The project detects flammable gases (LPG, butane, propane, methane, methane, methane, methane, methane, alcohol, hydrogen, and methane.) via the MQ2 Gas Sensor. When a flammable gas is detected the frequency of the speaker beep increases. The whole enchilada is controlled by a PICAXE 08M uController and some custom code.
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Here is a video of the system operating. Keep reading if you want the details.
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The rig gets its power from a 5VDC USB port (Windows and Mac compatible ;) or a car USB charger).
Via the headphone jack programming port allowing we can easily reprogram the PICAXE if we want to change the rigs personality. Such as, make the speaker beep faster, louder, flash lights, etc.
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The build schematic:
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Here is a video of the rig working on the bench. The current thinking at this time was to use a servo motor to move a needle over a calibrated meter. In the final design the beeping speaker was used to reduce the size.
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Here is a video of the rig working on the bench. The current thinking at this time was to use a servo motor to move a needle over a calibrated meter. In the final design the beeping speaker was used to reduce the size.
The source code for the PICAXE 08M is straightforward:
;
#picaxe08m
#com 11
main:
readadc C.2,b0 ; read the MQ2
sound B.1,(119,5) ; make a sound
w1 = 255 - b0
w1 = w1 * 5
pause w1 ; decrease pause between beeps if gas detected
goto main ; loop back to start
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