LASER SECURITY ALARM

SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS

FOR THE AWARD OF THE DEGREE

OF

BACHELOR OF TECHNOLOGY IN

ELECTRICAL & ELECTRONICS ENGINEERING

Submitted by:

HEMANT KANT (1210921008)

MEETANSHU SHARMA (1210921017)

YASH KUMAR SINGH (1210921039)

Under the supervision of

MR. MOHAN SHARMA

(Asst. professor)

DEPARTMENT OF ELECTRICAL & ELECTRONICS

ENGINEERING

ALIGARH COLLEGE OF ENGINEERING & TECHNOLOGY, ALIGARH

(Dr. A.P.J. ABDUL KALAM TECHNICAL UNIVERSITY, LUCKNOW)

UTTAR PRADESH

2015-16

i

DECLARATION

We hereby declare that this submission is our own work and that, to the best of our

knowledge and belief it contains no material previously published or written by another

person nor material which to a substantial extent has been accepted for the award of any other

degree of the university or other institute of higher learning, except where due

acknowledgement has been in the text.

Signature of student

Name- HEMANT KANT

Roll No. -1210921008

Signature of student

Name- MEETANSHU SHARMA

Roll No. -1210921017

Signature of student

Name- YASH KUMAR SINGH

Roll No. -1210921039

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DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

ALIGARH COLLEGE OF ENGINEERING & TECHNOLOGY, ALIGARH

(Dr. A.P.J. ABDUL KALAM TECHNICAL UNIVERSITY, LUCKNOW)

CERTIFICATE

This is to certify that project of the requirement for the award of degree B.Tech in department

of ELECTRICAL & ELECTRONICS ENGINEERING of A.K.T.U. is the record of the

candidate own work carried out by him under my/our supervision. The matter embodied in

this thesis is original and has not been submitted for the award of any other degree.

Under Supervision: HOD:

MOHAN SHARMA ARIF HASAN (Assistant professor) (Assistant professor)

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ACKNOWLEDGEMENT

We have taken efforts in this project. However, it would not have been possible without the

kind support and help of many individuals and department. We would like to extend our

sincere thanks to all of them.

We wish to express our sincere gratitude to Miss. Swati Yadav (Asst. Professor, EN Dept.)

for providing us all help to complete this project.

We sincerely thank Mr. Mohan Sharma (Asst. Professor, EC Dept.) for their guidance and

encouragement in carrying out this project work. We also wish to express our gratitude to all

effort of his to make this project easy by support.

We also thank Mr. Arif Hassan (Head of Electrical and Electronics Engineering

Department) for providing us the opportunity to embark on this project.

HEMANT KANT (1210921008)

MEETANSHU SHARMA (1210921017)

YASH KUMAR SINGH (1210921039)

iv

ABSTRACT

LASER-Ray goes through long distance without scattering effect and the Ray is almost

invisible. Only the radiation point and incident point is visible. So by this security project we

can make an invisible boundary of a sensitive area. There is two part of the system. One is

transmitter and other is receiver.

The transmitter part is built with a LASER radiator, a pair of dry cell batteries, an on -off

switch and a stand to hold it. The receiver side, there is a focusing LDR (Light depending

Resistor) sensor to sense the LASER continuously. The LDR sensor also holds with a stand

and it connected with the main driver circuit. The circuit has two parts. One is filtered the

signal of discontinuity ray and others is alarm circuit. When anybody crossover the invisible

ray the main circuit sense the discontinuity by sensor and turn on the alarm circuit. If once the

alarm circuit is on it will still ringing until push the reset button.

There is two option of ringing. One is the duration of ringing depends on preset timer and

another reset manually. Any option can be set by switch. If anybody wants to bind a sensitive

area with the single and break by object it ringing. The system has built with low cost and

high performance. The power consumption of the system is very low. Introduction

The realization of this project will involve the construction of a light sensitive alarm. In this

project are to distinguish two parts. The first will consist of a written work. This paper will

explain the operation of the alarms, as well as the different types of alarms in the world. In

addition to explaining the different components of the alarm, that is made for this project.

The second part of the project will consist in the physical installation of the alarm and its

presentation. Alarms are becoming more widespread due to the need for greater security.

Until a few years ago, security systems were installed in specific locations, to preserve for

burglary, robbery or fire. Today it is used in homes, small businesses, factories, and high-risk

locations, such as banks and jewelers.

A security system must not provide false alarms, since in practice it is as ineffective as one

that can easily be violated. Prone to false alarm, besides not being insurance system tends to

be ignored. Legislation in this field requires certain establishments such as banks, savings and

credit institutions in general gun shops and jewelers to have in their facilities, systems, and

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these systems should be installed by approved companies for added security. A good security

system, to be successful, you must be connected via a telephone transmitter to a central

station with 24 hour security. This is the only way to provide continuous security to the

factory, warehouse, office or family housing in question. Before installation it should take

into account certain considerations very clear since they will define the installation to be

carried out. It should be noted that it is virtually impossible to make a proper fit, given

existing in each own constraints and limitations of the equipment, because even come to a

very high degree of reliability are always risks.

Which do not require interfacing with the security company because they have warning

system and outdoor signage, and these are fairly simple constitution? However, the trend in

Europe is to connect these small systems security certified security company, since it

guarantees all the senses.

