From: John Woodgate
Subject: Re: 12V computer fans run from 27 to 38V, speeding up at high temperature
Date: Tue, 22 Oct 2002 09:58:16 +0100
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Tue, 22 Oct 2002 09:27:38 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Winfield Hill
wrote (in ) about '12V computer fans run
from 27 to 38V, speeding up at high temperature', on Mon, 21 Oct 2002:
>>-Thinking kindly on the hungry masses here at s.e.d., here's a bone
>> for yo'all to knaw on. I'd like to run various generic 12V computer
>> heat-sink fans from a 27 to 38V supply, using a PWM buck regulator.
>> The fan should run slowly at room temp, but increase to full speed
>> by ~ 40C heat-sink temperature. Full speed would be 12V fan drive,
>> which shouldn't be exceeded even if the temperature rises over 40C.
>> I have faith that s.e.d. engineers can find a good solution, while
>> I sleep peacefully, awaiting the results of your feverish efforts.
> Pardon the patronizing, insolent tone of the above posting, but
> 171 messages on the subject, "How does a mixer work?" Sheesh,
> all you fellows need something to get your teeth into!
As I already posted, the question of the 'reality' of sidebands, and
similar questions, are as old as radio, and it seems each generation has
to learn all over again. The present discussion shows that more and more
sophisticated tools are randomly thrown at the questions, resulting in
more and more confusion instead of enlightenment.
An identity is an equation in which the LHS is always, everywhere and
exactly equal to the RHS. But what is 'true' for the RHS is NOT
necessarily 'true' for the LHS. For example, one side has three discrete
terms, the other has only one.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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