[koslov]

Here's some questions I sent to info@variablepc.com:

Hello,

What kind of control logic do your VPC controllers use? Is it one of these: http://www.marlow.com/TechnicalInfo/power_supplies.htm ?

What have you changed in your design since it was reviewed here: http://overclockers.com/articles424/ ?

What is the highest recommended TEC model for your 225+ unit?

Thank you,

Koslov

And the reply:

Hi Koslov,
It is a modified proportional control.
The circuit originally was an on/off circuit...so that has changed.
The pot is different and allows for a wider range of adjustment.
There is a 'remote' available (180r, 200r, 225+) that allows you to mount the controls and leds away from the head unit.
The passive heat sinks are larger.

If you drive a 226watt peltier with the 225+ there is some 'head room' but I would not suggest trying to drive much more. Actively (fans) cooling the heat sink will add some stability (linearity) to the temp control. The driving mosfets are under-rated by 20% but the heat associated with controlling a 226 watt peltier is the most significant obstacle.

jim

So the model rating is for the max TEC rating, not output (odd that it clearly says "Output: 225WATTS-max" on the website). If you can adjust the voltages with the pot, I guess the 12.6 and 18 given are just nominal.

The McShane controllers look nice, but lack the dual probes if you are trying to keep that CPU at ambient. Not a problem if you're ambient temp doesn't vary greatly, but at least mine does. If you got the 5C7-350A kit ($62), you'd still need a probe, around $10. But they do have a probe that's < 1mm diameter! Then you need heatsinking and an enclosure perhaps. So it's definitely cheaper to DIY, but the savings aren't that big.

Hmm, both of these units look nice, but it'd be nice to see how well they work in practice. A review would be nice, but do you know any pHellows with temp equip?