variable power supply with digital control with seven segments display

A

PROJECT STAGE-I REPORT

ON

“Variable Power Supply with Digital Control with

seven segments display” Submitted in the partial fulfillment of the award of

Bachelor of Technology

(Rajasthan Technical University, Kota)

In

ELECTRICAL ENGINEERING

2013-2014

Guided by: Submitted by:

Mr. Shivraj Sharma PRITAM SOLANKI(EE/10 /85) Assistant Professor PRANSHU TIWARI(EE/10/83) Department of Electrical Engg. PIYUSH SHARMA (EE/10/82) PRASHANTJAIN (EE/10/140) 4th year, VIII SEM,EE

DEPARTMENT OF ELECTRICAL ENGINEERING POORNIMA COLLEGE OF ENGINEERING

ISI-06, RIICO INSTITUTIONAL AREA SITAPURA, JAIPUR –302 022

DEPARTMENT OF ELECTRICAL ENGINEERING

POORNIMA COLLEGE OF ENGINEERING

This is to certify that project entitled “ Variable Power Supply with Digital Control with seven segments displaybeen carried out by PRITAM SOLANKI, PRANSHU TIWARI, PIYUSH SHARMA, PRAS HANT JAIN in partial fulfilment of the degree of Bachelor of Technology in Kota, during the academic year 2013-2014elsewhere for the award of any other degree. The work has been found satisfactory and is approved for submission.

Mr. SHIVRAJ SHARMA M r. HARBEER SINGH Project Guide Project Coordinator

i


POORNIMA COLLEGE OF ENGINEERING

JAIPUR -302022

CERTIFICATE

Variable Power Supply with Digital Control with seven segments displayPRITAM SOLANKI, PRANSHU TIWARI, PIYUSH SHARMA, PRAS HANT JAIN

in partial fulfilment of the degree of Bachelor of Technology in Electrical Engineering of Rajasthan Technical University, 4. To the best of my knowledge and belief this work has not been submitted

elsewhere for the award of any other degree. The work has been found satisfactory and is approved for submission.

r. HARBEER SINGH Mr. VAIBHAV JAIN Project Coordinator HOD, EE Department


Variable Power Supply with Digital Control with seven segments display” has PRITAM SOLANKI, PRANSHU TIWARI, PIYUSH SHARMA, PRAS HANT JAIN under my guidance

of Rajasthan Technical University, . To the best of my knowledge and belief this work has not been submitted

elsewhere for the award of any other degree. The work has been found satisfactory and is approved for submission.

Dr. R.P. RAJORIA Campus Director (PCE)

PCE/EE/ii

ACKNOWLEDGEMENT

We take this opportunity to express our deep sense of gratitude and respect towards our guide,

Mr. Shivraj Sharma Assistant Professor, Department of Electrical Engineering, Poornima

College of Engineering. We are very much indebted to him for the generosity, expertise and

guidance; we have received from him while working on this project and throughout our studies.

Without his support and timely guidance, the completion of our seminar would have seemed a

farfetched dream. In this respect we find ourselves lucky to have him as our guide. He has

guided us not only with the subject matter, but also taught us the proper style and technique of

working and presentation.

We are grateful to our respected Dr. R. P. Rajoria (Campus Director), Dr. Om Prakash

Sharma (Principal,PCE), Mr. Vaibhav Jain (HOD Department Electrical Engineering),

Mr. Harbeer Singh (Seminar Coordinator), for guiding us while working on project.All the

staff members of the Department of Electrical Engineering for their constant encouragement and

all those who helped us directly or indirectly in our endeavor.

PRITAM SOLANKI PRANSHU TIWARI PIYUSH SHARMA PRASHANT JAIN

PCE/EE/iii

PREFACE

Today the world swiftly changing, there are multiple challenges faced by us. Surly it is the

knowledge through technology, which makes us to overcome them. The project stage-I report,

which is an integral part of four years engineering program provides a platform to all the student

to augment their technical study through practical revelation. It is the time, which is effectively

used by students to enhance their interaction with technical atmosphere. The project stage-I is

obligatory as per university course outline. This report is based on work done and theory gained

during analysis of the topic. The report basically introduces working of project in detail.

Variable Power Supply with Digital Control with seven segments display is one of the

applications of electronics to increase the facilities of life. It is facilitates the operation of voltage

regulators around the electronics lab. It provides a system that is simple to understand and also to

operate, a system that would be cheaper and affordable. It adds more comfort to everyday living

by removing the inconvenience of having to move around to operate a fan regulator.

We have been fortunate to get a chance for making the project stage-I under guidance of Mr.

Shivraj Sharma (Assistant Professor, Electrical Engineering Department.) & our project

coordinator Mr. Harbeer Singh.

PRITAM SOLANKI

PRANSHU TIWARI PIYUSH SHARMA PRASHANT JAIN

PCE/EE/IX

ABSTRACT

Variable Power Supply with Digital Control with seven segments display is the most

frequently used device in electronic workshops and laboratories is a universal power supply

that provides a variable, fluctuation-free output. Here we present a variable power supply

with digital control that is simple and easy to construct. The circuit is built around an

adjustable 3-terminal positive-voltage regulator IC LM317, CMOS decade counter IC

CD4017, timer IC NE555 and 3-terminal fixed negative-voltage regulator LM7912. The AC

mains supply is stepped down by transformer X1 to deliver a secondary output of 12V-0-12V

AC, 1A. The output of the transformer is rectified by a full-wave rectifier comprising diodes

D1 through D4. Capacitors C1 through C4 are connected in parallel to rectifier diodes to

bypass undesired spikes and provide smooth and fluctuation-free power. Capacitors C5 and

C13 are used as filters to eliminate ripple. Here both negative and positive half cycles are

used to obtain positive as well as negative DC output. LED1, along with current-limiting

resistor R1, is used for mains ‘on’ indication. Timer IC NE555 (IC1) is wired as an astable

multivibrator. It generates clock pulses when switch S2 is pressed. IC CD4017 is a decade

ring counter. Each of its ten outputs goes high one by one when a clock pulse is received. The

outputs of IC CD4017 are connected to the bases of transistors T1 through T10, respectively,

as shown in the figure. LED3 through LED11 are used here to indicate the voltage levels. The

collectors of transistors T2 through T10 are connected to presets VR1 through VR9,

respectively, which are used to set the output voltage. Presets VR1 through VR9 are adjusted

to get the desired output voltage. When switch S2 is pressed, the output of IC1 goes high. As

a result, the outputs of IC2 go high one by one as a ring counter. Since presets VR1 through

VR9 are connected at the collectors of transistors T2 through T10, respectively, different

output resistances appear between the adjustable and ground terminals of IC4, resulting in

different output voltages. By using a properly calibrated digital multimeter you can easily

adjust the presets to obtain 1.5V to 12V. Assemble the circuit on any generalpurpose PCB

and enclose it in a suitable cabinet. Use suitable heat-sinks for regulators IC3 and IC4. Since

pin configurations of the regulators are different, never fix both regulators on the same

heatsink. For S2 and S3, using microswitches will enhance the beauty of the unit. LED2 is

used to indicate the negative 12V DC voltage.

