How IR Flame Sensor Module Works

In general, infrared radiation is the transfer of energy from one place to another through electromagnetic waves. Every object emits and absorbs infrared radiation. If an object is hotter, then it radiates more energy. When this emitted energy hits an object, some of the energy will be absorbed by the object while the remaining part will get reflected back. When the object absorbs this energy, its temperature increases. So what does a flame sensor do is, the photodiode present in the sensor senses the IR waves emitted by the burning object, and then changes its resistance accordingly, which in turn changes the output of the sensor. There are different types of flame sensors, some of them are Ultraviolet flame sensors, Near IR array flame sensors, IR3 flame detection sensors. The application of flame sensors is in a number of hazardous environments, such as industrial gas turbines, domestic heating systems, hydrogen stations, etc. The flame sensor which we are going to discuss senses the flames using the IR waves. To detect the IR waves produced by the flames, we will be using a photodiode.

Pinout of the Flame sensor:
This IR flame sensor consists of a photodiode, resistor SMD package of value 10K-2N0, capacitor SMD package of value 100nF – 2No, resistor SMD package of value 1K-2N0, potentiometer of value 10K- 1No, SMD led-2No.

Circuit Diagram of the Flame Sensor Module:
The 8th pin of the LM393 is connected to the Vcc(5V) of the supply, and the 4th pin of the LM393 IC is connected to the GND. A 100nF capacitor (SMD package) is connected between the Vcc and the GND. The LED’s (used as a power indicator) anode terminal is connected to the resistor of 1K and the diode’s cathode is connected to the ground. The other end of the resistor is connected to the Vcc(5V). The photodiode’s cathode terminal is connected to a resistor of 10K and its anode terminal is connected to the GND. The other end of the resistor is connected to the Vcc(5V). An extra connection is taken from the connection point of photodiode and resistor and connected to the non-inverting terminal of the LM393 IC. A capacitor of 100 nF is connected between the non-inverting terminal and the GND. A potentiometer is connected in such a way that one of its fixed ends is connected to the Vcc and the other end is connected to the GND. Its variable end is connected to the inverting terminal of the LM393 IC. The LED’s ( used for indicating the Output) anode is connected to the Vcc and its cathode is connected to a resistor of 1K Ohm. The other end of the resistor is connected to the output pin(pin 1) of the LM393. A resistor of value 10K is connected between the Vcc and output pin of the LM393 IC.