Final Rebasiport (the Correct One)

7/30/2019 Final Rebasiport (the Correct One)

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ONE MONTH TRAINING REPORT

In the partial fulfillment of the degree of Bachelor of Technologyin Electronics and Communication engineering.

Submitted To: Submitted By:90640415486

RIMT - INSTITUTE OF ENGINEERING & TECHNOLOGY,

MANDI GOBINDGARH


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CONTENTS

1. INTRODUCTION TO ELECTRONIC COMPONENTS 6

2. RESISTORS 7FIXED RESISTORS 7

CARBON FILM RESISTORS 7METAL FILM RESISTORS 7

2.2. VARIABLE RESISTORS 82.3. RESISTOR COLOR CODE 9

3. CAPACITORS 11

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ELECTROLYTIC CAPACITORS 11CERAMIC CAPACITORS 12MULTI LAYER CERAMIC CAPACITORS 13MICA CAPACITORS 13VARIABLE CAPACITORS 13

4. DIODES 15RECTIFICATION / SWITCHING / REGULATION DIODE 16LIGHT EMITTING DIODE 17SHOTTKY BARRIER DIODE 18

5. TRANSISTORS 19SIMPLIFIED OPERATION 19TRANSISTOR AS ASWITCH 20TRANSISTOR AS AN AMPLIFIER 21TYPES OF TRANSISTORS 21

BIPOLAR JUNCTION TRANSISTOR 21FIELD EFFECT TRANSISTOR 22

6. INTRODUCTION TO INTEGRATED CIRCUITS 23

THREE TERMINAL VOLTAGE REGULATOR 23

7. MULTIMETER 25USES OF MULTIMETER 25ACCURACY 26

8. CATHODE RAY OSCILLOSCOPE 27

PROJECT REPORT 30

SEMINAR REPORT 32

LIST OF FIGURES

1. CARBON FILM RESISTORS 72. METAL FILM RESISTOR 83. VARIABLE RESISTOR 84. ELECTROLYTIC CAPACITORS 125. CERAMIC CAPACITORS 126. MULTI LAYER CERAMIC CAPACITORS 137. MICA CAPACITORS 138. VARIABLE CAPACITORS FOR DIFFERENT SPECIFICATIONS 14

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9. REGULATION DIODES 1610. LIGHT EMITTING DIODES OF DIFFERENT COLORS 1711. SHOTTKY BARRIER DIODE 1812. SIMPLIFIED OPERATION OF TRANSISTOR 1913. TRANSISTOR AS A SWITCH 20

14. TRANSISTOR AS AMPLIFIER 2115. STRUCTURE OF ICS 2316. THREE TERMINAL VOLTAGE REGULATOR 2317. MULTIMETER 2518. .CATHODE RAY OSCILLOSCOPE 27

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1. INTRODUCTION: ELECTRONICS COMPONENTS

An electronic component is any physical entity in an electronic system whose intention is to

affect the electrons or their associated fields in a desired manner consistent with the intendedfunction of the electronic system. Co mponents are generally intended to be in mutualelectromechanical contact, usually by being soldered to a printed circuit board (PCB), to createan electronic circuit with a particular function (for example an amplifier, radio receiver, or oscillator). Components may be packaged singly or in more or less complex groups as integratedcircuits. Various components and devices are described below.

ACTIVE COMPONENTS

Active components increase the power of a signal and must be supplied with the signal and asource of power. The signal is fed into one connection of the active device and the amplifiedversion taken from another connection.

PASSIVE COMPONENTS

Passive components do not increase the power of a signal. They often cause power to be lost.Some can increase the voltage at the expense of current, so overall there is loss of power.

Resistors, Capacitors, Inductors & Diodes are the examples of passive components.

2. RESISTORS

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The resistor's function is to reduce the flow of electric current. This symbol isused to indicate a resistor in a circuit diagram, known as a schematic. Resistance value isdesignated in units called the "Ohm." A 1000 Ohm resistor is typically shown as 1K-Ohm (kilo Ohm), and 1000 K-Ohms is written as 1M-Ohm (megohm).

There are two classes of resistors; fixed resistors and the variable resistors. They are alsoclassified according to the material from which they are made. The typical resistor ismade of either carbon film or metal film. There are other types as well, but these are themost common.The resistance value of the resistor is not the only thing to consider whenselecting a resistor for use in a circuit. The "tolerance" and the electric power ratings of the resistor are also important.The tolerance of a resistor denotes how close it is to theactual rated resistence value. For example, a 5% tolerance would indicate a resistor thatis within 5% of the specified resistance value.The power rating indicates how much

power the resistor can safely tolerate. Just like you wouldn't use a 6 volt flashlight lampto replace a burned out light in your house, you wouldn't use a 1/8 watt resistor when

you should be using a 1/2 watt resistor.

2.1 FIXED RESISTORS

A fixed resistor is one in which the value of its resistance cannot change.

2.1.1CARBON FILM RESISTORSThis is the most general purpose, cheap resistor. Usually the tolerance of the resistancevalue is 5%. Power ratings of 1/8W, 1/4W and 1/2W are frequently used.Carbon filmresistors have a disadvantage; they tend to be electrically noisy. Metal film resistors arerecommended for use in analog circuits. However, I have never experienced any

problems with this noise.The physical size of the different resistors is as follows.

2.1.2 METAL FILM RESISTORSMetal film resistors are used when a higher tolerance (more accurate value) is needed.They are much more accurate in value than carbon film resistors. They have about0.05% tolerance. They have about 0.05% tolerance. I don't use any high toleranceresistors in my circuits. Resistors that are about 1% are more than sufficient. Ni-Cr (Nichrome) seems to be used for the material of resistor. The metal film resistor is usedfor bridge circuits, filter circuits, and low-noise analog signal circuits.