vi

TABLE OF CONTENTS

DECLARATION i

CERTIFICATE ii

ACKNOWLEDGEMENT iii

ABSTRACT iv

TABLE OF CONTENTS vi

LIST OF FIGURES ix

CHAPTER: 1 1

1. INTRODUCTION 2

1.1 AIM 2

1.2 FEATURES OF SYSTEM 2

1.3 SYSTEM COMPONENTS 2

CHAPTER: 2 4

2. LASER 4

2.1 WORKING PRINCLE OF LASER 5

CHAPTER: 3 7

3. LIGHT DEPENDENT RESISTER 7

3.1 WORKING PRINCIPLE OF LDR 7

3.2 CHARACTERISTIC OF LDR 8

CHAPTER:4 9

4. LIGHT EMITTING DIODE 9

4.1 WORKING OF LED 9

CHAPTER: 5 11

5. BASIC COMPONENTS OF SYSTEM 11

vii

5.1 PROTO BOARD AND CONNECTION BOARD 11

5.2 RESISTOR 12

5.3 VARIABLE RESISTOR 12

5.4 PRECISION RESISTOR 13

5.5 COLOR CODE 14

5.6 CAPACITOR 15

5.7 TYPES OF CAPACITOR 16

5.7.1 CERAMIC CAPACITOR 16

5.7.2 FILM CAPACITOR 17

5.7.3 FILM POWER CAPACITOR 17

5.7.4 ELECTROLYTE CAPACITOR 17

CHAPTER: 6 19

6. ALARM AND BUZZER 19

6.1 VOLTAGE 19

6.2 ELECTRIC CURRENT 19

6.3 OHM'S LAW 19

CHAPTER: 7 21

7. VOLTAGE REGULATOR 21

7.1 7805 VOLTAGE REGULATOR IC 21

7.2 PIN CONFIGURATION 22

7.3 WORKING OF 7805 IC 22

CHAPTER: 8 24

8. TIMER IC 555 24

8.1 PIN CONFIGURATION 24

8.2 WORKING AND CIRCUIT DIAGRAM 26

CHAPTER: 9 28

9. SEVEN SEGMENT DISPLAY 28

viii

9.1 BASIC COMPONENT 28

CHAPTER: 10 30

10. TRANSISTOR 30

10.1 TYPES OF TRANSISTOR 31

10.1.1 BIPOLAR JUNCTION TRANSISTOR 31

10.1.2 FIELD EFFECT TRANSISTOR 31

10.2 BC-548 TRANSISTOR 32

CHAPTER: 11 33

11. ANALOG COUNTER 33

11.1 PIN CONFIGURATION AND FUNCTIONAL DIAGRAM 33

11.2 INTERACTING 34

11.2.1 INTERFACING WITH 7 SEGMENT DISPLAY 34

11.2.2 INTERFACING WITH IC 555 35

CHAPTER: 12 36

12. CIRCUIT DIAGRAM AND WORKING OF SYSTEM 36

12.1 LASER SYSTEM CIRCUIT 36

12.2 WORKING OF CIRCUIT 36

12.3 COUNTER SYSTEM CIRCUIT 37

12.4 WORKING LASER COUNTER 38

CHAPTER: 13 39

13.METHODOLOGY AND SCOPE 39

REFERENCES 41

ix

LIST OF FIGURES

1. Fig 2.1 5 VOLT LASER 4

2. Fig 2.2 STIMULATED EMISSION VIEW 5

3. Fig 3.1 LDR 7

4. Fig 3.2 CHARACTERISTIC OF LDR 8

5. Fig 4.1 ELECTRONIC SYMBOL OF LED 9

6. Fig 4.2 INNER WORKING OF LED 9

7. Fig 4.3 LEDs 10

8. Fig 5.1 CONNECTION BOARD OR PROTO BOARD 11

9. Fig 5.2 ELECTRONIC SYMBOL OF RESISTOR 12

10. Fig 5.3 VARIABLE RESISTOR 13

11. Fig 5.4 RESISTOR 14

12. Fig 5.5 COLOR CODES FOR RESISTANCES 15

13. Fig 5.6 CAPACITOR 15

14. Fig 5.7 CATEGORIES OF CAPACITORS 16

15. Fig 5.8 ELECTROLYTE CAPACITOR 18

16. Fig 6.1 VOLT BUZZERS 20

17. Fig 7.1 VOLTAGE REGULATOR 21

18. Fig7.2 PIN DIAGRAM OF VOLTAGE REGULATOR 22

19. Fig 7.3 7805 VR CIRCUIT DIAGRAM 23

20. Fig 8.1 PIN DIAGRAM OF IC 555 24

21. Fig 8.2 CIRCUIT DIAGRAM OF IC 555 26

22. Fig 9.1 SSD 28

23. Fig 9.2 SEGMENT OF DISPLAY 29

24. Fig 10.1 TYPICAL TRANSISTOR VIEW 30

25. Fig 10.2 MOSFET 31

26. Fig 10.3 BC-548 TRANSISTOR 32

x

27. Fig 11.1 PIN DIAGRAM OF COUNTER IC 33

28. Fig 11.2 INTERFACE OF SSD & IC-4033 34

29. Fig 12.1 LASER SYSTEM CIRCUIT 36

30. Fig 12.2 CIRCUIT DIAGRAM OF COUNTER SYSTEM 37

1

CHAPTER-1

INTRODUCTION

Security is a most important factor today. Technology develops day by day in the world. The

crime gang also improves their technology to perform their operation. So technology of

security should be modern with time to protect the crime works. We decide to make a

security project as our project.

In this project we have used laser light to cover a large area. We know laser light goes

through long distance without scattering effect. It’s also visible only at source and incident

point, otherwise invisible. These two properties help us to build up a modern security system,

which may name as “laser security”.

When any person or object crossover the laser line the security alarm will ringing and also

the focus light will “on” to focus the entrance of unauthorized person. We can make a

security boundary of single laser light by using mirror at every corner for reflection.

Siren is a device that produces loud noise. They are the means communication. Sirens can be

seen in emergency vehicles such as police cars, ambulances and fire engines. Generally,

sirens are used as indication or warning. There are different circuits to produce different

sirens. Here in this project a screaming siren lights circuit is presented. Screaming siren lights

are those which produces siren depending on the light intensity falling on the circuit. We can

also call it as Laser Based Security alarm as it is a Light Activated Alarm circuit.

The circuit illustrated here is a burglar alarm. LDR is place at such a place that when the thief

enters our house then a connection of beam of light and LDR is disrupted by the intruder and

the buzzer goes off.

When a ray of light is interrupted by anything, the LDR used in the circuit changes its

resistance and causes the buzzer to go off, producing a large siren, scaring the intruders away.

Circuit can be easily modified to make the police siren a simple alarming sound. If once the

alarm circuit is on it will still ringing until push the reset button. There is two option of

ringing. One is the duration of ringing depends on preset timer and another reset manually. If

anybody wants to bind a sensitive area with the single ray he has to use mirror at every corner

to reflect it. The system has built with low cost and high performance. The power

consumption of the system is very low.

2

It is of interest, in regard to future laser communication links, to discuss the question of

whether the information transmitted along a narrow line-of-sight path to a receiver is proof

against interception. The automatic assumption that a beam of light whose beam diameter is

of the order of magnitude of the collector mirrors is “secure” in principle is strictly true only

for propagation in empty space. In transmission through the atmosphere, scattering

phenomena due to water droplets in fog, cloud or rain, ice crystals, snowflakes, dust particles,

and Rayleigh scattering from the air molecules themselves produce diffusion of the light from

the direct path of the beam. This diffused light can be detected and utilized.

