S. E. PROJECT REPORT ON

SMOKE DETECTOR

(Analog Project)

SUBMITTED BY

ASHWINI NAYAK DIKSHA RAUT

TANVI REVANDKAR

ELECTRONICS ENGINEERING

ATHARVA COLLEGE OF ENGINEERING, MUMBAIUniversity of Mumbai

2009-2010

CERTIFICATE

This is to certify that the Project ‘SMOKE DETECTOR’ has been carried out by ‘ASHWINI NAYAK’, ‘DIKSHA RAUT’,‘TANVI REVANDKAR’ who are bonafide students of ATHARVA COLLEGE OF ENGINEERING, Mumbai, in partial fulfillment of the requirement of S. E. Degree in Electronics Engineering of Mumbai University. The work has not been presented anywhere else for award of any other degree or diploma prior to this.

Internal Examiner External Examiner

_________________________ __________________________ ( PRACHITI GHARAT ) ( )

I

ACKNOWLEDGEMENTS

We would like to express our sincere thanks to Ms Prachiti Gharat for taking time

from her busy schedule to provide us with great deal of help, support and encouraged us to

work diligently at every aspects of our project. Her views have always been equitable striking

perfect balance between encouragement and constructive criticism. Her constructive tips and

suggestions helped us to successfully do the project. We have benefited a lot from her

immense knowledge and experience.

We are thankful to our college director, Principal Dr.Anupama Deshpande, ELEX

HOD Prof.Archana Chaudhari and all staff members of Electronics and Telecommunications

department who have provided us various facilities and have guided us whenever required.

. Our project at various stages has entailed us to seek help from variety of individuals

we would like to thank each one of them for their forbiddance and guidance.

Finally we would like to thank our parents and our friends for constantly supporting

and encouraging our efforts.

We would like to thank Microsoft Word & Microsoft Paint for providing us various

Fonts to represent our project report more effectively & in an impressive way.

ASHWINI NAYAK

DIKSHA RAUT

TANVI REVANDKAR

II

CONTENTS

Abstract................................................................................................................................................ 1

1.Introduction....................................................................................................................................... 2

2.Smoke Detector Section.................................................................................................................... 5

2.1 Block Diagram............................................................................................................................. 5

2.2 Block Diagram Explanation.......................................................................................................... 6

2.2.1 LDR...................................................................................................................................... 6

2.2.2 Transistor............................................................................................................................. 6

2.2.3 +5V Voltage Regulator........................................................................................................ 7

2.3.Component Description.............................................................................................................. 10

2.3.1 LED.................................................................................................................................... 10

2.3.2 100k Potentiometer............................................................................................................ 13

2.3.3 LDR(Light Dependent Resistor)........................................................................................15

2.3.4 Transistor BC107............................................................................................................... 18

2.3.5 IC7805................................................................................................................................ 22

3.Alarm Section.................................................................................................................................. 24

3.1 Block Diagram........................................................................................................................... 24

3.2 Block Diagram Explanation....................................................................................................... 25

3.2.1 Melody Generator.............................................................................................................. 25

3.2.2 Amplifier............................................................................................................................ 25

3.2.3 Speaker............................................................................................................................... 26

3.3. Component Description............................................................................................................. 29

3.3.1 Diode 1N4007.................................................................................................................... 29

3.3.2 IC UM66............................................................................................................................ 33

3.3.3 100k Potentiometer............................................................................................................ 35

III

3.3.4 IC TDA2002....................................................................................................................... 38

3.3.5 Resistors & Capacitors....................................................................................................... 42

3.3.6 Speaker............................................................................................................................... 42

4.Circuit Diagram Explanation........................................................................................................ 44

5.Printed Circuit Board ........................................................................................................................48

6.Softwares Used ............................................................................................................................... 54

6.1Keil Compiler.............................................................................................................................. 54

6.2 Visual Basic 6............................................................................................................................ 58

6.3.ORCAD...................................................................................................................................... 67....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... 66............................................................................................................................................................

