Gas Leakage Alarm using IC 555

In todays time everyone uses LPG gas at homes. Since the LPG is heavier than air so it tends to settle down along the floors and may results in dangerous fire or even a blast.
So in this project we will learn how to make a LPG Gas Leakage Alarm using IC555.

 

First figure (fig. 1) shows the circuit of the gas leakage alarm. The circuit operates off a 9V PP3 battery. Zener diode ZD1 is used to convert 9V into 5V DC to drive the gas sensor module.

The SEN-1327 gas sensor module from RhydoLABZ is used in this circuit. Its output goes high when the gas level reaches or exceeds certain point. A preset in the module is used to set the threshold. Interfacing with the sensor module is done through a 4-pin SIP header.  

 Fig. 1. Circuit for gass leakage alarm using IC555

In the second figure (fig. 2.) the pin details of the gas detector module is shown. Here in this project we will use MQ-6 gas sensor which is highly sensitive to propane, butane, isobutene, LPG, natural gas etc.

Whenever there is LPG concentration of 1000 ppm (parts per million) in the area, the OUT pin of the sensor module goes high. This signal drives timer IC 555, which is wired as an astable multivibrator. The multivibrator basically works as a tone generator.

Output pin 3 of IC 555 is connected to LED1 and speaker-driver transistor SL100 through current-limiting resistors R5 and R4, respectively. LED1 glows 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. 

 

         Fig. 2.