1.1 Aim

To main aim of Laser Security Alarm is-

Totally reduces man power.

Prevent the entry of unauthorized person in the particular area.

And also improve the security system.

To provide a very modern and high sensitive system.

1.2 Features of System

Easy installation and low maintenance.

Fully automatic, saves man power.

Consume very low energy and provides flexibility in operations.

1.3 System components

Laser light

LDR

N-P-N Transistors

LEDs

Laser receiver

Timer IC-555

Counter IC

Seven Segment Display

Resistors and Capacitors

Beeper

Wire and PCB

3

4

CHAPTER-2

LASER

The term "laser" originated as an acronym for "light amplification by stimulated emission of

radiation".

A laser differs from other sources of light in that it emits light coherently. Spatial coherence

allows a laser to be focused to a tight spot, enabling applications such as laser cutting and

lithography.

Spatial coherence also allows a laser beam to stay narrow over great distances (collimation),

enabling applications such as laser pointers. Lasers can also have high temporal coherence,

which allows them to emit light with a very narrow spectrum, i.e., they can emit a single

color of light. Temporal coherence can be used to produce pulses of light as short as a

femtosecond.

Among their many applications, lasers are used in optical disk drives, laser printers, and

barcode scanners; fiber-optic and free-space optical communication; laser surgery and skin

treatments; cutting and welding materials; military and law enforcement devices for marking

targets and measuring range and speed; and laser lighting displays in entertainment.

We are using a 5 volt laser in this project.

Fig-2.1 (5 volt laser)

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2.1 Working Principle of Laser

The working principle of laser is depending on the stimulated emission of electromagnet light

which is describing as below.

The energy of an electron orbiting an atomic nucleus is larger for orbits further from the

nucleus of an atom. However, quantum mechanical effects force electrons to take on discrete

positions in orbital. Thus, electrons are found in specific energy levels of an atom, two of

which are shown below:

Fig-2.2 (Stimulated Emission)

When an electron absorbs energy either from light (photons) or heat (phonons) it receives that

incident quantum of energy. But transitions are only allowed in between discrete energy

levels such as the two shown above. This leads to emission lines and absorption lines.

When an electron is excited from a lower to a higher energy level, it will not stay that way

forever. An electron in an excited state may decay to a lower energy state which is not

occupied, according to a particular time constant characterizing that transition. When such an

electron decaying without external influence emitting a photon.

That is called "spontaneous emission". The phase associated with the photon that is emitted is

random. A material with many atoms in such an excited state may thus result in radiation

which is very spectrally limited (centered on one wavelength of light) but the individual

photons would have no common phase relationship and would emanate in random directions.

This is the mechanism of fluorescence and thermal emission.

6

An external electromagnetic field at a frequency associated with a transition can affect the

quantum mechanical state of the atom. As the electron in the atom makes a transition between

two stationary states (neither of which shows a dipole field) it enters a transition state which

does have a dipole field, and which acts like a small electric dipole, and this dipole oscillates

at a characteristic frequency.

In response to the external electric field at this frequency, the probability of the atom entering

this transition state is greatly increased.

Thus, the rate of transitions between two stationary states is enhanced beyond that due to

spontaneous emission. Such a transition to the higher state is called absorption, and it

destroys an incident photon (the photon's energy goes into powering the increased energy of

the higher state).

A transition from the higher to a lower energy state, however, produces an additional photon;

this is the process of stimulated emission.

7

CHAPTER-3

LIGHT DEPENDENT RESISTOR

A photo resistor is an electronic component whose resistance varies as a function of light.

The value of electrical resistance of a LDR is low when there is light shining on it (can drop

to 50 ohms) and high when it is dark (several mega ohms).Its operation is based on the

photoelectric effect. A photo resistor is made of a high resistance semiconductor such as

cadmium sulfide (CdS). If the light falling on the device is high- frequency photons are

absorbed by the semiconductor elasticity giving the electrons enough energy to jump the

conduction band. The resulting free electron and its associated gap, conduct electricity, so

that the resistance decreases. Typical values range from 1 MW or more in the dark and 100 Ω

in bright light. The cadmium sulfide cells are based on the ability to vary its resistance

cadmium according to the amount of light striking the cell. More light is incident, the lower

the resistance. The cells are also capable of reacting to a broad range of frequencies,

including infrared (IR), visible.

0

Fig-3.1 (Light dependent resistance)

3.1 Working Principle of LDR

Light dependent resistor works on the principle of photo conductivity. Photo conductivity is

an optical phenomenon in which the materials conductivity is increased when light is

absorbed by the material.

When light falls i.e. when the photons fall on the device, the electrons in the valence band of

the semiconductor material are excited to the conduction band. These photons in the incident

light should have energy greater than the band gap of the semiconductor material to make the

electrons jump from the valence band to the conduction band. Hence when light having

8

enough energy strikes on the device, more and more electrons are excited to the conduction

band which results in large number of charge carriers.

The result of this process is more and more current starts flowing through the device when

the circuit is closed and hence it is said that the resistance of the device has been decreased.

This is the most common working principle of LDR.

3.2 Characteristics of LDR

LDR' are light dependent devices whose resistance is decreased when light falls on them and

that is increased in the dark. When alight dependent resistor is kept in dark, its resistance is

very high. This resistance is called as dark resistance.

It can be as high as 1012 Ω and if the device is allowed to absorb light its resistance will be

decreased drastically. If a constant voltage is applied to it and intensity of light is increased

the current starts increasing. Figure below shows resistance vs. illumination curve for a

particular LDR.

Fig-3.2 (Characteristic of LDR)

Photocells are non-linear devices. There sensitivity varies with the wavelength of light

incident on them. Some photocells might not at all response to a certain range of

wavelengths. Based on the material used different cells have different spectral response

curves.

9

CHAPTER-4

LIGHT EMITTING DIODE

A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction

diode, which emits light when activated. When a suitable voltage is applied to the leads,

electrons are able to recombine with electron holes within the device, releasing energy in the

form of photons.

This effect is called electroluminescence, and the color of the light (corresponding to the

energy of the photon) is determined by the energy band gap of the semiconductor.

