DESIGN AND CONSTRUCTION OF A SIMPLE TWO WAY INTERCOM. SYSTEM

BY

A PROJECT SUMITTED TO THE DEPARTMENT OF ELECTRICAL AND ELECTRONIC ENGINEERING TECHNOLOGY ABIA STATE

POLYTECHNIC, ABA.

IN PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF NATIONAL DIPLOMA (ND) IN ELECTICAL AND ELECTRONIC

ENGINEERING

JANUARY, 2016

CERTIFICATION

I certify that this project design and construction of a two way intercom system was carried out by me, IGWE LUCKY CHIMEZIE with matriculation number 2013NDM/000137/EE in partial fulfillment for the requirement for the award of the national diploma in electrical/electronic engineering, abia state polytechnic,

aba.

DECLARATION

I hereby declare that this project design and construction of a two way intercom system was designed, constructed and submitted to the department of Electrical/Electronic Engineering, Abia state polytechnic, aba. In partial fulfillment of the requirement for the Award of national diploma.

I further declare that this work has not been submitted to this or any other institution for the award of degree, diploma or equivalent course.

DEDICATION

This project work is dedicated to GOD Almighty and also to my family for their support.

ACKNOWLEDGEMENT.

My profound gratitude goes to GOD Almighty for his grace upone my life.

Am indebted to my supervisor for his professional and fatherly advice in the actualization of this project work and also my co-coordinator for his advice and encouragement.

Special thanks to the staff of Electrical/Electronic Engineering for their academic and moral impartations; you were all great may GOD bless you all amen.

My gratitude also goes to my family members for always being there for me, especially to my brother for his support and also my parents chief and Lolo. Emmanuel igwe for their parental guidance I cannot thank you people enough but keeping asking GOD to keep you all healthy with long life to reap the fruit of your labour Amen.

ABSTRACT

Designing and implementing multiple intercom system that will work without charges has always been a prominent field of interest among many researchers and developers. This project presents developments and potentials of a two way intercom system that allow two way conversations from one location to another within a particular place such as offices, homes, workshops, warehouse. This project writing discussed an intercom system and its component make-up, operation applications and other relevant issues as regards to intercom system. The basic element used in this project are tone generator, audio input source, audio amplifier, output device and medium (cable). As both microphone (input source) are always in operation, 1000uf capacitor was used in the power circuit to avoid loud speaker from being picked up by the microphone enclosed in the same box, causing a very undesired and laud.