PCE/EE/IV

CONTENTS

Certificate …i

Acknowledgement ...ii

Preface …iii

Contents …iv

Figure index …vi

Table index …viii

Abstract …ix

CHAPTER PAGE NO.

1. Introduction 1-1

1.1. Introduction 1

2. Circuit Description 2-4

2.1. Block diagram 2

2.2. Circuit diagram 3

2.3. Working of the circuit 4

3. Component Description 5-25

3.1. Component requirement 5

3.2. Component description 6

3.2.1 Monostable multivibrator (NE 555) 6

3.2.2 Decade counter (CD 4017) 8

3.3.3 LM 79LXX 11

3.3.4 LM 317 15

3.3.5 Regulator section (IC-7809) 18

3.3.6 Transformer 20

3.3.7 Power supply 20

3.3.8 Resistor 20

3.3.9 LED 22

3.3.10 Capacitor 22

3.3.11 Diode 23

3.3.12 Transistor 24

4. Seven segment display 26-28

4.1 Introduction 26

4.2 History 26

PCE/EE/V

4.3 Concept and visual structure 27

4.4 Implementation 27

4.5 Displaying letters 28

5. PCB Designing 29-30

5.1 Printed circuit board 29

6. Soldering of component 31-33

6.1 Introduction 31

6.2 Soldering tools 32

7. Reault and application 34-34

7.1 Result analysis 34

7.2 Specification of the motor 34

7.3 Application 34

7.4 Advantage 34

8. Conclusion 35

Reference 36

PCE/EE/VI

FIGURE INDEX

figure no. Figure name Page no.

2.1 Block Diagram of variable power supply with digital control

2

2.2 Circuit Diagram of variable power supply with digital control

3

3.1 Monostable Multivibrator (NE 555) 6

3.2 Decade counter (CD 4017) 8

3.3 Typical application & connection diagram of LM79LXX 12

3.4 Typical performance characteristics of LM79LXX 14

3.5 Typical applications of LM317 16

3.6 Regulator IC-7809 18

3.7 Step down transformer 20

3.8 Power supply 20

3.9(a) Variable Resistor 21

3.9(b) Fixed Resistor 21

3.10 LED 22

3.11 Electrolytic capacitor 23

3.12 Diode 24

3.13 Transistor 25

4.1 A typical 7-segment LED display component, with decimal point

26

5.1 Copper PCB 29

PCE/EE/VII

5.2 PCB for variable power supply with digital control

30

6.1 Soldering Iron 32

PCE/EE/VIII

TABLE INDEX

Table no. Name Page

3.1 Data sheet of IC-555 07

3.2 Data sheet of DC characteristics of CD 4017 09

3.3 Data sheet of AC characteristics of CD 4017

10

3.4 Data sheet of characteristics of LM79LXX 13

3.5 Data sheet of characteristics of LM317 17

3.6 Data Sheet of IC-7809 19

4.1 Hexadecimal encoding for displaying the digits 0 to F 28

7.1 Results for variable resistors 34

PCE/EE/01

CHAPTER-1

INTRODUCTION

1.1.INTRODUCTION :

Variable Power Supply with Digital Control with seven segments display is the most

frequently used device in electronic workshops and laboratories is a universal power supply

that provides a variable, fluctuation-free output. Here we present a variable power supply

with digital control that is simple and easy to construct. The circuit is built around an

adjustable 3-terminal positive-voltage regulator IC LM317, CMOS decade counter IC

CD4017, timer IC NE555 and 3-terminal fixed negative-voltage regulator LM7912. The AC

mains supply is stepped down by transformer X1 to deliver a secondary output of 12V-0-12V

AC, 1A. The output of the transformer is rectified by a full-wave rectifier comprising diodes

D1 through D4. Capacitors C1 through C4 are connected in parallel to rectifier diodes to

bypass undesired spikes and provide smooth and fluctuation-free power. Capacitors C5 and

C13 are used as filters to eliminate ripple. Here both negative and positive half cycles are

used to obtain positive as well as negative DC output. LED1, along with current-limiting

resistor R1, is used for mains ‘on’ indication. Timer IC NE555 (IC1) is wired as an astable

multivibrator. It generates clock pulses when switch S2 is pressed. IC CD4017 is a decade

ring counter. Each of its ten outputs goes high one by one when a clock pulse is received. The

outputs of IC CD4017 are connected to the bases of transistors T1 through T10, respectively,

as shown in the figure. LED3 through LED11 are used here to indicate the voltage levels. The

collectors of transistors T2 through T10 are connected to presets VR1 through VR9,

respectively, which are used to set the output voltage. Presets VR1 through VR9 are adjusted

to get the desired output voltage. When switch S2 is pressed, the output of IC1 goes high. As

a result, the outputs of IC2 go high one by one as a ring counter. Since presets VR1 through

VR9 are connected at the collectors of transistors T2 through T10, respectively, different

output resistances appear between the adjustable and ground terminals of IC4, resulting in

different output voltages. By using a properly calibrated digital multimeter you can easily

adjust the presets to obtain 1.5V to 12V. Assemble the circuit on any generalpurpose PCB

and enclose it in a suitable cabinet. Use suitable heat-sinks for regulators IC3 and IC4. Since

pin configurations of the regulators are different, never fix both regulators on the same

heatsink. For S2 and S3, using microswitches will enhance the beauty of the unit. LED2 is

used to indicate the negative 12V DC voltage.

PCE/EE/02

CHAPTER-2

CIRCUIT DESCRIPTION

2.1. BLOCK DIAGRAM: The following shows block diagram of how Variable Power Supply with Digital

Control with seven segments display work.

Fig.2.1.Block Diagram of variable power supply with digital control

2.2. CIRCUIT DIAGRAM:

The following shows circuit diagram of wireless speed control of single phase

induction motor.

