THE REPORT FILE ON FABRICATION OF REGULATED DC POWER SUPPLY OF +5 V AND +12 V .

1. 1
A PROJECT REPORT ON
THE FABRICATION OF REGULATED DC POWER SUPPLY
SUBMITTED TO
ELECTRICAL DEPARTMENT
BABARIYA INSTITUTE OF TECHNOLOGY
VARNAMA, VADODARA
YEAR - 2014
SUBMITTED BY
1. SAURABH DAYAL SINGH 130050109106
2. MAULIK DEORE 130050109018
3. ALLAN ABRAHAM 130050109004
4. BHAVIN BARAD 130050109006
5. ASTHA CHAUHAN 130050109014
6. DEVASHREE KUTE 130050109020

2. 2
ACKNOWLEDGEMENT
We are deeply indebted to “ Mr. Saifee Kezarbhai Kanjetawala and Mr. Milan A. Chaudhari
Assistant Professor in Department of Electrical Engineering. At Babariya Institute Of
Technology , Varnama (Vadodara)”. For his inspiring and encouraging guidance without which
this project work could not have been completed in spite 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
throughout the project work. Cordial and earnest thanks to staff of Babariya Institute of
Technology, Varnama (Vadodara) 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.

3. 3
CONTENTS
1. CHAPTER-1 INTRODUCTION
1.1 INTRODUCTION………………………………………………………….…………..04
1.2 THEORETICAL BACK GROUND………………………………………….………..05
1.3 AIM OF THE PROJECT…………………………………………………………….…07
2. CHAPTER-2 PROJECT DESCRIPTION
2.1 BLOCK DIAGRAM……………………………………………………………………08
2.2 BLOCK DESCRIPTION………………………………………………………….…….08
2.3 CIRCUIT DIAGRAM………………………………………………………..………….13
2.4 COMPONENT USED…………………………………………………………...………14
2.5 STEPS OF WORKING…………………………………………………………….……18
2.6 HOW TO CONSTRUCT………………………………………………………...………18
3. CHAPTER-3 FABRICATION PROCESS
3.1 FABRICATION TECHNIQUES ……………………………………………………..….19
3.2 VARIOUS TOOLS AND EQUIPMENTS…………………………………………….…20
3.3 SOLDERING………………………………………………………………………..…… 21
3.4 TIPS WHILE WORKING……………………………………………………………...…22
3.5 PICTURE OF WORKINGMODEL…………………………………………...…………22
3.6 PRECAUTION……………………………………………………………………………23
3.7 TESTING………………………………………………………………………….………23
4. CHAPTER-4 CONCLUSION
4.1 CONCLUSION……………………………………………………………………………24
4.2 RESULT………………………………………………………………………………...…24
4.3 APPLICATION……………………………………………………………………………25
4.4 ADVANTAGES…………………………………………………………………………...25
5 . CHAPTER-5 REFERENCE

4. 4
CHAPTER-1 INTRODUCTION
1.1 INTRODUCTION
A power supply is a device that supplies electrical energy to one or more electric loads. The term is
most commonly applied to devices that convert one form of electrical energy to another, though it
may also refer to devices that convert another form of energy (e.g., mechanical, chemical, solar) to
electrical energy. For electronic circuits made up of transistors and/or ICs, this power source must
be a DC voltage of a specific value.
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. 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 circuits 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.

5. 5
1.2 THEORETICAL BACKGROUND:
A regulated power supply is one that controls the output voltage or current to a specific value; the
controlled value is held nearly constant despite variations in either load current or the voltage
supplied by the power supply's energy source. Every power supply must obtain the energy it
supplies to its load, as well as any energy it consumes while performing that task, from an energy
source. Depending on its design, a power supply may obtain energy from:
1. Electrical energy transmission systems. Common examples of this include power supplies
that convert AC line voltage to DC voltage.
2. Energy storage devices such as batteries and fuel cells.
3. Electromechanical systems such as generators and alternators.
4. Solar power.
A. IC 78XX series
The 78xx is a family of self-contained fixed linear voltage regulator integrated circuits. The 78xx
family is commonly used in electronic circuits requiring a regulated power supply due to their
ease-of-use and low cost. For ICs within the family, the xx is replaced with two digits, indicating
the output voltage . The 78xx line is positive voltage regulators: they produce a voltage that is
positive relative to a common ground. There is a related line of 79xx devices which are
complementary negative voltage regulators. 78xx and 79xx ICs can be used in combination to
provide positive and negative supply voltages in the same circuit. There are common
configurations for 78xx ICs, including 7805 (5 volt), 7806 (6 volt), 7808 (8 volt), 7809 (9 volt),
7810 (10 volt), 7812 (12 volt), 7815 (15 volt), 7818 (18 volt), and 7824 (24 volt) versions. The
7805 is common, as its regulated 5 volt supply provides a convenient power source for
most components. Each device in this series has minimum input voltage to be maintained to get
regulated output.