Fig-4.1 (Electronic symbol of LED)

4.1 Working Principle of LED

Fig-4.2 (The inner working of an LED)

A P-N junction can convert absorbed light energy into a proportional electric current. The

same process is reversed here (i.e. the P-N junction emits light when electrical energy is

applied to it). This phenomenon is generally called electroluminescence, which can be

defined as the emission of light from a semi-conductor under the influence of an electric

field.

10

The charge carriers recombine in a forward-biased P-N junction as the electrons cross from

the N-region and recombine with the holes existing in the P-region. Free electrons are in the

conduction band of energy levels, while holes are in the valence energy band. Thus the

energy level of the holes will be lesser than the energy levels of the electrons.

Some portion of the energy must be dissipated in order to recombine the electrons and the

holes. This energy is emitted in the form of heat and light.

The electrons dissipate energy in the form of heat for silicon and germanium diodes but in

gallium arsenide phosphide (GaAsP) and gallium phosphide (GaP) semiconductors, the

electrons dissipate energy by emitting photons.

If the semiconductor is translucent, the junction becomes the source of light as it is emitted,

thus becoming a light-emitting diode, but when the junction is reverse biased no light will be

produced by the LED and, on the contrary, the device may also be damaged.

Fig-4.3 (LED')

11

CHAPTER-5

BASIC COMPONENTS OF SYSTEM

5.1 Proto Board and connection board

This board, we will use the first part of the mounting system. Once we get the certainty that

the system works properly, we can make the final connection, which will alarm inside a

container. In this way this alarm will be portable.

A proto board is a board with holes electrically connected together, usually in patterns of

lines, which can be inserted and electronic components and wires for assembling electronic

circuit prototyping and similar systems.

It is made of two materials, insulation, usually a plastic, and a conductor connecting together

the various holes. One of its main uses is the creation and testing of prototype electronic

circuits before reaching the mechanical printing circuit in commercial production systems.

It is currently one of the most used test plates. Block is comprised of perforated plastic and

numerous thin films of an alloy of copper, tin and phosphorous, joining said perforations,

creating a series of parallel conducting lines.

The lines intersect at the center of the block to ensure that integrated circuit devices such dual

in-line package (DIP) can be inserted perpendicularly and without being touched by the

supplier to the conductive lines.

Fig-5.1 (Proto board and connection board)

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5.2 Resistor

Resistor called electronic component designed to introduce a specific electrical resistance

between two points of an electrical circuit. In the electrical and electronic slang itself, are

known simply as resistors. In other cases, such as plates, heaters, etc... Resistors are used to

produce heat exploiting the Joule effect.

It is a material comprising carbon and other resistive elements for decreasing the current

passing. He opposes the passage of current. The maximum current and maximum potential

difference across a resistor is determined by the maximum power that can dissipate your

body.

This power can be visually identified from the diameter without other indication is

necessary. The most common values are 0.25 W, 0.5 W and 1 W .There are variable value

resistors, which are called potentiometers or Variable Resistors.

Fig-5.2 (Electronic symbol of resistor)

5.3 Variable Resistor

It is an electronic component. It is applied in an electronic circuit for adjusting circuit

resistance to control voltage or current of that circuit or part of that circuit. The electrical

resistance is varied by sliding a wiper contact along a resistance track. Sometimes the

resistance is adjusted at present value as required at the time of circuit building by adjusting

screw attached to it and sometimes resistance can be adjusted as when required. The active

resistance value of the variable resistor depends upon the position of the slider contact on the

resistance track.

It mainly consists of a resistance track and a wiper contact. The wiper contact moves along

the resistance track when adjustable component is adjusted. There are mainly three different

types of resistance track used in this resistor they are carbon track, cermet (ceramic and metal

mixture) track and wire wound track. Carbon track and cermet track are used for high

13

resistance application whereas wire wound track is used for low resistance variable resistor.

The resistance tracks generally are of circular shape but straight track is also used in many

cases.

Fig-5.3 (Variable Resistor)

5.4 Precision resistors

Precision resistors or metal sheets , also known by its English name foil resistors are those

whose value is adjusted with errors 100 parts per million or less and also have a very small

variation with temperature of the order of 10 parts per million between 25 and 125 degrees

Celsius. This component has a special use in analog circuits with very tight specifications

settings. The resistance achieved such high precision in value, and temperature specification,

because it must be considered as a system, where materials that behave interact to achieve

stability.

A very thin metal sheet is glued to an insulator such as glass or ceramic, as the temperature

increases, the thermal expansion of metal is higher than that of glass or ceramic and being

attached to the insulator, the metal produces a force that compressed by reducing the

electrical resistance, and the coefficient of variation of resistance with temperature of the

metal is almost always positive, the almost linear sum of these factors, the resistance does not

change or do so minimally.

This component has its origin in several countries and at different times. By the 50s, some

companies and academic centers of technology, especially in the United States, began to

investigate new techniques for components to adapt to the emerging semiconductor industry.

The new electronic system should be more stable and more compact and industry of that time

placed more emphasis on the accuracy and stability of the behavior with temperature

changes.

14

In the technology were two emerging type resistors, the resistors can made of very thin metal

films deposited on insulating substrates such as glass or ceramics, and which reservoir is

performed with metal evaporation techniques.

Then there were resistors made from metal sheets whose thicknesses were greater than those

made with metal films. The metal sheets were glued to insulating substrates such as glass or

ceramics.

In our project we are using 100 and 330Ω resistor.

Fig-5.4(Resistor)

5.5 Color code

To characterize a resistor requires three values: electrical resistance, high accuracy or

dissipation and tolerance.

These values are normally used in the encapsulation according to the type thereof for axial

type of encapsulation that seen in the photographs, these values are labeled with a code of

colored stripes.

These values are indicated by a set of colored stripes on the body element. Three, four and

five lines leaving stripe tolerance (usually silver or gold) to the right, red from left to right.

The last line indicates the tolerance (precision). Of the remainder, the last is the multiplier

and the other figures indicate significant resistance value.

The electrical resistance value is obtained by reading the figures as a number of one, two or

three digits; is multiplied by the multiplier and the result is obtained in Ohms (Ω).

The temperature coefficient applies only high precision resistors or less tolerance of 1 %.

15

Fig-5.5 (Color Codes for Resistances)

5.6 Capacitor

A capacitor (originally known as a condenser) is a passive two-terminal electrical

component used to store electrical energy temporarily in an electric field.

