative magnetic permeability of at least 100, a magnetic material having a relative magnetic permeability which is at least 1/100 of that of a magnetic material of the magnetism sensing portions, or the same magnetic material as the magnetism sensing portions the magnetic-field sensor measuring the magnetism on the basis of a difference between outputs of the coils.

Abstract: A method for operating a metal detection system that comprises a balanced coil system. One embodiment of the method comprises: determining the phase and magnitude of related signals at least for a first metal contaminant for at least two transmitter frequencies and for at least two particle sizes of the first metal contaminant; determining the phase and magnitude of the related signal for a specific product for the at least two transmitter frequencies; comparing information established at least for the first metal contaminant and the information established for the product; determining a transmitter frequency with which signal components of smallest sized particles of the at least first metal contaminant differ sufficiently or most in phase and amplitude from the phase and amplitude of the product signal; and selecting the transmitter frequency for measuring the product. A metal detection apparatus adapted to operate according to an exemplary method is also provided.

Abstract: A planar magnetic field probe is provided. The planar magnetic field probe increases the sensitivity of magnetic field intensity detection by using a left multi-sensor loop and a right multi-sensor loop formed by a first patterned metal layer and a second patterned metal layer, and decreases the electric field noise coupling by surrounding the left multi-sensor loop and the right multi-sensor loop with a symmetrical shielding metal structure formed by a first patterned shielding metal layer, a second patterned shielding metal layer and a plurality of through vias.

Abstract: A detection system comprising a plurality of magnetic field generators and a plurality of magnetic field detectors located adjacent to a detection area, and a control system arranged to generate magnetic field using the generators, and, for each of the generators, to make measurements of the magnetic field generated using each of the detectors, and processing means arranged to process the measurements to generate a data set characterising the detection area.

Abstract: An electrical current sensor includes a first laminated body having a magnetic detection element disposed over a first substrate, a protective film formed over the first substrate and the magnetic detection element, and a coil formed over the protective film, and a second laminated body having a shield layer formed over a second substrate and which is formed by bonding the first laminated body and the second laminated body to each other with an adhesion layer interposed therebetween such that the magnetic detection element and the shield layer face each other.

Abstract: A fluxgate sensor has a driver coil, a signal coil, and a magnetic core that magnetically couples the driver coil and the signal coil. A magnetic field detector that can be positioned in a remote area is provided. The magnetic field detector is connected to a magnetic field generator positioned in the vicinity of the magnetic core by a transmission line, where the magnetic field of the magnetic field generator is superposed with the driver field.

Abstract: A system and method for measuring volumes and areas using electromagnetic induction techniques. A current is generated and fed into one of two coil assemblies to induce voltage into another coil assembly to provide accurate values for volume or area.

Abstract: A detecting device includes a reading coil configured to read a magnetic flux generated by a detecting coil for detecting a magnetic field of an electromagnetic wave output from an exciting coil according to the magnetic field. The detecting device further includes a Q-value measuring section configured to measure a Q-value of the detecting coil on a basis of a temporal transition of oscillation of a voltage obtained in the reading coil according to the magnetic flux generated by the detecting coil.

Abstract: A magnetic sensor device may include a magnetic sensor element structured to detect a magnetic property of a medium. The magnetic sensor element may include a sensor core having a body part and one or a plurality of protruded part(s) which is protruded from the body part, an exciting coil which is wound around the sensor core, and a detection coil which is wound around the sensor core. The body part and the protruded part of the sensor core forms an open magnetic path, and a stepped part is formed on a side face of at least one piece of the protruded part.

Abstract: The method for cancellation of low frequency noise in a magneto-resistive mixed sensor (1) comprising at least a superconducting loop with at least one constriction and at least one magneto-resistive element (6) comprises a set of measuring steps with at least one measuring step being conducted with the normal running of the mixed sensor and at least another measuring step being conducted whilst an additional super-current is temporarily injected in the at least one constriction of the at least one superconducting loop of the mixed sensor (1) up to a critical super-current of the constriction so that the result of the at least another measuring step is used as a reference level of the at least one magneto-resistive element (6).

Abstract: A wireless energy transfer system includes a foreign object debris detection system. The system includes at least one wireless energy transfer source configured to generate an oscillating magnetic field. The foreign object debris may be detected by at least one field gradiometer positioned in the oscillating magnetic field. The voltage of the at least one field gradiometer may be measured using readout circuitry and a feedback loop based on the readings from the gradiometers may be used to control the parameters of the wireless energy source.

