Download gas leakage alarm

“Transforming Live, Inventing Future”
A
Project Report
On
GAS LEAKAGE ALARM
By
1. Sakariya Mayank G. (106030311027)
2. Rathod Himanshu B. (106030311067)
3. Keyur Rughani G. (106030311002)
DEPARTMENT OF ELECTRONICS & COMMUNICATION
ENGINEERING
ATMIYA INSTITUTE OF TECHNOLOGY AND SCIENCE FOR
DIPLOMA STUDIES, RAJKOT- 360005.
[2012– 2013]
A
Project Report
On
GAS LEAKAGE ALARM
In partial fulfillment of requirements for the degree of
Diploma of Engineering
In
EC Engineering
Submitted By:
Under the Guidance of
1.Sakariya Mayank G.-106030311027
Mr. Jigar Ratnottar
2. Rathod Himanshu B.-106030311067
3. Rughani Keyur G.-106030311002
DEPARTMENT OF ELECTRONICS & COMMUNICATION
ENGINEERING
ATMIYA INSTITUTE OF TECHNOLOGY AND SCIENCE FOR
DIPLOMA STUDIES, RAJKOT- 360005.
[2012– 2013]
CERTIFICATE
This is to certify that the project entitled “GAS LEAKAGE ALARM” has been
carried out by the team under my guidance in partial fulfillment of the Diploma
of Engineering in Electronics & Communication in GTU during the academic
year 2012-2013 (Semester-5).
Team:
1. Sakariya Mayank G. (106030311027)
2. Rathod Himanshu B. (106030311067)
3. Keyur Rughani G. (106030311002)
Date:
Place: Rajkot
Guide
(Name of Guide)
Principal
Head, EC Department
External guide
ACKNOWLEDGEMENT
I greatly thank my faculty guide of the college Mr. Jigar Ratnottar. I m also
thankful to my external guide and chairperson of the industry I visited Mr.
Girdharbhai Patel. And Mr. Atulbhai Patel is a very genuine person and gave
me training giving time from his busy schedule. Lastly I heartily thank all my
friends and parents who guided and motivated me to complete my project
successfully.
Sakariya Mayank G.
Rathod Himanshu B.
Rughani Keyur G.
Contents
Abstract ................................................................................................................................................... I
List Of Figures......................................................................................................................................... II
List Of Tables ......................................................................................................................................... III
(1) Introduction ..................................................................................................................................... 1
1.1 Industry Visited ............................................................................................................................ 1
(2)
Problem definition .................................................................................................................. 3
2.1Detailed problem definition.......................................................................................................... 3
2.2 Problem in fire related security .............................................................................................. 4
(3) Feasibility ......................................................................................................................................... 5
3.1Financial feasibility: .............................................................................................................. 5
3.2 Resource feasibility: ................................................................................................................ 5
3.3 Technical feasibility .............................................................................................................. 5
(4) Hardware Description ...................................................................................................................... 7
4.1 Circuit Diagram............................................................................................................................. 7
4.2 List of components................................................................................................................... 7
4.3 Physical diagram .................................................................................................. 8
4.3.1 operation………………………………………….…………………………...8
(5) Component detail .......................................................................................................................... 10
(I) Resister ......................................................................................................................... 10
(II) Capacitor ...................................................................................................................... 13
(III) zener diode ................................................................................................................. 16
(IV) LED .............................................................................................................................. 20
(V)MQ-6 GAS SENSOR MODULE ....................................................................................... 24
(VI) IC 555 .......................................................................................................................... 25
(VII) Variable resister......................................................................................................... 26
(6) Project design ............................................................................................................................ 35
6.1 Software design .................................................................................................................... 35
6.2 Hardware design ............................................................................................................... 37
6.2.1 PCB designing steps………………………………………………………………………………….38
(7) Component Testing ................................................................................................................... 44
7.1 Resister Testing………………………………………………………………………………………………………………..44
7.2 Capacitor Testing…………………………………………………………………………………………….45
(8) Advantages and Application ..................................................................................................... 46
8.1 Advantages............................................................................................................................ 46
8.2 Application ........................................................................................................................ 46
(9) Data sheet.................................................................................................................................. 47
9.1 Zener diode ........................................................................................................................... 47
9.2 IC555 ................................................................................................................................. 48
9.3 SL100 TRANSISTOR.………………..………………………………………………………………….49
9.4 MQ-6 SENSOR………………………………………………………………..…………..……………50
(10) Daily schedule.......................................................................................................................... 52
Daily schedule…………………………………………………………………………………………………………………….52
References…………………………………………………………………………………………………………………………52
Conclusion……………………………………………………………………………………………………………..53
LIST OF FIGURES
Chapter
Topic NamePage Number
1.1
Bathtouch Industry
02
4.1
Gas leakage alarm
07
4.3
Physical diagram
08
5.1(a)
Resistor
11
5.1(b)
Resistor symbol
12
5.2(a)
Capacitor
13
5.2(b)
Parallel plate of capacitor
15
5.3(a)
symbol of zener & physical figure
16
5.3(b)
Construction of zener diode
16
5.3(c)
V-I characteristic
18
5.3(d)
Zener diode regulator
20
5.4(a)
symbol of LED
20
5.4(b)
figure of LED
23
5.4(c)
working of LED
24
5.4(d)
char. of LED
25
5.5
Physical diagram of gas sensor module
26
5.6(a)
Pin diagram of IC 555
