Design and Construction of a Tele-Remote System

7/29/2019 Design and Construction of a Tele-Remote System

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REGENT UNIVERSITY COLLEGE OF SCIENCE AND

TECHNOLOGY

Design and Construction of a Tele- Remote System to control sliding

windows

PRESENTED BY

Atanga, Azaare Francis

ID: 1960108

DISSERTATION SUBMITTED TO THE SCHOOL OF INFORMATICS

AND ENGINEERING, REGENT UNIVERSITY COLLEGE OF SCIENCE

AND TECHNOLOGY, IN PARTIAL FULFILLMENT OF THE

REQUIREMENT FOR THE AWARD OF BACHELOR OF ENGINEERING

DEGREE IN ELECTRONICS AND SYSTEMS ENGINEERING

(TELECOMMUNICATION OPTION)

SEPTEMBER, 2011


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DECLARATION

This dissertation has not previously been accepted in substance for a degree or being

concurrently submitted in candidature for any degree.

This dissertation is a result of my investigations except otherwise stated. All sources used in the

production of this dissertation are acknowledged by appropriate citation and explicit references

and are included in the bibliography that is appended.

I give my consent for this dissertation, if accepted, to be available for photocopying and for inter-

library loan, and for the title and summary to be made available to organizations external to

Regent University College of Science and Technology.

....

Students Signature Date

(Atanga, Azaare Francis)

This dissertation is submitted for examination with the full knowledge and acceptance of my

supervisor.

.

Supervisors signature Date

(Mr. Emmanuel A. Williams)


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ABSTRACT

Telecommunication and Electronics technologies have advanced to such a stage where it

became possible to remotely close slide windows or doors of your house or office. Thus, this

project has demonstrated beyond all reasonable doubts that, it is not only nearness to the

controlled system that remote control operations can be possible, but also, when millions of

miles away from home or office. The embedded DTMF receiver (MT8870) was utilized in

connection with a personal mobile phone, a clock circuit, a decoder system and a stepper motor

with pulley system, to make the idea a success. Interestingly, remote control systems have

graduated from infrared technology through radio to telephone remote control systems. The

method through which the Tele-remote system was designed and constructed was put in simple

terms such that anyone who has basic understanding of electronics can reproduce this project.

The circuit design was systematically put together by the aid of a computerized software system

known as Circuit Maker version 5.Testing the system has been explained in the results and

findings of which the system closes slide windows and doors but could not open them. It was

concluded that the main objective of using telephone to remotely close slide doors and windows

was achieved. Recommendations were then given for further research and advancement in the

circuitry to enable using the system to open the slide doors and windows as well.


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ACKNOWLEDGEMENT

My sincere gratitude first of all goes to the Almighty God for seeing me through this research

successfully. Lord, thank you. Secondly, I cannot forget the fact that there is this special brother

of mine who assisted me financially when things got tough for me along the way. He is no other

than Rexford Anaba Atanga. I appreciate you.

Then also, there are a special number of people who gave tremendous support and

encouragement during my research: I must say thank you to John Aquah-Carrie for making

available to me his electronics shop, tools and equipments.

My special thanks goes also to my supervisor, Mr. Emmanuel A. Williams, he has been like a

father to me. You guided me throughout my write up. You assisted me to address many

mistakes. I cannot forget that the School of Informatics and Engineering did me some blessing. I

say thank you to my Head of Department and the Dean.

Last but not the least, I will like to extend my gratification to my wife Rita, thank you for your

encouragement and love during my sleepless nights. Thank you.


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DEDICATION

I dedicate this project to the only Living God for He has done everything for this project to

become a reality.


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DECLARATION..i

ABSTRACT.ii

ACKNOWLEDGEMENT...iii

DEDICATION.....iv

TABLE OF CONTENTSPAGES

1.0 CHAPTER ONE - INTRODUCTION.......... .........1

1.1. Background.....1

1.2. Statement of Problem..........2

1.3. Objective.............3

1.4. Scope of Study........3

1.5. Significance of Study..........3

1.6. Limitation........3

2.0. CHAPTER TWO - LITERATURE REVIEW......5

2.1. Introduction.........5

2.2. Existing Projects......................5

2.2.1. Television Remote Control......5

2.2.2 Voice Operated Remote Control ..6

2.2.3 Opto-Components.........7

2.2.4 Consumer Electronics....8

2.2.5 Principles of Infrared Operation....8

2.2.6. Radio Remote Control..9


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2.2.7. Opto-Coupler..10

2.3. The 555 Timer....11

2.4. Operational Amplifier........14

2.4.1 Operational Amplifier Parameters.......16

2.5. The Transistor as a Switch: ...17

2.7. The LM317 Adjustable Voltage Regulator:...........22

2.8. Logic Gate......23

2.8.1. NAND Gate .......23

2.8.2 The JK Flip flop.......23

2.9. Stepper Motor..25

2.9. Dual Tone Multi-Frequency.......26

2.9.1 Resistors.......27

2.9.2 Resistor Colour Code......28

3.0 CHAPTER THREE- METHODOLOGY.....29

3.1. Introduction.......29

3.2. Components used forThe Project.............29

3.3 Tools for the Project .... .............31

3.4. Methods....32

3.4.1. Designing the Complete Circuit Diagram............32

3.4.2. Testing the Opto-coupler...33

3.4.3 One Shot Monostable Flipflop...34

3.4.4. Switching Relay with a Transistor Switch........35


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3.4.5. Transfer of Design to the PCB...35

4.0. CHAPTER FOUR: SYSTEM DESIGN, DEVELOPMENT AND

IMPLEMENTATION36

4.1. System Design.......36

4.2. Block Diagram of Tele-remote System..........36

4.2.1. Design Calculations.....36

4.2.2 .Complete Circuit of the Project..40

.4.3. Development and implementation.........41

4.3.1. Stages of Development...................41

5.0.CHAPTER FIVE - RESULTS AND DISCUSSION.....48

5.1 Results......48

5.2 Cost Analysis ..48

5.2.1 Material Cost.48

5.2.2 Labour Cost..........50

5.2.3 Overhead Charge..........50

5.3 Discussion51

6.0 CHAPTER SIXCONCLUSION AND RECOMMENDATION......52

6.1 Conclusion.............. 52

6.2 Recommendation.................52

References.............54

Glossary.............56

List of Figures................58

ListofTables.. .60


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CHAPTER ONE

1.0 INTRODUCTION

1.1. Background of the study

Remote control systems were formerly designed to control remote systems in a very short

range. Thus, Infrared, Bluetooth and Radio technologies have been of great importance when it

comes to controls within short distances. Modern electronics has made it possible to control

remote systems over wide range. The advent of modern telecommunication infrastructure has

made it possible for remote systems to be controlled where ever in the world. Thus overcoming

the limited range offered by Infrared, Bluetooth and Radio technologies.

The purpose of this design and construction of tele-remote control system to close sliding

windows via mobile phone is to enable busy people to be able to close sliding windows when

they are away from home. The system consists of a personal mobile phone of the user and the

remote system installed in the residence of the user. The remote system has an entrenched mobile

phone that receives command codes from the personal mobile phone of the user. An MTN

customized mobile phone was used for the sake of this project.

The user will dial the mobile number of the mobile phone embedded in the system and the

system will respond automatically. As it responds, the user will notice active on the screen of his

personal mobile phone, and then he or she will start issuing command codes from his or her

keypad of the phone.

The prototype was designed to receive command codes from the number 2 of the phone

keypad. Pressing the digit 2 will cause the slide window to close.


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A limit switch generates a feedback in the form of a tone to inform user that the slide window or

door has been completely closed.

This system will be a convenient system for busy people whose daily schedules are very tight

and always late for home.

It is however important to note that due to financial difficulties in providing a number of sliding

windows, the prototype has only one sliding window available.

