We've got a brand-new built-in home entertainment center thing. Looks cool, but all of the stereo components go inside, which means cooling is an issue. The carpenters that built it included what looks like a generic PC case fan and left it to me to sort out what to do with it.

I've been thinking I should replace it with one of the temperature-sensitive fans (see, for example, the Thermaltake 120mm). The question is how I'm supposed to power and control the fan.

I could build a relay switch of some sort (like this) that triggers from my receiver's "12V trigger". I suppose I could potentially drive the fan directly from the 12V trigger connector, but I'm not sure I can draw that much current from it, and I think I might want the fan to run even after the amp is off, until the cabinet cools down.

Thoughts?

12v wallwart with a relay to a thermistor (which itself is powered by that wallwart) if the fan itself doesn't have one for on/off. Otherwise just 12v to a wallwart if the fan's own thermistor can turn it on/off. If you only want it on when your amp is on, then 12v wallwart to a relay and the relay controlled by the trigger connector. I wouldn't power it from the relay voltage directly.

Or... If you don't want the (fan's) wallwart sucking vampire current, then connect that to a power strip which has a relay circuit built-in. I'm sure there should be something like that around. I know there are all kinds of power controllers for HT that have this ability - at least I saw them at CES a few years back.

The amp's 12v trigger is only rated for 50mA. The fan in question wants 500mA, so that clearly won't do the job.

Given how many other wall-warts are floating around to drive all the doodads in the home theater, one more wall-wart isn't the end of the world, and the whole business goes to zero if I hit the great big power switch.

Presumably, that means I only need to get something like this and I'm done.

EDIT: Or they've got everything integrated and ready to go. That's probably the solution.

I went really over the top when I started looking at how to cool the little server room under my stairs. I set up 2 120mm almost silent PC fans, running them at 9v from a variable wallwart PSU. I used an x10 to control the fans as I had a spare module and a temp sensor the server could read.

In the end they were so silent, and the x10 so unreliable, that I just leave them on 24/7 now. They have been running like that for over 4 years, I never thought cheap PC fans would last this long but they are just as quiet as when I put them in.

It seems to be a very effective solution, I have one at the bottom of the wall for intake that blows clean cool air right over the servers, and one at the top of the room kicking the warm air back into the outside room. If I turn the fans off I see the temp rise quickly, so it really works.

Cheers

Cris.