Fig.2.2.Circuit

PCE/EE/03


Fig.2.2.Circuit Diagram of variable power supply with digital control


of variable power supply with digital control

PCE/EE/04

2.3. WORKING OF THE CIRCUIT:

The most frequently used device in electronic workshops and laboratories is a universal power supply provides a variable, fluctuation-free output. Here we present a variable power supply with digital control that is simple and easy to construct. The circuit is built around an adjustable 3-terminal positive-voltage regulator IC LM317, CMOS decade counter IC CD4017, timer IC NE555 and 3-terminal fixed negative-voltage regulator LM7912. The AC mains supply is stepped down by transformer X1 to deliver a secondary output of 12V-0-12V AC, 1A. The output of the transformer is rectified by a full-wave rectifier comprising diodes D1 through D4. Capacitors C1 through C4 are connected in parallel to rectifier diodes to bypass undesired spikes and provide smooth and fluctuation-free power. Capacitors C5 and C13 are used as filters to eliminate ripple. Here both negative and positive half cycles are used to obtain positive as well as negative DC output. LED1, along with current-limiting resistor R1, is used for mains ‘on’ indication. Timer IC NE555 (IC1) is wired as an astable multivibrator. It generates clock pulses when switch S2 is pressed. The output of IC1 is connected, via an RC network, to the clock input of counter IC CD4017 (IC2). IC CD4017 is a decade ring counter. Each of its ten outputs goes high one by one when a clock pulse is received. The outputs of IC CD4017 are connected to the bases of transistors T1 through T10, respectively, as shown in the figure. LED3 through LED11 are used here to indicate the voltage levels. The collectors of transistors T2 through T10 are connected to presets VR1 through VR9, respectively, which are used to set the output voltage. Adjustable voltage regulator IC LM317 (IC4) develops 1.25V nominal reference voltage (VREF) between its output and the adjustable terminal. The reference voltage appears across resistor R16. When the voltage is constant, a constant current flows through one of the output-setting variable resistors (VRset, VR1 through VR9), giving an output voltage at pin 2 of IC4 as follows: VOUT=1.25(1+VRset/R16). Presets VR1 through VR9 are adjusted to get the desired output voltage. The collector of transistor T1 is directly connected to ADJ terminal (pin 1) of IC4, so the output voltage of IC4 will be the voltage across fixed resistor R16, which is equal to 1.25V. When switch S3 is pressed, pin 3 of IC2 goes high and the output voltage becomes 1.2V. When switch S2 is pressed, the output of IC1 goes high. As a result, the outputs of IC2 go high one by one as a ring counter. Since presets VR1 through VR9 are connected at the collectors of transistors T2 through T10, respectively, different output resistances appear between the adjustable and ground terminals of IC4, resulting in different output voltages. By using a properly calibrated digital multimeter you can easily adjust the presets to obtain 1.5V to 12V. A fixed, negative 12V DC can be obtained by using fixed, negative-voltage regulator IC LM7912 (IC3). Thus the power supply unit can be used for circuits requiring both negative and positive DC voltages. When CD4017 is reset by pressing switch S3, the output voltage becomes 1.2V and all the voltage-indication LEDs turn off. Assemble the circuit on any generalpurpose PCB and enclose it in a suitable cabinet. Use suitable heat-sinks for regulators IC3 and IC4. Since pin configurations of the regulators are different, never fix both regulators on the same heatsink. For S2 and S3, using microswitches will enhance the beauty of the unit. LED2 is used to indicate the negative 12V DC voltage.

PCE/EE/05

CHAPTER-3

COMPONENTS DESCRIPTION

3.1 COMPONENTS REQUIREMENTS:

1. IC NE555 1

2. CD4017 1

3. LM79LXX 1

4. LM317 1

5. LM7809 1

6. IC Base 8 Pin 2

7. IC Base 16 Pin 1

8. IC Base 6 Pin 2

9. Transistor BC-548 1

10. Diode IN4007 6

11. LED 5 mm , Green 3

12. 5 mm , Red 3

13. 5 mm , Yellow 4

14. Capacitor 1000 mfd / 25 V 1

15. 10 mfd / 50 V 1

16. 4.7 mfd / 50 V 1

17. 1 mfd / 63 V 1

18. 0.1 mfd Ceramic 1

19. 0.01 mfd Ceramic 2

20. Variable Resistance 200K 9

21. Resistance 47 Ohms 2

22. 330 Ohms 1

23. 47K 1

24. Transformer 0-12 Volts, 500 ma 1

PCE/EE/06

3.2 COMPONENTS DESCRIPTIONS:

3.2.1 MONOSTABLE MULTIVIBRATOR (NE 555) :

A multivibrator is an electronic circuit used to implement a variety of simple twostate

systems such as oscillators, timers and flip-flops. A monostable multivibrator, as its name

indicates, has a stable state and a quasi-stable state. An external trigger must be applied to

change from the stable state to the quasi-stable state.

Fig 3.1 Monostable Multivibrator (NE 555)

Here, two NE 555 ICs are wired as monostable multivibrators. The trigger to the first

multivibrator is the signals from the infrared receiver module. This multivibrator is used to

delay the clock pulse of the decade counter. The second multivibrator is triggered by the opto

coupler. The LM555/NE555/SA555 is a highly stable controller capable of producing

accurate timing pulses. With monostable operation, the time delay is controlled by one

external resistor and one capacitor. With astable operation, the frequency and duty cycle are

accurately controlled with two external resistors and one capacitor. When the low signal input

is applied to the reset terminal, the timer output remains low regardless of the threshold

voltage or the trigger voltage. Only when the high signal is applied to the reset terminal,

timer's output changes according to threshold voltage and trigger voltage. When the threshold

voltage exceeds 2/3 of the supply voltage while the timer output is high, the timer's internal

discharge Tr. turns on, lowering the threshold voltage to below 1/3 of the supply voltage.

During this time, the timer output is maintained low. Later, if a low signal is applied to the

trigger voltage so that it becomes 1/3 of the supply voltage, the timer's internal discharge Tr.

turns off, increasing the threshold voltage and driving the timer output again at high.

PCE/EE/07

Table 3.1 Data sheet of IC-555

PCE/EE/08

3.2.2 DECADE COUNTER (CD 4017) :

In digital logic and computing, a counter is a device which stores (and sometimes displays)

the number of times a particular event or process has occurred, often in relationship to a clock

signal. Decade counter is a counter that counts through 10 states. It is also known as a mod-

10 counter.