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2.2 VARIABLE RESISTORS

There are two general ways in which variable resistors are used. One is the variableresistor which value is easily changed, like the volume adjustment of Radio. The other issemi-fixed resistor that is not meant to be adjusted by anyone but a technician. It is usedto adjust the operating condition of the circuit by the technician. Semi-fixed resistors areused to compensate for the inaccuracies of the resistors, and to fine-tune a circuit. Therotation angle of the variable resistor is usually about 300 degrees. Some variableresistors must be turned many times to use the whole range of resistance they offer. Thisallows for very precise adjustments of their value. These are called "Potentiometers" or "Trimmer Potentiometers."

The variable resistor typically used for volume controls can be seen on the far right. Itsvalue is very easy to adjust. The four resistors at the center of the photograph are thesemi-fixed type. These ones are mounted on the printed circuit board. The two resistorson the left are the trimmer potentiometers.

This symbol is used to indicate a variable resistor in a circuit diagram.

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There are three ways in which a variable resistor's value can change according to therotation angle of its axis. When type "A" rotates clockwise, at first, the resistance valuechanges slowly and then in the second half of its axis, it changes very quickly. The "A"type variable resistor is typically used for the volume control of a radio, for example. Itis well suited to adjust a low sound subtly. It suits the characteristics of the ear. The ear hears low sound changes well, but isn't as sensitive to small changes in loud sounds. Alarger change is needed as the volume is increased. These "A" type variable resistors aresometimes called "audio taper" potentiometers. As for type "B", the rotation of the axisand the change of the resistance value are directly related. The rate of change is thesame, or linear, throughout the sweep of the axis. This type suits a resistance valueadjustment in a circuit, a balance circuit and so on. They are sometimes called "linear taper" potentiometers. Type "C" changes exactly the opposite way to type "A". In theearly stages of the rotation of the axis, the resistance value changes rapidly, and in thesecond half, the change occurs more slowly. This type isn't too much used. It is a specialuse. As for the variable resistor, most are type "A" or type "B".

2.3 RESISTOR COLOR CODE

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Color Value Multiplier Tolerance(%)

Black 0 0 -

Brown 1 1 1

Red 2 2 2

Orange 3 3 0.05

Yellow 4 4 -

Green 5 5 0.5

Blue 6 6 0.25

Violet 7 7 0.1

Gray 8 8 -White 9 9 -

Gold - -1 5

Silver - -2 10

None - - 20

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3. CAPACITORS

The capacitor's function is to store electricity, or electrical energy.The capacitor also functions as a filter, passing alternating current (AC), and blockingdirect current (DC).This symbol is used to indicate a capacitor in a circuit diagram.The capacitor is constructed with two electrode plates facing each other, but separated

by an insulator.

When DC voltage is applied to the capacitor, an electric charge is stored on eachelectrode. While the capacitor is charging up, current flows. The current will stopflowing when the capacitor has fully charged. The value of a capacitor (the capacitance),is designated in units called the Farad ( F ).The capacitance of a capacitor is generallyvery small, so units such as the microfarad ( 10 -6F ), Nano farad ( 10 -9F ), and Pico farad(10 -12F ) are used. Recently, a new capacitor with very high capacitance has beendeveloped. The Electric Double Layer capacitor has capacitance designated in Faradunits. These are known as "Super Capacitors.

Sometimes, a three-digit code is used to indicate the value of a capacitor. There are twoways in which the capacitance can be written. One uses letters and numbers, the other uses only numbers. In either case, there are only three characters used. [10n] and [103]denote the same value of capacitance. The method used differs depending on thecapacitor supplier. In the case that the value is displayed with the three-digit code, the1st and 2nd digits from the left show the 1st figure and the 2nd figure, and the 3rd digitis a multiplier which determines how many zeros are to be added to the capacitance.Picofarad (pF) units are written this way.

3.1. ELECTROLYTIC CAPACITORS

Aluminum is used for the electrodes by using a thin oxidization membrane.Large values of capacitance can be obtained in comparison with the size of the capacitor,

because the dielectric used is very thin. The most important characteristic of electrolyticcapacitors is that they have polarity. They have a positive and a negative electrode.[Polarized] This means that it is very important which way round they are connected . If the capacitor is subjected to voltage exceeding its working voltage, or if it is connectedwith incorrect polarity, it may burst. It is extremely dangerous, because it can quiteliterally explode. Make absolutely no mistakes . Generally, in the circuit diagram, the

positive side is indicated by a "+" (plus) symbol. Electrolytic capacitors range in valuefrom about 1F to thousands of F. mainly this type of capacitor is used as a ripple filter in a power supply circuit, or as a filter to bypass low frequency signals, etc. Because thistype of capacitor is comparatively similar to the nature of a coil in construction, it isn't

possible to use for high-frequency circuits. (It is said that the frequency characteristic is bad.)

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From the left to right:1F (50V) [diameter 5 mm, high 12 mm]47F (16V) [diameter 6 mm, high 5 mm]

100F(25V)[diameter 5 mm, high 11 mm]220F (25V) [diameter 8 mm, high 12 mm]1000F (50V) [diameter 18 mm, high 40 mm]The size of the capacitor sometimes depends on the manufacture.

3.2. CERAMIC CAPACITORS

Ceramic capacitors are constructed with materials such as titanium acid barium used asthe dielectric. Internally, these capacitors are not constructed as a coil, so they can be

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used in high frequency applications. Typically, they are used in circuits which bypasshigh frequency signals to ground. These capacitors have the shape of a disk. Their capacitance is comparatively small.The capacitor on the left is a 100pF capacitor with a diameter of about 3 mm. Thecapacitor on the right side is printed with 103, so 10 x 10 3 pF becomes 0.01 F. The

diameter of the disk is about 6 mm. Ceramic capacitors have no polarity. Ceramiccapacitors should not be used for analog circuits, because they can distort the signal.