1.2 Statement of Problem

Human beings as dynamic thinking creatures always strive to make life some-what easy. If

one is in the house he or she can open and close slide windows manually or by the use of the

remote controls that depend on close proximity to function properly. If one happened to move

out of the house to a distant place where the infrared, Bluetooth and radio remote controls have

become helpless and then he remembers he or she did not close the sliding windows; supposing

that, it is even threatening to rain, and the case is that; no one can also enter your house to close

the windows since the main door to the house had been locked. How can you close your

windows? Does one resort to prayers so that the rain stops? Or one just have to let the storm

destroy things in the house? This is a serious problem that requires an innovative solution. Now,

the proposed control system that uses the telecommunication finds this solution. The question

however is:

Can this system really be able to close a slide door or window? Will this system work the same with different kinds of mobile phones?


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1.3 Objectives

The main aim of this project is to design and subsequently construct an operational teleremote

control system that can control sliding windows. The system should be able

To close the slide windows easily. To work successfully with all kinds of mobile phones .i.e. different mobile networks.

1.4. Scope of study

The study is to construct the telephone remote control system to close sliding windows. It must

come with a feedback to indicate the complete closure of the door or window.

The areas of opto-electronics such as opto couplers, light emitting diodes, photo-transistors,

flip-flops, operational amplifiers, logic gates and 555 timers, tackling the various aspects of the

timer circuits. Multiplexers and decoders have not been left out.

A little touch on telecommunication is on the Dual Multi-Frequency Tone (DTMF).

1.5 Significance of Study

The Tele-remote System will play a very important role in society. Busy people who can easily

forget to close up their sliding windows can now do so while at a distant place. This prevents

rain water from destroying properties inside their houses when they forgot to close their sliding

windows.

1.6. Limitation of the study

The first limiting factor to this study has to do with finance. Everything revolving around this

project involves money: Money for transportation to go round for data, money to search for


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information from the internet, money for the purchase of instruments and money to purchase

components to build the prototype.

Lack of access to components becomes another limitation as far as this project was concerned.

The principal components such as MT 8870, the piezoelectric-crystal, 74LS122, and some of the

regulators were imported from China at a very expensive price due to Shipment cost.

It must also be made clear that time was another limiting factor; the project could have

been modeled with more advanced circuitry to take care of other functions like setting a security

password, tamper facility, and lockout facility. Adding this circuitry would have required a little

longer time.


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CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 Introduction

This chapter looks deep into the revolution of remote control systems, beginning from infrared

technology, through Bluetooth to radio and to voice operated remote control systems. Important

theories that are relevant for the research and building of the project have also been studied.

2.2. Existing projects

2.2.1. Television remote control

The history of remote control systems were developed since the 1898, when Nikola Tesla made

one and named it ,U.S. Patent 613,809, Method of an Apparatus for Controlling Mechanism of

Moving Vehicle or Vehicles. In 1898, he presented a radio-controlled boat to the public during an

electrical exhibition at Madison Square Garden. Tesla called his boat a "teleautomaton [1]

A remote control, according to Wikipedia, is a component of an electronics device, which was

originally meant for a television set, used for operating the television device wirelessly from a

short line-of-sight distance. The remote control can be considered as a kind of controller. It is

known by many other names as well, such as converter, clicker, "The box" didge, flipper, the

tuner, the changer, or the button. Usually, remote controls are Consumer IR devices performing

the function of issuing commands from a distance to televisions or other consumer electronics.

An example of such consumer electronics are stereo systems, DVD players and dimmers.

Remote controls for these devices are usually small wireless handheld objects with a matrix of

buttons for setting various channels of television sets, track number, and volume. It was clear

that, for the majority of modern devices with this kind of control, the remote contains all the

function controls while the controlled device itself only has a handful of essential primary

controls. These remotes always almost communicate through infrared (IR) signals and a few use

radio signals for their transmission. Earlier remote controls in the 1970s made use of ultrasonic


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tones. Television IR signals can be mimicked by a universal remote, which is able to emulate the

functionality of most major brand television remote controls. They are usually powered by small

A23 size batteries.

In 1903, Leonardo Torres Quevedo presented the Telekino at the Paris Academy of Science,

accompanied by a brief, and making an experimental demonstration. In the same time he

obtained a patent in France, Spain, Great Britain, and the United States. The Telekino consisted

of a robot that executed commands transmitted by electromagnetic waves. It constituted the

world's first apparatus for radio control and was a pioneer in the field of remote control [1]

The first remote-controlled model aeroplane flew in 1932, and the use of remote control

technology for military purposes was worked intensively during the Second World War, one

result of this being the German Wasserfall missile.

By the late 1930s, several radio manufacturers offered remote controls for some of their higher-

end models.Most of these were connected to the set being controlled by wires, but the Philco

Mystery Control (1939) was a battery-operated low-frequency radio transmitter. That makes it

the first wireless remote control for consumer electronic devices.

The first remote intended to control a television was developed by Zenith Radio Corporation in

1950. The remote, called "Lazy Bones", was connected to the television by a wire. A wireless

remote control, the "Flashmatic", was developed in 1955, it worked by shining a beam of light

onto a photoelectric cell, but the cell did not distinguish between light from the remote and light

from other sources. The Flasmatic also had to be pointed very precisely at the receiver in order to

work.[4]


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In the late 2000s-early 2010s, a number of Smartphone and portable media player platforms were

provided with installable software applications which allow for the remote controlling of media

centers and media players on home theater PCs and general-purpose personal computers over wi-

Fi, such as iTunes Remote on iOS. In comparison to the user interfaces of physically buttoned

dedicated remote control devices, the user interfaces of these remote control applications are

designed to take advantage of the dynamic graphics offered by usually touch screened handheld

devices, making for larger virtual buttons and virtual keyboards.

2.2.2 Voice Operated Remote Control

The worlds most advanced remote control lets users tell the system what to do-without even

lifting a finger![5]. Why control your 21-st century system with yesterday's old-fashioned push-

button technology? It is now possible to drive sales with a modern voice-operated remote

control. This technology is so advanced that it has been used in interplanetary space probes.

The voice Operated Remote Control Technology uses the sound of your voice to control your

system. The remote control converts spoken words into remote control signals. The system is

able to recognize over fifty commandsin any language. That means that you can operate this

system successfully only when you are close to it. When you go far away such that your voice

can not be heard by the system, you would make no impact.

2.2.3. Opto Components

. The infrared diode modulates at a speed corresponding to a particular function. When seen

through a digital camera, the diode appears to illuminate purple light.


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Most remote controls for electronic appliances use a near infrared diode to emit a beam of light

that reaches the device. A 940 nm wavelength LED is typical. This infrared light is invisible to

the human eye, but picked up by sensors on the receiving device. Video cameras see the diode as

if it produces visible purple light.

With a single channel (single-function, one-button) remote control the presence of a carrier

signal can be used to trigger a function. For multi-channel (normal multi-function) remote

controls more sophisticated procedures are necessary: one consists of modulating the carrier with

signals of different frequency. After the demodulation of the received signal, the appropriate

frequency filters are applied to separate the respective signals. Nowadays digital procedures are

more commonly used. One can often hear the signals being modulated on the infrared carrier by

operating a remote control in very close proximity to an AM radio not tuned to a station.

2.2.4. Consumer Electronics

Different manufacturers of infrared remote controls use different protocols to transmit the

infrared commands. The RC-5 protocol that has its origins within Philips uses, for instance, a

total of 14 bits for each button press. The bit pattern is modulated onto a carrier frequency that,

again, can be different for different manufacturers and standards, in the case of RC-5, a 36 kHz

carrier is being used. Other consumer infrared protocols are different.

2.2.5. Principles of Infrared Operation

Since infrared (IR) remote controls use light, they require line of sight to operate the destination

device. The signal can, however, be reflected by mirrors, just like any other light source. If

operation is required where no line of sight is possible, for instance when controlling equipment


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in another room or installed in a cabinet, many brands of IR extenders are available for this on

the market. Most of these have an IR receiver, picking up the IR signal and relaying it via radio

waves to the remote part, which has an IR transmitter mimicking the original IR control. Infrared

receivers also tend to have a more or less limited operating angle, which mainly depends on the

optical characteristics of the phototransistor. However, its easy to increase the operating angle

using a dull transparent object in front of the receiver.