27
5.7(a)
Symbol of variable resistor
29
5.7(b)
variable resistor
29
5.7(c)
char. graph of variable resistor
31
5.7(d)
Coted potentiometer
32
6.1
PCB layout
40
LIST OF TABLES
Chapter
Topic NamePage Number
4.2
list of component table
7
5.1(c)
Resistor color coding table
12
5.6(b)
Pin description of IC 555
28
9.1
maximum rating of zener diode
48
9.2
maximum rating of IC555
49
9.3
maximum rating of SL100 transistor
50
10.1
Daily schedule
52
ABSTRACT
LPG gas is supplied in pressurized steel cylinders. As this gas is heavier
than air, when it leaks from a cylinder it flows along floor and tends to settle in
low spots such as a basement. This can cause fire or suffocation if not dealt
with. Here is a circuit that detects the leakage of LPG gas and alerts the user
through audio-visual indications.
This LPG Gas Sensor (MQ6), ideal sensor for use to detect the presence
of a dangerous Liquefied petroleum gas (LPG) and it has high sensitivity to
propane, butane, isobutene, natural gas. The sensor can also be used to detect
combustible gases, especially methane. This circuit can detect leakages in your
Home, car or in a service station, storage tank environment. This unit can be
easily implemented to industrial level by upgrading its ranges.
This project is designed to detect the LPG from 200parts per million
(PPM) to 10,000 PPM. Whenever there is LPG concentration of 1000 ppm
(parts per million) in the area, the OUT pin of the sensor module goes high.
This signal drives timer IC 555, which is wired as an astable multivibrator. The
multivibrator basically works as a tone generator. A buzzer is connected to
produce audible alert signal.
Chapter-1
Introduction
1. Introduction:
The project we have done is entailed IC555, gas sensor module and
variable register with electronics application. This is an industrial defined
project i.e. IDP. And the title is so given from the problem definition related
to“fast way to detect gas Leakage with compare to conventional way of gas
detection”. Wegot the above mentioned problem definition from our industrial
visit to Bathtouch industry.
1.1
Industry visited:
Bathtouch Metals Pvt Ltd.
Plot no G-1611, F Road,
Metoda G.I.D.C
Kalawad Road
Rajkot - 360035, Gujarat
India
www.bathtouchmetal.com
For the industrial defined project I visited bathtouch Industry Works
(Metoda). The industry is located in Metoda. The best part of this industry is the
beautiful environment and friendly atmosphere. The people working in this
industry are very genuine and down to earth. They co-operated on my visit to
this industry.And helped in every possible manner.
1.1 Bathtouch Industry
Bathtouch industry was founded in 1955 by Mr.Girdharbhai. The
company adopted advanced gear technology. Step by step gear shaping,
hobblingand shaving and finally added gear grinds technology also. The
company started manufacturing 2-3 type electronic component a day and today
it is making 75-80types component daily on the automatic machine. In last 4
years Mr. Ravi Vaghela, grandson of Mr. Bharat Vaghela has become an added
part of the company
Chapter 2
Problem definition
2.1 Detailed problem definition:
To understand the problem definition deeply we first need to know about
the welding machine and the problem occurred in the machine.
2.1.1 Welding machine:It is necessary to know about the machine in which we are making our
project. Thus I have included the detailed description of the welding machine in
which I m going to place my project.
What is welding?
Welding stands for joining the different metal parts which is done by
welding machine. And the welding machine uses the LPG type of the gases.
While people in most walks of life have heard of this term, welding
process has touched almost every form of manufacturing process in one way or
another. If you'll be working in manufacturing, it's likely that you'll be dealing
with welding small or large machine on a regular basis.
While there are exceptions to this statement, welding machines typically
replace (or work in conjunction with) some existing manufacturing processes.
Take one of the simplest manufacturing processes;joint the plate of metal, for
example.
2.2 Problem in fire related security:
While visiting Bathtouch industry we saw that emergency fire security in
other way but in that way we observed that it is difficult to
determineincidentally gas leakage of gas is done or not.
And if it is not done than so much time will be waste for knowing this
and we also show manytimethe risky condition that may occurs and no one can
know about it.
Chapter 3
Feasibility
3.1Financial feasibility:
The resources used in this project are quite feasible financially.
Components list:
 Resisters
 Zenerdiode
 capacitor
 555 IC
 MQ-6
 Variable resister
The list of components given above shows that all the components are
cheap and feasible. The company will not have any problem in using this simple
project circuit.
3.2 Resource feasibility:
All the resources used in this project are easily available.
The IC555 used in this project might be difficult to find in the market.
But it is easily available from the dual supply.
3.3 Technical feasibility:
After we gave our idea to the industry labor, then the industry person
told that our idea was quite feasible technically and promised to try it on their
Machines.
Thus the project is feasible technically but cannot be used on machines
directly because it needs some specifications and data of the machine to make
the project fit for machine.
But the industry I visited didn’t share the data of the machines and kept
them personal. They had some terms and conditions according to which I had
to work. And they didn’t give any detailed specifications of the machines and
they even didn’t allow working on their machines.
Chapter 4
Circuit Description
4.1 Circuit Diagram:
4.1 Fig. of GAS LEAKAGE ALARM
4.2 List of components:
SR NO.
Name of component
Range/Type
Quantity
1
Transistor
SL100
1
2
IC-555
4.5 to 15 V(Vcc)
1
3
Capacitor
0.1uf
1
4
Resister
10kΩ, 4.7kΩ,1kΩ
6
22 Ω ,560Ω
5
LED
1V
1
6
MQ-6
1000ppm
1
7
Variable Resister
10K Ω
1
8
Zener Diode
5V
1
4.2.List of components of above circuit
4.3
Physical diagram:
4.3 Fig of physical circuit diagram
4.3.1
Operation:
Pin details of the gas sensor module are shown in Fig. 2. An MQ-6 gas
sensor is used in the gas sensor module. As per its datasheet, it has high
sensitivity to propane, butane, isobutene,
LPG and natural gas. The sensor can also be used to detect combustible
gases, especially methane. This circuit has been tested with LPG gas and was
found to work very fine.
Whenever there is LPG con-centration of 1000 ppm (parts per million) in
the area, the OUT pin of the sensor module goes high. This signal drives timer
IC 555, which is wired as an astablemultivibrator. The multivibrator basically
works as a tone generator. Output pin 3 of IC 555 is connected to LED1 and
speaker-driver transistor SL100 through current-limiting resis-tors R5 and R4,
respectively. LED1 glows and the alarm sound to alert the user of gas leakage.
The pitch of the tone can be changed by varying preset VR1. Use a suitable
heat-sink for transistor SL100.
Chapter 5
Components detail
Component details:
5.1 Resistor:
Register is a passive element. These components are split into two
categories; those which dissipate energy and those which store it. The property
of a substance, which opposes the flow of an electrical current through it, is
called the “resistance” (measured in ohms). Fixed resisters are used in circuit
diagram.
A linear resistor is a linear, passive two-terminal electrical component
that implements electrical resistance as a circuit element. The current through a
resistor is in direct proportion to the voltage across the resistor's terminals.
