BHOPAL
A MINOR PROJECT ON
“Temperature Controlled Fan”” Submitted in partial fulfillment of Bachelor’s Degree in Electronics & Communication Engineering Of RAJIV GANDHI PROUDYOGIKI VISHWAVIDYALAYA (University of Technology of Madhya Pradesh)
SUBMITTED BY: :-Prashant Samanway (0506ec091062) :- Shivam Vyas (0506ec091097) :-Shrikant Tripathi (0506ec091099) :-Veerendra Sengar (0506ec091109)
K C BANSAL COLLEGE OF TECHNOLOGY BHOPAL
(ELECTRONICS & COMMUNICATION)
CERTIFICATE This is to certify that project report entitled“Temperature Controlled Fan” presented by………………………………………………………….is the bonafide presentation of their work done by him under my supervision and guidance. They have submitted this project report towards partial fulfillment for the award of degree of bachelor of engineering of Rajiv Gandhi Proudyogiki Vishwavidhyalaya during the academic year 2012 .It is further certified that this work has been submitted elsewhere for the award of any degree.
Prof. PRAKASH SAXENA (HOD ) (EC Department)
(PROJECT INCHARGE) (EC Department)
ACKNOWLEDGEMENT
Presenting
the Project Report today remains an unparalleled event for us as it
recapitulates all our toils and efforts and thanks to every one who made it possible for us to achieve something which appeared like a Herculean Task.
Wherever and whatever we present today has been made possible by the undying efforts of project guides.
Last but not the least, we wish to thank all those noble hearts who directly or indirectly helped us to complete this project work.
-:Prashant samanway(0506ec091062) -: Shivam Vyas (0506ec091097) -:Veerendra sengar(0506ec09109) -:Shrikant tripathi (0506ec091099) EC VI Semester
Contents 1)
INTRODUCTION
2)
BLOCK DIAGRAM
3)
CIRCUIT DIAGRAM
4) 5)
WORKING PCB LAYOUT
6)
COMPONENT LIST WITH PRICE
7)
COMPONENT DESCRIPTION
8)
ADVANTAGE
9)
DISADVANTAGE
10)APPLICATIONS 11)FUTURE
ENCHANCEMENT
12)REFERENCES
13) DATASHEET
-: Introduction
With this simple circuit you will be able to control the speed of a DC fan according to temperature measured by a temp sensor. It’s an ideal add-on for your PC cooling fans to eliminate produced noise. Requested by some correspondents, this simple design allows an accurate speed control of 12V dc fan motors, proportional to temperature. A n.t.c. Thermistor (R1) is used as temperature sensor, driving two directly coupled complementary transistors wired in a dc feedback circuit. An optional circuitry was added to remotely monitor fan operation and to allow some sort of rough speed indication by means of the increasing brightness of a LED.
-: Circuit Diagram
.
Cost Analysis of Project
SR.NO
COMPONENTS USED
QUANTITY
COST (Rs.)
1
RESISTOR 1KΩ
1
2
2
Trimmer Cermet 470KΩ
1
2
3
Trimmer Cermet 22Ω
1
2
4
RESISTOR 680Ω
1
2
5
CAPACITOR 100µF,35V (Electrolytic)
1
3
6
DIODE
4
8
7
IC 7812 VOLTAGE REGULATOR
1
10
8
L.E.D. RED (3mm.dia)
1
2
9
TRANSFORMER 230V to 0-12V, 500mA
1
35
10
COPPER CLADED BOARD
1
30
11
FABRICATION COST
1
15
12
MISCELLANEOUS
1
24
13
BC547 45V 100mA NPN Transistor
1
5
14
BD140 80V 1.5A PNP Transistor
1
5
15
Fan Motor 12V 700mA max.
1
25
16
15K @ 20°C n.t.c. Thermistor
1
10
TOTAL
--
180
Component Description RESISTORS A resistor is a two-terminal electrical or electronic component that resists an electric current by producing a voltage drop between its terminals in accordance with Ohm's law.