TABLE OF CONTENTS

Title……………………………………………………………………….i

Certification…...………………………………………………………….ii

Dedication……………………………………………….……………….iii

Acknowledgement………………………………………………………..iv

Abstract………………………………………………….………………..v

Table of contents…………………………………………………………vi

List of figures…………………………………………………………….vii

Chapter one

1.0 INTRODUCTION

1.1Background of study……………………………………………………………………….1

1.2 Statement of problem……………………………………………………………………2

1.3 Objective of study……………………………………………………………………….2

1.4 Significant of the problem……………………………………………………………………3

1.5 scope and limitation of study………………………………….………3

Chapter two

2Lliterature review…………………………………..……………………5

2.1 Background of study………………………………………………….5

2.2 Historical background…………………………………………………………………6

2.3 Background and mathematical techniques…………………………..…9

2.3.1 How it works…………………………………………………………………….…9

2.3.2 Calculation…………………………………………………………..10

CHAPTER THREE

3 DESIGN METHODOLOGY AND IMPLEMENTATION………………12

3.1 COMPONENT IMPLEMENTATION………………………………………………………12

3.2 COMPONENT IDENTIFICATION AND THEIR VALUES…………………………………………………………………….14

3.3 PREPARING THE VERO BOARD………………………………………………………………………15

3.4.1 INSPECTING THE VERO BOARD………………………………………………………………………15

3.4.2 SOLDERING…………………………………………………………..16

3.5 TESTING THE CIRCUIT………………………………………………..17

3.6 PRINCIPLE OF OPERATION…………………………………………………………………17

3.6.1 POWER SUPPLY :( BATTERY)………………………………………18

3.6.2 INPUT SOURCE: (MICROPHONE)…………………………………...19

3.6.3 OUTPUT DEVICE: (SPEAKER)………………………………………19

3.6.4 MEDIUM: (FLEXIBLE WIRE)………………………………………..19

CHAPTER FOUR

4 DATA PRESENTATION AND ANALYSIS…………………………………………………………………...21

4.1 TONE GENERATOR………………………………………………………………..23

4.4 CALCULATION…………………………………………………………25

CHAPTER FIVE

5 CONCLUSION AND RECOMMENDATION……………………………...29

5.1 CONCLUSION……………………………………………………………29

5.2 RECOMMENDATION……………………………………………………30

REFERENCES…………………………………………………………………32

LIST OF FIGURES

FIG 3.1 application circuit for the 555 timer…………………………………10

Fig 3.2 the block diagram……………………………………………………..13

Fig 3.3 circuit diagram of the audio amplifier………………………………...14

Fig 4.1 circuit diagram of the ringer…................................................................18

Fig 4.2 pin outs of NE555 timer IC…………………………………………....23

Fig 4.3 application circuit for the 555 timer…………………………………...24

Fig 4.4 circuit diagram of the audio amplifier…………………………………26

LIST OF TABLES

Table 4.1 current variation in resistors…………………………………………22

Table 4.2 bill of quantity and evaluation (BEME)………………………….…27

CHAPTER ONE

1. INTRODUCTION

An internal communication system is a system that basically transfers information in the form of electrical signal from one spot to the other within a confirmed location. It is also a private telecommunication system that allows typically two or more location to communicate with each other like telephone does. An intercom is also a personal telecommunications device which facilitates the exchange of messages between two or more locations where standard vocal communication would be difficult or impossible due to distance or obstructions.

This project two way intercom system consist of station linked to each using wire. It uses full duplex .mode a process whereby one can transmit and receive voice calls simultaneously which made transmission medium to be your wires between the two nodes and typical headers on the nodes (separate speaker and microphone, good isolation from sound coming from speaker to the mic element).

1.1 BACKGROUND OF THE STUDY

Technology now has made it possible for various instrument or device to be designed and constructed in other to make human life more profitable and enjoyable. These days, a lot of devices are built based on electrical approach. One of these devices is known as an intercom system.

Perhaps one needs an internal communication. May be may be one want to be able to communicate with his home from his office or garage. Or in a case one is upstairs in a bedroom doing his or her school work, and wants to know when dinner will be ready. May be the person is too weak to get up and shout down the stairs to find out if so, then this simple intercom will help him or her to get the information he or she needs. It works without6 charges on like the telephones.

Two way wired intercom systems enables sound or speech to be transmitted in two directions, therefore enabling a conversation. Intercoms are generally compared of fixed microphone/speaker units which connect to a central control panel. In general, a communication system requires three things namely; a transmitter a propagation medium and a receiver. The information to be transferred may be in analog form (example, voice or audio) as in the case of this study where voice is the source of information, or in digital form (computer data, digitalized form and so on).

1.2 STATEMENT OF PROBLEM

In a business organization, shops, stores and stressful in relating/ delivering information between each other within a particular building. The servant finds it laborious going to the boss always whenever he /she has information to deliver or wants to carry out action(s) with respect to the master’s authority. Therefore, this project work is to address this issue, looking forward to eliminating the stressful manpower involved and to facilitate information delivery, making communication easier. The intercom system forming the basic of this study and designed to serve the HOD’s office and the secretary’s office for internal communication.

1.3 PURPOSE(1) The main objective of this project is to construct a two way wired intercom

that will help two persons or more to communicate with each other within a particular domain, like offices homes, warehouse e.t.c.

