CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Remote control facilitates the operation of regulators around the home or office

from a distance. It provides a system that is simple to understand and also to

operate, a system that would be cheap and affordable, a reliable and easy to

maintain system of remote control and durable system irrespective of usage. It adds

more comfort to everyday living by removing the inconvenience of having to move

around to operate a fan regulator. The system seeks to develop a system that is cost

effective while not under mining the need for efficiency. The first remote control,

called “lazy bones” was developed in 1950 by Zenith Design and Construction of a

Remote Controlled Fan Regulator. The device was developed quickly, and it was

called “Zenith space command”, the remote went into production in the fall of

1956, becoming the first practical wireless remote control device. Today, remote

control is a standard on other consumer electronic products, including VCRs, cable

and satellite boxes, digital video disc players and home audio players. In year

2000, more than 99 per cent of all TV set and 100 per cent of all VCR and DVD

players sold are equipped with remote controls. The average individual these days

probably picks up a remote control at least once or twice a day. Basically, a remote

1
control works in the following manner. When a button is pressed it completes a

specific connection which produces a signal specific to that button. The transistor

amplifies the signal and sends it to the LED which translates the signal into

infrared light. The sensor on the appliance detects the infrared light and reacts

appropriately. The remote control’s function is to wait for the user to press a key

and then translate that into infrared light signals that are received by the receiving

appliance. The carrier frequency of such infrared signals is typically around 36

kHz. Usually, the transmitter part is constructed so that the transmitter oscillator

which drives the infrared transmitter LED can be turned on/off by applying a TTL

(transistor-transistor logic) voltage on the modulation Controlled input. On the

receiver side, a photo transistor or photodiode takes up the signals. The approach

used in this work is the modular approach where the overall design was broken

into functional block diagrams, where each block in the diagram represents a

section of the circuit that carries out a specific function.

1.2 STATEMENT OF THE PROBLEM

The advent of sophisticated device and various home appliances, it is economical

to bring about the ease to operating the various desired home appliances, as to add

more comfort to everyday living by removing the inconvenience of having to move

around to operate a fan regulator. The system seeks to develop a system that is less

cost implicative while not under mining the need for efficiency, with
2
advancements in modern technology in mind, the design seeks to reduce stress in

operation of the electric fan through working quiet a distance to the regulator.

1.3 OBJECTIVES OF THE STUDY

The aim of this project work is to design and construct a remote control of four

speed regulator for a fan with the following objectives;

1. To design an electrical circuit for a remote control four speed fan regulator.

2. To construct an operational four speed remote controlled regulator for a fan

using electrical components.

3. To study the operation of a four speed remote controlled regulator for a fan

4. To endeavor that the design delivers the best product or the most efficient

service at the lowest cost to the end user.

1.4 PURPOSE OF THE STUDY

The purpose of the project is to ease regulating fan regulator based on the speed

desired by designing and constructing a remote controlled four speed fan regulator

for use both in the home and out-door using a remote control.

3
1.5 SIGNIFICANCE OF THE STUDY

The significance of this project work is as follows;

1. The remote control device sends an infra-red beam, which is received by the

infra-red sensor on the regulator and the speed of the fan is increased thereby

reducing the stress in regulating the fan speed especially by aged

individuals.

2. The project work creates an improvement in the long history of fan

regulators with the use of the remote controlled method of regulating its

speed during operation.

3. The project provides a cheap, affordable, reliable and easy to maintain

system of remote control and durable system irrespective of usage.

1.6 SCOPE OF THE STUDY

The scope of this project work covers the designing of an operational circuit that is

capable of regulating a four speed fan regulator using remote controlled

mechanism and the construction of the design using locally available electrical

components. The use of some known discrete components is employed in the

circuit design in achieving this great feat.

4
1.7 LIMITATIONS OF THE STUDY

The limitations that were encountered during the design of the project work

include:

 The unavailability of certain components within our reach.

 The frequent burn out of the infra – red device due its sensitivity to

temperature.

 Difficulties in the soldering process

 Complexity in the design procedure

1.8 DEFINITION OF TERMS

1. REMOTE: Denoting a device which can only be accessed by means of a

network.

2. SPEED: The rate at which something (in this case the fan blades) moves or

operates.

3. REGULATOR: A thing that controls the action of an electrical appliance.

4. CONTROL: To determine the behaviour or supervise the running or

operation of an electrical equipment or appliance.

