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  • Gas Leakage Alarm Circuit

  • Created: Aug 27, 2014

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Kitchen is the place where we cook our foods and is the most vulnerable to explosion and fire. And it is usually caused by the ignition of an unnoticed gas leak. This project may prevent an unexpected event by detecting a Gas leak that can be used in domestic and industrial application.

The MQ-6 semiconductor gas sensor has high sensitivity to LPG, propane, and butane. It is also good in detecting combustible gases. The sensor can measure concentrations of 300 to 10,000 ppm and operate at temperatures from -10 to 50°C. The sensor is made of a sensitive material tin dioxide (SnO₂), which with lower conductivity in clean air and have higher conductivity along with the gas concentration rising. Connecting five volts across the heating (H) pins of the MQ-6 keeps the sensor hot enough to function correctly and connecting five volts at either the A or B pins causes the sensor to emit an analog voltage on the other pins.

The analog output voltage of the MQ-6 is connected to the reset pin of the ICM7555 timer astable multivibrator. The ICM7555 remain in the reset state when the output voltage of MQ-6 is LOW. And when the output is HIGH, the ICM7555 will work as a pulse generator that will switch the indicators (LED and buzzer) ON. The sensitivity of the sensor can be calibrated by the trimmer resistor connected between the output pins of MQ-6 and the ground. The pitch or frequency of the indicator can be adjusted by the variable resistor configured at pins 2, 6, and 7 of the ICM7555.



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