Yazar "Erismis, Mehmet Akif" seçeneğine göre listele

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    Analysis and design of a transimpedance amplifier based front-end circuit for capacitance measurements
    (Springer Int Publ Ag, 2020) Demirtas, Mehmet; Erismis, Mehmet Akif; Gunes, Salih
    In this study, transimpedance amplifier based front-end circuits which can be employed to measure small capacitances were designed, analyzed and simulated using analog electronic circuit simulator. The front-end circuit converts the current flowing through the measured capacitance into a modulated voltage value which contains information regarding the desired capacitance. The frequency-domain, time-domain, stability and noise analyzes were carried out numerically and in simulation environment using a circuit simulator. The analytical, numerical and simulation results can be used to design optimized, precise and stable transimpedance amplifiers with low-noise value. The measured capacitance value was 10 pF which is low enough to simulate various real-world applications. Three commercially available, off-the-shelf operational amplifiers with different peripheral passive components were employed for computer based analysis. The designed transimpedance amplifiers are suitable to connect with capacitance extraction circuits which use analog or digital demodulation techniques.
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    The Effect of Rotor Plates on Capacitive Measurement in Capacitive Encoders
    (IEEE, 2020) Yavsan, Emrehan; Karali, Mehmet; Gokce, Baris; Erismis, Mehmet Akif
    The moving plates of the capacitive encoders are called rotors and the fixed plates are called stators. In this study, the effects of the rotor plates on capacitive measurement for capacitive encoders are analyzed. Encoders are used in angular position measurement. They can be preferred especially in most applications where rotational motion occurs in the robotic application areas. The application areas of the encoders can be further extended with the capacitive encoder technology. The capacitive encoder technology is based on measuring the capacitances between the encoder plates. As the capacitances vary depending on the overlapping areas of the encoder plates, the shapes and the patterns of the encoder plates directly affect the capacitive measurement. Therefore, the capacitive encoder plate selections must be made correctly. There are very few studies on the selection of the capacitive encoder plates. It is seen that the current studies generally continue on a similar type rotor patterns. Various rotor plates are proposed in this study for the capacitive encoder that we are in the development process. After the rotor patterns are expressed mathematically and the capacitive encoders using rotors with these patterns are compared. The comparison process was made by calculating the equivalent capacitance between the proposed capacitive encoder plates. The effects of rotors with different materials and patterns on the capacitive measurement were investigated. Thus, a contribution was made to the effective development of similar capacitive sensors.
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    A Lossy Capacitance Measurement Circuit Based on Analog Lock-in Detection
    (Kaunas Univ Technology, 2020) Demirtas, Mehmet; Erismis, Mehmet Akif; Gunes, Salih
    This paper presents a lossy capacitance measuring circuit which is based on analog lock-in detection technique. Lossy capacitance can be modelled as a pure capacitor connected in parallel with a resistor. The measurement circuit mechanism consists of an excitation signal to drive the lossy capacitance, a transimpedance amplifier to produce a voltage, and a lock-in detection circuit to extract lossy values of capacitance. The lock-in detector multiplies its input with a square wave using switches and filters out high frequencies to give a DC output that is actually in proportional to the measured values. A field programmable gate array is employed to generate direct digital synthesis based sinusoidal excitation signal to generate reference signals required for demodulation and to measure the output of lock-in detection. The phase shift between the excitation signal and reference signals is controlled accurately in digital domain. Thus, due to the phase mismatch, errors are properly reduced. Also, analog phase shifter and analog switch-driving circuits are no longer required. Three different lossy capacitors realized using discrete components are simulated and tested. The maximum relative error is 1.62 % for the resistance measurement and 6.38 % for the capacitance measurement.
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    A New Discrete Analog Circuit Solution for Capacitive Rotary Encoders
    (IEEE-Inst Electrical Electronics Engineers Inc, 2022) Kara, Muhammet Rojhat; Yavsan, Emrehan; Karali, Mehmet; Erismis, Mehmet Akif
    In the time of global chip crisis, it is clear that alternative electronic solutions are necessary; particularly for capacitive rotary encoders, or similar capacitive sensors where demodulation techniques are extensively used. In this work, a discrete analog switch based circuit solution is proposed for the capacitive rotary encoders for the first time in the literature to the best of our knowledge. A 3-layer uniquely designed capacitive encoder prototype is used as a capacitive sensor. The analog switch with OPAMP based demodulation configuration designed for this work is both cheaper and it works at higher frequencies than the analog multiplier configuration. Also, unlike ASIC, it does not require high-tech for production. With the established test setup; noise, smallest perceptible capacitance, nonlinearity and temperature analyses of the circuit were made and competing resultswere achieved. The noise levels in terms of degree and voltage are measured as 0.0063 degrees and 36.62 mu V root Hz; respectively. Minimum measurable capacitance achieved with the discrete analog circuit is 2.54 aF root Hz. Nonlinearity was found to be 0.29% which is highly correlated with the mechanical misalignments of the capacitive encoder. Although this particular study is carried out on capacitive encoders, the proposed circuit solution can be used for similar types of sensors.
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    A novel high resolution miniaturized capacitive rotary encoder
    (Elsevier Science Sa, 2021) Yavsan, Emrehan; Kara, Muhammet Rojhat; Karali, Mehmet; Gokce, Baris; Erismis, Mehmet Akif
    In this paper, design and prototyping of a novel, high resolution, and low-cost capacitive encoder were presented. Detailed analysis showed that the number of poles on the rotor should be as high as possible to keep the gain high and to reduce the non-linearity. Moreover, contrary to the common intuition, inter electrode gap is found to have an optimum non-zero value, corresponding to a particular number of poles, in order to maximize the gain. However, increasing number of poles brings practical problems due to manufacturing limits and digital electronic frequency load. As the electronics, micro-controller based digital signal processing is used to keep the cost as low as possible. With miniaturizing the encoder geometry as a design target, the number of plates were increased to three to increase the capacitances. One prototype, which is around 3 cm in diameter could be successfully mounted to an industry oriented DC motor and tested. The tests of this miniaturized encoder showed non-linearity error of 0.12% and resolution of 0.02 degrees. One source of the non-linearity error is the DC motor itself, and we believe that with a better setup, the error could be measured to be even better. (C) 2021 Elsevier B.V. All rights reserved.
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    The simulation and production of glow plugs based on thermal modeling
    (Tubitak Scientific & Technological Research Council Turkey, 2015) Endiz, Mustafa Sacid; Ozcan, Muciz; Erismis, Mehmet Akif; Yagci, Mustafa; Gunay, Hidayet
    In this work, we present the thermal behavior of a glow plug examined with thermal impedance modeling. The circuit model is based on the analogy of thermal and electrical domains and expresses the glow plug used in diesel engines to preheat the air-diesel fuel mixture. In this study, the circuit design, implementation, and simulation of a glow plug for diesel engines are illustrated. In order to verify this thermal model, 2 different glow plugs are produced. The test results of the glow plugs produced in this study show complete agreement with the simulation results. It is thought that this circuit-based model will provide fast and reliable simulations and will be beneficial in the industry for addressing different glow plug needs.