5
 CHAPTER TWO

LITERATURE REVIEW

2.1 PROJECT HISTORY

Pictorial records show some of the earliest fans date from around 3000 BC and

there is evidence that the Greeks, Etruscans and Romans all used fans as cooling

and ceremonial devices, while Chinese literary sources associate the fan with

ancient mythical and historical characters.

Early fans were all of the fixed type, and the folding fan does not appear either in

the East or the West until relatively late in its history.

The first European folding fans were inspired by and copied from prototypes

brought in to Europe by merchant traders and the religious orders that had set up

colonies along the coasts of China and even Japan. These early fans were reserved

for Royalty and the nobility and, as expensive toys; they were regarded as a status

symbol.

In recent times, the electric fan is no longer a “must have” accessory as it used.

With advancements in modern technology, the fan has different applications in

terms of regulating ranging from the ceiling fan to the remote controlled or

rechargeable fans. This project work seeks to dive further into the many diverse

6
fan regulator schemes to design and construct an operational and affordable four

speed remote controlled fan regulator for both industrial and domestic use.

In 1956, Robert Adler developed “Zenith Space Command” a wireless remote

device that operates mechanically by a simple push of a button on the remote

control. The inventions of various kind of transistor have made it easier in building

complex circuits like this.

2.2 COMPONENT FOR THE FAN REGULATOR

The various components were used in the cause of the design and implementation

of the project work, with their various ratings shown on table 1:

 Transformer

 Power diodes

 Capacitor

 Resistor

 Zener diode

 Transistor

 Voltage regulator

 Infra-red

 Light emitting diode

 Fan
7
  Decade counter

 Relay

 Switch

 Oscillator

The various values of the used components are as shown in the specification

table in chapter three.

2.3 REMOTE CONTROL DEVICE OPERATION

The remote control device has the task of sending the infra-red signal, which is

received by the infra-red sensor. It’s mode of operation can be better understood

through the circuit diagram. Circuit of remote device At the application of voltage

from the 9v battery or when the single switch is closed, the 4060B oscillator IC,

produce high and low signals on pin 6, which is feed across the base of the NPN

transistor. When the output from the oscillator is high, there is a high voltage

across the base of the NPN transistor, which turns it on. This permits the infrared

emitting diode to be grounded, resulting in the emission of an infra-red ray. When

the output from the oscillator is low, there is a low voltage across the base of the

NPN transistor, which turns off the switching transistor, resulting in no emission of

any infra-red ray from the infra-red emitting diode. The 4060B oscillator IC

produces a stream ofpulses at a frequency determined by the RC configuration.

8
The pulse is connected to the base of the switching transistor through a

1kΩresistor. The pulse determines frequency on the infra-red beam, such that it’s

detection by the sampler would be possible.

RELAY (CONTACTOR)

A relay is an electrically operated switch that uses an electromechanical operation.

Relays are used where it is necessary to control a circuit by a low-power signal

(with complete electrical isolation between control and controlled circuits), or

where several circuits must be controlled by one signal. The first relays were used

in long distance telegraph circuits as amplifiers: they repeated the signal coming in

from one circuit and re-transmitted it on another circuit. Relays were used

extensively in telephone exchanges and early computers to perform logical

operations. A type of relay that can handle the high power required to directly

control an electric motor or other loads is called a contactor. Solid-state relays

control power circuits with no moving parts, instead using a semiconductor device

to perform switching. Relays with calibrated operating characteristics and

sometimes multiple operating coils are used to protect electrical circuits from

overload or faults; in modern electric power systems these functions are performed

by the use of digital instruments called protective relays. Because relays are much

more resistant than semiconductors to nuclear radiation, they are widely used in

safety-critical logic, such as the control panels of radioactive waste-handling

9
machinery. Electromechanical protective relays are used to detect overload and

other faults on electrical lines by opening and closing circuit breakers.

