INC 111 Basic Circuit Analysis Lecturer Associate Prof. Dr. Poj Tangamchit

About the Instructor Office: CB40603 (CB4 6th floor) Control System and Instrumentation Eng. (INC) Tel: x-9094 E-mail: poj.tan@kmutt.ac.th Research Interest: Robotics, Artificial Intelligence (AI) Lecture: Self-lecture. Reading material before coming to class is encouraged.

Course Details 3 Credits Class time 3 hours / week Review + Homework 6 hours/week E-learning material (DVD) is provided

Scoring & Grading Midterm Exam 40% Final Exam 40% Assignments Homework & Quiz (Pop quiz) 20% Grading follows the faculty of Engineering’s standard procedure.

Homework & Quiz & Assignment Homework takes time. Allocate 6-12 hours each week for it. Students need self-study outside class time.

Assignments Assignments Hand-on circuit design is involved.

Course Webpage http://www.inc.eng.kmutt.ac.th/inc111 Lecture Slides Homework Homework/ Quiz Solutions Announcements

Textbook Engineering Circuit Analysis, 8th edition McGrawHill William H. Hayt Jr., Jack E. Kemmerly, Steven M. Durbin

5V 800mA

Many things operate using Electricity. Why? How to make the electricity?

Faraday’s Law

Practical Electricity Generator Turbine

Coil Placement

3-phase system L1 N S L2 L3 N

Electric Outlet N L1 GND Alternating Current AC

5V 800mA Can this be used? Why?

Need an AC – DC converter. How does it look like?

No. 1 Input 120V AC 60Hz 0.1A Output 24V DC 100mA No

No. 2 Input 220V AC 50Hz Output 5V DC 500mA No

No. 3 Input 120~220V AC 50-60Hz Output 5V DC 2A Yes

Electricity Electricity is a result from the flow of electrons. Note: Electricity flows in the opposite direction of electron flow. = electron

Electric Current vs. Electron Current - + + - = Atom Structure - + + - - + + - - + + + + - - - + + electricity

Water We cannot see electric current. We need a metaphor. Which thing has similar property with electricity?? Water

Metaphor Electricity is similar to water flow. Water flows from high level to low level. Electricity flows from high voltage to low voltage. High Voltage Low Voltage

Measurement of Electricity Since we use electricity to do work for us, how Can we measure its energy? How can we measure the water power? Think about a water gun. High Voltage Low Voltage strong (fast, high kinetic energy) amount of water Voltage Current

Imagine the water power at the outlet

Electric Potential (ศักย์ไฟฟ้า) Which water drop has more impact force at the ground? Potential Energy (Height) transform Kinetic Energy (Velocity) Electric potential can be compared with the height of the water drop from the reference ground

Ground: Reference Point Normally, we measure height compared to the sea level. Also, electric potential at a point can be measured compared to the electric potential at the ground. Unit: Volt (V) Electric potential, or voltage has a unit “volt”. Ground always has 0 volts.

Voltage (ความต่างศักย์) Voltage is a difference of electric potential between 2 points Unit: Volt Compare to the height of 2 water drops

Electric Current (กระแส) Low current High current

Electric Current Unit Unit: Ampere, Amp (A) Note: Both current and voltage have directions

What is Circuit Analysis about? To calculate voltage or current at some points and some time in electric circuits

Course Overview DC (Direct current) AC (Alternating current) Circuits Voltage Current Voltage Current Constant voltage Constant current Midterm Time Phasor Concept Rules: Ohm’s law Kirchoff’s law Techniques: Mesh Analysis Node Analysis Superposition Thevenin/ Norton Frequency Transient Response

Topics Week 1: Introduction to Electricity, Simple DC circuits, Ohm’s law Week 2: Kirchoff’s voltage law, Kirchoff’s current law Week 3: Nodal Analysis Week 4: Mesh Analysis Week 5: Thevenin’s theorem Week 6: Norton’s theorem, Maximum power transfer theorem Week 7: Introduction to AC circuits and components Week 8: Midterm Exam Week 9: Transient response of RL circuits Week 10: Transient response of RC circuits Week 11: Transient response of RLC circuits Week 12: Phasor concept Week 13: Phasor circuit analysis Week 14: AC Power, Frequency response Week 15: Final Exam

Components Electric sources Independent Sources – voltage, current Resistors Measurement Devices Ammeters: measure current Voltmeters: measure voltage Ground – reference point Electric Wire

Symbol Independent Independent Voltage Current Source Source Resistor Ground Electric wire

General Rules All points on a same electric wire have the same voltage. A voltage source always have voltage difference of its pins equal to its value. A current source always have current pass through it equal to its value. Ground always has zero voltage. (0 volts)

Electric Flow Rule Electric current flows from high voltage to low voltage when there is a path. Electric current can freely pass through electric wire. Electric current can flow through a resistor with the amount according to Ohm’s law. Electric current can flow through a voltage source with the amount depended on other components in the circuit. Electric current can flow pass a current source according to its value.

Three Measurements of Electricity Voltage Volt (V) Current Ampere (A) Resistance Ohm (Ω)

Prefix Giga (G) 109 Mega (M) 106 Kilo (K) 103 Centi (c) 10-2 Milli (m) 10-3 Micro (μ) 10-6 Nano (n) 10-9 Pico (p) 10-12

Simple DC Circuit Current

Metaphor Increasing V is compared to ? Increasing R is compared to ? Current Increasing V is compared to ? Increasing R is compared to ?

Ohm’s Law V = IR Voltage (Volts) = for using with a resistor only V = IR Voltage (Volts) = current (Amperes) x resistance (Ohms) 2A 2Ω x+4 volts x volts Note: Electric wire has a resistance of 0 ohms

Electric Current 1A 1A 1A Every point in the circuit has current = 1A

Electric Voltage x + 1 Volts x Volts

Ground Ground = reference point always have voltage = 0 volts 1 Volts

Electric Voltage (2) 1 Volts 0 Volts 0 Volts

Electric Voltage (3) 1 Volts 1 Volts 0 Volts 1 Volts

Negative Voltage and Current + 2 volts - - -2 volts + Same as 1 A -1 A Same as

Power Symbol P has a unit of Watt P = VI I + V - Absorb power I - V + Generate power

Passive Sign Convention Absorb power: Power has a sign + Generate power: Power has a sign -

Example 2.5mA DC source generates power = 10V * -2.5mA = - 25mW Resistor absorbs power = 10V * 2.5mA = 25mW Note: Resistors always absorb power but DC source can either generate or absorb power

Direction of Voltage & Current on Resistors + - - + Resistor always absorb power. Therefore, it always have current flow through it from high voltage pin to low voltage pin.