Fig 3.2 Decade counter (CD 4017)

Here, CD 4017 is used as decade counter. Here actually ten outputs are there from which five

are used (Q0 to Q4), Q5 is not used and Q6 is used to reset. The output of monostable

multivibrator (IC1) is used to delay the clock pulse of the decade counter. The CD4017BC is

a 5-stage divide-by-10 Johnson counter with 10 decoded outputs and a carry out bit. The

CD4022BC is a 4-stage divide-by-8 Johnson counter with 8 decoded outputs and a carry-out

bit. These counters are cleared to their zero count by a logical “1” on their reset line. These

counters are advanced on the positive edge of the clock signal when the clock enable signal is

in the logical “0” state. The configuration of the CD4017BC and CD4022BC permits medium

speed operation and assures a hazard free counting sequence. The 10/8 decoded outputs are

normally in the logical “0” state and go to the logical “1” state only at their respective time

slot. Each decoded output remains high for 1 full clock cycle. The carry-out signal completes

a full cycle for every 10/8 clock input cycles and is used as a ripple carry signal to any

succeeding stages.

PCE/EE/09

Table 3.2 Data sheet of DC characteristics of CD 4017

PCE/EE/010

Table 3.3 Data sheet of AC characteristics of CD 4017

PCE/EE/011

3.2.3 LM 79LXX :

The LM320L/LM79LXXAC series of 3-terminal negative voltage regulators features fixed

output voltages of b5V, b12V, and b15V with output current capabilities in excess of 100

mA. These devices were designed using the latest computer techniques for optimizing the

packaged IC thermal/ electrical performance. The LM79LXXAC series, even when combined

with a minimum output compensation capacitor of 0.1 mF, exhibits an excellent transient

response, a maximum line regulation of 0.07% VO/V, and a maximum load regulation of

0.01% VO/mA. The LM320L/LM79LXXAC series also includes, as self-protection circuitry:

safe operating area circuitry for output transistor power dissipation limiting, a temperature

independent short circuit current limit for peak output current limiting, and a thermal

shutdown circuit to prevent excessive junction temperature. Although designed primarily as

fixed voltage regulators, these devices may be combined with simple external circuitry for

boosted and/or adjustable voltages and currents. The LM79LXXAC series is available in the

3-lead TO-92 package, and SO-8; 8 lead package. The LM320L series is available in the 3-

lead TO-92 package. For output voltage other than b5V, b12V and b15V the LM137L series

provides an output voltage range from 1.2V to 47V.

Features:

• Preset output voltage error is less than g5% overload,

line and temperature

• Specified at an output current of 100 mA

• Easily compensated with a small 0.1 mF output

capacitor

• Internal short-circuit, thermal and safe operating area

protection

• Easily adjustable to higher output voltages

• Maximum line regulation less than 0.07% VOUT/V

• Maximum load regulation less than 0.01% VOUT/mA

Fig 3.3 Typical application & connection diagram of LM79LXX

PCE/EE/012

Typical application & connection diagram of LM79LXX

Table 3.4

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Table 3.4 Data sheet of characteristics of LM79LXX

Fig 3.4 Typical performance characteristics of LM79LXX

PCE/EE/014

Typical performance characteristics of LM79LXX

PCE/EE/015

3.2.4 LM 317:

The LM317 series of adjustable 3-terminal positive voltage regulators is capable of supplying

in excess of 1.5A over a 1.2V to 37V output range. They are exceptionally easy to use and

require only two external resistors to set the output voltage. Further, both line and load

regulation are better than standard fixed regulators. Also, the LM317 is packaged in standard

transistor packages which are easily mounted and handled. In addition to higher performance

than fixed regulators, the LM317 series offers full overload protection available only in IC’s.

Included on the chip are current limit, thermal overload protection and safe area protection.

All overload protection circuitry remains fully functional even if the adjustment terminal is

disconnected.

Normally, no capacitors are needed unless the device is situated more than 6 inches from the

input filter capacitors in which case an input bypass is needed. An optional output capacitor

can be added to improve transient response. The adjustment terminal can be bypassed to

achieve very high ripple rejection ratios which are difficult to achieve with standard 3-

terminal regulators. Besides replacing fixed regulators, the LM317 is useful in a wide variety

of other applications. Since the regulator is “floating” and sees only the input-to-output

differential voltage, supplies of several hundred volts can be regulated as long as the

maximum input to output differential is not exceeded, i.e., avoid short-circuiting the output.

Also, it makes an especially simple adjustable switching regulator, a programmable output

regulator, or by connecting a fixed resistor between the adjustment pin and output, the

LM317 can be used as a precision current regulator. Supplies with electronic shutdown can

be achieved by clamping the adjustment terminal to ground which programs the output to

1.2V where most loads draw little current. For applications requiring greater output current,

see LM150 series (3A) and LM138 series (5A) data sheets. For the negative complement, see

LM137 series data sheet.

Features:

• Guaranteed 1% output voltage tolerance (LM317A)

• Guaranteed max. 0.01%/V line regulation (LM317A)

• Guaranteed 1.5A output current

• Adjustable output down to 1.2V

• P(+) Product Enhancement tested

• 80 dB ripple rejection

• Output is short-circuit protected

PCE/EE/016

Fig 3.5 Typical applications of LM317

Table 3.5

PCE/EE/017

Table 3.5 Data sheet of characteristics of LM317

PCE/EE/018

3.2.5 REGULATOR SECTION (7809):

Fig 3.6 Regulator IC-7809

A voltage regulator is an electrical regulator designed to automatically maintain a constant

voltage level. IC 7809 is used here. It is a 9V regulator. It regulates the rectified 12V to 9V.

This 9V is supplied to the whole circuit. These voltage regulators are monolithic integrated

circuits designed as fixed–voltage regulators for a wide variety of applications including

local, on–card regulation. These regulators employ internal current limiting, thermal

shutdown, and safe–area compensation. With adequate heatsinking they can deliver output

currents in excess of 1.0 A. Although designed primarily as a fixed voltage regulator, these

devices can be used with external components to obtain adjustable voltages and currents.

Features:

• Output current up to 1.5 A

• Fixed output voltage of 5V, 6V, 8V, 9V, 10V, 12V,

15V, 18V and 24V available

• Thermal overload shutdown protection

• Short circuit current limiting

• Output transistor SOA protection

PCE/EE/019

Table 3.6 Data Sheet of IC-7809

PCE/EE/020

3.2.6 TRANSFORMER (230/(12-0-12))V:

A transformer is a device that transfers electrical energy from one circuit to another through

inductively coupled conductors — the transformer's coils or "windings". Transformer is used

here to step down the supply voltage to a level suitable for the low voltage components.

