PROJECT REPORT ON

FIRE ALARM USING 555 TIMER IC

Submitted by

XYZ

UNDER THE GUIDANCE OF

DEPARTMENT OF ELECTRONICS ENGINEERING

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PROJECT CERTIFICATEThis is to certify that, the project title,

FIRE ALARM USING 555 TIMER IC .

IS SUCCESSFULLY COMPLETED BY .

.

In partial fulfillment of degree course in TE. ELECTRONICS ENGINEERING as

Prescribed by MUMBAI UNIVERSITY DURING ACADEMIC YEAR 2014-2015

UNDER THE GUIDANCE OF

PROF .

DATE OF SUBMISSION _______________________________________

PROJECT GUIDE HEAD OF DEPARTMENT

( ) ( )

PRINCIPAL

( )

INTERNAL EXAMINER EXTERNAL EXAMINER

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PREFACE

We take an opportunity to present this project report on “FIRE ALARM USING 555 TIMER IC” & put before readers some information regarding our project.

We have made sincere attempts & taken every care to presentthis matter in precise & compact form, the language being as simple as possible.

We are sure that the information contained in this volume would certainly prove useful for better insight in the scope and dimension ofthis project in its true perspective.

The task of completion of this project through being difficult was made quite simple, interesting & successful due to deep involvement & complete dedication of our group members.

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CONTENTS

. . .

Sr.No

Topics Page No.

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1. Acknowledgement 52. Introduction To The Project 63. Block diagram 84. Working 135. Components Required 176. Methodology 187. PCB Layout 20 8. Troubleshooting 219. Advantages 2210. Disadvantages 23 11. Application 24 12. Conclusion 25 13. Bibliography 26

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ACKNOWLEDGEMENT

It is indeed a matter of great pleasure and proud privilege to be able to present this project on “FIRE ALARM USING 555 TIMER IC”.

The completion of this project work is a milestone in students life and its execution is inevitable in the hands of guide. We are highly indebtedthe project guide for her invaluable guidance & appreciation for giving form and substance to this report. It is due to her enduring efforts, patience & enthusiasm, which has given a sense of direction and purposefulness to this project and ultimately made it success.

We would like to tender our sincere thanks to the staff members for their co-operation.

We would also like to express our deep regards and gratitude to the Principle Prof. .

We would wish to thank the non-teaching staff and our friends whohave helped us all the time in one way or other.

Really it is highly impossible to repay the debt of all the people who have directly or indirectly helped us for performing the project.

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INTRODUCTION TO THE PROJECT

This is a simple fire alarm circuit using Germanium Diode and 555 timer. In this circuit Germanium Diode play very important role indetecting the fire.

This circuit is very easy to construct, cost effective and implementable. An automatic fire alarm system is designed to detect the unwanted presence of fire by monitoring environmental changes associated with combustion.

In general, a fire alarm system is either classified as automatic, manually activated, or both. Automatic fire alarm systems can be used to notify people to evacuate in the event of a fire or other emergency, to summon emergency services, and to prepare the structure and associated systems to control the spread of fire and smoke.

Fire alarm systems have become increasingly sophisticated and functionally more capable and reliable in recent years. They are designed to fulfil two general requirements: protection of property andassets and protection of life. As a result of state and local codes, the life-safety aspect of fire protection has become a major factor in the last two decades

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There are a number of reasons for the substantial increases in the life- safety form of fire protection during recent years, foremost of which are :

1. The proliferation of high-rise construction and the concern for life safety within these buildings.

2. A growing awareness of the life-safety hazard in residential, institutional, and educational occupancies.

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BLOCK DIAGRAM

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GERMANIUM DIODE

The 1N4148 is a standard silicon switching diode. It is one of the most popular and long-lived switching diodes because of its dependable specifications and low cost.

Its name follows the JEDEC nomenclature. The 1N4148 is useful in switching applications up to about 100 MHz with a reverse-recovery time ofno more than 4 ns.The 1N4148 comes in a DO-35 glass package for thru-hole mounting. This is useful forbreadboarding of circuits. A surface mount device, 1N4148WS, is available in a plastic SOD package.

SPECIFICATIONS

VRRM = 100 V — maximum repetitive reverse voltage

IO = 200 mA — average rectified forward current

IF = 300 mA — maximum direct forward current

VF = 1.0 V at 10 mA.[7]

IFSM = 1.0 A (pulse width = 1 s), 4.0 A (pulse width = 1 µs) — non-repetitive peak forward surge current

PD = 500 mW — power dissipation

TRR < 4 ns — reverse-recovery time

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555 TIMER IC

Pin

Name Purpose

1 GND Ground reference voltage, low level (0 V)

2 TRIGThe OUT pin goes high and a timing interval starts when this input falls below 1/2 of CTRL voltage (hence TRIG is typically 1/3 VCC, CTRL being 2/3 VCC by default, if CTRL is left open).

3 OUTThis output is driven to approximately 1.7 V below + VCC or GND.

4RESET

A timing interval may be reset by driving this input to GND, but the timing does not begin again until RESET rises above approximately 0.7 volts. Overrides TRIG which overrides THR.

