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View Full Version : Varying TEC voltage


andersson.j
03-12-2006, 05:47 PM
Running peltier cooling 24/7 means that you'll always have lots of watts to cool no matter if the computer is just idling. This means that the radiator fans always have to spin very fast to cool the rad enough. While idling the TECs cold side is at it's coldest and hence the temperature difference between insulation and air will be at it's peak and so the risk of condensation will also be at it's peak. My computer usually idles during nights and then I'd rather have a silent computer then really low temps. It's also a big waste of energy (and hence money) to use hundreds of watts just to have low idle temps during night!

My peltier PSU is variable between 3V and 15V so I could just lower the voltage manually by simply turning a potentiometer, but thats just too easy...

I have a miniNG which I use to power my pumps, 2x Laing DDC-Ultras. It's got two output channels so I could put the pumps on one channel and use the second channel to control the peltier PSU. The miniNG is connected to a T-balancer XL so I can vary the miniNGs output voltage through software. I can even make it vary the output voltage automatically depending on any temperature.

This is how it's supposed to work:
If the cpu isn't working very hard it doesn't emit much heat and doesn't requier much cooling so the TEC doesn't have to run on full power. A tempsensor senses that the cpu temp is decreasing and reports this to the T-balancer that tells the miniNG to lower the output voltage to the PSU which then lowers the output voltage to the TEC. Now the water temperature decreases and my water temp probe senses this and reports it to the T-balancer which lowers the output voltage to the radiator fans, hence they emit less noice and I can sleep! :up:
Then I wake up and decide to game a bit before I go to school. The cpu temp increases and the whole process goes backwards which means louder fans and cooler components.

The only problem is the miniNG -> peltier PSU connection. I have to build a circuit that replaces the potentiometer. A voltage controlled resistor with a 0-12V input that varies the resistance between three wires between 0-10 kOhm. More details about the potentiometer can be found in my other thread How to build a voltage controlled resistor (http://www.xtremesystems.org/forums/showthread.php?t=92351) in the Xtreme mods section.

Shabubu
03-29-2006, 08:03 AM
Remember that the miniNG is controlled by the t-balancer software, but is independant of the t-balancer itself. You can only adjust the power of channel A using the channel A temp probe, and similar for B. Took me ages to get that sorted. Also remember that the power output for each channel in analogue mode is getting close to max with 1 DDC (25W max in analoque). So 2 on 1 channel is probably a bad idea.

ls7corvete
03-29-2006, 09:32 PM
Sounds good, if you get the circuit written up that would be great, there are plenty of devices that use a pot for control that could benefit from this. TECs are only one area of this.

It might be a good Idea to see how cool your TEC gets at 3v first as well.