David Jenkins
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| posted on 18/5/08 at 09:04 AM |
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PC fan connection
This is VAGUELY car-related, as it's to do with a little fan I bought in Maplins to go into the case for my JAW AFR meter... 
This little 5-volt fan was intended for use in a PC (laptop or similar), but it has 3 wires coming out of it - black, red, and yellow. As there
aren't any split 5v supplies in a PC I was wondering which wires to use.
Anyone know the answer?
David
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Peteff
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| posted on 18/5/08 at 09:15 AM |
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It's 12v or 5v by the sound of it
Yellow 12v+
red 5v +
black 0v - or earth
Try the yellow and black across your battery in the right order or it will spin backwards.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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BenB
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| posted on 18/5/08 at 09:18 AM |
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I don't reckon that's right!!!
I reckon its
Red 12v
Yellow tacho
Black ground
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RazMan
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| posted on 18/5/08 at 09:19 AM |
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You might have a speed sensor on the fan but normally black=gnd, yellow=+ve
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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BenB
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| posted on 18/5/08 at 09:20 AM |
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http://www.pcguide.com/vb/archive/index.php/t-19457.html
There we go 
From the PC power supply its Yellow=12, Red=5v, Black=Gnd
but on the fan its Red/Black = Power/Gnd
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Peteff
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| posted on 18/5/08 at 09:23 AM |
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If you ground the red it's 5 volt if you ground the black it's 12v according to that then?
[Edited on 18/5/08 by Peteff]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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BenB
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| posted on 18/5/08 at 09:24 AM |
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Not all PCs fans have the tacho function and when they don't it's the yellow wire that's missing.... QED
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Peteff
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| posted on 18/5/08 at 09:28 AM |
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And not all PC fans are 12v, some are only 5v usually the ones which plug into the board not into the PSU.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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dhutch
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| posted on 18/5/08 at 10:08 AM |
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quote:
Originally posted by BenB
I don't reckon that's right!!!
I reckon its
Red 12v
Yellow tacho
Black ground
Thats what all the dosens of fans ive had have been. Somtimes the tacho is white, and -ve blue also.
- Ive not realy seen any 5v fans in PCs eather, although they proberbly do exist, an there is 5v avilable in a pc.
You standard molex (4pin) plug in a desktop is Yellow=12v, Red=5v, Blk=Grn.
So i would suggest you want to wire Red to Red, black to black, and leave off the yellow.
- For a 12v fan, Red to yellow, Black to black, leave off fans yellow.
Another related trick is to get a 12v fan and wire it between the +12 and +5 rails t get 7v. