A Mini project presentation on LOW COST FIRE ALARM Vaagdevi College of Engineering,Warangal

Presented by: V.Ajay kumar(09641A0415) V.Srinivas(09641A0424) Under guidance of S.Durgaprasad(09641A0402) Mrs.Vijaya T.Jagadeeshwar(09641A0450) (Assoc.Prof)

INTRODUCTION:

These project is entitled low cost fire alarm. The main aim of the project is to provide best security from fire asserts at low cost. This project uses a thermistor which can be used as a sensor to create a heat detection alarm systems.

It can be used in industries to protect the goods , security at warehouses,etc,.

CIRCUIT DIAGRAM

CIRCUIT DESCRIPTION:

• The circuit consist s of 1.Thermistor103 2. Slider switch 3. LED 4.Buzzer 5.9V battery 6.Transistors(A2222 , BC547) 7.Resistors(560 ohm,220K,10K) 8. Variable resistor(10K) and 9. Relay circuit 10.Buzzer

• 9V batteries are commonly used in pocket transistor radios , carbon monoxide alarms , smoke dectectors and as backup power to the time in digital.

• Thermistor is a type of resistor whose resistance varies significantly with temperature , more so than in standard resistors.

• Thermistors are widely used as inrush current limiters , temperature sensors , self-resetting overcurrent protectors and self-regulating heating elements.

• Transistors used are BC547,A2222 which for amplification purpose.

• Relay is a electrically operated switch which can have two contacts NC,NO and have sliding arm moving between them.

• Piezo buzzer is an electronic device commonly used to produce sound based on inverse piezoelectric effect.

• LED is a semiconductor light source ,based on semiconductor device and diode will be ON when it is in forward biased and light glows.

• Slide switch works on the principle of connecting disconnected parts to each others.

CIRCUIT OPERATION:

•When we give the supply to the circuit by using slide switch.

•The current passes through 10K resistor and the base of transistor A2222 become high and collector point become zero , hence the relay will activate .

•In this project initial the 6V relay will be in on condition , when we apply heat to the thermistor , then thermistor resistance will decrease .

• The current flow from the thermistor to base of transistor BC547 and the collector will becomes low means zero , and at the same the base of the transistor A2222 will be zero.

• The collector will be high means relay will deactivate , when the relay is deactivated .

• The point NC is connected the buzzer which gives sound , means there is fire.

• The common point C of relay is connected to 9V Vcc , when relay is ON , the point C will connect to NO , when relay is OFF , point C connect to NC.

• Thermistor is a component which decrease it resistance when it sense heat ,when the resistance decrease the flow of current will increase.

ADVANTAGES:

• Low cost

• Less complex circuitry

• Portable

• Simple and efficient

• More efficient

DISADVANTAGES:

• Very high temperatures are not applicable

• Delay time

• Variable resistor should be set properly if transistor may damage

APPLICATIONS:

• Home security

• To protect valuable in go-downs

• Museums

• Theatres

• All electric departments

• Industries

CONCLUSION:

• The important of these is it gives sound from fire alarm when fire attacks to industries , warehouses , etc,.

• It is most efficient , simple and less complex circuit which can be designed as small equipment , which eases the portability.

• It can be used to provide security at warehouses where storage and protection of various types of goods is main concern and works home security too.

• These circuit uses the thermistor sensing property of the temperature by increasing the temperature resistance resistance will decrease.

ANY QUERIES