As both a hacker and a brewer this is extremely interesting. Building a temperature controller fermentation chamber is something I want to do at some point.
I did something similar, but with just a webcam and a laptop, and instead of beer it was mead. Basically, I pointed the webcam at the air lock, which produced a bubble every 15-30 seconds (depending on the fermentation process). I wrote a small Python program using PIL which processed webcam frames and detected sudden changes in the image (a bubble). Each time a bubble was detected, it would write an entry to a database (date, time_delta_from_last_bubble).
This was really cool when I went out of town because I could login and see the delta between bubbles gradually increasing, and once I saw it sitting at 40-50 seconds between bubbles for a day or so, I bottled it.
Nice! :) Although I have to interject: Air-lock activity is not always a great indicator of the fermentation process. You can have active fermentation without bubbling, so it's always Best Practice to instead take Gravity Readings. When the brew has produced consistent measurements for 3 days, it's safe to say your fermentation period is over and the beer has reached it's Terminal Gravity.
Absolutely, I agree with you 100%. This was a quick hack I had to do because of short notice trip. I wanted to be able to detect the amount of gas being released, but I had no time :(.
This seems much more complicated than is necessary. It costs ~$200 for a 7 ft^3 chest freezer and ~$50 for a fridge thermostat with the required temperature setpoints.
Totaly true, I'm thinking he could then look at expanding it into a beer-cooled PC setup. Practical would be a heating system that used hot water you heated up via a water cooled PC/running pipes via the cooling grid of the home freezer. That would be practical and yet has not been done but I think you will agree the beer-cooled PC does stands a better chance, just because it involves geeks and beer and I'll drink to that.
Actually if you look around some of the Chinese deal sites, you can find $50 ramp/soak PID temperature controllers. At that price, it's downright dumb to DIY.
I love all the various uses for a raspi. Our goal at the office is to build a raspi based kegbot - we will open source it once we are done (if we get around to finishing it!)
That's awesome! I wanted to add: There is a brewer/dev who has created an as-of-yet-conceptual project called "BrewPi", with a goal of producing an all-in-one amalgamation of Raspberry Pi and useful brewing tools.
And a consistent brewing process like nobody else in the world. And a taste that, while not satisfying to a heavy beer drinker, is palatable to almost everyone.