The electrical resistance is equal to the voltage drop across the resistor divided by the current that is flowing through the resistor. Resistors are used as part of electrical networks and electronic circuits. Types
Fixed Resistors Some resistors are cylindrical, with the actual resistive material in the centre (composition resistors, now obsolete) or on the surface of the cylinder (film) resistors, and a conducting metal lead projecting along the axis of the cylinder at each end(axial lead). There are carbon film and metal film resistors. The photo above right shows a row of common resistors. Power resistors come in larger packages designed to dissipate heat efficiently. At high power levels, resistors tend to be wire wound types. Resistors used in computers and other devices are typically much smaller, often in surface-mount packages without wire leads. Resistors are built into integrated circuits as part of the fabrication process, using the semiconductor as the resistor. Most often the IC will use a transistor-transistor configuration or resistor-transistor configuration to obtain results. Resistors made with semiconductor material are more difficult to fabricate and take up too much valuable chip area.
Variable Resistors The variable resistor is a resistor whose value can be adjusted by turning a shaft or sliding a control. They are also called potentiometers or rheostats and allow the resistance of the device to be altered by hand. The term rheostat is usually reserved for higher-powered devices, above about ½ watt. Variable resistors can be inexpensive single-turn types or multi-turn types with a helical element. Some variable resistors can be fitted with a mechanical display to count the turns. Variable resistors can sometimes be unreliable, because the wire or metal can corrode or wear. Some modern variable resistors use plastic materials that do not corrode and have better wear characteristics.
Identification of Resistors The Standard EIA(Electronics Indusries Association) Color Code Table per EIA-RS-279 is as follows: Color
1st band 2nd band 3rd band (multiplier) 4th band (tolerance) Temp. Coefficient
Black 0
0
×100
Brown 1
1
×101
±1% (F)
100 ppm
Red
2
Orange 3
2
×102
3
3
15 ppm
4
25 ppm
±2% (G)
×10
Yellow 4
4
×10
Green 5
5
×105
±0.5% (D)
Blue
6
×106
±0.25% (C)
7
7
±0.1% (B)
8
±0.05% (A)
6
Violet 7 Gray
×10
8
8
×10
White 9
9
×109
Gold
×0.1
50 ppm
±5% (J)
Silver ×0.01 ±10% (K) Most axial resistors use a pattern of colored stripes to indicate resistance. SMT ones follow a numerical pattern. Cases are usually brown, blue, or green, though other colors are occasionally found like dark red or dark gray. One can use a multimeter to test the values of a resistor. Four-band axial resistors: Four-band identification is the most commonly used color coding scheme on all resistors. It consists of four colored bands that are painted around the body of the resistor. The scheme is simple: The first two numbers are the first two significant digits of the resistance value, the third is a multiplier, and the fourth is the tolerance of the value. Each color corresponds to a certain number, shown in the chart below. The tolerance for a 4-band resistor will be 2%, 5%, or 10%.
CAPACITOR
A capacitor is a device that stores energy in the electric field created between a pair of conductors on which equal magnitude but opposite sign electric charges have been placed. A capacitor is occasionally referred to using the older term condenser. SMD capacitors: electrolytic at the bottom line, ceramic above them; through-hole ceramic and electrolytic capacitors at the right side for comparison.Various types of capacitors are shown here.
Overview A capacitor consists of two electrodes, or plates, each of which stores an opposite charge. These two plates are conductive and are separated by an insulator or dielectric. The charge is stored at the surface of the plates, at the boundary
with the
dielectric. Because each plate stores
an equal
but opposite charge, the total charge
in the
capacitor is always zero. In the
diagram
below, the rotated molecules create
an
opposing electric field that partially
cancels
the field created by the plates, a
process
called dielectric polarization.
Capacitance in a capacitor When electric charge accumulates on the plates, an electric field is created in the region between the plates that is proportional to the amount of accumulated charge. This electric field creates a potential difference V = E·d between the plates of this simple parallel-plate capacitor.
