electronics is the branch of science and technology which makes use of the controlled motion of...

8/8/2019 Electronics is the Branch of Science and Technology Which Makes Use of the Controlled Motion of Electrons Throug

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Amritsar College of Engineering & Technology, Amritsar

PROJECT

REPORT OF

ONE WEEK

TRAINING IN

CSE

DEPARTMENT

6 WEEKS INSTITUTIONAL TRAININGECE B3


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Introduction to C++C++ is an extended version C. C was developed at Bell Labs. in 1978. The purpose was

to create a simple language (simpler than assembly & machine code...) which can be used

on a variety of platforms. Later in the early 1980's C was extended to C++ to create an

object-oriented language. O(bject) O(riented) P(rogramming) is a style of programming

in which programs are made using Classes. A class id code in a file separate from the

main program - more on classes later. OOP in general & C++ in particular made it

possible to handle the complexity of graphical environments

C++ has been used successfully for every type of programming problem imaginable fromoperating system to spreadsheet to expert system-and efficient compilers are available for machine ranging in power from the Apple Macintosh to the Cray Super Computer.

The largest measure of C++ success seems to be based on purely practical considerations:- The portability of the compiler.- The standard library concept.- Powerful and varied repertoire of operators.- An elegant syntax.- Ready access to the hardware when needed.- And the ease with which applications can be optimized by hand coding isolated

procedures.

C++ is often called a middle level programming language. This is not a reflection on itslack of programming power but more a reflection on its capability to access the system

low level function. Mot high level languages provide every thing the programmer mightwant to do already build into the language. A low level language provides nothing other than access to the machine basic instruction set.



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1.Program to find largest of three nos. and arrange them in ascending

order

#include#includevoid main(){int i,j,temp,large,a[3];cout


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2.Program to enter any three nos. and generate series upto next threenos.#include#include#includevoid main(){clrscr();int a,b,c;int i,n,d,t,r;couta>>b>>c;d=b-a;if(b-a==c-a){for(i=4;i


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#include#include#include#includevoid main(){clrscr();char s1[50],s2[50];cout


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#include#includeclass prime{

public:int num;void prim(){int i,flag=0;

for(i=2;i


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0 11 0 1.n#include

#includevoid main(){clrscr();int i,j,n;coutn;for(i=0;i


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#includeclass bank {

public:int balance;void deposit(){int amt;coutamt;

balance=balance+amt;}void withdraw(){int amt;coutamt; balance=balance-amt;}void display(){cout


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obj.display(); break;case4:x=1;

break;default:cout


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class student{

private:int rn;char name[50];char add[50];

public:void readdata(){coutname;coutadd;}void displaydata(){

cout


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obj.display();getch();}

Output:-Enter name Shreya aggarwalEnter address 53-a rani ka baghEnter marks 98Enter fathers name Anil aggarwal

Name is shreya aggarwalAddress is 53-a rani ka baghMarks is 98Fathers name is anil aggarwal



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PROJECT

REPORT OF

ONE WEEK

TRAINING IN

MECHANICAL

DEPARTMENT



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PROJECT

REPORT OF

FOUR WEEK

TRAINING IN

ECE

DEPARTMENTINTRODUCTION TO ELECTRONICS



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Electronics is the

branch of science and

technology which

makes use of the

controlled motion of

electrons through different media and vacuum. The ability to control electron flow is

usually applied to information handling or device control. Electronics is distinct from

electrical science and technology, which deals with the generation, distribution, control

and application of electrical power. This distinction started around 1906 with the

invention by Lee De Forest of the triode , which made electrical amplification possible

with a non-mechanical device. Until 1950 this field was called "radio technology"

because its principal application was the design and theory of radio transmitters , receivers

and vacuum tubes .

Most electronic devices today use semiconductor components to perform electron

control. The study of semiconductor devices and related technology is considered a

branch of physics , whereas the design and construction of electronic circuits to solve

practical problems come under electronics engineering . This article focuses on

engineering aspects of electronics.