6. 6
B. REGULATED DC POWER SUPPLY
I. +5V SUPPLY UNIT -Initially 230 V AC supply is reduced to (24V) with the help of a step
down transformer having a capacity of 500mA. Since the input voltage to the regulator IC
should be more than its output voltage, transformer secondary voltage is 24V. This low voltage
is rectified with the help of bridge rectifier. The ripples are minimized with the help of
capacitor filter to get a smooth DC supply.
The regulated DC voltage is obtained by using a regulator IC 7805. In the case of IC 7805, the
unregulated DC voltage is applied to Pin 1, and the output is taken at Pin 3 and Pin 2 is
grounded. The capacitor filter of rating 100µF is connected at the output of regulator IC to
eliminate the voltage oscillations at the output due to the large voltage oscillations at the input
of the regulator.
II. +12V SUPPLY UNIT -Initially 230 V AC supply is reduced to 24Vwith the help of a step
down transformer. This low voltage is rectified with the help off bridge rectifier. Since the
input voltage to the regulator IC should be more than its output voltage, transformer secondary
voltage is 24 V. The ripples are minimized with the help of capacitor filter to get a smooth DC
supply.
The regulated DC output voltage is obtained by using regulator ICs. For regulated +12V DC
supply, IC 7812 is used and for regulated -12V DC supply. In the case of IC 7812 the
unregulated DC voltage is applied to Pin 1, and the output is taken at Pin 3 and Pin 2 is
grounded. The output is taken at Pin 3 and Pin 1 is grounded. The capacitor of 100µF is
connected at the output as shown in figure to eliminate the voltage oscillations at the output
due to the large voltage oscillations at the input of the regulator.

7. 7
1.3 AIM OF A PROJECT
1. To construct a regulated DC power supplies 12 V and 5V source. The power supply
converts the (220-230) V AC into 12 V and 5V DC output.
2. Establishment of regulated DC power supply being used in the labs.

8. 8
CHAPTER-2 PROJECT DESCRIPTION
2.1 BLOCK DIAGRAM
2.2 BLOCK DESCRIPTION

9. 9
1 . S t e p- D o wn Tra ns f o rme r
A step down transformer has more turns of wire on the primary coil and less turns of wire on
the secondary coil. This makes a smaller induced voltage in the secondary coil. Compare this with
a step up transformer.
It is called a step down transformer because the output voltage is smaller than the input voltage. If
the secondary coil has half as many turns of wire then the output voltage will
be half the input voltage.
See the transformer equation. Decreasing the voltage does not decrease the power. As
the voltage goes down, the current goes up.

10. 10
2. Rectifier
There are several ways of connecting diodes to make a rectifier to convert AC to DC. The bridge
rectifier 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.
i. 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 & D3forward
biases & diode D2& D4reverse biases and we get positive cycle. During –ve half wave cycle,
the A becomes –ve and B becomes +ve. Due to this D2 & D4come under forward bias and
diode D1 & D3 are in reverse bias. Therefore , diodes D2 & D4 conduct while diode D1 & D3
don’t. The shape of wave is shown.
Hence, we can say that the bridge wave rectifier give the pulsating DC voltage which are not
suitable for electronic circuit.

11. 11
3. Smoothing
smoothing is performed by 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.
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 large capacitor value must
be doubled when smoothing half- wave rectifier.
So, in this we can conclude that the pulsating DC voltage is applied to the smoothing capacitor.
This smoothing capacitor reduces the pulsating in the rectifier Dc output voltage. The smooth DC
output has a small ripple. It is suitable circuits.

12. 12
4. Regulator
The regulator is a circuit that helps maintains a fixed or constant output voltage. Changes in the
load or the AC line voltage will cause the output voltage to vary. Most electronic circuits cannot
withstand the variations since they are designed to work properly with a fixed voltage. The
regulator fixes the output voltage to the desired level then maintains that value despite any output
or input variations. Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or
variable output voltages. They are also rated by the maximum current they can pass. Negative
voltage regulators are available, mainly for use in dual supplies. Most regulators include some
automatic protection from excessive current ('overload protection') and overheating ('thermal
protection'). Many of the fixed voltage regulator ICs has 3 leads and look like power transistors,
such as the 7805 +5V 1A regulator .They include a hole for attaching a heat sink if necessary.

