KATHMANDU UNIVERSITY SCHOOL OF ENGINEERING

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING

PROJECT REPORT

Design and Construction of a Path Detector

by: Sujeet Kumar Jha(12009)

Manish Karn(12035) Ahmed Raja Khan(12432)

July 2014

CERTIFICATION

FIRST YEAR PROJECT REPORT

on

Design and Construction of a Path Detector

by:

Sujeet Kumar Jha(12009)

Manish Karn(12035)

Ahmed Raja Khan(12432)

Approved by: 1. Project Supervisor ___________________ ____________________________ __________

(Signature) (Name) (Date) 2. Head/In-Charge of the Department ___________________ ____________________________ __________

(Signature) (Name) (Date)

TABLE OF CONTENTS

Abstract i Acknowledgement ii Symbols and Abbreviations iii List of Figures iii List of Tables iii Chapter 1: Introduction 1

1.1 Background and Objectives 1 1.2 System overview 1 1.3 Schematic Parts References 1 1.4 The Theory 1

Chapter 2: Technology and Literature Survey 1. 555 Timer 3 2. Light Dependent Resistor 3 3. Comparator 4 4. AND Gate 4 5. Buzzer 5 6. LED 5

Chapter 3: Product Description and Performance 6 3.1 Product Decription 6 3.2 Performance 7 Chapter 4: Discussion and Conclusion 8 GANTT CHART 9 Bibliography 10 Appendix A: Datasheets of Components

i

ABSTRACT

Students from first year mainly belonging to Electrical and Electronics department are unknown about the practical use of electrical components their types and identification, how electrical circuits works, how to implement theoretical electrical laws (ohm’s law, Superposition law, Norton’s theorems etc.), assembling of the components. In order to achieve these problems, electrical projects will help to provide exact solution to the concerned problem. Our project is to build a device that can sense the difference between black and white path. We have used timer, comparator and AND gate as main components in our project. For our device black path will be the correct path. If the device is partially in black and partially in white path then LED is used as the indicator and if our device is fully in white path then LED blinks along with buzzer which gives audible voice which indicates whole device is in wrong path. We have tried our best to complete our project in time.

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ACKNOWLEDGEMENT We would like to thank Department of Electrical and Electronics to provide us the opportunity to work on this project which will help us to explore our creativity and knowledge. We would also like to thank our Project Coordinator Mr. Subodh Ghimire for his guidance and time to guide us throughout the project.

At last we would like to acknowledge our colleague and seniors at Kathmandu University, for giving their valuable suggestion and technical help to complete the recommended proposal.

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SYMBOLS AND ABBREVIATIONS A. Symbols Symbol Description First Used in Page K Kilo-Ohm 1

B. Abbreviations Abbreviation Full Form First Used in Page LED: Light Emitting Diode 1 LDR: Light Dependent Resistor 1

LIST OF FIGURES Fig. No. Title Page No. 1. PCB Board Overview 2 2. Breadboard Circuit Arrangement 2 3. NE555 Circuit Configuration And Output 3 4. LDR 3 5. LM324N Circuit Configuration 4 6. MC74F08 Circuit Configuration 4 7. Buzzer 5 8. LED 5.

LIST OF TABLES Table No. Title Page No. 1 Schematic Parts Reference 1.

1

CHAPTER 1

INTRODUCTION

1.1 Background and Objectives The purpose of this project is to build a device that can sense the difference between

black and white paths so that the path detector can follow a black line on a sheet of white

paper. This device will be low cost. It will also be able to follow straight and curvy lines

alike. A path detector is a simple device that detects and follows a black line drawn on a

white surface. The control system used must sense the line and maneuver the device to

stay on course while constantly correcting the wrong moves using feedback mechanism.

1.2 System Overview The schematic has three main components. They are NE555 Timer, Comparator

(LM324N) and AND gate (MC74F08).

1.3 Schematic Parts References

S.No Name Quantity Description 1 Breadboard 1 2 Resistor 6 1K,480K,1.2K,1.5K 3 Capacitor 1 1000 micro-farad 4 Potentiometer 2 100 K 5 LED 3 6 Timer 1 NE555 7 Comparator 1 LM324N 8 AND Gate 1 MC74F08 9 LDR 1

1.4 The Theory

The theory of this project is based upon mainly three components as explained earlier.

The LED send outs visible light and the LDR receives visible light from the reflected

surface. As we know that white will reflect all colors while black will absorb them. So

when the LED emits visible light onto white surface, the LDR receives the reflected light

and sends a voltage signal to LED1 and LED1 blinks as the result. When light is

reflected off of black surface, light is not reflected and LDR doesn’t receive any light as

the result LED1 is turned off. Also same working mechanism occurs in the case of

LED2. In summarized way when one wheel of the path detector is in white part LED1 or

LED2 blinks as per condition given but when whole of the path detector is in white path

LED blinks and buzzer give audible sound as indicator for path detector being in wrong

path.

