A microcontroller-based quasi-balanced bridge for the measurement of L, C and R
TL;DR: In this article, a microcontroller-based quasi-balanced bridge for the measurement of parameters of an inductor or a capacitor is described, where the unknown element (inductor or capacitor) in series with a resistor forms one-half of an ac bridge, while a multiplying digital-to-analog converter (MDAC) serves as the other half.
Abstract: A microcontroller-based quasi-balanced bridge for the measurement of parameters of an inductor or a capacitor is described. The unknown element (inductor or capacitor) in series with a resistor forms one-half of an ac bridge, while a multiplying digital-to-analog converter (MDAC) serves as the other half. The bridge is brought into two independent quasi-balanced conditions in succession by the microcontroller through the MDAC. The parameters of the unknown element are shown to be functions of the settings of the MDAC at the two quasi balanced conditions. The relevant expressions for these parameters are evaluated by the microcontroller and the results displayed in appropriate display fields. The proposed scheme was implemented using an Intel 8751 microcontroller and tested. The readings obtained on the prototype were compared to those obtained with a commercial LCR meter. Employing an MDAC of basic accuracy /spl plusmn/0.2%, over the frequency range of 100-1000 Hz, an overall uncertainty in measurement of /spl plusmn/0.7% for the prototype was achieved.
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11 May 2015
TL;DR: This paper presents a simple digitizer suitable for differential variable inductive/reluctance sensors that uses a ratio-metric approach in the computation and hence the output is less sensitive to variation in the parameters.
Abstract: This paper presents a simple digitizer suitable for differential variable inductive/reluctance sensors. The proposed scheme uses two digital I/O pins, a counter and a comparator of a microcontroller and obtains a digital output directly proportional to the measurand which is sensed using a differential variable inductive/reluctance sensor possessing either a linear or an inverse transfer characteristic. The scheme uses a ratio-metric approach in the computation and hence the output is less sensitive to variation in the parameters such as excitation voltage, reference voltage, offset of the comparator, etc. A prototype of the proposed system has been built and tested using standard variable inductors that emulated a differential inductive sensor following an inverse characteristic. The output recorded was linear across the full range and worst-case error noted was less than 0.3 %. For the prototype developed, the time taken to complete a measurement was 200 µs. The prototype digitizer has been interfaced with a commercially available LVDT and tested. The worst-case error observed in this test was 0.77%. Also, the same digitizer has been employed to get a digital readout from a differential variable reluctance based displacement sensor. The worst-case error was less than 0.83%. The test results establish the efficacy of, the simple and cost effective, scheme developed.
27 citations
Cites background from "A microcontroller-based quasi-balan..."
...The quazi-balanced [9] and modified Maxwell-Wien bridge [10] schemes are examples of such improvements....
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TL;DR: In this paper, a novel method of dielectric loss factor measuring has been described based on a quasi-balanced method for the capacitance measurement, which is based on an artificial neural network.
Abstract: Abstract A novel method of dielectric loss factor measuring has been described. It is based on a quasi-balanced method for the capacitance measurement. These AC circuits allow to measure only one component of the impedance. However, after analyzing a quasi-balanced circuit's processing equation, it is possible to derive a novel method of dielectric loss factor measuring. Dielectric loss factor can be calculated after detuning the circuit from its quasi-equilibrium state. There are two possible ways of measuring the dielectric loss factor. In the first, the quasi-balancing of the circuit is necessary. However, it is possible to measure capacitance of an object under test. In the second method, the capacitance cannot be measured. Use of an artificial neural network minimizes errors of the loss factor determining. Simulations showed that the appropriate choice of the range of the detuning can minimize errors as well.
13 citations
Cites background from "A microcontroller-based quasi-balan..."
...[1] is a representative of a specific group of measuring circuits, the so-called quasi-balanced circuits [2-10]....
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TL;DR: In this paper, the authors present the synthesis and implementation of a non-bridge quasi-balanced circuit designed to measure the dielectric loss factor, based on the well-known bridge circuit.
Abstract: This study presents the synthesis and implementation of non-bridge quasi-balanced circuit designed to measure the dielectric loss factor Synthesis is performed on the basis of the well-known bridge circuit The equations of detected signal have been derived and their processing equations have been developed using a general model of a quasi-balanced circuit Then, a structural diagram describing the processing of signals in the two states of quasi-equilibrium has been derived An example of a virtual implementation of the derived circuit has been presented
11 citations
TL;DR: In this paper, the authors presented equations for the calculation of the self and mutual inductances of the modular toroidal coil (MTC) applicable to Tokamak reactors, which is composed of several solenoidal coils connected in series and distributed in the toroidal and symmetrical forms.