Abstract: A current sensor includes a pair of magnetic balance sensors and a switching circuit. The magnetic balance sensors each include a magnetic sensor element and a feedback coil. The magnetic sensor element varies in characteristics due to an induction field caused by measurement current. The feedback coil is disposed near the magnetic sensor element and produces a canceling magnetic field canceling out the induction field. Each of the magnetic balance sensors outputs, as a sensor output, a value corresponding to current flowing through the feedback coil when a balanced state in which the induction field and the canceling magnetic field cancel each other out is reached after the feedback coil is energized. The switching circuit turns on/off one of the magnetic balance sensors.

Abstract: A sensor comprises a housing which defines a measuring side and a connection side, a coil (6) which is arranged in the housing (1) on the measuring side, and a cover (14) for closing the housing on the measuring side. The housing (1) consists of ferromagnetic material, in particular ferromagnetic steel. The coil (6) is positioned and fixed in the housing close to the cover (14) or directly on the cover (14).

Abstract: The present invention provides an axially symmetric vertical magnetic field component sensor system capable of intensifying vertical magnetic field components. The sensor system comprises an axially symmetrical magnetic substance comprising a circular, oval or polygonal shaped flat disk and a protrusion formed on a center of the flat disk. The sensor system is used for a response system having an IC wound by a coil which generates signals and the sensor system is mounted on a metal surface or buried in a hollow formed on the metal surface.

Abstract: A vibration and condition monitoring system with true digital signal processing based design, with very limited analog based general signal conditioning and integrated specific sensor conditioning and sensor power supply options. The device supports direct connection of eddy current probe systems to the module, due to a built-in driver and linearization functionality. Linearization and compensation of a specific eddy current probe/cable system is done by measuring its far/infinite gap response. This response is then according to the invention recalculated into a linearization curve/transfer function. Specific sensor signal conditioning is not dependent on hardware, but only on embedded software (firmware). There is full sensor input support in an I.S. environment. Not only the common sensor input types from accelerometer, velocity sensor or eddy current probe system for both vibration and/or speed measurements.

Abstract: A system for and method of determining and compensating for the effect of a field influencing object on a field sensor, preferably a coil, that is within a navigational domain. The navigational domain contains navigational magnetic energy and disturbing magnetic energy, and the field influencing object produces the disturbing magnetic energy in response to the navigational magnetic energy. The correction system includes a first transmitter for projecting into the navigational domain field energy in a first waveform sufficient to induce a first signal value in the sensing coil. The system also includes a second transmitter for projecting into the navigational domain field energy in a second waveform sufficient to induce a second signal value in the sensing coil. The system further includes a signal processor for receiving the first signal value and for receiving the second signal value to determine the effect of the electrically conductive object on the field sensor.

Abstract: In accordance with the present disclosure, a system and a method are disclosed for measuring a time varying magnetic field. In one aspect, a system comprises a plurality of induction coils arranged to measure the time varying magnetic field using at least one voltage induced in at least one of the induction coils in the plurality of induction coils, a plurality of snubber circuits connected to the plurality of induction coils, each of the snubber circuits of the plurality of snubber circuits arranged to suppress a resonance of a respective one of the induction coils of the plurality of induction coils, and a summing circuit connected to each of the snubber circuits of the plurality of snubber circuits, the summing circuit arranged to sum voltages induced in each of the induction coils in the plurality of induction coils.

Abstract: A receiver and tracking system for identifying a location of a magnetic field source. In a preferred embodiment a plurality of tri-axial antennas are positioned at three distinct points on a receiver frame. Each antenna detects a magnetic field from a source and a processor is used to determine a location of the source relative to the frame using the antenna signals. Each tri-axial antenna comprises three windings in each of three channels defined by a support structure. The windings each define an aperture area. The windings have substantially identical aperture areas and have a common center point. The receiver may to display to the operator the relative location of the field source or may direct the operator to a spot directly above the field source.