Fig-5.6 (capacitor)

A capacitor consists of two conductors separated by a non-conductive region. The non-

conductive region is called the dielectric. In simpler terms, the dielectric is just

an electrical insulator. Examples of dielectric media are glass, air, paper, vacuum, and

even a semiconductor depletion region chemically identical to the conductors. A

capacitor is assumed to be self-contained and isolated, with no net electric charge and no

influence from any external electric field. The conductors thus hold equal and opposite

16

charges on their facing surfaces, and the dielectric develops an electric field. In SI units,

a capacitance of one farad means that one coulomb of charge on each conductor causes a

voltage of one volt across the device.

An ideal capacitor is wholly characterized by a constant capacitance C, defined as the

ratio of charge ±Q on each conductor to the voltage V between them:

𝐶 =𝑄

𝑉

5.7 Types of Capacitor

Fig-5.7 (Categories of Capacitor)

5.7.1 Ceramic Capacitors

A is ceramic capacitors a non-polarized fixed capacitor made out of two or more

alternating layers of ceramic and metal in which the ceramic material acts as the

dielectric and the metal acts as the electrodes.

The ceramic material is a mixture of finely ground granules of ferroelectric materials,

modified by mixed oxides that are necessary to achieve the capacitor's desired

characteristics. The electrical behavior of the ceramic material is divided into two

stability classes:

17

5.7.2 Film Capacitors

Film capacitors are non-polarized capacitors with an insulating plastic film as the

dielectric. The dielectric films are drawn to a thin layer, provided with metallic

electrodes and wound into a cylindrical winding. The electrodes of film capacitors may

be metalized aluminum or zinc, applied on one or both sides of the plastic film, resulting

in metalized film capacitors or a separate metallic foil overlying the film, called film/foil

capacitors.

Metalized film capacitors offer self-healing properties. Dielectric breakdowns or shorts

between the electrodes do not destroy the component. The metalized construction makes

it possible to produce wound capacitors with larger capacitance values (up to 100 µF and

larger) in smaller cases than within film/foil construction.

A key advantage of every film capacitor's internal construction is direct contact to the

electrodes on both ends of the winding. This contact keeps all current paths very short.

The design behaves like a large number of individual capacitors connected in parallel,

thus reducing the internal ohmic losses.

5.7.3 Film Power Capacitors

The materials and construction techniques used for large power film capacitors mostly

are similar to those of ordinary film capacitors. However, capacitors with high to very

high power ratings for applications in power systems and electrical installations are often

classified separately, for historical reasons. The standardization of ordinary film

capacitors is oriented on electrical and mechanical parameters. The standardization of

power capacitors by contrast emphasizes the safety of personnel and equipment, as given

by the local regulating authority.

5.7.4 Electrolyte Capacitors

We had used electrolytic capacitors in our project. Electrolytic capacitors have a metallic

anode covered with an oxidized layer used as dielectric. The second electrode is a non-

solid (wet) or solid electrolyte. Electrolytic capacitors are polarized.

The anode is highly roughened to increase the surface area. This and the relatively high

permittivity of the oxide layer give these capacitors very high capacitance per unit

volume compared with film- or ceramic capacitors.

18

The permittivity of tantalum pent oxide is approximately three times higher than

aluminum oxide, producing significantly smaller components. However, permittivity

determines only the dimensions. Electrical parameters are established by the electrolyte's

material and composition.

Fig-5.8 (Electrolyte Capacitor)

The large capacitance per unit volume of electrolytic capacitors make them valuable in

relatively high-current and low-frequency electrical circuits, e.g. in power supply filters

for decoupling unwanted AC components from DC power connections or as coupling

capacitors in audio amplifiers, for passing or bypassing low-frequency signals and

storing large amounts of energy. The relatively high capacitance value of an electrolytic

capacitor combined with the very low ESR of the polymer electrolyte of polymer

capacitors, especially in SMD styles, makes them a competitor to MLC chip capacitors

in personal computer power supplies.

19

CHAPTER-6

ALARM OR BUZZER

The alarm that we build is a laser light sensitive alarm. This means that the alarm will be

activated when the laser light is interrupted.

It is an alarm that is fed by electric current, so we are going to discuss the basic

principles of electricity.

6.1 Voltage

The potential difference between two points (1 and 2) of an electric field is equal to the

work done by the unit of positive charge to transport from point 1 to point 2. Voltage can

be defined as the electromotive force that causes free electrons move.

6.2 Electric Current

Is the electrical charge passing through a conductor section or unit of time? In the

International System of Units is expressed in coulombs per second, unit called ampere. If

the current is constant over time is said that the current is continuous; otherwise called

variable. If no storage or charge distribution occurs at any point of the conductor, the

current is stationary. According to Ohm's law, the intensity of the current is equal to

divided by the reluctance bodies' voltage:

𝐈 =𝐕

𝐑

6.3 Ohm's Law

As the electrical resistance in a circuit is very important in determining the intensity of

the flow of electrons, it is clear that it is also very important for the quantitative aspects

of electricity. It was long ago discovered that, other things being equal, an increase in

circuit resistance is accompanied by a decrease in current.

A precise statement of this relationship had to wait until reasonably certain as

instruments were developed. In 1820, Georg Simon Ohm, a teacher of German school,

found that the current in a circuit was directly proportional to the potential difference

20

produced by the current, and inversely proportional to the resistance limits the current. It

is expressed mathematically as we have seen before.

Voltage Potential difference (V) Volts. Current (I) Amps Resistance (R) Ohms

Fig-6.1 (5 volt buzzer)

21

CHAPTER-7

VOLTAGE REGULATOR

A voltage regulator is designed to automatically maintain a constant voltage level. A

voltage regulator may be a simple "feed-forward" design or may include negative

feedback control loops. It may use an electromechanical mechanism, or electronic

components. Depending on the design, it may be used to regulate one or

more AC or DC voltages.

Electronic voltage regulators are found in devices such as computer power

supplies where they stabilize the DC voltages used by the processor and other elements.

In automobile alternators and central power station generator plants, voltage regulators

control the output of the plant. In an electric power distribution system, voltage

regulators may be installed at a substation or along distribution lines so that all customers

receive steady voltage independent of how much power is drawn from the line.

We had used 7805 voltage regulator IC to convert 9V DC supply to 5V DC supply.