(2) To build a telephone that will transmit signal via a medium at no cost.(3) To immensely help the engineering students understand the technology

behind two way simple intercom and its practical development.

1.4 SIGNIFICANT OF THE STUDY

The design and construction of two way intercom system will help students or individual to understand the basic knowledge of intercommunication industries, also it’s a means to replace man’s labour and stress of walking over a given premises for information delivery. These station wired intercom system can be used as a door phone, connecting from the house to the door to screen visitors to the house. The wife, after preparing dinner, can through this system call on the husband in his bedroom to the dinner table. Generally, intercom system can be used for message broadcast (in case of multi-channel intercom), as door phone, monitoring etc.

1.5 SCOPE OF PROJECT

The scope of this project work design of simple two way intercom system is to limited to the design, construction and test on a two station simple intercom system with specification that;

I. The demodulator should operate with a minimum distortion while producing an adequate output

II. The small signal amplifier must provide an undistorted signal into the buffer amplifier to be able to drive a speaker of 8 ohms impedance.

III. A 9 volt d.c power supply is to be design and employed to power the simple intercom for operation at each station.

IV. Result shall fully be discussed while suggestions for further study made.

CHAPTER TWO

LITERATURE REVIEW

2.0 HISTORYThis chapter will emphasize on the research carried; intricate on ways in which this assist the design at end.

The audio amplifier which was converted into two way intercom was invented in 1959 by lee de forest when he invented the vacuum tube. The triode was a three terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio.Early audio amplifiers were based on vacuum tubes (also known as valves), and some of these achieved notably high quality (i.e the Williamson amplifier of 1747-9). Most modern audio amplifiers are based on solid state devices (transistors such as BJTs and MOSFETs), but there are still some who prefer tube-based amplifiers, due to a perceived ‘warmer’ valve sound. Audio amplifiers based on transistors became practical with the wide availability of inexpensive transistors in the late 1960s. Key design parameters for audio amplifiers are frequency response, gain, noise, and distortion.These are interdependent; increasing gain often leads to undesirable increases in noise and distortion. While negative feedback actually reduces the gain, it also reduces distortion. Most audio amplifiers are linear amplifiers operating in class AB (ONOH G.N 2005). Historically, the majority of commercial audio preamplifiers made had complex filter circuits for equalization and tone adjustment, due to the far from ideal quality of recordings, playback technology and speakers of the day. Using today’s high quality (often digital) source material, speakers,etc, such filter circuits are usually not needed. Audiophiles generally agree that filter circuits are to be avoided wherever possible today’s audiophile amplifiers do not have tone controls or filters.

Since modern digital devices, including CD and DVD players, radio receivers and tape decks already provide a “flat” signal at line level, the preamp. Is not needed other than as volume control. One alternative to a separate preamp is to simply use passive volume and switching controls, sometimes integrated into a power amp. To form an “integrated” amplifier. For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best valve amplifiers. This led audiophiles to believe that valve sound had an intrinsic quality due to the vacuum tube technology itself. In 1972, matti otala demonstrated the origin of a previously unobserved form of distortion: transitory intermodulation distortion (TIM),also calledslew rate distortion . TIM distortion was found to occur during very rapid increases in amplifier output voltage. TIM did not appear at steady state sine tone measurements, helping to hide it from design engineers prior to 1972. Problems with TIM distortion stem from reduced open loop frequency response of solid state amplifiers. Further works of otala and other authors found the solution for TIM distortion, including increasing slew rate, decreasing preamp frequency bandwidth, and the insertion of a lag compensation circuit in the input stage of the amplifier. In high quality modern amplifiers the open loop response is at least 20KHz,canceling TIM distortion . however, TIM distortion is still present in most low price home quality amplifiers. The next step in advanced design was the Baxandell Theorem, created by peter Baxandell in England.This theorem introduced the concept of comparing the ratio between the input distortion and the output of an audio amplifier. This new idea helped audio design engineers to better evaluate the distortion processes within an audio amplifier. Important applications include public address systems, theoriticaland concert sound reinforcement, and domestic sound systems.The sound card in a personal system contains several audio amplifiers (depending on number of channels), as does every stereo or home-theatre system.