2.2.6. Radio Remote Control

Radio remote control (RF Remote Control) is a way to control distance objects using a variety of

radio signals transmitted by the remote control device. By using radio remote control system,

you can control a variety of mechanical or electronic devices to complete various operations,

such as closing circuit, move handle, start motor, etc. As a complementary method to infrared

remote control type, the radio remote control is widely used in garage door remote control,

electric gate remote control, automatic barrier remote control, burglar alarm, industrial remote

control and wireless home alarm systems.

A radio remote control system commonly has two parts: transmit and receive. Transmitter part is

generally divided into two types, namely, rf remote control and transmitter module. By the way

of using, the rf remote control can be used independently as a whole while the transmitter

module is used as a component in the circuit, the advantage of using transmitter model is it can

be seamlessly connected with application circuit, and it's size is small, but users must have a

knowledge of the circuit to use the transmitter module, the rf remote control is much more easy

to use at this point.


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Receiver part also is generally divided into two types, namely, the super-regenerative receiver

and the super heterodyne receiver, super-regenerative receiver is actually working like the

regeneration of under intermittent oscillation detection circuit while Super heterodyne type is

working like the one in radio receiver. Super heterodyne receiver features stability, high

sensitivity and the anti-interference ability is relatively good, while super-regenerative receiver

features a small package and the price is also cheaper.

2.2.7. Opto-coupler

Figure 2.1 Opto Isolator

Figure2.1 shows an LED driving a phototransistor. This is a much more sensitive and perfect

isolator for coupling between high voltage devices and low voltage ones. The idea is straight

forward. Any change in Vin produces changes in the LED, which changes the current through the

phototransistor. In turn, this produces changes in voltage across the collector-emitter terminals.

Therefore, a signal voltage is coupled from the input circuit to the output circuit.

Again, the big advantage of an opto-coupler is the electrical isolation between the input and the

output circuits. Stated in another manner, common for the input is different from the common for


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the output circuit because of this, no conductive path exists between the two circuits. This means

that you can ground one of the circuits and float the other. For instance, the input circuit can be

grounded to the chassis of the equipment, while the common of the output side is ungrounded.

Figure 2.2 shows the circuit symbol for an Opto-Coupler.

Figure 2.2 Opto-coupler symbol.

The current of the LED in the opto-coupler package is calculated from the following formula:

Rs

VinILED 414.1

and the collector saturation current of the photo transistor is calculated from:

IC (SAT) =VCC/RC

2.3. The 555 Timer

Fig. 2.3. 555 Timer Symbol

The figure 2.3 above represents the circuit symbol for a 555 Timer by courtesy 555-timer-

circuits.com


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Figure 2.4 Inner Components of 555 timer

The figure 2.4 shows the inner components that make up the 555 timer which is an integrated

circuit. The 555 timer combines a relaxation oscillator, two comparators, an RS-Flip Flop, and a

discharge transistor. This versatile IC has so many applications that it has become an industrial

standard. Figure 2.4 is a simplified circuit diagram of an NE555 timer, an 8pin IC timer. The

upper comparator has a threshold input (pin6) and control input (pin5). In most applications, the

control input is not used, so that the control voltage equals +2VCC/3. Whenever the threshold

voltage exceeds the control voltage, the high output from the comparator will set the flip flop.

The collector of the discharge transistor goes to (pin7). When this pin is connected to an external

timing capacitor, a high Q output from the flip flop will saturate the transistor and discharge the

capacitor. When a LOW output from the flip-flop, the transistor open and the capacitor charges

as previously described. The complementary signal out of the flip flop goes to (pin3), the output.

When the external reset (pin4) is grounded, it inhibits the device (prevents it from working). This


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ON/OFF feature is sometimes useful. In most application, however, the external reset is not used,

and (pin4) is tied directly to the supply voltage.

The lower comparator, its inverting input is called the trigger (pin2). Because of the voltage

divider, the non-inverting input has fixed voltage of +VCC/3. When the trigger input voltage is

slightly less than +VCC/3, the op-amp goes high and reset the flip flop.

Finally, (pin1) is the chip ground, while (pin8) is the supply pin. The 555 timer works maximum

supply voltage of 16V.

Monostable-modeA monostable circuit produces one pulse of a set length in response to a trigger input such as a

push button. The output of the circuit stays in the low state until there is a trigger input, hence the

name "monostable" meaning "one stable state". This type of circuit is ideal for use in a "push to

operate" system for a model displayed at exhibitions. A visitor can push a button to start a

model's mechanism moving, and the mechanism will automatically switch off after a set time.

Fig. 2.5 555 timer in Monostable Mode.


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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 a motor on

and off at regular intervals. It can also be used to flash lamps and LEDs, and is useful as a 'clock'

pulse for other digital ICs and circuits.

Fig. 2.6 555 Timer in Astable Mode

The following formulas are used during application designs of the 555 timer:

Pulse width is: W = 1.1RC.

Frequency is:CRRT

f)2(

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Time is: .0693(R1+2R2)C

2.4. Operational Amplifier

An operational amplifier, or op-amp, is linear integrated circuit that has a very high voltage gain,

high input impedance, and low output impedance. An op-amp is never used without the

application of either negative or positive feedback.


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Figure 2.7 Op-amp Symbol

The symbol of an op-amp is show in fig 2.7. It has two input terminals and one output. One of

the terminals labeled (-) is known as the inverting input since the signal applied to this terminal

appears at the output with opposite polarity, i.e, a sinusoidal input signal will experience a phase

shift of 180o

. The other input terminal labeled (+), is the non-inverting input, and a signal

applied to this terminal appears at the output without inversion. The op-amp actualizes the

difference between the voltages applied to it input terminals. Two further terminals are provided

for the connection of positive and negative power supply voltages. Both voltages are necessary

so that the output voltage can vary between zero volts. Most Op-amps will operate satisfactory

from a wide range of supply voltages and few are designed to operate from single supply

voltage.

Op-amps are either bipolar, all bipolar, FET or mixed fabrication and have JFET.

Vd+

Vo

Rin~inf Rout~0

Input 1

Input 2

Output

+Vcc

-Vcc


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Devices that have a FET input circuit are known as BiFET Op-amps and devices that employ a

MOSFET input are BIMOS op-amp. There are also other kinds of op-amp in use: (a) the current

differencing amplifier (CDA), and (b) the operational transconductance amplifier (OTA).

2.4.1. Parameters of Operational Amplifiers

(a) Gain:

The ideal op-amp would have an infinite open-loop differential gain but, naturally, practical

circuit falls far short of this. Practical op-amps have open-loop gains which vary considerably

from one type to another but may be somewhere between 25,000 and 300,000. The gain is often

(incorrectly) expressed in decibels.

(b) Input Resistance:

Ideally, the input resistance of an op-amp is infinitely high but in practice it may be any value

between 250Kohm and 40Mohm for bipolar transistor input and 1012

ohms for FET input type.

(c) Output Resistance:

Since an op-amp is essentially a voltage amplifier, its output resistance should be as low as

possible. Practical output resistance is in the region of 100 ohms.

(d) Input Offset Voltage:

Ideally, the output voltage of an op-amp should be zero when zero volt signal is applied to both

of its inputs. For any practical amplifier it is found that an output voltage does not exist for zero

input voltage. This voltage arises because of small unbalances within the op-amp but, for

convenience, it is assumed to be caused by an input offset voltage Vos. The input offset voltage of

an op-amp is equal to the output voltage for zero input voltage divided by the open-loop voltage

gain of the op-amp.


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The input offset voltage is in the range of 10mV to 7mV for bipolar transistor input type and

0.5mV to 15mV for FET input type. Although, the offset voltage is small it is amplified by the

circuit and may not be of negligible amplitude at the nulling out the effect of Vos.

