OPTICAL FIBRE COMMUNICATION

In this model we show the working of the optical fiber with the help of two-

amplifier circuit. In this model we transmit the data in analogue form. Firstly

we convert the sound signal into light signal. This light signal is coupled to

the optical fiber and end of the optical fiber is connected to photodiode.

Photodiode convert the light signal into electrical signal and this electrical

signal is now reproduced in to sound signal with the help of amplifier and

speaker.

In this project we use IC 741 as a amplifier component. Pin no 7 of

the IC is connected to the positive supply. Pin no 4 of the IC is connected to

the negative supply. Pin no 6 is output pin. Pin no 2 and 3 is input pin.

Positive and negative voltage is supply to the IC through battery. In this

project we use 9-volt dc voltage as a supply voltage. Pin no 3 is act as a

reference voltage pin, for this purpose we connect two resistance to pin no 3

via positive terminal and negative terminal..Input signal is applied to the pin

no2 via capacitor and input resistance. Input signal is applied to the pin no2

through condenser mike. Condenser mike converts the sound signal into

small electrical signal. This electrical signal is coupled to the pin no 2 via

capacitor and resistance. Here capacitor work as a DC blocking capacitor

and pass only AC signal from the mike. This input signal after coupling to

the pin no2 is amplified by the IC 741 and available on the pin no 6. Here

we connect a one feedback resistance between pin no 6 and pin2. This

resistance is work as a feedback resistance. Feedback resistance acts as a

very important part in this amplifier, After increasing the value of this

resistance we change the level of the sound. Now output from the pin no 6 is

coupled to the two transistor circuit. Here both transistor works as push pull

amplifier network circuit. Output of the transistor is connected to the L.E.D

through one resistance. Now sound is converted into light with the help of

this L.E.D Variations in the intensity of the light is as per the intensity of the

sound.

We coupled this light of the L.E.D to the optical fiber in proper way. We

connect it in optical fiber, so that all the light is pass through the optical fiber

in other end.

Now optical fiber is connected to the photodiode in proper way, so that all

the light is from optical fiber is connected to the photodiode is not wasted .

Photodiode is light sensitive component. Photodiode convert this light into

the small voltage. This small electrical signal is coupled to the pin no 2 of

the IC. Here again we use one operational amplifier as a amplifier circuit.

Pin no 7 of this IC is connected to the positive. Pin no 4 is connected to the

negative voltage. Pin no 6 is the output pin. Electrical signal amplify by the

IC is available on the pin no 6. Output from the IC is again amplify by the

pushpull amplifier circuit. Output from the push pull amplifier is now

connected to the speaker via capacitor. We use capacitor for block the dc

voltage from the IC and pass only AC signal to the speaker.

Digital transmission.

In this digital transmission we transmit the signal in digital

form. We transmit this data on the laser or small L.ED.. When we point the

laser beam on the receiver point then laser light develop a small

voltage in the photodiode and due to this laser light photodiode

convert this light into small voltage and further converted into

numeric display.. In the case of optical fibre we connect the light from

transmitter to one end of optical fibre and other end of the optical fibre is

connected to the photodiode.

In transmitter section we use 9 switches for the nine decimal

number’s and the output circuit we use one seven segment display

for the numeric display.

In transmitter section we use one DTMF signal generator for

generating a signal in the form of PWM pulse width modulation.