2.1 BACKGROUND AND MATHEMATICAL THEORY OF THE WORK

The intercom system works in the principles of modulation demodulation (modem). This means that outside the power section of the system, there are basically two segments in the gadget viz. modulation segment and the demodulation segment (V,K Mehta,1998). Other sub parts include the input and output transducers, the transmission channel, the audio amplifier, the bias circuit, the trimmer circuit and the volume control.

The element microphone receive the signal which is the human voice and its frequency falls within a limited band of 300HZ to 3.4 KHz approximately and convert it into audio frequency voltage signal which is very small and has to be amplified. This design uses transistor Q1 which is 1800 phase shifted as microphone amplifier and the collector and its in-phase output taken at the emitter and mixed mixed by C3, C4, R7 and R8 network. R7 is timed until the two incoming signals almost cancel out. In this way, the loud speaker will reproduce a very faint copy of the signals picked-up the microphone. At the same time, as both collectors of the two interconnects are tried together, the 1800 phased-shifted signal will pass to the audio amplifier of the second unit will be attenuation so it will be loudly reproduced by its loud speaker.

The same operation will occur when speaking into the microphone of the second unit. The audio power amplifier used by the circuit is TDA2003 audio power amplifier IC which is capable of delivering about 1 wait of output power at a supply voltage comprised in the 6-12V range.

The loud speaker in this case is the receiver of the gadget which persons he work of converting the electrical energy into the original sound energy.

2.1.1 CALCULATION

Using Ohm’s law to determine the current and power in a circuit using the 8Ω speaker.

I = VR

Maximum output voltage = 12 (supply Voltage of the IC) of any amplifier circuit.

All the semiconductor in this project is powered using 6 Volts battery. This implies that:

Maximum output voltage of the audio IC = 12×6=3V

I = VR

I = 38= 0.375 Amps.

=VI

3 ×0.375 Amps=1.125watts .

CHAPTER THREE

CONSTRUCTION

3.0 DESIGN ,

Below are basic steps taken during the research and designing stages of this project;

Browsing the internet for relevant for relevant information on the project topic

Existing circuit diagrams sourced for Then studied and analysed the diagrams to arrive at our choice of dragram

which was based on simplicity, effectiveness and comprehensive Changes were made on the circuit to further ensure effectiveness. Some of

these changes included choice of microphone and speaker. Finally, arrived at the block below.I.1 component implementation

Using Ohms law to derive the component values used in the circuit by first principle by considering resistors in series (A.J Watkins 1983).

R1 + R2 + R3 ……….Rn

Considering the 9voilt that is needed to power the circuit and semiconductor was considered when the range of 9 volts and the maximum current is8mA.

Example, R = VI, 9 × 8 = 72KΩ, so every other component was chose having tested with the voltage and current mentioned above.

FIG 3.1 CIRCUIT DIAGRAM

FIG 3.2 BLOCKS DIAGRAM

3.4 PREPARING THE VEROBOARD

This work completed by using a veroboard to assemble the above explained electronic components. The process described below was taken, to prepare the veroboard.

Grab a very sharp carft knife and a ruler. On the track side of the board, count 40 complete holes along a track, then place the ruler perpendicular to the next hole and cut off the unwanted lines.

Now turn the board over, and repeat the operation in exactly the same place on the component side. Pick up the board and snap it with both hands, keeping your fingers close to the score mark on either side it should break evenly, leaving you with two rectangular pieces. Now (if the board is too wide) do the same thing again, but along the 40th track and score through the holes on that track. Do the same on the other side, then snap. If all went well, you should now have a piece of veroboard of the correct size- 39 tracks by 40 holes(onuha R.U 2011).