(e) Input Bias Current:

The input circuit of an op-amp is always a differential amplifier and in many cases bipolar

transistors are employed. Both transistor must be provide with base current, and to keep the

circuit balance these base currents should be of the equal value. In all op-amps, however,

manufacture imperfections means that there is always some difference between the base bias

currents. The input bias current is one-half the sum of the bias current taken by each input of the

op-amp. Typically, the input bias current is 10 to 50nA for a bipolar transistor input op-amp and

as low as 10 to 100pA for FET input type.

(f) Input Offset Current:

The difference between the bias current is known as the input offset current. Typical values are

in the region of 3 to 20nA for bipolar transistor in put type and a few pA for FET input type.

2.5. The Transistor as a Switch

When used as an AC signal amplifier, the transistors Base biasing voltage is applied so that it

always operates within its "active" region. That is the linear parts of the output characteristics

curves are used. However, both the NPN & PNP type bipolar transistors can be made to operate

as an "ON/OFF" type solid state switch by biasing its Base differently to that of an amplifier.

Solid state switches are one of the main applications of transistors. Transistor switches are used

for controlling high power devices such as motors, solenoids or lamps, but they can also be used

in digital electronics and logic gate circuits.


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If the circuit uses the Bipolar Transistor as a Switch; then the biasing of the transistor, either

NPN or PNP, is arranged to operate at the sides of the V-Icharacteristics curves as shown in

Fig.2.8 below. The areas of operation for a transistor switch are known as the Saturation Region

and the Cut-off Region. This means then that we can ignore the operating Q-point biasing and

voltage divider circuitry required for amplification,

Operating Regions

Figure 2.8 Load line of Transistor

The pink shaded area at the bottom of the curves represents the "Cut-off" region while the blue

area to the left represents the "Saturation" region of the transistor. Both these transistor regions

are defined as:


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a. Cut-off Region

Here the operating conditions of the transistor are zero input base current ( I B ), zero output

collector current ( IC ) and maximum collector voltage ( VCE ) which results in a large depletion

layer and no current flowing through the device. Therefore the transistor is switched "Fully-

OFF". With the cut-off region, the following features are considered.

Figure 2.9 Cut-Off

The input and Base are grounded (0v)

Base-Emitter voltage VBE < 0.7V

Base-Emitter junction is reverse

biased

Base-Collector junction is reverse

biased

Transistor is "fully-OFF" (Cut-off

region)

No Collector current flows ( IC = 0 )

VOUT = VCE = VCC = "1"

Transistor operates as an "open

switch"

Then we can define the "cut-off region" or "OFF mode" when using a bipolar transistor as a

switch as being, both junctions reverse biased, IB < 0.7V and IC = 0. For a PNP transistor, the

Emitter potential must be negative with respect to the Base.

b. Saturation Region

Here the transistor will be biased so that the maximum amount of base current is applied,

resulting in maximum collector current resulting in the minimum collector emitter voltage drop

which results in the depletion layer being as small as possible and maximum current flowing

through the transistor. Therefore the transistor is switched "Fully-ON".


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In the Saturation Region the following Characteristics are observed:

Figure 2.10 Saturation of Transistor

The input and Base are connected to

VCC

ase-Emitter voltage VBE > 0.7V

Base-Emitter junction is forward biased

Base-Collector junction is forward

biased

Transistor is "fully-ON" (saturation

region)

Max Collector current flows (IC =

Vcc/RL)

VCE = 0 (ideal saturation)

VOUT = VCE = "0"

Transistor operates as a "closed switch"

Then we can define the "saturation region" or "ON mode" when using a bipolar transistor as a

switch as being, both junctions forward biased, IB > 0.7V and IC = Maximum. For a PNP

transistor, the Emitter potential must be positive with respect to the Base.

Then the transistor operates as a "single-pole single-throw" (SPST) solid state switch. With a

zero signal applied to the Base of the transistor it turns "OFF" acting like an open switch and

zero collector current flows. With a positive signal applied to the Base of the transistor it turns

"ON" acting like a closed switch and maximum circuit current flows through the device.

An example of an NPN Transistor as a switch being used to operate a relay is given below. With

inductive loads such as relays or solenoids a flywheel diode is placed across the load to dissipate

the back EMF generated by the inductive load when the transistor switches "OFF" and so protect


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the transistor from damage. If the load is of a very high current or voltage nature, such as motors,

heaters etc, then the load current can be controlled via a suitable relay as shown.

Basic NPN Transistor Switching Circuit

Figure 2.11 shows the circuit diagram for an NPN Transistor Switch.

Figure 2.11 NPN Transistor Switch

It should be noted that to operate the transistor as a switch the transistor needs to be turned either

fully "OFF" (cut-off) or fully "ON" (saturated). An ideal transistor switch would have infinite

circuit resistance between the Collector and Emitter when turned "fully-OFF" resulting in zero

current flowing through it and zero resistance between the Collector and Emitter when turned

"fully-ON", resulting in maximum current flow. In practice when the transistor is turned "OFF",

small leakage currents flow through the transistor and when fully "ON" the device has a low

resistance value causing a small saturation voltage (VCE) across it. Even though the transistor is

not a perfect switch, in both the cut-off and saturation regions the power dissipated by the

transistor is at its minimum.

In order for the Base current to flow, the Base input terminal must be made more positive than

the Emitter by increasing it above the 0.7 volts needed for a silicon device.


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By varying this Base-Emitter voltage VBE, the Base current is also altered and which in turn

controls the amount of Collector current flowing through the transistor. When maximum

Collector current flows the transistor is said to be saturated. The value of the Base resistor

determines how much input voltage is required and corresponding Base current to switch the

transistor fully "ON".

2.6. The LM317 Adjustable Voltage Regulator

The LM317 is a three terminal positive voltage regulator that can supply 1.5 amperes of load

current over an adjustable output range of 1.25 to 37volts. The load regulation is 0 .01 percent.

The line regulation is 0.01 percent; this means that output voltage changes only 0.01 percent for

each volt of input change. The ripple regulation is 80 dB. The data sheet of an LM317 gives this

formula for output voltage:

Fig 2.12 Voltage Regulator Symbol

1

R

R1.25V

1

2ou t

This is valid from 1.25 to 37 volt. Typically, the filter capacitor is selected to get a peak-to-peak

ripple of about 10 percent. Since the regulator has about 80db of ripple rejection, the final peak-

to-peak ripple is around 0.001 percent.


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2.7. Logic Gate

A logic gate is a circuit that has one or more input signals and only one output signal. In the

analysation of all logic gates, it is very necessary to make use of the truth table. The Truth table

shows all the input possibilities and the corresponding output for each input.

2.7.1. NAND Gate

The NAND gate has minimum of two or more inputs but only one output. The logic symbol for a

two input NAND gate is shown in fig 2.13, and the truth table is in below: the output, marked

X is the output and the inputs are A and B.

Fig.2.13. NAND gate symbol

Table 2.0: Truth Table of NAND GATE

Input A Input B Output X

0 0 1

0 1 1

1 0 1

1 1 0

The X output is HIGH if either or both A and B are LOW. The X output is LOW only when both

inputs A and B are HIGH. The NAND actually performs a logic function identical to that of an

AND gate followed by an inverter.

2.7.2. The JK Flip Flop

The characteristic table of the JK flip-flop is shown below.

The main difference between the JK flip-flop and the SR flip-flop is that the JK allows an input J

= 1 and K = 1, which causes the state of the flip-flop to change; Q = Q


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Another variation on a theme of Bistable Multivibrators is the J-K flip-flop. Essentially, this is a

modified version of an S-R flip-flop with no "invalid" or "illegal" output state.

Figure 2.14 J-K Flip flop

What used to be the S and R inputs are now called the J and K inputs, respectively. The old two-

input AND gates have been replaced with 3-input AND gates, and the third input of each gate

receives feedback from the Q and Qoutputs. What this does is that it permits the J input to have

effect only when the circuit is reset, and permit the K input to have effect only when the circuit is

set. In other words, the two inputs are interlocked, to use a relay logic term, so that they cannot

both be activated simultaneously. If the circuit is "set," the J input is inhibited by the 0 status of

Q through the lower AND gate; if the circuit is "reset," the K input is inhibited by the 0 status of

Q through the upper AND gate.

