“DIGITAL POWER SUPPLY USING LM317”

A Major Project ReportSubmitted partial fulfillment of the requirement for the award of the

Degree of

Bachelor of Engineering

In

Electrical & Electronics Department

Of

RAJIV GANDHI TECHNOLOGICAL UNIVERSITY

BHOPAL (MP)

SUBMITTED BY

NIPUL MAKHIJA

Department of Electrical and Electronics

SAM College of Engineering and Technology, Bhopal

2010 – 11

DECLARATION

We hereby declare that the work that is being presented in the project report

entitled “DIGITAL POWER SUPPLY USING LM 317” in partial

fulfillment of the requirement for the award of degree of Bachelor of

Engineering in Electrical & Electronics is an authentic record of our own

work carried out under the able guidance of Mr. Mangesh Shelke (HOD

Electrical department). The work has been carried out at SAM College of

Engineering and Technology, Bhopal.

The matter embodied in the report has not been submitted for the award of

any other degree or diploma.

NIPUL MAKHIJA (0188EX071031)

SAM COLLEGE OF ENGINEERING AND TECHNOLOGY, BHOPAL

CERTIFICATE

This is to certify that Nipul Makhija student of Fourth Year Bachelor of

Engineering (Electrical & Electronics Department) of SAM College of

Engineering and Technology, Bhopal have successfully completed their

Major Project “DIGITAL POWER SUPPLY USING LM317” in partial

fulfillment of the requirement for the award of degree of Bachelor of

Engineering in Electronics & Communication Department of Rajiv Gandhi

Technological University, Bhopal (MP) in the session 2010-11.

(Mr. Sumit Tiwari) Project Guide

Head of EX Deptt. Director, SAMCET, Bhopal

ACKNOWLEDGEMENT

We express our deep sense of gratitude to our respected and learned

guides Dr. R.K. Ghai (Director) SAM College of Engineering &

Technology, Bhopal for their valuable help and guidance. We are thankful to

them for the encouragement they have given us in completing the project.

We are also grateful to our respected Mr. Mangesh Shelke HOD (EX) SAM

College of Engineering & Technology, Bhopal for permitting us to utilize all

the necessary facilities of the institution.

We are also thankful to all the other faculty & staff members of our

department for their kind co-operation and help.

Lastly, we would like to express our deep appreciation towards our

classmates and our indebtedness to our parents for providing us the moral

support and encouragement.

Nipul Makhija (0188EX071031)

CONTENTS

1. Introduction……………………………………………………………1

2. Working Principle…………………………………………………….3

3. Circuit Diagram……………………………………………………….5

4. Part List……………………………………………………………….. 8

5. IC 89C51 Microcontroller …………………………………………..10

6. LM317 ………………………………………………..………………..11

7. Steps of Project Making……………………………………………13

8. Application of LM317……………………………………………….14

9. PCB Manufacturing Process ………..…………………………..16

10.Component descriptions ………………………………..……...…18

11.Relays ………………………………………………….…………..19

12. Digital Multimeters …………………………………………….….20

13.Chronology …………………………………………………………21

14.Precaution…………………………………………………………….22

15.Conclusion…………………………………………………………...23

16.Bibliography ………………………………………………………...24

INTRODUCTION

Here’s the project which gives out various output voltages and this voltage

can be easily controlled by two switches. The switches are connected to P3.0

and P3.1.

The variable voltages are obtained with help of the LM317. This IC is a

variable voltage regulator IC which can give regulated output from 1.2v to

37v. This voltage regulator can withstand upto 1.5A of current. Since

LM317 is protected against short-circuit, no fuse is necessary. Thanks to

automatic thermal shutdown, it will turnoff if heating excessively. Although

this IC is capable of delivering upto 37v, this circuit is designed to give upto

18v.

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This is the basic circuit with an LM317. The output voltage is selected using

two resistors. Normally R1 is chosen to be around 220R or 240R and I am

using 240ohms. The formula for calculating the value of R2 is V = 1.25(1+

(R2/R1)) or to put it another way R2 = R1 ((V/1.25)-1).

For example to get an output voltage of 8.5v.   R2 = 220((8.5/1.25)-1) =

1276 ohms. The nearest preferred value to this would be 1K3.

Setting R2 to zero, i.e. Grounding the Adjust pin, will cause the output

voltage to drop to 1.25v.

By adjusting the value of this R2 resistor we can obtain a variable voltage at

the output. This is done by the microcontroller with help of the relays.

