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

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

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

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

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

6. Assignments
Assignments
Hand-on circuit design is involved.

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

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

9. 5V 800mA

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

11. Faraday’s Law

12. Practical Electricity Generator
Turbine

13. Coil Placement

14. 3-phase system L1 N S L2 L3 N

15. Electric Outlet N L1
GND
Alternating Current AC

16. 5V 800mA
Can this be used?
Why?

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

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

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

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

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

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

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

25. 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

26. 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

27. Imagine the water power at the outlet

28. 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

29. 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.

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

31. Electric Current (กระแส)
Low current
High current

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

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

34. 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

35. 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

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

37. Symbol Independent Independent Voltage Current Source Source Resistor
Ground
Electric wire

38. 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)

39. 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.

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

41. 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

42. Simple DC Circuit
Current

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

44. 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

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

46. Electric Voltage
x + 1 Volts
x Volts

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

48. Electric Voltage (2)
1 Volts
0 Volts
0 Volts

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

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

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

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

53. 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

54. 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.