Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 EE 1105 : Introduction to EE Freshman Seminar Lecture 2: Signals, Systems and Circuits Credit: Dr. Bill Dillon, Dept. of Electrical Engineering, UTA National Instruments MyDAQ and LABVIEW

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 EE Jargon Device: primitive element –Passive (no power source needed), electric: ex: Resistor vs: - Active (need power source), electronic: ex: Transistor Analysis: Understand how a given circuit works Design (Synthesis): Understand how to build the circuit from requirements Signals – inputs and outputs to devices, circuits, and systems –AC (time varying) –DC (constant)

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Classifications of Systems By Application Areas Communications Systems Computer Systems Control Systems Electromagnetics Electronics Power Systems Signal Processing Systems

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Communications Systems Telephony –Analog and Digital –Switched Channels Radio –Broadcast AM, FM, & SW –Two-Way Television

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Computer Systems Programmable Microcircuits High-speed switching of logic circuits Used for –Computation –Control

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Control Systems Automated Adaptable Faster Operation than Manual More Reliable than Manual Modern high-performance aircraft rely on automated control systems

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Electromagnetics Antennas for Sending & Receiving Information –Cell Phones –Satellite Dishes Magnetrons for generation of Microwave Energy Induction Heating for Industrial processes

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Electronics Material Properties Devices Circuits Used for Detecting, Amplifying and Switching Electrical Signals

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Power Systems Large networks connected by low frequency a-c transmission lines Small networks in aircraft and spacecraft Electromechanical Energy Conversion Power Electronics –High frequency switching converters –High efficiency, high power density

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Signal Processing Systems Transform and manipulate signals and the information they contain Image processing –Data from weather satellites –MRI scans of the human body Noise reduction Encryption

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 BSEE Degree Plan Dr. Saibun Tjuatja, UG Advisor

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Intellectual Themes of EE Modularity (ex: device) –Manage complexity by reusing simple components (electrical, mechanical or code) nomenclature: devices Abstraction (ex: circuit, system) –Represent complex systems by connecting modules using interconnects Block diagrams, Data flow diagrams (state machines), signal flow graphs, electric circuits Modeling (ex: electronic vs electric) –Represent behavior of systems using mathematical abstractions

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Signals and Systems –Signal: Conventional Electrical or Optical signals Any time dependent physical quantity AC or DC –System: Object in which input signals interact to produce output signals. Linear vs Nonlinear systems –Fundamental properties that make it predictable: »Sinusoid in, sinusoid out of same frequency (when transients settle) »Double the amplitude in, double the amplitude out (when initial state conditions are zero) Images Source: Internet

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 System Modeling Building mathematical models based on observed data, or other insight for the system. –Parametric models (analytical): ODE, PDE –Non-parametric models: ex: graphical models - plots, or look-up tables. –Mental models – Ex. Driving a car and using the cause-effect knowledge –Simulation models – ex: Many interconnect subroutines, objects in video game

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Types of Models White Box –derived from first principles laws: physical, chemical, biological, economical, etc. –Examples: RLC circuits, MSD mechanical models (electromechanical system models). Black Box –model is entirely derived from measured data –Example: regression (data fit) Gray Box – combination of the two

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Abstraction: Ideal Circuit A circuit model is usually two or more circuit elements that are connected. A circuit model may have active elements (sources) as well as passive elements (such as resistors). By the assumption that electric signal propagation is instantaneous in a circuit, our circuit model has lumped parameters.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Example of a Circuit

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Model: Kirchhoff’s Voltage Law The sum of the voltage drops around a closed path is zero. Example: V 1 + V 2 + V 3 + V 4 = 0

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 MyDAQ General Purpose Data Acquisition Device from National Instruments (NI) Multimeter, Oscillocope, Function Generator, Spectrometer and much more = + + $50-$200 $300-$10,000 $300-$5,000 $200 + much more

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 LabVIEW programs are called: –Virtual Instruments (VIs) –because their appearance and operation imitate actual instruments. However, they are analogous to main programs, functions and subroutines from popular language like C, Fortran, Pascal, …

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Abstraction: LabVIEW Programs Virtual Instruments (VIs) Front Panel Controls = Inputs Indicators = Outputs Block Diagram Accompanying “program” for front panel Components “wired” together

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Primitive Modules The basic primitive building blocks in LabVIEW include –Numbers – formatted according to type (e.g. integer, boolean, float, etc.) –Loops – While, For –Logical and Arithmetic Ops – Comparator, Summer, Adder –GUI Elements – Button, Knob, Dial

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 More Complex Modules More complex blocks in LabVIEW include –Arrays, Clusters, Enums –Signals and Transfer Functions –Data statistics, Graphs

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Abstraction: Dataflow Programming In this case, the block diagram executes from left to right, not because the objects are placed in that order, but because the Subtract function cannot execute until the Add function finishes executing and passes the data to the Subtract function. Remember that a node executes only when data are available at all of its input terminals and supplies data to the output terminals only when the node finishes execution.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Basic Concepts: Charge Charge is measured by amounts of electrons or protons in matter, measured in multiple of e=1.6 x 10^-19 C(oulombs) The charge density in materials depends on type of material (conductor, semiconductor, insulator) Images Source: Internet

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Voltage and Current Voltage is the energy per unit of charge. Current is the rate of flow of charge.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Voltage and Current (continued) The relationship between voltage and current in a circuit element defines that circuit element. Both voltage and current have associated polarities. These polarities determine the direction of power flow.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Ideal Basic Circuit Element Three attributes of an ideal circuit element: –There are only two terminals –Described mathematically in terms of current and/or voltage –Cannot be subdivided into smaller components

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Five Fundamental Elements Ideal Voltage Sources –Independent –Dependent Ideal Current Sources –Independent –Dependent Resistors Inductors Capacitors

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Voltage Polarity Definitions Positive v –voltage drop from 1 to 2 or –voltage rise from 2 to 1 Negative v –voltage drop from 2 to 1 or –voltage rise from 1 to 2

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Current Polarity Definitions Positive i –Positive charge flowing from 1 to 2 –Negative charge flowing from 2 to 1 Negative i –Positive charge flowing from 2 to 1 –negative charge flowing from 1 to 2

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Passive Sign Convention Whenever the reference direction for the current in an element is in the direction of the reference voltage drop, use a positive sign in any expression that relates voltage to current. Otherwise, use a negative sign.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Power and Energy Power associated with a circuit element is consumed by that circuit element when the value of power is positive. Conversely, power is generated, or produced by the element if the value consumed is negative.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Expression of Power

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Independent Voltage Source Voltage may be constant or time- dependent Delivers nominal terminal voltage under all conditions

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Independent Current Source Current may be constant or time- dependent Delivers nominal terminal current under all conditions

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Electrical Resistance (Ohm’s Law) Electrical resistance is the ratio of voltage drop across a resistor to current flow through the resistor. Polarities are governed by the passive sign convention.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Power Consumed by Resistors Resistors consume power. v and i are both positive or both negative.

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Conductance Defined Conductance is the reciprocal of resistance. The units of conductance are called siemens (S) The circuit symbol is G

Dan O. Popa, Intro to EE – Freshman Seminar, Spring 2015 Homework 2 due next class!! Available online at course website Credit: Dr. Bill Dillon, Dept. of Electrical Engineering. Questions? 40