3.4.1 INSPECTING THE TRACKS

Very occasionally, a piece of veroboard will have defects such as small splashes of copper bridging adjacent tracks. Inspect the board carefully to make sure there are no bridges. If you do find any fault rn your knife between the tracks in other to cut it (onuha R.U 2011).

3.4.2 SOLDERING

Soldering is the process of making a sound electrical and mechanical joint between certain metals by joining them with a soft solder. This is low temperature melting point alloy of lead and tin. The joint is heated to the correct temperature by 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 “bits”, 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,

Good soldering is skill that is learnt by practice (T.G Francis 1988). The most important point in soldering is that both parts of the joint to be made must be at the same temperature. The solder will flow evenly and make a good electrical and mechanical point only if both parts of the joint are at an equal high temperature. Even though it appears that there is a metal to metal contact in a joint to be made, very often there exists a film of oxide on the surface that insulates the two parts. For this reason it is no good applying the soldering iron tip to one half of the joint only and expecting this to heat the other half on the joint as well

3.5 TESTING THE CIRCUIT

After the construction, the circuit was properly analyzed and short circuit and open were all corrected. The two circuit are the powered with a 220V ac supply with two persons holding the handset at two ends.

One of the person dial the other by pressing the ringer switch, the recipient at the other end picks his handset and full duplex communication took place.

The same process was repeated but this time recipient dialing the caller and clear communication was established.

At this point, it was concluded that there was no error and the project couple coupled and cased.

3.6 PRINCIPLE OF OPERARTION

The principal of operation of this work (Two-Way Wired Intercom) will be properly understood by taking the analysis of the stages that make up the entire system. Complete circuit is run on 6volts 4.5Ah battery (V.K MEHTA 1988). The battery is where all the sub circuit such as the audio amplifier and the tone turning on the switch, all the sub circuit will be set to receive power from the source as the phone handle is lifted up except the tone generator circuit which is powered immediately so that any tone received from UNIT 2 will be amplified to tell the user UNIT 1 that UNIT2 want to establish conversation. Any of the users will tell the second users that he wants to establish conservation by pressing the ringer button. This sends a

tone signal to the phone and conversation is successfully established when the users must have picked up the phone.

The handle of the phone is where the microphone (mouth piece) and the ear piece are located. Any sound or speech made by any o f the user is picked up by the microphone as mechanical vibration and converted to electrical signal that has a voltage frequency which its amplitude varies linearly with time (alternating), and a frequency which is a replica of the frequency of vibration. This electrical signal has low transistor (C1815) connected in active region. It is then sent to the power amplifier were the final amplification is made. The ear piece connected through a relay switch so that it is activated and deactivated by pressing the voice out switch. On dropping the phone, other sub circuits are deactivated leaving only the tone generator activated. The internal battery can be charged by charged by plugged the mains wire to socket and switching on the system.

3.6.1 INPUT SOURCE (MICROPHONE)

The input source contains the transducer which converts the sound (speech) in form of mechanical vibration to electrical signal. The electrical signal has a voltage which its amplitude varies linearly with time. The transducer in this block is a capacitor (condenser) microphone (Geoffrey E and Jan S 1989).

FIG 3.3

3.6.2 OUTPUT DEVICE (SPEAKER)

The basic aim of every telephony system is for one to successfully transmit or receive voice (speech) with minimum interference. This speech being an electrical signal which has a voltage of varying amplitude cannot be seen or understand the content by feeling, hence there must be a device which will reproduce the equivalent of the electrical signal being transmitted. This device is the speaker and

it does that by converting the electrical signal into mechanical vibration (diaphragm moving back and forth). The speaker contains basically the diaphragm, coil and magnet (A.K THERAJA 2003).

FIG 3.4

3.6.3 MEDIUM (FLEXIBHLE WIRE)

In every communication system, there must be a medium through which data is being sent or received. The medium includes; air/spaces as in electromagnetic wave, fiber optic cables as in laser beam and strands of copper cable as in electrical signal. The medium through which the data is being transmitted in this project is flexible wire. When a communication network is established, user 1 talks to the microphone on his headset and user 2 hears it from the speaker on his own headset and vice versa. I.e. the voice at one terminal is amplified and sent through the medium to a speaker at the other terminal. Because this is a full duplex kind of hear simultaneously.

