A while ago I purchased myself an MQ-3 Alcohol Gas Sensor. This little device, according to documentation, runs off a 5V power supply and involves a heating implement.
Now, I've actually been meaning to use this thing via the Sparkfun breakout, but I have a dilemma. Some tutorials use a 9v to 5v converter to drive the sensor independent of the Arduino, while others power it directly from the Arduino's 5v supply. Which method is correct? Can I damage the arduino by driving the alcohol sensor from it?
MQ3 takes nearly 1W for the heater element. (5V, 200mA)
Feed from Arduino works fine if this is the only sensor fed and when connected to USB port ( max 500mA)
Now: If you disconnect from USB and feed from external (maybe 12V) source, the onboard regulator takes
a hit. It shall cope with 7V, 200+mA! 1.5W!
Do this test: Feed from USB for 2 mins. Feel the temp of MQ1 (opprox 1W)
Now think: How will the poor regulater on your Arduino board feel when dissapating even more heat?
It will probably not break, but I will not recommend it.
Use an external regulator (7805, TO220) or ather suitable power for the heater element
knut_ny:
MQ3 takes nearly 1W for the heater element. (5V, 200mA)
Feed from Arduino works fine if this is the only sensor fed and when connected to USB port ( max 500mA)
Now: If you disconnect from USB and feed from external (maybe 12V) source, the onboard regulator takes
a hit. It shall cope with 7V, 200+mA! 1.5W!
Do this test: Feed from USB for 2 mins. Feel the temp of MQ1 (opprox 1W)
Now think: How will the poor regulater on your Arduino board feel when dissapating even more heat?
It will probably not break, but I will not recommend it.
Use an external regulator (7805, TO220) or ather suitable power for the heater element
Alright, so Arduino powering won't go over well for my project.
The next step is building a regulator. I understand a 9v to 5v regulator with a battery pack is ideal. Are there any "idiot proof" schematics/instructions out there? The simpler the better.