for this purpose we use ic UM 91513 as a transmitter. This UM

91513 is a commonly dtmf signal generator IC. All the nine

switches are connected to the input of this IC . All the

switches are connected together as a matrix network. All the

switches are divided in four row and three column. We indicate the

row as a R-1,R-2, R-3, R-4 and column as a C-1, C-2, C-3 . When

we press the switch no 1 then Pin no 15 and pin no 12 is activate

because pin no 15 is connected to the R-1 and pin no 12 is

connected to the C-1. Pin no 6 of this ic is connected to the

positive supply. This ic is very sensitive to voltage and require

only 3.3 voltage. for this purpose we use one zener diode

regulated power supply with this project. Resistance 150 ohm

limit the current and 3.3 volt zener regulate the input supply

voltage. One crystal is connected to pin no 3.579545 MHz is

connected to the pin no 3 and 4. this frequency is a carrier

frequency of this input pins. Output signal is available on the

pin no 7 of this ic. This output signal is directly connected to

the operational amplifier circuit. In this operational amplifier

we use ic 741 as a amplifier circuit. Input signal from the pin

no 7 of this ic is connected to the pin no 2 of the ic 741. Pin

no 3 act as a comparator. Pin no 6 is output pin. Pin no 7 is

connected to the positive supply and pin no 4 is connected to the

negative supply. One resistor is connected between pin no 6 and

pin no 2 to give a positive feedback. Output from the operational

amplifier is further amplified by the two transistor. We use two

transistor’s are here one is NPN and second is PNP. collector of

₃the npn is connected to the positive supply and collector of the

pnp is connected to the negative supply. Output is available from

the emitter of the both transistor. Output from the transistor is

further connected to the laser beam. Here we use Ga-as laser. In this laser

beam there is one semiconductor laser diode. Working voltage of this diode

is approx. 3.6 volt. This diode is very sensitive and on high voltage it is

immediately burnt out. Output from the amplifier is further again converted

into regu₃lated 3.6 voltage with the help of one 3.6 volt zener diode. Now

when we press any switch from the keyboard then ic generate a frequency

and this frequency is amplified by the operational amplifier and this signal is

further transmit by the laser beam in the form of the light.

In receiver circuit We use one photodiode. Photodiode is very senstive to

light . When light focus on the photodiode then photodiode sense the light

and convert it into a very small voltage. This small signal is amplified by the

operational amplifier and further connected to the DTMF decoder circuit.

DTMF decoder circuit receive signal from the operational amplifier and

convert this signal into a BCD signal.

For the DTMF decoder circuit we use IV 8870/9170. This a 16 pin IC. Pin

no 10 and 18 is connected to the positive supply. One crystal is connected to

the pin no 7 and 8 to demodulate the frequency. Signal from the operational

amplifier is applied to the pin no 2 and 3 of this ic. This ic Receive the signal

and demodulate the frequency and this frequency is available on the pin no

11,12,13,14 in the form of BCD signal. If we use this BCD signal in further

then we can control many electrical appliances through this circuit. But here

we display the numeric number only with the help of seven segment decoder

circuit. Here we use ic 7447 as a seven segment decoder circuit. IC 7447

receive the BCD signal from the 8870 and convert this signal in the numeric

display.

Now when we press the numeric code from the transmitter end then

transmitter transmit the signal in the form of light. This light is receive at the

other end in the form of the laser light. This laser light is decode into signal

and this signal is amplified and converted in to numeric form with the the

help of decoder circuit. the light

CONDENSER MIKE

A microphone is a device, which converts the air pressure variation

produced by a voice or musical instruments in to an electrical variation of

the same frequency and corresponding amplitude. Its primary purpose is to

convert sound energy into electrical energy. It is based on a basic principle

to work in the sequence air-vibration, mechanical vibration and electrical

vibration.

The conversation of air vibration in to mechanical vibration is effected

mostly by means of a diaphragm, which work in much same way as the

eardrum in the human ear. In condenser microphone the diaphragm from one

plate of an air capacitor. Battery charges the capacitor to a certain value. The

resistance R is rather large when diaphragm vibrates as a result of sound

wave acting on it. The distance between the plates of the capacitor change

therefore the capacitor value also change and it causes a small AC to flow in

the circuit. The AC voltage an alternating voltage develops.

SPEAKER

The speaker simply changes electric energy into sound. The speaker is a

transducer. One in a family of devices which converts energy from one form

into another.

The speaker in greatest use today is the permanent magnet (pm) dynamic

speaker. The electrostatic, speaker may be found as part of a speaker system

in hi-fi installations. Electromagnetic dynamic speakers are no longer used,

although they were very popular early in the development of audio systems.

Dynamic speakers are similar in operation. They differ in method used to

obtain the stationary or static magnet field. The mechanical construction of a

pm speaker.

A permanent magnet concentrates a magnetic field at the pole pieces of

highly permeable housing. The pole pieces are very close together to obtain

an intense magnetic field. A voice coil cemented to the speaker cone is

freely suspended between the magnetic poles. A flexible membrane called

the spider is attached to the voice-coil form and cemented to the speaker

frame. The spider centers the voice coil forms between the speaker poles and

keeps it from rubbing against them. The flared end of the cone is flexibly

attached to the speaker frame.

