[Shonen]

Seeing as we're always at Skidz's house and we're always consuming dranks and stuff, I thought it would be awesome to make a dranks fridge using TEC's (thermoelectric cooler), aka. Peltier Pads.

http://en.wikipedia....#Peltier_effect

http://business.shop...d=p3286.c0.m282

The gist of it is that when you apply current to the TEC pad, heat is absorbed on one side and emitted on the other (heat pump). We can take advantage of this by heatsinking the 'hot' side, and with enough forced induction (fan-cooled) the 'cold' side can get cool enough to freeze stuff. I have three extra PC power supplies that we can use to power the pads, although they are of high power (some of them exceed 500W @ 12v!) but if I make another PWM controller we can effectively temperature-control the fridge.

Still thinking about how to best connect the pads to the fridge while isolating it from the heatsink. I'm also not sure if I want to go with multiple low-wattage pads or a single high wattage one...keep in mind though that the psu's I have laying around are limited to 10A so more than 120W coolers cannot be run at full power. That said, the 5v rails are around 15A, so we can hook up smaller auxilary pads on there if we wish. Not sure if we can slightly overdrive the 12v rail(s) since none of the other voltages will be hooked up, but we'll go with the safe maximum they have.

Here are the specs of the extras I have:

Sparkle Power International 250W (lol I'm not even kidding)
12v: 7 amps
5v: 25 amps
3.3v: 15 amps

Enlight Corporation 250W
12v: 10 amps
5v: 25 amps
3.3v: 14 amps

Macron 300W
12v: 10 amps
5v: 30 amps
3.3v: 14 amps

Black Steel 580W (teh wad's borked one)
12v: 25 amps
5v: 36 amps
3.3v: 30 amps

(I don't understand why you'd need 30 amps at 3.3v, but there you go...)

[Shonen]

update: we have everything we need. we just have to put it together, lol.

I was playing with the peltier element last night, it's quite bizarre feeling one side get hot and the other side get cold without making any noise or vibration. The hot side does get extremely hot though, uncomfortable to hold even at 3.0A (around 4v), I was using my battery charger to pump current into it.

Hawaiian Legend gave me another heatsink today, but there's no mounting holes so.... :\ we might still use it since it's a good size (roughly the size of the Xbox 360 CPU heatsink, but with a more or less solid copper base.

as for thermal paste, I was gonna use AS Ceramique for the cold side (it's stable to -150C) and AS5 for the hot side (stable to 130C). Not that I think we'll get to that temperature anyway, but Ceramique in my experience is stickier and harder to use, so I figured we might as well use it for this.

Also, something I noticed with the Peltier element...when it's been used for awhile (ie. one side is hot and the other side is cold) and the power is removed, BOTH SIDES WILL HEAT UP. It should have been obvious to me but it's worth mentioning, since the heat pump is no longer active and the heat will sink to the other side. This may be a problem as that means the PWM controller will not be linear, as the 'off' states will conduct heat into the fridge.

Anyway, here's the PSU heirarchy I'm thinking of using
+12v
- Peltier
- large fans for peltier heatsink
+5v
- small fans for peltier coldsink
- status LED's
- PWM circuit power
- internal light
+5vSB
- auxilary peltier heatsink fan(s)

I've read in places that the 5v/3.3v line may have to have significant current (>500mA) being drawn for the PSU to remain active, which is why I'm trying to cram as much shit as possible there.

[Shonen]

man we gotta hurry up and build this thing before I destroy the Peltier unit by playing with it lol. heats up painfully fast (ask me how I know) when used with 14.4v. Since I don't wanna use thermal adhesive, I'm thinking of just making a bracket out of plexi or phenolic to hold the unit in place, and drill mounting holes in that.

unit dimensions
width (no wires): 39.54mm
height (one side wires): 39.59mm
thickness: 3.34mm

either way, I have two choices on what to do for the hot side heatsink...Hawaiian Legend gave me a huge one I wanna use, but I'm unsure if I want to lap it or just put some intermediate metal around the base (copper?) to widen the die contact area.

[Shonen]

since this is the easiest project to finish (we have everything required already, if we find a cooler) I think we should make this our priority lol. too many other stupid projects I wanna do already that's why.