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Re: Need DC Power supply help
> Date: Sat, 27 Jan 2001 22:14:45 -0600
> From: Rod Hanks <rhanks at benchbuilt_com>
>
> ...night-light. Used a 12VDC 500mA power supply he bought
> someplace for less than $5. Clearly, he was not shopping at
> RadioShack. I hear all the time of people using PC cooling
> fans. These fans are small and quiet, but they generally take
> 3VDC or 12VDC power, and I don't know how to supply them.
>
> Somebody have mercy and clue me in on where I can buy
> a power supply that runs on 120VAC, outputs 12VDC with
> enough amps to run a small fan, does not use a lot of power,
> and doesn't get very hot. Part numbers would be nice.
> I'd be grateful.
>
Jameco electronics, part number 114825. 12VDC, 500ma:
http://www.jameco.com/cgi-bin/ncommerce3/ProductDisplay?prmenbr=91&prrfnbr=2973&cgrfnbr=501
The Jameco catalog has 3 pages of fans; there is a 4" 115VAC fan that is
sound rated at 15dB that look interesting.
I think you could probably get your existing 115VAC fan to work quietly
by putting a small wire-wound power resistor in series with it (on the
"hot" wire, not the neutral). You would have to experiment to figure
out the resistance, but you could experiment with cheap carbon-film
resistors until you get it right, then replace with an equivalent proper
power resistor. I also just might try using a low-ohms potentiometer,
wired as a rheostat, to see if it would work (jameco part # 140513, 5W
linear taper wirewound pot):
http://www.jameco.com/cgi-bin/ncommerce3/ExecMacro/Jameco/searchResult.d2w/report?sort=&search=pw5b100
HTH, bob
"A stairway to oblivion is better than no stairway at all"
--Kehlog Albran