The use of relays for the logical control of complex switching systems like

telephone exchanges was studied by Claude Shannon, who formalized the

application of Boolean algebra to relay circuit design in A Symbolic Analysis of

Relay and Switching Circuits. Relays can perform the basic operations of Boolean

combinatorial logic. For example, the boolean AND function is realised by

connecting normally open relay contacts in series, the OR function by connecting

normally open contacts in parallel. Inversion of a logical input can be done with a

normally closed contact. Relays were used for control of automated systems for

machine tools and production lines. The Ladder programming language is often

used for designing relay logic networks. Relays are used wherever it is necessary

to control a high power or high voltage circuit with a low power circuit. The first

application of relays was in long telegraph systems, where the weak signal

received at an intermediate station could control a contact, regenerating the signal

for further transmission. High-voltage or high-current devices can be controlled

with small, low voltage wiring and pilots switches. Operators can be isolated from

the high voltage circuit. Low power devices such as microprocessors can drive

relays to control electrical loads beyond their direct drive capability. In an

10
automobile, a starter relay allows the high current of the cranking motor to be

controlled with small wiring and contacts in the ignition key.

RESISTOR

A resistor is a passive two-terminal electrical component that implements electrical

resistance as a circuit element. Resistors act to reduce current flow, and, at the

same time, act to lower voltage levels within circuits. In electronic circuits,

resistors are used to limit current flow, to adjust signal levels, bias active elements,

and terminate transmission lines among other uses. High-power resistors that can

dissipate many watts of electrical power as heat may be used as part of motor

controls, in power distribution systems, or as test loads for generators. Fixed

resistors have resistances that only change slightly with temperature, time or

operating voltage. Variable resistors can be used to adjust circuit elements (such as

a volume control or a lamp dimmer), or as sensing devices for heat, light,

humidity, force, or chemical activity. Resistors are common elements of electrical

networks and electronic circuits and are ubiquitous in electronic equipment.

Practical resistors as discrete components can be composed of various compounds

and forms. Resistors are also implemented within integrated circuits. The electrical

function of a resistor is specified by its resistance: common commercial resistors

are manufactured over a range of more than nine orders of magnitude. The nominal

value of the resistance will fall within a manufacturing tolerance.

11
TRANSISTOR (NPN TYPE)

This project work made use of the common emitter configuration (CE) using the

NPN types of transistor, in which input signal is usually applied between the base

and emitter, while the output signal is taken from the collector and emitter circuit.

Where IB is the input current, IC is the collector current, the ratio of the d.c

collector current to the d.c base current is represented by βdc. A transistor is a

semiconductor device used to amplify and switch electronic signals and electrical

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

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

transistor's terminals changes the current through another pair of terminals.

Because the controlled (output) power can be higher than the controlling (input)

power, a transistor can amplify a signal. In an n–p–n transistor operating in the

active region, the emitter–base junction is forward biased (electrons and holes

recombine at the junction), and electrons are injected into the base region. Because

the base is narrow, most of these electrons will diffuse into the reverse-biased

(electrons and holes are formed at, and move away from the junction) base–

collector junction and be swept into the collector; perhaps one-hundredth of the

electrons will recombine in the base, which is the dominant mechanism in the base

current. By controlling the number of electrons that can leave the base, the number

12
of electrons entering the collector can be controlled. Collector current is

approximately β (common-emitter current gain) times the base current.

2.4 REGULATOR SENSOR DETECTION

Infra-red sensor and signal amplifier. The signal from the infra-red transmitter is

sent to an infra-red sensor. The sensor converts the infra-red energy into

corresponding electric current. The four stage NPN transistor amplifiers boost the

intensity of the signal to a reasonable level. The output is fed out to a connected

RC filter. Such that any reasonable distortion is simple is simply removed from the

signal. The relay is designed to switch off for some time after the signal has being

sampled by the sampler. The cutoff technique eliminates any distortion or errors

coming along with the transmitted signal.

2.5 DESCRIPTION OF A DECADE COUNTER OPEATION

The fan regulator system works on the principle of sequential counter of the

integrated circuit, such that when the regulating button is pressed, the sequential

switching of the counter I.C regulates a particular regulator speed, this continuous

in sequence as long as the button is pressed.

13
2.6 APPLICATION OF REMOTE CONTROLLED FAN RRGULATOR

The applications of a remote controlled fan regulator are as follows;

1. Remote controlled Fan Regulator is used to control the speed of fan from our

bed or couch.

2. The same circuit finds its use to control the Intensity of light at various

levels.

3. This circuit also finds it use for switching ON and OFF any electronic

circuit.

14
 CHAPTER THREE

METHODOLOGY

3.1 DESIGN AND CONSTRUCTION

POWER SUPPLY: The transformer is a 220/12V with a filter capacitor (2200µF/

25V) and a 5V regulator. The relays are supplied by a 12V supply from the

rectifier. And the regulated 5v supply from the 7805 is used for the main circuit.

