Laser Project-edited 21

8/4/2019 Laser Project-edited 21

1/51

Laser torch based audio transmitter & receiver.

Department of electrical & electronics ~ 1 ~ February, 2011

LASER TORCH BASED AUDIO SIGNAL

TRANSMITTER AND RECEIVER

MINOR PROJECT REPORT

Submitted by

FARIS K.K

ROSHITH P.H

SAJEER P

BIJOY

SANKEERTH S

In partial fulfillment of the requirements for the

award of Degree of

BACHELOR OF TECHNOLOGY

IN

ELECTRICAL AND ELECTRONICS ENGINEERING

DEPARTMENT OF ELECTRICAL AND ELECTRONICS

ENGINEERING


2/51

Lase

torc

base audio trans itter & receiver.

Depart ent electrical & electr nics ~ 2 ~ Februar 2011

COLLE E O E EE T L E (Affiliated to CUSAT & Approved by A.I.C.T.E)

T L E , KANNUR.

COLLE E O ENGINEERING T ALASSERY

Electrical and Electronics Engineering Department

CERTI ICATE

Thii

tocerti

that the mi

or project report entitled

LASERTORCH BASE AUDIO SIGNAL

TRANSMI

TTER AND R

EC

EIV

ER

Sumitted by

FAR S K.K, R SH H P.H, SANKEER HS,

BIJOY & SAJEERP

I

a bonafide recordof the work done by themunderour supervision.

PROJECT GUIDE HEAD O THE DEPARTMENT


3/51



ACKNOWLEDGEMENT

We take this opportunity to express our deep sense of gratitude and

profound respect to all those who have guided and inspired us for the project

work.

We are deeply grateful to our Principal, Prof.P.V.SUGATHAN for

providing the facilities for our studies and constant encouragement in all

achievement.

We would like to express profound gratitude to our Head of the

department, Ms. Ashitha T, for her encouragement and for providing all

facilities for carrying out this project.

We express our highest regard and sincere thanks to our project

coordinator, Ms.Deepthi, who provided the necessary guidance and serious

advice to carry out this project. We also express our gratitude to our Project

Guide, Mr. Anith, for his apt suggestions and support.

We express our sincere thanks to all the staff members of the

department of Electrical and Electronics Engineering for their valuable advice

and encouragement that helped us a lot in successful completion of thisproject.

PROJECT TEAM


4/51



ABSTRACT

Light Amplification by Stimulated Emission of Radiation (LASER or laser) is

a mechanism for emitting electromagnetic radiation, often visible light, via the

process of stimulated emission

Communicating with laser is not new. We are all familia r with fiber optic

cables that carry our telephone signals from one place to another. The laser

beam here is used as a carrier, which is modulated by the signal to be

transmitted. On the receiver end the desired signal is separated from the

carrier. Here we are going to talk about a wireless laser link that could be

used to transmit information from one end to another in its line of sight.

Wireless laser communication links are very popular in space applications for

providing inters satellite communication.


5/51



CONTENTS

1. INTRODUCTION .06

2.BLOCK DIAGRAM..07

3.BLOCK DIAGRAM EXPLANATION....08

4. CIRCUIT DIAGRAM..10

5. COMPONENT TUDY....11

6. CIRCUIT DE CRIPTION....19

7. WORKING...21

8. PCB DE IGN AND FABRICATION.....22

9. COMPONENT LAYOUT .24

10. PRINTED CIRCUIT BOARD (PCB)LAYOUT..25

11.LI T OF TOOLS AND INSTRUMENTS REQUIRED...26

12. COMPONENTS REQUIRED....27

13. PRECAUTIONS....29

14. ADVANTAGES....30

15. DISADVANTAGES..31

16.PROBLEMS FACED .32

17.APPLICATIONS.. 33

18.CONCLUSION...34

19.REFERENCES...35

20.APPENDIX.36


6/51



1.INTRODUCTION

Laser as a communication medium can provide a good substitute

for the present day communication systems as the problem of

interference faced in case of electromagnetic waves is not there and

high deal of secrecy is available. Laser communications offers a viable

alternative to RF communications for inter satellite links and other

applications where high-performance links are a necessity. High data

rate, small antenna size, narrow beam divergence, and a narrow field of

view are characteristics of laser communications that offer a number of

potential advantages for system design. The present paper involves thestudy of wireless, open channel communication system using laser a