The permanent magnet of a pm speaker is made of a mixture of aluminum,

nickel and cobalt and is called an alnico magnet.

COMPONENT USED.

TRANSMITTER CIRCUIT:

IC 741. & IC BASE

CONDENSER MIKE, L.E.D

10 K (5), 100 K OHM VARIABLE RESISTOR( PRESET)

P.C.B. ( PRINTED CIRCUIT BOIARD)GENERAL

9 VOLT BATTERY AND BATTERY SNAPPER

CAPACITOR 1000MFD (1) , .04 MFD (1)

L.E.D.

OPTICAL FIBRE.

COMPONENTS RECEIVER:

IC 741

PHOTODODE

10 K OHM (5)

1 K OHM

100 K OHM ( VARIABLE RESISTOR) PRESET

100 MFD, 1000MFD, .04 MFD

SPEAKER

P.C.B ( PRINTED CIRCUITBOARD)

OPTICAL FIBRE

COMMUNICATION

CAPACITOR.

Capacitance is the property of opposition to a change in voltage. Capacitance has the same reaction to voltage as the inductance has to the current. That is the voltage across circuit increases. Capacitor will resist the change and if the voltage applied to a circuit is decreased and try to maintain the original voltage.

The property of the capacitor is to store charge and release. The storing capacity of capacitor depends upon the value of capacitor as defined in micro farad.

A basic capacitor consist of two conducting metalplates separated by a layer of air or other insulating material. The insulating layer is called dielectric layer. In practice the dielectric layer are often staked and even rotted into compact form. The capacitor are as classified by the name of dielectric used in particular.

1. Paper capacitor.2. Mica capacitor3. Ceramic capacitor.4. Electrolytic capacitor.

All electrolytic capacitors have the values are above 1 micro farad. All

electrolytic capacitor having two legs , One is positive and second is

negative, The bigger leg is positive and smaller leg is negative.

LIGHT EMITTING DIODE

It is diode which emits visible light when it is energized. In all

semiconductor PN junction diodes some of the energy is given off as heat

and some in the form of photon. In silicon and germanium types the greater

the percentage is given up in the form of emitted light, the heat generated

becomes insignificant. In other words, materials such as gallium arsenic

phosphide ( GaAsP) or gallium phosphide ( Gap) , the numbers of photon of

light energy emitted is sufficient to create visible light source. The process

of giving off light by applying an electric source of energy is called

electroluminesce .Thus L.E.D. is a PN junction having a forward bias and

characteristics similar to diodes. L.E.D. operate at voltage level of 1.7 volt to

3 volt by epoxy lens. The two electrodes are metal frame and the leads

coming out of the enclosure from the outlet and inlet are for the voltage. All

the L.E.D. are highly monochromatic. Three colour’s are commonly

available : Red, Green, and yellow. Blue LED’S also exists, but are

expensive. LED’S are widely used in display’s and as indicators. the shape

of LED varies considerably, but the most common type is cylindrical, with a

hemispherical end. The longer of the two leads is the anode, which must be

connected to the positive voltage

Digital transmission.

In this digital transmission we transmit the signal in digital

form. We transmit this data on the laser or small L.ED.. When we point the

laser beam on the receiver point then laser light develop a small

voltage in the photodiode and due to this laser light photodiode

convert this light into small voltage and further converted into

numeric display.. In the case of optical fibre we connect the light from

transmitter to one end of optical fibre and other end of the optical fibre is

connected to the photodiode.

In transmitter section we use 9 switches for the nine decimal

number’s and the output circuit we use one seven segment display

for the numeric display.