7.Result And Discussion ......................................................................................................................68

7.1Application.................................................................................................................................. 68

7.2 Advantages................................................................................................................................. 69

7.3 Disadvantages ........................................................................................................................... 70

8.Conclusion............................................................................................................................................72

9.References.............................................................................................................................................73

IV

IV

LIST OF FIGURE AND TABLES

Figure 2.1 Block diagram of smoke detector section..................................................................

Figure 2.2 Light dependent resistance.........................................................................................

Figure 2.3 Transistor BC107.......................................................................................................

Figure 2.4 +5V voltage regulator IC7805...................................................................................

Figure 2.5 Light Emitting Diode (LED)......................................................................................

Figure 2.6 100k Potentiometer....................................................................................................

Figure 2.7 Light dependent resistance.........................................................................................

Figure 2.8 Internal block digram of power supply......................................................................

Figure 2.9 Pin Diagram of IC 7805 ............................................................................................

Figure 3.1 block diagram of alarm section..................................................................................

Figure 3.2Melody generator ICUM66.........................................................................................

Figure 3.3 Amplifier IC TDA2002.............................................................................................

Figure 3.4 Speaker......................................................................................................................

Figure 4.1 Circuit diagram of smoke detector ............................................................................

Figure 6.1Translate schematic of PBC........................................................................................

Figure 6.2Screen with unplaced components..............................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

Table...........................................................................................................................................

V

ABSTRACT

A stitch in time saves nine. Our project ‘Smoke Detector and Fire Alarm Circuit’ works

as a security measure.

Smoke Detector helps in the early detection of fire breakout. It thus helps to prevent any

potential impending threat to precious life and damage to infrastructure of property due

to a major fire breakout. The detector detects the smoke emanating from fire. The inbuilt

fire alarm , lets out a sound alert to warn of the fire. The early detection gives sufficient

time for the inhabitants of a residential or commercial buildings to evacuate the place

urgently and quickly thus saving lives.

INTRODUCTION

The first automatic electric fire alarm was invented in 1890 by Francis Robbins Upton.

It was 30 years, however, before progress in nuclear chemistry and solid-state electronics

made a cheap sensor possible. Before that, alarms were so expensive that only major

businesses and theaters could afford them.

The first truly affordable home smoke detectors were invented in 1965, featuring

individual battery powered units that could be easily installed and replaced.

Conventional smoke detectors are so called because they are the older type of smoke

detectors. The detector communicates with the fire alarm control panel simply by

changing state from high impedance to low impedance when smoke is detected.

The smoke is detected by an optical sensor . An optical detector is a light sensor. When

used as a smoke detector, it includes a light source (incandescent bulb or infrared LED), a

lens to collimate the light into a beam, and a photodiode or other photoelectric sensor at

an angle to the beam as a light detector. In the absence of smoke, the light passes in front

of the detector in a straight line. When smoke enters the optical chamber across the path

of the light beam, some light is scattered by the smoke particles, directing it at the sensor

and thus triggering the alarm.

Also seen in large rooms, such as a gymnasium or an auditorium, are devices to detect a

projected beam. A unit on the wall sends out a beam, which is either received by a

receiver or reflected back via a mirror. When the beam is less visible to the "eye" of the

sensor, it sends an alarm signal to the fire alarm control panel.

Optical smoke detectors are quick in detecting particulate (smoke) generated by

smoldering (cool, smoky) fires. Many independent tests indicate that optical smoke

detectors typically detect particulates (smoke) from hot, flaming fires approximately 30

seconds later than ionization smoke alarms.

They are less sensitive to false alarms from steam or cooking fumes generated in kitchen

or steam from the bathroom than are ionization smoke alarms.

Smoke detectors are one of those amazing inventions that, because of mass production,

cost practically nothing. And while they cost very little, smoke detectors save thousands

of lives each year.