When both J and K inputs are 1, however, something unique happens. Because of the selective

inhibiting action of those 3-input AND gates, a "set" state inhibits input J so that the flip-flop

acts as if J=0 while K=1 when in fact both are 1. On the next clock pulse, the outputs will switch

("toggle") from set (Q=1 and not-Q=0) to reset (Q=0 and Q=1). Conversely, a "reset" state

inhibits input K so that the flip-flop acts as if J=1 and K=0 when in fact both are 1. The next

clock pulse toggles the circuit again from reset to set.


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The end result is that the S-R flip-flop's "invalid" state is eliminated (along with the race

condition it engendered) and we get a useful feature as a bonus: the ability to toggle between the

two (bistable) output states with every transition of the clock input signal.

2.8. Stepper Motor

A Stepper Motor (orstep motor) is a brushless, electric motor that can divide a full rotation

into a large number of steps. The motor's position can be controlled precisely without any

feedback mechanism as long as the motors rating is enough for the particular application.

The accurate control of a body by reason of its weight, velocity, inertia and distance can be

termed Motion Control in electronics. The various types of motion control mechanisms are

stepper motors, Brushless servo, linear Step motor, servo and DC Brush.

This project concentrates on step motor technology.

Fundamentally, stepper motor is a synchronous motor with the magnetic field electronically

switched to rotate the armature magnet around.

Permanent Magnet Stepper (can be subdivided in to 'tin-can' and 'hybrid', tin-can being a cheaper

product, and hybrid with higher quality bearings, smaller step angle, higher power density)

Hybrid Synchronous Stepper Variable Reluctance Stepper Lavet type stepping motor

Permanent magnet motors use a permanent magnet (PM) in the rotor and operate on the

attraction or repulsion between the rotor PM and the stator electromagnets. Variable reluctance

(VR) motors have a plain iron rotor and operate based on the principle that minimum reluctance


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occurs with minimum gap, hence the rotor points are attracted toward the stator magnet poles.

Hybrid stepper motors are named because they use a combination of PM and VR techniques to

achieve maximum power in a small package size.

2.9. Dual Tone Multi-Frequency

Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over

analog telephone lines in the voice-frequency band between telephone handsets and other

communications devices and the switching center. The version of DTMF that is used in push-

button telephone for tone dialing is known as Touch-Tone. It was first used by AT&T in

commerce, using that name as a registered trademark. DTMF is standardized by ITU-T

Recommendation Q.23. It is also known in the UK asMF4.

The DTMF keypad is laid out in a 44 matrix, with each row representing a low frequency, and

each column representing a high frequency. Pressing a single key (such as '0' ) will send a

sinusoidal tone for each of the two frequencies (941Hz and 1336 Hz)). The original keypads had

levers inside, so each button activated two contacts. The multiple tones are the reason for calling

the system multi-frequency. These tones are then decoded by the switching center to determine

which key was pressed.

Table 2.1 DTMF keypad frequencies (with

sound clips)

1209 Hz 1336 Hz 1477 Hz 1633 Hz

697 Hz 1 2 3 A

770 Hz 4 5 6 B

7 8 9 C

852 Hz

941 Hz * 0 # D


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2.9.1. Resistors

If there was not such a thing as resistance, the subject of electronics would not have existed; only

infinite currents would flow and voltages would not exist either.[5]. It has been a necessity to

reduce the flow of current if current is to be properly utilized. Resistors are components that

resist the flow of current and are said to have a resistance which is measured in ohms (_),

named after George Ohm, who formulated the law (Ohms Law) by which the voltage and current

through a conductor are related. His law gave birth to the formula:

I=V/R,

WhereIis the current flowing, measured in amps,

Vis the voltage across the conductor, and

R is the resistance of the conductor, measured in ohms.

From this equation, you can see that, for a constant value of voltage, V,

If the resistance goes up, the current will go down, and vice versa.

Figure 2.15 Symbols for Resistor

The circuit symbols for resistors are shown in figure 2.15. Resistors are made in several ways,

the cheapest using carbon; another type is usually made from a ceramic cylinder having a very

thin film of metal placed in it the thinner the film, the greater the resistance. All resistors are

coated with a thin film of insulation.


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2.9.2. The Resistor Color Code

Each resistor has colour bands on it which enable us to see what value of Resistance it has. There

are normally three (but sometimes four) at one end. The fourth one gives the Tolerance levels.

The colours indicate figures, according to the table 2.2 below.

Table 2.2 Resitor color code

Tolerance Levels:Gold- 5%

Silver- 10%

Colour Value Colour Value

Black 0 Green 5

Brown 1 Blue 6

Red 2 Violet 7

Orange 3 Grey 8

Yellow 4 White 9


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CHAPTER THREE

3.0 METHODOLOGY

3.1. Introduction

This chapter presents the list of the components used in the various blocks put together to form

the project. The techniques used to obtain the design and the procedure through which the design

was translated into the physical built up has been espoused here in this methodology chapter. The

chapter elaborates on how the data for this project were gathered. In this case, it was the

collection of components since our main data for engineering projects revolves around the

availability of every minute component. The tools and other materials that were used to make the

project a reality have been listed so as to make it easy for people who might in the future want to

build this project. Pictures of the soldering processes have been pasted as well.

3.2. Components used for the project

(a). Power Supply Unit

The power supply unit converted the alternating voltage to a smooth direct voltage for the rest of

the units to work. The power supply is the heart of the whole system. The under listed

components form the power supply unit:

Main connecting wire and connectors Power transformer (240v-12v X 2, 1000MA) Diodes (12v, 1N539CD) Capacitors(electrolytic,[2200uF, 16v ] and [470uF, 35v] Positive Voltage regulator[ LM 317T, QNK824] Transistors [MPS 2222A] Resistor [220]


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(b). Dual Tone Multi-frequency ( DTMF) Receiver Unit.

The DTMF block was formed from the components below:

MT8870DE [part code-0728A] Piezo-electric crystal [3.5795MHz] Capacitors [10uF, 16v] Resistors Diodes Voltage regulator

(c). The Decoder Unit

DM74LS138N SN74LS122N SN74LS107AN Opto-coupler(EDR201A0500

(d). Switching Unit

JK flip-flops SN74LS122N SN74LS107AN SPDT relays[ 6v](e). Clock Unit

Timer(NE555P ) SN74LS00N Capacitor [100uF, 16v]


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(f). Call Accept Unit

Timer (LM555CN-JM11AL) ZETTLER (AZ831-2C-50se) Diodes Resistors

All the components mentioned above were mounted and soldered on a Printed Circuit Board.

And of course, wires of sizes less than or equal to 1mm2

and a mobile phone handset with a

registered SIM card and then the slide window that is to be controlled through a stepper motor

were included.

3.3. Tools

The various tools were employed in the project built-up:

(a) Hand tools Set of Screw Drivers: These were used to tighten screws of the case and the matrix

boards.

Side Cutter: This was used to cut terminals of passive devices and cables Pair of Long Nose Pliers: This one was used to hold and tighten bolt and nuts.(b) Machine tools A Band Saw was employed to cut mica sheet for the casing Grinding Machine was also used to grind the surface of aluminum sheet for the motor

holder

Electric Sander was used to sooth the surface wooden frame of the window Electric Hand Drill: it was used to drill holes in the mica sheet for the case and holes in

the matrix boards.


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(c) Instruments

Oscilloscope

An oscilloscope was used to observe the voltage and current waveforms and for the

measurement of the frequency of the electrical signals.

Digital MultimeterDigital Multimeter was used for the measurement of voltage, current, resistance, capacitance

and frequencies of the components. The results of the measurements were displayed on liquid

crystal display. Thus, the instrument was used for continuity, resistance, voltage, current and

terminal checks.

Soldering IronThe soldering iron was used in joining the pieces of copper wires to each other and to

terminals. The joining surfaces were first cleaned with a wire brush and then coated with ROSIN

that cleans them chemically and assisted the solder in making a bond.

