IR Flame Sensor Module
Infrared flame detector for early fire-alert projects.
Wiring & code for
Flame Sensor practical reference
An IR-photodiode-based sensor tuned to detect the infrared signature of open flame, popular in DIY fire-alarm and safety projects. It uses an infrared photodiode sensitive to the specific wavelength range emitted by a flame (roughly 760-1100nm), producing both a digital threshold output and a proportional analog signal so a microcontroller can detect not just the presence of fire but roughly how close or intense it is — a common building block for fire-alert systems, candle-detection demos, and safety shutoffs.
Key specifications
- Sensor type: IR photodiode flame sensor with LM393 comparator driver board
- Operating voltage: 3.3V–5V DC
- Operating current: ~15 mA typical
- Detection wavelength: ~760-1100nm (the IR range associated with combustion flame)
- Detection angle: ~60° cone typical
- Detection range: ~20cm-100cm for a small open flame (like a candle or lighter), depending on flame size and sensitivity setting
- Digital output (DO): Goes LOW when flame IR is detected above the threshold set by the onboard potentiometer (HIGH otherwise, on most boards)
- Analog output (AO): Continuous voltage proportional to detected flame IR intensity
- Interface: 1 digital pin (threshold trigger) + 1 analog pin (intensity reading)
Pinout and connection notes
Because this sensor responds to IR wavelengths, direct sunlight or strong incandescent lighting can trigger false positives — test the sensitivity potentiometer setting in the actual deployment environment rather than assuming lab/indoor test conditions will match. This is a hobby-grade detection aid and should not be relied upon as a certified life-safety fire alarm.
- VCC: Power, 3.3–5V DC
- GND: Ground
- DO: Digital output — threshold-triggered flame detection
- AO: Analog output — proportional to detected flame intensity
Integration checklist
- Confirm the exact part number and breakout-board revision.
- Verify supply voltage, current demand, logic levels, and signal direction against the datasheet.
- Check controller pin assignments and bus address or interface mode against the example code.
- Power up with external loads disconnected, then test signals before full integration.
- If readings or communication fail, check power and ground first, then pin mapping, interface settings, and library initialization.
Troubleshooting and reproducibility
Record the board used, wiring, library/version, supply arrangement, and measured behavior. Use the selected board-specific wiring example as the source of truth. Never assume visually similar modules share identical voltage tolerance or pin order.