2

WORKING

In PIC we are controlling eight RELAYS different variable resistances are

connected in the output of the relays. Relays are switching according to the

selected voltages .When relay 1 is operate Then the resistance 1 is connected

in the LM 317 pin No 1 then the output is 1.5 volt . And So on .according to

time. A capacitor 1 uf is connected in between 9 and 31 pin and pin No 9 is

connected to ground through 100 K ohm resistance .The pin No 20 is

connected to ground and pin No 40 is connected to Vcc. For time reading

purpose we are using Real time clock. Crystal 3.58 MHz is connected to pin

No 1 and 2 of RTC and Pin No 8 of RTC is connected to Vcc. A 3 v Battery

is connected between pin 3 and 4 of RTC for time back up purpose. Real

time Clock IC is 8 pin. Pin No 5, 6, 7 of RTC are connected to 10, 11, 12

pin of Atmel 89c51 microcontroller .For Display purpose LCD is used.

LCD is a 15 pin display device. Pin No 1 and 5 of LCD is connected to

ground. pin No 35 ,34, 33,32,27 and 28 of LCD are connected to pin No

11,12,13, 14 ,6,and 4 respectively of microcontroller . A 20 M Hz crystal

and a 0.1 uf capacitor and a 10 K ohm resistance is connected between pin

No 18 and 19 of the microcontroller. Switch S4 is connected to pin NO 4 of

micontroller for set the clock and timer. Switch S3 is connected on pin No 3

of microcontroller for OK clock and timer. Switch 2 is connected on pin 2

for UP time. Switch S1 is connected on pin 1 for down clock and timer. Pin

no 12, 13, 14, 15, 16, 17 and 18 of microcontroller are output pins to operate

the relays. These pins are connected in the base of transistors T1 to T8

through 1.2 k ohm resistances R1 to R8. The emitter of all the transistors

are connected to ground and collector is connected to the relay.

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Collector is connected to drain through 680 ohm resistance and LED and

then drain is connected to the relays Relay 1 to Relay 8.

All the electronic circuits work on DC power supply. So we are requiring a

rectifier circuit which gives pure DC supply. Rectifiers are two types’ half

wave rectifier and full wave rectifier. Full wave rectifier gives good

performance then half wave rectifier. We are using center tapped

transformer full wave rectifier

In the Rectifier circuit step-down transformer is used which converts

230 volt AC into 9 volt AC. This 9 volt AC is converted in to DC with

the help two diodes. And this DC is not pure then DC is filtered

with the help of electrolytic condenser 2200 uf . Before regulation 9v

is double filtered through 0.1 uf ceramic capacitor. Final output is 9v DC.

This 9 v is regulated by using 7805 for 5 v regulation. 5v is double filtered

by using ceramic capacitor 0.1 uf.

4

PART LIST

1. IC 89C51 MICROCONTROLLER (PLD)

2. LM 317 VOLTAGE REGULATING

3. TRANSISTER BC547

4. RELAY 6 V ELECTROMAGNETIC

5. RESISTANCE 4.7 K

6. IC BASE

7. IC 7805

8. RELAY

9. P.C.B

10. L.E.D

11. TRANSFORMER 9 v

12. DIODES IN4007

13. ELECTROLYTIC CAPACITOR 1000 uf

14. L.C.D DISPLAY single line 16 character

15. TACTILE SWITCH 15 v

16. RIBBON WIRE

17. 12 M Hz CRYSTAL

8

18. CERAMIC CAPACITOR 0.1 uf

19. CRYSTAL 3.57 M Hz

20. CRYSTAL 4 M Hz

21. PLUG

22. SOLDER WIRE

23. SOLDER PASTE

24. WOODEN BOARD

25. SOLDERING IRON

26. SCREWS

9

IC 89C51 MICROCONTROLLER (PLD)

The 89C51 is ideal for learning micro controllers, as a lot of tutorial material

and free tools like Assemblers, source code library, 89c51 manuals and

development board designs are available on the Internet for the purpose. The

AT899C51 is a CMOSS 8-bit micro controller unit. Its main features are

1. Compatibility with Intel MCS.51 (8085 family) products.

2. 4KB internal Flash EEPROM program memory with endurance for 1000

erase –write operations.

3. Fully static operation from 0 to 24 MHz.

4. 128 x 8-bit internal RAM.

5. Two 16- bit timers/counters.

6. 32 programmable I/O lines arranged as four ports.

7. Six interrupt sources.

8. Programmable serial I/O channel.

9. Low-power idle and power down modes.

10

LM317

LM317 is the standard part number for an integrated three-terminal adjustable linear voltage regulator. LM317 is a positive voltage regulator supporting input voltage of 3V to 40V and output voltage between 1.25V and 37V. A typical current rating is 1.5A although several lower and higher current models are available. Variable output voltage is achieved by using a potentiometer or a variable voltage from another source to apply a control voltage to the control terminal. LM317 also has a built-in current limiter to prevent the output current from exceeding the rated current, and LM317 will automatically reduce its output current if an overheat condition occurs under load. LM317 is manufactured by many companies, including National Semiconductor, Fairchild Semiconductor, and STMicroelectronics.