2

PCB Board Overview

Breadboard Circuit Arrangement

3

CHAPTER 2

TECHNOLOGY AND LITERATURE SURVEY

2.1 Literature Survey

Following are the details of the components that we are going to use in our project.

1. 555 Timer (NE555):

The 555 timer is IC is an integrated circuit used in a variety of time, pulse generation

and oscillator application. The 555 can be used to provide time delays as an

oscillator. In our project NE555 Timer is made to work in an astable mode.

An astable circuit has no stable state - hence the name "astable". The output

continually switches state between high and low without any intervention from the

user, called a 'square' wave. This type of circuit could be used to give a mechanism

intermittent motion by switching on and off at regular intervals. It is used to blink

LEDs.

Fig.a. Astable circuit in NE555 timer Fig.b. Output (pin 3)

2. Light Dependent Resistor (LDR):

It is the electronics component where the resistance of device varies with light

intensity. It is also called as LDRs, photoresistors or photoconductors. It is used to

detect the presence of light. Normally the resistance of LDR is very high(1 Mega-

Ohm). When illuminated with light resistance drops dramatically.

Fig. Light Dependent Resistor

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3. Comparator (LM324N):

LM324 is a 14 pins IC consisting of four independent operational amplifiers (op-

amps) compensated in a single package. They can be used as amplifiers, comparators,

oscillators, rectifiers, etc. It compares two voltage signals and determines which one

is greater.

Fig.a. Circuit configuration Fig.b. Comparator

4. AND Gate (MC74F08)

The symbol for a 2-input AND gate looks like this:

Input voltages can be LOW, logic 0, or HIGH, logic 1,

Fig.a.. AND Gate(MC74F08) Fig.b. circuit configuration

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5. Buzzer

A buzzer is an audio signaling device. It includes confirmation of user input.

Fig. Buzzer

6. LED

A light-emitting diode (LED) is a two-lead semiconductor light source. It resembles a

basic pn-junction diode, which emits light when activated.

Fig. LED

7. Potentiometer

A potentiometer is an instrument for measuring the potential (voltage) in a circuit.

We used potentiometer as variable resistor.

Fig. Potentiometer

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CHAPTER 3

PRODUCT DESCRIPTION AND PERFORMANCE

3.1 Product Description

The product is the assembling of the three major electronics circuits in order to get desired

output.

Astable mode of NE555 timer IC

Using LM342N OP-AMP gain

MC74F08 IC as AND gate

Here the dc voltage of + 5V (VCC) is obtained from the cell of 9V by using resistance

voltage drop method. The astable mode of NE555 timer IC is connected to vcc and ground in

the respective pin. The output from pin 3 is fluctuating voltage that imparts the blinking

action LED, utilized for the input for the LDR1 and LDR2.

The both LDR is further connected with respective POTS (100k) which act as voltage

divider. The voltages drop between them is used as inverting voltage. The voltage drop

between the series combination of two resistors (1.2 K and 1.5 K) is used for the non-

inverting (reference voltages). The both voltages are connected to the LM342N respective

pin.

The output is obtained from the OP-AMP is utilised for the left end LED and right end Led.

The outputs is used in inputs for the AND gate which output is again used in tuning buzzer.

Fig . Electronics circuit of the path detector product.

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3.2 Performance

Here the black surface is consider as right path and white surface is consider as wrong

path. The path detector light sensor module consists of light sensor (LDR) and light

emiiter( LED) .The emitter will throw light on the floor, whose reflection will then be

picked up by the LDR.

If the path is black, most of the light thrown will be absorbed and very little light will

be received by the sensors. In this case warning LED doesn’t not blink.

If the path underneath the sensor is white, most of the light thrown by the emitter will

be reflected and received by the sensor. This will increase the voltage flow to

comparator and the stage at which the voltage cross the reference voltage and and

voltage supplies to led( blinks) and input for AND gate.

If the right end of the model is deviates towards white path the led at right most end

will blinks. If the left end of the model is deviates towards white path the led at left

most end will blinks. If the whole model is in wrong path both LEDs will blink

accompany warning tone of buzzer. The tuning of buzzer is obtained by and AND

gate.

Fig. The illustration showing the phenomenon of sensor in white and black path.

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CHAPTER 4

DISCUSSION AND CONCLUSION

5.1 Discussion

Being new to electrical and electronics tools, it was very difficult to be familiar with the

electrical and electronics devices and its working mechanism. A majority of the time was

spent on understanding and developing concepts regarding use of breadboard, circuit

configuration of timer, comparator and gates with the help of different books and online

tutorials. After that we started developing ideas to make path detector. In the mean time

we faced different errors in our project which was solved through supervision of our

supervisor and different online forums.

