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Powering a 24vdc fan??

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Korndog

Member
Joined
Nov 30, 2002
Location
California
hey guys
i just got a 24vdc blower, its really sweet
even though its running at 12v, it blows a lot of air, but with my filters and radiator, its kinda not strong enough so i need to run it on 24vdc.
i found some big 24VAC transformers that i have, obviously those wouldn't work. I remember learning from my physics class that Diodes change AC to DC (don't ask me how, i'm totally clueless with electronics, lol) I have a few Diodes a Germanium 1N60/HP80 and two Silicon 1SS53/1N4148. does any know what that means?? i really dont' have the guts to test it out.., remember the last time i played around with a diode, it turned red and blew up :-/

thanks guys :)
 

L337 M33P

Member
Joined
Jun 5, 2003
Location
TEH INTERNETS
Nope. They are small signal diodes, not rectifiers. The 1N4148 for example has a maximum current of 0.1A so plugging it into a motor = crispy. Fear not, just buy a diode bridge for like 40 pence.
 

cstarritt

Member
Joined
Nov 7, 2003
http://www.surpluscenter.com/item.asp?UID=2003121602201963&item=15-1159&catname=electric

thats one option, with a little wiring and a relay, you would hook it up so that when you mobo sends a signal up the "ps on" line to turn on the ps, it kicks the fan on.



also, another thing you might be able to do is hook into your ATX connector's -12v and +12v lines and use that to get 24v off your ps. be warned though, most ps are not rated for much juice on the -12 rail. mine is rated for one amp. you would need to find out how much of that 1 amp your mobo uses, or use a second ps you got laying around. i tried it with a unused ps that i hotwired to turn on not pluged into a mobo with a 24v blower i have and it works great. you can also use the +12 and -5 lines for a 17v "medium" setting if the 24v is a bit too loud.
 

Hoot

Inactive Moderator
Joined
Feb 13, 2001
Location
Twin Cities
If you want to keep everyting internal to the PC, consider scouring the surplus sites for a DC-DC convertor, either a 12V to 24V or a 5V to 24V. Otherwise, you're stuck with that 24VAC transformer, some rectifiers or a bridge array and a capacitor. Keep in mind the a full wave bridge rectifier will yield a final DC voltage up around 30-something volts when you start at 24VAC. To get 24VDC, you'd want to start with something like an 18VAC transformer. Depending upon how much current that 24VDC fan draws, you may be able to use the -12V rail. I got one of those Torin 24VDC squirrel cage blowers. It's rated at 14 watts @ 24V. That equates to about .6 Amps. You system may not mind that load on the -12V, but who's to say. You just try it and see what happens. My setup, using an Antec True550 didn't even blink when I used the -12V rail as the return on the Torin fan, but I can't say how a different PSU would respond.

Hoot