regulated power supply made by--rajat aggarwal
Post on 26-Mar-2015
1.609 Views
Preview:
TRANSCRIPT
MINOR PROJECT WORKREPORT
ONREGULATED POWER SUPPLY
Submitted to State Board of Technical Education
For the partial fulfillment of the requirement for the award
Of diploma of Electronics and Communication Engineering
for the
SESSION: 2008 TO 2011
Submitted by: - Submitted to:-
Rajat Aggarwal Mr. Chanan Pawar
0809810040 Sr. Lecturer
Electronics & Comm. Poonam Mehta Engineering
0809810033
Manisha
0809810023
ACKNOWLEDGEMENT
We are deeply indebted to “ Mr. Chanan Pawar Sr. Lecturer in Department of Electronics & Communication Engg. at Ambition Institute Of Polytechnic , Moriwala (Sirsa)”. For his inspiring and encouraging guidance without which this project work could not have been completed inspite of his busy schedule. He always had time to attend the problem faced by us in our project work. We will always remember his quick analysis, comprehensive solution and critical reviews, he has been given through out the project work.Cordial and earnest thanks to staff of Ambition Institute of Polytechnic, Moriwala (Sirsa) for his valuable suggestion and help remembered in conducting the project work.But at last, but not least we express over indebtedness to our parents and all other family members for their patience and help extended in this end over.
Rajat Aggarwal0809810040
Poonam Mehta0809810033
Manisha0809810023
Ambition Institute of PolytechnicMoriwala (Sirsa)
CONTENTS CHAPTER-1 INTRODUCTION
o Introduction.
o Theoretical background
o Aim to design this project
o Application
o Advantages
CHAPTER-2 PROJECT DESCRIPTIONo block diagram
o block description
o circuit diagram
o circuit description
o component used
o working principle and operation
CHAPTER-3 FABRICATION PROCESSo fabrication techniques
o various tools and equipment
o soldering
o tips and tricks
o precautions
CHAPTER-4 TESTING CHAPTER 5 RESULT AND CONCLUSION Reference
Chapter:-1
INTRODUCTION
INTRODUCTIONRegulated power supply
In general, electronic circuit using transistors require a source
of DC power for example in tube amplifiers, DC voltage is
needed for plate, screen grid and control grid. Similarly the
emitter and collector bias in a transistor must also be direct
current. Batteries are rarely used for this purpose as they are
costly. In practice DC power for electronic circuit is most
conveniently obtained from commercial AC lines by using
rectifier-filter system, called a DC power supply. The rectifier-
filter combination constitutes an ordinary DC power supply.
The DC voltage from an ordinary power supply remains
constant. So long as AC mains voltage or load is unaltered.
However, in many electronic applications, it is desired that DC
voltage should remain constant irrespective of change in AC
mains or load under such situations, voltage regulating devices
are used with ordinary power supply. This constitutes
regulated DC power supply and keeps the DC voltage at fairly
constant value.
CERTIFICATECertify that the project entitled “variable regulated power
supply” submitted by Rajat Aggarwal 0809810040, Poonam
Mehta 0809810033 and Manisha 0809810023 in partial
fulfillment of the requirement for the award of “Diploma in
Electronics & Communication Engg. by the state board of
Technical Education Punjab Panchkula” is a record student
own project work carried out under my supervision.
Er. Chanan Singh Pawar
Electronics & Comm. Engg.
Ambition Institute of Poly.
Moriwala (Sirsa)
Ambition Institute of PolytechnicMoriwala (Sirsa)
Chapter:-2
PROJECT
DESCRIPTION
BLOCK DESCRIPTIONTransformer: - The low voltage AC output is suitable for lamps,
heaters and special AC motors. It is not suitable for electronic circuits
unless they include a rectifier and a smoothing capacitor.
Transformer + Rectifier: - The varying DC output is suitable for
lamps, heaters and standard motors. It is not suitable for electronic
circuits unless they include a smoothing capacitor.
Transformer + Rectifier + Smoothing: - The smooth DC output
has a small ripple. It is suitable for most electronic circuits.
Transformer + Rectifier + Smoothing + Regulator: - The
regulated DC output is very smooth with no ripple. It is suitable for all
electronic circuits.
CIRCUIT DISCRIPTIONStep Down Transformer :- Transformers convert AC electricity
from one voltage to another with little loss of power.
Transformers work only with AC and this is one of the reasons
why mains electricity is AC.
Step-up transformers increase voltage, step-down transformers
reduce voltage. Most power supplies use a step-down
transformer to reduce the dangerously high mains voltage
(230v) to safer low voltage.
Transformers and their symbol
The input coil is called the primary and the output coil is called
the secondary. There is no electrical connection between the
two coils, instead they are linked by an alternating magnetic
field
created in the soft-iron core of the transformer. The two lines
in the middle of the circuit symbol represent the core.
Transformers waste very little power so the power out is
(almost) equal to the power in. Note that as voltage is stepped
down current is stepped up.