Thus, the ratio of the voltage applied across a resistor's terminals to the intensity
of current through the circuit is called resistance. This relation is represented by
Ohm's law:
Resistors are common elements of electrical networks and electronic
circuits and are ubiquitous in most electronic equipment. Practical resistors can
be made of various compounds and films, as well as resistance wire (wire made
of a high-resistivity alloy, such as nickel-chrome). Resistors are also
implemented within integrated circuits, particularly analog devices, and can also
be integrated into hybrid and printed circuits.
The electrical functionality of a resistor is specified by its resistance:
common commercial resistors are manufactured over a range of more than nine
orders of magnitude. When specifying that resistance in an electronic design,
the required precision of the resistance may require attention to the
manufacturing tolerance of the chosen resistor, according to its specific
application.
The temperature coefficient of the resistance may also be of concern in
some precision applications. Practical resistors are also specified as having a
maximum power rating which must exceed the anticipated power dissipation of
that resistor in a particular circuit: this is mainly of concern in power electronics
applications. Resistors with higher power ratings are physically larger and may
require heat sinks. In a high-voltage circuit, attention must sometimes be paid to
the rated maximum working voltage of the resistor.
Practical resistors have a series inductance and a small parallel
capacitance; these specifications can be important in high-frequency
applications. In a low-noise amplifier or pre-amp, the noise characteristics of a
resistor may be an issue. The unwanted inductance, excess noise, and
temperature coefficient are mainly dependent on the technology used in
manufacturing the resistor. They are not normally specified individually for a
particular family of resistors manufactured using a particular technology.
A family of discrete resistors is also
characterized according to its form factor,
that is, the size of the device and the position
of its leads (or terminals) which is relevant in
the practical manufacturing of circuits using
them.
Fig.5.1 (a)of resistors
The symbol for a resistor is shown in the below.
Fig. 5.1(b): Resistor symbols
The unit for measuring resistance is the OHM. (The Greek letter Ω called Omega). Higher resistance values are represented by "k" (kilo-ohms) and
M (Meg ohms).
5.1.1 Resistor Markings:Resistance value is marked on the resistor body. Most resistors have 4
bands. The first two bands provide the numbers for the resistance and the third
band provides the number of zeros. The fourth band indicates the tolerance.
Tolerance values of 5%, 2%, and 1% are most commonly available.
The following table shows the colors used to identify resistor values:
Fig. 5.1(c): Four-band resistor, c. Five-band resistor, d. Cylindrical SMD
resistor, e. Flat SMD resistor
5.2 Capacitor:
Fig5.2(a) Capacitor
A capacitor (formerly known as condenser) is a passive two-terminal
electrical component used to store energy in an electric field. The forms of
practical capacitors vary widely, but all contain at least two electrical
conductors separated by a dielectric (insulator); for example, one common
construction consists of metal foils separated by a thin layer of insulating film.
Capacitors are widely used as parts of electrical circuits in many common
electrical devices.
When there is a potential difference (voltage) across the conductors, a
static electric field develops across the dielectric, causing positive charge to
collect on one plate and negative charge on the other plate. Energy is stored in
the electrostatic field. An ideal capacitor is characterized by a single constant
value, capacitance, measured in farads. This is the ratio of the electric charge on
each conductor to the potential difference between them.
The capacitance is greatest when there is a narrow separation between
large areas of conductor; hence capacitor conductors are often called "plates,"
referring to an early means of construction. In practice, the dielectric between
the plates passes a small amount of leakage current and also has an electric field
strength limit, resulting in a breakdown voltage, while the conductors and leads
introduce an undesired inductance and resistance.Capacitors are widely used in
electronic circuits for blocking direct current while allowing alternating current
to pass, in filter networks, for smoothing the output of power supplies, in the
resonant circuits that tune radios to particular frequencies and for many other
purposes.
The simplest capacitor consists of two parallel conductive plates
separated by a dielectric with permittivity ε (such as air). The model may also
be used to make qualitative predictions for other device geometries. The plates
are considered to extend uniformly over an area A and a charge density ±ρ =
±Q/A exists on their surface. Assuming that the width of the plates is much
greater than their separation d, the electric field near the centre of the device
will be uniform with the magnitude E = ρ/ε. The voltage is defined as the line
integral of the electric field between the plates.Solving this for C = Q/V reveals
that capacitance increases with area and decreases with separation
…………………………..(1)
The capacitance is therefore greatest in devices made from materials with
a high permittivity, large plate area, and small distance between plates.
We see that the maximum energy is a function of dielectric volume,
permittivity, and dielectric strength per distance. So increasing the plate area
while decreasing the separation between the plates while maintaining the same
volume has no change on the amount of energy the capacitor can store. Care
must be taken when increasing the plate separation so that the above assumption
of the distance between plates being much smaller than the area of the plates is
still valid for these equations to be accurate.
Fig 5.2(b) parallel plates of capacitor
5.3 Zenger Diode:
Zener diodes are a form of semiconductor diode that is widely used in
electronics circuits as voltage references. Zener diodes provide a stable and
defined voltage and as a result Zener diode circuits are often used in power
supplies when regulated outputs are needed. Zener diodes are cheap and they
are also easy to use and as a result they are used in many applications and many
circuits.
5.3(a)Symbol&Physical figure
5.3.1 zenerDiode Construction:
The zener diode's operation depends on the heavy doping of its p-n junction.
The depletion region formed in the diode is very thin (<0.000001 m) and the
electric field is consequently very high (about 500000 V/m) even for a small
reverse bias voltage of about 5 V, allowing electrons to tunnel from the valence
band of the p-type material to the conduction band of the n-type material.
In the atomic scale, this tunneling corresponds to the transport of valence band
electrons into the empty conduction band states; as a result of the reduced
barrier between these bands and high electric fields that are induced due to the
relatively high levels of doping on both sides. The breakdown voltage can be
controlled quite accurately in the doping process. While tolerances within
0.05% are available, the most widely used tolerances are 5% and 10%.
Breakdown voltage for commonly available zener diodes can vary widely from
1.2 volts to 200 volts.
Surface Zeners
The emitter-base junction of a bipolar NPN transistor behaves as a zener diode,
with breakdown voltage at about 6.8 V for common bipolar processes and about
10 V for lightly doped base regions in BiCMOS processes. Older processes with
