Anh văn chuyên ngành cơ khí

DANANG UNIVERSITY
UNIVERSITY OF SCIENCE AND TECHNOLOGY
FALCUTY OF MECHANICAL ENGINEERING

Danang, 2017


TABLE OF CONTENTS
TABLE OF CONTENTS .......................................................................................... i
ELECTRONIC SYSTEMS ...................................................................................... 1
CHAPTER 1: INTRODUCTION ....................................................................................1
LOGIC GATES .................................................................................................................... 2

CHAPTER 2: LOGIC GATES ........................................................................................7
INTEGRATED CIRCUIT .................................................................................................... 7
APPLICATIONS .................................................................................................................. 8

CHAPTER 3: BASIC ELECTRONIC COMPONENTS ............................................10
RESISTANCE .................................................................................................................... 10
CAPACITOR ...................................................................................................................... 12
DIODE ................................................................................................................................ 13
LIGHT EMITTING DIODE ............................................................................................... 16
BIPOLAR JUNCTION TRANSISTOR (BJT) ................................................................... 20

CHAPTER 4: MICROCONTROLLER .......................................................................22
INTRODUCTION .............................................................................................................. 22
IMPORTANT FEATURES ................................................................................................ 24
WHY PIC? .......................................................................................................................... 31

MECHANICAL SYSTEMS................................................................................... 33

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CHAPTER 1: INTRODUCTION ..................................................................................33
MECHANISMS .................................................................................................................. 33
TYPES OF MOTION ......................................................................................................... 35
DEGREE OF FREEDOM................................................................................................... 35

CHAPTER 2: CAMS ......................................................................................................37
ECCENTRIC CAM ............................................................................................................ 38
DROP CAM ........................................................................................................................ 39
FLAT CAM ........................................................................................................................ 41

CHAPTER 3: GEARS ....................................................................................................43
SPUR GEAR....................................................................................................................... 44
HELICAL GEAR................................................................................................................ 45
DOUBLE HELICAL GEAR .............................................................................................. 46
BEVEL GEAR .................................................................................................................... 47
WORM GEAR .................................................................................................................... 48
RACK AND PINION ......................................................................................................... 50
GEAR TRAIN .................................................................................................................... 51

CHAPTER 4: BELT AND CHAIN DRIVES ...............................................................54
PROS AND CONS ............................................................................................................. 55
FLAT BELTS ..................................................................................................................... 55
ROUND BELTS ................................................................................................................. 57
VEE BELTS........................................................................................................................ 57
TIMING BELTS ................................................................................................................. 59

CHAIN DRIVE ................................................................................................................... 60

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CHAINS VERSUS BELTS ................................................................................................ 61

CHAPTER 5: BEARINGS .............................................................................................63
DEEP-GROOVE................................................................................................................. 64
FILLING - SLOT ................................................................................................................ 65
ANGULAR CONTACT ..................................................................................................... 65
DOUBLE-ROW .................................................................................................................. 67
SELF-ALIGNING .............................................................................................................. 68
STRAIGHT-ROLLER BEARING ..................................................................................... 69
TAPER ROLLER ............................................................................................................... 70
NEEDLE ROLLER ............................................................................................................ 72

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1
ELECTRONIC SYSTEMS
CHAPTER 1: INTRODUCTION
Many control systems are concerned with setting events in motion or stopping
them when certain conditions are met. For example, with domestic washing machine,
the heater is only switched on when there is water in the drum and it is to the