Fig 1.0 Symbol of Transformer

ANALYSIS OF THE RECTIFIER

The full wave rectifier has 4 diodes connected in two cycles which include; the

positive half cycle and the negative half cycle. In the positive half cycles two

15
diodes say D3 and D4 are forward biased and conduct, while the remaining two

diodes D1 and D2 are reverse biased and behave as open circuits. During negative

half cycle, diodes D1 and D2 are forward biased and conduct while D3 and D4 are

reverse biased and behave as open circuits. As shown in the diagram below

showing the bridge rectifier. As we all know that the main function of rectifier is to

convert alternating input supply to D.C. which will be used to charge the battery

and then fed to regulator circuit.

Figure 2: Bridge Rectifier

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

constant voltage level. IC 7809 is used here. It is a 9V regulator. It regulates the

rectified 12V to 9V. This 9V is supplied to the whole circuit.

16
3.2 DESIGN SPECIFICATION

S/N COMPONENT DESCRIPTION COMPONENT RATINGS

1 TRANSFORMER 220V a.c to 12V d.c

2 POWER DIODES N4001 Rectifying diodes

3 CAPACITOR 470µF, ELECTROLYTIC

4 RESISTOR 1KΩ, 10KΩ,2KΩ, 100Ω, 47KΩ

5 ZENER DIODE 5watts, 12v

6 TRANSISTOR NPN, β= 50, IC= 250Ma

7 VOLTAGE REGULATOR IC7812

8 INFRA-RED TSOP1738

9 LIGHT EMITTING DIODE Multipurpose

10 FAN Regular fan

11 DECADE COUNTER IC4017

12 RELAY Relay A, Relay B, Relay C, Relay D

13 SWITCH SW

14 OSCILLATOR Crystal pixel

17
3.3 DESIGN MATERIALS AND COST

S/N COMPONENT PER UNIT QUANTITY AMOUNT

DESCRIPTION PRICE

1 TRANSFORMER 400 1 400

2 POWER DIODES 50 4 200

3 CAPACITOR 200 5 1000

4 RESISTOR 20 6 120

5 ZENER DIODE 50 1 50

6 TRANSISTOR 150 2 300

7 VOLTAGE REGULATOR 250 1 250

8 INFRA-RED 400 1 400

9 LIGHT EMITTING DIODE 100 1 100

10 FAN 3,500 1 3,500

11 DECADE COUNTER 500 1 500

12 RELAY 250 4 1000

13 SWITCH 150 1 150

14 OSCILLATOR 300 1 300

15 TOTAL 8270.00

18
3.4 BLOCK DIAGRAM
REMOTE
CONTROLLED UNIT

VOLTAGE
TRANSFORMER RECTIFYING UNIT RECEIVING SENSOR
REGULATOR UNIT

OUTPUT UNIT DRIVER UNIT DECADE COUNTER AMPLIFIER UNIT

(LOAD) UNIT

3.5 CIRCUIT DIAGRAM

Circuit diagram

19
3.6 WORKING PRINCIPLE THE REMOTE FAN REGULATOR

The button feeds the preamplifier such that it sends signals from the remote

controlled unit to the receiver power amplifiers. This amplifies the input signals to

an adequate transmitter line level. In view of the above, one can now say that the

remote fan regulator system is an electronic amplification system used for

regulation. It usually sends its signal using a small transmitter to a nearby receiver

connected to the system, but it can also use infrared light if the transmitter and

receiver are within sign of each other. The transmitter is responsible for taking in

the signal from the remote control device and transmitting it to the receiver using

radio waves. The sensitive transducer element of a microphone is called its

element. Since a wireless microphone is used in this project; a wireless microphone

is one in which communication is not limited by a cable. It usually sends its signal

using a small FM radio transmitter to a nearby receiver connected to the sound

system, but it can also use infrared light if the transmitter and receiver are within

sign of each other. The transmitter is responsible for taking in the signal from the

microphone, modulating it, and transmitting it to the receiver using radio waves.

20
 3.7 DESIGN CALCULATIONS

Pinout diagram

The connection of the pins for a DIP package is as follows:

Pin Name Purpose

1 GND Ground reference voltage, low level (0 V)

2 TRIG The OUT pin goes high and a timing interval starts when this

input falls below 1/2 of CTRL voltage (which is typically 1/3

VCC, CTRL being 2/3 VCC by default if CTRL is left open).