poor control of doping characteristics had the variation of Zener voltage up to
+-1 V, newer processes using ion implantation can achieve no more than +0.25 V. The NPN transistor structure can be employed as a surface zener diode,
with collector and emitter connected together as its cathode and base region as
anode. In this approach the base doping profile usually narrows towards the
surface, creating a region with intensified electric field where the avalanche
breakdown occurs. The hot carriers produced by acceleration in the intense field
sometime shoot into the oxide layer above the junction and become trapped
there. The accumulation of trapped charges can then cause Zener walkout, a
corresponding change of the Zener voltage of the junction. The same effect can
be achieved by radiation damage.
The emitter-basedzener diodes can handle only smaller currents as the
energy is dissipated in the base depletion region which is very small. Higher
amount of dissipated energy (higher current for longer time, or a short very high
current spike) will cause thermal damage to the junction and/or its contacts.
Partial damage of the junction can shift its Zener voltage. Total destruction of
the Zener junction by overheating it and causing migration of metallization
across the junction ("spiking") can be used intentionally as a Zener
zap antifuse.
Subsurface Zeners
A subsurface Zener diode, also called buried Zener, is a device similar to the
surface Zener, but with the avalanche region located deeper in the structure,
typically several micrometers below the oxide. The hot carriers then lose energy
by collisions with the semiconductor lattice before reaching the oxide layer and
cannot be trapped there. The Zener walkout phenomenon therefore does not
occur here, and the buried Zeners have voltage constant over their entire
lifetime. Most buried Zeners have breakdown voltage of 5-7 volts. Several
different junction structures are used.
5.3.2 Diode Biased Voltage
Zener Diode I-V Characteristics
5.3(C)V-I characteristic
The Zener Diode is used in its "reverse bias" or reverse breakdown
mode, i.e. the diodes anode connects to the negative supply. From the I-V
characteristics curve above, we can see that the zener diode has a region in its
reverse bias characteristics of almost a constant negative voltage regardless of
the value of the current flowing through the diode and remains nearly constant
even with large changes in current as long as the zener diodes current remains
between the breakdown current IZ(min) and the maximum current rating IZ(max).
This ability to control itself can be used to great effect to regulate or
stabilize a voltage source against supply or load variations. The fact that the
voltage across the diode in the breakdown region is almost constant turns out to
be an important application of the zener diode as a voltage regulator. The
function of a regulator is to provide a constant output voltage to a load
connected in parallel with it in spite of the ripples in the supply voltage or the
variation in the load current and the zener diode will continue to regulate the
voltage until the diodes current falls below the minimum IZ(min) value in the
reverse breakdown region.
The Zener Diode Regulator
Zener Diodes can be used to produce a stabilized voltage output with low
ripple under varying load current conditions. By passing a small current through
the diode from a voltage source, via a suitable current limiting resistor (RS), the
zener diode will conduct sufficient current to maintain a voltage drop of out. We
remember from the previous tutorials that the DC output voltage from the half
or full-wave rectifiers contains ripple superimposed onto the DC voltage and
that as the load value changes so too does the average output voltage. By
connecting a simple zenerstabiliser circuit as shown below across the output of
the rectifier, a more stable output voltage can be produced.
Zener Diode Regulator
The resistor, RS is connected in series with the zener diode to limit the current
flow through the diode with the voltage source, VS being connected across the
combination. The stabilized output voltage Voutis taken from across the zener
diode. The zener diode is connected with its cathode terminal connected to the
positive rail of the DC supply so it is reverse biased and will be operating in its
breakdown condition. Resistor RS is selected so to limit the maximum current
flowing in the circuit.
With no load connected to the circuit, the load current will be zero, (IL = 0), and
all the circuit current passes through the zener diode which in turn dissipates its
maximum power. Also a small value of the series resistor RS will result in a
greater diode current when the load resistance RL is connected and large as this
will increase the power dissipation requirement of the diode so care must be
taken when selecting the appropriate value of series resistance so that the zeners
maximum power rating is not exceeded under this no-load or high-impedance
condition.
The load is connected in parallel with the zener diode, so the voltage
across RL is always the same as the zener voltage, (VR = VZ). There is a
minimum zener current for which the stabilization of the voltage is effective and
the zener current must stay above this value operating under load within its
breakdown region at all times. The upper limit of current is of course dependent
upon the power rating of the device. The supply voltage VS must be greater
than VZ.
One small problem with zener diode stabilizer circuits is that the diode can
sometimes generate electrical noise on top of the DC supply as it tries to
stabilize the voltage. Normally this is not a problem for most applications but
the addition of a large value decoupling capacitor across the zeners output may
be required to give additional smoothing.
Then to summarize a little. A zener diode is always operated in its reverse
biased condition. A voltage regulator circuit can be designed using a zener
diode to maintain a constant DC output voltage across the load in spite of
variations in the input voltage or changes in the load current. The zener voltage
regulator consists of a current limiting resistor RS connected in series with the
input voltage VS with the zener diode connected in parallel with the load RL in
this reverse biased condition. The stabilized output voltage is always selected to
be the same as the breakdown voltage VZ of the diode.
5.4 LED:
A light-emitting diode (LED) is a semiconductor light source. LEDs are
used as indicator lamps in many devices and are increasingly used for other
lighting. Introduced as a practical electronic component in 1962, early LEDs
emitted low-intensity red light, but modern versions are available across the
visible, ultraviolet, and infrared wavelengths, with very high brightness.
When a light-emitting diode is forward-biased (switched on), electrons
are able to recombine with electron holes within the device, releasing energy in
the form of photons. This effect is called electroluminescence and the color of
the light (corresponding to the energy of the photon) is determined by the
energy gap of the semiconductor. LEDs are often small in area (less than
1 mm2), and integrated optical components may be used to shape its radiation
pattern.
Fig 5.4(a)Diagram of LED
LEDs present many advantages over incandescent light sources including
lower energy consumption, longer lifetime, improved robustness, smaller size,
and faster switching. LEDs powerful enough for room lighting are
relativelyexpensive and require more precise current and heat management than
compact fluorescent lamp sources of comparable output.
