Smoke Detector Alarm Using LM358

In this tutorial, I will be going to show you a simple smoke detector alarm without using any microcontroller. A smoke detector alarm is a smoke-detecting gadget that shows fire. Smoke alarms are exceptionally normal in homes, workplaces, schools, and industries. Smoke alarms are extremely helpful gadgets as the harm brought about by fire mishaps is disastrous. These days, smoke alarms and smoke cautions are modest as their use is expanding and the expense of assembling is diminishing. In this undertaking, we are executing a basic smoke detector alarm circuit utilizing basic equipment. We utilized a Gas/Smoke sensor for distinguishing smoke.

There are two kinds of smoke alarms i.e Photoelectric smoke alarms and Ionization smoke alarms.

Photoelectric smoke alarms comprise a light source like LED and a light detector like a photocell. The photocell leads as long as the light falls on it. When there is smoke, the light from the source is hindered and the photocell doesn’t conduct. 

Ionization smoke alarms comprise two cathodes and an ionization chamber loaded up with particles. When there is no smoke, the particles move openly and the electrodes conduct typically.

Within the sight of smoke, the chamber is loaded up with smoke and intrudes on the development of particles. The anodes don’t conduct any longer. Contingent upon the kind of sensor and maker, the conductivity conditions may change yet the thought continues as before. 

In view of the output of the smoke alarm, a caution framework can be executed. 

The sensor utilized in this project is the MQ-2 Gas/Smoke sensor. It is delicate to LPG, Hydrogen, Smoke, Methane, Propane, Alcohol, Butane, and other mechanical burnable gases. 

It has two anodes made of Aluminum Oxide (Al2O3) and a warming component made of Tin dioxide (SnO2) which goes about as the principal detecting layer.


Smoke Detector Alarm Using LM358

Circuit Diagram

smoke detector alarm

Components Required

  • MQ-2 Gas Sensor
  • LM358 IC
  • Resistor (10 KΩ, 330 Ω
  • LED
  • 0.1µF Ceramic Capacitor
  • 10 KΩ Potentiometer

PCB Design

For removing messy wiring and giving a clean look, I designed a PCB prototype for this project. It is also helpful for troubleshooting that runs great without any errors. To design this PCB board, I used EasyEDA as it is too easy to use. For ordering PCB for this, I personally prefer PCBWay.

Gerber file for Smoke Detector Alarm Using LM358.

PCB View

Smoke Detector Using LM358 2D View
2D View
Smoke Detector Using LM358 3D View
3D View

Order PCB From PCBWay

This project is sponsored by PCBs are required everywhere in the electronics industry. So it needs to be good enough and have to serve the purpose for which they are needed without costing exorbitant amounts. PCBway offers all your needs come true. PCBWay is one of the largest PCB (Printed Circuit Board) manufacturing companies in China. It offers PCB prototype, PCB Assembly, SMD Stencil, and Flexible PCB.

They ship to more than 170 countries worldwide and process more than 2100 PCB orders a day. It feels like PCBWay gives an excellent price and customer service factor in one single serving. I personally ordered PCBs from PCBWay for my projects for just 5 dollars. I’ve used other PCB manufacturers too, but PCBWay has been offering the most reliable and consistent that I have tried. What is also spectacular about PCBWay to me, as a maker and customer, is their service. From their friendly support staff to their intuitive, user-friendly website features, it all counts towards what makes PCBWay an ideal company and brand for any electronics hobbyist.

Standard quality for any product needs to be maintained using some parameters. PCBWay gives that opportunity through quality control in designing and manufacturing. At first, they ensure the accuracy, clarity, and validity of the PCB files that we sent to them.

Then all the boards will go through the most stringent tests other than the basic visual check. They adopt most of the testing and inspecting equipment used in the industry, such as Flying Probe Testers, X-Ray Inspection machines, and Automated Optical Inspection (AOI) Machines. They are having 50+ new engineers on a daily basis around the world using PCBs for their work, who trust their reliable quality. They produce high-quality pink, orange, grey, and even transparent solder mask. Moreover, according to people’s needs, they can also provide Black core PCB. Check it out for a High-Quality PCB solder mask. There are some pictures below of the new colours of solder musks.

Working Principle of Smoke Detector

Smoke detector alarm is outstanding gadgets as they are little, modest yet helpful. In this project, we actualized a simple smoke detector alarm circuit with customizable affectability.

We utilized a smoke sensor MQ-2 as the fundamental tangible gadget. The working of the smoke detector alarm circuit is simple and is clarified beneath.

LM358 IC goes about as a comparator in this circuit. The transforming terminal of the LM358 IC is associated with POT so the affectability of the circuit can be balanced.

The output of the LM358 IC is given to a LED as a marker although a buzzer can be utilized as an alert. The non-modifying terminal of LM358 IC is associated with the output of the smoke sensor.

At first, when the air is perfect, the conductivity between the terminals is less, as the resistance is in the order of 50 KΩ. The inverting terminal input of the comparator is higher than the non-inverting terminal input. The pointer LED is OFF.

In the case of a fire, when the sensor is loaded up with smoke, the sensor’s resistance falls to 5 KΩ, and the conductivity between the terminals increases.

This gives a higher contribution at the non-inverting terminal of the comparator than the inverting terminal and the output of the comparator is high. The disturbing LED is turned ON as a sign of the essence of smoke.

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