Infrared Flame Sensor Switch

the infrared detector switch is a very sensitive circuit that can be use to detect the presence of a flame, match, or a heat source, such as an iron or soldering iron. up to 3 feet away an then activate a relay. the heart of the infrared flame detector circuit is two tiny thermistor, as shown in figure 1.
a thermistor is a temperature sensitive resistor which changes its resistance as the temperature varies. glass bead or bulb thermistor are recommended for tis project.

schematic diagram for Infrared Flame sensor Switch

part list :

1. T1, T2 25K to 50K ohm thermistor

2. R1 33K ohm

3. R2 50K potensio

4. R3 1K ohm

5. R4 47 ohm

6. D1 1N4002

7. Q1 2n2222 

8. RY-1 SPDT 6 volt relay

9. U1 LM741

10. B1 9V battery

11. S1 SPDT toggle switch