tapendra transistor as a switch

8/10/2019 Tapendra Transistor as a Switch

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ANAN

INVESTIGATORYINVESTIGATORY

PROJECTPROJECT

ININ

PHYSICSPHYSICS


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CERTIFICATECERTIFICATE

THIS IS TO CERTIFY THAT INVESTIGATORY

PROJECT ENTITLED

C. E. AMPLIFIERC. E. AMPLIFIER

IS AN ORIGINAL WORK DONE BY

AANKITNKITVVERMAERMA

DURING

2005-02005-0 UNDER MY SUPERVISION ! GUIDANCE

M". E#$%& T. J. M"'. S("%)( A&%*M". E#$%& T. J. M"'. S("%)( A&%*

P*(+,

D(),


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DECLARATION

I here by declare that the project entitled

C.E. AMPLIFIERC.E. AMPLIFIER

is an original work done by me during the year 2005-02005-0

under the guidance and supervision of

M". E#$%&.T.C ( M"'. S("%)( A&%*M". E#$%&.T.C ( M"'. S("%)( A&%*.

S%&()/", 1 ), /%#,.. AANKITNKITVVERMAERMA

3. 444444444.

2. 44444444.....


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ACKNOWLEGEMENTACKNOWLEGEMENT

I AANKITNKITVVERMAERMAof standard XII of Science Stream S STT..MMARYARY66SSIINTERNTERCCOLLEGEOLLEGEEETAWAHTAWAHis genuinely thankful to my

teacher MMRR. E. EDWINDWINT.CT.C ANDANDSSARITAARITAAANILNILfor their help and able

guidance which I received for the completion of this project.

C.E.AC.E.AMPLIFIERMPLIFIER

I am also thankful to the principal, my co-student and parents

who have always given me their support which was of immense help

towards the completion of this project.


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INTRORDUCTION7INTRORDUCTION7

he common emitter amplifier is the device which is

used to amplify voltage signal. his type of amplifier is saidto be common emitter amplifier as it has got common emitter

for both input as well as output signals. his type of

amplification is widely use in wide range in he field of

electronics.

AIM7AIM7

o construct and study the working of the common

emitter amplifier.

MATARIALS RE8UIRED7MATARIALS RE8UIRED7

!or the construction of ".#.$%&'I!I#( an n)p)n

transistor of value *.".+ is used .hree capacitor of value

./0!, /0! and /0! are re1uired. !our resistance of

value 2.3k4, .3k4, /.5k4 and /.5k4 are re1uired.


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CONSTRUCTION DIAGRAM7CONSTRUCTION DIAGRAM7

CIRCUIT DETAILS7CIRCUIT DETAILS7

/./. N7P7N TN7P7N TRANSISTORRANSISTOR77

$ transistor is a device used for amplifying the

signals. $ transistor can be produced by adding anotherjunction to the &)6) 7unction diode. *ased upon the junction

added to the &)6) 8iode the transistor are broadly divided

in to two types.


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i9 6)&)6 ransistor

ii9 &)6)& ransistor

he 6)&)6 ransistor is the produced by adding an 6)7unction to a &)6 7unction 8iode

he &)6)& ransistor is the produced by adding a &)

7unction to a &)6 7unction 8iode

6ormally , 6-&-6 ransistor are used as the common emitter

amplifier in the circuit in which either of two 6- type

semiconductor can act as emitter or collector respectively and&-type semiconductor act as base.

WORKING OF N-P-N TRANSISTORWORKING OF N-P-N TRANSISTOR

he working of 6-&-6 ransistor can be studied with the

help of the finger. he working of ransistor can be studied

by connecting the emitter base circuit as input in forward bias

that is by connecting positive terminal of battery with baseand negative terminal with emitter of the transistor.

DIAGRAM OF N-P-N TRANSISTOR

Ie n-p-n Ic

Ib

: :

I, 9 I:; I+


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$nd the output circuit ;*" "ircuit9 is reversed biased by

connection the positive terminal of the battery with collector

and negative terminal with base. he voltage of battery used

for the output circuit is less that the voltage of battery usedfor input circuit.

he forward bias of the emitter-

base circuit help the movement of electrons ;majority carrier9

in the emitter and ;majority carrier9 in the base towards the

junction between the emitter and the base. he depletion

layer of the emitter base junction is reduced on the other hand

the reverse. 9

of the incoming electrons combine with the hole . %ore over

the electrons are reaching towards the collection under the

electrostatic influence of the positive terminal of the collector

base battery.

he electron collected by the collector %oves

towards the positive terminal of the collector base battery.

he deficiency of the collector base battery. he deficiency of

these electrons is made up by the electrons released fro the

negative terminal of the current is carried by the electrons

both from the e=ternal as well as from the internal of the

terminal of the transistor.


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'et the current through emitter be Ie, through base be I*and

through collector be I"hen by ?irchoffs law

I, 9 I:;I+

CAPACITOR-

"apacitor is an electronic device which is used to store

electric charge. he capacitor can be spherical, cylindrical

capacitor and &arallel plate capacitor.

