Flame Sensor
What is a Flame Sensor?
A flame sensor module detects infrared light commonly emitted by fire. Low-cost Arduino flame modules are useful for classroom fire-detection demos, candle detection, robot safety experiments, and alarm prototypes.
A flame sensor is not a certified life-safety smoke alarm. It needs line of sight, can be affected by sunlight and IR sources, and should only be used for educational or supervised automation projects unless paired with proper safety-rated equipment.
Key Features
IR Flame Detection
Detects strong infrared radiation in the flame-sensitive wavelength range.
Analog Output
AO can estimate relative flame intensity or distance under controlled conditions.
Digital Alert Output
DO provides a simple threshold trigger for buzzers, relays, and alarm logic.
Adjustable Threshold
Comparator modules include a potentiometer for trigger sensitivity.
Robot Safety Use
Works in supervised fire-fighting robot and obstacle-demo projects.
Beginner Friendly
Connects with VCC, GND, and one output pin for quick Arduino experiments.
Pin Configuration
VCC
Power input. Most flame sensor modules support 3.3V to 5V operation.
GND
Ground reference shared with the controller.
AO
Analog sensor voltage that changes with detected IR intensity.
DO
Digital comparator output based on the onboard threshold setting.
How It Works
The Science Behind It
The sensing diode responds strongly to infrared radiation. Flames emit flickering IR energy, so the sensor output changes when it faces a candle or fire source.
The module can expose the raw analog sensor signal and a comparator-based digital trigger. The digital output is convenient, but analog readings are better for tuning and diagnostics.
Detection Logic:
Low IR background = safe baseline
Strong flame IR = analog value changes
Comparator threshold crossed = digital alert
Treat this as an educational detector. Do not replace certified smoke, heat, or fire alarm systems with hobby modules.
Wiring Tips & Best Practices
Avoid Sunlight
Direct sunlight and hot lamps can trigger the sensor because they contain infrared energy.
Keep Line of Sight
The sensor must face the flame. It cannot detect fire hidden behind objects or walls.
Test Real Distance
Sensitivity changes quickly with distance and flame size, so tune the module in your exact setup.
Respect Fire Safety
Use small supervised test flames and keep extinguishing equipment nearby during experiments.
Confirm with Timing
Require the signal to stay active for several readings before triggering an alarm.
Use Redundant Sensors
For serious monitoring, pair flame detection with smoke, temperature, or certified safety devices.