Types of circuits

http://en.wikipedia.org/wiki/Sciencehttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Electronshttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Lee_De_Foresthttp://en.wikipedia.org/wiki/Triodehttp://en.wikipedia.org/wiki/Amplifierhttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Receiver_(radio)http://en.wikipedia.org/wiki/Vacuum_tubehttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Physicshttp://en.wikipedia.org/wiki/Electronic_circuithttp://en.wikipedia.org/wiki/Electronics_engineeringhttp://en.wikipedia.org/wiki/Engineeringhttp://en.wikipedia.org/wiki/Sciencehttp://en.wikipedia.org/wiki/Technologyhttp://en.wikipedia.org/wiki/Electronshttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Lee_De_Foresthttp://en.wikipedia.org/wiki/Triodehttp://en.wikipedia.org/wiki/Amplifierhttp://en.wikipedia.org/wiki/Transmitterhttp://en.wikipedia.org/wiki/Receiver_(radio)http://en.wikipedia.org/wiki/Vacuum_tubehttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Physicshttp://en.wikipedia.org/wiki/Electronic_circuithttp://en.wikipedia.org/wiki/Electronics_engineeringhttp://en.wikipedia.org/wiki/Engineering


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Circuits and components can be divided into two groups: analog and digital. A particular

device may consist of circuitry that has one or the other or a mix of the two types

1. Analog circuits

Most analog electronic appliances, such as radio receivers, are constructed from

combinations of a few types of basic circuits. Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits. Analog circuits are sometimes

called linear circuits although many non-linear effects are used in analog circuits such

as mixers, modulators, etc. Good examples of analog circuits include vacuum tube and

transistor amplifiers, operational amplifiers and oscillators. One rarely finds modern

circuits that are entirely analog. These days analog circuitry may use digital or even

microprocessor techniques to improve performance. This type of circuit is usually called

"mixed signal" rather than analog or digital. 46069025.doc

http://en.wikipedia.org/wiki/Analog_signalhttp://en.wikipedia.org/wiki/Analog_signalhttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Linear_circuithttp://en.wikipedia.org/wiki/Linear_circuithttp://en.wikipedia.org/wiki/File:HitachiJ100A.jpghttp://en.wikipedia.org/wiki/Analog_signalhttp://en.wikipedia.org/wiki/Radiohttp://en.wikipedia.org/wiki/Linear_circuit


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The primary characteristics of a resistor are the resistance, the tolerance , maximum

working voltage and the power rating. Other characteristics include temperature

coefficient, noise , and inductance . Less well-known is critical resistance , the value below

which power dissipation limits the maximum permitted current flow, and above which the

limit is applied voltage. Critical resistance is determined by the design, materials and

dimensions of the resistor.Resistors can be integrated into hybrid and printed circuits , as

well as integrated circuits . Size, and position of leads (or terminals) are relevant to

equipment designers; resistors must be physically large enough not to overheat when

dissipating their power.

(a) Series Resistor Circuit

As the resistors are connected together in series the same current passes through each

resistor in the chain and the total resistance, R T of the circuit must be equal to the sum of

all the individual resistors added together. That is

R T = R 1 + R 2 + R 3

http://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Engineering_tolerance#Electrical_component_tolerancehttp://en.wikipedia.org/wiki/Power_(physics)http://en.wikipedia.org/wiki/Temperature_coefficienthttp://en.wikipedia.org/wiki/Temperature_coefficienthttp://en.wikipedia.org/wiki/Electrical_noisehttp://en.wikipedia.org/wiki/Inductancehttp://en.wikipedia.org/w/index.php?title=Critical_resistance&action=edit&redlink=1http://en.wikipedia.org/wiki/Hybrid_circuithttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Integrated_circuitshttp://en.wikipedia.org/wiki/Integrated_circuitshttp://en.wikipedia.org/wiki/File:Resistors_on_tape.jpghttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Engineering_tolerance#Electrical_component_tolerancehttp://en.wikipedia.org/wiki/Power_(physics)http://en.wikipedia.org/wiki/Temperature_coefficienthttp://en.wikipedia.org/wiki/Temperature_coefficienthttp://en.wikipedia.org/wiki/Electrical_noisehttp://en.wikipedia.org/wiki/Inductancehttp://en.wikipedia.org/w/index.php?title=Critical_resistance&action=edit&redlink=1http://en.wikipedia.org/wiki/Hybrid_circuithttp://en.wikipedia.org/wiki/Printed_circuit_boardhttp://en.wikipedia.org/wiki/Integrated_circuits


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and by taking the individual values of the resistors in our simple example above, the total

resistance is given as:

R T = R 1 + R 2 + R 3 = 1k + 2k + 6k = 9k

Therefore, we can replace all 3 resistors above with just one single resistor with a value

of 9k. Where 4, 5 or even more resistors are all connected together in series, the total

resistance of the series circuit R T would still be the sum of all the individual resistors

connected together. This total resistance is generally known as the Equivalent

Resistance and can be defined as ; " a single value of resistance that can replace any

number of resistors without altering the values of the current or the voltage in the

circuit" . Then the equation given for calculating total resistance of the circuit when

resistors are connected together in series is given as:

Series Resistor Equation

R total = R 1 + R 2 + R 3 + ..... R n etc.

