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Class AB audio power amplifier for home use
Vaško, Dominik ; Theumer, Radek (referee) ; Brančík, Lubomír (advisor)
This bachelor's thesis deals with the design of a classic class AB audio power amplifier with a minimum power of 2x25W intended for home use and the design of a suitable power supply unit. The final stage of the amplifier is realized by an integrated circuit LM3886, which is supplemented by the design of a correction preamplifier and an excitation indicator. The correction preamplifier is implemented using the LM1036 integrated circuit, the excitation indicator, in turn, by the LM3915 integrated circuit. The results of the work are designs for the schematic connections of the final stage, correction preamplifier and excitation indicator, as well as designs and implemented printed circuit boards and the resulting device with measured characteristics.
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A device for demonstrating the function of oscillators with fractional-order elements
Walach, Vít ; Šotner, Roman (referee) ; Brančík, Lubomír (advisor)
This bacherol thesis deals with fractional-order elements and it’s application for RC oscillators. The aim is to carry out simulations of two different oscillators using fractional-order capacitors and then design and manufacture a device demonstrating the function of the selected oscillator. Several methods of approximation of constant phase elements are described in this work, including their circuit realization for Foster and Cauer structures. The selected RC oscillators are modeled numerically in Matlab, as well as simulated in Pspice, so that the results of both simulations can be compared. The presented oscillator with two constant phase elements is implemented on a printed circuit board. At the end of the work, the results of experimental measurements are presented in comparison with simulations.
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Frequency filters with fractal two-terminal elements
Egorov, Gleb ; Brančík, Lubomír (referee) ; Petržela, Jiří (advisor)
This thesis focuses on the use of fractal components in the design of frequency filters and phase shifters. The primary task was to calculate the characteristics of fractal capacitors with mathematical series of 0.75, 0.5, and 0.25. Subsequently, their functionality was verified using the Orcad Spice circuit simulator and in practical applications. During the work, fractal components were not only theoretically modeled but were also implemented and tested in various configurations of electronic circuits, allowing for a thorough examination of their properties and effectiveness.
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Extraction of impedance model circuit parameters and its emulation
Semenov, Dmitrii ; Brančík, Lubomír (referee) ; Šotner, Roman (advisor)
V této bakalářské práci byly představeny dva optimalizační algoritmy v MATLABu: první je pro extrahování nul/pólů, jejích počtu a frekvence celočíselných kořenu přenosových funkcí s komplexním kmitočtem "s". Tento algoritmus byl ověřen na aktivních a pasivních filtrech typů Pásmová Propust (PP), Pásmová Zadrž (PZ) a bilineárních sekcích. Druhý algoritmus aproximuje fraktální přenosové charakteristiky s určitým (nastavitelným uživatelem) počtem nul/pólů pomocí optimalizace "roje včel". Tento algoritmus byl ověřen na vzorku bioimpedance, jako je pomerančová šťáva. Vlastní testovací deska plošného spoje (DPS) emulátoru, která je založená na vlastních Operačních Transkonduktančních Zesilovačích (OTA), které jsou vyrobené v procesu I3T25 350nm, byla vyvinuta pro emulaci charakteristik bioimpedance s parametry extrahovanými pomocí algoritmu. Výsledky emulace byly poté porovnány z hlediska přesnosti s komerčním softwarem NOVA Metrohm pro elektrochemickou analýzu.
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Stereo audio amplifier with equalizer and remote control
Lipenský, Lukáš ; Kratochvíl, Tomáš (referee) ; Brančík, Lubomír (advisor)
The bachelor thesis deals with the possibilities of realization, design and construction of a stereo audio amplifier with a pre-assigned ten band graphic equalizer. The amplifier operates in class D and has an output power of 2x140 W into a 4 load, speakers. The signal adjusted by the equalizer can be amplified in the amplifier and reproduced by the speakers or transmitted to a remote receiver, such as headphones, via a bluetooth module. The equalizer has 10 bands for adjusting the frequency characteristics of the signal and the signal level (volume). The settings of the individual, predefined characteristics according to the type of music you are currently listening to can be selected using the IR remote control.
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Numerical Modeling of Periodical Structures
Nešpor, Dušan ; Bartušek, Karel (referee) ; Brančík, Lubomír (referee) ; Fiala, Pavel (advisor)
The thesis discusses the dynamic electromagnetic field on periodic structures. The author focuses on three principal types of resonant structures, considering their application possibilities. In general, these types can be individually defined as follows: materials exhibiting a negative refractive index of the incident electromagnetic wave; structures with gradual changes in impedance, characterised by their usability as reflectionless surfaces; and periodic structures able to conveniently shape the magnetic field distribution. Materials of the third group within the above-shown short list facilitate the fabrication of magnetoinductive lenses for nuclear magnetic resonance. The presented analysis of the properties of periodic resonant structures is mainly based on numerical models utilising the finite element method, and this approach is combined with both the derivation of the corresponding analytical relations and an experimental measurement of the non-radiating component of the electromagnetic field. The thesis includes a physical description of the basic elements of periodic resonant structures. Physical properties of the elements were examined in detail via numerical analysis. In the course of the research, the data acquired through this analysis and the related experimental measurement enabled the author to propose a method for optimising the most widely used resonant structures. Moreover, several new versions of resonant elements, structures, and fabrication techniques were also designed. The results obtained from the numerical analyses carried out to examine the central physical properties of the fabricated structure samples were all verified via the designed method for measuring the non-radiating component of the magnetic field.
