$5 Mini USB Fridge!

Step 3: Attch a USB Cable

$C:\Users\Ross\Desktop\cooler\f5.JPG$

Peltier units are designed to operate at a voltage between 3-12 volts, and the 5 volts from your USB port work just fine. Although the amperage could ideally be higher, the 500 mw output is acceptable. Cut away the end of an old USB cable (or pick up a cheapy) and strip back a couple of inches of the plastic covering. Inside you will find 4 wires, usually within a braided or thin aluminum shield. The wire colors will be white, green, red, and black. Trim back the white and green wires, strip off a small bit of the black and red wires, and solder them to the red and black wires of the peltier unit. Wrap with electrical tape or use heatshrink tubing. If you need information on correct soldering procedure or the use of heatshrink tubing, there are many excellent Instructables that will gve you all the information you need, simply do a search!

Optionally, you can attach a 1K limiting resister in between the red and black wires, although you are quite safe at the voltage and mA to not really need one.

Now, plug in your USB cable to a USB port on your PC, and within about 30 seconds you will be able to feel one heatsink become very cool while the other becomes warm. Note which heatsink becomes cool, as that's what we'll want to encase inside the mini fridge.

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amazehehe says: Nov 1, 2010. 7:01 AM

is there a peltier unit on the pc coolers? the ones with heatsinks

MooTaters in reply to amazeheheJan 18, 2011. 11:31 PM

CPU heat sinks usually have thermal paste which is a compound made to help with the transfer of heat. I believe they generally have properties which help that transfer heat, but mostly are used to fill in the tiny small spaces on the metal surface to create better contact between the two surfaces. Sometimes people use very high grit sand paper to smooth the surface even more to get better heat transfer allowing for lower temperatures. Thermal pads have been used in the past too which is a wax like material that will melt from the heat filling in those crevices, but that is rarely used these days.

codongolev in reply to amazeheheNov 17, 2010. 1:32 PM

sometimes, but that's usually only for really legit computers (overclocked and the like). most compys just have a heatsink and a fan.

MooTaters in reply to codongolevJan 18, 2011. 2:45 PM

Aren't you thinking of Phase change cooling? I'm not quite sure if it's the same technology or not. But that's what competition overclockers sometimes use unless they are lucky enough to have liquid hydrogen or nitrogen.

codongolev in reply to MooTatersJan 26, 2011. 6:24 PM

back in those days, I was misinformed.

yeah, I would expect a computer to be fried without thermal paste. it is definitely necessary.

macman808 says: Aug 22, 2010. 11:14 PM

is the peltier polarit protective because you could add a switch to change the polarity so that when the switch was flicked over the hot and cold sides would swap?

ALE777 says: Apr 4, 2010. 7:59 AM

Dear Friend: What a nice proyect did you post! I want to make some similar fridge with a peltier cell I have buyed, but I am troubled with the attaching the heatsinks to both sides of the peltier cell... How did you attached the two heatsinks? Did you use screws? (Because in the photographs are not clear). If so, there aren't a small heat transfer across the metal screws? or there are other methods to attach the heatsinks? Anyone that can answer my request, sincerely, THANKS!!!

knektek in reply to ALE777Apr 19, 2010. 12:29 PM

you need to use thermal paste to make a better contact between the peltier and the heatsink

josejovel17 in reply to ALE777Apr 7, 2010. 11:38 AM

WELL ON THE COLD SIDE YOU CAN TAPE THE PELTIER TO THE HEATSINK THEN YOU SCREW THE HOT HEATSINK TO THE COLD HEAT SINK LEAVING THE PELTIER IN BETWEEN BUT NO YOU CANT SCREW THE PELTIER, YOU GONNA MESS IT UP

colesdaddy2002 says: Jan 8, 2010. 1:58 PM

I didn't make a single drink cooler lol but cool idea, I actually took apart a coleman 12 v cooler and used the mini unit inside of my computer case I just cut out the back side where the big fan was mounted and mounted the cooling system from the cooler there, I got the Idea when we were camping this past summer when my buddy an I were talking about his computer over heating when he plays games that suck all the power his comp has to offer and his CPU was getting up to 120-130 degree's and shutting down, so beyond my wifes better judgement i ripped apart a 90 dollar cooler and did this, now my computer stays about 48 degree's F. and it works great.

colesdaddy2002 in reply to colesdaddy2002Jan 8, 2010. 2:05 PM

oh yes I forgot to add you do need to insulate the case and use a air drying system for this to work properly I just used some 1/4 inch Styrofoam and covered it with anti-static plastic to insulate the case

z28se says: Aug 22, 2008. 1:05 AM

wow you can also make a warming device

tyster in reply to z28seAug 24, 2009. 12:15 PM

I guess you could do both, Z28se. If a peltier units simply forces a temperature difference, then you could have two insulated containers back-to-back with the peltier unit mounted between the two. One side would be a little below room temperature and the other side will be a little above room temperature.