(b) Resistors in Parallel

Resistors are said to be connected together in " Parallel " when both of their terminals are

respectively connected to each terminal of the other resistor or resistors. The voltage drop

across all of the resistors in parallel is the same. Then, Resistors in Parallel have a

Common Voltage across them and in our example below the voltage across the resistors

is given as:

VR1 = V R2 = V R3 = V AB = 12V

In the following circuit the resistors R 1, R 2 and R 3 are all connected together in parallel

between the two points A and B.



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Parallel Resistor Circuit

In the previous series resistor circuit we saw that the total resistance, R T of the circuit was

equal to the sum of all the individual resistors added together. For resistors in parallel theequivalent circuit resistance R T is calculated differently.

Parallel Resistor Equation

Resistor Combinations

Resistor circuits that combine series and parallel resistors circuits together are generally

known as Resistor Combination circuits and the method of calculating their combined

resistance is the same as that for any individual series or parallel circuit. For example:

For example, Calculate the total current (I) taken from the 12v supply.



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At first glance this may seem a difficult task, but if we look a little closer we can see that

the two resistors, R 2 and R 3 are both connected together in a "SERIES" combination so

we can add them together and the resultant resistance for this would be,

R 2 + R 3 = 8 + 4 = 12

So now we can replace both the resistors R 2 and

R 3 with a single resistor of resistance value 12



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Now we have single resistor R T in "PARALLEL" with the resistor R 4, (resistors in parallel) and again we can reduce this combination to a single resistor value of R (combination)

using the formula for two parallel connected resistors as follows.

The resultant circuit now looks something like this:



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The two remaining resistances, R 1 and R (comb) are connected together in a "SERIES"

combination and again they can be added together so the total circuit resistance between

points A and B is therefore given as:

R ( A - B ) = R comb + R 1 = 6 + 6 = 12 . and a single resistance of just 12 can be used

to replace the original 4 resistor combinations circuit above.

Resistor Colour Code

The resistance value, tolerance, and watt rating of the resistor are generally printed onto

the body of the resistor as numbers or letters when the resistor is big enough to read the

print, such as large power resistors. When resistors are small such as 1/4W Carbon andFilm types, these specifications must be shown in some other manner as the print would

be too small to read. So to overcome this, small resistors use coloured painted bands to

indicate both their resistive value and their tolerance with the physical size of the resistor

indicating its wattage rating. These coloured painted bands are generally known as a

Resistors Colour Code .An International resistor colour code scheme was developed

many years ago as a simple and quick way of identifying a resistors value. It consists of

coloured rings (in spectral order) whose meanings are illustrated :



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Units

The ohm (symbol: ) is the SI unit of electrical resistance , named after Georg Simon

Ohm . Commonly used multiples and submultiples in electrical and electronic usage are

the milliohm (1x10 3), kilohm (1x10 3), and megohm (1x10 6).

Ohm's law

The behavior of an ideal resistor is dictated by the relationship specified in Ohm's law :

V = IR

Ohm's law states that the voltage (V) across a resistor is proportional to the current (I)

through it where the constant of proportionality is the resistance (R).

CAPACITORS

http://en.wikipedia.org/wiki/Ohm_(unit)http://en.wikipedia.org/wiki/%CE%A9http://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Georg_Simon_Ohmhttp://en.wikipedia.org/wiki/Georg_Simon_Ohmhttp://en.wikipedia.org/wiki/Ohm's_lawhttp://en.wikipedia.org/wiki/Ohm_(unit)http://en.wikipedia.org/wiki/%CE%A9http://en.wikipedia.org/wiki/SIhttp://en.wikipedia.org/wiki/Electrical_resistancehttp://en.wikipedia.org/wiki/Georg_Simon_Ohmhttp://en.wikipedia.org/wiki/Georg_Simon_Ohmhttp://en.wikipedia.org/wiki/Ohm's_law


