LECT giới thiệu về ngành cơ điện tử

gới thiệu chung về ngành cơ điện tử các kiến thức cần biết về ngành. tiếng anh chuyên ngành cơ điện tử. ứng dụng của ngành trong cuộc sống hàng ngày và các linh kiện bán dẫn thường dùng trong đời sống hàng ngày

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Lecture 1

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SMART Funded by The National Science Foundation

What is Current?

• A flow of electrically charged particles

• Carried by small negatively-charged

particles, called electrons

• Represented by the symbol I, and is

measured in amperes, or 'amps', A

• Most often measured in milliamps, mA

• Like water flow

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Water Analogy

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Series Connection of Cells

• Each cell provides 1.5 V

• Two cells connected one after another, in series, provide

3 V, while three cells would provide 4.5 V

• Polarities matter

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Parallel Connection of Cells

• If the cells are connected in parallel, the voltage stays

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DC and AC

• A cell provides a steady voltage, so that current flow is always in the same direction

– This is called direct current, or d.c

• The domestic mains provides a constantly changing voltage which reverses in polarity

60 times every second

– This gives rise to alternating current, or a.c

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Power Supply

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Water Analogy of Wires

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• Dissipative elements that convert electrical

energy into heat

• Resistors limit current

• Unit is ohms, Ω Resistor Symbols

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Water Analogy of Resistor

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Resistors of Different Sizes

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How to Read Resistor Values 1

1 By color code

2 By digital multi meter (DMM)

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How to Read Resistor Values 2

By color code

Resistor value = AB × 10 C ± tol %( Ω )

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Resistance Color Code

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Example

• The first band is yellow, so the first digit is 4

• The second band is violet, so the second digit is 7

• The third band is red, so the multiplier is

• Resistor value is 47 ×××× 10 2 ±±±± 5 %( Ω )

2

10

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Metric Units and Conversions

Abbreviation Means Multiply unit by Or

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Examples

0.01

http://www.electrician.com/resist_calc/resist_calc.htm

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Digital Multimeter 1

• DMM is a measuring instrument

• An ammeter measures current

• A voltmeter measures the potential

difference (voltage) between two points

• An ohmmeter measures resistance

functions, and possibly some

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– Without any power supplied

• Adjust range (start from highest limit if you don’t know)

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Digital Multimeter 3

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Ammeter Connection

• Break the circuit so that the ammeter can be connected in series

• All the current flowing in the circuit must pass through the ammeter

• An ammeter must have a very LOW input impedance

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Voltmeter Connection

• The voltmeter is connected in parallel between two points of circuit

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Resistors in Series

Rtotal=R1+R2

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Resistors in Parallel

Ω

=

= +

R R

R

R R

total

5

0 2

1 1

1

1 1

21

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Exercise 1

Ω

=

= +

× +

=

+

× +

=

k R

R R

R

R R

R

total

5

1 2

3 1

1

1 1

32

1

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Exercise 2

10Ω

Pot

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Potentiometer 2

Terminal B Wiper Terminal A Terminal B Wiper Terminal A

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Rotary Potentiometers

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Linear Potentiometer

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Breadboard 1

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Breadboard 2

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How to Insert a Component into a

Breadboard

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Resistor Experiments

StampWorks

On coming slides Others

Robotics Earth measurements

Basic A and D

What’s micro controller

Chapters Experiments

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Experiment Details 1

1 Read resistors’ nominal values using color code

2 Determine resistors’ values using an Ohmmeter

3 Determine resistors’ values using DMM (Voltmeter and

Ammeter) and compare with results from 1 and 2

4 Make serial connection with two resistors

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