carrier for voice signals. Using this circuit we can communicate with

your own neighbors wirelessly. Instead of RF signals, light from a laser

torch is used as the carrier in the circuit. The laser torch can transmit

light up to a distance of about 500 meters. The phototransistor of the

receiver must be accurately oriented towards the laser beam from the

torch. If there is any obstruction in the path of laser beam, no sounds

will be heard from the receiver.


7/51



2.BLOCK DIAGRAM

AMPLIFIER SWITCHING

CIRCUITS

VISUAL

INDICATION

LASER

DIODE

PHOTO

TRANSISTOR AMPLIFIER

AUDIO

FREQUENCY

AMPLIFIER

LOUD

SPEAKER

GAIN

CONTROL

MIC


8/51



3. BLOCK DIAGRAM EXPLANATION

3.1CONDENSERMICROPHONE

It is also called a capacitor or electrostatic microphone. Condenser meanscapacitor, which stores energy in the form of an electric field. Condenser

microphones require power from a battery or external source. Condenser also

tends to be more sensitive and responsive than dynamic, making them well suited

to capturing subtle nuances in a sound.

The diaphragm vibrates when struck by sound waves, changing the distance

between the two plates and therefore changing the capacitance. Specifically when

the plates are closer together capacitance increases and a charge current occurs

and this current will be used to trigger the transmitting section .

3.2 TRANSMITTING SECTIONThe transmitter section comprises condenser microphone,

transistor amplifier BC548 followed by an op-amp stage built around

IC1. The gain of the op-amp can be controlled with the help of 1-mega

ohm pot meter VR1.The AF output from IC1 is coupled to the base of

transistor Bd139, which in turn, modulates the laser beam. The

transmitter uses 9V power supply. however, the 3-volt laser torch (

after the removal of its battery) can be directly connected to the circuit -

-with the body of the torch connected to the emitter of BD139 and the

spring-loaded lead protruding from inside the torch to circuit ground .

3.3 LASER TORCH

Here we use the light rays coming from laser torch as the medium for

transmission. Laser had potential for the transfer of data at extremely high rates,

specific advancements were needed in component performance and systems

engineering, particularly for space-qualified hardware. Free space laser

communications systems are wireless connections through the atmosphere. They

work similar to fiber optic cable systems except the beam is transmitted through

open space. The laser systems operate in the near infrared region of the

spectrum. The laser light across the link at a wavelength of between 780 920nm.


9/51



3.4 RECEIVING SECTION

The receiver circuit uses an NPN phototransistor as the light sensor that is

followed by a two stage transistor preamplifier and LM386 -based audio power

amplifier. The receiver doesn't need any complicated alignment. Just keep the

phototransistor oriented towards the remote transmitter's laser point and adjust the

volume control for a clear sound.

3.5 LOUD SPEAKER

A loudspeaker (or "speaker") is an electro acoustic transducer that converts

an electrical signal into sound. The speaker moves in accordance with the

variations of an electrical signal and causes sound waves to propagate through a

medium such as air or water.


10/51

Laser torc based audio trans itter & receiver.

Depart entof electrical & electronics ~ 10 ~ Februar 2011

4. CIRCUIT DIAGRAM

4.1 TRANSMITTER

4.2 RECEIVER


11/51


12/51


13/51



5.1.1.1 NEGATIVE EEDBACK CONTROL

Fig 5.1.1.1. Negative feedback control circuit

The e fi e hows the si i it, i l i the egati e feedback loop

of an op amp. The output is fed back to the inverting input terminal in order to

provide negative feedback for the amplifier. The input signal is applied to the

inverting input. Asaresult, theoutput will be inverted. It ispossible tooperate the

opampasanon-invertingamplifierbyapplying thesignal to theplus input. In this

circuit the feedbacknetwork isstill connected to the inverting input.

