Smoke Detector Alarm Circuit
A Smoke Detector is a smoke sensing device that indicates fire. Smoke
Detectors are very common in homes, offices, schools and industries.
Smoke Detectors are very useful devices as the damage caused by fire
accidents is catastrophic.
Now a days, smoke detectors and smoke alarms are very cheap as its
usage is increasing and cost of manufacturing is decreasing. In this
project, we are implementing a simple Smoke Detector Circuit using
simple hardware.
We used a Gas/Smoke sensor for detecting smoke. The article is divided into information about Smoke sensor, circuit diagram and working.
Optical smoke detectors consists of a light source like LED and a light detector like photocell.
The photocell conducts as long as the light falls on it. When there is smoke, the light from the source is interrupted and the photocell doesn’t conduct.
Ionization smoke detectors consists of two electrodes and an ionization chamber filled with ions. When there is no smoke, the ions move freely and the electrodes conduct normally.
In the presence of smoke, the chamber is filled with smoke and interrupts the movement of ions. The electrodes do not conduct anymore. Depending on the type of sensor and manufacturer, the conductivity conditions may change but the idea remains the same.
Based on the output of the smoke detector, an alarm system can be implemented.
The sensor used in this project is MQ-2 Gas/Smoke sensor. It is sensitive to LPG, Hydrogen, Smoke, Methane, Propane, Alcohol, Butane and other industrial combustible gases.
It has two electrodes made of Aluminum Oxide (Al2O3) and a heating element made of Tin dioxide (SnO¬2) which acts as the main sensing layer.
We used a Gas/Smoke sensor for detecting smoke. The article is divided into information about Smoke sensor, circuit diagram and working.
A Brief Introduction to Smoke Sensor
There are two types of smoke detectors. Optical or Photoelectric smoke detectors and Ionization smoke detectors.Optical smoke detectors consists of a light source like LED and a light detector like photocell.
The photocell conducts as long as the light falls on it. When there is smoke, the light from the source is interrupted and the photocell doesn’t conduct.
Ionization smoke detectors consists of two electrodes and an ionization chamber filled with ions. When there is no smoke, the ions move freely and the electrodes conduct normally.
In the presence of smoke, the chamber is filled with smoke and interrupts the movement of ions. The electrodes do not conduct anymore. Depending on the type of sensor and manufacturer, the conductivity conditions may change but the idea remains the same.
Based on the output of the smoke detector, an alarm system can be implemented.
The sensor used in this project is MQ-2 Gas/Smoke sensor. It is sensitive to LPG, Hydrogen, Smoke, Methane, Propane, Alcohol, Butane and other industrial combustible gases.
It has two electrodes made of Aluminum Oxide (Al2O3) and a heating element made of Tin dioxide (SnO¬2) which acts as the main sensing layer.
Circuit Diagram
Components Required
- MQ-2 Sensor
- LM358
- 10KΩ
- 330Ω
- LED
- 0.1µF
- 10KΩ POT