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Ruprect 05-22-2012 12:14 AM

Temp controller build
1 Attachment(s)
Due to a lack of viable options, I decided awhile back to create my own thermostat for my fermentation chamber.

After looking at the options available, I wasnít too excited about any of the temperature controllers I could find. The thought of having to update the temperature manually on a daily/hourly basis during a lager process doesnít really excite me or my ADD tendencies too much. So I set about making one of my own with the help of a temperature reading IC, a microcontroller and a relay to control a power outlet.

Despite getting a little carried away on some of the options/features, Iím pretty excited about the resulting product. I essentially come up with a digital controller that has an LCD screen on it to show the current stage of the fermentation process, number of days at the current stage, the actual temperature inside the chamber and the temperature you have it set to. It has the ability to control a fridge/freezer as well as a heating element of some sort.

The best part of the controller is that it has the ability to setup and change fermentation ďprogramsĒ. For instance, I can setup a lager fermentation program that will set the temperature at 52 degrees for 10 days, then slowly bring it up to 68 degrees over 2 days for a diacetyl rest, then gradually lower the temperature to 34 degrees for lagering.

You can create a program by adding stages. Each stage has a start temperature, a duration and a gradient. If you want to set a temperature and keep it, set the gradient to zero. If you want to lower the temperature 1 degree per day, you set the gradient to -1/day, or you can set the rate to drop 1 degree every 6 hours or whatever your heart desires.

Iím just now finishing up programming the code to store new programs. Outside of that, itís about ready to go. I have a chest freezer (thanks craigslist) with a fresh coat of paint on it and ready to go. I hope to be brewing my first lager here very soon!

Here are a pic of what it looks like:

Attachment 62068

I have also posted blog entries during the building process of the controller. Lots more pics and information can be found there.
You can check it out at this address if you like: ohmbrew.blogspot.com

**Disclaimer: There's plenty of geeky vernacular on there.

ClaudiusB 05-22-2012 12:30 AM


Originally Posted by Ruprect (Post 4105085)
Due to a lack of viable options, I decided awhile back to create my own thermostat for my fermentation chamber.

Great project:mug:


krazydave 05-22-2012 01:23 PM

Very cool! I wish I had the time to sit down and spend some more time learning circuit design and ultimately build something like this.

So... what was your total build cost on this bad boy? There's definitely a lot more crammed into that little box than I had guessed by looking at that first pic!

Ruprect 05-22-2012 03:26 PM

Thanks guys!

I'm probably up to around $100 or so in parts for this guy, but part of that cost was taken up with buying multiple parts in order to find the correct one. Plus I purchased some spares of several of the "finicky" components just in case I let the smoke out of them during development.

And yeah, the insides certainly take up more than I would have hoped. A good portion of the internals have to do with the power supply/conversion. I could have saved some space by using one of those blocky DC converters that are used for almost every piece of electronics. But since I needed both 120V AC (to power the freezer) as well as DC, I put the DC converter inside the box.

The wires connecting the LCD screen and buttons to the main board are also very bulky.

Yandle 02-21-2013 02:53 PM

Nice looking build! I had to piece mine together with out of the box tech like an STC-1000 temp controller and an outlet. I just got it up and running and it seems to be holding pretty well. I was already thinking about a lager to start with and manually stepping the temperature. Yours is awesome though, the ability to set it and forget it would definitely be handy!

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