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The design of rf impedance meter
Wiesner, Jiří ; Hrabina, Jan (referee) ; Roubal, Zdeněk (advisor)
The first part deals with the basic methods for measuring an unknown impedance. After determining the parameters of the desired impedance analyzer method was chosen AC unbalanced Wheatstone bridge. As a source of harmonic signal has been selected direct digital synthesis circuit and measure provides the analog vector voltmeter. Subsequently, it is discussed the issue of determining the sign of the unknown phase impedance. The thesis describes the wiring of circuit AD8302 and circuit AD9958 direct digital synthesis for which it is also an example of the code. It discusses the design and simulation of a reconstruction filter. Finally there are the measured output voltage and spectrum synthesizer.
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Wireless signal transfer from temperature sensors
Hulanský, Jozef ; Drexler, Petr (referee) ; Roubal, Zdeněk (advisor)
The main goal of this bachelor’s thesis is to design a device capable of measuring temperature to prevent danger in critical hot areas of high voltage electric distribution boxes. Hardware platform is focused on the Atmega8 chip from ATMEL Corp. factory. In this dokuments is elaborate the Zigbee wireless communication protocol, some types of temperature senzors and power system. The second part of this dokument are about the particular solution of measuring temperature and carrying values with wireless modules. This thesis also contains schematic and printed circuit board with pictures of system in work. In the end of this document are indicated experiences in the development of work and other possible solutions in the future.
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The design low noise linear power supply
Ondráš, Michal ; Steinbauer, Miloslav (referee) ; Roubal, Zdeněk (advisor)
This semester work describes the production of a power supply. It is linear source with voltage regulation and current regulation. The source has low output noise. The source is power supply for nuclear quadrupole resonance. This project describes NQR, linear source, noise, noise properties of electronic components and process for production of the power supply. The project describes select components with low noise and then influence on the electrics circuit and output noise. The text describes design the cooling system and calculation of the values.
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Air ion measurement
Lazorka, Martin ; Roubal, Zdeněk (referee) ; Špinka, Jiří (advisor)
This thesis focuses on the basic problems of ions and the ionization itself, what influence ions have to the organism. Further it examines compensation of small negative ions in the residential environment. Introduction to measurement of ion concentrations. First measurements with the aspiration capacitor which is now the most commonly used measurement of ion fields. Measurement is focused on the concentration of air ions in the building, VUT FEKT T-10, then the concentration changes depending on the daily cycle, ventilation and concentration before teaching and after teaching.
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Design of a new ion counter for the nature environment
Roubal, Šimon ; Szabó, Zoltán (referee) ; Roubal, Zdeněk (advisor)
Subject of this bachelors thesis is an realization of new control board for iontmeter that is developed at UTEE. Iontmeter must be capable of fully autonomous measure in outside contitions. That means it has to be able to run on batery for a long time and has to be to resist outside weather conditions. Measured data will be saved on an SD card and also sent using GSM network to the IoT server.
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Low level measurement
Roubal, Zdeněk ; Lazar, Josef (referee) ; Sládek, Petr (referee) ; Steinbauer, Miloslav (advisor)
The doctoral thesis presents methods for low-level measurements, which are exemplified by the general measurement of air ion concentration. Within the first section, the author progressively identifies certain critical effects influencing the concentration of air ions, and these effects are to be considered in evaluating the uncertainty of the measured concentrations. Thus, the thesis aims to provide a systematic description of the procedures and requirements related to low-level measurements; the proposed description then involves a discussion of the process reliability requirements, namely the factors of repeatability, elimination of errors, and definition and describability of measurement uncertainties. Such methodology facilitates, among other activities, the long-term monitoring of air ion concentration in extreme environments, including caves or spaces characterized by high temperatures and humidity. The use of common methods for determining the air ion mobility spectrum is accompanied by a number of disturbing effects, such as spurious fluctuation in the concentration of air ions in time. The experimental section of the thesis describes the testing of different configurations of the measuring device (a collecting electrode and a polarization capacitor); at this stage, we seek the most advantageous distribution of the electrostatic field in the sensor – a Gerdien tube. The systematic suppression of the influence of spurious fluctuations in air ion concentration during the measurement of saturation characteristics is carried out with the least-squares numerical method (as a supporting element), a hybrid technique to describe and evaluate the experimental model. In the second part of the thesis, the methodology of low-level measurement is complemented with procedures for the measurement of freezing potential. This latter domain, as an overall experimental approach applicable during phase changes of the sample, has hitherto not been sufficiently characterized from the metrological perspective, in an up-to-date manner; several subregions of the said domain remain somewhat obscured and deserve significantly more attention. In the given context, this thesis systematically considers a problem where comparable measurement results produced by multiple authors are not available. The measuring methodology proposed herein was utilized in applied research to facilitate the fabrication of an apparatus for the experimental measurement of freezing potential in pre-defined samples; the obtained results then lead us to conclusions with respect to the evaluation of effects that cause differences in the measured data, and the results can be further compared with those obtained by other researchers investigating the given segment of the problem.
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SMD Rework station
Szabó, Michal ; Roubal, Zdeněk (referee) ; Szabó, Zoltán (advisor)
This thesis describes the theory of solder joint and conditions under which it is formed correctly. Further, methods of hand soldering are discussed, and possibilities of temperature regulation of soldering tip are analyzed. Methods of creating a soldering station and its key features are depicted. In practical part, the solution of how to create a soldering station with soldering iron, desolder gun and heatgun is given and is constructed. While testing a defect is found that prevents the power portion of soldering station to function properly and prevents completion.
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Signal generator controlled by AVR
Wiesner, Jiří ; Steinbauer, Miloslav (referee) ; Roubal, Zdeněk (advisor)
The aim of this thesis was to design a universal function generator, which would find use for magnetizing and demagnetizing job, or for measuring hysteresis. The heart of the control module is an 8-bit microcontroller from Atmel, they are connected to the input/output peripherals, not least optocouplers for relay. Microcontroller communicates with the other module mounted DA converters using the SPI lines. At the exit so they can rise to any signals programmed into the MCU.
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High resolution ammeter
Honek, Marek ; Roubal, Zdeněk (referee) ; Steinbauer, Miloslav (advisor)
A transmission electron microscope is a device operating on a similar principle as an optical microscope. The fact that electrons wavelength is much shorter than the wavelength of photons is used to obtain huge magnifications. Glass lenses commonly used in the optical microscope are therefore replaced by magnetic coils in the electron microscopes. A magnetic field is directly proportional to the current passing through these coils. It is important to the current supplied to the coils to be as stable as possible to achieve high resolution. The goal of this thesis is to analyze usable current measurement methods and to design a current stable measuring device with a resolution of 1 ppm.
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Design and optimalization switched power source controlled by microcontroller
Smejkal, Vít ; Bartušek, Karel (referee) ; Roubal, Zdeněk (advisor)
This thesis deals with an introduction to the theory of switching power supplies and with properties of magnetic materials. Special attention is paid to nanocrystalline materials. It also discusses the issues of simulating the behavior of ferromagnets. The properties of commonly used ferrite material and nanocrystalline materials was measured. Using the created program for the design of forward converter is designed a switching power supply to verify its proposal. Design optimization is based on using a nanocrystalline core, which allows to reduce the operating frequency.
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