The electrons within dielectric molecules are influenced by the electric field, causing the molecules to rotate slightly from their equillibrium positions. The air gap is shown for clarity; in a real capacitor, the dielectric is in direct contact with the plates. The capacitor's capacitance (C) is a measure of the amount of charge (Q) stored on each plate for a given potential difference or voltage (V) which appears between the plates:
In SI units, a capacitor has a capacitance of one farad when one coulomb of charge causes a potential difference of one volt across the plates. Since the farad is a very large unit, values of capacitors are usually expressed in microfarads (µF), nanofarads (nF) or picofarads (pF). The capacitance is proportional to the surface area of the conducting plate and inversely proportional to the distance between the plates. It is also proportional to the permittivity of the dielectric (that is, non-conducting) substance that separates the plates. The capacitance of a parallel-plate capacitor is given by:
where ε is the permittivity of the dielectric, A is the area of the plates and d is the spacing between them.
LIGHT-EMITTING DIODE
An LED is a special type of semiconductor .Like a normal diode, it consists of a chip of semiconducting material impregnated, or doped, with impurities to create a structure called a p-n junction . As in other diodes, current flows easily from the p-side, or anode to the n-side, or cathode , but not in the reverse direction. Charge-carriers - electrons and electron holes flow into the junction from electrodes with different voltages . When an electron meets a hole, it falls into a lower energy level , and releases energy in the form of a photon as it does so. The wavelength of the light emitted, and therefore its color, depends on the band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes recombine by a non-radiative transition which produces no optical emission, because these are
indirect bandgap materials. The materials used for an LED have a direct band gap with energies corresponding to near-infrared, visible or near-ultraviolet light. LED development began with infrared and red devices made with gallium arsenide . Advances in materials science have made possible the production of devices with ever shorter wavelengths , producing light in a variety of colors. Types Conventional LEDs are made from a variety of inorganic semiconductor materials, producing the following colors: •
Aluminum gallium arsenide (AlGaAs) - Red
•
Aluminum gallium phosphide (AlGaP) - Green
•
Aluminum gallium indium phosphide (AlGaInP) - High-Brightness Orange-Red, Orange, Yellow, and Green
•
Gallium arsenide phosphide (GaAsP) - Red, Orange-red, Orange and Yellow
•
Gallium phosphide (GaP) - Red, Yellow and Green
•
Gallium nitride (GaN) - Green, pure Green and Blue
•
Indium gallium nitride (InGaN) - Near Ultraviolet, Bluish-Green and Blue
•
Silicon carbide (SiC) as substrate - Blue
•
Silicon (Si) as substrate - Blue (under development)
•
Sapphire (Al2O3) as substrate - Blue
•
Zinc selenide (ZnSe) - Blue
•
Diamond (C) - Ultraviolet
The correct polarity of an LED can usually be determined as follows: Sign Polarity Terminal Wiring Pin out Interior Shape Marking
+ Positive Anode Red Long Small Round None
− Negative Cathode Black Short Large Flat Stripe
It should be noted that looking at the inside of the LED is not an accurate way of determining polarity. While in most LEDs the large part is the "+", in some it is the "-" terminal. The flat tabs or the short pins are more accurate ways of determining polarity.
TRANSISTOR
The transistor is a solid state semiconductor device that can be used for amplification , switching , voltage stabilization, signal modulation and many other functions. It allows a variable current, from an
external source, to flow between two of its terminals depending on the voltage or current applied to a third terminal. Transistors are made either as separate components or as part of an integrated circuit . Transistors are divided into two main categories: junction transistors (BJT) and field effect transistors (FETs ). Transistors have three terminals where, in simplified terms, the application of current (BJT) or voltage (FET) to the input terminal increases the
bipolar
conductivity between the other two terminals and hence controls current flow through those terminals. The physics of this "transistor action" are quite different for the BJT and FET; see the respective articles for further details. In analog circuits , transistors are used in amplifiers , (direct current amplifiers, audio amplifiers, radio frequency amplifiers), and linear regulated power supplies. Transistors are also used in digital circuits where they function as electrical switches. Digital circuits include logic gates, random access memory
(RAM ) and microprocessors .