3.3. MULTI LAYER CERAMIC CAPACITORS

The multilayer ceramic capacitor has a many-layereddielectric. These capacitors are small in size, and have goodtemperature and frequency characteristics.Square wave signals used in digital circuits can have

a comparatively high frequency component included. Thiscapacitor is used to bypass the high frequency to ground.In the photograph, the capacitance of the component on theleft is displayed as 104. So, the capacitance is 10 x 10 4 pF =0.1 F. The thickness is 2 mm, the height is 3 mm, and thewidth is 4 mm. The capacitor to the right has a capacitanceof 103 (10 x 10 3 pF = 0.01 F). The height is 4 mm; thediameter of the round part is 2 mm.

These capacitors are not polarized. That is, they have no polarity.

3.4. MICA CAPACITORS

These capacitors use Mica for the dielectric. Mica capacitors have good stability becausetheir temperature coefficient is small.Because their frequency characteristicis excellent, they are used for resonance circuits, and high frequencyfilters. Also, they have goodinsulation, and so can be utilized in

high voltage circuits. It was often used for vacuum tube style radio transmitters, etc.Mica capacitors do not have high values of capacitance, and they can be relativelyexpensive.

Pictured above are "Dipped mica capacitors." These can handle up to 500 volts. Thecapacitance from the left .Capacitance: 47pF (printed with 70J) [the width 7mm, theheight 5mm, the thickness 4mm] Capacitance: 220pF (printed with 221J) [the width10mm, the height 6mm, the thickness 4mm] Capacitance: 1000pF (printed with 102J)[the width 14mm, the height 9mm, the thickness 4mm] These capacitors have no

polarity.

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3.5. VARIABLE CAPACITORS

Variable capacitors are used for adjustment etc. of frequency mainly.On the left in the photograph is a "trimmer," which uses ceramic as the dielectric. Nextto it on the right is one that uses polyester film for the dielectric. The pictured

components are meant to be mounted on a printed circuit board.When adjusting the value of a variable capacitor, it is advisable to be careful.One of the component's leads is connected to the adjustment screw of the capacitor. Thismeans that the value of the capacitor can be affected by the capacitance of thescrewdriver in your hand. It is better to use a special screwdriver to adjust thesecomponents.

Pictured in the above photograph are variable capacitors with the followingspecifications:Capacitance: 20pF (3pF - 27pF measured) [Thickness 6 mm, height 4.8 mm]Their are different colors, as well. Blue: 7pF (2 - 9), white: 10pF (3 - 15), green: 30pF (5- 35), brown: 60pF (8 - 72).In the same photograph, the device on the right has the following specifications:Capacitance: 30pF (5pF - 40pF measured) [The width (long) 6.8 mm, width (short) 4.9mm, and the height 5 mm]

The components in the photograph are used for radio tuners, etc. They are called"Varicons" but this may be only in Japan. The variable capacitor on the left in the

photograph uses air as the dielectric. It combines three independent capacitors. For eachone, the capacitance changed 2pF - 18pF. When the adjustment axis is turned, thecapacitance of all 3 capacitors change simultaneously. Physically, the device has a depthof 29 mm, and 17 mm width and height. (Not including the adjustment rod.)There are various kinds of variable capacitor, chosen in accordance with the purpose for which they are needed. The pictured components are very small.

To the right in the photograph is a variable capacitor using polyester film as the

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dielectric. Two independent capacitors are combined. The capacitance of one sidechanges 12pF - 150pF, while the other side changes from 11pF - 70pF. Physically, it hasa depth of 11mm, and 20mm width and height. (Not including the adjustment rod.) The

pictured device also has a small trimmer built in to each capacitor to allow.

4. DIODES

A diode is a semiconductor device which allows current to flow through it in only onedirection. Although a transistor is also a semiconductor device, it does not operate theway a diode does. A diode is specifically made to allow current to flow through it inonly one direction.Some ways in which the diode can be used are listed here.

A diode can be used as a rectifier that converts AC (Alternating Current) to DC(Direct Current) for a power supply device.

Diodes can be used to separate the signal from radio frequencies. Diodes can be used as an on/off switch that controls current. This symbol

is used to indicate a diode in a circuit diagram.

The meaning of the symbol is (Anode) (Cathode).Current flows fromThe anode side.

Although all diodes operate with the same general principle, there are different typessuited to different applications. For example, the following devices are best used for theapplications noted.

Voltage regulation diode (Zener Diode)

The circuit symbol is.It is used to regulate voltage, by taking advantage of the fact that Zener diodes tend tostabilize at a certain voltage when that voltage is applied in the opposite direction.

Light emitting diode

The circuit symbol is.This type of diode emits light when current flows through it in the forward direction.(Forward biased.)

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Variable capacitance diode

The circuit symbol is.The current does not flow when applying the voltage of the opposite direction to thediode. In this condition, the diode has a capacitance like the capacitor. It is a very smallcapacitance. The capacitance of the diode changes when changing voltage. With thechange of this capacitance, the frequency of the oscillator can be changed.

The graph shows the electrical characteristics of a typical diode.

When a small voltage is applied to the diode in the forward direction, current flowseasily. Because the diode has acertain amount of resistance, thevoltage will drop slightly ascurrent flows through the diode.

A typical diode causes a voltagedrop of about 0.6 - 1V (V F) (Inthe case of silicon diode, almost0.6V) this voltage drop needs to

be taken into consideration in acircuit which uses many diodesin series. Also, the amount of current passing through thediodes must be considered.