The transformer used here is a 230/(12V-0-12V) step down transformer.

Fig 3.7 Step down transformer

3.2.7 POWER SUPPLY:

The power supply supplies the required energy for both the microcontroller and the

associated circuits. It is the most essential part of the circuit because to run its constituent

IC’s circuit has to be provided with power. These IC’s can run on DC power. Hence the

required D.C supply has to be generated.

Fig 3.8 Power supply

3.2.8 RESISTOR:

A resistor is a two-terminal electronic component designed to oppose an electric

current by producing a voltage drop between its terminals in proportion to the current, that is,

in accordance with Ohm's law: V = IR. The resistance R is equal to the voltage drop V across

the resistor divided by the current I through the resistor. A resistor is a passive two-terminal

electrical component that implements electrical resistance as a circuit element. The current

through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus,

PCE/EE/021

the ratio of the voltage applied across a resistor's terminals to the intensity of current through

the circuit is called resistance. The electrical functionality of a resistor is specified by its

resistance: common commercial resistors are manufactured over a range of more than nine

orders of magnitude. When specifying that resistance in an electronic design, the required

precision of the resistance may require attention to the manufacturing tolerance of the chosen

resistor, according to its specific application. The temperature coefficient of the resistance

may also be of concern in some precision applications. Practical resistors are also specified as

having a maximum power rating which must exceed the anticipated power dissipation of that

resistor in a particular circuit: this is mainly of concern in power electronics applications.

Resistors with higher power ratings are physically larger and may require heat sinks. In a

high-voltage circuit, attention must sometimes be paid to the rated maximum working voltage

of the resistor.

Practical resistors have a series inductance and a small parallel capacitance; these

specifications can be important in high-frequency applications. In a low-noise amplifier or

pre-amp, the noise characteristics of a resistor may be an issue. The unwanted inductance,

excess noise, and temperature coefficient are mainly dependent on the technology used in

manufacturing the resistor. They are not normally specified individually for a particular

family of resistors manufactured using a particular technology. A family of discrete resistors

is also characterized according to its form factor, that is, the size of the device and the

position of its leads (or terminals) which is relevant in the practical manufacturing of circuits

using them.

Fig.3.9 (a) Variable Resistor Fig 3.9 (b)Fixed Resistor

PCE/EE/022

3.2.9 LED (Light Emitting Diode):

A light-emitting-diode (LED) is a semiconductor diode that emits light when an electric

current is applied in the forward direction of the device, as in the simple LED circuit. The

effect is a form of electroluminescence where incoherent and narrow-spectrum light is

emitted from the p-n junction.

Fig. 3.10 LED

3.2.10 CAPACITOR

A capacitor (originally known as condenser) is a passive two-terminal electrical

component used to store energy in an electric field. The forms of practical capacitors vary

widely, but all contain at least two electrical conductors separated by a dielectric (insulator);

for example, one common construction consists of metal foils separated by a thin layer of

insulating film. Capacitors are widely used as parts of electrical circuits in many common

electrical devices.

When there is a potential difference (voltage) across the conductors, a static electric

field develops across the dielectric, causing positive charge to collect on one plate and

negative charge on the other plate. Energy is stored in the electrostatic field. An ideal

capacitor is characterized by a single constant value, capacitance, measured in farads. This is

the ratio of the electric charge on each conductor to the potential difference between them.

PCE/EE/023

Fig 3.11 Electrolytic capacitor

The capacitance is greatest when there is a narrow separation between large areas of

conductor; hence capacitor conductors are often called "plates," referring to an early means of

construction. In practice, the dielectric between the plates passes a small amount of leakage

current and also has an electric field strength limit, resulting in a breakdown voltage, while

the conductors and leads introduce an undesired inductance and resistance.

Capacitors are widely used in electronic circuits for blocking direct current while

allowing alternating current to pass, in filter networks, for smoothing the output of power

supplies, in the resonant circuits that tune radios to particular frequencies, in electric power

transmission systems for stabilizing voltage and power flow, and for many other purposes.

3.2.11 DIODE:

A diode is a two-terminal electronic component with asymmetric transfer

characteristic, with low (ideally zero) resistance to current flow in one direction, and high

(ideally infinite) resistance in the other. A semiconductor diode, the most common type

today, is a crystalline piece of semiconductor material with a p-n junction connected to two

electrical terminals. A vacuum tube diode, now rarely used except in some high-power

technologies and by enthusiasts, is a vacuum tube with two electrodes, a plate (anode) and

cathode. 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 thought of 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

complicated behavior than this simple on

conducting electricity until a c

state in which the diode is said to be

biased diode varies only a little with the current, and is a function of temperature; this effect

can be used as a temperature sensor

Semiconductor diodes' nonlinear current

varying the semiconductor materials

These are exploited in special purpose diodes that perform many

example, diodes are used to regulate voltage (

voltage surges (avalanche diodes

diodes), to generate radio frequency

diodes), and to produce light (

resistance, which makes them useful in some types of circuits.

Diodes were the first semiconductor electronic devices

abilities was made by German physicist

diodes, called cat's whisker diodes

such as galena. Today most diodes are made of

germanium are sometimes used.

3.3.12 TRANSISTOR:

A transistor is a semiconductor device

and power. It is composed of a

connection to an external circuit. A voltage or current applied to one pair of the transistor's

terminals changes the current flowing through another pair of termi

PCE/EE/024

these diodes are forms of rectifiers. However, diodes can have more

complicated behavior than this simple on–off action. Semiconductor diodes do not begin

conducting electricity until a certain threshold voltage is present in the forward direction (a

state in which the diode is said to be forward-biased). The voltage drop across a forward

ased diode varies only a little with the current, and is a function of temperature; this effect

temperature sensor or voltage reference.

