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1. Council for Technical Education and Vocational Training (CTEVT)
“Temperature controlDC fan”
Final Year Project Report2074
Submitted To:
Department of Electrical and Electronics
PreparedBy:
Bet Thapa 071EE03
Muna Bhusal 071EE12
Pawan Lamsal 071EE15
Prakash Kharel 071EE16
Anisha Neupane 071EE01
Bhuwan Chhetri 071EE04

2. COUNCIL FOR TECHNICAL EDUCATION AND VOCATIONAL TRAINING
KOREA NEPAL INSTITUTE OF TECHNOLOGY
Butwal -12, Tamnagar, Rupandehi
Department of Electrical and Electronics
The undersigned certify that they have read and recommended to council for Technical
Education and Vocational Training for acceptance, a project entitled “TEMPERATURE
CONTROL DC FAN”, Submitted by “ BET THAPA,MUNA BHUSAL,PAWAN
LAMSAL,PRAKASH KHAREL,ANISHA NEUPANE,BHUWAN CHHETRI”, on practical
fulfillment of the requirements for the Diploma in Electrical and Electronics engineering.
………………….. ………………….
Er. Arbind Kumar Chaudhary Er. Kiran Kafle
Office Chief Head of Department
Korea Nepal Institute of Technology E&E
………………….. ………………….
Internal Examiner External Examiner

3. COUNCIL FOR TECHNICAL EDUCATION AND VOCATIONAL TRAINING
KOREA NEPAL INSTITUTE OF TECHNOLOGY
Butwal -12, Tamnagar, Rupandehi
Department of Electrical and Electronics
The report entitled “TEMPERATURE CONTROL DC FAN” has been prepared by “BET
THAPA, MUNA BHUSAL, PAWAN LAMSAL, PRAKASH KHAREL, ANISHA NEUPANE,
BHUWAN CHHETRI” under my supervision and guidance. We hear by forward this for final
evaluation and approval.
…………………..
Er. Bharat Nepal
Project Guide
Department of Electrical and Electronics
KOREA NEPAL INSTITUTE OF TECHNOLOGY

4. ACKNOWLEDGEMENT
It’s a great pleasure in presenting this report as the requirement for the
achievement of Diploma programed under CTEVT (Council for Technical
Education and Vocational Training) for the practical fulfilment of Industry Based
MajorProject. CTEVT has introduced report writing in their courseto have
knowledge for the student. So, it is written from the Industry Based Major Project
group of Electrical and Electronics students for the practice in writing report which
helps the students in the further Bachelor program.
This report writing is would not have been possible without the guidance and
inspiration of our honorable Instructors and friends. First of all we would like to
thanks to our project guide Er. Bharat Nepal for the guidance and supervising our
project from his valuable lecture, instructing how to go ahead in diploma level
project and in the field of project to find desired output. We would also like to
thank to all our instructors and whole team of Korea Nepal Institute of technology.
Especially, Electrical and Electronic Department, Department Head Er. Kiran
Kafle.

5. Abstract:
With the aid of newer advance technological inventions days are growing complex
comparatively as well as the time is growing shorter. In the meantime, Automatic temperature
control DC fan has been a great subject of interest.
This project is about how the speed of a fan can be controlled, based on
temperature sensor. It is also a part of smart home application where the fan will gradually
increase its speed if the temperature is increasing. In general, home appliance fans need to be
operated manually with the help of regulators with the variation of temperature, thus requires a
repeatedly extra effort for regulating the fan speed which acts to our agony. So as to reduce this
extra effort and to add comfort, it is intended in this paper designing “Temperature Controlled
Fan”. In this project the main intension to control the fan by heating the sensor, i.e. the LM35,
where the speed of the fan is dependent and controlled by any device’s temperature like PC. As
the temperature of the device increases or decreases, the speed of fan increases or decreases
respectively. So it can be used mainly as a cooling device. By modifying the circuit slightly, it
can also be used to control the room temperature, depending on the property of LM35.
Experiment can be followed to evaluate whether this circuit can save energy through the use of
temperature sensor and thus promote efficiency.

6. TABLE OF CONTENTS
ACKNOWLEDGEMENT……………………………………………………………
ABSTRACT…………………………………………………………………………
TABLE OF CONTENT…………………………………………………………….
LIST OF FIGURES…………………………………………………………………..
LIST OF TABLES……………………………………………...……………………
1. INTRODUCTION…………………………………………………………….
a) GENERAL OVERVIEW………………………………………………....
b) BACKGROUND....................
c) PROJECT OBJECTIVES……………………………...…………………
2. LITERATUREL VIEW………………………………………………………
a) TECHNICAL UNITS…………………………………………………….
b) SYSTEM METHODOLOGY…………………………………………….
i. Block Diagram………………………………………………………….
ii. Circuit Diagram…………………………………………………………
iii. OPERATION……………………………………………………………..
c) HARDWARE COMPONETS………………………………………………………….
3. SCOPE AND APPLICATIONS…………………………………………….
4. PROJECT MANAGEMENT……………………………………………….
a) GANT CHART……………………………………………………..
b) COST ESTIMATION……………………………………………….
5. RESULT……………………………………………………………………..
6. SUMMARY…………………………………………………………………
BIBLIOGRAPHY
LIST OF FIGURES
Block diagram of Automatic temperature control dc fan……………………………..