The ratio of the number of turns on each coil, called the turn’s
ratio, determines the ratio of the voltages. A step-down
transformer has a large number of turns on its primary (input)
coil
which is connected to the high voltage mains supply, and a
small number of turns on its secondary (output) coil to give a
low output voltage.
turns ratio = Vp
= Np
and power out = power in
Vs Ns Vs × Is = Vp × Ip
Vp = primary (input) voltage
Np = number of turns on
primary coil
Ip = primary (input) current
Vs = secondary (output)
voltage
Ns = number of turns on
secondary coil
Is = secondary (output) current
Rectifier: - There are several ways of connecting diodes to
make a rectifier to convert AC to DC. The bridge rectifier is
the most important and it produces full-wave varying DC. A
full-wave rectifier can also be made from just two diodes if a
centre-tap transformer is used, but this method is rarely used
now that diodes are cheaper. A single diode can be used as a
rectifier but it only uses the positive (+) parts of the AC wave
to produce half-wave varying DC.
Bridge Rectifier: - A bridge rectifier can be made using four
individual diodes, but it is also available in special packages
containing the four diodes required. It is called a full-wave
rectifier because it uses all the AC wave (both positive and
negative sections). 1.4V is used up in the bridge rectifier
because each diode uses 0.7V when conducting and there are
always two diodes conducting, as shown in the diagram below.
When AC supply is switched on. During positive half cycle
terminal A is positive and B is negative. This makes diode D1
& D3 forward biases & diode D2 & D4 reverse biases and we
get positive cycle.
During –ve half wave cycle, the A becomes –ve and B
becomes +ve. Due to this D2 & D4 come under forward bias
and diode D1
& D3 are reverse bias. Therefore, diodes D2 & D4 conduct
while diode D1 & D3 don’t. the shape of wave is shown in
figure.
Bridge Rectifier
Output: full-wave varying DC
Hence, we can say that the bridge wave rectifier give the
pulsating DC voltage which are not suitable for electronics
circuit.
Smoothing (Filter): - Smoothing is performed by a large value
electrolytic capacitor connected across the DC supply to act as
a reservoir, supplying current to the output when the varying
DC voltage from the rectifier is falling. The diagram shows the
unsmoothed varying DC (dotted line) and the smoothed DC
(solid line). The capacitor charges quickly near the peak of the
varying DC, and then discharges as it supplies current to the
output.
Note: - Note that smoothing significantly increases the average
DC voltage to almost the peak value (1.4 × RMS value).
Smoothing is not perfect due to the capacitor voltage falling a
little as it discharges, giving a small ripple voltage. For many
circuits a ripple which is 10% of the supply voltage is
satisfactory and the equation below gives the required value
for the smoothing capacitor. A larger capacitor will give less
ripple. The capacitor value must be doubled when smoothing
half-wave DC.
So, in this we concluded that the pulsating DC voltage is
applied to the smoothing capacitor. This smoothing capacitor
reduces the pulsations in the rectifier DC output voltage.
The smooth DC output has a small ripple. It is suitable for
most electronics circuits.
capacitor
Adjustable regulator: - Voltage regulator ICs are available
with fixed or variable output voltages. The regulated DC
output is very smooth with no ripple. It is suitable for all
electronic circuits.
When voltage regulating device is added to this ordinary
power supply, it turns in to a regulated power supply.
Voltage regulator
In this we used adjustable voltage regulator. The adjustable
voltage regulator can be adjusted to provide any DC output
voltage that is within its two specified limits. The most popular
three terminal IC adjustable voltage regulator is the KA317. It
has an input terminal, output terminal and an adjustment
terminal.
An external voltage divider is used to change the DC output
voltage of the regulator. By changing external voltage divider
means variable resistance, a wide range of output voltage can
be obtained. Most regulators include some automatic
protection from excessive current (overload protection) and
overheating
(Thermal protection).
HOW TO CONSTRUCTFirst of all read the given manual thoroughly and study the
circuit given in the figure. Also have a look at PCB and
components supplied along with the kit. Each component has
to be soldered in its position on PCB.
Identification of resistors is done by color-coding. The color
band on each resistor corresponds to its exact value.
There are different methods in which are defined on
capacitors. But usually values are specified numerically on
them. Refer “Basic Electronics” section of the manual for
details of resistor and capacitor identification methods.
Can you make out the whole working of circuit and are you
able to identify each component separately as to where each
of them has to be placed?
If yes, only then proceed further to actually mounting and
soldering the parts refer to “Soldering Instructions” section.
Not IC’s but their sockets are to be soldered on PCB. This is to
make mounting and dismounting of IC’s easy while
troubleshooting.
Start from left most corner of PCB and solder the components
one by one on their correct position of PCB.
Before soldering any component see that you have placed it at
its right position and with correct polarity. Give due attention
to diodes and electrolytic capacitors, as they are polarity
dependent.
Do the soldering of other components in the same way while
keeping in mind that components with long and sensitive
leads like capacitors and transistors are soldered last.
