On Sun, 2009-09-27 at 15:31 -0400, Martin Ewing wrote:
> I agree that the fan is too loud. I have lived with it for a long time, but
> now you're making me think that action may be required!
> You could take Tony's approach, but another way to do it would be to put a
> resistor in series with the fan. That would limit its maximum speed (noise
> is a rapidly increasing function of rpm). The cooling would be less, and
> the thermal switch would stay "on" for a greater percentage of the time, but
> the noise would be less.
> You could also bypass the thermal switch and let the fan run continuously,
> but more slowly. You'd have to satisfy yourself that the PS is cool enough
> under max. load and at max. ambient temperature. You might replace the fan
> with a slower, quieter model if you ran it continuously.
> The on-off "bang bang" temperature controller is cheap, but rather crude. A
> proportional controller that adjusts rpm smoothly would be a lot friendlier
> - similar to what you get with some computer systems.
> 73 Martin AA6E
> On Sun, Sep 27, 2009 at 8:25 AM, Tony Berg <firstname.lastname@example.org> wrote:
Fans are made noisy and are made quiet. Noise can be bearings or wind.
Bearing noise indicates a need for lubrication. Usually its right
through the middle of the label on a muffin fan. Cut an X with a sharp
knife and inject a bit of sewing machine oil.
Alternatively measure the fan dimensions and see if you can find its air
flow rating, then go to a major distributor like Mouser (www.mouser.com)
and browse their selection of muffin fans for a fan with the same
voltage rating, same size, but a quieter noise rating. The quietest
muffin fans have serrated trailing edges on the blades. A lot like a
bird's wing feathers. New small fans are not expensive and Mouser is a
good place to deal with.
73, Jerry, K0CQ
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