Abstract: In this paper, equations for the calculation of the self- and mutual inductances of the modular toroidal coil (MTC) applicable to Tokamak reactors are presented. The MTC is composed of several solenoidal coils (SCs) connected in series and distributed in the toroidal and symmetrical forms. These equations are based on Biot-Savart's and Neumann's equations, respectively. The numerical analysis of the integrations resulting from these equations is solved using the extended three-point Gaussian algorithm. Comparing the results obtained from the numerical simulation with the experimental and the empirical results confirms the presented equations. Furthermore, the comparison of the behavior of these inductances, when the geometrical parameters of the MTC are changed, with the experimental results shows an error of less than 0.5%. The behavior of the inductance of the coil indicates that the optimum structure of this coil, with the stored magnetic energy as the optimization function, is obtained when the SCs are located on the toroidal planes.
7 citations
Cites background from "A microcontroller-based quasi-balan..."
...With respect to the fact that explaining self- and mutual inductance measurement techniques [25]–[27] and the comparison of the errors obtained Fig....
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References
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TL;DR: In this article, phase sensitive detection is formalized in order that its operation can be understood and its practical use optimized, and the theory explains how narrow bandwidth amplification is achieved in order to reduce the noise content of a measurand and how the process can be considered simply as a multiplier followed by a low-pass filter.
Abstract: Phase sensitive detection is formalized in order that its operation can be understood and its practical use optimized. The theory explains how narrow bandwidth amplification is achieved in order to reduce the noise content of a measurand and how the process can be considered simply as a multiplier followed by a low-pass filter. The responses to various excitation and measurand forms are derived for signals ranging from the simple sinusoids to the more complicated signals produced when modulating interference fringes and stabilized laser cavities.
150 citations
Book•
13 Sep 1996
TL;DR: In this paper, the authors present a comprehensive coverage of transducers, but a basic knowledge of electronic circuitry is assumed, such as Thevenin's and Norton's theorems, and a working knowledge of circuit theory is assumed.
Abstract: Nearly one-third of the book relates to error theory and its applications to physical measurements. Some of the topics, such as the measurement of electrical potential difference and electrical current are of historical importance. Elementary topics like the treatment of errors and complex topics like noise are dealt with at the same mathematical level. Although Thevenin's and Norton's theorems are mentioned, a working knowledge of circuit theory is assumed. Although transfer functions are mentioned, feedback stability and transient response of systems are discussed at a practical level. A comprehensive coverage of transducers is included, but a basic knowledge of electronic circuitry is assumed. Practical aspects of signal conditioning, D/A, A/D and displays are well presented. Electronic measuring instruments, ranging from digital voltmeters and oscilloscopes to computer controlled data acquisition systems, are all well described in a few pages. For a given space allocation a less ambitious coverage would be more effective. For the physics oriented reader in both industry and academia, the book could still be useful as a source of technical information. Its use as a text for undergraduate courses is doubtful, although it should be a ready reference for laboratory work. A de Sa
61 citations
TL;DR: In this article, a digital method for the measurement of real and imaginary parts of the impedance (rectangular-form), as well as its magnitude and phase (polar-form) is described.
Abstract: A digital method for the measurement of the real and imaginary parts of the impedance (rectangular-form), as well as its magnitude and phase (polar-form) is described It depends on using a novel hybrid processor that gives digital numbers that are proportional to the imaginary and real parts of the impedance, besides the magnitude and phase A circuit for indicating whether the impedance is capacitive or inductive is also given This method could also be used for admittance measurement and for the determination of the inductance or capacitance of any circuit The basic accuracy of the system is about 02% >
16 citations
TL;DR: In this article, a digital measurement system is described which measures the voltages across a voltage divider consisting of a reference resistor and the unknown impedance, so that their magnitude and phase are digitally determined.
Abstract: A digital measurement system is described which measures the voltages across a voltage divider consisting of a reference resistor and the unknown impedance. The voltages across reference and unknown are converted so that their magnitude and phase are digitally determined.
13 citations