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6 th Oct, 2009. Linear Circuit analysis ( ELE101 ). Course Instructor : Engr. Khalil Ullah Lecturer Dept. of Electrical Engineering City University. Contents of Today’s Lecture. Course Syllabus Tentative Schedule An Important Note to the Students Introduction Before we begin
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6th Oct, 2009 Linear Circuit analysis (ELE101) Course Instructor: Engr. KhalilUllah Lecturer Dept. of Electrical Engineering City University
Contents of Today’s Lecture • Course Syllabus • Tentative Schedule • An Important Note to the Students • Introduction • Before we begin • Hints on problem solving • Basic Definitions
An Important Note to the Students • This is your first course in electrical engineering. Although electrical engineering is an exciting and challenging discipline, the course may intimidate you. A good textbook and a good professor are an advantage but you are the one who does the learning. If you keep the following ideas in mind, you will do very well in this course. • This course is a foundation for other courses • Solving problems is an essential part of learning • At the end of each chapter we will have a real-life example related to chapter being taught. • Attempt the exercise and some review questions at the end of each chapter • U should have strong mathematical background specially in matrices
Introduction • Technology is rapidly changing the way we do things; we now have computers in our homes,electronic control systems in our cars,cellular phones that can be used just about anywhere,robots that assemble products on production lines,and so on. • A first step to understanding these technologies is electric circuit analysis. • Circuit Analysis provides you with the knowledge of basic principles that you need to understand the behavior of electric and electronic devices,circuits,and systems. • In this course,we will develop and explore its basic ideas.
Before We Begin • Let us look at a few examples of the technology at work. • As we go through these, we will see devices and components that are not yet been discussed. Just concentrate on general Ideas. • As a first example, consider a VCR(Charles Ginsburg and Ray Dolby 1956 ) • Its design is based on electrical, electronic and magnetic circuit principles. • For example, resistors, capacitors, control the voltages and currents that operate its motors and transistors amplify the audio and video signals that are the heart of the system.
Example 1 • Figure 1. VCR Internal Circuitry
Hints on Problem Solving • Make a sketch (e.g.,a circuit diagram),mark on it what you know,then identify what it is that you are trying to determine. • Watch for “implied data”such as the phrase “the capacitor is initially uncharged”. (As you will find outlater,this means that the initial voltage on the capacitor is zero.) • Think through the problem to identify the principles involved,then look for • relationships that tie together the unknown and known quantities. • Substitutetheknowninformationintotheselectedequation(s)andsolvefortheunknown. • Check the answer to see that it is sensible—that is,is it in the “right ballpark”? Does it have the correct sign? Do the units match?
Linear Circuit Analysis • Circuit: • A closed path followed or capable of being followed by electric current • A configuration of electrically or electromagnetically connected components are devices. • An electric circuit is a connection of components (Voltage/Current sources; Resistors; Inductors & Capacitors ) such that there is some power supplied and dissipated. This means that if you connect a resistor to a battery using conductor wires, then you have created an electrical circuit. • Circuits are represented on a paper using diagrams
Circuit Diagrams • Block diagrams: • The • The over all circuits is broken into blocks. • Each block represent a portion of the system. • Flow is from left to right
Pictorial Diagram: • This helps in visualizing circuits and their operation by showing components as they actually appear.
Schematic Diagram: • Use simplified standard symbols to represent circuit components
Linear Circuit • That circuit which, for a sinusoidal input voltage of frequency f, any output of the circuit is also sinusoidal with frequency f. • Which obey the superposition principle. i.e. • linear circuit is one in which the values of the components, the resistance, capacitance, inductance, etc. don't change with the level of voltage or current in the circuit. • Examples: • Amplifiers, Differentiators, Integrators
Circuit Analysis Contd…. • The process of finding the voltage across and current flowing through each component in the circuit. • Different techniques are used to analyze a circuit • laws and the principles, concepts, mathematical relationships, and methods of analysis that have evolved from them are known as circuit theory • Circuit analysis is a special case of emf theory which concentrates on static and moving electric charges
Circuit Analysis • There are three basic assumptions in circuit analysis