5.2 VR (potentiometer/resistance varies/trimmer):

Thepotentiometer isaresistorofvariableresistance. It has three terminals;a

fi edresistance is foundbetween twoof the terminalsand the third terminal slides

along the fi edresistor. ften, it isused tocontrol thevolume inanaudioamplifier.


14/51



5.3 CAPACITOR:Thecapacitorplaysacrucial role inelectronics -- it storeselectrons forwhen

they're needed most. apacitors consist of two conducting plates placed near

each other. Inside the capacitor, the terminals connect to two metal plates

separatedbyadielectric. Thedielectriccanbeair, paper, plasticoranythingelse

that doesnot conduct electricityandkeeps theplates from touchingeachother.

fig 5.3. Ceramic capacitor

They can store electric charge for later discharge. irect current through acapacitor will charge the capacitor for a short time, and then stop flowing.

Alternatingcurrent, becauseof thechangingelectric fields it generates, can flow

acrossacapacitor.

5.4 DIGITAL MULTIMETER (DMM)

The is an instrument that is able to measure voltage, current, and

resistance in a ircuit, or across circuit components and displays its

measurementsonadigital display.


15/51

Laser torc based audio trans ! itter & receiver.


5.5 BATTERY (9 VOLT)

It has two terminals. ne terminal ismarked + , orpositive, while theo ther

ismarked -), ornegative. Inanormal flashlight battery, theendsof thebatteryare

the terminals. Ina largecarbattery, thereare twoheavy leadposts that act as the

terminals.

Electrons collect on the negative terminal of the battery. If you connect a wire

between the negative and positive terminals, the electrons will flow from the

negative to thepositive terminal as fast as theycan andwearout thebatteryvery

uickly -- thisalso tends tobedangerous, especially with largebatteries, s o it is

not somethingyouwant tobedoing). ormally, youconnect some typeof load to

thebatteryusing thewire.

Fig 5.5: 9V Battery

5.6 LASERTORCH

Forthisproject wehaveremoved the laserassembly fromasmall laser

pointer. Thepowersupplycircuit is thegreenboardattached to thebrass laser

head. ecarrysimilarlaserpointers inourcatalog that areeasilydisassembled

forthisproject. Thepowersupplycircuit came convenientlymarkedwithaplus

andaminusnext to twoholes in theboard. esoldertheblacknegative lead from

thebatteryclip to theholemarkedminus. esolderoneof th ecoil leads to the

holemarkedplus. esoldertheredpositive leadof theb atterychip to theother

lead from thecoil.


16/51

Laser torc " based audio trans # itter & receiver.


Fig 3.7. Laser torch

5.7 MICROPHONEAll of the different sounds that we hearare caused by minute pressure

differences in theairaroundus. Theamazing fact about it is that theair transmits

thosepressurechangessowell, andsoaccurately, over relatively longdistances

A microphonewants to takevaryingpressurewaves in thea irandconverts them

intovaryingelectrical signals. There aredifferent technologiesused toaccomplish

thisconversion. euse ondensermic inourproject .

5.7.1 CONDENSER MICROPHONES

A condenser microphone is essentially a capacitor, with one plate of the

capacitormoving inresponse tosoundwaves .

5.8 INTEGRATED CIRCUIT (IC)An integratedcircuit isapre-madecircuit shrunkdown tosmall sizeandput

on a chip. I s save circuit makers time by serving common purposes like

amplifyinga signal whichwouldotherwisehave tobedonebyanewcircuit built

fromscratchevery time.


17/51

Laser torc $ based audio trans % itter & receiver.


