parvati radhakishen

7/30/2019 Parvati Radhakishen

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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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