Types Bipolar Junction Transistor The bipolar junction transistor (BJT) was the first type of transistor to be mass-produced. Bipolar transistors are so named because they conduct by using both majority and minority carriers. The three terminals are named emitter, base and collector. Two p-n junctions exist inside an NPN BJT: the base/collector junction and base/emitter junction. The PNP transistor similarly has two n-p junctions. The BJT is commonly described as a current-operated device because the emitter/collector current is controlled by the current flowing between base and emitter terminals. Unlike the FET, the BJT is a low input-impedance device. The BJT has a higher transconductance than the FET. Bipolar transistors can be made to conduct with light as well as current. Devices designed for this purpose are called phototransistors . Field-Effect Transistor The field-effect transistor (FET), sometimes called a unipolar transistor, uses either electrons or holes for conduction. The terminals of the FET are named source, gate and drain. A voltage applied between the gate and source controls the current flowing between the source and drain. In FETs the source/ drain current flows through a conducting channel near the gate. This channel connects the source terminal to the drain terminal. The channel conductivity is varied by the electric field generated by the voltage applied between the gate/source terminals. In this way the current flowing between the source and drain is controlled. FETs are divided into two families: junction FET (JFET ) and insulated gate FET (IGFET). The IGFET is more commonly known as metal oxide semiconductor FET (MOSFET). Unlike IGFETs, the JFET gate forms a diode with the channel which lies between the source and drain.
Functionally, this makes the N-channel JFET the solid state equivalent of the vacuum tube triode which, similarly, forms a diode between its grid and cathode. Also, both devices operate in the depletion mode, they both have a high input impedance, and they both conduct current under the control of an input voltage. MOSFETs are JFETs, in which the reverse biased pn junction is replaced by a semiconductor-metal Schottky junction. These, and the HEMFETs (high electron mobility FETs), in which a 2-dimensional electron gas with very high carrier mobility is used for charge transport, are especially suitable for use at very high frequencies (microwave frequencies; several GHz). FETs are further divided into depletion mode and enhancement mode types. Mode refers to the polarity of the gate voltage with respect to the source when the device is conducting. For Nchannel depletion mode FETs the gate is negative with respect to the source while for N-channel enhancement mode FETs the gate is positive. For both modes, if the gate voltage is made more positive the source/drain current will increase. For P-channel devices the polarities are reversed. Nearly all JFETs are depletion mode types and most IGFETs are enhancement mode types.
Other Transistor Types •
Unijunction transistors can be used as simple pulse generators. They comprise a main
body of either P-type or N-type semiconductor with ohmic contacts at each end (terminals Base1 and Base2). A junction with the opposite semiconductor type is formed at a point along the length of the body for the third terminal (Emitter). •
Dual gate FETs have a single channel with two gates in cascode; a configuration that is
optimized for high frequency amplifiers, mixers, and oscillators . •
Transistor arrays are used for general purpose applications, function generation and low-
level, low-noise amplifiers. They include two or more transistors on a common substrate to ensure close parameter matching and thermal tracking, characteristics that are especially important for long tailed pair amplifiers. •
Darlington transistors comprise a medium power BJT connected to a power BJT. This
provides a high current gain equal to the product of the current gains of the two transistors. Power diodes are often connected between certain terminals depending on specific use. •
Insulated gate bipolar transistors (IGBTs ) use a medium power IGFET, similarly
connected to a power BJT, to give a high input impedance. Power diodes are often connected between certain terminals depending on specific use. IGBTs are particularly suitable for heavyduty industrial applications. Single-electron transistors (SET) consist of a gate island between two tunnelling junctions. The tunnelling current is controlled by a voltage applied to the gate through a capacitor.