CHAPTER:-3
FABRICATING
PROCESS
FABRICATING
TECHNIQUESThe fabricating techniques used in this project can be broadly
classified into:
o Mechanical Fabricating, consisting of mechanical design.
o Electrical Fabricating, consisting of electrical design i.e.
making PCB, soldering, is making connection correctly etc.
VARIOUS TOOLS & EQUIPMENTS
NEEDED FOR FEBRICATION
Soldering wire De-soldering iron
Flux
Wire cutter Multimeter
SOLDERINGSoldering is a process in which two or more metal items are joined
together by melting and flowing a filler metal into the joint, the filler
metal into the joint, the filler metal having a relative low melting point.
Soft soldering is characterized by the melting point of the filler metal,
which is below 4000 C (7520F). The filler metal used in the process is
called solder.
Soldering is distinguished brazing by use of a lower melting-temperature
filler metal; it is distinguished from welding by the base metals not being
melted during the joining process. In a soldering process, heat is applied
to the parts to be joint by capillary action and to bond to the materials to
be joined by wetting action. After the metal cools, the resulting joints are
not as strong as the base metal, but have adequate strength , electrical
conductivity and water tightness for many uses . soldiering is an ancient
technique mentioned in Bible and there is evidence that it was employed
upto 5000 years ago in Mesopotamia.
TIPS & TRICKSSoldiering is something that needs to be practiced. These tips should help
you began successful so you can stop practicing and get down to some
serious building.
1. Use heatsinks. Heatsinks are must for the leads of sensitive
components such as on
2. Keep the iron tip clean. A clean iron tip means better heat conduction
and a better joint. Use a wet sponge to clean the tip between joints.
3. Double check points. It is good idea to check all the soldiers joints
with an Ohm meter after they are cooled. If the joint measures any
more than a few tenths of an ohm, then it may be a good idea to
resolder it.
4. Use the proper iron. Remember that bigger joints will take longer to
heat up with an 30W iron than with a 150w iron. While 30W is good
for printed circuit boards and the like, higher wattages are great when
soldiering to a heavy metal chases.
5. Solder small parts first. Solder resistors , jumper leads, diodes and
any other small parts before you solder larger parts like capacitors
and transistors. This makes assembly much easier.
PRECAUTIONS
1. Mount the components at the appropriate places before
soldering; Follow the circuit description and components details,
leads identification etc. Do not start soldering before making it
confirm that all components are mounted at right place.
2. Do not use a spread solder on board, it may cause short circuit.
3. Do not sit under the fan while soldering.
4. Position the board so that gravity tends to keep the solder where
you want it.
5. Do not over heat the components at the board. Excess heat may
damage the component or board.
6. The board should not vibrate while soldering otherwise you
have a dry or cold joint.
7. Do not put the kit under or over voltage source. Be sure about
the voltage either dc or ac while operating the gadget.
CHAPTER:-4
TESTING
BLOCK DIAGRAM
CIRCUIT DIAGRAM
Fig: - Regulated Power Supply
TESTINGThe testing step comes after the fabrications processes or we can say this
is the final step of our project. In this process we have done testing of our
project by hardware section.
Hardware section
In the hardware section, first of all we have tested the soldiering section of
power supply, after that in this we have checked that we are receiving the
output required or not, i.e. 5V from the power supply section. After
founding that the power supply section is working as per our requirement
we moved to another section for testing. We tested the connection of
capacitors, resistors, transistors. Finally we had gone through the whole
circuit and check if there are no loosened wires, breaking of tracks etc. the
tools required for testing the hardware section was:
Soldering rod, flux and lead
Twisser and stipper
Digital multimeter
Desoldering gun
COMPONENT USED
Step down transformer :- The step down transformer can convert
high voltageAC into low voltage AC. By step down transformer
we can take different values of voltage at output. In this project
we can use 12-0-12 step down transformer. In this transformer
we give high AC voltage by two red wires & take low AC voltage
output by eight wires. At eight wires we can obtain various
outputs.
Bridge wave rectifier : - In the full wave rectifier we can use four
diodes. These rectifiers can convert AC voltage into DC voltage.
In this circuit we use four diodes of value 4007 to make a full
wave rectifier. These four diodes give full wave at output. One
diode takes 0.7v to operate.We can use two diode to take full
wave at output but for this we require a center tap transformer,
this is not generally use because these are chipper. At output we
obtain pulsating DC volt.:-
Capacitor :- Capacitor are use for either to store the charge or
for smoothing purpose. But in this circuit we use capacitor for
smoothing purpose. It give the DC voltage but this DC voltage
contain some ripple.
Adjustable regulator: - In this circuit we use adjustable regulator
KA317. This regulator is use to take DC voltage. At this DC
voltage no ripples are present.
The terminal 1st is input terminal through which we take the DC
voltage which is provided by the capacitor. 2nd terminal is earthing
terminal & 3rd terminal is output terminal through which we take
the output.
top related