This document presents a mini project on an automatic temperature controlled fan. It includes an introduction, block diagram, components used, power supply details, and an introduction to the microcontroller used - PIC16F72. The system uses an LM35 temperature sensor, PIC microcontroller, DC fan driver circuit, resistors, diodes, capacitors, and voltage regulator. It regulates fan speed automatically based on temperature readings from the LM35 sensor through PWM control of the fan's driver circuit.

1. MINI PROJECT PRESENTATION
AUTOMATIC TEMPERATURE
CONTROLLED FANStudent 1
Student 2
Student 3
Student 4
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2. Mini project by
Students of
College name, xxxxxx
your collge name:

3. INTRODUCTION
Ordinary fan regulators
Electronic fan regulators
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4. Why automatic temperature
controlledfan?
*Automatic speed control
*Low power loss
*Reduce Current Consumption
*Allows fan to ramp up or down smoothly to new speed
*Increase Fan Life
*A single temperature or all temperatures can control
the fan speed.
*Small size and economic
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5. Lm35
temperatur
e sensor
ADC
Microcontroller
(pic16f72/3
RPS
Driver
circuit
PWM
Increase in
temperature
BLOCK DIAGRAM
AC supply
230 V, 50Hz
12v dc fan
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6. Components Used
*LM35
*PIC Microcontroller
*DC FAN & Driver
circuit
*Resistors
* Diodes(bridge
rectifier)
*Capacitors
*Regulator
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7. POWER SUPPLY
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RPS ?

8. Introduction
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 Embedded system requires a regulated power supply. This power
supply circuit gives a variable regulated supply
 Through an arrangement of voltage regulator 7805 and
A regulated power supply is an embedded circuit; it converts
unregulated AC into a constant DC. With the help of a rectifier it
converts AC supply into DC. Its function is to supply a stable
voltage (or less often current), to a circuit or device that must be
operated within certain power supply limits. The output from the
regulated power supply may be alternating or unidirectional, but is
nearly always DC.

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REGULATED POWER SUPPLY

10. * A transformer is an electrical device
that transfers electrical energy
between two or more circuits
through electromagnetic induction.
Electromagnetic induction produces
an electromotive force within a
conductor which is exposed to time
varying magnetic fields. Transformers
are used to increase or decrease the
alternating voltages in electric power
applications..
your collge name:

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Step down
Transformer
 Its secondary voltage is less than its primary voltage.
 It is designed to reduce the voltage from the primary
winding to the secondary winding.
 The transformer converts high-voltage, low-current power
into low-voltage, high-current power.

12. WHAT IS A BRIDGE RECTIFIER?
 A bridge rectifier is an arrangement of four or
more diodes in a bridge circuit configuration
which provides the same output polarity for
either input polarity. It is used for converting an
alternating current (AC) input into a direct
current (DC) output. A bridge rectifier provides
full-wave rectification from a two-wire AC input,
therefore resulting in lower weight and cost when
compared to a rectifier with a 3-wire input from a
transformer with a center-tapped secondary
winding.
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13. TYPES OF BRIDGE RECTIFIERS
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 There are many different kinds of bridge rectifiers and at Future
Electronics we stock many of the most common types categorized by
maximum average rectified current, maximum reverse voltage,
maximum peak current, forward voltage, packaging type and
maximum reverse current. The parametric filters on our website can
help refine your search results depending on the required
specifications.
 The most common sizes for maximum average rectified current are
1A, 1.5 A, 4 A, 25 A and 35 A. We also carry bridge rectifiers with
maximum average rectified current as high as 1000 A. Forward
voltage can range from 450 mV to 1.1 kV, with the most common
bridge rectifier semiconductor chips having a forward voltage of 1.1 V
or 1 V.

14. APPLICATIONS FOR BRIDGE
RECTIFIERS
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The primary application of bridge rectifiers is to transform an AC
supply into DC power. All electronic devices require direct current, so
bridge rectifiers are used inside the power supplies of almost all
electronic equipment. Bridge rectifiers are also used for detecting the
amplitude of modulated radio signals. The signal may be amplified
before it is detected. If it is not, then a very low voltage drop diode or
a diode biased with a fixed voltage must be used. Rectifiers are also
used to supply polarized voltage for welding applications. Control of
the output current is required in such circuits, and this may be
achieved by replacing some of the diodes in a bridge rectifier with
thyristors, which are diodes whose voltage output can be regulated
by switching on and off with phase fired controllers.