7. Circuit diagram of Automatic temperature control dc fan…………………………….
Transformer…………………………………………………………………

8. LIST OF PICTURES
Schematic symbol of diode……………………………………………..
Capacitor………………………………………………………………..
BC 7806IC……………………………………………………………...
LED…………………………………………………………………….
Transistor……………………………………………………………….
Resistor……………………………………………………………………
Variable Resistor 5 KΩ………………………………………………
Matrics board…………………………………………………………..
Soldering Iron……….………………………………………………...
De-soldering Pump……………………………………………………

9. LIST OF TABLES
Gantt Chart………………………………………………………..
Cost Estimation…………………………………………………...

10. 1. Introduction:
Generaloverview
The circuit exploits the property of sensor to operate the DC Fan. A sensor is a type of
transducer. In a broader sense, a transducer is sometimes defined as any device that converts
energy from one form to another. Besides that, the component that made up the temperature
sensor is known as LM35. LM35 is a kind of temperature dependent resistor and its resistance
varies depending on the temperature in its vicinity.
b.background

12. Project objectives
This project is about to control the fan by heating the sensor, i.e. LM35, where the speed of the
fan is dependent and controlled by any device’s temperature like PC. As the temperature of the
device increases or decreases, the speed of fan increases or decreases respectively. So that this
device is termed as “Temperature Controlled Fan”.

13. 2. LITERATURE REVIEW
a. Technical Units
 Power Supply Unit
Power supply unit is that unit where power is supplied from the main power supply box
of the related home or industry.
 Rectification unit
Rectification unit is that unit where power is converted into the desired rate, quantity and
unit. Transformer, bridge rectifier, capacitor, and BC7806IC are the component of
Rectification Unit.
 Processing Unit
LM35, variable resistor, and transistor are processing unit. They take input from the
output of rectification unit and give output to the motor. Processing unit is sprit of the
Automatic Temperature Control DC Fan.
 Output Unit
Output Unit consist Motor. Motor works according to the processing unit output.

14. b.System methodology
i.Block diagram

15. Circuit diagram

16. iii.operation
The circuit is an open loop system. In this circuit initially 220V AC is stepped down to 12V AC.
Then this AC is converted into DC by a rectifier circuit consisting of 4 diodes D1, D2, D3 and
D4. One electrolytic capacitors C1 is connected parallel to give more sensitivity to the circuit as
they have the ability to smoothen the voltage across them. As the capacitor charges, the rate of
change of voltage slows, and charge slows, as the charging current falls thus showing an
exponential curve. An LED L1, through a resistance R1 is there across the capacitors to detect
the flow of current.
In this circuit LM35 is used which is also known as temperature sensor. The work of LM35 is to
sense the temperature and allow to pass the voltage across potentiometer. Potentiometer is here
to control the voltage across the motor. As we know LM35 gives output 10mV per degree
Celsius. When room temperature is high then LM35 allows high voltage to flow on
potentiometer. After that there is a pair of transistor (i.e. Darling ton pair) which is also known as
amplifier circuit. The Darlington transistor (often called a Darlington pair) is a constructed using
two bipolar transistors (either integrated or separated devices) connected in such a way that the
current amplified by the first transistor is amplified further by the second one. This configuration
gives a much higher current gain than each transistor taken separately. The current output from
the Darlington Pair has sufficient high gain to drive the motor. First current from LM35 and
further control by potentiometer is not enough to run the motor then Darlington pair provides
sufficient current to operate.
When LM35 senses low temperature then gradually speed of the motor also decreases. When the
motor starts, the LED L2 glows. It glows more brightly as the speed of the motor increases and
vice versa, and thus the increasing or decreasing speed can be identified.

