Fully analog aquarium for growing tropical plants

Cílem bakalářské práce bude objasnit problematiku týkající se pěstování tropických rostlin v akváriích. Hlavním aspektem práce bude rozbor ideálního prostředí pro domácí akvárium a volba specifických komponent pro růst rostlin. V dalších částech bude objasněn také návrh takovéhoto systému a jeho realizace v pokojových podmínkách.The aim of the thesis will be to clarify issues relating to the cultivation of tropical plants in aquariums. The main aspect of the work is to analyze the ideal environment for the home aquarium and the choice of specific components for plant growth. In the next sections will illustrate also the proposal of such a system and its implementation in ambient conditions.

Synthesis of circuit element with fractal dynamics

Prvním cílem této diplomové práce je objasnit tématiku týkající se obvodových prvků s fraktální dynamikou, naznačit jejich základní vlastnosti a možné aplikace v analogových elektronických obvodech se soustředěnými parametry. Druhým cílem je syntéza dvojpólů různých necelistvých řádů pro různé požadované změny fáze. Jejich optimalizace a aproximace v kmitočtové oblasti a následná realizace formou pasivních příčkových článků. Práce poté vyústí v realizaci univerzálního fraktálního PID regulátoru, ověření správné funkce tohoto mnohobranu v různých konfiguracích, a to jak simulací tak především měřením kmitočtových a časových odezev.The first aim of this diploma thesis is to clarify problems with circuit elements described by the fractional-order dynamics, show their basic properties and possible applications in circuits with lumped parameters. The second topic is covering the synthesis of two-terminal devices which have different fractional-orders for requested phase shifts. For this kind of devices, the thesis also describes their optimization and approximation in the frequency domain and subsequent implementation in the form of passive ladder structures. The final part of diploma work will be focused on practical realization of universal fractional PID controller and the verification of proper function of this multi-port in various configurations to prove its correct function via real measurement of frequency and time responses.

Electronically Tunable Oscillator Utilizing Reinforced Controllable Parameters

This paper presents a novel solution of an oscillator with electronically adjustable oscillation condition (CO) and frequency of oscillations (FO). Oscillation condition is controlled by current gain and frequency of oscillations is adjustable by transconductance and intrinsic resistance of used active elements. Both CO and FO are mutually independent. Moreover, special feature of CO allows boosting parameter driving FO (transconductance) and then shifting the whole FO range to higher bands. It allows to keep values of passive elements (capacitors especially) in satisfactory range even for higher value of FO. Simulations in PSpice confirms this hypothesis

Electronically Reconfigurable and Tunable Fractional-Order Filter Using Resonator Concept and Feedforward Path for Low-Frequency Tone Signalization

A novel electronically reconfigurable fractional-order filter allowing independent electronic frequency tuning and switchless change of the transfer response by a single parameter between standard band-pass, inverting all-pass response and special type band-reject response is presented in this work. The differences between these special transfer characteristics and standard features consist in magnitude and phase response behavior. Inverting amplification or attenuation is also available. The filter has tested frequency range between 1 Hz and 100 kHz. The proposed fractional-order filter (using two fractional-order element having equivalent capacity 8.7 uF/sec^1/4, =3 /4) tunability yields one-decade range approximately between 10 Hz and 100 Hz by transconductance between 0.19 and 1.1 mS (fractional-order design helps with reduction of driving force less than one decade). The application example in frequency/phase detector (operationability around center frequency 100 Hz - between 50 and 180 Hz) and further signaling frequency detecting system for frequency shift keying demodulator offers maximal detectable voltage (about 300 mV) for alignment (zero phase shift) of the signals of the same frequency (center frequency of the proposed filter in inverting all-pass mode). It also offers an interesting application in frequency shift keying demodulation process (or for identification/signalization purposes of certain frequencies) by usage of a simple additional comparator generating clear output state. Cadence simulations as well as experimental tests using integrated cells of special multipliers fabricated in ON Semiconductor 0.35 m I3T25 CMOS process confirm operationability of the proposed concept as well as simple application of special response of the filter for phase/frequency detection and demodulation purposes

Practical Design of Fractional-Order Oscillator Employing Simple Resonator and Negative Resistor

This contribution presents straightforward design of a fractional-order oscillator employing novel simple impedance inverter (implementing differential voltage current conveyor transconductance amplifier as active element) used for construction of parallel LC resonator and requiring also negative resistor. Design supposing two output waveforms with constant amplitude ratio and phase shift 155 degrees (–25 degrees) supposes two identical constant phase elements (fractional-order capacitors). The key advantages of our solution, stability of ratio of output levels and phase shift between generated waveforms, were confirmed by simulations

Electronically Reconfigurable Universal Filter Based on VDTAs

The proposed filter extends features of the previously presented Voltage Differencing Transconductance Amplifiers (VDTAs)-based frequency filter. It brings the new advantage of an electronic reconfiguration of its transfer. The proposed structure provides reconnection-less change between low-pass, band-pass, high-pass, band-stop and all-pass transfer functions. The electronic control of the filter parameters such as the pole frequency and quality factor remain preserved. The theoretical assumptions are supported by PSpice simulations using transistor-level models

Comparison of Simple Design Methods for Voltage Controllable Resistance

This paper compares several ways of electronic resistance control for tunable applications (filters, oscillators, amplifiers, etc.). Simulation (PSpice) and experimental tests of basic J-FET transistor-based adjustable resistor, optocoupler as well as more advanced active solutions using active devices (variable gain amplifiers, voltage-mode multiplier) are performed in order to see available linear range, readjustability range and expected frequency features