Fig-7.1 (voltage Regulator)

7.1 7805 Voltage Regulator IC

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear

voltage regulator ICs. The voltage source in a circuit may have fluctuations and would

not give the fixed voltage output.

22

The voltage regulator IC maintains the output voltage at a constant value. The xx in 78xx

indicates the fixed output voltage it is designed to provide. 7805 provides +5V regulated

power supply.

Capacitors of suitable values can be connected at input and output pins depending upon

the respective voltage levels.

Fig-7.2 (Pin Diagram)

7.2 Pin Description

Pin

No Function Name

1 Input voltage (5V-18V) Input

2 Ground (0V) Ground

3 Regulated output; 5V (4.8V-5.2V) Output

7.3 Working of IC 7805

ICs regulator is mainly used in the circuit to maintain the exact voltage which is followed

by the power supply. A regulator is mainly employed with the capacitor connected in

parallel to the input terminal and the output terminal of the IC regulator.

For the checking of gigantic alterations in the input as well as in the output filter,

capacitors are used. While the bypass capacitors are used to check the small period

spikes on the input and output level.

Bypass capacitors are mainly of small values that are used to bypass the small period

pulses straightly into the Earth.

23

Fig-7.3 (7805 Voltage Regulator Circuit)

24

CHAPTER-8

TIMER IC 555

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse

generation, and oscillator applications. The 555 can be used to provide time delays, as an

oscillator, and as a flip-flop element.

Depending on the manufacturer, the standard 555 package includes 25 transistors, 2

diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package

(DIP-8).

Low-power versions of the 555 are also available, such as the 7555 and CMOS TLC555.

The 7555 is designed to cause less supply noise than the classic 555 and the

manufacturer claims that it usually does not require a "control" capacitor and in many

cases does not require a decoupling capacitor on the power supply.

Those parts should generally be included, however, because noise produced by the timer

or variation in power supply voltage might interfere with other parts of a circuit or

influence its threshold voltages.

8.1 Pin Configuration

Fig-8.1(Pin diagram of IC-555)

25

The connection of the pins for a DIP package is as follows:

Pin Name Purpose

1 GND Ground reference voltage, low level (0 V)

2 TRIG

The OUT pin goes high and a timing interval starts when this input falls

below 1/2 of CTRL voltage (which is typically 1/3 VCC, CTRL being

2/3VCC by default if CTRL is left open).

3 OUT This output is driven to approximately 1.7 V below +VCC, or to GND.

4 RESET

A timing interval may be reset by driving this input to GND, but the

timing does not begin again until RESET rises above approximately 0.7

volts. Overrides TRIG which overrides THR.

5 CTRL Provides "control" access to the internal voltage divider (by default,

2/3VCC).

6 THR The timing (OUT high) interval ends when the voltage at THR

("threshold") is greater than that at CTRL (2/3 VCC if CTRL is open).

7 DIS Open collector output which may discharge a capacitor between intervals.

In phase with output.

8 VCC Positive supply voltage, which is usually between 3 and 15 V depending

on the variation.

26

Pin 5 is also sometimes called the CONTROL VOLTAGE pin. By applying a voltage to

the CONTROL VOLTAGE input one can alter the timing characteristics of the device.

In most applications, the CONTROL VOLTAGE input is not used. It is usual to connect

a 10nF capacitor between pin 5 and 0 V to prevent interference. The CONTROL

VOLTAGE input can be used to build an unstable multi-vibrator with a frequency-

modulated output.

8.2 Working and Circuit Diagram of IC 555

Fig-8.2 (Circuit Diagram of IC 555)

The internal resistors act as a voltage divider network, providing (2/3)Vcc at the non-

inverting terminal of the upper comparator and (1/3)Vcc at the inverting terminal of the

lower comparator. In most applications, the control input is not used, so that the control

voltage equals +(2/3) VCC.

Upper comparator has a threshold input (pin 6) and a control input (pin 5). Output of the

upper comparator is applied to set (S) input of the flip-flop. Whenever the threshold

voltage exceeds the control voltage, the upper comparator will set the flip-flop and its

output is high.

27

A high output from the flip-flop when given to the base of the discharge transistor

saturates it and thus discharges the transistor that is connected externally to the discharge

pin 7.

The complementary signal out of the flip-flop goes to pin 3, the output. The output

available at pin 3 is low. These conditions will prevail until lower comparator triggers

the flip-flop. Even if the voltage at the threshold input falls below (2/3) VCC that is upper

comparator cannot cause the flip-flop to change again. It means that the upper

comparator can only force the flip-flop’s output high.

To change the output of flip-flop to low, the voltage at the trigger input must fall below +

(1/3) Vcc. When this occurs, lower comparator triggers the flip-flop, forcing its output

low. The low output from the flip-flop turns the discharge transistor off and forces the

power amplifier to output a high.

These conditions will continue independent of the voltage on the trigger input. Lower

comparator can only cause the flip-flop to output low.

From the above discussion it is concluded that for the having low output from the timer

555, the voltage on the threshold input must exceed the control voltage or + (2/3) VCC.

This also turns the discharge transistor on. To force the output from the timer high, the

voltage on the trigger input must drop below + (1/3) VCC. This turns the discharge

transistor off.

A voltage may be applied to the control input to change the levels at which the switching

occurs. When not in use, a 0.01n Farad capacitor should be connected between pin 5 and

ground to prevent noise coupled onto this pin from causing false triggering.

Connecting the reset (pin 4) to a logic low will place a high on the output of flip-flop.

The discharge transistor will go on and the power amplifier will output a low. This

condition will continue until reset is taken high. This allows synchronization or resetting

of the circuit’s operation. When not in use, reset should be tied to +VCC.

28

CHAPTER-9

SEVEN SEGMENT DISPLAY (SSD)

A seven-segment display (SSD) or seven-segment indicator is a form of

electronic display device for displaying decimal numerals that is an alternative to the

more complex dot matrix displays.

Fig-9.1 (Seven segment led display)

Seven-segment displays are widely used in digital clocks, electronic meters, basic

calculators, and other electronic devices that display numerical information.

9.1 Basic Component

The seven elements of the display can be lit in different combinations to represent

the Arabic numerals. Often the seven segments are arranged in an oblique (slanted)

arrangement, which aids readability.