5.9 PHOTOTRANSISTORS

The standard symbol of a phototransistor, which can be regarded as a

conventional transistorhoused inacase that enables itssemiconductor junctions

to be exposed to external light. The device is normally used with its base open

circuit, ineitherof theconfigurationsshown in fig. . . , and functionsas follows .

Fig. 5.9.1Phototransistor symbol.

In practice, the collector and emitter current of the transistor are virtually

identical and, since the base is open circuit, the device is not subjected to

significant negative feedback. The sensitivity of a phototransistor is typically one

hundred timesgreater than that ofaphotodiode, but isuseful maximumoperating

frequency a few hundred kilohertz) is proportionally lower than that of a

photodiodebyusingonly itsbaseandcollector terminalsand ignoring theemitter,

asshown in fig. . . . Phototransistorsaresolid-state light detectorswith internal

gain that are used to provide analog or digital signals. They detect visible,

ultraviolet andnear-infrared light fromavarietyofsourcesandaremoresensitive

than photodiodes, semiconductor devices that require a pre-amplifier.

Phototransistors feed a photocurrent output into the base of a small signal

transistor. For each illumination level, the area of the exposed collector -base

junctionand the current gainof the transistordefine t heoutput.


18/51

Laser torc & based audio trans ' itter & receiver.


Fig. 5.9.2. Phototransistor used in circuit

The base current from the incident photons is amplified by the gain of the

transistor, resulting in current gains that range from hundreds to several

thousands. esponse time is a function of the capacitance of the collector-base

junctionand thevalueof the loadresistance. Photodarlingtons, acommon typeof

phototransistor, have two stages of gain and can provide net gains greater than

, . Becauseof theireaseofuse, lowcost andcompatibilitywith transistor -

transistor logic TTL), phototransistorsareoftenused in applications where more

than several hundred nano watts nW) of optical power are available. Selecting

phototransistors requires an analysis of performance specifications. ollector

current is the total amount of current that flows into the collector terminal.

ollector dark current is the amount of collector current for which there is no

optical input. Typically, both collector current and collector dark current are

measured in milliamps mA). Peak wavelength, the wavelength at which

phototransistorsaremost responsive, ismeasured innanometers nm). ise time,

the time that elapses when a pulse waveform increases from % to % of its

maximum value, is expressed in nanoseconds ns). ollector-emitter breakdown

voltage is the voltage at which phototransistors conduct a specified

nondestructive) current when biased in the normal direction without optical or

electrical inputs to thebase.


19/51



6. CIRCUIT DESCRIPTION

There are two sections: the transmitter board and the receiver board, both

powered by a separate 9V battery or a fixed voltage power supply. The transmitter

board has a condenser microphone module at one end, and the laser diode at the

other end. The electronics modulates the intensity of the laser beam according to

the output of the microphone. The laser diode has an inbuilt collimating lens, and

is simply a module that connects to the transmitter board. The receiver uses a

phototransistor as the receiving element, and the onboa rd amplifier powers a small

8 ohm speaker. This board is therefore a high gain amplifier with a basic audio

output stage.

Since this design uses a higher power (and visible) laser beam, the range is

improved, and alignment is easier and not all that critical, espec ially over a few

hundred meters and hence get better results. The quality of sound transmitted by

the link is quite surprising. Clearly, this project is ideal for setting up a speech

channel between two areas, say adjacent houses or offices on opposite sides of

the street. Or you could use it as a link between the work shop and the house. For

duplex (two way) communication, you'll obviously need two laser 'channels. An

important feature of transmission by laser beam is privacy. Because a laser beam

is intentionally narrow, it's virtually impossible for someone to tap into the link

without you knowing. If someone intercepts the beam, the link is brok en, signaling

the interception. Fibre-optic cables also have high security, as it's very difficult to

splice into the cable without breaking the link. However it's theoretically possible;

so for the highest security, you probably can't beat a line -of-sight laser beam.