Lead.A coil of lead with flux was required for the soldering. The flux prevented dry joints in the

soldering process.

3.4. Methods

3.4.1 Designing the Complete Circuit Diagram

CIRCUIT MAKER version 5 Software was used to design the circuit diagram. The various

blocks that formed the project were designed individually before they were merged into one

complete circuit diagram of the project. The results of the designs were saved as picture

document and that enabled copying into Microsoft Office 2007 Word document.


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3.4.2. Tests on Opto Coupler

Figure 3.1a . Testing Opto Coupler with an opened switch

Consider how the Opto Isolator was tested as shown in Fig. 3.1a above:

(a)When the switch was opened; no current flows through the LED in the Opto Coupler andthe LED emits no light. So the output transistor remained at Saturation. The collector

voltage measured was 5volts (Vc=5V).

Figure 3.1 b. Testing Opto- coupler when switch was closed.

In fig3.1 b, when the switch was closed, the LED emits light and the output transistor cuts off.

The collector voltage was approximately zero (Vc=0).


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3.4.3. One Shot Mono Stable Flip flop

Figure 3.2 Monostable Flip flop Test

By following strictly the directives in the manufacturers data sheet the one shot mono stable flip

flop was built. A1 and A2 are active LOW trigger inputs which were tied together and connected

to a push button switch SW1 as shown in fig 3.2 above .

Table 3.1. One Shot Monostable Flip Flop output state

As shown in table 3.1 at the initial state of the one shot mono stable flip flop, when SW1 was

not closed, Q (pin 8) connected to the LED1 was OFF and Q (pin 6) connected to LED2 came

ON. When SW1 was pressed closed, both Q and Q outputs flip flop (*change state)

momentarily according to the time constant of RC. The Q output was used to clock the call

connected JK flip flop and Q output was used to trigger the call accept circuit.

SW1 Q Q

Opened 0 1

Closed 1 0


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3.4.4. Switching Relay with a Transistor Switch

Due to the fast nature by which transistor switch can be, the mechanical switch was substituted

with the transistor. C711, bipolar transistor was used in place SW1.

Fig3.3. Transistor switch for relay

3.4.5. Transfer of the Design to the Printed Circuit Board

As stated in 3.21, the design for the individual block units were wire- soldered onto the printed

circuit board. Below is a picture showing how the blocks were connected to one another.

Figure 3.4 Pictures of Circuits and Soldering process.

The power supply unit, the DTMF receiver unit, the switching unit and the call accept part were

joined together to form the project.


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CHAPTER FOUR

4.0 SYSTEM DESIGN, DEVELOPMENT AND IMPLEMENTATION

4.1 System Design

Figure 4.1 Block Diagram of Tele-remote system

The individual units in the block diagram was explained by the aid of circuit diagrams as can be

seen in the complete circuit diagram below to make up the design of the project.

4.1.1. Design Calculations

Relay Driver:

The following are the design calculations of the relay driver.

Transistor specification (transistor ratings from the manufacturers data sheet)

VCEO 30v

VCBO 60v

VEBO 5v

IC 800mA

PD 500mW


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All voltage ratings are reverse breakdown voltages. The first rating is V CEO, which stand for the

voltage from collector to emitter with the base open.

VCBO is the voltage between the collector and the base with the emitter open.

VEBO is the voltage from the emitter to the base with the collector open.

IC is the maximum dc collector current rating: this means that C711 can handle up to 800mA of

steady current. The last ratings is PD, the maximum power rating of the device

PD=VCEIC, where PD is power dissipated, VCE is collect-Emitter voltage and Ic is collector

current.

The VCE of the C711 is 12v and IC= 98.36mA, then PD= 118.032mW

This is less than power rating, 500mW. As with breakdown voltage, a good design should

include a safety factor to ensure a longer operating life for the transistor. Safety factor of 2 more

are common practice.

As the maximum power rating of C711 is 500mW, a safety of 2 is required a power dissipation

less than 400mW.

The input voltage to the base of the transistor C711 is 4.5v; this is the voltage on the Q outputs of

JK FF1 and JK FF2.

The base current is calculated from;Rin

0.7v-VinIB

Where Vin = 4.5v, 0.7v is intrinsic PN junction voltage of a silicon transistor (threshold voltage

of silicon transistor)

3.8mA1000

0.7v-4.5vIB


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Saturation:

C

CC(SAT)

R

VIC

73.52mA68

5vIC(SAT)

Where, RC is the collector resistor, and instead of fixed resistor, because the transistor is used as

a relay driver, RC is the coil resistance of the relay.

Cutoff:

The cutoff voltage is the supply voltage minus the sum of the voltage around the collector and is

VCC-RCIC=0

Cutoff voltage = 5v-(68 73.52 10-3

)

Cutoff = 0v

Opto- Coupler:

The following formulas were used to calculate the design of the Opto- coupler.

The light emitting diode side of the Opto- coupler; the LED current is

R

V1.414

I

CC

LED

Where ILED is the light emitting diode current; 1.414 is a constant, VCC is the supply voltage to

the light emitting diode and R is the limiting resistor.

6.363mA1000

v5.41.414ILED

ILED = 6.363mA

The photo transistor side of the Opto- coupler: the saturation value of the photo transistor current

isC

CCC(SAT)

R

VI


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Where IC(SAT) is the saturation current (collector current), VCC is the supply voltage to the photo

transistor and Rc is the collector resistor of the photo transistor.

5mA

1000

5vIC(SAT)

IC(SAT) = 5mA

Cutoff:

The cutoff voltage is the supply voltage minus the sum of the voltage around the collector and is

VCC-RCIC=0

Cutoff voltage = 5v-(1000 5 10-3

)

Cutoff = 0v

Clock Generator Time:

T = .069(R1+2R2)C

T = .69(1000+200000)10 10-6

T = 1.3869sec


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4.1.2. Complete Circuit Diagram

Figure 4.2 Complete Circuit of the Project


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4.2. Development and Implementation

4.2.1 Stages of development and Implementation

a. Ring detect unit

Figure 4.3. Ring detect unit

When the mobile number assigned to the system is called and the ringing tone is transmitted on

the link, the ringing signal from the output of the mobile phone normally is sound wave

converted into alternating signal is then again converted to direct current by zener diode D1

during the positive half cycle of the incoming signal and regulates its voltage at the same time.

The zener diode is 2.5v which is sufficiently good for such an application. Diode D3 is reversed

biased in parallel with the internal LED of the opto-coupler to sink any accidental negative

feedback which may damage the LED of the opto device. The conversion that has been done by

the Zener diode is series of pulsating-semi- direct current voltage. This pulsating semi direct

current voltage is sufficient enough to make the internal LED of the opto-coupler to illuminate

and the output transistor which is normally in saturation mode cut-off to trigger the single shot

monostable flip flop to momentarily send a single shot pulse to change its Q state depending on

the time constant of RC.


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Transistor Q1 is also normally saturated, but the momentary change of the Q state of the one

shot monostable flip flop causes it to cut off momentarily. And energizes relay RLY1 to make

contact momentarily (* one shot contact) to accept call.

b. Idle Detect circuit

Figure 4.4 Idle detect circuit

The Idle Detect is made up of two binary coded decimal counter (BCD counter) and two NAND

gates. The BCD counters are complementary metal oxide semiconductor integrated circuit

(CMOS) and the NAND gates are transistor-transistor logic (TTL) type. The first BCD counter

was configured to count decimal ten and second BCD counter U2B to count four. Clock input

CP0 accepts HIGH signal where the clock system is connected.

Q0 and Q3 outputs of first counter were connected to the two inputs of first NAND gate and its

output is connected to the clock input CP0 of the second BCD counter. Q2 of the second BCD

counter was connected to the bridged inputs of the second NAND gate. CP1 of the first counter

and CP1 of the second counter were tied together to ground, which serves as ENABLE for the

two BCD counters. As the MR of the two BCD counters are connected to the QN of the JK flip

flop, at the initial state of the JK flip flop QN is HIGH and it keeps the call timer at reset state

while call is not detected. When the system is called and call is detected. i.e, when the system is


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called and the call detector circuitry accepted call automatically, the QN which was HIGH at its

initial state, changes from HIGH to LOW and the counter starts to count for a period of 40

seconds. Commands are supposed to be sent within the period of 40 seconds. If one fails to send

the command, then after 40 seconds the system cuts off the communication link by resetting the

call detector JK flip flop.