2 SMOKE DETECTOR SECTION

2.1 Block Diagram

Fig 2.1 Block diagram of smoke detector section

LDR

TRANSISTOR

+5V VOLTAGE REGULATOR IC

LIGHT INPUT

OUTPUT TO FIRE ALARM SECTION

2.2 BLOCK DIAGRAM EXPLANATION

2.2.1 LDR

Fig 2.2 Light dependent resistance

1. A LDR or photo-resistor is an electronic component whose resistance decreases with the increasing incident light intensity.

2. It can also be referred to as a photoconductor.

3. It is made of a high-resistance semiconductor.

4. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band.

5. The resulting free electron (and its hole partner) conduct electricity, thereby lowering resistance.

6. If the intensity of the light incident on LDR is changed or varied, the resistance of the LDR varies.

7. According to the incident light input for the LDR, for the decrease in the intensity of the light, LDR resistance increases.

8. With the increase in the LDR resistance, voltage drop across the resistor increases & hence the Voltage at the LDR terminal connected to the transistor becomes sufficient to produce the current which can make the transistor ON.

2.2.2 TRANSISTOR

BC107 low-current NPN bipolar transistor TO18 can Collector connected to can

Emitter marked with a tag on the edge of the can Ic <= 100mA; 300mW; Vceo <= 45V

Fig 2.3 Transistor BC107

1. As the Voltage at the base of the transistor becomes sufficient to bias it in work in

the forward active region transistor becomes ON.

2. This provides energy to the Voltage regulator circuit.

2.2.3 +5V Voltage Regulator

Fig 2.4 +5V Voltage regulator IC 7805

1. As the transistor output becomes sufficient to supply energy to the Voltage

Regulator , Voltage Regulator starts working.

2. It regulates its input voltage and gives the output of value +5V.

3. This +5V Voltage output is then given to the alarm Circuit.

2.3 COMPONENT DESCRIPTION

2.3.1 LED

Fig 2.5 Light Emitting Diode (LED)

Data Specifications

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices, and are increasingly used for lighting. Introduced as a practical electronic component in 1962,[2] early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet and infrared wavelengths, with very high brightness.

The LED is based on the semiconductor diode. When a diode is forward biased (switched on), electrons are able to recombine with 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. An LED is usually small in area (less than 1 mm2), and integrated optical components are used to shape its radiation pattern and assist in reflection.[3] LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and greater durability and reliability. However, they are relatively expensive and require more precise current

and heat management than traditional light sources. Current LED products for general lighting are more expensive to buy than fluorescent lamp sources of comparable output.

They also enjoy use in applications as diverse as replacements for traditional light sources in automotive lighting (particularly indicators) and in traffic signals. Airbus uses LED lighting in their A320 Enhanced since 2007, and Boeing plans its use in the 787. The compact size of LEDs has allowed new text and video displays and sensors to be developed, while their high switching rates are useful in advanced communications technology.

2.3.2 100k Potentiometer

Fig 2.6 100K Potentiometer

Specification Value

Family RV4

Minimum Operating Temperature

-55°C

Mounting Panel Mount

Shaft Diameter 6.35mm

Product Length 36.52mm

Product Diameter 27.78mm

Product Type Resistor Trimmers, Potentiometer and Rheostat

Resistance Value 100KOhm

Power Rating 2W

Tolerance 10%

Termination Style Solder Lug

Maximum Operating Temperature 120°C

2.3.3 LDR

Fig.2.7 Light dependent resistance

FEATURES:

Epoxy Encapsulated

Small size

Reliable performance

Quick response

High sensitivity

Good characteristic of spectrum

APPLICATIONS:

Auto flash for cameras

Industrial control

Photoelectric control

Photo switch

Room light control

Photo lamp

Electronic toys

Photomusical IC

DIAMETER:

