IR Flame Sensor Module
Infrared flame detector for early fire-alert projects.
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.
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
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | Power, 3.3–5V DC |
| 2 | GND | Ground |
| 3 | DO | Digital output — threshold-triggered flame detection |
| 4 | AO | Analog output — proportional to detected flame intensity |
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.
Variants
The basic IR flame sensor is fine for demo-level fire-alert projects and is the cheapest option. For fewer false positives from ambient heat/light sources, a UV flame sensor is more selective at a higher cost; pairing either with an MQ-2 smoke sensor gives more robust, multi-signal fire detection than relying on flame-light sensing alone.
| Variant | Temp range | Hum range | Accuracy | Protocol | Price |
|---|---|---|---|---|---|
| IR flame sensor (3-pin, digital + analog) | ~$1-3 | ||||
| UV flame sensor | ~$5-15 | ||||
| MQ-2 gas/smoke sensor | ~$1-3 |