Flame Sensor
Flame Sensor
  • Operating Voltage: 3.3V-5V
  • 3 pins: VCC, GND and SIGNAL
  • SIGNAL pin gives a digital output
  • Detection angle: 60° approximately
  • Adjustable sensitivity
  • Digital Output
  • Operating Voltage: 3.3V-5V
  • Fixed bolt holes for easy mounting (Small size: 3.2cm x 1.4cm)


This sensor as its name suggests detects flame. To be clearer it detects heat around itself. This sensor module comes with three pins: VCC, GND and SIG. It works well with 5V and gives a digital output. This sensor module has an onboard comparator which compares the analog voltage, from the sensor, with a threshold voltage that can be set via potentiometer (also available on board). This potentiometer helps to adjust the range of its detection.

This sensor module can be used to detect flame/fire in the range of 760nm to 1100 nm wavelength of light. Small flames can be detected at a distance of roughly 80cm, while bigger flames can be detected from farther distances. It can be used to directly drive other modules as it has digital output of 15mA. The sensor must maintain some distance from the flame, so as not to damage it.

A small project with Atmega 16 microcontroller:

The module requires VCC and GND supply and it gives its output through SIG pin that I have connected to PC7 of AtMega 16 IC. On detecting the flame it provides a 0 level signal (0V), while being idle it gives a high level signal (5V). I have connected the LCD pins to PORTB; this LCD is working on 4 bit data/command mode.

Apart from LCD display, I have also connected a buzzer for flame detection indication. It is connected to PC6. So, till the time IC is getting a low signal on PC7 it will play on the buzzer and display “FIRE DETECTED” content on LCD. As soon as this signal turns ON (5V), it will stop displaying the message and switch off the buzzer.

Circuit Diagram




void main()
int i=0;
DDRC&=~(1<<7); //input from flame sensor
DDRC|=(1<<6); //output for buzzer

LCDdisplay("Fire detected");



Flame Sensor [Video link]


Possible Application Areas

  • fire alarms
  • fire fighting robots


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