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Meaurement process automatization of deviations and stability of oscilators
Čermák, Jan ; Nováková Zachovalová, Věra (referee) ; Havlíková, Marie (advisor)
This Master´s thesis on a topic ,,Meaurement process automatization of deviations and stability of oscilators‘‘ describes methods for measuring the difference of time scales. Using this method, calculates the parameters of the oscillator, which is also describes in this work. Parameters of the oscillator means inning and stability. Describes is the procedure for calculating the uncertainties and their presentation in the final calibration sheet. This Master´s thesis also describes the practical measurement with this method in the Czech metrology institute in Brno. Measurement of the parameters of oscillator by the method of measurement of the difference of time scales is carried out automatically by computer. This Master´s thesis deals with the creation and development of new software and thus the automation of the entire task.
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Application possibilities of controllable current amplifier
Bradáč, Josef ; Koton, Jaroslav (referee) ; Jeřábek, Jan (advisor)
This thesis deals with the application using digitally controlled current amplifiers DACA (Digitally Adjustable Current Amplifer), which was developed at the Department of Telecommunications FEEC in cooperation with ON Semiconductor in 2010. In introduction is decribed the topic of active filters and oscillators. Farther active current components, besides DACA are described current conveyor UCC (Universal Current Conveyor), current amplifier DO-CF (Dual-Output Current Follower), MO-CF (Multiple-Output Current Follower) and FD-CF (Fully Diferential Current Follower) and operational transconductant amplifier BOTA (Balanced-Output Operational Transconductance Amplifer) and MOTA (Multiple-Output Operational Transconductance Amplifier). The following is a compilation of theories circuits using signal flow graphs, which are designed using a simulated filter circuits to control the cutoff frequency or the quality factor. Then design and simulation with auxiliary oscillator circuit AGC for controlling the oscillation frequency. Simulations are conducted with ideal models and with models that include some real properties. The conclusion of this work is devoted to the printed circuit board design for a selected filter circuit realization and measurement.
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Laboratory Tasks for Analogue Technology
Pavelka, Ondřej ; Haupt, Jaromír (referee) ; Langerová, Petra (advisor)
Předmět Analogová technika se zabývá základními analogovými funkčními bloky a jejich využití v současných elektronických zařízeních. Skládá se z přednášek a laboratorních cvičení, kde si studenti mohou ověřit nabyté znalosti v praxi. Tato práce obsahuje detailní návody s postupem řešení všech laboratorních úloh, měřených během celého semestru v laboratorních cvičeních. Tato cvičení slouží jako pomůcka pro lepší pochopení problematiky předmětu Analogová technika. Návody se skládají z teorie týkající se probíraného tématu, požadovanými úkoly, které má student splnit, schémat zapojení a pokud to daná úloha vyžaduje, tak i potřebných matematických vzorců k výpočtu požadovaných hodnot. Pro lepší názornost a k ověření správnosti postupů práce se v obvodech využije osciloskop. Návody také obsahují tabulky k vytištění a zapsání vypočítaných hodnot, které jsou výstupem některých úloh. Hlavním cílem této práce je zvýšit úroveň znalostí studentů předmětu Analogová technika a zvýšit efektivitu práce v laboratořích.
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Theremin
Musil, Petr ; Olejár, Adam (referee) ; Vlček, Lukáš (advisor)
This bachelor thesis focuses on the construction of the musical instrument theremin. Theoretical section of this thesis describes various types of oscillator and its potential use in construction of the musical instrument. Practical section of this thesis deals with specific circuit design, its simulation and construction of pitch control circuit, volume control circuit, mixer, preamplifier and supply voltage regulator. Principle of operation is based on mixing two high frequency signals produced by Colpitts oscillators.
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Universal active elements and their usage in frequency filters
Vencálek, Roman ; Kubánek, David (referee) ; Herencsár, Norbert (advisor)
This master’s thesis deals with the advanced universal modern active elements, such as the current and voltage conveyors. The problem with small bandwidth has been fixed due to the quick development in recent years. Current and voltage conveyors are still being researched. The good properties of conveyors promise their possible commercial usage in the future. For the research of current conveyors we can use parts of other integrated circuits and thus get elements with similar properties. This thesis suggests how to make an active filter using the DBTA and FDBTA elements which were created by “combination” of the universal current and voltage conveyor. Simulations were carried out on selected circuits containing the DBTA to verify their properties. It was for finding out about their behaviour in real applications that the circuits were constructed. This enabled the comparison of the results acquired from the simulation programs with the ideal behaviour of the elements and with the models simulating real properties against the values acquired by measurements of the circuits.
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Doppler blood flow indicator
Mojžíš, Karel ; Čížek, Martin (referee) ; Rozman, Jiří (advisor)
This bachelor´s thesis deals with basis of ultra-acoustics. The project presents basic information about Doppler effect. It describes the methods of processing and analyzing of velocity and direction of blood at doppler’s systems with modulated and unmodulated carrier wave. The project presents the system design of non-directional doppler indicator with unmodulated carrier wave for 8 MHz frequency, generating intensity of ultrasound 100 mW/cm2 and diameter D-shaped transmitting transducer 8 mm. This bachelor's thesis is concerned with circuit solution of a battery powered blood flow indicator with digital display. All the function blocks of the system are experimentally measured and their function is verified. The thesis contains complete materials for the construction of the doppler blood flow indicator.