prescribed level. Such control involves digital signals where there are only two
possible signal levels. Digital circuitry is the basis of digital computers and
microprocessor controlled systems. There are two input signals which are either 1 or
0 signals and an output signal which is 1 or 0 signal. The controller is here
programmed to only give a 1 output if both the input signals are 1. Such an operation
is said to be controlled by a logic gate .Logic gate is the basic building blocks for
digital electronic circuits. The term combinational logic is used for the combining of
two or more basic logic gates to form a required function.
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LOGIC GATES
Logic gates are the basic components in digital electronics. They are used to
create digital circuits and even complex integrated circuits. For example, complex
integrated circuits may bring already a complete circuit ready to be used –
microprocessors and microcontrollers are the best example – but inside them they
were projected using several logic gates. In this tutorial we will teach you everything
you need to know about logic gates, with several examples.
As you may already know, digital electronics accept only two numbers, “0” and
“1.” Zero means a 0 V voltage, while “1” means 5 V or 3.3 V on newer integrated
circuits. You can think “0” and “1” as a light bulb turned off or on or as a switch
turned off or on.

AND gate: Suppose we have a gate giving a high output only when both input A
and input B are high; for all other conditions it gives a low output. This is an AND
logic gate. We can visualize the AND gate as an electric circuit involving two switches
in series. Only when switch A and B are closed, there is a current.

(a) Represented by switches

(b) Symbols

The relationship between the inputs and the outputs of an AND gate can be
expressed in the form of an equation, called Boolean equation. The Boolean equation
for the AND gate is written as
A.B=Y
An example is a burglar alarm in which it gives an output, the alarm sounding,
when the alarm is switched on and when a door is opened to active a sensor.

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The relationships between inputs to a logic gate and the outputs can be tabulated
in a form known as truth table. This specifies the relationships between the inputs
and outputs. We can write the truth table as

A

B

0

0

0

1

1

0

1

1

Output

OR gate: An OR gate with inputs A and B gives an output of a 1 when A or B is 1.
We can visualize such a gate as an electric circuit involving two switches in parallel.
When switch A or B is closed, then there is a current. OR gates can also have more
than inputs. We can write the Boolean equation for an OR gate as:
A+B=Y

(a) Represented by switches

A

B

0

0

0

1

1

0

1

1

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(b) Symbols

Output

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NOT gate: a NOT gate has just one input and one output, giving a 1 output when
the input is 0 and a 0 when input is 1. The NOT gate gives an output which is the
inversion of the input and is called an inverter. The 1 representing NOT actually
symbolizes logic identity, i.e. no operation, and the inversion is depicted by the circle
on the output. Thus, if we have a digital input which varies with time, the output
variation with time is the inverse.
The Boolean equation describing the NOT gate is

AY
A bar over a symbol is used to indicate that the inverse, or complement, is being
taken; thus the bar over the A indicates that the output Y is the inverse value of A.

Input

Output

1
0

NAND gate: The NAND gate can be considered as a combination of an AND gate
followed by a NOT gate. Thus when input A is 1 and input B is 1, there is an output of
0, all other inputs giving an output of 1.
The NAND gate is just the AND gate truth table with the outputs inverted. An
alternative way of considering the gate is as an AND gate with a NOT gate applied to
invert both the inputs before they reach the AND gate. The figure below shows the
symbols used for the NAND gate, being the AND symbol followed by the circle to
indicate inversion.

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The Boolean equation describing the NAND gate is:

A B  Y
The following is the truth table:

A

B

0

0

0

1

1

0

1

1

Output

NOR gate: The NOR gate can be considered as a combination of an OR gate
followed by a NOT gate. Thus when input A or input B is 1 there is an output of 0. It is
just the OR gate with the outputs inverted. An alternative way of considering the gate
is as an OR gate with a NOT gate applied to invert both the inputs before they reach
the OR gate. The figure below shows the symbols used for the NOR gate; it is the OR
symbol followed by the circle to indicate inversion.

The Boolean equation for NOR gate is:

A B Y
The following is the truth table for the NOR gate.

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A

B

0

0

0

1

1

0

1

1

Output

XOR gate: XOR stands for exclusive OR. XOR gate compares two values and if they
are different its output will be “1.” XOR operation is represented by the symbol ⊕. So

Y = A ⊕ B is the Boolean equation for the XOR gate.

The following is the truth table for the XOR gate.

