Arduino Kegerator Temperature Controller - Home Brew Forums
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Old 05-24-2012, 01:35 AM   #1
luke_l
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Mar 2012
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So I have been slowly getting into kegging, and recently got a great deal on a small bar fridge, the Danby one which holds 2 cornies. I find that the factory temperature controller (in mine at least) pretty much sucks, and can't hold a constant temperature. I had a glass of water in it, for checking liquid temperature, and it would vary from 5C to frozen, so I had to do something. I decided to build an Arduino one with mostly stuff I had laying around, so it didn't cost me much. If you had to go from scratch, I would say around $20 probably (ebay prices). Basically, I have a temperature probe in the fridge which is a 'onewire' sensor, super easy to work with. The arduino can be set in 0.5 degree increments, and is currently programmed to keep it within 1 degree of that, and it also has a 5 minute compressor cool-down time programmed in. I built a remote "relay box" which also has the guts from a wall wart transformer, which feeds into the circuit board so that I don't need to have 2 things plugged in. Still need to build a box for the circuit board/LCD, but I am trying to decide what I want to do... might dremel out a cutout in the door for it, or in the bump on top near the front (bad for spillage once I install my taps).
I know the temperature is set kinda high, but I just got it going and want to make sure its accurate before I set it too cold
Let me know what you think!


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Old 05-24-2012, 01:42 AM   #2
HangLoose
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Apr 2009
NJ
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Nice. I built something like this but with a heater too. I used a Picaxe and a 40amp SSR instead of an arduino and a relay. I made it have an adjustable offset so there is a 'dead band' in there. That way you can run temps right where you want them sometimes, but other times when its less important you can let the temp come up 2 or 3 extra degrees before cooling again to help stop your compressor from short cycling.



 
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Old 05-24-2012, 01:50 AM   #3
luke_l
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Mar 2012
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Ya, I was thinking about making it adjustable, but didn't bother. I actually dont have buttons or anything for adjusting the temperature, since I dont know how I'm going to mount it... I'm just shorting pins right now to adjust it . I'm hoping it doesn't run too frequently at 1 degree, I might have to adjust that if so. Just realized when I went down to pour a pint, as soon as I open the door the temp jumps up (the sensor is too quick). Might need to put a trigger delay in...

I checked my ebay history, and here's what I paid for some of the stuff (approx).

LCD: $3
Relay: $3.75
Temp Sensor: $1
Atmega 328: $4
LM7805: $0.30
Proto Board: $0.20
Resitors/Caps: $0.50?
Wall Wart: Free (everyone has some kicking around...)

Total: $12.75

 
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Old 05-24-2012, 02:01 AM   #4
HangLoose
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Apr 2009
NJ
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Yeah its crazy how cheaply you can put this stuff together huh? What I do is either a: use a thermowell or b: tape the sensor probe to my keg then add insulation over that so that I'm more or less measuring the beer temp rather than the air temp.

 
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Old 05-24-2012, 02:31 AM   #5
luke_l
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Mar 2012
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Ya, I was trying to tape it to the keg, but duct tape wouldnt stick to the cold metal, and I was too lazy to get an elastic or something. Tomorrow I guess.

Ya, I build stupid little electronic "things" pretty frequently, it's so cheap, and much more fun than buying something. Only problem is I don't document anything, and then later when it's not working right I can't remember what I did in the first place, and end up repurposing the parts or something.

 
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Old 05-24-2012, 10:52 AM   #6
HangLoose
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Apr 2009
NJ
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I know the feeling. I now keep a little composition book with little drawings, snippets of code and the like. It makes life way easier. I even standardized things like temp probes so they all have the same plug, etc. It's nice.

 
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Old 06-14-2013, 05:13 AM   #7
delokaver
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Jun 2013
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can you please share the schematic and the arduino code for this ? is also possible to make this capable to hold the temperature up to 350 degree in celcius ? I have a fairly good Thermistor 100K . I was thinking to build this as a solder heater / station.

Thanks in advance

 
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Old 07-10-2013, 02:35 PM   #8
Abhitchc
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Jan 2013
Jackson, MS
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Quote:
Originally Posted by delokaver View Post
can you please share the schematic and the arduino code for this ? is also possible to make this capable to hold the temperature up to 350 degree in celcius ? I have a fairly good Thermistor 100K . I was thinking to build this as a solder heater / station.

Thanks in advance
this.

 
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Old 07-10-2013, 06:27 PM   #9
Indian_villager
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Apr 2010
Claymont, Delaware
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I too have been working on a controller for a kegerator. If you would share your code it would be much appreciated. I am interested in seeing how you set up the 5 min cool down interval.

 
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Old 07-30-2013, 12:39 PM   #10
SpargePervert
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Mar 2012
london, london
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Id also be keen to see the code.
I've been logging temps with an arduino and raspberry pi, and want to use it to control the fridge but am a bit concerned about knackering the compressor if I get it wrong.



 
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