Light-emitting diodes are used in applications as diverse as replacements
for aviation lighting, automotive lighting (in particular brake lamps, turn
signals, and indicators) as well as in traffic signals. LEDs have allowed new
text, video displays, and sensors to be developed, while their high switching
rates are also useful in advanced communications technology.
Infrared LEDs are also used in the remote control units of many
commercial products including televisions, DVD players, and other domestic
appliances.
Practical use:
The first commercial LEDs were commonly used as replacements for
incandescent and neon indicator lamps, and in seven-segment displays, first in
expensive equipment such as laboratory and electronics test equipment, then
later in such appliances as TVs, radios, telephones, calculators, and even
watches (see list of signal uses).
These red LEDs were bright enough only for use as indicators, as the
light output was not enough to illuminate an area. Readouts in calculators were
so small that plastic lenses were built over each digit to make them legible.
Later, other colors grew widely available and also appeared in appliances and
equipment. As LED materials technology grew more advanced, light output
rose, while maintaining efficiency and reliability at acceptable levels.
The invention and development of the high-power white-light LED to use
for illumination, which is fast replacing incandescent and fluorescent lighting.
(See list of illumination applications).
Most LEDs were made in the
very common 5 mm T1¾ and 3 mm
T1 packages, but with rising power
output, it has grown increasingly
necessary to shed excess heat to maintain
5.4(b) LED
Reliability, so more complex packages have been adapted for efficient
heat dissipation. Packages for state-of-the-art high-power LEDs bear little
resemblance to early LEDs.
Fig.5.4 (b) LED
Working of LED
The LED consists of a chip of semiconducting material doped with
impurities to create 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 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.
Fig.5.4(c)Inner workings of LED
The wavelength of the light emitted, and thus 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-radioactive
transition, which produces no optical emission, because these are indirect band
gap materials. The materials used for the LED have a direct band gap with
energies corresponding to near-infrared, visible, or near-ultraviolet light.
Fig 5.4(d)I-V diagram for a diode. An LED will begin to emit light when the
on-voltage is exceeded. Typical on voltages are 2–3 volts.
LED development began with infrared and red devices made with gallium
arsenide. Advances in materials science have enabled making devices with
ever-shorter wavelengths, emitting light in a variety of colors.
LEDs are usually built on an n-type substrate, with an electrode attached
to the p-type layer deposited on its surface. P-type substrates, while less
common, occur as well. Many commercial LEDs, especially GaN/InGaN, also
use sapphire substrate.
Most materials used for LED production have very high refractive
indices. This means that much light will be reflected back into the material at
the material/air surface interface. Thus, light extraction in LEDs is an important
aspect of LED production, subject to much research and development.
5.5 MQ-6 GAS SENSOR MODULE:
Description:
This LPG Gas Sensor Module is latest revision V2, which replaces the
old module Part No: SEN-1327 .It is designed to enable LPG detection interface
to Microcontroller without ADC Channels and programming. Apart from the
trigger level setting Pot an extra Pot is also added in new version, which
5.5 Physical diagram of GAS sensor module
Allowssetting the sensitivity of the sensor. It allows to determine when a
preset LPG gas level has been reached or exceeded. Interfacing with the sensor
module is done through a 4-pin breadboard compatible SIP header and
requires One I/O pin from the host microcontroller.
The onboard microcontroller provide initial heating interval after power
up and then starts to measure LPG sensor output. If it found the
LPG concentration above settled value , it will inform the Host controller by
pulling the Output Pin to High and Starts to blink a onboard status LED.
The sensor module is mainly intended to provide a means of comparing LPG
sources and being able to set an alarm limit when the source becomes excessive.
Features:
 Uses the MQ-6 LPG Gas Sensor
 Compatible with most microcontrollers
 Analog Sensor voltage is available at ANG pin.
 Onboard Status and Power LED
 Onboard Pot for threshold setting
 Onboard Pot for Sensitivity setting
5.6IC 555:
The555 monolithic timing circuit is a highly stable controller capable of
producing accurate time delays or oscillation.
n the time delay mode of operation, the time is precisely controlled by
one external resistor and capacitor. For astable operations an oscillator, the free
running frequency and the duty cycle are both accurately controlled with two
external resistors and one capacitor.
The circuit may be triggered and reset on falling waveforms, and the
output structure can source or sink up to 200mA. The NE555 is available in
plastic and ceramic mini dip package and in a 8-leadmicropackage and in metal
Pin Diagram:
5.6(a) pin diagram of IC555
Pin Description:
Pin Name
Purpose
1
GND
Ground, low level (0 V)
2
TRIG
OUT rises, and interval starts, when this input falls below 1/3 VCC.
3
OUT
This output is driven to approximately 1.7V below +VCC or GND.
A timing interval may be reset by driving this input to GND, but the
4
RESET timing does not begin again until RESET rises above approximately
0.7 volts. Overrides TRIG which overrides THR.
5
CTRL
"Control" access to the internal voltage divider (by default, 2/3 VCC).
6
THR
The interval ends when the voltage at THR is greater than at CTRL.
7
DIS
8
V+,VCC Positive supply voltage is usually between 3 and 15 V.
Open collector output; may discharge a capacitor between intervals. In
phase with output.
5.6(b) pin description of IC555
5.7 Variable Resistors:
These are resistors whose resistance can be altered and they have three
connections. There are two connections at either end of the resistance material,
which is commonly known as the track. The third connection is made to a
conducting slider, commonly known as the wiper, which is in contact with the
track and can be slid along it from one end to the other. The current or voltage
available at the wiper is then related to the position that it has along the track.
Symbol:
Fig 5.7(a) symbol of variable Resistor
Variable Resistors can be used in a circuit to alter resistance and in this
situation only two connections are used. One end and the wiper. It is good
practice to connect the free end to the wiper so in the event that the wiper fails
to connect, the variable resistor will go to maximum resistance protecting the
circuit.
Potentiometer or Pot is the name given when the variable resistor is used
as a Potential Divider to alter voltage in part of the circuit from 9 to 0 volts or
as a speaker balance control. All three connections are used.
Turn the Potentiometer shaft clockwise and anti-clockwise and see how
the voltages change from 0 to 9 volts.
Fig.5.7 (b) Variable Resistors
There are two types of variable resistors:
1. Preset:The resistance of part of the circuit needs to be adjusted once during
manufacture to allow for component variations. Presets are soldered directly
onto the Printed Circuit Board. (PCB)
Fig(a) Pre Set
2. Control:The resistance of part of the circuit is altered frequently such as volume
control. These are available as single gang, double gang (stereo volume) and
single gang switched. They are available as either rotary shaft or slider.