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Evolutionary Optimisation of Analogue Circuits
Mihulka, Tomáš ; Zachariášová, Marcela (referee) ; Bidlo, Michal (advisor)
The aim of this work was to create a system for optimisaton of specific analog circuits by evolution using multiple fitness functions . A set of experiments was run, and the results analyzed to evaluate the feasibility of evolutionary optimisation of analog circuits . A requirement for this goal is the study and choice of certain types of analog circuits and evolutionary algorithms . For the scope of this work , amplifiers and oscillators were chosen as target circuits , and genetic algorithms and evolutionary strategies as evolutionary algorithms . The motivation for this work is the ongoing effort to automate the design and optimisation of analog circuits , where evolutionary optimisation is one of the options .
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Membraneless speaker
Kovář, Josef ; Šteffan, Pavel (referee) ; Pavlík, Michal (advisor)
The bachelor thesis consists of theoretic basics and describes the design and construction of one-channel membraneless speaker. Absence of mechanical components gives the membraneless speaker no frequency limitation. The design consists of power source, control electronics, which modulates the signal, convertor and output transformer. The power source is realized by transformer, which lowers the voltage and stabilizators. Modulation is provided by integrated circuit TL 594, its duty is adjusted by potentiometer P1 and frequency by potentiometer P2. Power conversion provides dual forward converter. As a output transformer was used transformer from color television.
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Study of Electronic Control and Real Behavior in Variable Filtering and Oscillating Applications of Modern Active Elements
Šotner, Roman ; Ondráček, Oldřich (referee) ; Martínek,, Pravoslav (referee) ; Petržela, Jiří (advisor)
The thesis deals with electronically adjustable and configurable applications of the modern active elements. In the field there were presented various active elements in applications of the analog filters and oscillators which stem from basic and more or less similar principles of circuit synthesis and design. However, there is not provided study of real behavior in detail and in most cases electronic control of the various parameters in application is not verified. In the precise design of application is very important to identify problematic features and determine how much it influences functionality of the device. In this work several filtering structures based on common and modified synthesis principles (integrator loops) are compared in the view of multifunctionality, configurability, variability, kind of used electronic control and impact of influences of real elements on behavior. There are used standard methods like adjusting of variable transconductance, intrinsic value of current input resistance and not so common method based on variable current gain in design of modified and improved multifunctional filtering circuits. The last method of mentioned control enabled to find quite unique filter which allows continuous electronic change of transfer from band-reject to all-pass filter of the 2nd order without reconnection. It is much simpler than previous and more common integrator loops. Larger part of this work is focused on electronically controllable oscillators mainly on quadrature types. There is presented several very simply and elementary realizations which require minimal number of active and passive elements. There are also slightly or more complicated solutions which remove some drawbacks of mentioned simpler variants. First of all there is given attention on study of real behavior which make obvious different problems with mutual dependence of oscillation condition and oscillation frequency, dependence of produced amplitudes (quadrature types) on parameter which is controlling oscillation frequency, influence of this parameter on oscillation condition, etc. In the framework of this part of the thesis there was introduced a novel modification of current conveyor transconductance amplifier (CCTA) so called current-gain-controlled current conveyor transconductance amplifier (CGCCCTA). Requirements for novel applications in the field of oscillators for newly developed controllable current amplifier and digitally controllable current amplifier (DACA) at the Department of Telecommunication FEEC BUT lead to creation of several chapters of this work where mentioned active elements can be used. The important contribution of this work (for practical approach) is also experimental testing of most of designed circuits and determination of exact design equations and rules which take into account real behavior of circuits and confirm results obtained from experiments.
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Design of magnetic bar-code read head
Kadlčík, Libor ; Drexler, Petr (referee) ; Mikulka, Jan (advisor)
Magnetic bar-code is composed from ferromagnetic bars printed on a substrate. The amount of ferromagnetic material is low, therefore reading magnetic barcode requires sensitive methods. Principle of methods of sensing both low-intensity magnetic field (fluxgates) and detecting low concentration of ferromagnetic material (resonant circuit, differential sensor) will be described. There are sensors producing frequency-modulated signal, therefore we focus on frequency demodulators as well. Signal acquired by sensor suffers from convolution distortion, reconstruction methods will be introduced. The assembled device consists of sensing oscillator, frequency demodulator, amplifier and reconstructing circuit. Frequency demodulation is done by phase-locked loop or differential demodulator. Reconstruction is based on detection of inflection points, producing square signal (representing bars of barcode). Design of these blocks is described. The device is able to read magnetic barcodes and reconstruct convolutionary distorted acquired signal. The differential demodulator exhibits low noise and low temperature drift (contrary to phase-locked loop). Signal produced by reading 2 mm wide bars is reconstructed without any problems, bars of width less than 1 mm cause troubles in certain cases (due to high degree of convolution distortion).
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