M F in reply to tysterAug 30, 2009. 1:38 PM

your idea will need some planning. there must be heat escape off of the hot side in order for the other side to get cold. If you add another insulated container to the hot side it will not be able to let heat out. it may not work right. let me know what you get. You should be able to do it if you add another heatsink to the top of the second hot box to let heat out. just use a smaller one.Let me know what you get.

dagenius in reply to M FAug 30, 2009. 1:43 PM

why would you want to let heat out if you were using it as a heater?

tyster in reply to dageniusAug 30, 2009. 8:48 PM

Oh, I think I see. The peltier unit generates heat. I would imagine that most of the energy it draws would end up coming off the hot plate (maybe both) as heat. If the peltier unit forces a fixed temperature difference between the plates, then as the hot plate gets hotter, the cold plate will also rise in temperature. So, for example, if you force a 20 deg. Fahrenheit temperature difference between the plate, then the peltier unit is producing something like 30 Watts of heat. The hot plate may get up to 100 deg. F, which would make the cold plate 80 deg. Hardly a cooler at all, but the peltier unit would make an easy heater, to have a warming box or plate this way. This is all just speculation; I never tried this... yet.

H3xx in reply to tysterSep 24, 2009. 9:03 PM

Yes and the cooler you make the hotplate the colder the cold plate gets. Using a liquid cooling system and 2 or 3 peltier units arranged C|H+C|H+C|H+L where C= cold plate, H= hotplate, and L= Liquid cooler, it is possible to get some pretty wicked temperature changes. It is in no way energy efficient mind you, but you can cool something below ambient temps. And before someone slaps a few of these in their computer case like i have described, if you do get below ambient temperatures, you'll need to insulate your case and dry the air inside, or else you'll get condensation. Like the water on the outside of a cold glass. It will kill your system.

H3xx in reply to H3xxSep 24, 2009. 9:06 PM

Also make sure you wire it correctly, lest you start heating the thing you want to cool.

justin.jackson in reply to H3xxOct 4, 2009. 7:33 PM

would switching the polarity of the wiring make it go from cooling to heating and vice-versa?

H3xx in reply to justin.jacksonOct 5, 2009. 5:09 PM

Yes it would. Many of the cheap store bought thermoelectric coolers simply use a switch to reverse the leads on the peltier. Simple really.

dagenius in reply to tysterAug 31, 2009. 5:22 AM

Very good speculation.

tyster says: Aug 24, 2009. 12:11 PM

Not sure how the current is controlled. There is a 500mW output, so at 5 volts, there is 100mA (0.1 Amps). My understanding of electronics is that the power supply, which is a voltage regulator controls the voltage, but the device controls the amount of current drawn from the power supply. If the peltier unit demands 5 Amps (2.5 Watts), then the power supply and USB channel would supply it and/or fry. Does the USB power supply have some sort of current limiter? In other words, if you short +5V to ground or allow a large current through, would the USB port be damaged?

M F in reply to tysterAug 30, 2009. 1:48 PM

a better way than that is to just use the 12 volt power coming off of the powersupply.
For those that don't know, every computer has 2 voltages going to each harddrivbe and device. a 5 volt and a 12 volt.
check the following picture, you will see a red wire,black wire, black wire,yellow wire.
The first red and black are for 5 volts.
The next black and yellow are for 12 volts.
also check for polarity.
http://educations.newegg.com/category/58/buy/image04.jpg
ps: if you use this method add an on/off switch.
http://www.epanorama.net/documents/pc/pcpsu_connector.html

sgt_pinky in reply to M FAug 30, 2009. 10:38 PM

On this, a typical average PSU (say 350-400W) can put out 15A on 12V or 25A on 5V - so it's much better to wire her straight into that than use USB in my opinion. However, you lose the portability aspect.

gamer in reply to M FAug 30, 2009. 8:01 PM

ps... not every computer... laptop harddrives and devices work off 5 volts... and some even 3.3 volts

M F in reply to tysterAug 30, 2009. 1:24 PM

(removed by author or community request)

M F in reply to M FAug 30, 2009. 1:33 PM

oops- correction. yellow wire is 12vdc. red wire is 5vdc.

thermoelectric in reply to tysterAug 24, 2009. 2:21 PM

The USB port has a current limiter, You have do get special electronics that request a higher mA from the USB port, But you can only request up to 500mA

79spitfire says: Aug 30, 2009. 9:55 PM

A Peltier junction does not "generate" heat or cold, it transfers heat from the "cold" side to the "hot" side, much in the same way an air conditioner transfers "removes" heat from the evaporator and gives it up in the condenser, except the peltier junction has no moving parts. If I'm not mistaken, reversing the polarity of the unit reverses the direction of the heat movement on many units, so merely providing a switch to reverse polarity will give you a "cooler-warmer" unit so if your using your computer out in the cold, you can keep your coffee warm...