A

B

0

0

0

1

1

0

1

1

Output

XNOR gate: XNOR stands for exclusive NOR and is an XOR gate with its output
inverted. So, its output is at “1” when the inputs have the same value and “0” when
they are different. XNOR operation is represented by the symbol (·). The Boolean
equation for XNOR gate is:

A (·) B = Y

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CHAPTER 2: LOGIC GATES
INTEGRATED CIRCUIT
Logic gates are available as integrated circuits. The different manufacturers have
standardized their numbering schemes so that the basic part numbers are the same
regardless of the manufacturer. For example, Fig. 1(a) shows the gate systems
available in integrated circuit 7408; it has four two-input AND gates and is supplied
in a 14-pin package. Power supply connections are made to pins 7 and 14, these
supplying the operating voltage for all four AND gates. In order to indicate at which
end of the package pin 1 starts, a notch is cut between pins 1 and 14. Integrated
circuit 7411 has three AND gates which each having three inputs; integrated circuit
7421 has two AND gates with each having four inputs. Figure 1(b) shows the gate
systems available in integrated circuit 7402. This has four two-input NOR gates in a
14-pin package, power connections being to pins 7 and 14. Integrated circuit 7427
has three gates with each having three inputs.

Figure 1: Integrated circuit (a) 7408, (b) 7402

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APPLICATIONS

1. Digital comparator
A digital comparator is used to compare two digital words to determine if they
are exactly equal. The two words are compared bit by bit and a 1 output given if the
words are equal. To compare the equality of two bits, an XOR gate can be used; if the
bits are both 0 or both 1 the output is 0, and if they are not equal the output is a 1. To
obtain a 1 output when the bits are the same we need to add a NOT gate, this
combination of XOR and NOT being termed an XNOR gate. To compare each of the
pairs of bits in two words we need an XNOR gate for each pair. If the pairs are made
up of the same bits then the output from each XNOR gate is a 1. We can then use an
AND gate to give a 1 output when all the XNOR outputs are ones. Figure 2 shows the
system.

A0
B0

A1
B1
A=B
A2
B2

A3
B3

2. Coder
The Fig. 3 shows a simple system by which a controller can send a coded digital
signal to a set of traffic lights so that the code determines which light, RED, AMBER
OR GREEN, will be turned on. To illuminate the RED light we might use the
transmitted signal A = B = 0, for the AMBER light A = 0, B = 1 and for the GREEN light
A = 1, B = 0. We can switch on the lights using these codes by using three AND gates

and two NOT gates.

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A

RED

B
AMBER

GREEN

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CHAPTER 3: BASIC ELECTRONIC
COMPONENTS
RESISTANCE
The electrical resistance of an object is a measure of its opposition to the passage
of a steady electric current. An object of uniform cross section will have a resistance
proportional to its length and inversely proportional to its cross-sectional area, and
proportional to the resistivity of the material.
Discovered by Georg Ohm in the late 1820s, electrical resistance shares some
conceptual parallels with the mechanical notion of friction. The SI unit of electrical

resistance is the ohm, symbol Ω. Resistance's reciprocal quantity is electrical
conductance measured in Siemens, symbol S.
The resistance of a resistive object determines the amount of current through the
object for a given potential difference across the object, in accordance with Ohm’s
laws:
I

where

V
R

R is the resistance of the object, measured in ohms, equivalent to J·s/C2
V is the potential difference across the object, measured in volts
I is the current through the object, measured in amperes

We all know that voltmeter and ammeter are used for measuring the voltage and
the current respectively. For the resistance, the meters that use to measure it is the
ohmmeter. But what if we don't have an ohmmeter to use?
Color coding system for resistors consists of three colors to indicate the
resistance value in ohms of a certain resistor, sometimes the fourth color indicate the
tolerance value of the resistor. By reading the color coded in correct order and
substituting the correct value of each corresponding color coded as shown in the
table below, you can immediately tell all you need to know about the resistor. Each
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color band represents a number and the order of the color band will represent a

number value. The first 2 color bands indicate a number. The 3rd color band indicates
the multiplier or in other words the number of zeros. The fourth band indicates the
tolerance of the resistor. In most cases, there are 4 color bands. However, certain
precision resistors have 5 bands or have the values written on them, refining the
tolerance value even more.