In transmitter section we use one DTMF signal generator for

generating a signal in the form of PWM pulse width modulation.

for this purpose we use ic UM 91513 as a transmitter. This UM

91513 is a commonly dtmf signal generator IC. All the nine

switches are connected to the input of this IC . All the

switches are connected together as a matrix network. All the

switches are divided in four row and three column. We indicate the

row as a R-1,R-2, R-3, R-4 and column as a C-1, C-2, C-3 . When

we press the switch no 1 then Pin no 15 and pin no 12 is activate

because pin no 15 is connected to the R-1 and pin no 12 is

connected to the C-1. Pin no 6 of this ic is connected to the

positive supply. This ic is very sensitive to voltage and require

only 3.3 voltage. for this purpose we use one zener diode

regulated power supply with this project. Resistance 150 ohm

limit the current and 3.3 volt zener regulate the input supply

voltage. One crystal is connected to pin no 3.579545 MHz is

connected to the pin no 3 and 4. this frequency is a carrier

frequency of this input pins. Output signal is available on the

pin no 7 of this ic. This output signal is directly connected to

the operational amplifier circuit. In this operational amplifier

we use ic 741 as a amplifier circuit. Input signal from the pin

no 7 of this ic is connected to the pin no 2 of the ic 741. Pin

no 3 act as a comparator. Pin no 6 is output pin. Pin no 7 is

connected to the positive supply and pin no 4 is connected to the

negative supply. One resistor is connected between pin no 6 and

pin no 2 to give a positive feedback. Output from the operational

amplifier is further amplified by the two transistor. We use two

transistor’s are here one is NPN and second is PNP. collector of

₃the npn is connected to the positive supply and collector of the

pnp is connected to the negative supply. Output is available from

the emitter of the both transistor. Output from the transistor is

further connected to the laser beam. Here we use Ga-as laser. In this laser

beam there is one semiconductor laser diode. Working voltage of this diode

is approx. 3.6 volt. This diode is very sensitive and on high voltage it is

immediately burnt out. Output from the amplifier is further again converted

into regu₃lated 3.6 voltage with the help of one 3.6 volt zener diode. Now

when we press any switch from the keyboard then ic generate a frequency

and this frequency is amplified by the operational amplifier and this signal is

further transmit by the laser beam in the form of the light.

In receiver circuit We use one photodiode. Photodiode is very senstive to

light . When light focus on the photodiode then photodiode sense the light

and convert it into a very small voltage. This small signal is amplified by the

operational amplifier and further connected to the DTMF decoder circuit.

DTMF decoder circuit receive signal from the operational amplifier and

convert this signal into a BCD signal.

For the DTMF decoder circuit we use IV 8870/9170. This a 16 pin IC. Pin

no 10 and 18 is connected to the positive supply. One crystal is connected to

the pin no 7 and 8 to demodulate the frequency. Signal from the operational

amplifier is applied to the pin no 2 and 3 of this ic. This ic Receive the signal

and demodulate the frequency and this frequency is available on the pin no

11,12,13,14 in the form of BCD signal. If we use this BCD signal in further

then we can control many electrical appliances through this circuit. But here

we display the numeric number only with the help of seven segment decoder

circuit. Here we use ic 7447 as a seven segment decoder circuit. IC 7447

receive the BCD signal from the 8870 and convert this signal in the numeric

display.

Now when we press the numeric code from the transmitter end then

transmitter transmit the signal in the form of light. This light is receive at the

other end in the form of the laser light. This laser light is decode into signal

and this signal is amplified and converted in to numeric form with the the

help of decoder circuit. the light

SOLDERING KIT

1. Soldering Iron : As soldering is a process of joining together two

metallic parts, the instrument which is used for doing this job is known

as soldering Iron. Thus it is meat for melting the solder and to set-up the

metal parts being joined. Soldering Iron are rated according to their

wattage which varies from 10 – 200 watts.

2. Solder : The raw material used for soldering is

solder. It is composition of lead & in the good quality solder (a type of

flexible naked wire is 60% Tin Led which will melt between 180

degree to 200 degree C temperature.

3. Flux for Soldering Paste : When the points to soldered is heated, as

oxide film forms. This must be removed at once so that solder may get

to the surface of the metal parts. This is a done by applying chemical

substances called Flux, which boils under the heat of the iron remove

the oxide formation, and enable the metal to receive the solder.

4. Blade or Knife : To clean the surface &^ leads of components to be

soldered is done by this common instrument.

5. Sand Paper : The oxide formation may attack at the tip of you

soldering iron & create the problem. To prevent this, clean to tip with

the help of sand paper time or you may use blade for doing this job.

Apart from all these tolls discussed above, the working bench for soldering

also includes disordering pump. With wire (used for disordering purpose),

file etc.