On the other hand, if a command code is sent within the 40 seconds count, then the pre-

amplification circuit leads the process as below.

c. Pre-amplifier circuit details

Figure 4.5. Pre-amplifier circuit

The input amplifier consisted of an operational amplifier (op-amp) LM741, and its associated

devices. The input amplifier is designed as an inverting amplifier with negative feedback. The

feedback network is formed by a resistor whose value is 1M. The purpose of the feedback

resistor is to feed a fraction of the output signal back to the inverting input to regulate distortion

and give a high gain to the LOW DTMF signals coming from the output of the mobile phone.

The Resistor and capacitor form the input coupling

network. The Capacitor as part of the coupling network eliminates unwanted direct current

components of the DTMF tone signal. The gain of the amplifier depends on the values of the

resistors.


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d. Dual Tone Multi-frequency (DTMF) receiver connections

Figure 4.6 Dual Tone Multifrequency ( DTMF) receiver connections

DTMF (MT8870) is a dual tone multi-frequency receiver which receives DTMF tones through

an RC input network. The MT8870 has an internal clock whose frequency is set by an external

piezoelectric crystal (XTAL1). The capacitor and resistor set the time guard of the receiver and

the binary output is derived from Q1, Q2, Q3 and Q4. For the purpose of this project to be

achieved only three of the four outputs are used.

e. Decoder system

Figure 4.7 Decoder systemThe 74LS138 is a TTL decoder-demultiplexer chip. This is because it can be used as either a

decoder or a demultiplexer. It has three control inputs and eight outputs as well as three data


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inputs. The presence of the data inputs makes it a demultiplexer. The upper inputs are labeled

A0, A1. and A2 and they are controlled or data select inputs. The lower three inputs are labeled

E1, E2, and E3 and they are the data inputs. In order to use this demultiplexer as a decoder, E1

and E2 which are data inputs were made active LOW by tying them to ground and E3 is active

HIGH data input as connected to +5V.

f. Switching Unit

Figure 4.9 . Output switching system

From the decoder outputs, two decoded signals are used to control the J and K inputs of

(74LS107). The 74LS107 is a TTL fabricated JK flip flop that has four control inputs and two

outputs. The inputs are J, K, CP and R. The J inputs when HIGH sets the flip -flop to change

output state making Q=1 and QN=0. When the K input is HIGH, the outputs change to its initial

state. The R input is used to reset the flip flop. CP is the control pulse input and is active only

during the negative going edged of a pulse to enable the flip flop to change state.

At the initial state of the JK flip flop, Q=0 and QN=1, and as Q is connected to the transistor Q1

through R3 and the initial state of transistor Q1 in saturation mode , and relay RLY1 make

contact is opened when the mains terminal L, N, E is connected to 220 volt AC mains. When the

decoder output connected to J is high, the JK flip flop sets the Q output to HIGH to cause

transistor Q1 to cut off to energize the relay RLY1, then when the relay make , current flow to


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stepper motor. If the supply to motor is to turn off, then the decoder output connected to the K

input of the flip flop should be HIGH.

Turning ON and OFF supply to the motor occurs only when the clock input sees negative going

edge of the clock pulse. By applying logic LOW to R reset the flip flop no matter what state it is.

g. The Power Supply System

Shown in the above figure is the system power supply. The transformer input voltage is 220vac

and its output is 12vac. The power has multiple voltages. The ac output was converted by four

rectify diodes and smoothed by the capacitors. The LM 7805 is voltage regulator which regulates

the positive 12 volts to 5 volts to supply the digital chips.

In all, the power supply gives minus 12 volts, positive 12 volts and positive 5 volts. Then +5V

goes to the DTMF receiver IC.

4.22. Operational Instructions for UserAfter all wire connections are done to the various sliding windows, connect the power cord of

the telephone remote switching system for slide windows into 220vac electricity. Press button to

switch on the mobile phone system. Allow some few seconds for the phone initialization. Turn

ON the power and press the reset button to reset the system to synchronize.

Figure 4.10 Power Supply


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When the slide window or door is opened and is required to be closed due to weather uncertainty

from a personal mobile phone or office phone: Dial the assigned number of the system, in this

case 0243935623, the system responds automatically. This action displays on the mobile phone

screen as active. But in case the situation where an office phone is used, ensure that the

telephone instrument is touch button type (DTMF) but not the pulse type. Land line telephone

instrument may not have a screen so you will hear a connection click in the ear piece.

When it is successfully connected to the system, pressing the digit 2on the telephone keypad

will slide close the window or door that the 2 is assigned to. The same should b e done for the

rest of the windows to slide close them. A feedback tone indicates that windows have been

completely closed.

The system must not be turned OFF once connections have been made unless of course you have

decided not to use it for a while. It is strongly recommended that the opening of the slide

windows be done manually when at home in order to save telecommunication charges.


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CHAPTER FIVE

5.0 RESULTS AND DISCUSSION

5.1. Results

The teleremote system was successfully built as a product after its design, development and

implementation. It was tested and the following results were observed:

The teleremote system was able to close the prototype slide door but could not open it.That meets the scope of this project requirement of being able to close the slide door or

window. But for the opening of the slide door or window could conveniently be done

manually. It may not even be that necessary to try to open the sliding windows while no

one is in the house.

The system responded in the same positive manner when MTN customized mobile phonewas replaced with a Vodafone customized mobile phone. It was realized that, the system

works well with all networks.


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5.2 Cost Analysis

5.2.1 Material Cost

Table 5.1 Material cost of the project

component quantity Unit cost (GHC) Total cost(GHC)Power transformer (240v-12v X 2,

1000MA)

2 5 10

Diodes (12v, 1N539CD) 10 2 20

Capacitors(electrolytic),[2200uF, 16v ] 10 2 20

Capacitor (electrolytic) ] and [470uF, 35v] 10 2 20

Positive Voltage regulator[ LM 317T,

QNK824]

3 5 15

Transistors [MPS 2222A] 10 2 20

Resistor [220] 20 1 20

MT8870DE [part code-0728A] 4 20 80

Piezo-electric crystal [3.5795MHz] 4 15 60

Capacitors [10uF, 16v] 6 2 18

DM74LS138N 4 15 60

SN74LS122N 4 15 60

SN74LS107AN 2 10 20

Opto-coupler(EDR201A0500) 2 2 4


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JK flip-flops 8 5 40

SPDT relays[ 6v] 4 3 12

Timer(NE555P ) 2 10 20

Capacitor [100uF, 16v] 1 8 8

SN74LS00N 3 5 15

Slide Window 1 100 100

ZETTLER (AZ831-2C-50se) 2 5 10

Timer (LM555CN-JM11AL) 2 5 10

Printed Circuit Board 2 6 12

Stepper motor 2 25 50

MTN mobile phone 1 35 35

TOTAL 739

5.2.2 Labour Cost

Table 5.2 Labour Cost

Resource Cost Duration

ElectronicsEngineer

GHC 5/ hour 3 hours a day for 20days

Total Labour Cost= GHC 3x20x5

CL =GHC 300


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5.2.3 Overhead Charge

Overhead Charge= 10% of (Material Cost + Labour Cost)

=0.1x (739+300)

=GHC 103.9

Therefore, Total Cost of the Project=(739+300+103.9)

=GHC 1142.9.

5.3. Discussion

The product has achieved its performance specification as stated in the scope. That is, ability to

close the slide window or door. But the opening of the slide door or window could conveniently

be done manually. It may not even be that necessary to try to open the sliding windows while no

one is in the house. When MTN mobile network was replaced with that of Vodafone, the system

worked properly. This is because both networks make use of the DTMF keypad accessories. So

once the network was able to connect a call, the DTMF receiver takes over to serve as the

interface for the rest of the action.