3 OUT This output is driven to approximately 1.7 V below +VCC, or to

GND.

21
4 RESET A timing interval may be reset by driving this input to GND, but

the timing does not begin again until RESET rises above

approximately 0.7 volts. Overrides TRIG which overrides THR.

5 CTRL Provides "control" access to the internal voltage divider (by

default, 2/3 VCC).

6 THR The timing (OUT high) interval ends when the voltage at THR

("threshold") is greater than that at CTRL (2/3 VCC if CTRL is

open).

7 DIS Open collector output which may discharge a capacitor between

intervals. In phase with output.

8 VCC Positive supply voltage, which is usually between 3 and 15 V

depending on the variation.

Pin 5 is also sometimes called the CONTROL VOLTAGE pin. By applying a

voltage to the CONTROL VOLTAGE input one can alter the timing characteristics

of the device. In most applications, the CONTROL VOLTAGE input is not used. It

is usual to connect a 10 nF capacitor between pin 5 and 0 V to prevent interference.

The CONTROL VOLTAGE input can be used to build an astable multivibrator

with a frequency-modulated output.

22
 Schematic of a 555 in bistable mode

In bistable (Schmitt trigger) mode, the 555 timer acts as a basic flip-flop. The

trigger and reset inputs (pins 2 and 4 respectively on a 555) are held high via

pull-up resistors while the threshold input (pin 6) is simply floating. Thus

configured, pulling the trigger momentarily to ground acts as a 'set' and

transitions the output pin (pin 3) to Vcc (high state). Pulling the reset input to

ground acts as a 'reset' and transitions the output pin to ground (low state). No

timing capacitors are required in a bistable configuration. Pin 5 (control

voltage) is connected to ground via a small-value capacitor (usually 0.01 to 0.1

μF). Pin 7 (discharge) is left floating.

23
 The output pulse ends when the voltage on the capacitor equals 2/3 of the

supply voltage. The output pulse width can be lengthened or shortened to the

need of the specific application by adjusting the values of R and C.

The output pulse width of time t, which is the time it takes to charge C to 2/3 of the

supply voltage.

These specifications apply to the NE555. Other 555 timers can have different

specifications depending on the grade.

SPECIFICATION BASE ON DATA SHEET

MAXIMUM RATINGS (TA = 25°C unless otherwise noted, common for Q1 and

Q2, − minus sign for Q1 (PNP) omitted)

THERMAL CHARACTERISTICS

24
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings

are stress ratings only. Functional operation above the Recommended Operating

Conditions is not implied. Extended exposure to stresses above the Recommended

Operating Conditions may affect device reliability.

DESIGN ANALYSIS FOR THE SWITCHING TRANSISTORS

Transformer rating from the manufacturer’s data book (specification), referring to

the circuit diagram;

VCEO = 50V

VCBO = 50V

VEBO = 50V

IC = 100mA

PD = VCEIC

PD = 50 × 100mA = 5000Mw
𝑉𝑐𝑐𝑅2
VR2 =
𝑅1+𝑅2

9 𝑋 10 90
VR2 = = = 6.0v
5+10 15

Taking base emitter loop,

VB – VEE - VBE = 0

Where VEE = IERE

VB - IERE - VBE = 0

25
Recall;

IE = IB + IC

IC = (β + 1)IB and,

IC = βIB, where β = 50
𝑉𝐵 − 𝑉𝐵𝐸 6−0.7
IB = = = 0.0113Ω = 104µA.
(β+1)𝐼𝐵 (50+1)1𝐾Ω

IC = βIB = 50x 104µA = 5.2mA

IE= approximate IC = 5.2mA

VCe - VCC - VC = 0

Where ICRC

VCe = ICRC - VC

VCe = (5.2 x 2,000) – 0.7 = 9.7V

25𝑚𝑉 25
re = = = 4.8Ω
𝐼𝐸𝑚𝐴 5.2

rin = re||RE = 4.8||1K Ω = 0.83Ω

𝑅𝑙 2𝑘Ω
the gain of the transistor = Av = = = 2409
𝑟𝑖𝑛 0.83Ω

𝑉𝑆
note the input voltage of the system is Vin = = approximately rin
𝑟𝑖𝑛

therefore Vin = Ierin = 5.2 x 0.83 = 4.3mV

Vout = IcRL = βIBRL = 50 x 104µA x 5= 26mV

26
 CHAPTER FOUR

ANALYSIS AND TESTS

4.1 WORKING OPERATION OF THE REMOTE CONTROLLED FAN

The fan is powered ‘ON’ and subsequently regulated by the remote control device.