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5 CTRLProvides "control" access to the internal voltage divider (by default, 2/3 VCC).

6 THRThe timing (OUT high) interval ends when the voltage at THR isgreater than that at CTRL (2/3 VCC if CTRL is open).

7 DISOpen collector output which may discharge a capacitor between intervals. In phase with output.

8 VCCPositive supply voltage, which is usually between 3 and 15 V depending on the variation.

Modes Of Operation

The 555 has three operating modes:

Monostable mode: In this mode, the 555 functions as a "one-shot" pulse generator. Applications include timers, missing pulse detection, bouncefree switches, touch switches, frequency divider, capacitance measurement, pulse-width modulation (PWM) and so on.

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Astable (free-running) mode: The 555 can operate as an oscillator. Uses include LED and lamp flashers, pulse generation, logic clocks, tone generation, security alarms,pulse position modulation and so on. The 555 can be used as a simple ADC, converting an analog value to a pulse length. E.g. selecting a thermistor as timing resistor allows the useof the 555 in a temperature sensor: the period of the output pulse is determined by the temperature. The use of a microprocessor based circuit can then convert the pulse period to temperature, linearize it and even provide calibration means.

Bistable mode or Schmitt trigger: The 555 can operate as a flip-flop, if the DIS pin is not connected and no capacitor is used. Uses include bounce-free latched switches.

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WORKING

The fire alarm circuit here is designed with the principle of working of an astablemultivibrator using IC 555. An astable multivibrator is a circuit which generates continuous pulses atthe output terminal for the designed frequency. The generated frequency produces sound when it isconnected to a loudspeaker.

In the above circuit the sensor used is a germanium diode 1N4148 which is reverse biased inthe circuit. The reverse resistance of the diode is very high and current cannot pass through thediode at room temperature.

In the astable multivibrator of our circuit, the reset pin is connected ground. At thiscondition the astable multivibrator cannot produce frequency. At room temperature transistor T1 onsince the base of the transistor T1 gets enough potential since the diode is not conducting and offering a high resistance.

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When temperature of the diode increases in case of fire, the junction of the diode breakdowns and start conducting. At about 70˚c its resistance drop to a value below 1KΩ. This stops T1 conducting sincebase of t1 is now connected directly to ground through diode D1 and ground connection to the pin 4of IC 555 is now removed and is now connected to the Vcc through R2. Now astable multivibrator is activated and starts generating frequency which produces the alarm sound

2010IC 555

The 8-pin 555 timer must be one of the most useful ICs ever made and it is used in many projects. With just a few external components itcan be used to build many circuits, not all of them involve timing!

A popular version is the NE555 and this is suitable in most cases where a '555 timer' is specified. The 556 is a dual version of the 555 housed in a 14-pin package, the two timers (A and B) share the samepower supply pins. The circuit diagrams on this page show a 555, butthey could all be adapted to use one half of a 556.

Low power versions of the 555 are made, such as theICM7555, but these should only be used when pecified (to increase battery life) because their maximum output current of about 20mA (with a 9Vsupply) is too low for many standard 555 circuits. TheICM7555 hasthe same pin arrangement as a standard555

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Inputs of 555

Trigger input:when <1/3Vs ('active low') this makes the output high (+Vs). It monitors the discharging of the timing capacitor in an astable circuit. It has a high input impedance >2M.

Threshold input:when >2/3Vs ('active high') this makes the output low (0V)*. It monitors the charging of the timing capacitor in astable and monostable circuits. It has a high i n p u t i m p e d a n c e > 1 0 M . * providing the trigger input is >1/3Vs, otherwise the trigger input will override the threshold input and hold the output high (+Vs).

Reset input:when less than about 0.7V ('active low') this makes the output low (0V), overridingother inputs. When not required it should be connected to +Vs. It has an input impedance of about1 0 k .

Control input:This can be used to adjust the threshold voltage which is set internally to be2/3Vs.Usually this function is not required and the control input is connected to 0V with a 0.01µF capacitor to eliminate electrical noise. It can be left unconnected if noise is not a problem.

Discharge pinIt is not an input, but it is listed here for convenience. It is connected to 0V when the timer output is low and is used to discharge the timingcapacitor in astable and monostable circuits.

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Output of 555

The output of a standard 555 or 556 can sink and source up to200mA. Thisis more than most ICs and it is sufficient to supply many output transducersdirectly, including LEDs (with a resistor in series),low current lamps, piezo transducers, loudspeakers (with a capacitor in series), relay coils (with diode protection) and some motors (with diode protection). The output voltage does not quite reach 0V and +Vs, especially if a large current is flowing.

To switch larger currents you can connect a transistor.

The ability to both sink and source current means that two devices can be connected to the output so that one is on when the output is low and the other is on when the output is high. The top diagram shows two LEDs connected in this way. This arrangement is used in the Level Crossing project to make the red LEDs flash alternately.

Loudspeakers

A loudspeaker (minimum resistance 64) may be connected to the output of a 555 or 556 astable circuit but a capacitor (about 100µF)must be connected in series. The output is equivalent to a steady DC of about ½Vs combined with a square wave AC (audio) signal. The capacitor blocks the DC, but allows the AC to pass as explained in capacitor coupling.