When voltage is applied in the

reverse direction through adiode, the diode will have a great resistance to current flow.Different diodes have different characteristics when reverse-biased. A given diodeshould be selected depending on how it will be used in the circuit.The current that will flow through a diode biased in the reverse direction will vary fromseveral mA to just A, which is very small.The limiting voltages and currents permissible must be considered on a case by case

basis. For example, when using diodes for rectification, part of the time they will berequired to withstand a reverse voltage. If the diodes are not chosen carefully, they will

break down.

4.1. RECTIFICATION / SWITCHING / REGULATION DIODE

The stripe stamped on one end of the diodeshows indicates the polarity of the diode.

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The stripe shows the cathode side. The top two devices shown in the picture are diodesused for rectification. They are made to handle relatively high currents. The device ontop can handle as high as 6A, and the one below it can safely handle up to 1A. However,it is best used at about 70% of its rating because this current value is a maximum rating.The third device from the top (red color) has a part number of 1S1588. This diode is

used for switching, because it can switch on and off at very high speed. However, themaximum current it can handle is 120 mA. This makes it well suited to use withindigital circuits. The maximum reverse voltage (reverse bias) this diode can handle is30V. The device at the bottom of the picture is a voltage regulation diode with a ratingof 6V. When this type of diode is reverse biased, it will resist changes in voltage. If theinput voltage is increased, the output voltage will not change. (Or any change will be aninsignificant amount.) While the output voltage does not increase with an increase ininput voltage, the output current will. This requires some thought for a protection circuitso that too much current does not flow. The rated current limit for the device is 30 mA.Generally, a 3-terminal voltage regulator is used for the stabilization of a power supply.Therefore, this diode is typically used to protect the circuit from momentary voltage

spikes. 3 terminal regulators use voltage regulation diodes inside.

4.2. LIGHT EMITTING DIODE

Light emitting diodes must be chosen according to how they will be used, because thereare various kinds. The diodes areavailable in several colors. Themost common colors are red andgreen, but there are even blueones.

The device on the far right in the photograph combines a red LEDand green LED in one package.The component lead in themiddle is common to bothLEDs. As for the remaing two

leads, one side is for the green, the other for the red LED. When both are turned onsimultaneously, it becomes orange.

When an LED is new out of the package, the polarity of the device can be determined bylooking at the leads. The longer lead is the Anode side, and the short one is the Cathode

side.

The polarity of an LED can also be determined using a resistance meter, or even a 1.5 V battery.When using a test meter to determine polarity, set the meter to a low resistancemeasurement range. Connect the probes of the meter to the LED. If the polarity iscorrect, the LED will glow. If the LED does not glow, switch the meter probes to theopposite leads on the LED. In either case, the side of the diode which is connected to the

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black meter probe when the LED glows, is the Anode side. Positive voltage flows out of the black probe when the meter is set to measure resistance.

4.3. SHOTTKY BARRIER DIODEDiodes are used to rectify alternating current into directcurrent. However, rectification will not occur when thefrequency of the alternating current is too high. This is due towhat is known as the "reverse recovery characteristic." Thereverse recovery characteristic can be explained as follows: IFthe opposite voltage is suddenly applied to a forward-biased

diode, current will continue to flow in the forward direction for a brief moment. This time until the current stops flowing iscalled the Reverse Recovery Time. The current is considered to

be stopped when it falls to about 10% of the value of the peak reverse current. TheShottky barrier diode has a short reverse recovery time, which makes it ideally suited touse in high frequency rectification.

The shottky barrier diode has the following characteristics.The voltage drop in the forward direction is low.The reverse recovery time is short.

However, it has the following disadvantages.The diode can have relatively high leakage current.The surge resistance is low.

Because the reverse recovery time is short, this diode is often used for the switchingregulator in a high frequency circuit.

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5. TRANSISTORS

A transistor is a semiconductor device used to amplify and switch electronic signals. It ismade of a solid piece of semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the

transistor's terminals changes the current flowing through another pair of terminals.Because the controlled (output) power can be much more than the controlling (input) power, the transistor provides amplification of a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

The transistor is the fundamental building block of modern electronic devices, and its presence is ubiquitous in modern electronic systems.

The transistor is the key active component in practically all modernelectronics, and is considered by many to be one of the greatest inventionsof the twentieth century. Its importance in today's society rests on

it ability to be mass produced using a highly automated process (semiconductor deviceFabrication) that achieves astonishingly low per-transistor costs.

Although several companies each produce over a billion individually packaged (knownas discrete) transistors every year, the vast majority of transistors now produced arein integrated circuits (often shortened to IC, microchips or simply chips), alongwith diodes , resistors , capacitors and other electronic components to produce completeelectronic circuits. A logic gate consists of up to about twenty transistors whereas anadvanced microprocessor, as of 2009, can use as many as 2.3 billion transistors(MOSFETs)

5.1. SIMPLIFIED OPERATION

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.The essential usefulness of a transistor comes from its ability to use a small signalapplied between one pair of its terminals to control a much larger signal at another pair of terminals. This property is called gain. A transistor can control its output in

proportion to the input signal, that is, can act as an amplifier. Alternatively, the transistor

can be used to turn current on or off in a circuit as an electrically controlled switch,where the amount of current is determined by other circuit elements.The two types of transistors have slight differences in how they are used in a circuit.A bipolar transistor has terminals labeled base, collector, and emitter. A small current atthe base terminal (that is, flowing from the base to the emitter) can control or switch amuch larger current between the collector and emitter terminals. For a field-effecttransistor, the terminals are labeled gate, source, and drain, and a voltage at the gate cancontrol a current between source and drain.The image to the right represents a typical bipolar transistor in a circuit. Charge willflow between emitter and collector terminals depending on the current in the base. Sinceinternally the base and emitter connections behave like a semiconductor diode, a voltage

drop develops between base and emitter while the base current exists. The amount of this voltage depends on the material the transistor is made from, and is referred to as V BE.5.2. TRANSISTOR AS A SWITCH

BJT used as an electronic switch, in grounded-emitter configuration.Transistors are commonly used as electronic switches, for both high power applicationsincluding switched-mode power supplies and low power applications such as logicgates.

