High Sensitivity Fire Detector Circuit
Build a high-sensitivity fire detector circuit. Step-by-step DIY guide with components, working principle, and applications for home, office, or industrial safe...
LED buzzer fire detection
A high-sensitivity fire detector circuit is a very necessary DIY project towards increasing the safety in homes, offices, and industrial premises. It identifies fire or an abrupt increase in temperature by use of a flame sensor or an IR sensor and sends an alarm to be responded to.
High-sensitivity flame alarm project
This circuit is very sensitive and can detect the occurrence of small flames or fire breaking out, and therefore, early intervention can be done. It normally employs a flame sensor, a transistor, or an operational amplifier to amplify the signal and a buzzer or LED to provide an alert. This manual describes the parts, operating principle, circuit diagram, and construction of a high-sensitivity, low-cost, and high-reliability fire detector.
Fire Detector Circuit Guide
Key Features and Advantages
- Detects small and large flames quickly
- High sensitivity and fast response
- Can be used indoors or outdoors
- Visual (LED) and audible (buzzer) alert
- Compact and low-cost DIY solution
Components Required for Fire Detector Circuit
- Flame sensor module or IR sensor (3–5V)
- Transistor (e.g., BC547) or op-amp (e.g., LM358)
- Resistors for biasing and current limiting
- Capacitors for filtering and stability
- Buzzer or piezo speaker for alarm
- LED indicator for visual alert
- Power supply (5V–12V DC)
- Wires, breadboard, or PCB for assembly
Working Principle
Fire Detection Sensor
The flame sensor detects infrared radiation emitted by fire. Changes in sensor output voltage indicate flame presence.
Signal Amplification
A transistor or op-amp amplifies the weak sensor signal, ensuring the buzzer or LED receives enough current to activate.
Alarm Activation
The amplified signal triggers the buzzer and LED simultaneously, providing immediate alert.
Power Supply and Protection
Uses regulated DC supply with diodes or resistors for protection against voltage spikes.
Circuit Diagram of High Sensitivity Fire Detector
- Connect flame sensor output to the base of a transistor or input of op-amp.
- Bias the transistor using resistors for sensitivity control.
- Connect buzzer and LED in parallel to the amplified output.
- Power the circuit with 5V–12V regulated DC.
- Add filtering capacitors for sensor stability.
- Adjust sensitivity using a potentiometer if available.
Step-by-Step Construction Guide
- Mount the flame sensor on a PCB or breadboard.
- Connect transistor or op-amp for signal amplification.
- Add LED and buzzer for alarm output.
- Connect resistors and capacitors as per circuit diagram.
- Power the circuit with regulated DC supply.
- Test detection using a small flame (candle or lighter).
- Adjust sensitivity to avoid false alarms.
Applications of Fire Detector Circuit
- Home and office fire alarm systems
- Laboratory safety
- Industrial flame detection
- DIY electronics safety projects
- Early workshop fire detection systems
Safety Precautions
- Keep flammable objects away during testing.
- Use proper insulation and wiring.
- Avoid overvoltage to sensor or alarm components.
- Test in controlled conditions before final installation.
Troubleshooting Common Issues
False Alarms
Adjust sensor sensitivity and ensure no sunlight or IR source interference.
Alarm Not Triggering
Check sensor alignment, wiring, and transistor/op-amp condition.
Sensor Sensitivity Adjustment
Use a potentiometer or change bias resistor values for fine-tuning.