17. Hardware Components
TRANSFORMER
Transformer is an electrical device that transfers electrical energy between two or
more circuits through electromagnetic induction .Commonly ,transformers are
used to increase or decrease the voltage of current in electric power applications
.It transformers power from one circuits to another without changing its frequency
but may be un different voltage level .
DIODE
In electronics, a diode is a two terminal electronic componentwith asymmetric
conductance, it has low (ideally zero) resistance to current in one direction, and
high (ideally infinite) resistance in the other. A semiconductordiode, the most
common type today, is a crystalline piece of semiconductormaterial with a p-n
junction connected to two electrical terminals .The most common function of a
diode is to allow an electric current to pass in one direction (called the diode’s
forward direction ),while blocking current in the opposite direction (the reverse
direction ). Thus , the diode can be viewed as an electronic version of a check
valve .This unidirectional behavior is called rectification ,and is used to convert

18. alternating current to direct current. Today, most diodes are made of silicon,, but
other semiconductors such as selenium or germanium are sometimes used.
fig: Diode
Picture shows the structure of diode.
Here, diodes are used to serve in rectification process.

19. CAPACITOR
Just like the resistor the Capacitor, sometimes referred to as a Condenser, is a
simple passive device that is used to “store electricity”. The capacitor is a
component which has the ability or “capacity” to store energy in the form of an
electrical charge producing a potential difference (Static Voltage) across its plates,
much like a small rechargeable battery.
There are many different kinds of capacitors available from very small capacitor
beads used in resonance circuits to large power factor correction capacitors, but
they all do the same thing, they store charge.
fig: Capacitor

20. VOLTAGE REGULATOR IC BC7806
BC7806 IC is a voltage regulator integrated circuit(IC) which is widely used in
electronic circuits. The 7806 is a 6 Volt voltage regulator IC with features such as
internal current limit, safe area protection, thermal protection Voltage regulator
circuit can be manually built using parts available in the market but it will take a
lot of time to assemble those parts on a PCB. Secondly, the costof those parts is
almost equal to the price of 7806 itself so professionals usually prefer to use 7806
IC instead of making a voltage regulator circuit from scratch. Before you start
using 7805, you will need to know about the pin structure of IC 7806. Apparently,
it looks like a transistor. It has three pins namely Vin, Common, and Vout.
LED
A light-emitting diode (LED) is a two-lead semiconductor light source. It is a p–n junction diode
that emits light when activated. When a suitable voltage is applied to the leads, electrons are able
to recombine with electron holes within the device, releasing energy in the form of photons.

21. TRANSISTOR
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. Today,
some transistors are packaged individually, but many more are found embedded in integrated
circuits.
In our project BC548 type transistor is used which serves as a switching device.
Pic: Transistor
Temperature sensor (LM 35):- The LM35 series are precision integrated-circuit
temperature sensor, whose output is linearly proportional to Celsius scale. The
LM35 does not require any external calibration or trimming to provide accuracies
of +-1/4 degree centigrade to +-3/4 centigrade over -55 to +150 degree centigrade

22. VARIABLE RESISTORS
Adjustable resistors
A resistor may have one or more fixed tapping points so that the resistance can be
changed by moving the connecting wires to different terminals. Some wirewound power resistors
have a tapping point that can slide along the resistance element, allowing a larger or smaller part
of the resistance to be used.
Where continuous adjustment of the resistance value during operation of equipment is
required, the sliding resistance tap can be connected to a knob accessible to an operator. Such a
device is called a rheostat and has two terminals.

23. Potentiometers
A potentiometer or pot is a three-terminal resistor with a continuously adjustable tapping
point controlled by rotation of a shaft or knob or by a linear slider. It is called a potentiometer
because it can be connected as an adjustable voltage divider to provide a variable potential at the
terminal connected to the tapping point. A volume control for an audio device is a common use
of a potentiometer.
Accurate, high-resolution panel-mounted potentiometers have resistance elements
typically wire wound on a helical mandrel, although some include a conductive-plastic resistance
coating over the wire to improve resolution. These typically offer ten turns of their shafts to
cover their full range. They are usually set with dials that include a simple turn’s counter and a
graduated dial. Electronic analog computers used them in quantity for setting coefficients, and
delayed-sweep oscilloscopes of recent decades included one on their panels.
Pic 2.7: Variable resistor 5K
MOTOR/FAN
A DC motor is any of a class of rotary electrical machines that converts direct current electrical
energy into mechanical energy. The most common types rely on the forces produced by
magnetic fields. Nearly all types of DC motors have some internal mechanism, either
electromechanical or electronic to periodically change the direction of current flow in part of the
motor.

24. MATRICS BOARD
A matrics board is a board printed circuit board that mechanically supports and
electrically connects electronic components using conductive tracks, pads and other features
etched from copper sheets laminated onto a non-conductive substrate. It is the basis where the
components are mounted for the final project.
Multi-layer PCBs allow for much higher component density. Conductors on different
layers are connected with plated-through holes called vias. Advanced PCBs may contain
components - capacitors, resistors or active devices - embedded in the substrate. The components
are mounted by using the various helpful components such solder wire paste and soldering iron.
Pic : Matrics Board
Printed circuit boards are used in all but the simplest electronic products. Alternatives to
PCBs include wire wrap and point-to-point construction. PCBs require the additional design
effort to lay out the circuit, but manufacturing and assembly can be automated. Manufacturing
circuits with PCBs is cheaper and faster than with other wiring methods as components are
mounted and wired with one single part. Furthermore, operator wiring errors Printed circuit
boards are used in all but the simplest electronic products. Alternatives to PCBs include wire
wrap and point-to-point construction. PCBs require the additional design effort to lay out the
electronics components.

