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Simple Gas Leak Detector Circuit
Here is the gas leakage circuit uses the SEN-1327 gas sensor module. Its output goes high when the gas level reaches or exceeds certain point. Interfacing with the sensor module is done through a 4-pin SIP header.
Pin details of the gas sensor module are shown in bellow picture An MQ-6 gas sensor is used in the gas sensor module. The sensor can also be used to detect combustible gases, especially methane.
Whenever there is LPG concentration of 1000 ppm (parts per million) in the area, the OUT pin of the sensor module goes high. The multivibrator basically works as a tone generator. This signal drives timer IC 555, which is wired as an astable multivibrator.
Output pin 3 of IC 555 is connected to LED1 and speaker-driver transistor SL100 through current-limiting resistors R5 and R4, respectively. LED1 ON and the alarm sounds to alert the user of gas leakage. The pitch of the tone can be changed by varying preset VR1. Use a suitable heat-sink for transistor SL100.
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