15. FILTER
(CAPACITOR)
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capacitor is two metal plates separated by something that does not pass
electricity...[e.g: air].....So.....direct current [current flowing in only one
direction, as from an ordinary battery] cant pass through as the electrons
cant pass from one plate to another..But.. ac current[current constantly
reversing its direction, as in the electricity supplied to your home] can pass
through....this is because...since the current is constantly changing
direction....a plate will become positive...then negative ..then positive..and
so on...now although the electrons cant go through the air gap, the electric
field produced by the charged plate can....and this changing electric field
can alternatively pull and push electrons in the other plate...Thus, the ac
current can be transferred from one plate to another. So......capacitors block
dc but pass ac...and thus act as filters...

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 A filter is a capacitor which filters out a certain frequency or
range of frequencies from a circuit.
 Usually capacitors filter out very low frequency signals.
 These are signals that are very close to 0Hz in frequency
value.
 These are also referred to as DC signals.

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Voltage Regulator (LM
7805)
 A voltage regulator is designed to automatically maintain a fixed
voltage level.
 7805 is a voltage regulator integrated circuit.
 It is a member of 78xx series of fixed linear voltage regulator ICs.
 The xx in 78xx indicates the fixed output voltage it is designed to
provide.
 7805 provides +5V regulated power supply.

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INDICATOR
(LED)
 a thing that indicates the state or level of something.
 a device providing specific information on the state or
condition of something, in particular
 A light-emitting diode (LED) is a two-lead semiconductor
light source. It is a p–n junction diode, which 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.

19.  a sensor is an object whose purpose is
to detect events or changes in its
environment, and then provide a
corresponding output. A sensor is a type
oftransducer; sensors may provide
various types of output, but typically use
electrical or optical signals
your collge name:

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22. EMBEDDED SYSTEM
• An embedded system is a computer system with a dedicated function
within a larger mechanical or electrical system, often with real-time
computing constraints. It is embedded as part of a complete device often
including hardware and mechanical parts . Embedded systems control
many devices in common use today. Ninety-eight percent of
all microprocessors are manufactured as components of embedded
systems
OR
• we can say that it is “A combination of computer hardware and
software, and perhaps additional mechanical or other parts, designed
to perform a dedicated function. In some cases, embedded systems
are part of a larger system or product, as is the case of an antilock
braking system in a car ”.
College of Engineering XXXXXXXXXXX

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Significance
Due to their compact size, low cost and simple design
aspects made embedded systems very popular and encroached into
human lives and have become indispensable. They are found
everywhere from kitchen ware to space craft. To emphasize this
idea here are some illustrations.

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Embedded systems everywhere?
Embedded systems span all aspects of modern life and there are many
examples of their use.
a) Biomedical Instrumentation – ECG Recorder, Blood cell recorder,
patient monitor system
b) Communication systems – pagers, cellular phones, cable TV
terminals, fax and trans receivers, video games and so on.
c) Peripheral controllers of a computer – Keyboard controller, DRAM
controller, DMA controller, Printer controller, LAN controller, disk drive
controller.

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d) Industrial Instrumentation – Process controller, DC motor
controller, robotic systems, CNC machine controller, close loop engine
controller, industrial moisture recorder cum controller.
e) Scientific – digital storage system, CRT display controller,
spectrum analyser.

26. Why a microcontroller ?
A microcontroller is a single silicon chip with memory and all
Input/Output peripherals on it. Hence a microcontroller is also popularly
known as a single chip computer. Normally, a single microcomputer
has the following features :
 Arithmetic and logic unit
 Memory for storing program
 EEPROM for nonvolatile data storage
 RAM for storing variables and special function registers
 Input/output ports

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 Timers and counters
 Analog to digital converter
 Circuits for reset, power up, serial programming, debugging
 Instruction decoder and a timing and control unit
 Serial communication port

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What is inside an embedded system ?
Every embedded system consists of custom-built hardware
built around a Central Processing Unit (CPU). This hardware also
contains memory chips onto which the software is loaded. The
software residing on the memory chip is also called the ‘firmware’.
The operating system runs above the hardware, and the
application software runs above the operating system. The same
architecture is applicable to any computer including a desktop
computer. However, there are significant differences. It is not
compulsory to have an operating system in every embedded system.