4mm

5mm

7mm

12mm

20mm

2.3.4 Transistor BC107

BC107VCEO Collector – Emitter Continuous Voltage With Zero Base Current

BC107 30 V

VCES Collector – Emitter Continuous Voltage With Base Shortcircuited to Emitter

BC107 45 V

VEBO Emitter – Base Continuous Voltage Reverse Voltage

BC107 20 V

IC Continuous Collector Current BC107 100mA

ICM Peak Collector Current BC107 200mA

Ptot Power Dissipation @ Tamb

= 25°CBC107 300mW

Tamb Ambient Operating Temperature Range

BC107 -65 to +175°C

Tstg Storage Temperature Range

BC107 -65 to +175°C

Noise Factor VCE = 5V IC = 0.2mAR = 2kf =1kHz F=200Hz BC 107 Max 10 dB

Output Admittance VCE = 5V IC = 2mA f = 1kHz

Group A BC107 Min 1.6kax 4.5 kInput Impedance VCE = 5V IC = 2mA f = 1kHz

Group A BC107Max 30 S

Thermal Resistance: Junction to Ambient

BC 107 Max 500 °C/W

2.3.5 IC 7805

Fig.2.8 Internal Block Diagram of POWER SUPPLY

2.3.5.1 Features

Output current in excess of 1A

Internal thermal overload protection

No external components required

Output transistor safe area protection

Internal short circuit current limit

Available in the aluminum TO-3 package

2.3.5.2 Pin Diagram

Fig 2.9 Pin diagram of IC 7805

3 ALARM SECTION

Block Diagram

Fig 3.1 Block diagram of alarm section

MELODY GENERATOR IC

AMPLIFIER IC

AMPLIFIED SIGNAL

INPUT FROM SMOKEDETECTOR

BLOCK DIAGRAM OFALARM

SPEAKER

3.2 Block Diagram Explanation

3.2.1 Melody Generator

Fig 3.2 Melody generator IC UM66

1. Output from +5V Voltage Regulator is given to the Melody Generator which generates

an Audible frequency output.

2. This output is then given to the amplifier circuit for the amplification.

3.2.2 Amplifier

Fig 3.3 Amplifier IC TDA2002

1.Amplifier amplifies the signal and its output is then given to the speaker.

3.2.2 Speaker

Fig 3.4 Speaker

1. Output of the amplifier is given to the speaker.

2. Speaker converts the output in the form of voltage to the output in the

form of Audible signal.

3.3 Component Description

3.3.1 Diode 1N4007

Maximum Recurrent Peak Reverse Voltage 1000V

Maximum RMS Voltage 700V

Maximum DC Blocking Voltage 1000V

Peak Forward Surge Current 8.3ms singlehalf sine-wave superimposed on rated load

30A

Maximum Forward Voltage at 1.0A DC 1.1V

Maximum Reverse Current at TA=25 ¢JAt Rated DC Blocking Voltage TA=100 ¢J

5.0A

500A

Typical Junction capacitance 15pF

Typical Thermal Resistance 50¢J /W

Typical Thermal resistance 25¢J /W

Operating and Storage Temperature Range -55 to +125 ¢J

3.3.2 UM66

3.3.3 100K potentiometer

Category Potentiometers

Resistance In Ohms 100K

Power (Watts) 0.75W, 3/4W

Number of Turns Single

Package / Case Round - 0.531" Dia x 0.268" H (13.50mm x 6.80mm)

Adjustment Type Top Adjustment

Tolerance ±10%

Mounting Type Through Hole

Temperature Coefficient ±50ppm/°C

Resistive Material Wire wound

3.3.4 IC TDA 2002

4. CIRCUIT DIAGRAM EXPLANATION

Description.

Here is a simple fire alarm circuit based on a LDR and lamp pair for sensing the fire.The alarm works by sensing the smoke produced during fire.The circuit produces an audible alarm when the fire breaks out with smoke.

When there is no smoke the light from the bulb will be directly falling on the LDR.The LDR resistance will be low  and so the voltage across it (below .6V).The transistor will be OFF and nothing happens.When there is sufficient smoke to mask the light from falling on LDR, the LDR resistance increases and so do the voltage across it.Now the transistor will switch to ON.This gives power to the IC1 and it outputs 5V.This powers the tone generator IC UM66 (IC2)  to play a music.This music will be amplified by IC3 (TDA 2002) to drive the speaker.

