A question for those knowledgable in DC electricity...

Coolman · 09-03-2002, 11:04 PM

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

pHaestus · 09-03-2002, 11:17 PM

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.

Coolman · 09-03-2002, 11:29 PM

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

Dix Dogfight · 09-04-2002, 01:03 AM

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

pHaestus · 09-04-2002, 12:18 PM

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

Coolman · 09-04-2002, 02:31 PM

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

.

Coolman · 09-04-2002, 02:37 PM

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.

bigben2k · 09-04-2002, 02:47 PM

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.

09-03-2002, 11:04 PM	#1
Coolman Cooling Neophyte Join Date: Sep 2002 Location: Northern VA Posts: 4	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

09-04-2002, 01:03 AM	#4
Dix Dogfight Cooling Savant Join Date: Aug 2001 Location: Stockholm Sweden Posts: 128	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 __________________ If it ain't broke, fix it. Setup: Dual Duron 1100 \| Voodoo 3 2000 \| Addtronics W8500(WTX) \| Eheim 1250 \| Car radiator \| 2 Innovatech WB \|

09-04-2002, 02:47 PM	#8
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	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. __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

09-03-2002, 11:17 PM	#2
pHaestus Big Player Making Big Money Join Date: Aug 2001 Location: irc.lostgeek.com #procooling.com Posts: 4,782	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.

09-03-2002, 11:29 PM	#3
Coolman Cooling Neophyte Join Date: Sep 2002 Location: Northern VA Posts: 4	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

09-04-2002, 12:18 PM	#5
pHaestus Big Player Making Big Money Join Date: Aug 2001 Location: irc.lostgeek.com #procooling.com Posts: 4,782	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

09-04-2002, 02:31 PM	#6
Coolman Cooling Neophyte Join Date: Sep 2002 Location: Northern VA Posts: 4	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 .

09-04-2002, 02:37 PM	#7
Coolman Cooling Neophyte Join Date: Sep 2002 Location: Northern VA Posts: 4	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.

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