13. 13
2.3 CIRCUIT DIAGRAM
]

14. 14
2.4 COMPONENT USED
1. CAPACITOR:- A capacitor is a passive two-terminal electrical component used to
store energy electro statically in an electric field. The 'non- conducting' dielectric acts to
increase the capacitor's charge capacity. A dielectric can be glass, ceramic, plastic film, air,
paper, mica, etc. Capacitors are widely used as parts of electrical circuits in many common
electrical devices. A capacitor stores energy in the form of an electrostatic field between its
plates.
If a battery has been attached to a capacitor for a sufficient amount of time, no current can
flow through the capacitor. However, if an accelerating or alternating voltage is applied across
the leads of the capacitor, a displacement current can flow. The SI unit of capacitance is
the farad (F), which is equal to one coulomb per volt (1 C/V). Typical capacitance values
range from about 1 pF (10−12 F) to about 1 mF (10−3 F). We have used 100uF capacitor.
2. DIODE 1N7001:-In electronics, a diode is a two-terminal electronic component with
asymmetric conductance; it has low resistance to current in one direction, and high resistance
in the other. Today, most diodes are made of silicon, but other semiconductors such
as selenium or germanium are sometimes used.
The most common function of a diode is to allow an electric current to pass in one direction
(called the diode's forward direction), while blocking current in the opposite direction
(the reverse direction). Thus, the diode can be viewed as an electronic version of a check
valve. This unidirectional behavior is called rectification, and is used to convert alternating
current to direct current, including extraction of modulation from radio signals in radio
receivers—these diodes are forms of rectifiers.

15. 15
3. PRINTED CIRCUIT BOARD :- (PCB) mechanically supports and electrically
connects electronic components using conductive tracks, pads and other features etched from
copper sheets laminated onto a non-conductive substrate. PCBs can be single sided (one
copper layer), double sided (two copper layers) or multi-layer. Conductors on different layers
are connected with plated-through holes called bias. Advanced PCBs may contain
components - capacitors, resistors or active devices - embedded in the substrate.
Printed circuit boards are used in all but the simplest electronic products. Alternatives to
PCBs include wire wrap and point-to-point construction. PCBs require the additional design
effort to lay out the circuit but manufacturing and assembly can be automated. Manufacturing
circuits with PCBs is cheaper and faster than with other wiring methods as components are
mounted and wired with one single part. Furthermore, operator wiring errors are eliminated.
4. 12-0-12 TRANSFORMER: - The step down transformer high voltage AC into low voltage
AC. By step down transformer we can take different values of voltage at output. In this
project we have use 12-0-12 step down transformer. 12-0-12 means that the voltage or the
potential difference (pd.) between each of the end terminals of the secondary winding and the
mid-point of the secondary winding of the transformer is 12V. And, between the two ends of
the secondary winding, you will get 12 + 12 = 24V. 500mA means the current delivery
capability of the secondary winding of the transformer.

16. 16
5. IC7812:- IC7812 is a famous IC which is being widely used in 12V voltage regulator
circuits.. We only need to use two capacitors, one on the input and second one on the output
of 7812 in order to achieve clean voltage output and even these capacitors are optional to use.
To achieve 12V 1A current, 7812 should be mounted on a good heat sink plate. 7812 has built
in over heat and short circuit protection which makes it a good choice for making power
supplies. High current 7812 voltage regulator can be constructed by adding a transistor to
increase load current capability.
6. IC7805:- 7805 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed
linear voltage regulator ICs. The voltage source in a circuit may have fluctuations and would
not give the fixed voltage output. The voltage regulator IC maintains the output voltage at a
constant value. The xx in 78xx indicates the fixed output voltage it is designed to provide.
7805 provides +5V regulated power supply. Capacitors of suitable values can be connected at
input and output pins depending upon the respective voltage levels.
Pin no Function Name
1 Input voltage (5v-18v) Input
2 Ground (0v) Ground
3 Regulated output;
5v (4.8v-5.2v)
Output

17. 17
12-0-12 TRANSFORMER 100µF CAPACITOR
PRINTED CIRCUIT BOARD(PCB) 1N7001 DIODE
IC7812 IC7805

18. 18
2.5 STEPS OF WORKING
1. Choose the circuit diagram.
2. Studying each block of circuit and it is work, input and output.
3. Start to construct the circuit and make improvements on it.
2.6 HOW TO CONSTRUCT
1. First of all read the given manual thoroughly and study 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.
2. Identification of resistors is done by color-coding. The color band on each resistor
corresponds to its exact value.
3. 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.
4. 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?
5. If yes, only then proceed further to actually mounting and soldering the parts refer to
“Soldering Instructions” section.
6. 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.
7. Start from left most corner of PCB and solder the components one by one on their correct
position of PCB.
8. 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.
9. 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.