Fig 3.12 Diode

Semiconductor diodes' nonlinear current–voltage characteristic can be tailored by

semiconductor materials and introducing impurities into (doping

These are exploited in special purpose diodes that perform many different functions. For

example, diodes are used to regulate voltage (Zener diodes), to protect circuits from high

avalanche diodes), to electronically tune radio and TV receivers (

radio frequency oscillations (tunnel diodes, Gunn diodes

), and to produce light (light emitting diodes). Tunnel diodes exhibit

, which makes them useful in some types of circuits.

semiconductor electronic devices. The discovery of

abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor

cat's whisker diodes, developed around 1906, were made of mineral crystals

. Today most diodes are made of silicon, but other semiconductors

are sometimes used.

semiconductor device used to amplify and switch

and power. It is composed of a semiconductor material with at least three terminals for


terminals changes the current flowing through another pair of termi

However, diodes can have more

off action. Semiconductor diodes do not begin

ertain threshold voltage is present in the forward direction (a

). The voltage drop across a forward-

ased diode varies only a little with the current, and is a function of temperature; this effect

voltage characteristic can be tailored by

doping) the materials.

different functions. For

), to protect circuits from high

), to electronically tune radio and TV receivers (varactor

Gunn diodes, IMPATT

). Tunnel diodes exhibit negative

. The discovery of crystals' rectifying

in 1874. The first semiconductor

, developed around 1906, were made of mineral crystals

semiconductors such as

switch electronic signals

material with at least three terminals for


terminals changes the current flowing through another pair of terminals. Because the

PCE/EE/025

controlled (output) power can be higher than the controlling (input) power, a transistor can

amplify a signal.

Fig 3.13 Transistor

Today, some transistors are packaged individually, but many more are found

embedded in integrated circuits. The transistor is the fundamental building block of modern

electronic devices, and is ubiquitous in modern electronic systems. Following its

development in the early 1950s the transistor revolutionized the field of electronics, and

paved the way for smaller and cheaper radios, calculators, and computers, among other

things.

4.1 INTRODUCTION:

A seven-segment display (SSD), or sevendevice for displaying decimal numerals that is an alternative to the more complex dot matrix displays. Seven-segment displays are widely used in digital clocks, electronic meters, and other electronic devices for displaying numerical information.

Fig 4.1 A typical 7

4.2 HISTORY:

Seven-segment displays can be found in patents as early as 1908 (in U.S. Patent 974,943, F W Wood invented an 8-segment display, whichIn 1910, a seven-segment display illuminated by incandescent bulbs was used on a powerplant boiler room signal panel.[5] They did not achieve widespread use until the advent of LEDs in the 1970s. They are sometimes used in posters or tags, where the user either applies coloprinted segments, or applies color through a sevenfigures such as product prices or telephone numbers.For many applications, dot-matrix LCDs hain LCDs 7-segment displays are very common. Unlike LEDs, the shapes of elements in an LCD panel are arbitrary since they are formed on the display by a kind of printing process. In contrast, the shapes of LED they have to be physically moulded to shape, which makes it difficult to form more complex shapes than the segments of 7factor of 7-segment displays, and the comparatively high visual contrast obtained by such

PCE/EE/026

CHAPTER-4

Seven segment display

segment display (SSD), or seven-segment indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix

segment displays are widely used in digital clocks, electronic meters, and other displaying numerical information.

A typical 7-segment LED display component, with decimal point

segment displays can be found in patents as early as 1908 (in U.S. Patent 974,943, F segment display, which displayed the number 4 using a diagonal bar).

segment display illuminated by incandescent bulbs was used on a powerplant boiler room signal panel.[5] They did not achieve widespread use until the advent of

etimes used in posters or tags, where the user either applies coloprinted segments, or applies color through a seven-segment digit template, to compose figures such as product prices or telephone numbers.

matrix LCDs have largely superseded LED displays, though even segment displays are very common. Unlike LEDs, the shapes of elements in an

LCD panel are arbitrary since they are formed on the display by a kind of printing process. In segments tend to be simple rectangles, reflecting the fact that

they have to be physically moulded to shape, which makes it difficult to form more complex shapes than the segments of 7-segment displays. However, the high common recognition

ment displays, and the comparatively high visual contrast obtained by such

indicator, is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix

segment displays are widely used in digital clocks, electronic meters, and other

segment LED display component, with decimal point

segment displays can be found in patents as early as 1908 (in U.S. Patent 974,943, F displayed the number 4 using a diagonal bar).

segment display illuminated by incandescent bulbs was used on a power-plant boiler room signal panel.[5] They did not achieve widespread use until the advent of

etimes used in posters or tags, where the user either applies colour to pre-segment digit template, to compose

ve largely superseded LED displays, though even segment displays are very common. Unlike LEDs, the shapes of elements in an

LCD panel are arbitrary since they are formed on the display by a kind of printing process. In segments tend to be simple rectangles, reflecting the fact that

they have to be physically moulded to shape, which makes it difficult to form more complex segment displays. However, the high common recognition

ment displays, and the comparatively high visual contrast obtained by such

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displays relative to dot-matrix digits, makes seven-segment multiple-digit LCD screens very common on basic calculators. 4.3 CONCEPT AND VISUAL STRUCTURE:

The seven elements of the display can be lit in different combinations to represent the arabic numerals. Often the seven segments are arranged in an oblique (slanted) arrangement, which aids readability. In most applications, the seven segments are of nearly uniform shape and size (usually elongated hexagons, though trapezoids and rectangles can also be used), though in the case of adding machines, the vertical segments are longer and more oddly shaped at the ends in an effort to further enhance readability. The numerals 6, 7 and 9 may be represented by two or more different glyphs on seven-segment displays, with or without a 'tail'. The seven segments are arranged as a rectangle of two vertical segments on each side with one horizontal segment on the top, middle, and bottom. Additionally, the seventh segment bisects the rectangle horizontally. There are also fourteen-segment displays and sixteen-segment displays (for full alphanumerics); however, these have mostly been replaced by dot matrix displays. The segments of a 7-segment display are referred to by the letters A to G, where the optional DP decimal point (an "eighth segment") is used for the display of non-integer numbers. 4.4 IMPLEMENTATION:

Seven-segment displays may use a liquid crystal display (LCD), a light-emitting diode (LED) for each segment, or other light-generating or controlling techniques such as cold cathode gas discharge, vacuum fluorescent, incandescent filaments, and others. For gasoline price totems and other large signs, vane displays made up of electromagnetically flipped light-reflecting segments (or "vanes") are still commonly used. An alternative to the 7-segment display in the 1950s through the 1970s was the cold-cathode, neon-lamp-like nixie tube. Starting in 1970, RCA sold a display device known as the Numitron that used incandescent filaments arranged into a seven-segment display. In a simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected and brought out to a common pin; this is referred to as a "common cathode" or "common anode" device. Hence a 7 segment plus decimal point package will only require nine pins (though commercial products typically contain more pins, and/or spaces where pins would go, in order to match standard IC sockets. Integrated displays also exist, with single or multiple digits. Some of these integrated displays incorporate their own internal decoder, though most do not: each individual LED is brought out to a connecting pin as described. A multiplexed 4-digit, seven-segment clock display with only 12 pins Multiple-digit LED displays as used in pocket calculators and similar devices used multiplexed displays to reduce the number of I/O pins required to control the display. For example, all the anodes of the A segments of each digit position would be connected together and to a driver circuit pin, while the cathodes of all segments for each digit would be connected. To operate any particular segment of any digit, the controlling integrated circuit would turn on the cathode driver for the selected digit, and the anode drivers for the desired

segments; then after a short blanking interval the next digit would be selected and new segments lit, in a sequential fashion. In this manner an eight digit dsegments and a decimal point would require only 8 cathode drivers and 8 anode drivers, instead of sixty-four drivers and IC pins.[4] Often in pocket calculators the digit drive lines would be used to scan the keyboard as well, providing fmultiple keys at once would produce odd results on the multiplexed display.can encode the full state of a 7and abcdefg, where each letter represenrepresentation, a byte value of 0x06 would (in a commonand 'b', which would display a '1'.