Where the transmission distance is no more than meter of so, a LED (or two

for increased power) can be substituted for the laser diode. For instance, where

the link is being used for educational purposes, such as demonstrating fibre -optic

coupling, or the concept of communication over a light beam. Obviously the

security of the transmission is much lower as LEDs transmit light in all directions.

While this laser link can be adapted for use as a perimeter protector. Now to a

description of how it all works. We'll start with the transmitter.


20/51



6.1TRANSMITTER

A laser diode needs a certain value of current, called the threshold current,

before it emits laser light. A further increase in this current produces a greater light

output. The relationship between output power and current in a laser diode is very

linear, once the current is above the threshold, giving a low distortion when the

beam is amplitude modulated.

Laser diodes are very fragile and will not survive electrostatic discharges and

momentary surges! However, if used within specifications, the typical life of one of

these lasers is around20,000 hours. In the transmitter circuit (Fig.1) the laser diode

is supplied via an adjustable constant-current source. Note that the metal housing

for the laser diode and the lens also acts as a heat sink. The laser di ode should

not be powered without the metal housing in place. The increasing the voltage at

VR1 reduces the laser current. The setting of VR1 determines the quiescent

brightness of the laser beam, and therefore the overall sensitivity of the system.

The electric microphone is powered through R1 and is coupled to the non inverting

input of 1C1 via a capacitor. This input is held at a fixed DC voltage to give a DC

output to bias.

6.2 RECEIVER

The transmitted signal is picked up by the photo detector transistor in the

receiver (shown inFig.2). The output voltage of this diode is amplified by the

common emitter amplifier around T4. This amplifier has a gain of 20 or so, and

connects via VR2 to IC2, anLM386 basic power amplifier IC with a gain internally

set to 20.This IC can drive a speaker with a resistance as low as four ohms, and

35OmW when the circuit is powered from a 9V supply. Increasing the supply

voltage will increase the output power marginally.


21/51



7. WORKING

In all of the laser communicators on this page, the laser light is amplitude

modulated. This simply means that the amount of light the laser emits varies over

time.

To understand what is going on, it helps to consider how a loudspeaker makes

sound. A loudspeaker is a paper cone attached to a coil of wire that sits in a

magnetic field from a strong permanent magnet. When an electric current flows in

the loudspeaker coil, the coil becomes an electromagnet, and it moves toward or

away from the permanent magnet. As it moves, the paper cone pushes on the air

around it, compressing the air in front of it, and expanding the air behind it. Wavesof compressed and expanded air travel to your ear, and cause your eardrum to

move in time to the movements of the paper cone. The laser communicator adds

two components to the loudspeaker concept. We take the electrical signal that

goes to the loudspeaker, and connect it instead to the laser, so the laser gets

brighter and dimmer as the electric current varies. The second component is the

receiver, which converts the light back into an electric current. This current varies

in time with the first current, because the amount of light that it receives is varying

in time. This second electric current is used to move the paper cone of a

loudspeaker, just as before. However, now the loudspeaker can be quite a

distance away from the original electric current, without any wires connecting the

two.


22/51



8. PCB DESIGN AND FABRICATION

8.1 PCB DESIGN

Designing of PCB is a major step in the production of PCB is a major. It forms a

distinct factor in electronic performance and reliability. The productivity of a PCB,

its assembly and service ability also depends on the design.

The designing of a PCB consists of designing of the layout followed by the

preparation of the artwork. The layout should include all the relevant aspects in

details of the PCB design while the art work preparation brings it to the form

required for the production process. The layout can be designed with the help of

anyone of the standard layout edition software such as Eagle, Orcad or Edwin XP.

Hence a concept, clearly defining all the details of the circuits and partly of the

equipment, is a prerequisite and the actual layout can start. Depending on the

accuracy required, the artwork might be produced a 1:1 or 2:1 even 4:1 scale. It is

best prepared on a 1:1 scale.

8.2 PCB FABRICATION

PCB fabrication involves the following steps.

