Good afternoon all. I wanted to show you guys my project and possibly get some feedback. I home brew beer and, during the (Texas) summer, I have a problem keeping my house at a temperature that is within the ideal conditions required for the yeast to thrive during the fermentation process. So a common solution to this is to create a fermentation chamber to allow your beer to ferment in a controlled environment. Many people use a chest freezer with an additional thermostat for this. There are a couple non-programmable thermostats available that work very well.
However, when brewing a lager-type beer, a more complex temperature profile is required for ideal fermenting conditions. For instance, a typical lager fermentation could be: Lower the temperature from 76 to 52 degrees over a period of 24 hours, hold temp at 52 for 10 days. Slowly raise temperature to 68 degrees over a period of 24-48 hours, then lower the temp to 34 degrees over a period of 48 hours and then keep it at 34 for 6 weeks.
This sequence of temperature is a lot of work and dedication (especially for someone with as short of an attention span as myself) for a manual thermostat. So I have created a programmable thermostat to control my fermentation chamber. I created it with a PIC18F microcontroller, a TMP36 temperature reading IC, and a relay. I created a user interface with the help of a 16x2 character LCD and an up/down/select keypad arrangement.
I have a 'Default Lager' program built into the thermostat (not surprisingly, very similar to the one described above), but I also added a function to be able to create your own temperature profile or edit a currently saved one.
I have added functionality for the user to navigate through the program to any stage/time the user wants.
Here’s a picture of what it looks like:
I’ve just finished up with this, I am currently testing it out and working out a few little bugs here and there, but I hope to be able to put this to work very soon. Being able to brew lager-type beers opens up a whole new set of beer recipes to brew (and drink! :))
I have updated some blog posts throughout the development process. Check it out here if you like: http://ohmbrew.blogspot.com