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Just like the Resistor , the Capacitor or sometimes referred to as a Condenser is a

passive device, and one which stores energy in the form of an electrostatic field which

produces a potential ( Static Voltage ) across its plates. In its basic form a capacitor

consists of two parallel conductive plates that are not connected but are electricallyseparated either by air or by an insulating material called the Dielectric . When a voltage

is applied to these plates, a current flows charging up the plates with electrons giving one

plate a positive charge and the other plate an equal and opposite negative charge. This

flow of electrons to the plates is known as the Charging Current and continues to flow

until the voltage across the plates (and hence the capacitor) is equal to the applied voltage

Vc.

Types of Capacitors

Ceramic Capacitor

Ceramic Capacitors or Disc Capacitors as they are generally called, are made by coating

two sides of a small porcelain or ceramic disc with silver and are then stacked

together to make a capacitor. For very low capacitance values a single ceramic disc

of about 3-6mm is used. Ceramic capacitors have a high dielectric constant (High-

K) and are available so that relatively high capacitances can be obtained in a small

physical size. They exhibit large non-linear changes in capacitance against

temperature and as a result are used as de-coupling or by-pass capacitors as they

are also non-polarized devices. Ceramic capacitors have values ranging from a few

picofarads to one or two microfarads but their voltage ratings are generally quite

low.

Ceramic types of capacitors generally have a 3-digit code printed onto their body toidentify their capacitance value. For example, 103 would indicate 10 x 103pF which is

equivalent to 10,000 pF or 0.01F. Likewise, 104 would indicate 10 x 104pF which is

equivalent to 100,000 pF or 0.1F and so on. Letter codes are sometimes used to indicate

their tolerance value such as: J = 5%, K = 10% or M = 20% etc.

http://www.electronics-tutorials.ws/resistor/res_1.htmlhttp://www.electronics-tutorials.ws/resistor/res_1.html


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CERAMIC CAPACITOR

Electrolytic capacitor

An electrolytic capacitor is a type of capacitor that uses an electrolyte , an ionic

conducting liquid, as one of its plates, to achieve a larger capacitance per unit volumethan other types. They are often referred to in electronics usage simply as "electrolytics".

They are used in relatively high-current and low-frequency electrical circuits , particularly

in power supply filters, where they store charge needed to moderate output voltage and

current fluctuations in rectifier output. They are also widely used as coupling capacitors

in circuits where AC should be conducted but DC should not. There are two types of

electrolytics; aluminum and tantalum .

Electrolytic capacitors are capable of providing the highest capacitance values of anytype of capacitor. However they have drawbacks which limit their use. The voltage

applied to them must be polarized; one specified terminal must always have positive

potential with respect to the other. Therefore they cannot be used with AC signals

without a DC bias. They also have very low breakdown voltage, higher leakage current

and inductance, poorer tolerances and temperature range, and shorter lifetimes compared

to other types of capacitors

http://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/Power_supplyhttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Tantalum_capacitorhttp://www.google.co.in/imgres?imgurl=http://www.leds-capacitors-manufacturer.com/rimages/547/Ceramic-Capacitors.jpg&imgrefurl=http://www.leds-capacitors-manufacturer.com/Ceramic-Capacitors.htm&usg=__5HH0QFEytu2ECANL0UwawVNCWJw=&h=523&w=478&sz=39&hl=en&start=2&tbnid=HLkoHVLFGPx_nM:&tbnh=131&tbnw=120&prev=/images%3Fq%3Dceramics%2Bcapacitors%26hl%3Den%26gbv%3D2%26tbs%3Disch:1&itbs=1http://en.wikipedia.org/wiki/Capacitorhttp://en.wikipedia.org/wiki/Electrolytehttp://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/Power_supplyhttp://en.wikipedia.org/wiki/Rectifierhttp://en.wikipedia.org/wiki/Alternating_currenthttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Tantalum_capacitor


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ELECTROLYTIC CAPACITOR

(a) Capacitors in Series

Capacitors are said to be "connected in series" when they are effectively "daisy chained"

together in a single line. The charging current (Ic) flowing through the capacitors is THE

SAME for the same amount of time so each capacitor stores the same amount of charge

regardless of its capacitance and:

QT = Q 1 = Q 2 = Q 3 etc.....

In the following circuit, capacitors, C 1, C 2 and C 3 are connected together in series

between points A and B.