1. First the layout of the PCB is generated using the software ORCAD. First

step involves drawing the circuit CIS which is a section of ORCAD. Then

the layout is obtained using layout plus. This layout is printed on a paper.

2. This printed layout is transferred to a Mylar sheet and t ouched with black

ink.

3. The solder side of the Mylar sheet is placed on the shining side of the

copper board and is placed in a frame. It is than exposed to sunlight, with

the Mylar sheet facing the sunlight.

4. The exposed copper board is put in hydrogen peroxide solution. It is then

put in hot water; shook till unexposed region becomes transparent.

5. This is put in cold water and then the rough side is struck in to the skill

screen. This is then pressed and dried well.


23/51

Laser torc ( based audio trans ) itter & receiver.


6. The plastic sheet of the five - star is removed leaving the pattern on the

screen.

. A copper clad sheet is cut to the size and cleaned. This is then placed

under thescreen.

. Acidresist ink isspreadon thescreen; So that thepatternof the tracksand

pad isobtainedon thecoppercladsheet. It isdried.

. The dried sheet is then etched using ferric chloride solution till all the

unwantedcopper isetchedaway.

.Theunwantedresist ink isremovedusingsodiumhydroxidesolution, holes

are thendrilled.

.Thecomponentsaresolderedneatlyon theboardwithout drysoldering

C0 1 1 2 3 CLA 4 LA 5 6 NA

7

2 DRILLING OF PCB :

PCB Soldering


24/51



9. COMPONENTS LAYOUT

9.1 TRANSMITTER 9.2 RECEIVER


25/51

Laser torc 8 based audio trans 9 itter & receiver.


10. PRINTED CIRCUITBOARD (PCB) LAYOUT

10.1 TRANSMITTER

10.2 RECEIVER


26/51



11. LIST OF TOOLS AND INTRUMENTS REQUIRED

Following tools and instruments are used for preparing the project

1. Soldering iron

2. Desoldering pump

3. Drill Machine

4. Multimeter

5. Filer

6. Tweezers

7. Screw driver

8. Dual power supply

9. Flux

10. Desoldering wick

11. Petrol

12. Brush

13. Soldering Wire


27/51



12. COMPONENTS REQUIRED

12.1 TRANSMITTER SECTION:

SI. No NAME OF T@

E COMPONENT QUANTITY

1. Resistance (8.2 K)2

2. Resistance(1.8 M)1

3. Resistance(10k)1

4. Resistance(15k)2

5. Resistance(82)1

6. Variable resistance (1 M)1

7. Capacitor(1F)16V1

8. Capacitor(0.1F)16V1

9. Capacitor(470F)16v1

10. Capacitor(1000F)16v1

11. Condenser mic1

12.

Transistor BC548

1

13. Transistor BD139 1

14. IC UA7411

15. 9v Battery1

16. 3v Laser torch1


28/51



12.2 RECEIVER SECTION:

SI.No NAME OF THE COMPONENT QUANTITY

1 Resistor(6.8k) 1

2 Resistor(2.2k) 2

3 Resistor(4.7k) 1

4 Resistor(470k) 1

5 Resistor(1k) 1

6 Resistor(10) 1

7 Variable Resistor(10k) 1

8 Capacitor(0.01F)16V 1

9 Capacitor(47pF)16V 1

10 Capacitor(100F)16V 2


12 Capacitor(0.1F)16V 2



15 Transistor BC549 2

16 Photo transistor LI4F1 1

17 IC LM386 1

18 Loud speaker 0.4W,8 1

19 9v Battery 1


29/51



13. PRECAUTIONS

1. Safety instructions for lasers: Laser beams may damage the eyes severely or

may cause blindness if they radiate into the eyes directly or indirectly. Therefore

the laser electronics must be installed in such a manner that radiation into the eyes

will be impossible neither directly nor indirectly via marrows in the room.