4.5 DISPLAYING LETTERS:

Hexadecimal digits can be displayed on uppercase and lowercase letters are used for Aunambiguous shape for each letter (otherwise, a capital D would look identical to an 0 and a capital B would look identical to an 8). Also the digit 6 must be displayed with the top bar lit to avoid ambiguity with the letter b

Table 4.1 Hexadecimal encoding for displaying the digits 0 to F

PCE/EE/028

segments; then after a short blanking interval the next digit would be selected and new segments lit, in a sequential fashion. In this manner an eight digit dsegments and a decimal point would require only 8 cathode drivers and 8 anode drivers,

four drivers and IC pins.[4] Often in pocket calculators the digit drive lines would be used to scan the keyboard as well, providing further savings; however, pressing multiple keys at once would produce odd results on the multiplexed display.can encode the full state of a 7-segment-display. The most popular bit encodings are gfedcba and abcdefg, where each letter represents a particular segment in the display. In the gfedcba representation, a byte value of 0x06 would (in a common-anode circuit) turn on segments 'c' and 'b', which would display a '1'.

ISPLAYING LETTERS:

Hexadecimal digits can be displayed on seven-segment displays. A particular combination of uppercase and lowercase letters are used for A–F; this is done to obtain a unique, unambiguous shape for each letter (otherwise, a capital D would look identical to an 0 and a

al to an 8). Also the digit 6 must be displayed with the top bar lit to avoid ambiguity with the letter b.

Hexadecimal encoding for displaying the digits 0 to F

segments; then after a short blanking interval the next digit would be selected and new segments lit, in a sequential fashion. In this manner an eight digit display with seven segments and a decimal point would require only 8 cathode drivers and 8 anode drivers,

four drivers and IC pins.[4] Often in pocket calculators the digit drive lines urther savings; however, pressing

multiple keys at once would produce odd results on the multiplexed display. A single byte display. The most popular bit encodings are gfedcba

ts a particular segment in the display. In the gfedcba anode circuit) turn on segments 'c'

segment displays. A particular combination of F; this is done to obtain a unique,

unambiguous shape for each letter (otherwise, a capital D would look identical to an 0 and a al to an 8). Also the digit 6 must be displayed with the top bar lit

PCE/EE/029

CHAPTER 5

PCB DESINGING

5.1. PRINTED CIRCUIT BOARD A printed circuit board, or PCB, is used to mechanically support and electrically connect

electronic components using conductive pathways, tracks, or traces, etched from copper

sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board

(PWB) or etched wiring board. A PCB populated with electronic components is a printed

circuit assembly (PCA), also known as a printed circuit board assembly (PCBA).

Fig 5.1 Copper PCB

PCBs are inexpensive, and can be highly reliable. They require much more layout effort and

higher initial cost than either wire-wrapped or point-to-point constructed circuits, but are

much cheaper and faster for high-volume production. Much of the electronics industry's PCB

design, assembly, and quality control needs are set by standards that are published by the IPC

organization. Conducting layers are typically made of thin copper foil. Insulating layers

dielectric is typically laminated together with epoxy resin prepregnated . The board is

typically coated with a solder mask that is green in color. Other colors that are normally

available are blue and red. There are quite a few different dielectrics that can be chosen to

provide different insulating values depending on the requirements of the circuit. Some of

these dielectrics are poly tetra fluoroethylene (Teflon), FR-4, FR-1, CEM-1 or CEM-3. Well

known prepregnated materials used in the PCB industry are FR-2 (Phenolic cotton paper),

FR-3 (Cotton paper and epoxy), FR-4 (Woven glass and epoxy), FR-5 (Woven glass and

epoxy), FR-6 (Matte glass and

paper and epoxy), CEM-2 (Cotton paper and epoxy), CEM

CEM-4 (Woven glass and epoxy), CEM

is an important consideration espe

fiber offers the best dimensional stability. In some PCB the lamination are also uses so the

possibility of error is minimize.

`For the PCB layout we required dip trace software. In the dip trace softwa

component are available, so according to requirement we use the component are form the

desire circuit with the help of these components.

After the formation of desire circuit we used the run command and now all the components

are place at appropriate place and connection are shown in given accurate place. After

designing of PCB layout on the software we required take printout of it as shown in figure.

Now this circuit is superimposed on the PCB so that this circuit is completely drawn on PCB.

Now PCB is placed in the solution of the KOH so that all the unwanted copper is removed.

After 35min the PCB is take out from the solution and now PCB designing is completed.

Fig 5.2. PCB

PCE/EE/030

6 (Matte glass and polyester), G-10 (Woven glass and epoxy), CEM

2 (Cotton paper and epoxy), CEM-3 (Woven glass and epoxy),

4 (Woven glass and epoxy), CEM-5 (Woven glass and polyester). Thermal expansion

is an important consideration especially with BGA and naked die technologies, and glass


possibility of error is minimize.

For the PCB layout we required dip trace software. In the dip trace softwa


desire circuit with the help of these components.


riate place and connection are shown in given accurate place. After



PCB is placed in the solution of the KOH so that all the unwanted copper is removed.


5.2. PCB for variable power supply with digital control

10 (Woven glass and epoxy), CEM-1 (Cotton

3 (Woven glass and epoxy),

5 (Woven glass and polyester). Thermal expansion

cially with BGA and naked die technologies, and glass


For the PCB layout we required dip trace software. In the dip trace software all the



riate place and connection are shown in given accurate place. After



PCB is placed in the solution of the KOH so that all the unwanted copper is removed.