CHAPTER FOUR

4.1 DATA PRESENTATION AND ANALYSIS

Using ohm’s (Ω) law to determine the current that flows through each of the resistors in the circuit in the both sub-circuit.

Assuming different voltages passed through each of the resistor, from 12-6v.

I = V/R = ……………………………….(4.1)

I1 = 12

47,000 = 2mA ……………………...(4.2)

I2 = 11

330,00 = 3mA …………………..…..(4.3

I3 = 10

2200 = 4mA …………………..…...(4.4)

I4 = 9

220,00 = 4mA ………………….…..(4.5)

I5 = 8

100,00 = 8mA ……………………..(4.6)

I6 = 7

300,00 = 2mA ……………………..(4.7)

I7 = 6

330,00 = ImA ……………………..(4.8)

Total current passing through the resistors.

I1 + I 2 +I3+ I4 +I5 +16 = (……………………(4.9)

2 + 3 + 4 + 4 + 8 +2 + 1= 24mA

4.2 CURRENT VARIATIONS IN SRESISTORS

S/N V(DC) I(MA) R(Ω)1 12 2 47,0002 11 3 22003 10 4 220,0004 9 4 220,0005 8 8 1000,0006 7 2 330,0007 6 1 330,000

The table 1.4 show above, is used in describe the current variation in the different resistors the circuit which show in table 4.1 that the value of the resistor determine the amount of current through the resistor with respect to input voltage in the circuit.

Fig4,1. Circuit diagram of the ringer

IV.1 TONE GENERATOR

The diagram of fig.4.1 is a diagram of the ringer that generates the ringing tone of the intercom. Ringing tone is an audio tone that signal the user of one of the two phones (e.g. unit 1) that the other user (unit2) wants to establish a conversation in the network. The process of generating the ringing tone involves researching on the datasheet of top semiconductor manufacturers, to get a suitable IC (intergraded circuit) for it. The semiconductor guide of Toshiba shows that the popular timer IC NE555 is suitable since it can connected to function as an stable multivibration to generate an audio frequency tone of 450HZ. The pin out of IC and are test circuit is as shown below.

Fig. 4.3 APPLICATION CIRCUIT FOR THE 555 TIMER

The 555 monolithic timing circuit is a highly stable controller capable of producing accurate time delays, or oscillation. In the time delay mode of operation, the time is precisely controlled by external resistors (RA and RB) and capacitor( C)

For a stable operation as an oscillator, the free running with two external resistor and one waveforms and the output structure can source or sink up to 200mA

specification from producer shows that the IC operates at a voltage range of 5 to 15 volts (Geoffery E Lewis 1989).

4.4 CALCULATION

The frequency of oscillation is caculcate by using the formula below.

T1 = Time of ON = 0.693 (Ra+Rb)C

T2 = Time of OFF=0.693(Rb)C

Total time(T)=T1+T2

From the above expression, one can easily compute the frequency since it is the inverse of time .hence F =1/T(hertz).

T1= 0.693(1000+2(15000)×100×10-9………………………………………(4.10)

T2=2.1483×10-3……………………………………………………………..(4.11)

F=1/2.1483×10-3……………………………………………………………..(4.12)

=465.48 ∞ 465Hz

The frequency of the oscillator is set to 465 hertz by using 1000 ohm as the Ra and 15000 ohms as Rb and 100 nanofarad as C.

AUDIO AMPLIFIER

In the fig. 4.4, electrical signal from the transducer (microphone) is considerably little to be fed directly to the speaker. Moreover when electrical signal is being transmitted over a long distance it degrades as it goes through the medium. Calls for the introduction of an amplifier in this project. The amplifier section of this work is built with popular low power consumption audio amplifier IC (TDA2003) from Toshiba Semiconductors. The IC is not suitable for the work (Two way wired Intercom) because of its low idle power consumption.