1st
Band

2nd
Band

3rd
Band

Black

0

0

0

100 Ω

Brown

1

1

1

101 Ω

Red

2

2

2

102 Ω

Orange

3

3

3

103 Ω

Yellow

4

4

4

104 Ω

Green

5

5

5

105 Ω

Blue

6

6

6

106 Ω

Violet

7

7

7

107 Ω

Gray

8

8

8

108 Ω

White

9

9

9

109 Ω

Color

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4th band

5th Band
(multiplier) (Tolerance)

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CAPACITOR
A capacitor (formerly known as condenser) is a passive two-terminal electrical
component used to store energy in an electric field. The forms of practical capacitors
vary widely, but all contain at least two electrical conductors separated by a
dielectric (insulator); for example, one common construction consists of metal foils
separated by a thin layer of insulating film. Capacitors are widely used as parts of
electrical circuits in many common electrical devices.
When there is a potential difference (voltage) across the conductors, a static
electric field develops across the dielectric, causing positive charge to collect on one
plate and negative charge on the other plate. Energy is stored in the electrostatic
field. An ideal capacitor is characterized by a single constant value, capacitance,
measured in farads. This is the ratio of the electric charge on each conductor to the
potential difference between them.
The capacitance is greatest when there is a narrow separation between large
areas of conductor; hence capacitor conductors are often called "plates," referring to
an early means of construction. In practice, the dielectric between the plates passes a
small amount of leakage current and also has an electric field strength limit, resulting
in a breakdown voltage, while the conductors and leads introduce an undesired
inductance and resistance.
Capacitors are widely used in electronic circuits for blocking direct current while
allowing alternating current to pass, in filter networks, for smoothing the output of
power supplies, in the resonant circuits that tune radios to particular frequencies
and for many other purposes.
A capacitor consists of two conductors separated by a non-conductive region. The

non-conductive region is called the dielectric. In simpler terms, the dielectric is just
an electrical insulator. Examples of dielectric mediums are glass, air, paper, vacuum,
and even a semiconductor depletion region chemically identical to the conductors. A
capacitor is assumed to be self-contained and isolated, with no net electric charge
and no influence from any external electric field. The conductors thus hold equal and
opposite charges on their facing surfaces, and the dielectric develops an electric field.

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In SI units, a capacitance of one farad means that one coulomb of charge on each
conductor causes a voltage of one volt across the device.
The capacitor is a reasonably general model for electric fields within electric
circuits. An ideal capacitor is wholly characterized by a constant capacitance C,
defined as the ratio of charge ±Q on each conductor to the voltage V between them:

C

Q
V

DIODE
A diode is a type of two-terminal electronic component with nonlinear resistance
and conductance (i.e., a nonlinear current–voltage characteristic), distinguishing it
from components such as two-terminal linear resistors which obey Ohm's law. A
semiconductor diode, the most common type today, is a crystalline piece of
semiconductor material connected to two electrical terminals. A vacuum tube diode
(now rarely used except in some high-power technologies) is a vacuum tube with

two electrodes: a plate and a cathode.
The most common function of a diode is to allow an electric current to pass in one
direction (called the diode's forward direction), while blocking current in the
opposite direction (the reverse direction). Thus, the diode can be thought of as an
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electronic version of a check valve. This unidirectional behavior is called
rectification, and is used to convert alternating current to direct current, and to
extract modulation from radio signals in radio receivers—these diodes are forms of
rectifiers.

