The Smoke Detector Circuit detects smoke in the environment using an MQ2 gas sensor, which is highly sensitive to gases like propane, methane, and butane. This makes it a reliable component for detecting potential fire hazards. When the sensor detects smoke, the circuit triggers an alarm that alerts the user through a Piezo Buzzer, producing a loud and immediate sound to ensure quick attention and enhance safety.
The circuit runs on four AA batteries, housed in a battery holder for portability and accessibility. An LED indicator provides a visual cue alongside the sound alarm, offering both auditory and visual warnings. Components like resistors and jumper wires control the current flow, ensuring the circuit operates efficiently and safely in various settings.
Building this circuit gives you valuable insights into gas detection systems and their importance in safety applications. It also helps you practice essential electronics skills like wiring and soldering. Reinforcing the connections with heat shrink and using proper soldering techniques increase the circuit’s durability, ensuring reliable performance over time. This project lets you explore how different components work together to create an effective alert system.
By completing this project, you will sharpen your soldering, wiring, and troubleshooting skills, while learning about power management with batteries. Overall, this practical, real-world electronics application combines detection, alerts, and safety features, providing a rewarding learning experience for anyone interested in electronics.
Components:
- MQ2 Gas Sensor
- Piezo Buzzer
- LED 5mm Red
- Battery Holder
- Battery AA
- Resistors
- Jumper Wires
- Heat Shrink
- Solder Iron
- Solder Lead
Connection:
The schematic diagram of the MQ2 gas sensor module shows how it detects changes in gas concentration and turns these into usable signals. The MQ2 sensor works by changing its internal resistance when exposed to gases like smoke, propane, or methane. This change in resistance changes the output voltage, which is part of a voltage divider with resistors. As the gas levels change, so does the voltage at the output.
This voltage is sent to the LM393D comparator, which plays a key role in the detection process. The comparator compares the sensor’s output with a preset threshold (set by the potentiometer). If the gas concentration is higher than this threshold, the comparator’s output goes HIGH. This activates the digital output (D_OUT) pin and lights up the Trigger LED, signaling that dangerous gas levels have been detected.
The module also has an analog output (A_OUT) that shows the real-time gas concentration. This is useful if you want to measure the exact gas levels instead of just knowing if they crossed a certain limit. The LED indicators in the circuit help by showing when the power is on and when gas is detected. These features make the MQ2 module a useful tool for gas detection, providing both sound and light alerts to improve safety.
