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Measures the alcohol in your breath and marks the highest for a competition with your friends

Hi, this is my breathalyzer project. It's just something fun that I have been wanting to make for a while now. It uses an atmega328, alcohol gas sensor from Sparkfun, and a small graphic lcd from Sparkfun. It is very simple in operation.

1.When first turned on, it goes through a 45 second warm up period so the alcohol gas sensor has time to warm up.


2.After the warm up period, the screen says that the breathalyzer is ready for you to blow into. The dot above the bar shows the value that the sensor has to pass to reset to the ready state.


3.When you are ready to blow, you close the lid and blow into the hole on the longer side of the altoids tin.


4. After you blow into the breathalyzer, it shows you the maximum value that you blew and goes into the waiting mode. It also marks a dot above the bar at the highest value that was blown since being turned on.


5.Once the sensor reading passes the first dot, the breathalyzer goes back into the ready state and still shows the highest value blown.

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That's sweet. A truly entertaining project :D

Hi Ricco, nice project.

I bought a few of those sensors also.    with the same idea in mind.

what kind of calibration issues did you have to deal with?

what was the design source for your circuit?  did you design it yourself?


Well there actually is no calibration because the sensor's reading varies with many factors like temperature, humitidy, etc. The bar graph is just displaying the analog value from the sensor from 0 to 1023. For the curcuit I just used the example from the "arduino example" link on the alcohol sensor's product page at sparkfun.