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In a grounded-emitter transistor circuit, such as the light-switch circuit shown, as the base voltage raises the base and collector current rise exponentially, and the collector voltage drops because of the collector load resistor. The relevant equations:VRC = I CE R C, the voltage across the load (the lamp with resistance R C)VRC + V CE = V CC, the supply voltage shown as 6V

If V CE could fall to 0 (perfect closed switch) then IC could go no higher than V CC / R C,even with higher base voltage and current. The transistor is then said to be saturated.Hence, values of input voltage can be chosen such that the output is either completelyoff, or completely on. The transistor is acting as a switch, and this type of operation iscommon in digital circuits where only "on" and "off" values are relevant.

5.3. TRANSISTOR AS AN AMPLIFIER

Amplifier circuit, standard common-emitter configuration.

The common-emitter amplifier is designed so that asmall change in voltage in (V in) changes the small current through the base of thetransistor and the transistor's current amplification combined with the properties of thecircuit mean that small swings in V in produce large changes in V out.

Various configurations of single transistor amplifier are possible, with some providing

current gain, some voltage gain, and some both.

From mobile phones to televisions , vast numbers of products include amplifiers

for sound reproduction , radio transmission, and signal processing . The first discrete

transistor audio amplifiers barely supplied a few hundred mill watts, but power and

audio fidelity gradually increased as better transistors became available and amplifier

architecture evolved.

Modern transistor audio amplifiers of up to a few hundred watts are common andrelatively inexpensive.

5.4. TYPES OF TRANSISTORS

5.4.1. BIPOLAR JUNCTION TRANSISTOR

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Bipolar transistors are so named because they conduct by using both majority andminority carriers. The bipolar junction transistor (BJT), the first type of transistor to bemass-produced, is a combination of two junction diodes, and is formed of either a thinlayer of p-type semiconductor sandwiched between two n-type semiconductors (an n-p-ntransistor), or a thin layer of n-type semiconductor sandwiched between two p-type

semiconductors (a p-n-p transistor). This construction produces two p-n junctions: a baseemitter junction and a basecollector junction, separated by a thin region of semiconductor known as the base region (two junction diodes wired together withoutsharing an intervening semi conducting region will not make a transistor).The BJT has three terminals, corresponding to the three layers of semiconductor -an emitter, abase, and a collector. It is useful in amplifiers because the currents at theemitter and collector are controllable by a relatively small base current. In an NPNtransistor operating in the active region, the emitter-base junction is forward biased(electrons and holes recombine at the junction), and electrons are injected into the baseregion. Because the base is narrow, most of these electrons will diffuse into the reverse-

biased (electrons and holes are formed at, and move away from the junction) base-

collector junction and be swept into the collector; perhaps one-hundredth of theelectrons will recombine in the base, which is the dominant mechanism in the basecurrent. By controlling the number of electrons that can leave the base, the number of electrons entering the collector can be controlled. Collector current is approximately (common-emitter current gain) times the base current. It is typically greater than 100 for small-signal transistors but can be smaller in transistors designed for high-power applications.

5.4.2. FIELD EFFECT TRANSISTOR

The field-effect transistor (FET) relies on an electric field to control the shape and hence

the conductivity of a channel of one type of charge carrier in a semiconductor material.FETs are sometimes called unipolar transistors to contrast their single-carrier-typeoperation with the dual-carrier-type operation of bipolar (junction) transistors (BJT).The concept of the FET predates the BJT, though it was not physically implementeduntil after BJTs due to the limitations of semiconductor materials and the relative ease of manufacturing BJTs compared to FETs at the time .

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6. INTRODUCTION TO INTEGRATED CIRCUITS

An integrated circuit contains transistors, capacitors, resistors and other parts packed inhigh density on one chip. Although the function is similar to a circuit made with separatecomponents, the internal structure of the components are different in an integratedcircuit.The transistors, resistors, and capacitors are formed very small, and in high density on afoundation of silicon. They are formed by a variation of printing technology.There are many kind of ICs, including special use ICs.

The top left device in the photograph is an SN7400. It contains 4 separate "2 input NAND" circuits. There are 7 pins on each side, 14 pins total.

ICs in this form are called DualIn line Package (DIP).When an IC has only one rowof pins, it so called a Single inline Package (SIP). The number of pins changes depending onthe function of IC.

At the bottom left is an ICsocket for use with 14 pin DIPICs.

ICs can be attached directly tothe printed circuit board withsolder, but it's better to use anIC socket, because you caneasily exchange it should the IC

fail.

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On the top right is an LM386N audio amplifier. It can be used for amplification of lowfrequency, low power signals. IT has 8 pins and the maximum output is 660mW.

On the bottom right is a TA7368P, which also is for amplification of low frequencyelectric power. It has a maximum output of 1.1 watts

6.1. THREE TERMINAL VOLTAGE REGULATORS

It is very easy to get stabilized voltage for ICs byusing a three terminal voltage regulator.The power supply voltage for a car is +12V - +14V.At this voltage, some ICs can not operate directlyexcept for the car component ICs. In this case, a threeterminal voltage regulator is necessary to get therequired voltage.The three terminal voltage regulator outputs stabilized

voltage at a lower level than the higher input voltage.A voltage regulator cannot put out higher voltage thanthe input voltage. They are similar in appearance to a

transistor.

