Description
The 12V Flame Detection & Relay Control Module is a robust, all-in-one fire detection and response system designed for industrial, automotive, marine, and commercial applications where a 12V power supply is standard. Unlike 5V versions that rely on USB or microcontroller power, this module operates directly from 12V battery systems, vehicle electrical systems, marine power, or industrial 12V control panels — making it ideal for use in trucks, boats, RVs, generator rooms, and off-grid installations.
The module integrates an infrared-sensitive flame sensor with a powerful 12V relay output on a single compact board. When a flame is detected, the relay automatically activates, allowing you to directly control 12V alarms, strobe lights, exhaust fans, fuel shut-off solenoids, water pumps, or any other 12V DC load. The relay can also switch AC loads (up to 250V AC / 10A) using an external power source, providing maximum flexibility.
The sensor detects flames within the 760nm to 1100nm infrared wavelength range — the characteristic spectral signature of hydrocarbon-based flames (gas, oil, candles, wood, coal). It can reliably detect a lighter flame from up to 80cm (31 inches) away, with larger flames detectable at greater distances. The detection angle is approximately 60 degrees, providing a useful field of view for monitoring engine compartments, fuel storage areas, kitchens, or industrial equipment.
Key features include an onboard LM393 comparator with a blue potentiometer for adjustable sensitivity, allowing you to set the exact flame intensity threshold that triggers the relay. The relay provides SPDT (Single Pole Double Throw) contacts rated for 10A at 250V AC or 30V DC, making it capable of switching most common loads directly.
This module is ideal for fire alarm systems, vehicle fire suppression, marine engine room monitoring, boiler flame verification, industrial safety systems, and any 12V-powered application requiring automatic response to flame presence. It operates as a standalone device — no microcontroller or programming required.
Features
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Designed for 12V DC operation (vehicles, boats, industrial panels)
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Integrated flame sensor and relay on a single PCB
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Detects flame wavelengths: 760nm – 1100nm (infrared range)
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Detection distance: up to 80cm for lighter flame (larger flames detectable further)
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Detection angle: approximately 60 degrees
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Adjustable sensitivity via onboard blue potentiometer
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Onboard LM393 comparator for reliable threshold detection
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SPDT relay contacts: NO, NC, COM (10A/250V AC or 30V DC)
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LED indicator shows relay activation status
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Standalone operation — no microcontroller needed
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Screw terminal blocks for secure wiring
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Suitable for automotive, marine, and industrial environments
Technical Parameters
Usage Guide
1. Module Overview
The board has two main sections:
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Flame Sensor Section: Contains the IR phototransistor, LM393 comparator, and blue potentiometer for sensitivity adjustment.
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Relay Section: Contains the 12V relay, indicator LED, and three screw terminals (COM, NO, NC).
2. Wiring Instructions (12V DC Power)
For 12V DC Alarm Operation (load ON when flame detected):
12V Battery (+) ──→ COM (Relay)
Alarm (+) ──→ NO (Relay)
Alarm (-) ──→ Battery (-) / GND
Module VCC ──→ Battery (+)
Module GND ──→ Battery (-)
3. Sensitivity Adjustment
The blue potentiometer adjusts the flame intensity threshold:
Safety Tip: When testing with a lighter, keep it at least 30cm from the sensor. Do not hold the flame directly against the sensor — high heat will permanently damage the IR phototransistor.
4. Using Without a Microcontroller (Standalone Mode — Recommended)
The module works entirely on its own with just a 12V power supply:
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Connect 12V and GND to a vehicle battery, marine battery, 12V power supply, or 12V adapter
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Connect your 12V alarm, siren, strobe light, or other load to the relay terminals (COM and NO)
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Adjust sensitivity with the potentiometer
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When a flame is detected, the relay clicks ON and the LED lights
No programming required — truly plug-and-play!
5. Using With a Microcontroller (Optional)
The module also provides a digital output (labeled DO or OUT) that changes state when a flame is detected. This can be connected to a microcontroller for additional logic (e.g., sending a text message, logging events, or coordinating multiple sensors).
Arduino Connection (5V/3.3V microcontroller with level shifting):
Warning: The digital output is 12V. Do NOT connect directly to a 5V or 3.3V microcontroller pin without a voltage divider or level shifter.