Piezo transducers may be connected directly to the output and do not require a capacitor in series.

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COMPONENTS REQUIRED

RESISTORS (+5% CARBON,1/4W)

R1 - 1KΩ 1NOS R2 - 4.7KΩ 1NOSR3 - 10KΩ 1NOS R4 - 47KΩ 1NOSVR1 - 100KΩ 1NOS(PRESET) H

CAPACITORS

C1,2 - 0.01μF 2NOSC3 - 100 μF/ 1NOS 16V

MISC IC1 - 1C555 1NOS T1 - BC548 1NOSLS - 2 ½” 8E SPK/. 1NOSD1 - 1N4148 GER DIODE 1NOS

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METHODOLOGY

Design your circuit board. Use PCB Wizard software to draw your

circuit board. You can also use a perforated board that has pre-drilledholes in it to help you see how your circuit board's components wouldbe placed and work in reality.

Buy a plain board that is coated with a fine layer of copper on one

side from a retailer.

Scrub the board with a scouring pad and water to make sure the

copper is clean. Let the board dry.

Print your circuit board's design onto the dull side of a sheet of blue

transfer paper. Make sure the design is oriented correctly for transfer.

Place the blue transfer paper on the board with the circuit board's

printed design against the copper.

Lay a sheet of ordinary white paper over the blue paper. Following

the transfer paper's instructions, iron over the white and blue paper totransfer the design onto the copper board. Iron every design detailthat appears near an edge or corner of the board with the tip of theiron.

Let the board and blue paper cool. Peel the blue paper slowly away

from the board to see the transferred design.

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Examine the transfer paper to check for any black toner from the

printed design that failed to transfer to the copper board. Make surethe board's design is oriented correctly.

Replace any missing toner on the board with ink from a black

permanent marker. Allow the ink to dry for a few hours.

Remove exposed parts of the copper from the board using ferric

chloride in a process called etching.

Wash all the etching equipment and the circuit board thoroughly with

plenty of running water.

Drill 0.03 inch (0.8 mm) lead component holes into your circuit board

with high-speed steel or carbide drill bits. Wear safety goggles and aprotective mask to protect your eyes and lungs while you drill.

Scrub the board clean with a scouring pad and running water. Add

your board's electrical components and solder them into place.

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PCB LAYOUT

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TROUBLESHOOTING

After building up the entire project we came to know that our project was not working, this condition was havoc for us.

After Troubleshooting the circuit we came across following faults:-

Two of the IC pins were short circuited.

This problem was solved by desoldering those pins, & again soldering themback to the PCB with care.

A wrong diode was installed instead of 1n4148 germanium diode.

This time we replaced that diode with a 1n4148 germanium diode and observed whether the circuit is working or not.

Transistor was faulty.

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After checking the hfe of the transistor we came to a conclusion that we have to change the transistor as it was damage due to use of improper

soldering techniques.ADVANTAGES

1. Early WarningMany fires occur at night or in a room or section that no one may be in at the time. The audible alert from the fire alarm can wake individuals up who may otherwise sleep while inhaling smoke. Thealert can also provide an early signal during the day to individuals who, if not for the alarm, would not have the time needed to escape the home or building before the fire spreads out of control.

2. Flexibility to place them in specific rooms and areas of your choice.

3. Low CostA fire system that is remotely monitored on a continuous basis is normally part of an agreement with an alarm company that also includes burglar alarms.

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DISADVANTAGES

1. Susceptible to nuisance alarms if placed too close to cooking.

2. May be slow to respond slow smoldering fires.

3. None what so ever!!! They are there to save lives- whatever theydo. Although they could be a nuisance if they do cause falseactivations by themselves.

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APPLICATION

1. Fire alarms can be used in any place like parks, theaters, HOTELS, restaurants, boats, ships, etc.

2. Fire alarms can be also used as temperature sensors in some applications, when the temperature goes up abruptly it can inform.

3. Fire alarm can be used in our home for safety purpose and it is a very good precautionary measure.

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CONCLUSION

A fire alarm is a device that detects the presence of fire and atmospheric changes relating tosmoke. In some cases, a firm alarm is a part of a complete security system, in addition to aburglary protection system. The fire alarm operates to alert people to evacuate a location inwhich a fire or smoke accumulation is present.

When functioning properly, a fire alarm will sound to notify people of an immediate fireemergency. Fire alarms can be found in homes, schools, churches and businesses, andfunction as the catalyst to saving lives. For most fire alarms, when sounded, a beep, bell orhorn noise is made. This distinct sound exists to allow the notification to be heard The fire alarm constructed by this project work is reliable at low cost.

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BIBLIOGRAPHY

CIRCUITS AND NETWORKS –A SUDHAKAR, SHYAMMOHAN.PILLAI

OP-AMPS AND LINEAR INTEGRATED CIRCUITS – RAMAKANT A.GAYAKWAD

www.nfpa.org

en.wikipedia.org

www.ask.com

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