Figure 4 : Series Capacitor Circuit

(b)Capacitors in Parallel

Capacitors are said to be connected "in parallel" when both of their terminals are

respectively connected to each terminal of the other capacitor or capacitors. The



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voltage (Vc) across all the capacitors connected in parallel is THE SAME. Then,

parallel capacitors have a Common Voltage supply across them and:

VC1 = V C2 = V C3 = V AB = 12V

In the following circuit capacitor, C 1 and capacitor, C 2 are connected in parallel between

points A and B.

When capacitors are connected in parallel the total capacitance in the circuit is equal to

the sum of all the individual capacitors added together. That is:

Parallel Capacitors Equation

Where all the capacitors are given in the same capacitance units, either uF, nF or pF.

Inductor

An inductor or a reactor is a passive electrical component that can store energy in a

magnetic field created by the electric current passing through it. An inductor's ability to

http://en.wikipedia.org/wiki/Passive_componenthttp://en.wikipedia.org/wiki/Electronic_componenthttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Passive_componenthttp://en.wikipedia.org/wiki/Electronic_componenthttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Electric_current


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store magnetic energy is measured by its inductance ,

in units of henries . Typically an inductor is a

conducting wire shaped as a coil, the loops helping

to create a strong magnetic field inside the coil dueto Ampere's Law. Due to the time-varying magnetic

field inside the coil, a voltage is induced, according

to Faraday's law of electromagnetic induction ,

which by Lenz's Law opposes the change in current

that created it. Inductors are one of the basic

electronic components used in electronics where

current and voltage change with time, due to the

ability of inductors to delay and reshape alternating

currents. In everyday speak inductors are sometimes

called chokes, but this refers to only a particular type and purpose of inducto r

2.ACTIVE COMPONENTS

Active components are those that have gain or directionality, in contrast to passive

components, which have neither. They include semiconductor devices and vacuum tubes

(valves).

DIODES

http://en.wikipedia.org/wiki/Inductancehttp://en.wikipedia.org/wiki/Henry_(unit)http://en.wikipedia.org/wiki/Ampere's_Lawhttp://en.wikipedia.org/wiki/Faraday's_law_of_inductionhttp://en.wikipedia.org/wiki/Lenz's_Lawhttp://en.wikipedia.org/wiki/Inductancehttp://en.wikipedia.org/wiki/Henry_(unit)http://en.wikipedia.org/wiki/Ampere's_Lawhttp://en.wikipedia.org/wiki/Faraday's_law_of_inductionhttp://en.wikipedia.org/wiki/Lenz's_Law


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1.The Zener Diode

In the previous Signal Diode tutorial we saw that a "reverse biased" diode passes very

little current but will suffer breakdown or damage if the reverse voltage applied across itis made to high. However, Zener Diodes or "Breakdown Diodes" as they are sometimes

called, are basically the same as the standard junction diode but are specially made to

have a low pre-determined Reverse Breakdown Voltage , called the "Zener Voltage"

(Vz). In the forward direction it behaves just like a normal signal diode passing current,

but when the reverse voltage applied to it exceeds the selected reverse breakdown voltage

a process called Avalanche Breakdown occurs in the depletion layer and the current

through the diode increases to the maximum circuit value, which is usually limited by a

series resistor. The point at which current flows can be very accurately controlled (to less

than 1% tolerance) in the doping stage of the diodes construction giving it a specific

Zener Breakdown voltage (Vz) ranging from a few volts up to a few hundred volts.

Zener Diode I-V Characteristics

Zener Diodes are used in the "REVERSE" bias mode, i.e. the anode connects to the

negative supply, and from its I-V characteristics curve above, we can see that the Zener

diode has a region in its reverse bias characteristics of almost a constant voltage

regardless of the current flowing through the diode. This voltage across the diode (it's

Zener Voltage, Vz) remains nearly constant even with large changes in current through

the diode caused by variations in the supply voltage or load. This ability to control itself

can be used to great effect to regulate or stabilise a voltage source against supply or load

variations. The diode will continue to regulate until the diode current falls below the

minimum Iz value in the reverse breakdown region .

http://www.electronics-tutorials.ws/diode/diode_4.htmlhttp://www.electronics-tutorials.ws/diode/diode_4.html


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2.Light Emitting Diodes

Light Emitting Diodes or LEDs , are among the most widely used of all the types of

diodes available. They are the most visible type of diode, that emits a fairly narrow

bandwidth of either visible coloured light, invisible infra-red or laser type light when a

forward current is passed through them. A " Light Emitting Diode " or LED as it is more

commonly called, is basically just a specialised type of PN-junction diode, made from a

very thin layer of fairly heavily doped semiconductor material. When the diode is

Forward Biased, electrons from the semiconductors conduction band combine with holes

from the valence band, releasing sufficient energy to produce photons of light. Because

of this thin layer a reasonable number of these photons can leave the junction and radiate

away producing a coloured light output.