Fig(b)Rotary Control

Fig(c) Slide Control
Values of Variable Resistors:Typical values:- 100R 220R 470R 1K 2K2 4K7 10K 22K 47K
100K
220K
470K
Resistance is available in two forms:- Linear and Log values.
1M
Linear values change directly with the amount of movement giving a
straight line on the graph. Log values start off with a small change in resistance
for a large movement and gradually alters to a large change in resistance for a
small amount of movement. Curved line on the graph.
Fig 5.7(c)Graph of Linear and Log Resistance values against Rotation
5.7.1 Potentiometers:
Potentiometers (also called pots) are variable resistors, used as voltage or
current regulators in electronic circuits. By means of construction, they can be
divided into 2 groups: coated and wire-wound.
With coated potentiometers, (figure 1.6a), insulator body is coated with a
resistive material. There is a conductive slider moving across the resistive layer,
increasing the resistance between slider and one end of pot, while decreasing
the resistance between slider and the other end of pot.
Fig 5.7(d): Coated potentiometer
Wire-wound potentiometers are made of conductor wire coiled around
insulator body. There is a slider moving across the wire, increasing the
resistance between slider and one end of pot, while decreasing the resistance
between slider and the other end of pot.
Coated pots are much more common. With these, resistance can be linear,
logarithmic, inverse-logarithmic or other, depending upon the angle or position
of the slider. Most common are linear and logarithmic potentiometers, and the
most common applications are radio-receivers, audio amplifiers, and similar
devices where pots are used for adjusting the volume, tone, balance, etc.
Wire-wound potentiometers are used in devices which require more
accuracy in control. They feature higher dissipation than coated pots, and are
therefore in high current circuits.
Potentiometer resistance is commonly of E6 series, including the values:
1, 2.2 and 4.7. Standard tolerance values include 30%, 20%, 10% (and 5% for
wire-wound pots).
Potentiometers come in many different shapes and sizes, with wattage
ranging from 1/4W (coated pots for volume control in amps, etc) to tens
ofwatts(for regulating high currents). Several different pots are shown in the
photo 5.7.b, along with the symbol for a potentiometer.
Fig. 5.7(e): Potentiometers
The upper model represents a stereo potentiometer. These are actually
two pots in one casing, with sliders mounted on shared axis, so they move
simultaneously. These are used in stereophonic amps for simultaneous
regulation of both left and right channels, etc.
Lower left is the so called slider potentiometer. Lower right is a wirewound pot with a wattage of 20W, commonly used as rheostat (for regulating
current while charging a battery etc.).
For circuits that demand very accurate voltage and current values,
trimmer potentiometers (or just trim pots) are used. These are small
potentiometers with a slider that is adjusted via a screwdriver.
Trim pots also come in many different shapes and sizes, with wattage
ranging from 0.1W to 0.5W. Image 5.7.c shows several different trim pots,
along with the symbol.
Fig. 5.7(f): Trim potentiometers
Resistance adjustments are made via a screwdriver. Exception is the trim
pot on the lower right, which can be adjusted via a plastic shaft. Particularly fine
adjusting can be achieved with the trim pot in the plastic rectangular casing
(lower middle). Its slider is moved via a screw, so that several full turns is
required to move the slider from one end to the other.
5.7.2 Practical examples with potentiometers:
As previously stated, potentiometers are most commonly used in amps,
radio and TV receivers, cassette players and similar devices. They are used for
adjusting volume, tone, balance, etc.
As an example, we will analyze the common circuit for tone regulation in
an audio amp. It contains two pots and is shown in the figure 5.7.d.
Fig. 5.7(g) Tone regulation circuit: a. Electrical scheme, b. Function of
amplification
Potentiometer marked BASS regulates low frequency amplification.
When the slider is in the lowest position, amplification of very low frequency
signals (tens of Hz) is about ten times greater than the amplification of mid
frequency signals (~kHz). If slider is in the uppermost position, amplification of
very low frequency signals is about ten times lower than the amplification of
mid frequency signals. Low frequency boost is useful when listening to music
with a beat (disco, jazz, R&B...), while Low Frequency amplification should be
reduced when listening to speech or classical music.
Similarly, potentiometer marked TREBLE regulates high frequency
amplification. High frequency boost is useful when music consists of highpitched tones such as chimes, while for example High Frequency amplification
should be reduced when listening to an old record to reduce the background
noise.
Diagram 5.7.d. shows the function of amplification depending upon the
signal frequency. If both sliders are in their uppermost position, the result is
shown with curve 1-2. If both are in mid position function is described with line
3-4, and with both sliders in the lowest position, the result is shown with curve
5-6. Setting the pair of sliders to any other possible results in curves between
curves 1-2 and 5-6.
Potentiometers BASS and TREBLE are coated by construction and linear
by resistance.The third pot in the diagram is a volume control. It is coated and
logarithmic by resistance (hence the mark log)
Chapter 6
Project design
6.1 Software design:
I found my dew sensor circuit and heater circuit from the internet as I said
in the above chapter.I have made my complete project on a special purpose
PCB.
I prepared the layout of both of these circuits using dip trace software.I
learned dip trace software in my college. Then I installed the software from the
internet and started working on it. Given below is he detailed description on dip
trace software.
6.1.1 Dip trace:
Dip Trace is EDA software for creating schematic diagrams and printed circuit
boards. The first version of Dip Trace was released in August, 2004. The latest
version as of September 2011 is Dip Trace version 2.2. Interface has been
translated to many languages and new language can be added by user. There are
tutorials in English, Czech, Russian and Turkish. Starting from February 2011
Dip Trace is used as project publishing standard by Parallax.
Modules

