has anyone used a fan on their project?

[jarthel]

I may have a need to use a fan in my project. The tubes (2x 8cg7 running at 8V heaters and 2x 6H30 running at 6V heaters) are inside the chassis.

I plan to get the power from the 1st cap of the regulated DC supply (using LT1084 which is similar to LM317) which acts as heater suppy for the tubes mentioned above.

not sure what fan size to use yet. But I'm hoping I can fit a low noise 8cm fan in there. I may need to install the fan on the outside of the chassis which thankfully is on the back. I'll need to see if it fits.

Should the fan be blowing in or out?

any thoughts/comments?

thank you.

[Eli Duttman]

Buy a low cost device that steps "240" V. down to "120" V. You use a "240" V. fan with 120 V. The fan turns slowly and makes less noise.

[jarthel]

Originally posted by Eli Duttman
Buy a low cost device that steps "240" V. down to "120" V. You use a "240" V. fan with 120 V. The fan turns slowly and makes less noise.

the low noise fan I'm talking about produces 26cfm at 21dB. so it's not loud at all. PLUS it only costs $15 AUD including shipping.

I somehow think that you're low cost device + fan would be more expensive than $15 AUD.

[Sonusthree]

Originally posted by jarthel
Should the fan be blowing in or out?

I seem to remember from researching computer case cooling that pulling air out of a chassis is much more efficient. This is probably more important for a smaller chassis.

[Sheldon]

The key to efficient cooling is to get the highest flow aroung the parts generating the most heat. This is generally easier to do by blowing in, as you can direct the flow by pointing the fan at the heat sources.

I'm with Eli on the voltage issue. Noise is a function of blade design and blade speed. Start with a quiet design, use a larger fan, run it at lower speed (voltage).

Sheldon

[Tweeker]

Blow in, with a filter. Think about dust. Other methods might be more efficient, but dust is a bigger deal here than in computers.

[Tweeker]

Im not sure just how Chicken Little I am here, but...

Its possible the fan motor may contaminate the heater rail, 3 pin regs dont do as well with this noise as they do the ripple.

[zigzagflux]

Blowing out is better, as you do not push heat around inside the cabinet, you push it out. That's why all computer power supplies blow out. Of course, they also have the luxury of mounting the heat sources NEAR the fan, so this method works well.

If your heat source is not very close to the fan, you will need to resort to blowing in.

I looked into 120/240 fans for my amp, and couldn't find anything small enough to bury inside the chassis. AC would definitely be the way to go, if it fits.

[jarthel]

why AC?

Also, I looked at the locally available AC fans and they have lower CFM rating that the DC fan I'm looking at. PLUS they are much noisier.

so again, why AC? maybe AC fans in the US have much better specs?

ps. please note the max I can fit is a 8cm fan.

[jarthel]

Originally posted by Tweeker
Im not sure just how Chicken Little I am here, but...

Its possible the fan motor may contaminate the heater rail, 3 pin regs dont do as well with this noise as they do the ripple.

that is the reason why I mentioned it. hoping someone would give advice