A question for those knowledgable in DC electricity...
 

Well, as a high school science experiment (yes I know its a cheesy way to get a peltier cooled system :) ) I'd like to set up a water cooled peltier rig on one of my few AMD systems around the house. I completely understand everything I need to do to set this up but I am at a loss on how to incorporate a variable into this project. What I want to know is, is there a way that I can dynamically adjust the amount of power (via a rheostat, or possible some rigged DC circuit) going to the peltier. The idea is I want to see at what level of input will the peltier provide the maximum amount of cooling (as I have read around, more doesn't necessarily mean better). Is there any easy way for me to do this (I have looked for rheostats that accomodate the large amount of power I am looking at with this setup, and the only ones I could find rated high enough were mondo money). I have seen a few other similar posts, but the replies have been vague, or led to sites that didn't provide adequate information. If anyone has a suggestion, it would be much appreciated. Thanks!

Pat Razzino
Coolman

Just buy a benchtop power supply that lets you adjust voltage. Check shortwave radio stores for used ones in the 0-24V range :)

Other interesting variable:
cold plate clamping pressure (this is a BIG one)

Maybe some cost benefit analysis with an estimate on cost of powering the pelt and the increase in o/c from straight water cooling? Compare to the cost of a higher speed chip for example.

Thanks for your promptness in replying.. sounds like a plan provided I can find one cheap enough (gah, which leads to the biggest of all problems -- finding a way to finance this without pissing anyone off :) ).. Also a question.. if I chose a beefier peltier (say 172 watt) and I kick the voltage down a couple of volts, (this is probably a stupid question, but necessary to clear all doubts I have) will in turn the amount of current being drawn from the bench supply increase? and.. if so I will want to know ahead of time not to overdraw my power supply, correct? Thanks again I wasn't expecting a reply so soon :)

Pat Razzino

No. The current will decrease when you lower the voltage.
All you have to find is a variable PSU that is able to supply the max rated amperage that your peltier needs.

Good luck on your experiment:)

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1762769812

only 13.5-16.5V, but it is a hell of a pelt PSU at a great price :)

Thanks for the help guys.. that supply looks tempting, but I don't quite see how they adjust the output voltage, there is no clear indication of this, aside from graphs showing work load vs input voltage. I think ill head down to a ham radio shop and have a look around, maybe get lucky. Thanks for all of your help I really do appreciate it :D.

Well on second thought if one of you could explain to me more clearly how exactly to adjust the output voltage on the supply in the ebay link I will snatch it up :). Also it looks as if I'd have to find (possibly strip?) an ac cable to get the juice flowing.. Well again thank you.

This PSU is spec'd with a 10% adjustable output. It probably has an adjustment point, like a hole in the case where you'd stick a small screwdriver.