5.2 Conclusion

Path Detector was designed and developed within the period of 14 weeks. The

development of this project arose from an idea of developing a project of Line Following

Robot. The task of designing and developing and upgrading this project is ever going

process.

With respect to allocated time, this path detector has been developed to the fullest level

possible. The path detector can be used now to detect white and black path.

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GANTT CHART

March April May June July

Proposal and presentation Bread board circuit arrangement

Testing and Verification Design in PCB Modeling of Path Detector Assembling, Testing and presenting of Path Detector

Work Completed Work Remaining

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BIBLIOGRAPHY

1. B.L THERAJA, Basic Electronics Solid State, S.CHAND & COMPANY LTD., 2005 2. http://www.instructables.com 3. http://www.instructables.com/id/Flashing-LED-using-555-Timer/ 4. http://www.instructables.com/id/Wire-a-Potentiometer-as-a-Variable-Resistor/ 5. http://www.engineersgarage.com/electronic-components/lm324n

Appendix A: Components

1. Datasheet on NE555 Timer

Features

High Currrent Drive Capability(200mA)

Adjustable Duty Cycle

Temperature Stability of 0.005%/degree Celsius

Timing From µSec to Hours

Turn off Time Less than 2µSec

Applications

Precision Timing

Pulse Generation

Time Delay Generation

Sequential Timing

Description

The NE555 Timer is a highly stable controller capable of producing accurate timing

pulses. With a monostable operation, the time delay is controlled by one external

resistor and one capacitor. With a monostable operation , the time delay is controlled

by one external resistor and one capacitor. With an anstable operation , the frequency

and duty cycle are accurately controlled by two external resistors and one capacitor.

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Fig. NE555 Timer

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NE555 Astable mode

In astable mode, the 555 timer puts out a continuous stream of rectangular pulses having a

specified frequency. Resistor R1 is connected between VCC and the discharge pin (pin 7) and

another resistor (R2) is connected between the discharge pin (pin 7), and the trigger (pin 2)

and threshold (pin 6) pins that share a common node. Hence the capacitor is charged through

R1 and R2, and discharged only through R2, since pin 7 has low impedance to ground during

output low intervals of the cycle, therefore discharging the capacitor.

In the astable mode, the frequency of the pulse stream depends on the values of R1, R2 and C:

[7]

The high time from each pulse is given by:

and the low time from each pulse is given by:

where R1 and R2 are the values of the resistors in ohms and C is the value of the capacitor

in farads.

The power capability of R1 must be greater than .

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2. Datasheet on LM324

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15

3. Datasheet on MC74F08

Arrangement inside MC74F08 (QUAD 2-INPUT AND GATE)

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Operating Ranges

DC characteristics over operating temperature ranges (unless otherwise

specified)

AC characteristics

Datasheet on NE555 Timer

Features

High Currrent Drive Capability(200mA)

Adjustable Duty Cycle

Temperature Stability of 0.005%/degree Celsius

Timing From µSec to Hours

Turn off Time Less than 2µSec

Applications

Precision Timing

Pulse Generation

Time Delay Generation

Sequential Timing

Description

The NE555 Timer is a highly stable controller capable of producing accurate timing pulses.

With a monostable operation, the time delay is controlled by one external resistor and one

capacitor. With a monostable operation , the time delay is controlled by one external resistor

and one capacitor. With an anstable operation , the frequency and duty cycle are accurately

controlled by two external resistors and one capacitor.

Fig. NE555 Timer

NE555 Astable mode

In astable mode, the 555 timer puts out a continuous stream of rectangular pulses having a

specified frequency. Resistor R1 is connected between VCC and the discharge pin (pin 7) and

another resistor (R2) is connected between the discharge pin (pin 7), and the trigger (pin 2) and

threshold (pin 6) pins that share a common node. Hence the capacitor is charged through R1 and

R2, and discharged only through R2, since pin 7 has low impedance to ground during output low

intervals of the cycle, therefore discharging the capacitor.

In the astable mode, the frequency of the pulse stream depends on the values of R1, R2 and C:

[7]

The high time from each pulse is given by:

and the low time from each pulse is given by:

where R1 and R2 are the values of the resistors in ohms and C is the value of the capacitor

in farads.

The power capability of R1 must be greater than .

Datasheet on LM324

Datasheet on MC74F08

Arrangement inside MC74F08 (QUAD 2-INPUT AND GATE)

Operating Ranges

DC characteristics over operating temperature ranges (unless otherwise specified)

AC characteristics