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Optimizing Image Reconstruction in Electrical Impedance Tomography
Dušek, Jan ; Brančík, Lubomír (referee) ; Sikora, inž Jan (referee) ; Mikulka, Jan (advisor)
Tato disertační práce pojednává o optimalizaci algoritmů pro rekonstrukci obrazu neznámé měrné vodivosti z měřených dat pořízených elektrickou impedanční tomografií. Danou problematiku zde věcně vymezuje několik různých prvků, zejména pak stručný matematický popis dopředné a inverzní úlohy řešené různými přístupy, metodika měření a pořizování dat pro rekonstrukci a přehled dostupných numerických nástrojů. Uvedenou charakteristiku rozšiřuje rozbor optimalizací parametrů modelu ovlivňujících přesnost rekonstrukce, způsoby paralelního zpracování algoritmů a souhrn dostupných zařízení pro měření tomografických dat. Na základě získaných poznatků byla navržena optimalizace parametrů matematického modelu, která umožňuje jeho velmi přesný návrh dle měřených dat. V této souvislosti dochází ke snížení nejistoty rekonstrukce rozložení konduktivity. Pro zefektivnění procesu získávání dat bylo navrženo zařízení k automatizaci tomografie s důrazem na cenovou dostupnost a snížení nejistoty měření. V oblasti tvorby numerického modelu byly dále zkoumány možnosti užití otevřených a uzavřených domén pro různé metody regularizace a hrubost sítě, a to s ohledem na velikost chyby rekonstruované konduktivity a výpočetní náročnost. Součástí práce je také paralelizace subalgoritmů rekonstrukce s využitím vícejádrové grafické karty. Předložené výsledky mají přímý vliv na snížení nejistoty rekonstrukce (optimalizací počáteční hodnoty konduktivity, rozmístění elektrod a tvarové deformace domény, regularizačních metod a typu domén) a urychlení výpočtů paralelizací algoritmů, přičemž výzkum byl podpořen vlastním návrhem jednotky pro automatizaci tomografie.
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Audio pre-amplifier for two satellites and subwoofer
Štaud, Stanislav ; Brančík, Lubomír (referee) ; Kratochvíl, Tomáš (advisor)
The aim of this thesis was to design, simulate and construction audio pre-amplifier for two satellites and subwoofer and monolithic amplifier for subwoofer in the class AB. Audio pre-amplifier provides bass, treble and switch loudness volume control. It includes subsonic filter and active crossovers Sallen-Key with approximation Linkwitz-Riley. There are low noise operating amplifiers LM833 and TL081 at the place of active amplifiers with very low distortion. End-amplifier can delivers power 50 W to 4 ohms. Of consists delayed switch speaker and supports security against direct voltage on the output of amplifier.
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Optimization of Basic Magnetic Field Homogeneity in MR Tomography
Hadinec, Michal ; Brančík, Lubomír (referee) ; Frollo, Ivan (referee) ; Bartušek, Karel (advisor)
This thesis is concerned with problems of measuring and mapping of magnetic field in MR tomograph, for purpose of magnetic flux density homogeneity optimization. Attention is paid to mapping techniques on rotary symmetric volume and to ways of magnetic fields optimization with utilization of passive and active correction systems. Theoretical analysis of magnetic field decomposition with utilization of spherical harmonics and numerical decomposition is made. Mapping and approximation techniques of basic magnetic field are verified by experiments in the laboratory at the Institute of Scientific Instruments AS CR in Brno.
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Design of switching low-frequency power amplifier
Janáč, Josef ; Kratochvíl, Tomáš (referee) ; Brančík, Lubomír (advisor)
This bachelor project maps out switching technologies used in LF power electronics and gained information was consequentially used to design switching lf power amplifier as independent unit. Content of design is LF power amplified level, working on switching technology principle. Correction pre-amplifier with possibility of adjusting volume, balance h/l frequency and switching power supply is content as well too. Next part of project is familiarization s design program Eagle and optimizing program for switching power supply PXLS expert and creating constrictive basis for complete device. Last part of project is basically activation all functional part of device in one unit. Than measurement basic parameters on created functional device, graphical elaborating measurement-gained values and confrontation with catalog values. Conclusion of this project is evaluation achieved results in compare with supposed result of project.
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