Schematic Design Editor

PCB Layout Editor

Component Editor

Pattern Editor

Shape-Based Auto router

3D PCB Preview
Freeware and Non-Profit versions
A version of Dip Trace that is freely available with all the functionality of
the full package except it is limited to 300 pins and 2 signal layers.
Other sources

Dip Trace at Seattle Robotics Society meeting

Dip Trace at Nuts and Volts – October 2006

Review at C Net
Some hobby and educational groups such as the PICAXE forum members
have developed libraries specific to the PICAXE range of microcontroller as
produced by Revolution Education including many of the frequently used
associated integrated circuits. PICAXE related libraries can be found here:
 DIP TRACE Libraries by and for PICAXE microcontroller users
External links

Dip Trace official Website in English

Dip Trace Website in Italian

Dip Trace Website in Turkish

Novarm Ltd. Official Website in English
6.2 Hardware design:
The hard\ware design ofboth the circuit of the project i.e. DC motor
speed control using PWMcircuit includes their block diagrams and list of the
components used in these circuits.
PCB Layout:
Fig 6.1 PCB Layout
6.2.1 PCB designing steps:
The most important requirement of this project was to build a PCB with
minimum weight and size.
A zero PCB is a drilled board drilling process removes a lot of material
from board, and the weight is reduced. Designing method is as follows.
1. Decide proper places for components.
2. Actual placement of component on zero PCB.
3. Connecting tracks with solid wires.
4. Testing for continuity and debugging.
One PCB designed in this project. PCB are constructed on simple zero
PCB and interconnection of components was done by single stander wire.
PCB MANUFACTYRING:
STEP 1 (MASTER ART WORK AND MAKE PCB CIRCUIT)
 Draw the master art work. It maybe drawn 4 to 30 times larger than its
final expected size of the board
 Place component and make actual circuit in diptrace program file.
STEP 2 (MAKE UP PHOTOGRAPHY)
 Print the project circuit on photo paper by use the laser printer.
STEP 3 (CLEAN OF LAMINATE)
 Clean the copper clad laminate using solvent like Tri Chloro ethylene.
 And then wash it with water and dry the pcb by use of dry paper.
STEP 4 (TRANSFER PCB LAYOUT ON CIRCUIT)
 Transfer bottom layout of circuit which we make in diptrace by use of
cloth press.
STEP 5 (DRYING THE IMAGE)
 Immerse the board into the for about 10-20 sec. remove the board and
wash it under spray of water.
STEP 6 (ETCHING)
 Immerse the board in FeCl3 solution (40-60 in) for etching unwanted
copper portion.
STEP 7 (RESIST REMOVER)
 Wash the board under running water and remove the resist from image
area with solvent like Tri Chloro Ethylene.
STEP 8 (DRILLING)
 Drill the fabricated PCB for mounting component.
STEP 9 (MOUNTING COMOPONENT)
 Place all component of circuit on circuitproperly.
STEP 10 (SOLDRING)
 Solder the all component by use of soldering iron.
 Use flux to make up proper soldering.
STEP 11 (CIRCUIT TESTING)
 Test the circuit soldering by use of multimeter.
Chapter 7
Component Testing
7.1 RESISTER TESTING:
1. Select the appropriate function button from multimeter.
2. Select the required range scale on rotary switch.
3. Place the resister between terminals of meter.
4. Observe and note the reading.
5. LCR meter can also be used for this purpose.
NOTE:- WE CAN ALSO KNOW THE RESISTER BY THE COLORSOF THE
RESISTER
4 Band Resister Color Codes:-
Table 1. 4 Band Resister Color Codes:-
The Formula For Four Band Resistor:(First Band + Second Band) * Third Band = Total
7.2 CAPACITOR TESTING:
1. Select the appropriate function button from multimeter.
2. Select the required range scale on rotary switch.
3. Place the capacitor between terminals of meter.
4. The capacitor voltage will appear on the screen and suddenly start
decreasing due to discharging of this capacitor.
6. LCR meter can also be used for this purpose.
Chapter 8
Advantages and Application
8.1
Advantages:
 The main advantages of this project is it is not expensive compare to
other.
 It provide perfect detection of gas leakage with suitable audio as well as
light indication.
8.2 Application
 Protection from any gas leakage in cars.
 For safety from gas leakage in heating gas fired appliances like boilers,
domestic water heaters
 For safety from gas leakage in Cooking gas fired appliances like ovens,
stoves etc
 Large industries which uses gas as their production.
 They are used in gas leakage detecting equipment’s in family, Car and
industry, are suitable for detecting of LPG, iso-butane, propane, LNG,
avoid the noise of alcohol and cooking fumes and cigarette smoke
Chapter 9
Data sheet
9.1 zener diode:
This data sheet provides information on sub miniature size, axial
lead mounted rectifiers for general−purpose low−power applications.
Features: Give stable output voltage.
 Small size and weight
 It is reliable
 Lowest price.
 Small Package : SOT-23
 Normal Voltage Tolerance About ᴦ2.5%.
Maximum Ratings:
CHARACTERISTIC
SYMBOL
RATING
UNIT
Power Dissipation
PD
200
mW
Junction Temperature
Tj
150
ᴱ
Tstg
-55ᴕ150 ᴱ
°C
Storage Temperature Rang
9.1 Table of Maximum Ratings
9.2 IC 555:
The555 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
one external resistor and capacitor. For astable operations an oscillator, the free
running frequency and the duty cycle are both accurately controlled with two
external resistors and one capacitor.
The circuit may be triggered and reset on falling waveforms, and the
output structure can source or sink up to 200mA. The NE555 is available in
plastic and ceramic mini dip package and in a 8-leadmicropackage and in metal
Advantages: Low turn off time
 maximum operating frequency greaterthan 500khz .
 timing frommicro seconds to hours