When using lasers with an output power higher than 1 mW, you should check

about the legal regulations for prevention of accidents and be very careful. Normal

laser pointers sold in shops have typically output power of 1.5 mW (power

depends on laser pointer model and what country regulations say on maximum

power). This power level is normally not very hazardous, but can cause permanent

dotages your eye if you stare at the beam.

We should be very careful with higher power lasers and lasers on that power

range that emit invisible radiation, because they can cause immediate eye damage

(and very high power lasers can cause skin burns or fire).With any high power

laser make sure that you have safe operating environment, necessary

regulations/permissions and somebody that takes care that these legal regulations

are observed. Lasers use coherent light which has very different properties to astandard lighting effect. This is what makes lasers one of the most beautiful forms

of light, but also one of the most dangerous light sources if not used with proper

cautions

2. In the transmitter schematic, no ballast resistor is shown because most small

LASER power supplies already have one built in. Yours may differ, and a resistor

maybe needed.

3. The receiver should be kept away from bright lights. You may put a piece of

wax paper in front of photo transistor to keep the LASER from swamping it.


30/51



14.ADVANTAGES

1. Less costly2. Circuit can be easily constructed

3. High data rate

4. No communication licenses required.

5. The laser transmission is very secure because it has a narrow beam.

6. There are no recurring line costs.

7. Compatibility with copper or fiber interfaces and no bridge or route r

requirements.

8. Lasers can also transmit through glass; however the physical properties ofthe glass have to be considered.

9. Narrow beam divergence

10.Laser transmitter and receiver units ensure easy, straightforward

systems alignment and long-term stable, service free operation,

especially in inaccessible environmen ts, optical wireless systems

offer ideal, economical alternative to expensive leased lin es for

buildings.


31/51



17. DISADVANTAGES

1. To avoid 50Hz hum noise in the speaker, keep the phototransistor away

from AC light sources such as bulbs. The reflected sunlight, however, does

not cause any problem. But the sensor should not directly face the sun.

2. It can be used only for a few meters.

3. Any obstructions in the LASER path cause distortion of audio signal.


32/51



18. PROBLEMS FACED

Although this project was successfully completed, however a few hurdles that

came during the construction of the circuit were the breaking of the thin electricalwires after it had been soldered

Moreover the connections with the OP-AMP chip have to be dealt with very

carefully because one wrong connection may damage the whole chip. If the supply

to laser is greater than it will not glow.

All these things are to be taken care of, for the efficient working of the project.


33/51



19. APPLICATIONS

1. Using this circuit we can communicate with our neighbors wirelessly

2. It can be used in inaccessible areas.3. In future it can be commissioned in satellites for communication.

4. It can be used in conference halls.


34/51



20. CONCLUSION

After the successful working of the project, it can be concluded that this

project is suitable for easily communication. There can be further up gradations inthe project which could lead to a much better system for communication. Some of

the possible ways are as follows:-

Instead of the short range laser, high range lasers can be used which range a few

hundred meters.

Provisions have to be made for cases when there is no heavy traffic.


35/51



21.REFERENCES

1. [Online] // Wikipedia. - www.wikipedia.com.2. [Online] // circuits today. - www.circuitstoday.com.

3. [Online] // electronics schematics. - www.electroschematic.com.

4. [Online] // electronics for you. - www.efy.com.

5. LINEAR INTEGRATED CIRCUITS [Book] D.ROY CHOUDHARY SHALIN

B. JAIN

6. ELECTRONICS FOR YOU MAGAZINE [Book].

7. ELECTRONICS DEVICE & CIRCUITS [Book] GUPTA J.B.

8. PRINCIPLES OF ELECTRONICS [Book]. MEHTA V.K.9. NAVAS K.A. ELECTRONICS LAB MANUAL [Book]. Vol. 1&2.


36/51

Laser torc A based audio trans B itter & receiver.


22.APPENDIX


37/51




38/51




39/51




40/51




41/51




42/51




43/51




44/51




45/51




46/51




47/51




48/51




49/51




50/51




51/51


Laser Project-edited 21

Documents