The presence of the limit switch in the window gives feedback to the caller to confirm the

complete closure of the slide window or door. This limit switch is important since the user needs

to be sure that the command given has actually done what it is expected to do. Otherwise, how

can it be notice as to whether the door or window was half closed or whatever? This shows that

the limit switch mechanism is very significant in this project.

In analyzing the cost of the project; it appears to be expensive but it is cheap when compared

with the cost involve when rain water destroys properties costing millions of dollars. This project

is one of its kinds and it is difficult to make any price comparison between it and that in the local

market.


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CHAPTER SIX

6.0 CONCLUSIONS AND RECOMMENDATIONS

6.1 Conclusions

The Tele-remote system was developed to compensate the need for long distance remote control

which cannot be possible with the usual Infrared, Bluetooth and Radio remote systems. It is now

easy to remotely close sliding windows while at millions of miles away from home or office.

This system even though, reliable, could not tell if there was power supply failure to it. The Tele-

remote systems operation is power baseline constrained and cannot function in the required

manner when electrical power fails.

The system is also maintainable should it develop any fault in the near future and if resolved

properly will function the same manner as before. The Tele-remote system to control sliding

windows is not in the local market yet. It is believed to be the first of its kind as far as this

project is concern.

6.2 Recommendations

The teleremote control system is very simple and easy to operate and it is recommended for use

in the house and offices. The system should also be installed at an area where there exist good

mobile network for better reception.

However, it is very obvious, as can be referred from the conclusion that there is the need for

further research into finding out how to incorporate a mechanism that would always give

indications to the user when power outage occurs. It is also required that the string that would be

used for pulling the slide windows, be very strong and smooth.


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Meanwhile the slide glass rail has to be regularly cleaned and lubricated so as to prevent any

resistance to the smooth running of the slide glasses. As can be seen from the design of the

switching unit in page 51, figure 4.3, there could be further advancement to make the Tele-

Remote system include the function of opening the slide window since the design has both

forward and backwards circuit terminations to the motor.

It is strongly advised that the user must almost always ensure that the embedded phones battery

indicates charging when the system is connected to electrical mains power. This is just to make

sure the battery does not run down to put the mobile phone off.

The system must also be handled with care not to drop it, for it is very delicate and can perhaps

be damaged beyond repairs if it is dropped vigorously.


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REFERENCES

[1]Floyd, Charles, Digital Fundamentals, Merill publishing co., 2nd

edition, 2006, p35-50.

[2] Theraja, B.L.Electrical Technology, S.CHAND &COMPANY LTD., VOL.IV. 2002, p1886.

[3]. Sueker, Keith H., Power Electronics Design : A Practitioner's Guide, Newnes, 2005.

P190.

[4]Rashid, M. A., Power Electronics Handbook, Academic Press, 2001.

[5]Dr. Brown, George , Radio & Electronics Cook Book, Newnes, 1st

edition, 2001.p23-45.

[6] http://www.electronics-tutorials.ws/transistor/tran_4.html as at August 22, 2011.

[7] Dissado L. A., Electrical Degradation and Breakdown in polymers Fothergill,

London, 2006, p. 226

[8] Ismail M. Binti, Designing AnInteractive Telephone Base Remote control and Alarm

System, 1st

ed., 2007, pp. 11-15.

[9] B. Gross, "Radiation-induced Charge Storage and Polarization Effects", in

"Electrets",Topics in Applied Physics, Ed: G. M. Sessler, Springer-Verlag, Berlin,

2007,p 10.

[10] Physics of Thin Films: L. Eckertova, Plenum Publishing Co., New York, 2004,

p34.

[11] Brandt S. and Dahmen H.D., The Picture Book of Quantum Mechanics, 2nd

edition, Springer- Verlag, New York, 2003, p. 70..

[12] Mentha V.K.,Electronics made simple, 2nd

edition, Zimse Pub. Co., 2002, pp. 123


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[13] Coskun I. and Ardam H., A Remote Controller for Home and Office Appliances by

Telephone., IEEE Trans. Consumer Electron. Vol. 44. no. 4, 2007, pp. 1291- 1297.

[14] Kasap S. O., Principles of Electrical Engineering Materials, McGraw Hill,

Boston, 2004, p. 184.

[15] Dahmen H.D., The Picture Book of Quantum Mechanics, 2nd

Edition, Springer- Verlag, New York, 2003, p. 73.

[16] Rashid M.A., Power Electronics Handbook, 1st

ed., Academic Press, 2002, p 46

[17] Edward Hughes,Electrical Technology, 7th

edition, ELBS Longman, 2005, p416.

[18] Donald P. Leach,Digital Principles And Applications,6th

edition, Tata McGraw-Hill

Publishing Company Limited, New Delhi, 2006. P121.

[19] ] kulshreshtha D.C,Electronic Devices and Circuits, 2nd

edition(revised),New Age Int. ltd

Publishers, 2006, p65-466.

[20] Willeys R.,Basics in electronic fault Diagnosis, vol.2nd

edition , WBC Publishing, 2007,

p701.


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GLOSSARY

DTMF Dual Tone Multi Frequency

PC Board Printed Circuit Board

DC Direct Current

AC Alternating Current

D/A Digital to Analog

BCD Binary Coded Decimal

TTL Transistor-Transistor Logic

MF Multi Frequency

Op- Amp Operational Amplifier

FET Field Effect Transistor

O/P Output

I/P Input

CDA Current Differential Amplifier

OTA Operational Transconductance Amplifier

JFET Junction Field Effect Transistor

CMOS Complementary Metal Oxide Semiconductor

MOSFET Metal Oxide Semiconductor Field Effect Transistor

BiFET Bipolar Field Effect Transistor

mA Milli Amperes

mV Milli Volts

Ic Collector Current


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VCE CollectorEmitter Voltage

mW Milli Watts

Rc Collector Resistance

M Mega Ohms

K Kilo Ohms

Gnd Ground

mSec Milli Seconds

Vcc Supply Voltage

LED Light Emitting Diode

R Resistor

C Capacitor

dB Decibel


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LIST OF FIGURES

Figure2.1 Opto- Isolator 10

Figure2.2 Opto Coupler Symbol 11

Figure2.3 555 Timer Symbol 11

Figure2.4 Inner Components of 555 Timer Circuit 12

Figure2.5 Timer in Monostable Mode 13

Figure2.6. 555 Timer in Astable Mode 14

Figure 2.7 Op-amp symbol 15

Figure 2.8 Load line of Transistor 18

Figure 2.9 Cut-off 19

Figure 2.10 Saturation of Transistor 20

Figure 2.11 NPN Transistor Switch 21

Figure 2.12 Voltage Regulator Symbol 22

Figure 2.13 NAND Gate Symbol 23

Figure 2.14 J-K Flip-flop 24

Figure 2.15 The Circuit Symbols for Resistors 27

Figure 3.1a Testing Opto Coupler with an opened switch 33

Figure 3.1 b. Testing Opto- coupler when switch was closed 33

Figure 3.2 Monostable Flip flop Test 34

Fig3.3. Transistor Switch for Relay 35

Figure 3.4 Pictures of Circuits and Soldering process. 35

Figure 4.1. Block Diagram of Tele-Remote System 36

Figure 4.2 Complete Circuit of the Project 40


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Figure 4.3. Ring detect unit 41

Figure 4.4 Idle detect circuit 42

Figure 4.5 Pre-amplifier circuit 43

Figure 4.6 Dual Tone Multifrequency (DTMF) receiver connections 44

Figure 4.8. Decoder system 44

Figure 4.9. Output switching system 45

Figure 4.91. Power supply 46


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LIST OF TABLES

Table 2.0 Truth table of NAND gate 23

Table 2. 1 DTMF keypad frequencies 26

Table 2.2 Resistor color code 28

Table 3.1. One Shot Monostable Flip Flop output state 34

Table 5.1 Material Cost 48

Table 5.2 Labour Cost 50

Design and Construction of a Tele-Remote System

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