Fridge Temperature controller

[CorneliusAlphonse]

I inherited a minifridge when I moved into my current apartment. I have it almost ready to go for kegging but I am having one (very major) issue. The thermostat doesnt seem to work. No matter what setting I turn the knob to, the compressor just runs constantly, cooling everything in the fridge to -10 or -15.

I need a temperature regulator. I checked on homebrewtalk, they mostly recommend an aquarium temp controller (thread here) as a cost-effective solution.

Does anyone know where I could get one of these, or something else to supply power to my fridge depending on the temperature? (I'm an engineering student but mostly concrete, not electricity, so something I can figure out always preferred)

My first idea is the aquarium/fish store on Quinpool (close to where I live) but I don't know if they'll have it.

Cheers!

[JEH]

Im currently turning a chest freezer into a kegerator, and am buying a regulator from the NG for it. Im sure theres probably cheaper options but this is just easiest. That may work?

[CorneliusAlphonse]

Thanks for the response - I will check noble grape as well as it is right next to the fish place. I, for some reason, didn't think they would have it - would it matter which NG store I go to? I'll check Quinpool first

[mr x]

Christ. That thread is 63 pages long.....

[Jmac00]

the one at NG is $89.99 plus tax. I'm using the same one...managed to find it on kijiji for a bit less though. Works good, i use it on my keezer. If i find somewhere locally that sells the aquarium for decent price, i wouldn't mind building one like in the link...having the digital display would be a nice addition.

[CorneliusAlphonse]

Yeah, I just swung by NG and got quoted $89 for the regulator. A little outside my price range for this fridge, I could pick up a used full size fridge for less if I watch kijiji. The tropical fish store was a no-go as well.

I guess I'll have to keep bottling until I can get this fridge sorted.

[akr71]

In the meantime, at -10/-15 you could store hops in it.

[Jmac00]

before i went with the external temp controller for my keezer....i was going to do the internal one...switch the freezer thermostat for a fridge thermostat...but then didn't want to get into wiring it up.

if i were you, i'd take the thermostat out...then take it to an appliance repair place for a replacement. I priced a universal one when i was thinking about going that route, and they were like 30 bucks for a fridge. Good luck

[Garak]

I could build a simple controller for less than $20 in parts. I think I got most everything here except for a suitable relay.

It would just be a atmega48($2.20) micro-controller, a lm35($0.50) temperature sensor, a relay driver circuit(junk box parts ~$1) and the relay($2-10). It would also require a few other components from the junk box, a prototyping board, voltage regulator and a wall wort. It won't be the prettiest thing, I'll leave you to find a box to hide it in.

I already have the code written for another project. I could pre-program in the startup and cutoff temperatures for the compressor. The original project is for controlling fermentation temperature and was designed to be connected to a PC via USB to set temperatures in four zones and for monitoring/data recording.

[mr x]

Did I already say ?

[chalmers]

Garak, I know myself and several other people who are looking for reasonably priced temp controllers (for fridges/freezers, or for fermenter heating pads). Would these be something you'd be able to put together for us? The USB control might be a bit beyond what I was looking for, but sounds like a cool idea for the future.

[Garak]

I could build a few of these no problem. The main thing I don't have a cheap source for is a project box to put them in. Something along the lines of a water tight duplex electrical box would work great.

USB is the easiest/cheapest user interface. Its a fraction of the cost of adding an LCD or LED display and buttons. It just takes a USB-Serial breakout board from sparkfun which are usually around $15 US but I picked up 8 of them for $5 each on clearance a while back. The fermentation temp controller just comes up as a serial device(COM) in windows and works with any terminal program like hyperterminal or Putty. The interface is a simple keyboard driven program that allows you to set the cut in and cut off temp for a compressor or heating element. It could be setup for both heating and cooling. Settings are saved in non volatile eeprom memory so they are not lost when power is cut.

If anyone has any brewing project ideas needing electronics I'm more than willing to help out in exchange for old brewing/kegging equipment, exchange of services or even just a few beer

[akr71]

I would love a stir plate! I have most of the pieces already. An old hard drive for the magnets and old power supply for the rocker switch & fan. I'm just missing a potentiometer and the smarts to wire the thing together.

This is the plan I was going to follow.

[CorneliusAlphonse]

Thanks for the offer - maybe others will be interested in it - I've already ordered the $26 aquarium regulator from ebay, waiting on shipping (apparently, it could be a month or two if it gets caught in customs, coming from Hong Kong). I'll post some info and pics here when it arrives and I get it working.

[chalmers]

I could build a few of these no problem. The main thing I don't have a cheap source for is a project box to put them in. Something along the lines of a water tight duplex electrical box would work great.

USB is the easiest/cheapest user interface. Its a fraction of the cost of adding an LCD or LED display and buttons. It just takes a USB-Serial breakout board from sparkfun which are usually around $15 US but I picked up 8 of them for $5 each on clearance a while back. The fermentation temp controller just comes up as a serial device(COM) in windows and works with any terminal program like hyperterminal or Putty. The interface is a simple keyboard driven program that allows you to set the cut in and cut off temp for a compressor or heating element. It could be setup for both heating and cooling. Settings are saved in non volatile eeprom memory so they are not lost when power is cut.

If anyone has any brewing project ideas needing electronics I'm more than willing to help out in exchange for old brewing/kegging equipment, exchange of services or even just a few beer

Aha, didn't realize it would just only require USB/serial to setup, but afterwords could run independently. That doesn't scare me so much now.

LiverDance just bought a tight (in all senses of the word) looking electrical box. Where'd you get that one, and how much was it?

I am more than happy to pay for the materials and your time, and we can test it/them over a few pints of homebrew.

[LiverDance]

Picked up the box at Kent I do believe, it was around $7.

[Garak]

2011-02-09 12.32.16.jpg

2011-02-09 12.32.33.jpg

akr71:
I just put that stirrer together on my bench. It works ok. The spacing has to be just right. Too close and the magnet just jams the stirrer against the bottom. To far and there isn't enough magnetic coupling to turn the stirrer(is that even a word?). I'm using a screwdriver bit as the stirrer at the moment. A proper stirrer in a proper flask would work a lot better I'm thinking. The only thing I could find here with a thin flat bottom was a Tupperware container. A Pot doesn't work so well as a speed controller, it limits the current too much. I've got a few ideas to try.

[akr71]

DAMN! You did that in an hour and a half since I posted it? I am seriously impressed!

[Garak]

I had all the parts sitting under the bench, its not like its a finished product or anything, just a mock up if anything.

I wish I had a real flask to try it with. Everything else I could find in my kitchen has dome shaped bottom.

[mr x]

I have a spare flask over here in Hfx. And a stir bar IIRC.

[ratchet]

if you don't, I can likely put my hands on one fairly quickly.


you'll want to wash it off pretty good before you use it though

[gyorke]

I built a couple controllers using attiny88s and LCDs similar to these : http://cgi.ebay.ca/ws/eBayISAPI.dll?Vie ... 0509763097. Allows for a simple display. I would be happy to share the source code. For electronic project supplies I use digikey.ca , good prices and fast $8 shipping.

[Jmac00]

I'd be possibly interested in one of these if someone decides to make some. One quick question though....what do you use for the temp probe?

[ratchet]

usually a thermocouple.

you can buy em' pre-made, or just buy thermocouple wire and make your own.

[mr x]

I have lots of K type if anybody needs some.