ocwo92
Well-Known Member
Note to moderator: I realized only too late that the DIY forum is be a better choice for this entry. By all means, feel free to move it.
Sure, there are plenty of temperature controllers for freezers out there already, but that's no excuse for piecing yet another one together yourself.
So, I constructed my second temperature controller for a second-hand freezer, which has room for just one fermentation bucket with no air lock. (But, a plastic bag and a rubber band works fine.)
It's a PI controller, and in the first version shown in the attached picture, the buttons are used only to set the desired temperature. Inside of the controller, a ZigBee radio is connected to my home ZigBee radio network, allowing me to set the controller parameters (including, of course, the desired temperature). The controller periodically sends its status via the ZigBee radio to a data logger.
The attached graph shows the temperature since March 18. On March 31, I raised the temperature for a diacetyl rest, and from April 4 and henceforth, I dropped the temperature manually. Then on April 7, I racked the beer to secondary and wrote a script for our home server to contiuously lower the temperature, so from April 8, the temperature has dropped linearly.
The temperature deviations can easily be reduced, but I decided that the freezer's compressor should be turned on for at least two minutes at a time, and only be re-enabled after a while, because otherwise I'd risk reducing its lifetime significantly. The temperature measures the surrounding air temperatur, so the temperature of the beer itself will hardly vary at all. (Except that it will be dropping at a constant rate at the moment.)
The next version of the controller allows the user (that is, myself and a few friends) to configure everything via an LCD menu and three buttons. Also, I've thrown together a Windows program that allows the user to configure the controller via USB or a ZigBee dongle.
Sure, there are plenty of temperature controllers for freezers out there already, but that's no excuse for piecing yet another one together yourself.
So, I constructed my second temperature controller for a second-hand freezer, which has room for just one fermentation bucket with no air lock. (But, a plastic bag and a rubber band works fine.)
It's a PI controller, and in the first version shown in the attached picture, the buttons are used only to set the desired temperature. Inside of the controller, a ZigBee radio is connected to my home ZigBee radio network, allowing me to set the controller parameters (including, of course, the desired temperature). The controller periodically sends its status via the ZigBee radio to a data logger.
The attached graph shows the temperature since March 18. On March 31, I raised the temperature for a diacetyl rest, and from April 4 and henceforth, I dropped the temperature manually. Then on April 7, I racked the beer to secondary and wrote a script for our home server to contiuously lower the temperature, so from April 8, the temperature has dropped linearly.
The temperature deviations can easily be reduced, but I decided that the freezer's compressor should be turned on for at least two minutes at a time, and only be re-enabled after a while, because otherwise I'd risk reducing its lifetime significantly. The temperature measures the surrounding air temperatur, so the temperature of the beer itself will hardly vary at all. (Except that it will be dropping at a constant rate at the moment.)
The next version of the controller allows the user (that is, myself and a few friends) to configure everything via an LCD menu and three buttons. Also, I've thrown together a Windows program that allows the user to configure the controller via USB or a ZigBee dongle.