PRINCIPLE7

o understand the principle of capacitor consider an isolated

metal plate $. Suppose it is given positive charge till its

potential becomes minimum. he metal plate will not hold

any more charge over it. If charge is given to the metal plate

$ it will leak to surroundings. 6ow place another metallic

plate * while positive charge on its further face. he induced

negative charge on * is near to the metal plate $ then the

induced positive charge on *, therefore, on the whole

potential of the metal plate $ is lowered of the metallic plate.

$gain the some small amount of more charge has to be given.It indicates the capacitance of a conductor increase by a small

amount when conductor increase by a small amount when

another is placed near it. 6ow connect the metal plate * to

the earth. he induced positive charge on * will immediately


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/. Intrinsic semi conductor

5. #ntrinsic semi conductor

INTRINSIC SEMI CONDUCTORhe semi conductor which are insulator in pure state arecalled intrinsic semi ) conduction.

E

, ',?% +/+)"

8oping a pure semi conductor with pentavalent impurityatoms such as phosphorus, arsenic, yield 6-type semi

conductors. In 6-type electrons are majority charges carriers

and holes are minority charge carriers.

P-T=>, S,?%-C/+)"'8oping a pure semi-conductor with trivalent impurity atoms

such as *ismuth, aluminium, indium etc., yield &-type semi-conductors. Doles are majority charge carriers B free

electrons are minority charge carriers.

P-N-@/&+)%&


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Ehen a &-type semi-conductor is brought into a close contact

with 6 type semiconductor crystal the resulting arrangement

is called &-6 junction.

DEPLETION REGIONhe region in which free charge carriers are not available is

called a depletion regions.

here are 5 methods of biasing the &-6 junction.

( F"$("# :%('%&Ehen the positive terminal is connected to p-type semi-

conductor and negative terminal to the n-type semi-conductor

of the &-6 junction.

: R,',", :%('%&In reverse biasing the positive terminal of the battery is

connected to 6 side B negative terminal top side of the &-6

junction.

DIAGRAM OF C.E. A MPLIFIER/"

Input


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W"%& 1 C.E. A?>*%1%,"he emitter is common to both input B output circuits. he

emitter is forward based by using base-emitter battery #*!

and is in forward bias, the resistance of input circuit is low.he collector emitter circuit is reverse biased by using

collector emitter battery #"!. he low input voltage signal is

applied in base emitter circuit;input circuit9 and the amplified

output is obtained across the collector and emitter. he arrow

represents the pole current or the conventional current.

he emitter current, base current B collector are related

to each other by the e1uation

/e G /b :/c ; by kirchoffHs law9. $lso, corresponding to

collector current /c, the collection voltage will be,

FcG Fce) /c(" e1../

he variation in input signal voltage cause variation in

emitter current, which inturn provides charges in collector

voltage B appear as amplified output voltage. he input

voltage signal B obtained across emitter and collector are outof phase with each other in common emitter amplifies as

e=plained below.

Suppose that first half cycle of $.". input voltage is

positive, refreshing to figure, or base is connected to positive

pole #"! battery, it will make base more positive. hus

negative forward bias of emitter will increase. It will increase

the collector current which will increase potential drop acrossresistance and then according to e1uation ;/9, the collector

voltage means the collector will become less positive, i.e.

negative output signal will be obtained.

Similarly, we can prove that corresponding to negative

half cycle of $.". input positive half cycle will be obtained.


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5. !rom "onductance ;gm9C It is defined as the ratio

of change in collector current to the change in base

emitter voltage. ;JFi9

@m G JIcAJFiA

G JIcAJIbL JIbAJFI@m G K a.c L J(IS.I unit G M-/

$." Foltage @ain

It is defined as the ratio of output voltage to

the change in input voltage

$v G J FcAJFi

G J IcL (o AJ I2L(I G Ka.c L (oA(ii$v G Ka.c L (esistance gain

$." power @ainIt indefined as the ratio of change in output power

to change in input power

$." power gain G change in output powerAchange

in input power

G;J Ic5 LKI2

59L;(oA (i9

G K5a.cL ( gain

G Ka.cL;Ka.c L( gain9

$." power gain G Ka.c L $v

(eiation *etween N B K


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G Ic A I2

G Ic A Ie ) Ic;Ic GI29

8ividing both 6umerator and 8enominator by Ie

G IcAI# IeAIe-IcAIcON G IcAIeP

PRECAUTION-i9 he current voltage and however ratings of transistors

for its base, collector etc. must not e=ceed the

recommendation valves, otherwise the device would

be damaged.

ii9 $t the time of making soldered connection to the

leads of a transistor the lead is held between pliers

very tightly B soldering should be done in minimum

possible time. So that much of heat cannot pass

through lead B would have the transistors fromgetting damaged.

CONCLUSION-he conclusion drawn out of the project ".#

amplifier is that the current grain is ma=imum in the

type of amplifier. herefore, it is of great use inelectronics.


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BIBLIOGRAPHY

/. 'ali manual of physics - "omprehensive

5. %odern $*" of &hysics - $rya book depot

Q. "omprehensive &hysics - "omprehensive

&ublications

tapendra transistor as a switch

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