Peltier Power Supplies and Auctions: Scoring A Great High-Current DC Supply For Cheap!

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OddOne here, back on the attack with yet another article. This time, it’s a quickie.

Thermoelectric cooling modules (or TECs, often nicknamed “Peltier” modules after the effect they use to operate) are seeing increasing use in high-performance computing as a way to move heat off the tiny but thermally sensitive surfaces of the processor. TECs are relatively cheap, small, lightweight, and have no moving parts.

However, they consume an almost insane amount of power to run – 50 watts is often a bare minimum and really hot-natured chips like the AMD “Thunderbird” series of Athlon processors need TECs that draw 100 watts or more of power continuously.

When you’re already using 200-250 watts to run the computer, adding the TEC to the computer’s power supply often exceeds its capability and bad things happen as a result. So a second power supply is often employed to compensate for this.

That workaround has its own problem – a computer’s power supply might produce plenty of current but not enough voltage to feed the TEC its ideal diet of power.

Most 12-volt TECs are rated for 16 volts maximum and hit their efficiency peak at about 85% of their maximum ratings (about 14 volts), which is too high for a traditional computer power supply to produce. So, your 100-watt (6.2 amps at 16 volt max.) TEC might only be getting 70 watts (5.8 amps at 12 volts) of feed instead of the more ideal 85 watts, and that could very well translate to a few critically important degrees C.

There’s a better solution – an extra power supply that supplies plenty of current at 13.8 volts or so, or can be adjusted to as high as 15 volts. Such power supplies are NOT cheap. $200 for a 20 amp linear supply seems a common value, and switching supplies are even pricier.

However, if you’re willing to take a slight risk, you might be able to find a serious power supply for a laughably cheap price on an online auction! I picked up an adjustable-output switching supply rated for 21 amps at 12 volts, decreasing to 17 amps at 15 volts, for less than $20.

Naturally, the principle of caveat emptor – buyer beware! – applies here, so research the seller thoroughly.

What I did was this:

I pointed my browser to eBay and surfed the categories to find Photo & Electronics > Consumer Electronics > Test Equipment, which is where the power supplies tend to be categorized.

Other eBay categories that are good to search for PSUs are:

Photo & Electronics > Consumer Electronics > Radio: Ham
Photo & Electronics > Consumer Electronics > Radio Equipment
Photo & Electronics > Consumer Electronics > Electronic Parts
Photo & Electronics > Consumer Electronics > General

Searching all of eBay is generally NOT advisable as you’ll get a ton (literally thousands) of hits off every computer offered on eBay since these all have power supplies.

By narrowing the search to a specific category at a time, one can weed out the computer PSUs and concentrate on the more useful high-current linear or switching supplies.

Anyway, at the upper-right corner there’s a search box, so I put a check in the “search only in” box, typed “power supply” (without the quotes) into the box, and clicked Search.

First thing that came up this time was an Astron RS12A 12 volt 12 amp linear supply that ended at $45.

When I found a supply that looked good, I researched it in detail at its manufacturer’s website. If I like what I see, I research the seller and read up on the seller’s feedback, past sales, and current terms and policies. I ask the seller questions about the goods to make sure all is well. Then, if I am satisfied with all of the above I fire out a bid.

Got myself a 250-watt 12-15 volt switching power supply for $17.50 this way.

It’s a pulled-from-new-equipment supply but it tested fine, running my spare 52-watt TEC (thanks!) at 45 watts (~3.2 amps at 14 volts) without any problems whatsoever and holding the supply voltage to precisely 14.000 volts DC. (Took some seriously fine twitching to set the output adjust that precisely.) And, at 12” x 5” x 3” it fits inside my case, completing my stealth madly-overclocked computer.

Remember, auctions are “buyer beware” all the way, and you could get screwed out of some hard-earned $. But, if you’re careful and do your homework you can score a high-current power supply for your TEC(s) at a very good price.

I just looked up the supply I bought off eBay, a Power
One SPL250-1012. Digi-Key lists it for $345.00 each,
and Allied Electronics lists it for $456.65 in
less-than-10 qty.

I paid $17.50 + $12 for 3-day shipping. So I spent
less than $30 total for it. Hmmm, 90% off retail…

eBay is our friend.

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