Unlike normal diodes which are

made for detection or power

rectification, and which are

generally made from either

Typical LED CharacteristicsSemiconductor

MaterialWavelengthColour

VF @

20mAGaAs 850-940nm Infra- 1.2v



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Germanium or Silicon

semiconductor material, Light

Emitting Diodes are made from

compound type semiconductor materials such as Gallium

Arsenide (GaAs), Gallium

Phosphide (GaP), Gallium

Arsenide Phosphide (GaAsP),

Silicon Carbide (SiC) or Gallium

Indium Nitride (GaInN). The exact

choice of the semiconductor

material used will determine the

overall wavelength of the photon

light emissions and therefore the

resulting colour of the light

emitted, as in the case of the

visible light coloured LEDs,

(RED, AMBER, GREEN etc)

RedGaAsP 630-660nm Red 1.8vGaAsP 605-620nm Amber2.0vGaAsP:N 585-595nm Yellow2.2vGaP 550-570nm Green 3.5vSiC 430-505nm Blue 3.6vGaInN 450nm White 4.0v

3.The PN-junction

As the N-type material has lost electrons and the P-type has lost holes, the N-type

material has become positive with respect to the P-type. The external voltage required to

overcome this barrier potential that now exists and allow electrons to move freely across

the junction is very much dependent upon the type of semiconductor material used and its

actual temperature, and for Silicon this is about 0.6 - 0.7 volts and for Germanium it is



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about 0.3 - 0.35 volts. This potential barrier will always exist even if the device is not

connected to any external power source.

The significance of this built-in potential is that it opposes both the flow of holes and

electrons across the junction and is why it is called the potential barrier. In practice, a

PN-junction is formed within a single crystal of material rather than just simply joining

or fusing together two separate pieces. Electrical contacts are also fused onto either side

of the crystal to enable an electrical connection to be made to an external circuit.

The Basic Diode Symbol and Static I-V Characteristics.



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But before we can use the PN-junction as a practical device or as a rectifying device we

need to firstly " Bias " the junction, ie connect a voltage potential across it. On the voltage

axis above "Reverse Bias" refers to an external voltage potential which increases the

potential barrier. An external voltage which decreases the potential barrier is said to act in

the "Forward Bias" direction.

There are 3 possible "biasing" conditions for the standard Junction Diode and these are:

1. Zero Bias - No external voltage potential is applied to the PN-junction.

2. Reverse Bias - The voltage potential is connected negative, (-ve) to the P-type

material and positive, (+ve) to the N-type material across the diode which has the

effect of Increasing the

PN-junction width.

3. Forward Bias - The voltage potential is connected positive, (+ve) to the P-type

material and negative, (-ve) to the N-type material across the diode which has the

effect of Decreasing the PN-junction width.



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Reverse Bias.

When a diode is connected in a Reverse Bias condition, a positive voltage is applied to

the N-type material and a negative voltage is applied to the P-type material. The positivevoltage applied to the N-type material attracts electrons towards the positive electrode

and away from the junction, while the holes in the P-type end are also attracted away

from the junction towards the negative electrode. The net result is that the depletion layer

grows wider due to a lack of electrons and holes and presents a high impedance path,

almost an insulator. The result is that a high potential barrier is created thus preventing

current from flowing through the semiconductor material.

A Reverse Biased Junction showing the Increase in the Depletion Layer.

This condition represents the high resistance direction of a PN-junction and practically

zero current flows through the diode with an increase in bias voltage. However, a very

small leakage current does flow through the junction which can be measured in

microamperes, (A). One final point, if the reverse bias voltage Vr applied to the junction

is increased to a sufficiently high enough value, it will cause the PN-junction to overheat

and fail due to the avalanche effect around the junction. This may cause the diode to



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become shorted and will result in maximum circuit current to flow, Ohm's Law and this

shown in the reverse characteristics curve below.