On the left in the photograph is a 78L05. The size and form is similar to a 2SC1815transistor.The output voltage is +5V, and the maximum output current is about 100mA.The maximum input voltage is +35V. (Differs by manufacturer).

On the right is a 7805. The output voltage is +5V, and maximum output current is

500mA to 1A. (It depends on the heat sink used)The maximum input voltage is also +35V. There are many types with different outputvoltages.5V, 6V, 7V, 8V, 9V, 10V, 12V, 15V, 18V.

Integrated circuits were made possible by experimental discoveries which showedthat semiconductor devices could perform the functions of vacuum tubes and by mid-20th-century technology advancements in semiconductor device fabrication . Theintegration of large numbers of transistors into a small chip was an enormousimprovement over the manual assembly of circuits using electronic components . The

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integrated circuit's mass production capability, reliability, and building-block approachto circuit design ensured the rapid adoption of standardized ICs in place of designs usingdiscrete transistors.

7. MULTIMETER A multimeter or also known as a volt/ohm meter or VOM, is an electronic measuring instrument that combines several measurement functions in one unit. A typicalmultimeter may include features such as the ability tomeasure voltage , current and resistance. There are two categories of multimeters, analogmultimeters and digital multimeters (often abbreviated DMM or DVOM.)

A multimeter can be a hand-held device useful for basic fault finding and field servicework or a bench instrument which can measure to a very high degree of accuracy. Theycan be used to troubleshoot electrical problems in a wide array of industrial andhousehold devices such as batteries , motor controls, appliances, power supplies , andwiring systems.

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7.1. USES OF MULTIMETER

Contemporary multimeters can measure many quantities. The common ones are:

Voltage in volts.Current in amperes.Resistance in ohms.

Additionally, multimeters may also measure:Capacitance in farads.Conductance in Siemens.Decibels.Duty cycle as a percentage.Frequency in hertzInductance in henrysTemperature in degrees Celsius or Fahrenheit.

Digital multimeters may also include circuits for:Continuity that beeps when a circuit conducts.Diodes (measuring forward drop and/or polarity) and transistors (measuringcurrent gain and other parameters)"Battery Check" for simple 1.5 and 9V batteries. This is a current loaded voltagescale. Battery checking can be done less accurately using a DC Voltage scale.

7.2. ACCURACY

Digital multimeters generally take measurements with accuracy superior to their analogcounterparts. Analog multimeters typically measure with about three percent accuracy

Standard portable digital multimeters claim to be capable of taking measurements withan accuracy of 0.5% on the DC voltage ranges. Mainstream bench-top multimeters makeclaims to have an accuracy of better than 0.01%. Laboratory grade instruments canhave accuracies in the parts per million figures.A multimeters quoted accuracy is specified as being that of the lower (mV) DC range,and is known as the "basic DC volts accuracy" figure. Higher DC voltage ranges,current, resistance, AC and other ranges will usually have a lower accuracy than the

basic DC volts figure.

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8. CATHODE RAY OSCILLOSCOPE

The earliest and simplest type of oscilloscope consisted of a cathode ray tube, a verticalamplifier, a timebase, a horizontal amplifier and a power supply. These are now called'analogue' scopes to distinguish them from the 'digital' scopes that became common inthe 1990s and 2000s.

Before the introduction of the CRO in its current form, the cathode ray tube had already been in use as a measuring device. The cathode ray tube is an evacuated glass envelope,similar to that in a black-and-white television set, with its flat face covered in a

phosphorescent material (the phosphor. The screen is typically less than 20 cm indiameter, much smaller than the one in a television set.

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In the neck of the tube is an electron gun, which is a heated metal plate with a wire mesh(the grid) in front of it. A small grid potential is used to block electrons from beingaccelerated when the electron beam needs to be turned off, as during sweep retrace or when no trigger events occur. A potential difference of at least several hundred volts isapplied to make the heated plate (the cathode) negatively charged relative to the

deflection plates. For higher bandwidth oscilloscopes where the trace may move morerapidly across the phosphor target, a positive post-deflection acceleration voltage of over 10,000 volts is often used, increasing the energy (speed) of the electrons that strike the

phosphor. The kinetic energy of the electrons is converted by the phosphor into visiblelight at the point of impact. When switched on, a CRT normally displays a single brightdot in the center of the screen, but the dot can be moved about electrostatically or magnetically. The CRT in an oscilloscope uses electrostatic deflection.

Between the electron gun and the screen are two opposed pairs of metal plates called thedeflection plates. The vertical amplifier generates a potential difference across one pair of plates, giving rise to a vertical electric field through which the electron beam passes.

When the plate potentials are the same, the beam is not deflected.

When the top plate is positive with respect to the bottom plate, the beam is deflectedupwards; when the field is reversed, the beam is deflected downwards. The horizontalamplifier does a similar job with the other pair of deflection plates, causing the beam tomove left or right. This deflection system is called electrostatic deflection, and isdifferent from the electromagnetic deflection system used in television tubes. Incomparison to magnetic deflection, electrostatic deflection can more readily followrandom changes in potential, but is limited to small deflection angles.

The timebase is an electronic circuit that generates a ramp voltage. This is a voltage that

changes continuously and linearly with time. When it reaches a predefined value theramp is reset, with the voltage reestablishing its initial value. When a trigger event isrecognized the reset is released, allowing the ramp to increase again. The timebasevoltage usually drives the horizontal amplifier. Its effect is to sweep the electron beam atconstant speed from left to right across the screen, then quickly return the beam to theleft in time to begin the next sweep. The timebase can be adjusted to match the sweeptime to the period of the signal.