6. Common 12V Applications
7. Using with AC Loads
The relay can also switch 110V/220V AC loads (e.g., home alarm siren, building exhaust fan) using an external AC source:
AC Live (110V/220V) ──→ COM (Relay)
AC Load Live ──→ NO (Relay)
AC Neutral ──→ Load Neutral (direct)
⚠️ The module itself still requires 12V DC power. The relay contacts are isolated — AC and DC sides do not mix.
8. Important Notes
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Keep the sensor at a safe distance from the flame — high temperatures can permanently damage the IR phototransistor. Minimum safe testing distance: 30-40cm for a lighter flame.
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The sensor also responds to sunlight and other infrared sources (heaters, incandescent bulbs, hot surfaces). For fire detection, position the sensor away from direct sunlight or other IR sources.
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Vehicle/engine compartments — The module operates on 12V nominal (10V–14V range). It will tolerate typical automotive voltage variations (including charging voltage up to ~14.5V). For higher spikes (load dump), we recommend adding a 16V TVS diode across VCC/GND for protection.
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Marine environments — The PCB is not waterproof. For marine use, mount inside a waterproof enclosure.
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For critical fire safety applications, use multiple modules for redundancy and combine with other detection methods (smoke, heat, gas sensors).
Q: What is the difference between the 12V and 5V versions of this module?
Choose the 12V version if your power source is a vehicle battery, marine system, or industrial 12V control panel.
Q: What types of flames can this module detect?
The module detects flames from hydrocarbon-based fuels — including gasoline, diesel, propane, natural gas, butane (lighters), candles, wood, coal, and oil fires. It detects the infrared radiation (760nm–1100nm wavelength) emitted by these flames.
Q: How far can it detect a flame?
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Lighter flame: Approximately 80cm (31 inches)
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Candle flame: Approximately 50-70cm (20-28 inches)
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Larger fire: Several meters — the larger the flame, the farther the detection distance
The exact distance depends on flame intensity, ambient light conditions, and sensitivity setting.
Q: Does it detect sunlight or artificial light?
Yes, the sensor will respond to strong infrared sources including:
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Direct sunlight (especially midday)
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Incandescent light bulbs (halogen, standard bulbs)
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Infrared heaters and heat lamps
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Hot engine components (exhaust manifolds, turbochargers)
For this reason, position the sensor carefully. In engine compartments, aim the sensor away from hot exhaust components. In outdoor applications, shield the sensor from direct sunlight.
Q: Can I adjust the sensitivity? How?
Yes. The onboard blue potentiometer adjusts the detection threshold:
Adjust while testing with a flame (at a safe distance) until the relay activates reliably at your desired distance and ignores false sources.
Q: Does this module need a microcontroller to work?
No. The module works in standalone mode with just a 12V power supply. When a flame is detected, the relay automatically activates — you can directly connect a 12V alarm, siren, solenoid, or other load to the relay terminals. This makes it perfect for vehicle fire suppression and other 12V systems without programming.
Q: What loads can I control with the relay?
The relay is rated for 10A at 250V AC or 10A at 30V DC — sufficient for most common 12V loads:
For inductive loads (solenoids, motors, pumps), we recommend derating to ≤5A or adding a flyback diode across the load.
Q: Can I use this module in a vehicle? Is it protected against voltage spikes?
Yes, the module is designed for 12V automotive systems (10V–14V range). However, vehicles can experience voltage spikes during load dump (e.g., disconnecting a battery while alternator is charging). For maximum reliability:
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We recommend adding a 16V or 18V TVS diode (e.g., 1.5KE16A) across VCC and GND
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Alternatively, use a 12V automotive-grade power filter upstream of the module
The module alone will work for most passenger vehicles, but heavy trucks and industrial equipment may require additional protection.
Q: Can I use this module in a marine environment (boat engine compartment)?
Yes, with precautions:
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The PCB is not waterproof — mount inside a waterproof enclosure (IP65 or better)
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Use marine-grade connectors and heat-shrink tubing on all connections
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Apply conformal coating to the PCB for moisture resistance
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Avoid mounting directly above bilge water or in areas prone to condensation
Q: Why is my module triggering randomly or too easily?