Reverse Characteristics Curve for a Diode.

Sometimes this avalanche effect has practical applications in voltage stabilising circuits

where a series limiting resistor is used with the diode to limit this reverse breakdown

current to a preset maximum value thereby producing a fixed voltage output across the

diode. These types of diodes are commonly known as Zener Diodes and are discussed in

a later tutorial.

2.Forward Bias.

When a diode is connected in a Forward Bias condition, a negative voltage is applied to

the N-type material and a positive voltage is applied to the P-type material. If this

external voltage becomes greater than the value of the potential barrier, 0.7 volts for Silicon and 0.3 volts for Germanium, the potential barriers opposition will be overcome

and current will start to flow as the negative voltage pushes or repels electrons towards

the junction giving them the energy to cross over and combine with the holes being

pushed in the opposite direction towards the junction by the positive voltage. This results

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in a characteristics curve of zero current flowing up to this "knee" voltage and high

current flow through the diode with little increase in the external voltage as shown below.

Forward Characteristics Curve for a Diode.

This results in the depletion layer becoming very thin and narrow and which now

represents a low impedance path thereby producing a very small potential barrier and

allowing high currents to flow. The point at which this takes place is represented on the

static I-V characteristics curve above as the "knee" point.



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Forward Biased Junction Diode showing a Reduction in the Depletion

Layer.

This condition represents the low resistance direction in a PN-junction allowing very

large currents to flow through the diode with only a small increase in bias voltage. The

actual potential difference across the junction or diode is kept constant by the action of

the depletion layer at about 0.3v for Germanium and about 0.7v for Silicon diodes. Since

the diode can conduct "infinite" current above this knee point as it effectively becomes a

short circuit, resistors are used in series with the device to limit its current flow.Exceeding its maximum forward current specification causes the device to dissipate more

power in the form of heat than it was designed for resulting in failure of the device.



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4.Transistor

Bipolar Transistor Construction

The construction and circuit symbols for both the NPN and PNP bipolar transistor are

shown above with the arrow in the circuit symbol always showing the direction of

conventional current flow between the base terminal and its emitter terminal, with the

direction of the arrow pointing from the positive P-type region to the negative N-type

region, exactly the same as for the standard diode symbol.

There are basically three possible ways to connect a Bipolar Transistor within an

electronic circuit with each method of connection responding differently to its input

signal as the static characteristics of the transistor vary with each circuit arrangement.

1. Common Base Configuration - has Voltage Gain but no Current Gain.

2. Common Emitter Configuration - has both Current and Voltage Gain.

3. Common Collector Configuration - has Current Gain but no Voltage

Gain.



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The NPN Transistor

In the previous tutorial we saw that the standard Bipolar Transistor or BJT, comes in

two basic forms. An NPN (Negative-Positive-Negative) type and a PNP (Positive- Negative-Positive) type, with the most commonly used transistor type being the NPN

Transistor . We also learnt that the transistor junctions can be biased in one of three

different ways - Common Base , Common Emitter and Common Collector . In this

tutorial we will look more closely at the "Common Emitter" configuration using NPN

Transistors and an example of its current flow characteristics is given below.

An NPN Transistor Configuration



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Output Characteristics Curves for a Typical Bipolar Transistor

The most important factor to notice is the effect of Vce upon the collector current Ic

when Vce is greater than about 1.0 volts. You can see that Ic is largely unaffected by

changes in Vce above this value and instead it is almost entirely controlled by the base

current, Ib. When this happens we can say then that the output circuit represents that of a

"Constant Current Source". It can also be seen from the common emitter circuit above



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that the emitter current Ie is the sum of the collector current, Ic and the base current, Ib,

added together so we can also say that " Ie = Ic + Ib " for the common emitter

configuration.

The PNP Transistor

The PNP Transistor is the exact opposite to the NPN Transistor device we looked at in

the previous tutorial. Basically, in this type of transistor construction the two diodes are

reversed with respect to the NPN type, with the arrow, which also defines the Emitter

terminal this time pointing inwards in the transistor symbol. Also, all the polarities are

reversed which means that PNP Transistors "sink" current as opposed to the NPN

transistor which "sources" current. Then, PNP Transistors use a small output base current

and a negative base voltage to control a much larger emitter-collector current. The

construction of a PNP transistor consists of two P-type semiconductor materials either side of the N-type material as shown below.