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Although LM317 is an adjustable regulator, it is sometimes preferred for high-precision fixed voltage applications instead of the similar LM78xxdevices because the LM317 is designed with superior output tolerances. For a fixed voltage application, the control pin will typically be biased with a fixed resistor network, a Zener diode network, or a fixed control voltage from another source. Manufacturer datasheets provide standard configurations for achieving various design applications, including constant current sources and the use of a pass transistor to achieve regulated output currents in excess of what the LM317 alone can provide.

LM317 is available in a wide range of package forms for different applications including heat sink mounting and surface-mount applications. Common form factors for high-current applications include TO-220 with part number LM317T and TO-3 with part number LM317K. LM317 is capable of dissipating a large amount of heat at medium to high current loads and the use of a heat sink is recommended to maximize the lifespan and power-handling capability.

LM337 is the negative voltage complement to LM317 and the specifications and function are essentially identical, except that the regulator must receive a control voltage and act on an input voltage that are below the ground reference point instead of above it.

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STEPS OF PROJECT MAKING

The following steps have been followed in carrying out the project

1. Study the books on the relevant topic.

2. Understand the working of the circuit.

3. Prepare the circuit diagram.

4. Prepare the list to components along with their specification

estimate .the cost and procure them after carrying out market survey.

5. Plan and prepare PCB for mounting all the components.

6. Fix the components on the PCB and solder them.

7. Test the circuit for the desired performance.

8. Trace and rectify faults if any.

9. Give good finish to the unit.

10. Prepare the project report.

13APPLICATION OF LM317

DUAL VARIABLE POWER SUPPLY USING LM317

This project shows how to build a Dual Variable Power   Supply  using

LM317 and LM7805. It has two different outputs. One stable at 5V and one

Variable, rated at 1 ampere each. The power comes from a transformer.

Schematic and PCB is available on Eagle format.

14LEAD ACID BATTERY CHARGER CIRCUIT

Here is a lead acid battery charger circuit using IC LM317. The IC here

Provides the correct charging voltage for the battery. A battery must be

Charged with 1/10 its Ah value. This charging circuit is designed based on

This fact. The charging current for the battery is controlled by Q1, R1, and R4

And R5. Potentiometer R5 can be used to set the charging current. As

The battery gets charged the the current through R1 increases.

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PCB MANUFACTURING PROCESS

LAYOUT DESIGN:

When designing the layout one should decide the minimum size (component body length and weight). Before starting to design the layout have all the required components in hand so that an accurate assessment of space can be made. Other space consideration includes easy access path to present components on the board.

It might be necessary to turn some components round to a different angular position so that terminals are closer to the connections of the components. The scale can be checked by positioning the components on a squared paper. If any connections cross, then one can reroute to avoid such condition.

All common or earth lines should ideally be connected to a common line routed around the perimeter of the layout. This will act as the ground plane.

Plan the layout as if looking at the top side to this board first this should be translated inverse later for the etching.

There are basically two ways one can affect the copper interconnections pattern on the board. The first is the removal of only the amount of copper necessary to isolate the junctions resulting in the large areas of copper. The second is to make the interconnection pattern looking more like conventional point to point wiring by routing uniform width of copper from component to component.

16ETCHING PROCESS:

Etching process requires the use of acid resistant dishes and running water supply. Ferric chloride is the most used solution but other chemicals such as ammonium sulphate can be used. Nitric acid can be used but in general it is not used due to poisonous fumes.

The pattern prepared is glued to the copper surface of the board. The pattern is laid firmly on the copper. Use a very sharp knife to cut round the pattern carefully to remove the paper corresponding to the required copper pattern areas.

The board should not be left in the bath a moment longer than is needed to remove just the right amount of copper.

Drilling is one of those operations that calls for great care because most of the holes will be made by a very small drill. For most purposes a 1mm drill is used. Drill all holes with this size first those that need to be larger can be easily drilled again with the appropriate lager size.

COMPONENT ASSEMBLES:

From the greatest variety of electronic components available today, which runs into tens of thousands of different types it, is often a perplexing task to know which is the right task for a given job.

When fitting each group of components mark off each one on the components it’s as it is fitted and if we have to leave the job we know where to recommence.

All the component before mounting is rubbed with sand paper so that oxide layer is removed from their tips. Now they are mounted according to the component layout.

SOLDERING:

Flux is applied to the tips and then the components are soldered with the help of soldering iron. Attention should be given while soldering the components because prolonged application of soldering iron can internally damage the components.

17COMPONENT DESCRIPTION

RESISTANCE

Resistors and resistive networks are extensively used in electronic circuits and measurement work. The foremost properties of material used in the construction of resistors meant for precision work are: stability or performance with time two resistance temperature co efficient low thermoelectric elf. With copper high resistively resistance to oxidation corrosion and moisture case of manufacture and low cost.