In most applications, the seven segments are of nearly uniform shape and size (usually

elongated hexagons, though trapezoids and rectangles can also be used), though in the

case of adding machines, the vertical segments are longer and more oddly shaped at the

ends in an effort to further enhance readability.

The numerals 6, 7 and 9 may be represented by two or more different glyphs on seven

segment displays, with or without a 'tail'.

29

The seven segments are arranged as a rectangle of two vertical segments on each side

with one horizontal segment on the top, middle, and bottom. Additionally, the seventh

segment bisects the rectangle horizontally.

Fig-9.2 (Seven segments of display)

There are also fourteen-segment displays and sixteen-segment displays (for

full alphanumeric); however, these have mostly been replaced by dot matrix displays.

The segments of a 7-segment display are referred to by the letters A to G, where the

optional decimal point (an "eighth segment", referred to as DP) is used for the display of

non-integer numbers.

30

CHAPTER- 10

TRANSISTOR

A transistor is fundamental building block of modern electronics devices. A transistor is

a device that regulates current or voltage flow and acts as a switch or gate for electronic

signals.

Fig-10.1 (Typical Transistor View)

Transistors consist of three layers of a semiconductor material, each capable of carrying

a current. A transistor is a semiconductor device used to amplify or switch electronics

signals and electrical power.

It is composed 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

through another pair of terminals.

Transistors are commonly used in digital circuits as electronic switches which can be

either in an "on" or "off" state, both for high-power applications such as switched-mode

power supplies and for low-power applications such as logic gates.

Important parameters for this application include the current switched, the voltage

handled, and the switching speed, characterized by the rise and fall times.

31

10.1 Types of Transistor

10.1.1 Bipolar Junction Transistor

The bipolar junction transistor is made primarily on a single crystal of germanium,

silicon or gallium arsenide, which have qualities of semiconductors, conductors as

intermediate between metals and insulators as diamond. On the glass substrate, are

contaminated in very controlled three zones, two of which are the same type, N-P-N or

P-N-P, they formed two P-N junctions being.

The N donor elements consists electrons (negative charges) and P acceptors area or

"holes" (positive charges). Usually P used as acceptors elements to Indio (In), aluminum

(Al) or gallium (Ga) and N donors Arsenic (As) or phosphorus (P).

The configuration of P-N junctions, give as transistors result PNP or N-P-N, where the

middle letter always corresponds to the characteristic of the base, and the other two to

the emitter and collector, although they are the same type and opposite to the base, have

different contamination between them (typically, the emitter is much more polluted than

the collector). The mechanism that represents the semiconductor behavior depends on

such pollution, the associated geometry and type of technology pollution (gaseous

diffusion, epitaxial, etc...).

10.1.2 Field Effect Transistor

The field effect transistor junction (JFET) was the first field effect transistor in practice.

It forms a bar of semiconductor material of N-type silicon or Q. terminal bar establishes

an ohmic contact, and have a transistor of N-type field effect of the most basic form.

If two P regions are disseminated in a bar of material N and connected externally to each

other, a door will occur. One of these contacts will call another Supplier and drain.

Applying positive voltage between the drain and the source and connecting door to the

supplier.

Fig-10.2 (Typical MOSFET)

32

10.2 BC-548 TRANSISTOR

The BC-548 is general purpose N-P-N bipolar junction transistor commonly used in

European electronic equipment. It is notably often the first type of bipolar transistor

hobbyists’ encounter, and is often featured in designs in hobby electronics magazines

where a general-purpose transistor is required. The BC-548 is low in cost and widely

available.

The strengths and weaknesses of the BC-548 transistor are derived mainly from its

design. A transistor at its most basic consists of a semiconductor material, a number of

terminals referred to as leads, and an overall packaging or enclosure. Like many similar

designs, the BC-548 transistor has three leads that connect to the rest of a circuit. This

makes it a bipolar junction transistor; the other main type of transistors is known as field-

effect transistor.

Each lead - respectively the collector, base, and emitter serves a different purpose.

Electric charge will flow from the collector through the base to the emitter at varying

levels, depending on the level of current in the base. This level is determined by the type

of semiconductor material used in the transistor.

Fig-10.3 (BC-548 Transistor)

33

CHAPTER-11

ANALOG COUNTER

CD-4033 is a Johnson counter IC commonly used in digital display. It has a 5 stage

Johnson decade counter with decoder which convert the Johnson code to a 7 segment

decoded output. Means it will convert the input into numeric display which can be seen

on 7 segment display or with the help of LED.

Advantage of this IC is it can be operated at high voltage of 20V. But is highly sensitive,

can detect emf present in the atmosphere and is sensitive to static charge also. When you

touch your finger at its input terminal its counter get started therefore care should be

taken while using it. It can be used in various applications like in 7 segments decimal

display circuit, in clocks, timer etc.

11.1 Pin Configuration and Functional Diagram

Fig-11.1 (Pin diagram of CD-4033 IC)

Pin 1 known as Clock in - It receives clock signals, and at every positive clock counter

advances one by one. You can provide clock with the switch, 555 timers or with the help

of logic gates.

Pin 2 known as Clock inhibit - CD-4033 counter advances one by one by receiving

positive pulse at this time clock inhibit pin should be grounded.

34

Pin 3 and pin 4 known as Ripple blanking in and Ripple blanking - It is used to

display only one zero blanking the other zero. For this IC have ripple blanking in and

ripple blanking out. For example you want to display 345 and you are using five 7

segment display then it will display 00345 if blanking input and out is off. But if it is on

than you will receive 345. It improves the readability of the circuit.

Pin 5 known as carry out - It is used to complete one cycle for every 10 clock input

cycle and it also used to cascade more IC's.

Pin 6, Pin 7 and Pin 9 to pin 13 - These are 7 decoded output from a to g used to

illuminates the corresponding segment of 7 segment display to display the digit from 0 to

Pin 14 known as Lamp test - It is used to check that all segments of 7 segment is

working properly or not. For testing momentarily make the pin low.

Pin 15 known as Reset - It is used to reset the counter. When it receives high it clears

the counter and counting again starts from zero. One important thing reset pin should

again made low to start the counter once again.

Pin 8 known as ground pin and Pin 16 known as Vdd it should be connected to power

supply.

11.2 INTERFACING 11.2.1 Interfacing with 7 Segment Display

The circuit describes below count numbers from 0 to 9 and display the same on 7

segment display. Whenever you press the switch, clock input receives the signals and its

counter advances one by one.