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For small appliances such as remote control units, air-conditioners, toys
etc., there is no need fir an operating system and we can write only the software
specific to that application. For applications involving complex processing, it is
advisable to have an operating system.
In such a case, you need to integrate the application software with the
operating system and then transfer the entire software on to the memory chip.
Once the software is transferred to the memory chip, the software will continue to
run for a long time and you don’t need to reload new software .
The next slide shows the layered architecture of an embedded system.

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Layered architecture of an Embedded System

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Classification of Embedded Systems
Based on functionality and performance requirements,
embedded systems are classified as :
 Stand-alone Embedded Systems
 Real-time Embedded Systems
 Networked Information Appliances
 Mobile Devices

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Stand-alone Embedded Systems
As the name implies, stand-alone systems work in stand-alone mode.
They take inputs, process them and produce the desired output. The input
can be electrical signals from transducers or commands from a human
being such as the pressing of a button. The output can be electrical
signals to drive another system, an LED display or LCD display for
displaying of information to the users. Embedded systems used in process
control, automobiles, consumer electronic items etc. fall into this category.

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Real-time Systems
Embedded systems in which some specific work has to be done in a
specific time period are called real-time systems. For example,
consider a system that has to open a valve within 30 milliseconds
when the humidity crosses a particular threshold. If the valve is not
opened within 30 milliseconds, a catastrophe may occur. Such
systems with strict deadlines are called hard real-time systems.

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Languagesfor ProgrammingEmbeddedSystems
1. Assembly language was the pioneer for programming embedded
systems till recently. Nowadays there are many more languages to
program these systems. Some of the languages are C, C++, Ada,
Forth, and Java together with its new enhancement J2ME.
2. The presence of tools to model the software in UML, SDL is
sufficient to indicate the maturity of embedded software
programming
3. The majority of software for embedded systems is still done in C
language. Recent survey indicates that approximately 45% of the
embedded software is still being done in C language.
4. C++ is also increasing its presence in embedded systems. As C++ is
based on C language, thus providing programmer the object
oriented methodologies to reap the benefits of such an approach.

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1. C is very close to assembly programming and it allows very easy
access to underlying hardware. A huge number of high quality
compilers and debugging tools are available for the C language.
2. Though C++ is theoretically more efficient than C, but some of its
compilers have bugs due to the huge size of the language. These
compilers may cause a buggy execution.
3. C language can definitely claim to have more mature compilers
C++. Now in order to avail the extra benefits of C++ and plus to
avoid buggy execution, experts are doing efforts to identify a
subset of C++ that can be used in embedded systems and this
subset is called Embedded C++ .

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INTRODUCTION TO MICROCONTROLLER
PIC16F72 AND ACCESSOREIS
MICROCONTROLLER:
 A Microcontroller is a Microcomputer in a single Chip. That means that a
microcontroller chip includes a microprocessor (CPU) as well as some
often used peripherals. A controller is used to control some process or
aspect of the environment. A typical microcontroller application is the
monitoring a house. As the temperature rises, the controller causes the
windows to open If the temperature goes above a certain threshold, the
air conditioner is activated .
 As the process of miniaturization continued, all of the components
needed for a controller were built right onto one chip. A one chip
computer or microcontroller was born. A microcontroller is a highly
integrated chip, which includes, on one chip, all or most of the parts
needed for a controller. The microcontroller could be called a “one-chip-
solution”. It typically includes:

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 CPU (Central Processing Unit or the microprocessor)
 EEPROM / EPROM / PROM / ROM (Read Only Memory for the
program code)
 RAM (Random, Access Memory for the program code)
 I /O (Input / Output) devices (serial, parallel, ADC, DAC etc.)
 Timers
 Interrupt controller
 Embedded Controller
 ADC
 Calculator
 PWM function generator

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TYPES OF PROGRAMMABLE INTEGRATED CIRCUIT
(PIC)
 Base-line: 12-bit Instruction Word length
 Mid-Range: 14-bit Instruction Word
length
 High-End: 16-bit Instruction Word length
PIC MICROCONTROLLER ARCHITECTURE:
• Harvard architecture
• Long Word Instructions
• Single Word Instructions .Single Cycle Instructions
.Instruction Pipelining
• Reduced Instruction Set
• Register File Architecture
• Orthogonal (Symmetric) Instructions
The high performance of the PIC micro TM devices can be attributed to
a number of architectural features commonly found in RISC
microprocessors.

