[geeks] good source of cooling fans (for computers)

[Charles Shannon Hendrix]

On Tue, 20 Feb 2007 22:07:46 -0500 (EST)
der Mouse <mouse at Rodents.Montreal.QC.CA> wrote:

> > I'm having a hard time finding a good quality replacement that
> > matches the specifications:
> 
> > 12V 0.52A
> > 1200-2400 rpm (power supply controls speed)
> 
> *How* does the power supply control the speed?

It varies fan speed based on its own power consumption.  It's not a
temperature controlled fan if that's why you are asking.

> > I can find a ton of 120mm fans, but either they don't support that
> > much power, or the seller doesn't give the specs on the fan.
> 
> I don't see how a fan can "support that much power" or not.  I've never
> yet seen a case where something will break if a fan draws .15A at 12V
> instead of .52A at 12V.  

That's the opposite of my concern.

Higher rpm fans have a higher amp rating, and I need a high rpm fan
(relatively speaking).

An 800rpm fan seems to be around 0.1A, while a 3000rpm fan seems to be around
0.60A.  That's for 120mm 7 blade designs.

I wasn't sure how the power supply changes the fan speed, so I want to
get as close to the original part's specifications as possible.

Also, the way I understand it, good fans have a current limiter to set their
maximum speed.  If I don't get a 0.52A fan, it won't run fast enough.

For all I know, the lower amp fans also use smaller guage wiring inside and
don't dissipate heat as well.

> Have you considered taking a fan that draws less current and sticking a
> resistor in parallel with it?

No.

I want a drop-in replacement.



-- 
shannon           | Consulting wouldn't be what it is today without Microsoft 
                  | Windows.
                  |        -- Chris Pinkham