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  • Compensation of additive temperature error of the Hall transducer

    In the article we discuss temperature errors caused by non-stationary thermal processes in a thin-film Hall transducer. When solving the heat conduction equation we show the significant influence of effects of Peltier and Seebeck on the Hall voltage measurement results in the current switching mode. A new twenty-step switching currents algorithm for the Hall transducer is proposed. In this algorithm the additional voltages are measured at the absence of current through the transducer. From the additional voltages we estimate the contribution of the temperature drift. It was experimentally shown that for the PHE602117 converter the additive temperature error decreases by 30 times in comparison with the four-step algorithm while reducing performance by 20%.

    Keywords: Hall transducer, additive error, Peltier effect, non-stationary processes, thermo-emf., magnetic measurements, current switching

  • Reciprocal relations for nonlinear magnetoactive plasma-like media

    In the paper the Vlasov equation solution is considered for a case of stationary, homogeneous, isotropic and weakly nonlinear magnetoactive plasma-like media by successive approximations technique. An expression for the quasi-linear conductivity is obtained, which at low magnetic field ceases to depend on the electric field. It is shown that the quasi-linear conductivity matrix is symmetric, and its elements satisfy the classical reciprocal relations. The obtained relations can be applied in the design of magnetic microelectronics devices, for example, to improve the metrological characteristics of the digital Hall magnetometer.

    Keywords: reciprocal relations, nonlinearity, plasma-like media, kinetic coefficients, quasi-linear conductivity

  • The parametric method of determining a phase difference of quasi-harmonic signals

    The method of digital parametric measurement of the phase shift of signals with slowly varying amplitudes of the same slowly varying instantaneous frequencies was proposed. The numerical simulations and experiments on the developed hardware and software system were carried out. The error of measurement the phase difference of harmonic signals in the experiments were not more than  0,00001 radian. The method can be used in applications where the measured value is expressed in terms of the phase difference of quasi-harmonic signals.

    Keywords: quasi-harmonic signal, phase shift, real time measurements, hardware and software system

  • The hardware-software system for parametric analysis of signals in the problems of technical diagnostics

    This paper describes a hardware-based and software system parametric estimation of signals. It`s experimental accuracy was achieved measuring the phase difference between the two quasi-harmonic signals at 10 μrad.  

    Keywords: parametric analysis, technical diagnostics, the phase difference

  • Digital voltammograph

    A compact digital voltammograph for electrochemical analysis of aqueous solutions was created. Device’s construction and drawings of the electrochemical cell for the studying of small amounts of fluids are described. Electronic circuits are assembled on modern high-precision components. The device implemented using cyclic, normal pulse and differential pulse voltammetry. Experiments were carried out with solutions of copper ions and hydrogen peroxide to test operability and characteristics of the voltammograph. All implemented methods gave reproducible results that are consistent with the theory. Typical results of the experiments with solutions of copper ions are shown.

    Keywords: voltammetry, voltammograph, voltammogram, electrochemical cell, analysis of solutions

  • Digital proton magnetometer to measure the geomagnetic field

    Digital compact proton magnetometer was created for measure the geomagnetic fields, including the fields of high heterogeneity. We described design of the instrument and its principles of operation. This device is using implemented digital filtering techniques and Prony method to determine the frequency of the desired signal. The experiments were made in the fields of high heterogeneity and demonstrated the possibility of precise measurements in the fields with a gradient of up to 8 mT / m. The device can be used as a metal detector, as well as for magnetic prospecting, geological studies, etc.

    Keywords: nuclear magnetic resonance, free precession, proton magnetometer, geomagnetic field, digital filtering, Prony method

  • Dynamic cancelation of additive error of precision analog-to-digital converter

    Analog-to-digital converter, with modulation, amplification and demodulation of the input signal is carried out. To compensate the additional error of voltage conversion, concerned with temperature instability, used dynamic cancellation technique, based on the correlation between offset voltage and modulator temperature fluctuation. ADC with response time 0.85 s performs the threshold of sensitivity 1 nV; 8,5 s - 0,31 nV, 85 s - 0.13 nV, 850 s - 0.1 nV, respectively, in the full-scale range 400 mV. Estimation of offset voltage temperature drift is 40 pV / ºC, time drift - 100 pV / h.

    Keywords: analog-to-digital converter, ADC, error cancellation.

  • Flaw detection of a steel wire method of tensor magnetic topology

    `Described is the methodology of studying of topology of tensor quantity of magnetic field of leakage of natural defects in the natural geomagnetic field magnetization, which is the base for realization of digital Hall defect scope. Using this set it was managed to register the defects with the peculiar size of 15 microns in steel wire, which is used for reeling of butter spring of trucks.

    Keywords: non-destructive testing, Hall-effect sensor, magnetic tomography.