A PNP Transistor Configuration



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Printed circuit board

A printed circuit board , or PCB , is used to mechanically support and

electrically connect electronic components using conductive pathways,

tracks or signal traces etched from copper sheets laminated onto a non-

conductive substrate . It is also referred to as printed wiring board (PWB )

or etched wiring board . A PCB populated with electronic components is a

printed circuit assembly (PCA ), also known as a printed circuit board

assembly (PCBA ).

PCBs are inexpensive, and can be highly reliable. They require much more

layout effort and higher initial cost than either wire-wrapped or point-to-

point constructed circuits, but are much cheaper and faster for high-volume

production. Much of the electronics industry's PCB design, assembly, and

quality control needs are set by standards that are published by the IPC

organization

Integrated circuit

In electronics , an integrated circuit (also known as IC , microcircuit , microchip , silicon

chip , or chip ) is a miniaturized electronic circuit (consisting mainly of semiconductor

devices , as well as passive components ) that has been manufactured in the surface of a

thin substrate of semiconductor material. Integrated circuits are used in almost all

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electronic equipment in use today and have revolutionized the world of electronics.

Computers , cellular phones, and other digital appliances are now inextricable parts of the

structure of modern societies, made possible by the low cost of production of integrated

circuits.

A hybrid integrated circuit is a miniaturized electronic circuit constructed of individual

semiconductor devices, as well as passive components, bonded to a substrate or circuit

board. A monolithic integrated circuit is made of devices manufactured by diffusion of

trace elements into a single piece of semiconductor substrate, a chip.

Multimeter

A multimeter or a multitester, also known as a volt/ohm meter or VOM , is an electronic

measuring instrument that combines several measurement functions in one unit. A typical

multimeter may include features such as the ability to measure voltage, current and

resistance. Multimeters may use analog or digital circuits analog multimeters anddigital multimeters (often abbreviated DMM or DVOM .) Analog instruments are

usually based on a microammeter whose pointer moves over a scale calibrated for all the

different measurements that can be made; digital instruments usually display digits, but

may display a bar of length proportional to the quantity measured.

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A multimeter can be a hand-held device useful for basic fault finding and field service

work or a bench instrument which can measure to a very high degree of accuracy. They

can be used to troubleshoot electrical problems in a wide array of industrial and

household devices such as electronic equipment , motor controls, domestic

appliances , power supplies , and wiring systems.

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MULTY-MELODY GENERATOR WITH

INSTRUMENTAL EFFECTS

DISCRIPTION

The Multi Melody Generator circuit is powered by a 3V battery. A switch (S2) is themain input-select switch for producing different tones in the loudspeaker. Various modesof operation can be selected through DIP switches S3, S4 and S5 connected to pins 3, 5and 7 of UM3481A (IC1), respectively. Pin 7 is the envelope circuit terminal throughwhich instrumental effects are produced. The preamplifier outputs are available at pins 10and 11, which are fed to loudspeaker, driver transistors T1 (SK100) and T2 (SL100),respectively.

When the circuit is switched on by closing switch S1, LED1 glows. When DIP switchesS3 and S5 are closed and S4 is open; and switch S2 is pressed, a melody is generatedthrough the loudspeaker. (The potentiometer VR1 is provided for volume control in thecircuit). Pressing the switch S2 again generates a new melodious tone. If switches S3 andS4 are opened while S5 is closed, the same tone keeps repeating for every press of switchS2. When switch S5 is open, an instrumental effect is generated from the loudspeaker.This effect is produced by the enveloping circuit consisting of capacitor C1 and resistor R2 connected to pin 7 of IC1. Only C1 or R2 or its parallel combination can be used togenerate a distinct instrument effect. To select any of these options, two jumper terminalsJ1 and J2 are provided in the circuit at C1 and R2, respectively. For example, if you wantto use only C1, you can join J1 terminals using hookup wire or jumper cap and keep J2

open. The repetition of the musical effect depends on the status of switches S3 and S4.The oscillation frequency is produced by the resistor and capacitor connected at pins 14and 13 of IC1. This frequency is used as a time base for the tone, rhythm and tempogenerators. The quality of the melody tones depends on this frequency. Resistor R6 (100-kilo-ohm) connected to pin 15 makes the circuit insensitive to variations in the power supply.

electronics is the branch of science and technology which makes use of the controlled motion of...

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