25. SOLDERING IRON
A soldering iron is a hand tool used in soldering. It supplies heat to melt solder so that it
can flow into the joint between two work pieces.
A soldering iron is composed of a heated metal tip and an insulated handle. Heating is
often achieved electrically, by passing an electric current (supplied through an electrical cord or
battery cables) through a resistive heating element. Cordless irons can be heated by combustion
of gas stored in a small tank, often using a catalytic heater rather than a flame. Simple irons less
commonly used than in the past were simply a large copper bit on a handle, heated in a flame.
Pic : Soldering Iron
Soldering irons are most often used for installation, repairs, and limited production work
in electronics assembly. High-volume production lines use other soldering methods. Large irons
may be used for soldering joints in sheet metal objects. Less common uses include pyrography
(burning designs into wood) and plastic welding.
Soft solder is typically thought of when solder or soldering is mentioned, with a typical
melting range of 90 to 450 °C (190 to 840 °F).[3] It is commonly used in electronics, plumbing,
and assembly of sheet metal parts. Manual soldering uses a soldering iron or soldering gun.
Alloys that melt between 180 and 190 °C (360 and 370 °F) are the most commonly used.
Soldering performed using alloys with a melting point above 450 °C (840 °F) is called 'hard
soldering', 'silver soldering', or brass.
DE-SOLDERING PUMP AND PASTE
De-soldering Pump
A de-soldering pump, colloquially known as a solder sucker, is a manually-operated
device which is used to remove solder from a printed circuit board. There are two types: the

26. plunger style and bulb style. (An electrically-operated pump for this purpose would usually be
called a vacuum pump.)
Pic : De-soldering pump
The plunger type has a cylinder with a spring-loaded piston which is pushed down and
locks into place. When triggered by pressing a button, the piston springs up, creating suction that
sucks the solder off the soldered connection. The bulb type creates suction by squeezing and
releasing a rubber bulb. The pump is applied to a heated solder connection, and then operated to
suck the solder away.

27. 4.Project Managemen
a. Gantt chart:
2074-01 2074-01 2074-02 2074-02 2074-03
03-09 10-17 18-24 25-14 15-03 12-15
Object selection
Proposal submission
Proposal result
Final proposal submission
First presentation
Simulation
Integration
Components combine
Mid-term presentation

28. Incomplete component collection
Experiment &testing
Troubleshooting
Final presentation with output

29. b.CostEstimation
a.
SN Material Quantity Rate Amount Remarks
1 LM35 1 80 80
2 Motor 1 250 250
3 Transformer 1 150 150
4 Diodes 4 5 20
5 Voltage Regulator IC 1 50 50
6 Capacitor 1 35 35
7 Variable Resistor 1 40 40
8 LED 2 10 20
9 Fan 1 600 600
10 Transistor 2 25 50
11 Power cord 1 200 200
12 Glass As
required
500 500
13
Total

30. 5.Result
The circuit is very simple and easy to build. This paper elaborates the design and construction of
fan speed to control the temperature. Moreover, the fan speed will increase automatically if the
temperature will increase. As conclusion, the system which is designed in this work performs
very well for any temperature change and can be classified as automatic control.

31. 6.Summary
While attempting this project, various problems occurred. By encountering such
problems we prepare the project. We learnt many lessons from this project such as cost
management ,time management ,human resource management, material handling, concept of
operating automatic dc fan ,its scope and application. Beside this we are glad to complete

32. this project successfully. After reading this report, our juniors can gain knowledge about
project and its understanding and will help for their own project. At last, we would like to
thank our project guide Er.Bharat Nepal,HOD of electrical and electronic, all the teachers
and Korea Nepal Institute of Technology.
BIBLIOGRAPHY
www.google.com
www.wikipedia.orgwww
http://www.allaboutcircuits.com/
http://electronichub.com/
Zairi Ismael Rizman, Kim Ho Yeap, Nuraiza Ismail, Norizan Mohamad and Nur Hafizah
Rabi’ah Husin’s “Design an Automatic Temperature Control System for Smart Electric Fan

33. Using PIC”. International Journal of Science and Research (IJSR), India Online ISSN: 2319-
7064.
http://google.com/
Sushma Verma, Arpita Das, Subham Dey, Parijat Chowdhury; make a project on “Temperature
controlled fan”. Techno India College of Technology, Newtown, Mega City, Rajarhat, India.