TABLE 4.2 BILL OF QUANTITY AND EVALUATION (BEME)

S/N COMPONENT QUANTITY (X2)

INDIVDUAL PRICE(N)

AMOUNT (N)

1 NE555 Timer IC

3 100 300

2 CI815 transistor 3 40 1203 6Ω speaker 2 300 6004 IN4001 Diode 4 10 205 47Ω 1 10 206 330KΩ 1 30 207 2200KΩ 2 10 408 2200kΩ 1 10 209 100kΩ 1 10 2010 100uf 2 10 4011 10nf 4 20 16012 TDA Audio

Amplifer1 400 400

13 12Ω Speaker 2 200 40014 47µf(Electrolyt

e Capacitor)1 30 60

15 10nf 1 20 4016 220nf 1 20 4017 1µf 1 20 4018 50kΩ Variable

Resistor3 40 120

19 carbon 2 500 100020 Microphone 2 400 80021 Battery 1 600 1200

22 Packaging 2 700 2800Total=8,260

CHAPTER FIVE

CONCLUSION AND RECOMMENDATION

5.1 LIMITATION OF THE STUDY

This work has encountered so many limitations just like any common but advanced design, which includes;

II. This circuit is based upon theoretical calculations and may require practical changes to be made while implementing the circuit in hardware.

III. This is designed for loudspeaker with low range and hence cannot be used at large buildings.

IV. The most challenging is that of access to materials, for building the project work.

5.2 CONCLUSION

It shall sound insolvent to say that the this project was achieved at a platter of gold. The success of this work is a dividend of careful research, practical and commitment; also it is a guarantee of a sound knowledge of electronics component and its implementation in communication.

During the execution of this project, more knowledge were acquired which if this kind of work is made a constant practice, the sky will be limit in the field of electrical electronics, particularly communication and electronic option.

When much problem was encountered in this work was on the purchase of the component since it was costly and some were even purchased at lagos at an additional transportation cost which increased the production cost. Considering this, if the component purchases are made in bulk from the producer, this selection of the trimmer for effective impedance matching at the output of the one unit input

of the second unit after the encountering such a difficulty. In addition , if a screen cable cannot be used, a power line carrier communication can be engaged as the transmission medium between the two spots where he PHCN wire cable can be used as the medium for communications and this will reduce the product cost.

To cost this system for large industrial premises of other large premises, a multiplexer control unit with PC is incorporated to the system. Other technologies associated to the system is the wireless where electromagnetic waves that carries the information signal will be transtmitted through the air using an RF terminal and convert it back to the original information through decoder. This technology though costly but will make the intercom system more reliable and fixable just like the handest. We belief that more research shall yield more innovation on this technology to really make it stand the test of time.

5.2 RECOMMENDATION

Careful research and analysis has revealed the relevance of intercom system in the various fact of our society. The importance of this facilities t human Endeavour has outsmart the cost of it production because the implementation of this technology will go along way to save cost in the world of information management, just like as the GSM technology is doing today. The relevance of this technology ranges from domestic home utility (toilet, kitched, bedroom, door gates etc) industrial premise untility, security services utility, public service utility and many more. It is rather unfortunate that the public has not gotten the orientation on the utility of this diversified utility gadget due to the presence of the GS,M supplement. The good news about intercom system is that it is not cost intensive to installed, it has no service cost attachment.

The cost involvement in this project actualization can be reduced by employing the principal of mass production where component will be imported from the production company in mass quantity and the gadget also produced in mass quantity with different designs particularly in a reduced size.

There should also be such intercom system between the school security units and the students both in the lecture halls and school hotels should emergency calls both securities of live and properties.

Our young engineering technocrats, government, NGO, financial houses to join hands together and advance this country technologically by encouraging local technology.