operates in both astable and monostable modes
 high output current can source or sink 200ma
 adjustable duty cycle
 ttl compatible
 temperature stability of 0.005% per Celsius
Application:
 Use to performnonostable operation.

Use to perform astable operation.
Maximum Rating:
Symbol
Vcc
Parameter
Value
Unit
18
V
0 to 70
°C
150
°C
-65 to 150
°C
Supply voltage
T oper
Operating free air temperature
Tj
Junction temperature
Tstg
Storage temperature range
9.2 Table of Maximum Rating of ic555
9.3 SL100 TRANSISTOR:
Polarity:
NPN
Application: general purpose medium power transistor
Package:
TO – 39
CHARACTERISTIC
SYMBOL
MIN
MAX
UNIT
50
-
V
BV CEO
60
-
V
BV CEO
0.5
-
V
800
mW
Collector –emitter
voltage
BV CEO
Collector – Base
voltage
Emitter – Base Voltage
Total Power
Dissipation
Pd
Collector current
Operating & Storage
Ic
0.5
A
Tj , Tstg
-65 to 200
°C
Junction Temperture
9.3 Maximum rating of SL100
9.4 MQ-6 SENSOR:
Structure and configuration of MQ-6 gas sensor is shown as
Fig.(Configuration A or B), sensor composed bymicro AL2O3 ceramic tube,
Tin Dioxide (SnO2) sensitive layer, measuring electrode and heater are fixed
into acrust made by plastic and stainless steel net. The heater provides necessary
work conditions for work of
sensitive components. The enveloped MQ-6 have 6 pin ,4 of them are
used to fetch signals, and other 2 are usedfor providing heating current.
FEATURES:* High sensitivity to LPG, iso-butane, propane
* Small sensitivity to alcohol, smoke.
* Fast response.
* Stable and long life
* Simple drive circuit
APPLICATION:-
They are used in gas leakage detecting equipments in family and industry,
are suitable for detecting ofLPG, iso-butane, propane, LNG, avoid the noise of
alcohol and cooking fumes and cigarette smoke.
SENSITVITY ADJUSTMENT: Resistance value of MQ-6 is difference to various kinds and various
concentration gases. So, When using
 this components, sensitivity adjustment is very necessary. we recommend
that you calibrate the detector for
 1000ppm of LPG concentration in air and use value of Load resistance (
RL) about 20KΩ(10KΩ to 47KΩ).
 When accurately measuring, the proper alarm point for the gas detector
should be determined after considering the temperature and humidity
influence.
Chapter 10
Daily schedule
Daily schedule:
MONTH
WORK DONE
July
Made our visit to bath touch industry found the problem
in weldmachine drive by gas.
July-August
Found the solution in the web sites and other reference
book
August
Found datasheet and start making circuits.
August-September prepared layout, started mounting and fabricated device
September-
Successfully completed the model and started preparing
October
report
November
Completed the report and prepared the presentation
10.1 Daily Schedule
Reference:
1. Electronic Device & Circuit
J.B.Gupta
2. Principal of ElectronicsV.K.Mehta
3. Electronic For You
4. Website www.google.com
www.projectcircuit.com,www.datasheetarchive.com
www.answer.com ,www.wikipedia.com, www.hobbyprojects.com
Conclusion
Thus by using this project the gas leakage detected fast and reduced
accident possibilities. This project is also cheap and can be used on large scale.
One more is by adding programming IC and more component we get automatic
turn on/off control by human voice.