A Zener diode is a special kind of diode which allows current to flow in the
forward direction in the same manner as an ideal diode, but will also permit it to flow
in the reverse direction when the voltage is above a certain value known as the
breakdown voltage, "Zener knee voltage" or "Zener voltage." The device was named
after Clarence Zener, who discovered this electrical property. A Zener diode exhibits
almost the same properties, except the device is specially designed so as to have a
greatly reduced breakdown voltage, the so-called Zener voltage. By contrast with the
conventional device, a reverse-biased Zener diode will exhibit a controlled
breakdown and allow the current to keep the voltage across the Zener diode close to
the Zener breakdown voltage. For example, a diode with a Zener breakdown voltage
of 3.2 V will exhibit a voltage drop of very nearly 3.2 V across a wide range of reverse
currents. The Zener diode is therefore ideal for applications such as the generation of
a reference voltage (e.g. for an amplifier stage), or as a voltage stabilizer for lowcurrent applications.

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A diode bridge is an arrangement of four (or more) diodes in a bridge circuit
configuration that provides the same polarity of output for either polarity of input.
When used in its most common application, for conversion of an alternating current
(AC) input into direct current a (DC) output, it is known as a bridge rectifier. A
bridge rectifier provides full-wave rectification from a two-wire AC input, resulting in
lower cost and weight as compared to a rectifier with a 3-wire input from a
transformer with a center-tapped secondary winding.
The essential feature of a diode bridge is that the polarity of the output is the
same regardless of the polarity at the input. The diode bridge circuit is also known as
the Graetz circuit after its inventor, physicist Leo Graetz.

HW: Describing the basic operation of Diode Bridge?

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LIGHT EMITTING DIODE
A light-emitting diode (LED) is a semiconductor light source. LEDs are used as
indicator lamps in many devices and are increasingly used for other lighting.
Introduced as a practical electronic component in 1962, early LEDs emitted lowintensity red light, but modern versions are available across the visible, ultraviolet,
and infrared wavelengths, with very high brightness.
When a light-emitting diode is forward-biased (switched on), electrons are able to
recombine with electron holes within the device, releasing energy in the form of
photons. This effect is called electroluminescence and the color of the light
(corresponding to the energy of the photon) is determined by the energy gap of the

semiconductor. LEDs are often small in area (less than 1 mm2), and integrated optical
components may be used to shape its radiation pattern. LEDs present many
advantages over incandescent light sources including lower energy consumption,
longer lifetime, improved robustness, smaller size, and faster switching. LEDs
powerful enough for room lighting are relatively expensive and require more precise
current and heat management than compact fluorescent lamp sources of comparable
output.
Light-emitting diodes are used in applications as diverse as replacements for
aviation lighting, automotive lighting (in particular brake lamps, turn signals, and
indicators) as well as in traffic signals. LEDs have allowed new text, video displays,
and sensors to be developed, while their high switching rates are also useful in
advanced communications technology. Infrared LEDs are also used in the remote
control units of many commercial products including televisions, DVD players, and
other domestic appliances.

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A seven-segment display (SSD), or seven-segment indicator, is a form of
electronic display device for displaying decimal numerals that is an alternative to the
more complex dot-matrix displays. Seven-segment displays are widely used in digital
clocks, electronic meters, and other electronic devices for displaying numerical
information.

A seven segment display, as its name indicates, is composed of seven elements.
Individually on or off, they can be combined to produce simplified representations of
the Arabic numerals. Often the seven segments are arranged in an oblique (slanted)
arrangement, which aids readability. In most applications, the seven segments are of