19. 19
CHAPTER-3 FABRICATION PROCESS
3.1 FABRICATING TECHNIQUES
The fabricating techniques used in this project can be broadly classified into
1. Mechanical fabricating :- consisting of mechanical design.
2. Electrical fabricating :- consisting of electrical design i.e. making PCB, soldering, is making
connection correctly etc.

20. 20
3.2 VARIOUS TOOLS AND EQUIPMENTS REQUIRED FOR FABRICATION
WIRE CUTTER SOLDER FLUX PASTE
SOLDERING WIRE DE SOLDERING IRON
DIGITAL MULTI METER SOLDERING IRON

21. 21
3.3 SOLDERING
Soldering 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. soldering is characterized by the melting point of the filler
metal, which is below 4000C (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 up to 5000 years ago in Mesopotamia

22. 22
3.4 TIPS WHILE WORKING
Soldiering 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 heat sinks. Heat sinks 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 anymore than a few tenths of an ohm, then it may be a
good idea to re solder 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.
3.5 PICTURE OF WORKING MODEL

23. 23
3.6 PRECAUTIONS
1 . Mount the components at the appropriate places before soldering.
2 . Follow the circuit description and components details, leadsidentification etc. Do not start
soldering before making it confirm that all components are mounted at right place.
3. Do not use a spread solder on board, it may cause short circuit.
4. Do not sit under the fan while soldering.
5. Position the board so that gravity tends to keep the solder where you want it.
6. Do not over heat the components at the board. Excess heat may damage the component or
board.
7. The board should not vibrate while soldering otherwise you have a dry or cold joint.
8 . Do not put the kit under or over voltage source. Be sure about the voltage either dc or
ac while operating the gadget.
3.7 TESTING
This testing step comes after the fabrications process. First of all we have tested the soldering
section of power supply, after that in the this we have checked that we are receiving the output
required or not, i.e. 5V and 12V from the power supply section.
After finding that the power supply section is working as per our requirement we gone through the
whole circuit and check if there are no loosened wires, breaking of tracks etc.

24. 24
CHAPTER-4 CONCLUSION
4.1 CONCLUSION
After all work we did on our project we have learned.
1. We always see a DC power supplies in laboratories and a DC charger for example for
mobiles, laptops, cameras and so many thing.
2. It is the first time we learnt about its major stages. We done soldering, used multi meter and
worked with ICs as per our electrical and electronics workshop course.
3. We can convert AC to DC power supply.
4. Step down the voltage by transformer(step down transformer).
5. It is the first time that we deal with transformer in these details .
6. We have studied how voltage regulator works in detail .
7. It is the first time we deal with many IC’s.
4.2 RESULT
1. We have obtained the output a regulated DC power supplies 12 V and 5V source at
output terminal.
2. The power supply converts the (220-230) V AC into 12 V and 5V DC output.

25. 25
4.3 APPLICATION
1. Automation
2. Data Processing
3. Electro mobility
4. Industrial
5. Lighting
6. Motorcycles, E-Bikes and Small Electric Vehicles
7. Power Management
8. Renewable Energy
9. Smart Grid
10. Motor Control & Drives
4.4 ADVANTAGES
1. 78xx series ICs do not require additional components to provide a constant, regulated source
of power, making them easy to use.
2. Economical and efficient uses of space.
3. 78xx series ICs have built-in protection against a circuit drawing too much power.
4. They have protection against overheating and short-circuits, making them quite robust in most
applications.

26. 26
REFERENCES
1. Peter ,Kurscheidt , leistungs elektronik,1977
2. Power electronic books (Mohammad Rasheed)
3. Basic Electronics (J S Katre)
4. Mini Projects books
5. www.wikipedia.com
6. www.circuitstoday.com
7. electronics.howstuffworks.com
8. www.poweresim.com
9. www.technologystudent.com
10. www.engknowledge.com