PCE/EE/031

CHAPTER 6

SOLDERING OF COMPONENT

6.1 INTRODUCTION

Soldering is the process of a making a sound electrical and mechanical joint between certain

metals by joining them with a soft solder. This is a low temperature melting point alloy of

lead and tin. The joint is heated to the correct temperature by soldering iron. For most

electronic work miniature mains powered soldering irons are used. These consist of a handle

onto which is mounted the heating element. On the end of the heating element is what is

known as the "bit", so called because it is the bit that heats the joint up. Solder melts at

around 190 degrees Centigrade, and the bit reaches a temperature of over 250 degrees

Centigrade. This temperature is plenty hot enough to inflict a nasty burn, consequently care

should be taken.

It is also easy to burn through the PVC insulation on the soldering iron lead if you were to lay

the hot bit on it. It is prudent, therefore, to use a specially designed soldering iron stand.

These usually incorporate a sponge for keeping the bit clean. Soldering irons come with

various ratings from 15W to over 100W. The advantage of a high wattage iron is that heat

can flow quickly into a joint, so it can be rapidly made. This is important when soldering

connectors as often there is a quite a large volume of metal to be heated. A smaller iron

would take a longer time to heat the joint up to the correct temperature, during which time

there is a danger of the insulation becoming damaged. A small iron is used to make joints

with small electronic components which are easily damaged by excess heat.

Always use a good quality multi core solder. A standard 60% tin, 40% lead alloy solder with

cores of non-corrosive flux will be found easiest to use. The flux contained in the longitudinal

cores of multi core solder is a chemical designed to clean the surfaces to be joined of

deposited oxides, and to exclude air during the soldering process, which would otherwise

prevent these metals coming together. Consequently, don't expect to be able to complete a

joint by using the application of the tip of the iron loaded with molten solder alone, as this

usually will not work. There is a process called tinning where conductors are first coated in

fresh, new solder prior to joining by a hot iron. Solder comes in gauges like wire. The two

commonest are 18 SWG, used for general work, and the thinner 22 SWG, used for fine work

on printed circuit boards.

PCE/EE/032

6.2 SOLDERING TOOLS

Different soldering jobs will need different tools and different temperatures too. For circuit

board work you will need a finer tip, a lower temperature and finer grade solder. You may

also want to use a magnifying glass. Audio connectors such as XLR's will require a larger tip,

higher temperature and thicker solder. Clamps and holders are also handy when soldering

audio cables.

6.2.1 SOLDERING IRON

There are several things to consider when choosing a soldering iron.

1. Wattage

2. adjustable or fixed temperature

3. power source (electric or gas)

4. portable or bench use

Fig. 6.1 Soldering Iron

6.2.2 SOLDER WIRE

The most commonly used type of solder is rosin core. The rosin is flux, which cleans as you

solder. The other type of solder is acid core and unless you are experienced at soldering, you

should stick to rosin core solder. Acid core solder can be tricky and better avoided for the

beginner. Rosin core solder comes in three main types - 50/50, 60/40 and 63/37. These

numbers represent the amount of tin and lead are present in the solder, as shown below.

Table 6.1: Types Of Solder Wire

PCE/EE/033

Solder Type % Tin % Lead Melting Temp (°F)

50/50 50 50 425

60/40 60 40 371

63/37 63 37 361

6.2.3 FLUX

In metallurgy, a flux is a chemical cleaning agent which facilitates soldering, brazing, and

welding by removing oxidation from the metals to be joined. Common fluxes are: ammonium

chloride or rosin for soldering tin; hydrochloric acid and zinc chloride for soldering

galvanized iron (and other zinc surfaces); and borax for brazing or braze-welding ferrous

metals. Different fluxes, mostly based on sodium chloride, potassium chloride, and a fluoride

such as sodium fluoride, are used in foundries for removing impurities from molten

nonferrous metals such as aluminium, or for adding desirable trace elements such as titanium.

PCE/EE/034

CHAPTER 7

RESULT AND APPLICATION

7.1 RESULT: The voltage varied by different values of variable resistors are tabulated as

shown below:

Resistance Value (in Ohm)

O/P Voltage (in volts)

200K 1.0 200K 1.5 200K 2.0 200K 3.0 200K 5.0 200K 7.0 200K 9.0 200K 10.0 200K 12.0

Table 7.1: Results for variable resistors

7.3 APPLICATION:

1. Variable power supply through variable resistors is more reliable.

2. Variable power supply with digital control with seven segments output delivers great user

friendly also.

3. The same circuit finds its application to control the level of the voltages.

4. This circuit also finds its application for RF power amplifier.

7.4 ADVANTAGES

� This circuit is simple to use and efficient.

� It can be assembled with ease.

� It is cost effective and hence very economical.

� It is compact in size.

� It is efficient enough for displaying the voltage values.

PCE/EE/035

CONCLUSION

Variable Power Supply with Digital Control with seven segments display is one of the

applications of electronics to increase the facilities of life. And it is the most frequently used

device in electronic workshops and laboratories is a universal power supply that provides a

variable, fluctuation-free output.

With the knowledge of new techniques in ‘Electronics’ we are able to make our life more

comfortable. One such application of electronics is used in “RF power amplifier”.RF power

amplifiers can save much energy if they are supplied with a variable voltage as described in

the state of the art. The design of the power supply of these amplifiers is challenging since

many requirements have to be accomplished: very low output voltage ripple; wide output

voltage variation at kHz frequencies; fast load current steps; etc. A typical solution is the use

of a multiphase dc-dc converter based on the buck topology. In this paper, we propose the use

of digital control for these power supplies. The main advantage is that current loops are

removed. The design of this control circuit and main trade-offs are discussed. The results

obtained from a 240 W prototype show the advantages and the limitations of this proposal.

PCE/EE/036

REFERENCE

1. http://en.wikipedia.org/wiki/sevensegmentsdisplay 2. http://en.wikipedia.org/wiki/trasister 3. http://www.datasheetarchive.com/wireless%20speed%20control%20of%

20single%20phase%20induction-datasheet.html 4. http://en.wikipedia.org/wiki/LM7809 5. http://en.wikipedia.org/wiki/LM317 6. http://en.wikipedia.org/wiki/CD4017 7. http://en.wikipedia.org/wiki/NE555 8. http://en.wikipedia.org/wiki/LM79LXX

1. Electronic Devices and Circuits – J. B.Gupta 2. Linear Integrated circuits – Gayakwad 3. Power electronics – Md.Rashid

variable power supply with digital control with seven segments display

Engineering

prashant jain

digital control

project stage

degree of bachelor

award of bachelor

om prakash sharma principal

segments displaypritam

partial fulfilment