nearly uniform shape and size (usually elongated hexagons, though trapezoids and
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rectangles can also be used), though in the case of adding machines, the vertical
segments are longer and more oddly shaped at the ends in an effort to further
enhance readability.
In a simple LED package, typically all of the cathodes (negative terminals) or all of
the anodes (positive terminals) of the segment LEDs are connected and brought out
to a common pin; this is referred to as a "common cathode" or "common anode"
device. Hence a 7-segment plus decimal point package will only require nine pins
(though commercial products typically contain more pins, and/or spaces where pins
would go, in order to match industry standard pinouts).
Integrated displays also exist, with single or multiple digits. Some of these
integrated displays incorporate their own internal decoder, though most do not –
each individual LED is brought out to a connecting pin as described. Multiple-digit
LED displays as used in pocket calculators and similar devices used multiplexed
displays to reduce the number of IC pins required to control the display. For example,
all the anodes of the A segments of each digit position would be connected together
and to a driver pin, while the cathodes of all segments for each digit would be
connected. To operate any particular segment of any digit, the controlling integrated
circuit would turn on the cathode driver for the selected digit, and the anode drivers
for the desired segments; then after a short blanking interval the next digit would be
selected and new segments lit, in a sequential fashion. Often in pocket calculators the
digit drive lines would be used to scan the keyboard as well, providing further
savings; however, pressing multiple keys at once would produce odd results on the
multiplexed display.

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An LED matrix or LED display is a large, low-resolution form of dot matrix
display, useful both for industrial and commercial information displays as well as for
hobbyist human–machine interfaces. It consists of a 2-D matrix of LEDs with their
cathodes joined in rows and their anodes joined in columns (or vice versa). By
controlling the flow of electricity through each row and column pair it is possible to
control each LED individually. By scanning across rows, quickly flashing the LEDs on
and off, it is possible to create characters or pictures to display information to the
user. By varying the pulse rate per LED, the display can approximate levels of
brightness. Multi-colored LEDs or RGB-colored LEDs permit use as a full-color image
display. The refresh rate is typically fast enough to prevent the human eye from
detecting the flicker.
A dot matrix display is a display device used to display information on machines,
clocks, railway departure indicators and many other devices requiring a simple
display device of limited resolution. The display consists of a matrix of lights or
mechanical indicators arranged in a rectangular configuration (other shapes are also
possible, although not common) such that by switching on or off selected lights, text
or graphics can be displayed. A dot matrix controller converts instructions from a
processor into signals which turns on or off lights in the matrix so that the required
display is produced.

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BIPOLAR JUNCTION TRANSISTOR (BJT)
A bipolar junction transistor (BJT) is a three-terminal electronic device
constructed of doped semiconductor material and may be used in amplifying or
switching applications. Bipolar transistors are so named because their operation
involves both electrons and holes. Charge flow in a BJT is due to bidirectional
diffusion of charge carriers across a junction between two regions of different charge
concentrations. This mode of operation is contrasted with unipolar transistors, such
as field-effect transistors, in which only one carrier type is involved in charge flow
due to drift. By design, most of the BJT collector current is due to the flow of charges
injected from a high-concentration emitter into the base where they are minority
carriers that diffuse toward the collector, and so BJTs are classified as minoritycarrier devices.

NPN TYPE
NPN is one of the two types of bipolar transistors, consisting of a layer of P-doped
semiconductor (the "base") between two N-doped layers. A small current entering
the base is amplified to produce a large collector and emitter current. That is, an NPN
transistor is "on" when its base is pulled high relative to the emitter.
Most of the NPN current is carried by electrons, moving from emitter to collector
as minority carriers in the P-type base region. Most bipolar transistors used today
are NPN, because electron mobility is higher than hole mobility in semiconductors,
allowing greater currents and faster operation. A mnemonic device for the
remembering the symbol for an NPN transistor is not pointing in, based on the
arrows in the symbol and the letters in the name. That is, the NPN transistor is the
BJT transistor that is "not pointing in".

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PNP TYPE
The other type of BJT is the PNP, consisting of a layer of N-doped semiconductor
between two layers of P-doped material. A small current leaving the base is amplified
in the collector output. That is, a PNP transistor is "on" when its base is pulled low
relative to the emitter.
The arrows in the NPN and PNP transistor symbols are on the emitter legs and
point in the direction of the conventional current flow when the device is in forward
active mode.
A mnemonic device for the remembering the symbol for a PNP transistor is
pointing in (proudly), based on the arrows in the symbol and the letters in the name.
That is, the PNP transistor is the BJT transistor that is "pointing in".

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