How would one cool down a metal plate by electronic means...

[Madness]

...without the use of a fridge?

I don't have room in my unit for a spare fridge and thus I've been thinking that maybe I could sit my fermenter ontop of a metal plate which would some how be chilled and thus chill the fermenter to the correct brewing temp.

I've been looking at computer Cpu peltiers but not sure if I could get the control of the temp that maybe needed.

Also would there be a problem chilling the fermenter from the bottom ?

Any ideas fellas?

[Ash]

peltiers need big arse heatsinks & fans - plus if they eff up they can heat instead of cool.

Seriously a 2nd hand dunger fridge & a fridgemate isn't that dear

[KEG]

with enough big peltiers, a proper active cooling/heatsink method, an insulated enclosure around the whole thing with the cool side of the metal plate inside and the hot side/heatsinks outside, and a damn hefty power supply to run the peltiers, yeah, you could do it. but temp control would be a b!tch, and total cost would be more than a second hand fridge and a fridgemate.

[geoffclifton]

Peltiers are rediculously inefficient power wise. If you've got room for a fermenter then you've got room for a bar fridge, it's only a square box slightly bigger than the tub.

Cheers, Geoff.

[SpillsMostOfIt]

with enough big peltiers, a proper active cooling/heatsink method, an insulated enclosure around the whole thing with the cool side of the metal plate inside and the hot side/heatsinks outside, and a damn hefty power supply to run the peltiers, yeah, you could do it. but temp control would be a b!tch, and total cost would be more than a second hand fridge and a fridgemate.

I have such a thing for my fermenter. It's a Dome (brand) wine cooler that I ebayed and it seemed like it would suit my purposes at the time. The power supply is rated at 60W, which isn't horrible. It seems to be working fine, but it doesn't have the 'fast cool' power of a compressor-based fridge.

Because peltier effect devices are reversible in nature, I am toying with a homebrew fridgemate so the one cabinet can cool or warm, depending on the need.

Peltiers are not for everyone, but mine is kinda doing it for me.

[cleverpig]

This may suit your needs, http://www.oatleyelectronics.com/kits/k140a.html. However they seem to be sold out at the moment.

[SpillsMostOfIt]

I'm pretty much there with my own. I want to do this in the digital domain and am using a NetMedia BX-24 microcontroller (because I have one lying around) and two relays - one to switch the peltier on/off and one to change polarity of the electricity across it to go from heating to cooling and back again. The Oatley one is a simple analog comparator and probably not much different to what the manufacturer of my wine cooler has built into it.

My major issue to date has been with calibrating the thermistor. There's a dark art there that stays just out of my reach, but I am creeping up on it from behind (so to speak).

Oh... and... umm... I'm drinking a home brew...

[cleverpig]

Ah good stuff, BX-24 is that Atmel and basic ?

I was playing around with a PIC 18 using a DS1820 1-wire temperature device, and relays to drive a peltier.

Then i gave up on the peltier, thought it would be too inefficient, and a fridge would be cheaper and more effective in the long run.

Have not completed the micro controller as, i ended up hooking the 1-wire bus into my PC, and writing some Java to do temperature monitoring, now planing on adding a DS2408 switch, to allow switching of relays over the 1-wire bus. I can run multiple switches and temperature devices on the bus, allowing the switching of the fridge supply, and a light globe. I can also monitor outside temperature, ambient air temperature around the fermenter, and temperature within the fermenter.

oops nerd alert

[SpillsMostOfIt]

Yes - the BX-24 is based around one of the previous generation Atmel chips.

In Version Three of this thing, I will probably use an AtTiny 2313 (again because I have some lying around) and the WinAVR tool chain. But that will have to wait until my sample request from Maxim (for a DS18S20) is fulfilled...

I figure the wine cooler will do fine as a fermentation cabinet, but I would need a freezer for lagering. Good thing I prefer ales, eh?

Some of my best friends are nerds... No, really. I mean, not that there is anything wrong with that.

[cleverpig]

Getting samples of the 1-wire stuff from Dallas is the way to go. I did find http://www.futurlec.com sell the DS18S20 at 3.95US which is reasonable, but most of the other stuff is pretty hard to find for hobbyist prices.

I have not used the AVR chips, only programmed PIC chips so far, but have a few TI MSP430's, DS 8051's, and some Freescale chips in the parts bin. Would like to get my hands on the ARM micro's from Phillips being 32bit instruction set.

I've actually found that it's really only Dec,Jan,Feb that I need to lower the temperature of my primary. My downstairs area is double brick, it keeps cool down there. The rest of the time it needs heating.

Hopefully one day I'll get the switching going, and have full temperature control..... If i can ever finish a project that is, this electronics stuff seems to take up a lot of time, and I always get side tracked with other things.... hic

[SpillsMostOfIt]

Futurlec have the best prices going, but their customer service is at best variable.

I chose AVR over the PIC because it is a more modern design, is supported by gcc and requires almost no hardware to program. AVRx is cool. Having said that, there is much more info around on the PICs.

I apologise to all for the geek speak.

[gregb]

You fellas got an English translation for that ?

Cheers,
Greg

[SpillsMostOfIt]

You fellas got an English translation for that ?

Cheers,
Greg

I'll try...


Nope. Sorry. I hope I didn't get anyone's hopes up...

[cleverpig]

Now back to making beer.....