Material Used for Resistors: -The most widely used material for precision resistors are:

Mangnin:-It is an alloy of copper manganese and nickel and is universally used

as resistance material for precision resistors and for resistance measuring apparatus. It has a normal composition of 84% copper 12% manganese and 4% nickel. The foremost property of managing is that it has almost a zero temperature coefficient of resistance near about room temperature.

Constantine: -

These are series of alloy of nickel & copper containing 40 to 60 percent nickels, with a small amount of manganese to improve their mechanical properties. Constantan has a resistively at ordinary temperature of about 25times that of copper is corrosion resistant inexpensive & easy to work. It also finds application is resistors of 1000 -- & above as in voltmeter Multipliers.

Nickel Chromium alloys: -

These alloys have a somewhat higher temperature coefficient of resistance than that of Mangnin and constantan these alloys cannot be uses in precision resistance Nichrome has a very high resistively and resists corrosion even at very high temperature.

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Relays

A relay is an electrically operated switch. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and they are double throw (changeover) switches.

Relays allow one circuit to switch a second circuit which can be completely separate from the first. For example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit. There is no electrical connection inside the relay between the two circuits, the link is magnetic and mechanical.

The coil of a relay passes a relatively large current, typically 30mA for a 12V relay, but it can be as much as 100mA for relays designed to operate from lower voltages. Most ICs (chips) cannot provide this current and a transistor is usually used to amplify the small IC current to the larger value required for the relay coil. The maximum output current for the popular 555 timer IC is 200mA so these devices can supply relay coils directly without amplification.

Most relays are designed for PCB mounting but you can solder wires directly to the pins providing you take care to avoid melting the plastic case of the relay.

The relay's switch connections are usually labeled COM, NC and NO:

COM = Common, always connect to this; it is the moving part of the switch.

NC = Normally Closed, COM is connected to this when the relay coil is off.

NO = Normally Open, COM is connected to this when the relay coil is on.

ELECTROMAGNETIC RELAY

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Digital MULTIMETER

All digital meters contain a battery to power the display so they use Virtually no power from the circuit under test. This means that on their DC voltage ranges they have a very high resistance (usually called input impedance) of 1M or more, usually 10M , and they are very unlikely to affect the circuit under test.

Typical ranges for digital multimeters like the one illustrated: (the values given are the maximum reading on each range)

DC Voltage: 200mV, 2000mV, 20V, 200V, 600V. AC Voltage: 200V, 600V. DC Current: 200µA, 2000µA, 20mA, 200mA, 10A*. *The 10A range is usually unused and connected via a special

socket. AC Current: None. (You are unlikely to need to measure this). Resistance: 200 , 2000 , 20k , 200k , 2000k , Diode Test.

Digital meters have a special diode test setting because their resistance ranges cannot be used to test diodes and other semiconductors

20

CHRONOLOGY

The following steps have been followed in carrying out the project

11. Study the books on the relevant topic.

12. Understand the working of the circuit.

13. Prepare the circuit diagram.

14. Prepare the list to components along with their specification estimate .the cost and procure them after carrying out market survey.

15. Plan and prepare PCB for mounting all the components.

16. Fix the components on the PCB and solder them.

17. Test the circuit for the desired performance.

18. Trace and rectify faults if any.

19. Give good finish to the unit.

20. Prepare the project report.

21

PRECAUTION 1. Switch off the main switch or branch circuit breaker before opening the

Switchboard for wiring.

2. Before touching any wire, make sure it is not live. Use a neon tester for the purpose. Wear rubber shoes/slippers.

3. Switch off the circuit, when it is not in use, to conserve the battery.

4. Check the wiring connections to switchboard before switching the on the mains.

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CONCLUSION

MAJOR PROJECT being an integral part of engineering curriculum

provides not only easier understanding but also helps acquaint an individual

with technologies. It exposes an individual to practical aspect of all things

which differ considerably from theoretical models. During my project

making, I gained a lot of practical knowledge which otherwise could have

been exclusive to me. The practical exposure required here will pay rich

dividends to me when I will set my foot as an Engineer.

The project at SAMCET was altogether an exotic experience, since work,

culture and mutual cooperation was excellent here. Moreover fruitful result

of adherence to quality control awareness of safety and employees were fare

which is much evident here.

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BIBLIOGRAPHY

www.google.com

www.texas.com

www.efymeg.com

www.efy.com

www.micro.edu/echips.com

www.answers.com

www.google.com

www.national.com

www.ascom.com

www.electronicsconsulting.co.uk/

www.radarsystem.com

www.electronicsproject.com

www.scienceproject.com

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