Possible causes:
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Sunlight or IR sources in the detection area — reposition the sensor or shield it
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Hot engine components — aim sensor away from exhaust manifolds, turbochargers
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Sensitivity too high — turn potentiometer clockwise to reduce sensitivity
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Electrical noise — ensure stable 12V power (add a capacitor: 1000µF / 25V across VCC/GND)
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Reflective surfaces — flames reflecting off shiny surfaces can cause false triggers
Q: Why isn't my module detecting flames at all?
Troubleshooting steps:
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Check power — measure 12V across VCC and GND
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Check sensitivity — turn potentiometer counter-clockwise for higher sensitivity
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Check flame distance — move flame closer (but keep safe distance of ~30cm)
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Check ambient IR — bright sunlight may saturate sensor; test in darker conditions
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Check relay indicator LED — if LED lights but load doesn’t work, check load wiring
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Verify the sensor window is clean (no dust, grease, or smoke residue)
Q: Can I use this module with a 24V vehicle system (truck, bus, heavy equipment)?
No, not directly. The module is designed for 12V nominal (10V–14V). For 24V systems (e.g., trucks, buses, heavy equipment), you have two options:
Do NOT connect the module directly to 24V — it will be permanently damaged.
Q: Can I use multiple flame detection modules together?
Yes. For multi-point coverage (e.g., engine compartment + fuel storage area):
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Connect each module to the same 12V power supply (ensure supply can handle total current)
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Wire the relay outputs of multiple modules in parallel to trigger a single alarm
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For individual alerts, connect each module to its own alarm or to a PLC/controller
Q: Is this module suitable for professional/commercial fire suppression systems?
This module is suitable for non-critical and supplementary fire detection applications such as:
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Vehicle fire pre-alert systems (race cars, off-road vehicles)
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Marine engine room monitoring (alarm only, not suppression release)
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Generator and pump house fire detection
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Industrial equipment monitoring (conveyors, hydraulic units)
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Agricultural machinery fire warning
For certified life safety or insurance-mandated fire suppression systems, you must use professional UL/FM/EN listed fire detection and control equipment. This module does not carry such certifications.
Q: Can I connect this directly to a fire extinguisher release solenoid?
Yes, with important safety considerations:
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The relay can switch a 12V solenoid valve for releasing an extinguisher
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We strongly recommend:
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Using a manual override (emergency pull station)
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Adding a time delay circuit (if using with microcontroller)
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Installing a pressure switch to prevent release if already discharged
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Testing the system thoroughly before relying on it
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For life safety applications, use a certified fire suppression control panel instead
Q: What happens if 12V power is lost?
The module requires 12V power to operate. If power is lost, flame detection and relay control will not function. For critical applications, we recommend:
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Connecting to a dedicated battery (not shared with starting battery)
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Using a battery-backed power supply (UPS for 12V systems)
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For engine compartments, connect directly to the house battery rather than the starting battery
Q: How do I mount the module?
The PCB has two mounting holes (approximately 3mm diameter) for screw mounting. Recommendations:
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Use M3 nylon screws and standoffs to prevent short circuits
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Mount on a non-conductive surface (plastic, wood, or with insulating washers)
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For vehicle/marine use, mount inside a protective enclosure (plastic project box)
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Position the flame sensor pointing toward the area to be monitored
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Keep away from direct heat sources (exhaust pipes, turbochargers)
Q: What is the response time when a flame is detected?
The response time is typically under 1 second — fast enough for most fire alert and suppression applications. The exact response time depends on sensitivity setting, flame intensity, and distance.
Q: Can this module detect fire through smoke or glass?
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Through smoke: Partial — smoke can attenuate the infrared signal, reducing detection distance. For smoky fires (e.g., electrical fires), we recommend combining with a smoke detector.
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Through glass: Very poor — standard glass blocks most infrared radiation. Do not mount behind glass windows, panels, or enclosures.
Q: What is the lifespan of the relay?
The relay is rated for approximately 100,000 switching cycles at rated load. In a typical fire detection application where the relay activates only during actual fire events (rarely), the lifespan is essentially the lifetime of the module.