The diode D1 and D2 in combination drops 1.4 V to give the rated voltage (3.5V ) to UM66 .UM 66 cannot withstand more than 4V.

Circuit diagram with Parts list.

Fig 4.1 Circuit diagram of smoke detector circuit

Notes. 

The speaker can be a 8Ω tweeter.  POT R4 can be used to adjust the sensitivity of the alarm. POT R3 can be used for varying the volume of the alarm. Any general purpose NPN transistor(like BC548,BC148,2N222) can be used for Q1. The circuit can be powered from a 9V battery or a 9V DC power supply. Instead of bulb you can use a bright LED with a 1K resistor series to it.

5. PRINTED CIRCUIT BOARD

P.C.B. Construction

A Printed Circuit Board (P.C.B.) can be defined as an insulating base material to which

is permanently attached a flat metallic network of conducting paths whose dimension

depends upon the current that can be handled by them. The P.C.B. may be either single

sided or double sided. The P.C.B. used for this project is single sided one.

The basic material used may be resin coated papers, fiber glass, ceramic and the flat board

configuration however is most widely used and it may be of the nature of the single “Mother

Board” into which smaller boards are plugged by the especially designed connectors which

ensures adequate and permanent low resistance coupling.

Board Design:

PCB designing is the most important and requires great care during work. In this case

great care must be taken while tracing the circuit or layout on the board. Because once PCB is

designed, it is virtually impossible to alter it. While designing a circuit, designer should take

care to avoid crossing of conducting paths (tracks) as possible. Crossovers are unavoidable

then only of the jumper can be used. A circuit board carrying copper on both sides can also

help to solve this problem when circuit is complicated.

The Master Diagram

The next stage lies in proportion to designing i.e. to prepare “Master Diagram”, which is

commonly made twice as the finished circuit, since this makes the working on that much

easier, especially when circuit is complicated photography eventually reduces the size of

diagram to that of the circuit, before proceeding we must know some rules regarding the

designing:-

1) The space between the conductors must be strictly controlled to avoid the possibility

of electrical discharge or unwanted capacitance. The amount by which the master

diagram is to reduce in size is thus a critical design feature.

2) The conductor must be wider in those parts of the circuits that are going to handle

large currents must be handle without undue temperature of conductors.

3) The minimum width of copper should not generally be less than about 1.5mm. This is

related to mechanical strength rather than electrical properties and it also ensures that

strips remains securely bounded to the base material.

4) The points where the component holes for component lead wire occurs must be sited

to suit the dimensions of the component and dimensions between lead-out wires, so

that, the components can be situated correctly on finished board. The conductor is

also large at the point of holes.

P.C.B. Making:

When the master diagram probable twice the size of real PCB has been evolved, the text

major step consists of etching or dissolving the unwanted metal from copper claded board to

create the circuit as depicted by master diagram. It must be stressed that very accurate

checking of master is essential at this stage. Then, the master point is mounted on a special

frame on easy facing of a larger camera and with the aid of the very powerful illumination a

master diagram is clearly photographed on a glass sensitive plate. This is developed to give

photographic negative. Next so called “step and repeat camera” is brought into operation.

This comprises the camera body mounted so that side ways after each exposure. In this way

number of copies of the original master diagram is set out exactly to cover standard sheet of

copper clad laminate laboratory method of making PCB.

In case of simple and need of number of less PCB’s, it is economic and advisable to use

the following lab method of PCB making:-

Planning the circuit:

Though this is not particularly difficult, there are several important factors that need not

be taken into account. If the finished device is to work properly we must consider gain factor

and ensure that the input and output parts are sufficiently well isolated to avoid the

possibility. We must also ensure that conductors and components carrying high frequency

current are well separated from these parts of the circuits. We are also to make sure that all

components need to return to earth are properly connected and that possibility of common

impedance arising in earth returned. Circuit is totally eliminated by making all earth as

substantial as possible consistent with nature of design. Other factors that have to

successfully studied include availability of adequate return points on board and it’s

mounting from accessibility of switch connections made for mechanical fixing ventilation

effect of vibration.