And it will count up to 9 and again start counting from 0 on each successive pressing of

switch. Pin configuration of 7 segment display can be obtained from the fig. shown

below.

Fig-11.2 (Interfacing of 7 segment display and IC-4033)

35

11.2.2 Interfacing with Timer IC 555

In the following circuit we have used a 555 timer in a stable oscillator mode to provide

clock signal to input of IC CD-4033 to start its counting which can be display on 7

segment displays. Here reset switch is used to reset the counting any time needed by the

user.

You can also interface two CD-4033 ICs if you want to increase the counting beyond 9.

This can be done by cascading 2 CD-4033 IC, connect the carry out of first IC to the

clock input of second IC. Now when first IC completes its counting than second IC will

start the counting. Connect reset pin of both the IC together and ground it with the help

of resistor.

36

CHAPTER-12

CIRCUIT DIAGRAM AND WORKING OF SYSTEM

There are two independent circuits one is Laser security alarm and another one is counter

system which are as follows-

12.1 Laser Circuit

Fig-12.1 (laser system circuit)

12.2 Working of Circuit

This is a remarkably easy LASER BASED SECURITY ALARM using only 4

components. A Transistor, resistor, LDR and a buzzer as an output signal.

A simple idea of potential divider circuit is used here. When the the light from the

source (LASER LIGHT) comes in contact with the LDR, its resistance decreases and

hence the voltage across it decreases.

There is a 1K Ohm resistor in series with the LDR so that the voltage across the 1K Ohm

resistor increases when the voltage across the LDR decreases. When the connection

breaks between the LASER and the LDR, the voltage across the LDR increases (as its

resistance increases) and that gives the input signal to the source and gate terminal of the

transistor and then the output from the drain terminal gives the input to the negative

37

terminal of the BUZZER, the positive terminal of the buzzer is connected to the Battery

itself. An LED can be added to the circuit in Parallel to the buzzer to indicate the output

signal in the form of LIGHT.

A resistor is used in series with the LED to limit the current through the led. A buzzer is

used instead of a speaker because of the low output POWER. The heart of the Circuit is

the N-P-N

The N-P-N transistor is used for low-power switching applications. It is a 60 V device,

capable of switching 200 mA , with a maximum on-resistance of 5 Ω at 10 V.A typical

use of this transistor is as a switch for moderate voltages and currents, including as

drivers for small lamps, motors, and relays. In switching circuits, this transistor can be

used much like bipolar junction transistors, but have some advantages: Low threshold

voltage means no gate bias required

12.3 Counter System Circuit

Laser counter circuit consists of:

1. Analog counter IC CD 4033

2. Timer IC 555

3. Seven segment display

4. Transistors

5. Voltage regulator

6. Light emitting diode

7. Capacitors & resistor

Fig-12.2 (Circuit diagram of counter System)

38

12.4 Working Laser Counter

In this circuit the IC 358 is working as a comparator and IC 555 is wired as a bistable

multi-vibrator. The transistor BC-548 is wired as a switch to provide the negative trigger

at pin 2 of 555. The 50K pot is used to adjust the sensitivity of the circuit.

When any one interrupts the laser beam, the LDR will go to darkness which increases the

resistance across LDR, which in turn increases the voltage across it. When the voltage at

Non-Inverting terminal (PIN 3) will greater than inverting terminal (PIN 2) the output of

the comparator goes high. Thus the output of transistor goes low and triggers the 555,

which sounds the buzzer. Here is the circuit diagram of a seven segment counter based

on the counter IC C. This circuit can be used in conjunction with various circuits where a

counter to display the progress adds some more attraction.

IC 555 is wired as an astable multi-vibrator for triggering the CD 4033. For each pulse

the output of CD 4033 advances by one count. The output of CD 4033 is displayed by

the seven segments LED.

39

CHAPTER-13

METHODOLOGY AND FUTURE SCOPE

The main part of this light activated alarm circuit is LDR and transistor. Transistor is

mainly used in switching applications. It produces the output required. This can be

operated in two modes. These two modes are off mode, on mode. In this circuit, it is

operated in both modes. In this mode no external triggering is required. One terminal

which is emitter connected to the +ve terminal of battery through the led and beeper

combination.

When light is strike at the LDR the transistor is remain in off mode and circuit complete

through 1K resistance and LDR. When the light of laser getting brake the transistor

comes in on mode than led will grow and beeper rings. This is all about the laser security

system.

The circuit mainly depends on the light dependent resistor for varying the sound in the

circuit. These are also called photo resistors. Generally, light dependent resistors will

have high resistance in darkness and it is decreased when they are illuminated with the

light.

The photo resistors used here are two mega ohm resistors i.e. they have resistance in the

range of mega ohms in darkness. In the present circuit, two resistors LDR and the 1K

ohm resistor are connected in series.

Speaker is another component that plays a vital role in the circuit. It takes the electrical

signals and translates it into physical signal. This acts as a transducer. Inside the speaker

there will a permanent magnet and the moving magnet.

These vibrations are heard at output. Here the speaker used is a buzzer. We have one

another circuit in our project it may be known is simple counter this circuit have a timer

IC 555 and a counter IC and seven segment display and resistances and capacitors to

make the operation of counting easy and safely. it also have a laser light which produce

the beam and strike at the laser receiver and when it is interrupted by any object the

display show the no. of brake of beam so we can see that how time laser beam is broken

by any object .IC 555 and counter IC and seven segments have interface in between.

40

This is all about the whole system which is capable the count the entry of threats to a

particular secured area.

The final product will be the model of "laser security alarm". The project model

consists of mainly two parts-

1. laser security alarm

2. person counter

Laser security alarm will notify that someone has trespassed secured area and analog

counter will give the count that how many persons have trespassed that particular area.

This project will give us effective protected area to us. Once this protected area will be

breached, the alarm will sound.

We made the laser security in low budget. It had been protect in full security. Laser

security systems are a high tech technology that used to be a part of home security only

available to the wealthy. It is manually switch dependent sensors and a basic alarm unit.

Laser has several advantages as compared to other light sources like cheap, less

manpower; efficient, easily available, design is quite easy.

41

REFERENCES

1. www.wikipedia.com 2. www.engineersgarage.com 3. www.mouserelectronics.com 4. www.allelectronics.com 5. www.digikey.com