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 Only 35 single word instructions to learn
 All single cycle instructions except for program branches, which
are two-cycle
 Operating speed: DC - 20 MHz clock input DC - 200 ns
instruction cycle
 2K x 14 words of Program Memory, 128 x 8 bytes of Data
Memory (RAM)
 Pin out compatible to PIC16C72/72A and PIC16F872
 Interrupt capability
 Eight-level deep hardware stack
 Direct, Indirect and Relative Addressing modes
HIGH PERFOTMANCE RISC CPU

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PERIPHERAL FEATURES
High Sink/Source Current: 25 mA
Timer0: 8-bit timer/counter with 8-bit prescaler
Timer1: 16-bit timer/counter with prescaler, can be incremented during
SLEEP via external crystal/clock
Timer2: 8-bit timer/counter with 8-bit period register, prescaler and
postscaler
Capture, Compare, PWM (CCP) module
Capture is 16-bit, max. resolution is 12.5 ns
Compare is 16-bit, max. resolution is 200 ns
PWM max. resolution is 10-bit
8-bit, 5-channel analog-to-digital converter
Synchronous Serial Port (SSP) with SPI™ (Master/Slave) and I2C™
(Slave)
Brown-out detection circuitry for Brown-out Reset (BOR)

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CMOS TECHNOLOGY
Low power, high speed CMOS FLASH technology
Fully static design
Wide operating voltage range: 2.0V to 5.5V
Industrial temperature range
Low power consumption:
- < 0.6 mA typical @ 3V, 4 MHz
20 μA typical @ 3V, 32 kHz
< 1 μA typical standby current

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Features:
o 300RPM 12V DC motors with Gearbox
o 3000RPM base motor
o 6mm shaft diameter with internal hole
o 125gm weight
o Same size motor available in various rpm
o 0.35kgcm torque
o No-load current = 60 mA(Max), Load current = 300 mA(Max)
An electric motor is an electrical machine that converts
electrical energy into mechanical energy. The reverse of this would
be the conversion of mechanical energy into electrical energy and
is done by an electric generator.
DC MOTOR

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Working Principle Of A DC Motor
A motor is an electrical machine which converts electrical
energy into mechanical energy. The principle of working of a DC
motor is that "whenever a current carrying conductor is placed in a
magnetic field, it experiences a mechanical force". The direction of
this force is given by Fleming's left hand rule and it's magnitude is
given by F = BIL. Where, B = magnetic flux density, I = current and L
= length of the conductor within the magnetic field.

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Project schematic diagram

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Personal computers
Exhaust fans in large hotels
Washing machines
CD and DVD players
APPLICATION

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Advantagesand disadvantages
Advantages:
(1) Since it is an automated system ,it is programmed effectively so that
no interruptions would stop its functionality.
(2) To monitor the environment, that is not comfortable or possible to
monitor for humans(especially for extended periods of time Prevents
waste of energy.
Disadvantages-
(1) It can only be maintained by technical person .
(2) Due to temperature variation, after sometimes it’s efficiency may be
decreased.

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CONCLUSION AND
RESULT
 After designing, simulating, assembling, soldering and testing the circuit, we
came to the conclusion that our circuit of the temperature based fan speed
controller is working satisfactorily.
 The construction hardware perfect.
 The total project work perfectly and has negligible amount of unexpected
functioning.
 The problem statement is implemented.
 Hardware part is halfway implemented.
 Through simulations and after running the code in IDE abstract is verified
 As the technology is going on developing day by day, we prefer things to be
done automatically and in the same way our projects reduces the work to
mankind.