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My Project Proposal

This document describes a file alarm circuit project proposal submitted to Sir Sohail Muzammil. The circuit uses a thermistor, LM358 IC, battery, amplifier, and buzzer. It functions by detecting increases in temperature via a thermistor, which decreases resistance as temperature rises. This triggers the LM358 op-amp to activate the buzzer, alerting users to a potential fire. Diagrams and explanations of the circuit design, components, working principle, and uses for fire detection are provided. References on simple fire alarm circuits using the LM358 IC are also listed.

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52 views5 pages

My Project Proposal

This document describes a file alarm circuit project proposal submitted to Sir Sohail Muzammil. The circuit uses a thermistor, LM358 IC, battery, amplifier, and buzzer. It functions by detecting increases in temperature via a thermistor, which decreases resistance as temperature rises. This triggers the LM358 op-amp to activate the buzzer, alerting users to a potential fire. Diagrams and explanations of the circuit design, components, working principle, and uses for fire detection are provided. References on simple fire alarm circuits using the LM358 IC are also listed.

Uploaded by

ziaulhaq
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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COMSATS INSTTITUTE OF INFORMATION

TECHNOLOGY

Project proposal EPE 2A

Topic:File Alarm Circuit

Submitted To:Sir Sohail Muzammil

 Group Members

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01
Circuit Materials

 Thermistor 10K
 Ic LM 358
 Battery 9 volt
 Amplifier
 Buzzer
 Potentiometer 10K

02
Basic Theory
Fire Alarm Circuit is a simple circuit that detects the fire and activates the Siren Sound or
Buzzer. Fire Alarm Circuits are very important devices to detect fire in the right time and
prevent any damage to people or property.
Fire Alarm Circuits and Smoke Sensors are a part of the security systems which help in detecting
or preventing damage. Installing Fire Alarm Systems and Smoke Sensors in commercial
buildings like offices, movie theatres, shopping malls and other public places is compulsory.

There are many expensive and sophisticated Fire Alarm Circuit in the form of stand-alone
devices, but we have designed five very simple Fire Alarm Circuits using common components
like Thermistor, LM358, Germanium Diode, LM341 and NE555.

We will see all these circuit, their circuit diagrams, components required for each circuit and the
working of the individual circuit in the following sections.
03
Project Circuit Diagram
04
Design Working

The design of the Fire Alarm Circuit with Siren Sound is very simple. First, connect the 10 KΩ
Potentiometer to the inverting terminal of the LM358 Op – Amp. One end of the POT is
connected to +5V, other end is connected to GND and the wiper terminal is connected to Pin 2 of
Op – Amp.

We will now make a potential divider using 10 K Thermistor and 10 KΩ Resistor. The output of
this potential divider i.e. the junction point is connected to the non – inverting input of the
LM358 Operational Amplifier.

We have chosen a small, 5V buzzer in this project to make the alarm or siren sound. So, connect
the output of the LM358 Op – amp to the 5V Buzzer directly.

Pins 8 and 4 of the LM358 IC i.e. V+ and GND are connected to +5V and GND respectively.

05
Working Principle
We will now see the working of the simple Fire Alarm Circuit. First thing to know is that the
main component in detecting the fire is the 10 K Thermistor. As we mentioned in the component
description, the 10 K Thermistor used here is a NTC type Thermistor. If the temperature
increases, the resistance of the Thermistor decreases.

In case of fire, the temperature increases. This increase in temperature will reduce the resistance
of the 10 K Thermistor. As the resistance decreases, the output of the voltage divider will
increase. Since the output of the voltage divider is given to the non – inverting input of the
LM358 Op – Amp, its value will become more than that of the inverting input. As a result, the
output of the Op – Amp becomes high and it activates the buzzer.
06
Uses
Fire Alarm using Thermistor. ... The key component of the circuit is Thermistor, which has
been used as fire detector or fire sensor. Thermistor is temperature sensitive resistor, whose
resistance changes according to the temperature, its resistance decreases with the increase in
temperature and vice versa.

07
References
https://www.electronicshub.org/simple-fire-alarm-circuit/

https://www.google.com.pk/search?
q=uses+of+ic+lm358+fire+alarm&rlz=1C1CHBD_enPK768PK768&oq=uses+
of+ic+lm358+fire+alarm&aqs=chrome..69i57j0.26669j0j7&sourceid=chrome
&ie=UTF-8

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