Abstract: A method for operating a metal detection system that comprises a balanced coil system. One embodiment of the method comprises: determining the phase and magnitude of related signals at least for a first metal contaminant for at least two transmitter frequencies and for at least two particle sizes of the first metal contaminant; determining the phase and magnitude of the related signal for a specific product for the at least two transmitter frequencies; comparing information established at least for the first metal contaminant and the information established for the product; determining a transmitter frequency with which signal components of smallest sized particles of the at least first metal contaminant differ sufficiently or most in phase and amplitude from the phase and amplitude of the product signal; and selecting the transmitter frequency for measuring the product. A metal detection apparatus adapted to operate according to an exemplary method is also provided.

Abstract: A device includes a housing, a first magnetic field sensor, a second magnetic field sensor, and a control module. The housing is configured to be implanted in a patient. The first magnetic field sensor is located at a first location within the housing and is configured to measure a first strength of a magnetic field at the first location. The second magnetic field sensor is located at a second location within the housing and is configured to measure a second strength of the magnetic field at the second location. The control module is configured to identify a source of the magnetic field based on the first and second strengths.

Abstract: The invention relates to a method and arrangement for the contactless determination of conductivity-influencing properties and their spatial distribution over the entire cross section of an electrically conductive substance moving in a primary magnetic field (B). The substance may be a liquid or a solid. A simultaneous measurement of a number of mechanical state parameters of the magnetic system is performed (three-dimensional components of the force and the torque), said parameters being variable by the effect of a secondary field on the magnetic system, the secondary field being produced on the basis of eddy currents induced in the substance by the primary field (B). To determine the spatial distribution of the property that is sought, the primary field is changed in intensity or form a number of times and a measurement of the state parameters is carried out for each change.

Abstract: A magnetic sensor array includes a first three-dimensional magnetic sensor secured to a substrate in a central location of the substrate. A number of second three-dimensional magnetic sensors are secured to the substrate at a first distance from the first magnetic sensor. Additionally, a number of one-dimensional magnetic sensors are secured to the substrate at a second distance from the first magnetic sensor greater than the first distance. Additional magnetic sensors of any dimension may also be included. The magnetic field sensitivity of the first and second three-dimensional magnetic sensors may be less than the magnetic field sensitivity of the one-dimensional magnetic sensors. The sensing range of the first and second three-dimensional magnetic sensors may be greater than the sensing range of the one-dimensional magnetic sensors. The magnetic sensor array may also include a processing circuit coupled to the magnetic sensors.

Abstract: A device to test the good working order of a magnetic field generator, and namely a demining coil, such device comprising at least one evaluation means for the magnetic field coupled with at least one display means, device wherein said evaluation means comprise at least one wound coil able to be positioned so that the lines of the magnetic field pass through it, said wound coil linked to evaluation electronics powered by said wound coil itself.

Abstract: The present invention provides a fluxgate magnetic sensor element which includes: a substrate; an exciting pattern which is disposed on the substrate to generate a magnetic field; a magnetic thin film pattern for detection which is disposed adjacent to the exciting pattern; and a detection coil pattern which is disposed adjacent to the magnetic thin film pattern for detection. In the magnetic sensor element, the exciting pattern, the magnetic thin film pattern for detection, and the detection coil pattern are formed on the substrate. Therefore, the magnetic sensor element can be formed into a flat shape. Moreover, since the length of the generated magnetic field is short in a long-axis direction, the size and thickness of the element itself can be reduced.

Abstract: A measuring apparatus includes a measuring body and a probe device. The probe device includes a dome-shaped metal shield, a probe, and a cable. The metal shield defines an opening in a bottom of the shield. The probe is mounted inside the metal shield. A first end of the cable is connected to the probe, and a second end of the cable passes through a top of the metal shield and then is connected to the measuring body.

Abstract: A Barkhausen noise inspection device of the present invention includes a detecting head (1), made up of an exciting coil (2) for magnetizing an object (30) to be inspected, a detecting coil (3) for detecting Barkhausen noises generated from the object (30) having been magnetized, and an electric power source (12) for supplying to the exciting coil (2) an alternating current necessary to generate an alternating magnetic field necessary for magnetization. A magnetic flux detecting sensor (6) is provided for detecting the magnitude of a magnetic flux used to excite the object (30). Also, an electric current control module (11) is provided for controlling the alternating current of the electric power source (12) on the basis of the magnitude of the magnetic flux, detected by the magnetic flux detecting sensor (6), to thereby maintain the magnitude of the magnetic flux, used to excite the object (30), at a constant value.