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Chapter 01

Introduction

Source: Circuit Analysis: Theory and Practice Delmar Cengage Learning C-C Tsai 2

Hints on Problem Solving

First - Make a sketch

Mark on it what you want to know

Identify what you are trying to determine

Convert implied data to explicit data

Second – Think through the problem

Identify relationships that unknown and known quantities

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Hints on Problem Solving

Third - Substitute known information into selected equations

solve for unknown quantity

Fourth - Check the answer

Is it in the “right ballpark”?

Does it have the correct sign?

Do the units match?

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Examples of Technology at Work

Electric circuit theory

First step to understanding electronic technologies

Example: home theater system

Electrical and electronic circuits

Magnetic circuits operate speaker system

Laser circuitry used to read data

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Typical Electronic Components

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Electronic Components - Resistors

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Electronic Components - Capacitors

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Electronic Components

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Electronic Components

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SI System of Units

Based on MKS or CGS

Length

Meter (m); Centimeter (cm)

Mass

Kilogram (kg) ; Gram (g)

Time

Second (s)

Electric Current

Ampere (A)

Temperature

Celsius (C) ; Fahrenheit (F) ; Kelvin (K)

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Definition of Units

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Definition of Units (cont’d.)

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Definition of Units (cont’d.)

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Relative Size of the Units

1 meter is about 1 yard (=0.9144 m)

1 inch (=2.54 cm) is about 2½ centimeters

1 newton is about the force required to lift a ½ -pound weight

Raising a ½ -pound weight 1 meter in 1 s requires about 1 watt

Room temperature is about 25 degrees Celsius (25C) or about 290 degrees Kelvin

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Converting Units

Convert 60 miles/hour to km/hr

1 mile = 1.609 km

60 miles/hour = 96 kms/hour

A circle has radius of 6 inches

Determine the area in square meters

A = r 2 = 3.14 x (2.54cmx6)2

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Power of Ten Notation

Used to express very large and small numbers

Number 10 is called the base, the power is called the exponent

For example:

35 000 = 3.5 × 104 = 35 × 103

458 000 = 4.58 × 105 = 458 × 103

0.000 042 = 4.2 × 10-5 = 42 × 10-6

0.000 159 = 1.59 x 10-4 = 159 x 10-6

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Multiplication and Division using Powers of Ten

To multiply numbers in power of ten notation

Multiply their base numbers

Add their exponents (e.g., 103 x 105 = 108)

To divide numbers in power of ten notation

Divide their base numbers

Subtract their exponents in the denominator from exponent in the numerator

(e.g., 109/103 = 106)

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Adjust all numbers to same power of ten

Can choose any exponent: as long as they are all the same

For example:

3 x 104 + 5 x 103 = 35 x 103 (changing both powers of ten to 3)

Or

3 x 104 + 5 x 103 = 3.5 x 104 (changing both powers of ten to 4)

Addition and Subtraction using Powers of Ten

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Power of Ten Notation

Raising a number to a power

Form of multiplication if exponent is positive

Form of division if exponent is negative

For example:

(4 × 103)2 = (4 × 103)(4 × 103)

= 16 × 106

Integer fractional powers represent roots

For example:

92

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Prefixes – Engineering Notations

More common to use prefixes than powers of ten.

Scientific Notation

24 700 = 2.47 × 104

0.000 046 = 4.6 × 10-5

Engineering Notation

Uses only powers that are factors of 3

24 700 = 24.7 × 103

0.000 046 = 46 × 10-6

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Engineering Prefixes

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Numerical Results

Significant digits

Number of significant digits in a result that carry information.

It is a common error to show more digits of accuracy than are warranted

Measured values have an element of uncertainty

Applies to computations based on them also

Carry all digits throughout the problem

Round answer to a suitable number of digits

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Exercise 1

1. Please show their electronic symbols and units for voltage, current, resistor, and capacitor.

2. Please show their represented prefix (i.e., power of ten notation), 103~1012 and 10-3~10-12.

3. Answer the following questions.

(a) 0. 24 MΩ = ______kΩ

(b) 0.0024 μF = ______ pF

(c) 330 Ω + 2.7 k Ω = _________ Ω

(d) 0.5 mA – 200 μA = _________ A

(e) 10 mA / 40 μA = ___________

(f) 10V / 40 k Ω = _________A

(g) 25 μA * 6 kΩ = _________V

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Circuit Diagrams

Electric circuits

Use batteries and resistors as components

Circuit diagrams are used on paper

Three types are used

Block diagram,

Pictorial diagram, and

Schematic diagram.

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Block Diagrams

Blocks represent portions of a system

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Pictorial Diagrams

Provide detail

Show components as they actually look

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Schematic Diagrams

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Schematic Circuit Symbols

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Circuit Analysis using Calculators and Computers

Calculators and Computers widely used for circuit design and analysis

Electronic Calculators

TI-86, TI-89

Simulation software

PSpice, Multisim (Electronics Workbench)

Numerical analysis software

MathCAD, MATLAB

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Prepackaged Math Software

MathCAD or MATLAB

Uses numerical analysis techniques

Requires no programming

Data is entered; computer does the work

Uses standard mathematical notation

Useful for solving simultaneous equations

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Circuit Simulation Software

PSpice or Multisim

Most use a software engine called SPICE

(Simulation Program In Circuit Emphasis)

P Spice, H Spice, All Spice, Z Spice, Multisim

Solves problems by simulating circuit behavior

Select components to build circuit on screen

Test circuit without building a hardware prototype

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Multisim

Orcad- PSpice

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Exercise 2

1. What is the mean of SPICE?

2. Two switches installed on the up-stair and down-stair, respectively, can control a lamp on or off, please show the schematic diagram.

3. Why the bird is not to get electric shock?

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Kernel abilities

1. An animal is whether electric shock or not, Please explain why?

2. What are engineering prefixes? Please give some representative literatures for power of ten notations.

3. What are the symbol and unit of quantities?

Please give some examples.

4. What are the schematic symbols of electric components? Please give some examples.

5. What are tools of computer-aided circuit analysis? Please give some representative tools.

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Problem 56: Draw the Schematic diagram from the following Pictorial diagram.

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Exercise 3 using Multisim

1. Using Multisim to check the answer of the following

question, 10V / 40 k Ω = _________A

2. Using Multisim to check the answer of the following

question, 25 μA * 6 kΩ = _________V

3. Using Multisim to check the function that Two

switches installed on the up-stair and down-stair,

respectively, can control a lamp on or off.