The different four speed level of the fan is regulated through the use of infra – red

control by pressing the switch button which sends signal to the sequential decade

counter which in turn sends signals to the driver unit which initiate the control of

the fan movement. In this design, the remote control fan regulator has only one

button for the control as against having four different buttons, nevertheless, the

single button works in sequential manner in which successive pressing of the

button indicates the various level of the speed drive of the fan.

4.2 RELIABILITYAND TEST

The construction was tested block by block; the measurement of capacitance,

current, resistances and voltage were taken and compared with design values. To

operate the circuit, the switch, is held down while pointing the LED at the receiver.

The aim is to design a remote control that is portable in size and a receiver that

responds only to the infra-red signal transmitted by the remote control. The system

responds favourable and automatically changes the fan speed. The receiver-

transmitter maximum distance is approximately 10m; this is the range of the

27
transmission of the infra-red diode used. It was noted that the receiver unit was

able to receive signal propagated of the distance within the range.

4.3 PROBLEMS/TROUBLESHOOTING

The problem associated with the design is in the area of the proximity to operation

of the device, and since the device uses infra – red signal; its line of sight should

always be free of blockage.

4.4 MAINTENANCE GUIDE

For maximum use of the designed system, the sequential counter device should be

very effective in infra-red communication, the line of sight of the infra-red device

and its receiver should through. The 555 timer circuit should be a very high

precision. The remote control should be handled with care as to avoid

malfunctioning. The relay used should be of the required current rating.

4.5 PRECAUTIONARY MEASURES

The device should always be referred to an expert when problem is encountered.

The operator should know that this is a prototype of a remote controlled fan

regulator as not to expect 100% efficiency.

28
 CHAPTER FIVE

RECOMMENDATION AND CONCLUSION

5.1 RECOMMENDATION

The remote controlled fan regulator was developed using infra-red. This posed its

difficulties and gave certain limitation i.e. the infra-red sensor could not filter out

surrounding bright light. Engineers trying to improve on this should work towards

perfectly filtering out bright light so that only the infra-red rays are incident on the

infra-red sensor. The power supply could be improved, where a step-down would

not be used, thereby reducing the entire size of the project. Similarly, micro

soldering could also be used in order to further reduce the size of the equipment.

5.2 CONCLUSION

One of the primary objectives of an engineer is to endeavour to deliver the best

product or the most efficient services at the lowest cost to the end user. The system

has being tested and was found to meet the expected results. The aim of this work

was to design and construct a remote control for a fan regulator, and the system has

thus accomplished that. The remote control device sends an infra-red beam, which

is received by the infra-red sensor on the regulator, the display on the regulator

indicates a change in fan speed and the fan also increases in speed. The same

circuit finds its use in many more applications. By this the intensity of light can be
29
controlled using a remote. The intensity of light can be controlled in five levels

from off position to maximum intensity possible. So it finds use as a night lamp by

keeping the intensity of lamp in low level. Our normal T.V remote can be used for

all these purposes. So it is very useful or a real help to old age and sick people,

since they can control the speed from the place where they are sitting. We feel that

our product serves something good to this world and we like to present it before

this prosperous world.

30
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1. Howstuffworks [Internet]; ©1998-2006 How Stuff Works, Available at:

http://www.howstuffworks.com.

2. Datasheet Search System [Internet]; ©2003-2006 Alldatasheet.com,

Available at: http://www.alldatasheet.com.

3. Forrest M. Mims III, Engineer’s Mini Notebook, Volume I. Timer, Op Amp

& Optoelectronic Circuits & Projects, 1St Ed., Master

Publishing, 1986.

4. Theraja B.L., Theraja A.K., A text book of electrical technology, Ed. 21st

Publisher; Publication of division of Nirja construction and

Development co., Ltd. Ram Nagar., 1994.

5. Horowitz P., Hill W., The art of Electronics, 2nd Ed., Cambridge University

Press, U.S.A., 1995.

6. Amos S.W., James M. Principles of transistor circuit: Introduction to the

Design of Amplifiers, Receivers and Digital Circuits, 6th Ed.,

Hartnolls Ltd., 1981.

31