12v DC fan problem

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AndrewB
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Post by AndrewB » 09/28/03, 8:45 am

I recently bought a 12v DC fan (120MM) for my case, as I want to make a blowhole to remove excess heat. This model was relitavely cheap because it does not have any kind of plug, only two raw wires. I tried to make this work by connecting the red and black wires to like colored wires on a female power connector which had the male end cut off. Aparently not enough power is transfered this way, as the fan will not work at all and a very small peltier I have does work on the same connector.

What kind of setup am I going to have to have to make this work? Gracias.
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Post by SOD » 09/28/03, 9:23 am

Is the fan good?

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Post by SloppyGoat » 09/28/03, 9:46 am

You want to use the yellow and black wires, if you're using a IDE molex connector. Red is low voltage...not 12V.

See. Any 12V fan connector has the wires connected to the yellow and black side. Red to yellow and black to black.

http://www.dansdata.com/images/viperfan/320/wire.JPG

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http://www.xpcgear.com/ockit.html

<font class=editedby>[ This Message was edited by: SloppyGoat on 2003-09-28 18:08 ]</font>

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Post by Gerry » 09/29/03, 2:26 am

That looks hell sweet Sloppy. I'm just about to install a new fan, the one I'm using atm is hell noisy, maybe I'll look into an air duct while I'm at it... not that I need it, it just looks cool.
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Post by SloppyGoat » 09/29/03, 9:55 am

Fresh, filtered, cool air from outside the case has to be the best air cooling there is, IMO. It would also be a hell of alot easier to clean the filter than the fan and HS. That would solve any case heat problems. All you need is a 60mm to 80MM adapter, since it's for 80mm fans. I'm thinking my old FOP38 heat sink would be perfect for the conversion. I don't know....I might go with copper, though.

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Post by AndrewB » 09/29/03, 1:13 pm

my site has a ducting guide if you need pointers. Also, I connected the red to yellow and it works now. Thanks sloppy. now all I have to do is find a resistor that will lower the fan speed so that I get something less than 108 CFM!
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Post by SloppyGoat » 09/30/03, 9:35 am

<!-- BBCode Quote Start --><TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font class=postbody>Quote:</font><HR width=100% color=#333333 SIZE=1></TD></TR><TR><TD><FONT class=quote><BLOCKQUOTE>
On 2003-09-29 21:13, AndrewB wrote:
now all I have to do is find a resistor that will lower the fan speed so that I get something less than 108 CFM!</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR width=100% color=#333333 SIZE=1></TD></TR></TABLE><!-- BBCode Quote End -->
What the hell kind of fan is that??? :o
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Post by AndrewB » 09/30/03, 4:35 pm

A bigass 120mm one! its probably about 3-3.5 in in width ; It was only about 10 bucks @ Fry's Electronics.
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Post by AndrewB » 09/30/03, 4:35 pm

Correction: 12.99
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Post by SloppyGoat » 10/02/03, 6:56 am

I was gonna say...that's gotta be either big or fast or both to put out 108CFM.

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Post by AndrewB » 10/02/03, 9:48 am

Yeah. If I can't easily solve the resistor issue I'll just get a *much* less powerful model and in exchange for the current one. With at most 60CFM coming in and probably 35-45CFM going out as it is, 108CFM will surely cause problems.
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Post by SloppyGoat » 10/02/03, 1:46 pm

Just get a bunch of resistors and try a few. Any resistor on either wire will slow it down. It's just a matter of finding the right value. An easy way to do it would be to use a pot to select the speed you want, then measure the resistance of the pot at that setting. Or just use the pot instead.

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Post by SOD » 10/02/03, 4:59 pm

Andrew, why would you want to slow the fan speed?
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Post by SloppyGoat » 10/03/03, 3:08 am

SOD, think about how loud a 38CFM fan is, much less a 108CFM! Besides, that thing would just turn his case into a vacuum cleaner. :lol:
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Post by Don » 10/03/03, 5:34 am

If you put a normal resistor in-line wouldn't it just replace fan noise with hum as the increased current makes the motor heat-up and labor at the incorrect voltage?   I found that is exactly what happened with our 10" bathroom fan with a cheapo light-dimmer attached so that I didn't freeze in the shower.   :-)   That is AC of course, but won't a DC motor react the same and be more likely to burn-out because of the increased current?   Also wouldn't you need at least a 10 watt ceramic resistor to do the job if it is possible?

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