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SUBMITTED T0:
SUBMITTED BY:
Mrs.PARUL
NISHANT CHATURVEDI
(PGT ,COMMERSE)
XI- (COMMERSE)
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ZENER
DIODE AS
A VOLTAGE
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REGULATOR
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This to certify that student AASTHA
GUPTA of class XII- (SCIENCE) of
PARVATI RADHAKISHEN FOMRASCHOOL had completed his
investigatory project on ZENER
DIODE AS A VOLTAGE REGULATOR
under my guidance and to my
satisfaction .
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________________
_________________
TEACHERS SIGNATURE EXAMINERSSIGNATURE
First of all, I would like to thank God
who always helped at every step of
my project.
I would sincerely like to thank
Mr.ARUN PANDAYA who has been
always there to help me in carrying
out this project, acting as the
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guiding spirit behind the compiling
of this project.
I would like to offer my sincerethanks to my Principal Sir, Family,
my friends and all the people who
have helped me in completing my
project.
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AIM
INTRODUCTION THEORY
COMPONENTS USED
WORKING
BIBLIOGRAPHY
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1. BASIC ELECTRONIC CIRCUITS
2. BASIC ELECTRINICS: D. C. KULSHRESHTHA.
1. ELECTRONIC COMPONENTS MANUAL: PARSAI
2. A. B. C. OF PHYSICS: XII
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The purpose of this project is to show how an
NPN transistor works as a current amplifier
by controlling a large current (Collector
Current) with a small current (Base Current)
Build the circuit shown in the circuit diagram,
press the push-button then observe &
compare the brightness of the base LED
(LED1) and the Collector LED (LED2).
Transistors are made from semiconducting
materials such as Silicon or Germanium.
Depending on how the transistor is
constructed it becomes an NPN of PNP type.
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When the collector of an NPN transistor is positive.
The Emitter is negative and the base is slightly
positive the transistor is correctly biased
(polarized) and there are two currents flowing
through the Collector Current (Ic) which is a large
current and the base current (Ib), which is a small
current as shown in fig. The interesting thing
about transistors is that the base current, which is
a small current, controls the Collector Current. The
larger the base current, the greater the Collector
Current and vice versa.
This important process of having a small current
controlling a large current is known as
amplification. Performing the experiment .you
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have found that LED2 (Collector LED) was brighter
than LEDI (Base LED). This means that the
Collector Current is larger than the base current.
In this experiments you also found out that if there
is no Base Current (Push- button open) there is no
Collector Current if there is a base Current (key is
pressed) there is a Collector Current. Thus you can
conclude that the transistor is working as an
amplifier.
2 RESISTANCES: 22 OHM
22 OHM
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1TRANSISTOR: NPN 547
2 LED: RED
RED
BATTERY: 3V
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Under the forward bias the (negative) electrons in
the emitter (n-region) move towards the base,
while the (positive) holes in the base (p-region)
move towards the emitter. Since the base is very
thin, most of the electrons entering it pass on to
the collector, while a very few of them combine
with the holes present in the base. As soon as an
electron combines with a hole, an electron leaves
the negative pole of the battery VEB and enters the
emitter through the terminal E. At the same
instant, a covalent bond breaks in the base; the
electron produced enters the positive pole of the
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battery VEB, and the hole produced in the base
compensates for the hole lost by combination.
Thus, a current flows in the base-emitter circuit.
The electrons entering the collector move under its
reverse-bias (which aids them) and reach the
terminal C. As soon as an electron leaving C enters
the positive pole of the battery VCB ,an electron
leaves the negative poles of the battery VEB and
enters the emitter. Thus , a current flows in the
collector- emitter circuit .
It is obvious that the electrons are the charge carriers
within the n-p-n transistor as well as in the external circuit.
It is obvious that the electrons are the charge carriers
within the n-p-n transistor as well as in the external circuit.
Ie =Ib +Ic
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BIBLIOGRAPHY
1. BASIC ELECTRONIC CIRCUITS
2. BASIC ELECTRINICS: D. C. KULSHRESHTHA.
3. ELECTRONIC COMPONENTS MANUAL: PARSAI
4. A. B. C. OF PHYSICS: XII
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