From: firstname.lastname@example.org (N. Thornton)
Subject: Re: Quieting all these fan motors
Date: 14 Sep 2002 13:37:01 -0700
NNTP-Posting-Date: 14 Sep 2002 20:37:01 GMT
"George Gonzalez" wrote in message news:...
> I'd like to be able to have the fan speeds proportionally controlled,
> not just ON/OFF. I suspect having fans cycling ON/OFF randomly every few
> seconds to minutes would not be almost as bad for my equilibrium, (and the
> equipment's) as having them ON all the time.
> Plus it would be nice if this could be done with just a thermistor. I know
> it can be done, your newer, typical, just slightly better than dirt $39.95
> PC power supply often has a 12V motor and a thermistor for speed control.
> Another question is exactly *where* to place the thermistor for "best"
> temperature control. Probably near the hottest component, which usually is
> the power supply pass transistor. If I can ensure there always is some air
> flow, measuring the outgoing air temperature might also be a good place.
Don't try John Fields well meaning suggestion. The cooling fan will
not only be for exhausting the case, but will probably cool a heatsink
or 2 or 3 directly. In other words, if you monitor internal case temp,
and wait for it to warm up, your power devices will be dead by the
time the fan comes on.
Bearing that in mind, you would need to monitor the temp on each
heatsink in the air path _as well_ as the internal case temp. To put
it another way, get used to switching yout kit off every minute you're
not using it, because fan speed control wont be as simple as you
How did they reduce noise back then? Mainly by add on mechanical
Baffle boxes were sold that attached to the back over the fan outlet.
They are basically a wooden box lined with thick carpet, with a
straight thru the box airpath. Just attach externally.
Second, remove the fans and reattach them using rubber mountings. That
Third auto underseal the indside of the cases, or polystyrene foam
where safe,m etc.
Fourthly build a cabinet the equipment sits in. Cabinet walls are all
covered with thick carpet, and put thick carpet on the wall behind the
cab where the warm air is exhausted.
Its crude, but its how it was done, and with enough effort it makes a
There is one final option... remove all powe4r components and replace
with much higer power ones plus much bigger heatsinks. Replace covers
with expanded metal covers. Then no fans needed. But its extreme.