Meanwhile, the vertical amplifier is driven by an external voltage (the vertical input)that is taken from the circuit or experiment that is being measured. The amplifier has avery high input impedance, typically one megohm, so that it draws only a tiny current

from the signal source. The amplifier drives the vertical deflection plates with a voltagethat is proportional to the vertical input. Because the electrons have already beenaccelerated by hundreds of volt, this amplifier also has to deliver almost hundred voltsand this with a very high bandwidth. The gain of the vertical amplifier can be adjusted tosuit the amplitude of the input voltage. A positive input voltage bends the electron beamupwards, and a negative voltage bends it downwards, so that the vertical deflection of the dot shows the value of the input. The response of this system is much faster than that

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of mechanical measuring devices such as the multimeter, where the inertia of the pointer slows down its response to the input.

When all these components work together, the result is a bright trace on the screen thatrepresents a graph of voltage against time. Voltage is on the vertical axis, and time on

the horizontal.

Observing high speed signals, especially non-repetitive signals, with a conventionalCRO is difficult, due to non-stable or changing triggering threshold which makes it hardto "freeze" the waveform on the screen. This often requires the room to be darkened or aspecial viewing hood to be placed over the face of the display tube. To aid in viewingsuch signals, special oscilloscopes have borrowed from night vision technology,employing a microchannel plate in the tube face to amplify faint light signals.

Although a CRO allows one to view a signal, in its basic form it has no means of recording that signal on paper for the purpose of documentation. Therefore, special

oscilloscope cameras were developed to photograph the screen directly. Early camerasused roll or plate film, while in the 1970s Polaroid instant cameras became popular.

The vertical amplifier and timebase controls are calibrated to show the vertical distanceon the screen that corresponds to a given voltage difference, and the horizontal distancethat corresponds to a given time interval.

The power supply is an important component of the scope. It provides low voltages to power the cathode heater in the tube, and the vertical and horizontal amplifiers. Highvoltages are needed to drive the electrostatic deflection plates. These voltages must bevery stable. Any variations will cause errors in the position and brightness of the trace.

Later analogue oscilloscopes added digital processing to the standard design. The same basic architecture - cathode ray tube, vertical and horizontal amplifiers - was retained, but the electron beam was controlled by digital circuitry that could display graphics andtext mixed with the analogue waveforms. The extra features that this system providesinclude:

on-screen display of amplifier and timebase settings; voltage cursors - adjustable horizontal lines with voltage display; time cursors - adjustable vertical lines with time display; On-screen menus for trigger settings and other functions.

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PROJECT REPORTON

MOBILE CELL PHONE CHARGER

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MOBILE CELL PHONE CHARGER

Charging of the cell phone battery is a big problem while traveling as power supply

source is not generally accessible. If you keep your cell phone Switched oncontinuously, its battery will go flat within five to six hours, making the cell phoneuseless. A fully charged battery becomes necessary especially when your distance fromthe nearest relay station increases. Heres a simple charger that replenishes the cell

phone battery within two to three hours.

Basically, the charger is a current-limited voltage source. Generally, cell phone battery packs require 3.6-6V DC and 180-200mA current for charging. These usually containthree NiCd cells, each having 1.2V rating. Current of 100mA is sufficient for chargingthe cellphone battery at a slow rate. A 12V battery containing eight pen cells givessufficient current (1.8A) to charge the battery connected across the output terminals. The

circuit also monitors the voltage level of the battery. It automatically cuts off thecharging process when its output terminal voltage increases above the predeterminedvoltage level. Timer IC NE555 is used to charge and monitor the voltage level in the

battery. Control voltage pin 5 of IC1 is provided with a reference voltage of 5.6V byzener diode ZD1. Threshold pin 6 is supplied with a voltage set by VR1 and trigger pin2 is supplied with a voltage set by VR2.

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When the discharged cellphone battery is connected to the circuit, the voltage given totrigger pin 2 of IC1 is below 1/3Vcc and hence the flip-flop in the IC is switched on totake output pin 3 high. When the battery is fully charged, the output terminal voltageincreases the voltage at pin 2 of IC1 above the trigger point threshold. This switches off

the flip-flop and the output goes low to terminate the charging process. Threshold pin 6of IC1 is referenced at 2/3Vcc set by VR1. Transistor T1 is used to enhance the chargingcurrent. Value of R3 is critical in providing the required current for charging. With thegiven value of 39-ohm the charging current is around 180 mA.

The circuit can be constructed on a small general purpose PCB. For calibration of cut-off voltage level, use a variable DC power source. Connect the output terminals of thecircuit to the variable power supply set at 7V. Adjust VR1 in the middle position andslowly adjust VR2 until LED1 goes off, indicating low output. LED1 should turn onwhen the voltage of the variable power supply reduces below 5V. Enclose the circuit ina small plastic case and use suitable connector for connecting to the cellphone battery.

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SEMINAR REPORTON

CABLE MODEMS

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CABLE MODEMS

The term Cable Modem is quite new and refers to a modem that operates over theordinary cable TV network cables. Basically you just connect the Cable Modem to theTV outlet for your cable TV, and the cable TV operator connects a Cable Modem

Termination System (CMTS) in his end (the Head-End). Actually the term "CableModem" is a bit misleading, as a Cable Modem works more like a Local Area Network (LAN) interface than as a modem.Cable modems allow consumers access to the Internet at higher speeds and at a fractionof the time it takes traditional telephone modems.This is true for two reasons:1) Broadband networks make the connection up to a hundred times faster 2) The service is "always on," meaning customers get the information they want, whenthey want it.

Unlike telephone modems, cable modems allow consumers to keep their telephone lines

open for voice conversations.

