A Full Wave Rectifier Final

8/13/2019 A Full Wave Rectifier Final

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CERTIFICATE

This is to certify that Jasdeep Bajaj of XII (Non

Medical) of A.V.I. Public School, Sirsa has performed

the project work as per the syllabus of Central Board

of School Education Delhi and tried to give

satisfaction account in this file.

Signature .

(Internal Examiner)


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ACKNOWLEDGEMENT

During the preparation of this project I have been

guided and assisted by several people especially my

Physics Teacher, who influenced my style and way of

presenting this project and I am also thankful to my

friends for their sincere help. I sincerely feel that

this method of presenting the project will help my

examiner who is going to make the thorough study of

this matter and will point out of my mistakes.

Thanking You.

Jasdeep Bajaj

Roll No.........


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FOREWORD

This project is submitted in partial fulfilment of the

requirement laid down for course prescribed of

Physics project by the Central Board of Secondary

Education New Delhi, for all India Senior Certificate.Under the guidance of Mr. Mandeep

INTERNAL EXAMINER.

EXTERNAL EXAMINER.


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PREFACE:-

Name of the Project : Full Wave Rectifier

Project Guide : Mr. Mandeep

Mode of Project : Group

Roll No. :

Name of School : A.V.I. Public School,

Sirsa


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INTRODUCTION

A full wave rectifier is a device which is used to rectify

all the alternating current components in an

alternating supply and make it purely a direct current.

The two alternating halves of an alternation current are

rectified in a full wave rectifier which is an advantage over

a half wave rectifier. Most of electronic devices cannot

withstand very high voltage or alternating current due to itsintense high power. The use of batteries in all

devices is not practical as their replacement and durability is

a huge problem as the device has to be dismantled each time for

such a replacement. So these rectifiers are used in most of the

electronic devices like TVs, Radios, Chargers and Lightings etc.

There are several stages in a rectifier. Based on theirrectification they are classified into two:-

The single staged & multi staged. In the multi staged

rectifiers, more than two diodes are used and these are

used in the above-mentioned devices. The singled staged

rectifier has only 2 diodes, the one we are to discuss in this

project. The multi diode rectifier has only 2 diodes, the

one we are to discuss in this project. The multidiode rectifiers have efficiency ~ 94.6% while that of the

single is only 81.2%.


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THEORY INVOLVED:-

The input transformer steps down the A.C mains from 220Vto 9V between the centre tap and either of the

two en ds of the se conda ry winding. The transformer has

a capability of delivering a current

Of 500mA.

T h e 9 V A . C a p p e a r i n g a c r o s s t h e s e c o n d a r y i s t h e R

MS value of the waveform and peak value would be .4826volts=x

The diodes rectify the A.C waveform appearing across the

secondary with the help of alternate forward and reverse

biasing. The capacitor further filters 99% of the resident

components and this is left to pass through the resistance and

emerges out as +ve and ve. The bulb connected verifies the

output as it works on Direct Current and if used on an

Alternating Current, the fluctuation will burn out the bulb.

MATERIALS REQUIRED:-

Connecting wires, a plug, single lead wire - 2m, c a r db o a r d , a t r a n s f o r m e r , a f i l t e r , a r e s i s t o r ( 1 K )

, P - N j u n c t i o n d i o d e s , Insulation tape


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Details of the materials used:-

Connecting Wires and a Plug. A normal insulated copper wire able to withstand 220-250V is

required.

Single Lead wire-Thin wire with one single strand ofcopper well insulated and able to conduct a current of 1

ampere or a D.C current efficiently.

L.E.D It is called light emitting Diode (L.E.D). It is used totest the output voltage whether direct or not. It glows on as

we get a rectified direct current as an output. S t e p D o w n T r a n s f o r m e r -

A 9 - 0 - 9 t r a n s f o r m e r Tr ans fo rmer is a d evi ce

used to change the voltage of an alternating

current. The transformer which converts low voltage to

high voltage is called a step up transformer whereas the one

which converts high voltage to low voltage

i s c a l l e d a s t e p d o w n t r a n s f o r m e r .