Cleaning the board:

The copper side of the board must be thoroughly cleaned before Circuit plan is transferred

to it. This is very important because even slightest trace of graze (from figure of instance)

will impure the etching process and when the circuit plan has been neatly transferred to

copper in this manner the board is held under, running tap and the allowed to dry before resist

is applied.

Transforming the plan:

Now, once cleaning is done plan has to transfer on copper surface of PCB material.A

convenient way to do this is simply put a carbon paper between a copper surface of the board

and working plan and carefully trace the lines of original plan with a ball pen.

Resist:

Resist is nothing more than a substrate that is unaffected by presence etching chemicals. It

is usually colored so that, it can be easily seen the copper surface. When plan is clearly

worked on clean copper the a that are to be left in fact as the copper conductors must be

covered when resists the leaguer type of paints possess good resist properties but

disadvantages of relatively long time taken for drying. It is essential to resist through

hardening before etching is started. Nail polished are better as they quickly and are less

difficult to remove.

To overcome this drying effect and to achieve the sharp edges of the trace on PCB. Now a

days etching taps along with IC pads are commonly used. To this, chances of short

circulating due to paints are completely the avoid etching tapes and pads are available in

different sizes.

Correcting errors:

When a result has been thoroughly hardened any errors that have been made can usually

be corrected by gently scratching away with knife. To ensure clear out lines round edges of

copper conductors on board the resist must be applied with steady band.

Etching:

Next comes etching of unwanted copper and whether a small single is all that is required

as quantity of board to be produce certain precautions must be taken before operation is

commenced the most used etch ant I ferric chloride and to this is added small quantity of HCL

to accelerate. But it is not as critical as lab construction is concerned. Mixing 10 grams of

ferric chloride and 25 grams of HCL with 15 grams of water can produce a good etchant.

Agitation:

Small plastic bath is ideal for storing the etchant process. The Depth of liquid must be

sufficient to completely cover laminate, the laminated board carrying the resist pattern circuit

is then dropped into etchant bath and the gentle agitation takes 5 to 20 minutes to complete

depending on the strength of the enchant temperature and thickness of copper foil.

Finishing off:

When all unwanted copper is dissolved from areas between conductors, board should be

taken from an etchant and washed in water. The resist must be removed using proper solvent.

After this the copper surface must be polished with any kind of cleaner. It should be seen that

there is no slight incomplete etching between the conducting paths of the PCB. The PCB’s are

coated coating material for protection in lab coating material itself is a soldier. This process is

called Tinning. This process of coating involves tracks with solder. Advantage of tinning the

effect of environment of conductors, then PCB is drilled i.e. holes for filling and mounting the

components on PCB are drilled with suitable drill bit.

Assembling of PCB:

After the holes are drilled, the components have to be assembled On PCB before

assembling the components it is necessary to clean soldering iron in order to get easy and

accurate soldering. Removing impurity particles that are gathered on iron bit due to repetitive

use cleans soldering iron.

6. SOFTWARES USED

Here are the steps for PCB design [19]

1. Make schematic diagram using PCB Artist.

2. Once you finish schematic design translate it to PCB by using

Fig. 6.1 Translate Schematic to PCB

3. This will display new PCB wizard. Board parameter is set by default use the same one

or change as per requirement.

4. You will see the board outline ready to place the components in. We previously chose

to leave the components unplaced and the nets unrouted.

5. The board outline is displayed with the components stacked neatly at the top edge

ready for placing.

Fig.6.2 Screen with unplaced components

6. Now place component as per requirement, place is simple case of picking and dragging

the selected component.

7. After placing components pour copper by selecting Pour copper option. This will help

to get the tracks.

7. RESULT & DISCUSSION

8.CONCLUSION

9.REFERENCES