A CATV network is designed and used for cable TV distribution. With an upgrade of the system, it is normally possible to allow signals to flow in both directions. Higher frequencies flow

Toward the subscriber and the lower frequencies go in the other direction. This is done by upgrades to the amplifiers in the cable

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Distribution network etc. Most CATV networks are Hybrid Fiber-Coax (HFC) networks.The signals run in fiber-optical cables from the Head-End center to locations near thesubscriber. At that point the signal is converted to coaxial cables that run to thesubscriber premises. One CMTS will normally drive about 1-2000 simultaneous CableModem users on a single TV channel. If more Cable Modems are required, the numbers

of TV channels are increased by adding more channels to the CMTS.

A number of different Cable Modem configurations are possible. These threeconfigurations are the main products we see

Now. Over time more systems will arrive.

EXTERNAL CABLE MODEM

The external Cable Modem is the small external box that connects to your computer normally through an ordinary Ethernet connection. You will need to add a (cheap)Ethernet card to your computer before you can connect the Cable Modem. A plus is

that you can connect more computers to the Ethernet. Also the Cable Modem workswith most operating systems and hardware platforms, including Mac, UNIX, laptopcomputers etc.Another interface for external Cable Modems is USB, which has theadvantage of installing much faster (something that matters, because the cable operatorsare normally sendingTechnicians out to install each and every Cable Modem). The downside is that you canonly connect one PC to a USB based Cable Modem.

INTERNAL CABLE MODEM

The internal Cable Modem is typically a PCI bus add-in card for a PC. That might be the

cheapest implementation possible, but it has a number of drawbacks. First problem isthat it can only be used in desktop PC's. Mac's and laptops are possible, but require adifferent design. Second problem is that the cable connector is not galvanic isolatedfrom AC mains. This may pose a problem in some CATV networks, requiring a moreexpensive upgrade of the network installations. Some countries and/or CATV networksmay not be able to use internal cable modems at all for technical and/or regulatoryreasons.Interactive Set-Top Box

The interactive set-top box is really a cable modem in disguise. The primary function of the set-top box is to provide more TV channels on the same limited number of

frequencies. This is possible with the use of digital television encoding (DVB). Aninteractive set-top box provides a return channel often through the ordinary plain oldtelephone system (POTS) that allows the user access to web-browsing, email etc.directlyon the TV screen.

TYPICAL MODEM INSTALLAT ION

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When installing a Cable Modem, a power splitter and a new cable are usually required.The splitter divides the signal for the "old" installations and the new segment thatconnects the Cable Modem. No TV-sets are accepted on the new string that goes to theCable Modem. The transmitted signal from the Cable Modem can be so strong; that anyTV sets connected on the same string might be disturbed. The isolation of the splitter

may not be sufficient, so an extra high-pass filter can be needed in the string that goes tothe TV sets. The high-pass filter allows only the TV channel frequencies to pass, and blocks the upstream frequency band. The other reason for the filter is to block ingress inthe low upstream frequency range from the in-house wiring. Noise injected at eachindividual residence accumulates in the upstream path towards the head-end, so it isessential to keep it at a minimum at every single residence that needs Cable Modemservice.

Cable Modems are different, but the basic architecture is more or less the same as shownabove. The major components are outlined below, along with an indication of somecompanies that are know to deliver products to the open market. Many other companies

are working in the field, but may not be so well known to me - or may only producecomponents for their own use

Cable modem technology offers high-speed access to the Internet and World Wide Webservices. Cable data networks integrate the elements necessary to advance beyondmodem technology and provide such measures as privacy, security, data networking,Internet access, and quality-of-service features. The end-to-end network architectureenables a user cable modem to connect to a CMTS which, in turn, connects to a regionaldata center for access to Internet services. Thus, through a system of network connections, a cable data network is capable of connecting users to other users anywherein the global network. Because cable operates at speeds many times faster than a dialup

phone line, it is now possible to view streaming video clips real-time, download multi-megabyte software programs in seconds, videoconference with friends and family and play video games on-line. These capabilities were not practical nor, in some cases, even possible with 56K dialup. In addition, cable Internet subscribers can be fully connected,24 hours a day, to both remote and local services without interfering with their cabletelevisionService or tying up a phone line. The requirements for greater bandwidth and speed is onthe rise. With the many advantages,Cable Modems with the present technology seem to be a feasible solutions.

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BIBLIOGRAPHY

http://hobby_elec.piclist.com/e_resistor.htm

http://hobby_elec.piclist.com/e_capa.htm

http://hobby_elec.piclist.com/e_diode.htm

http://hobby_elec.piclist.com/e_transist.htm

http://hobby_elec.piclist.com/e_ic.htm

http://en.wikipedia.org/wiki/Multimeter

http://en.wikipedia.org/wiki/Oscilloscope

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http://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/mar2004/Cir-01-mobilecharger.pdf&title=Mobile%20Cellphone%20Charger

http://www.101seminartopics.com/cable-modems/
http://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/mar2004/Cir-01-mobilecharger.pdf&title=Mobile%20Cellphone%20Chargerhttp://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/mar2004/Cir-01-mobilecharger.pdf&title=Mobile%20Cellphone%20Chargerhttp://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/mar2004/Cir-01-mobilecharger.pdf&title=Mobile%20Cellphone%20Chargerhttp://www.101seminartopics.com/cable-modems/http://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/mar2004/Cir-01-mobilecharger.pdf&title=Mobile%20Cellphone%20Chargerhttp://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/mar2004/Cir-01-mobilecharger.pdf&title=Mobile%20Cellphone%20Chargerhttp://www.electronicsforu.com/electronicsforu/lab/ad.asp?url=/EFYLinux/circuit/mar2004/Cir-01-mobilecharger.pdf&title=Mobile%20Cellphone%20Chargerhttp://www.101seminartopics.com/cable-modems/

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