I t c o n s i s t s o f laminated core consisting of two coils, aprimary & a secondary coil. In a step up the number of turns

in the secondary is greater that of the primary and the

reverse in a step down transformer. Here we use a step

down transformer which steps down 220V to 9V between the

secondary terminals and the centre tap.

Filter- It is used to filter the ripples, which is present in theoutput of the diode to an extent. Here we have used

1000MFD25V filter.

A Resistor- A resistor is electronic components whoseresistance value tells us about the opposition it offers to

the flow of electric current. Resistance is measured in ohms

().We determine the value of a resistor using the colour

coding on the rings of the resistor.


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P-N junction Diode:-When one side of asemiconductor crystal (Germanium or si l icon) is

doped with acceptor impurity atoms and the other

s i d e w i t h d o n o r i m p u r i t y a t o m s a P - Nj u n c t i o n i s f o r m e d . I t i s a l s o c a l l e d

S e miconductor or crystal diode. When diffusion of the two

regionsoccur a resultant potentialbarrier is created b

etween the two sides due to migration of electrons and

holes. When the diode is connected with P side to positive

terminal of a battery & N side to ve terminal it is said to be

forward biased & reverse biased when reversed. In forward

biasing the applied positive potential repels the holesand turns a current is made to flow overcoming the

internal potential Barrier. While in reverse biasing the ve

electrons 1stattract the holes and widen the Barrier and then

only the repulsion between

inner elect rons occur and c urren t f lows. So th eoret i

cal ly no cu rren t flows through due to the widening of

the Potential barrier but practically a very small current does

flows through.


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CIRCUIT DIAGRAM:-

Connection details:-

Connections are done as in the circuit. The A.C. supply is

given to bot h the i np ut w i r es of the tra nsfo rmer

and the two ends of the secondary coil is given to the

P side of the two diodes and the N side of the diodes are

twined and then connected to the o n e e n d o f t h ecapacitor and the other end to the centre tap lead and to the

resistor. Further, the other end of Filter with the

d i o d e c o n n e c t i o n i s connected to the other end of the

resistor. Connect 2 leads on both the ends of the resistor

to measure the output and this is connected to the +ve & -ve

terminals of the bulb.


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WORKING:-

First when the A.C. is supplied to the transformer, it

steps down the 220V main supply to 9 volts. It has a capability of

delivering a

Current Of 500mA. The 9 volts A.C. appearing across the

secondary is the RMS value and the peak value is 26 or 8.4

volts.

During the 1st half cycle of the A.C. input Diode D1 is forward

biased and a current flows in the circuit in the direction

S1D1ABEOS1. During this time diode D2 is reverse biased.So it does not conduct any electric current. During the next half

cycle the diode D2 is forward and D1 is reversed. Hence D2

conducts current in the direction S2D2ABEOS2and D1 does not

conduct any current. In subsequent half cycles of the A.C current

the above processes are repeated. In both the half cycles, it is clear

that current flows through the resistor in only one direction ABE.

Even though the voltage across RL is unidirectional it will still

contain a few A.C components. This is fi ltered and madesmoo th using a capacitor filter, which filters 99% of the A.C

current. A resistor is then used to adjust the output

voltage. We can then test the o/p Voltage using a multi-

meter.

Efficiency of Rectification -= D.C power output. Total A.C input

power For a half wave rectifier ~ 0.406 = 40.6 %For a full wave

rectifier, the one used here is ~ 0.812 = 81.2 %By the use of more

number of diodes the efficiency can be increase to a maximum of

94.6%. Here we only use 2 diodes. The use of multiple capacitors

also nearly filters all A.C components from the supply and

resistance is adjusted for the required output. As this

is a simple circuit, only one capacitor and a resistance is

being used. But there wil l be s lig ht fac tor of A.C . c urrent

still left in the output but it is negligible.


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WAVEFORMS:-

RESULT: - A full Wave rectifier is constructed & a

rectified DC voltage is obtained as an output.

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A Full Wave Rectifier Final