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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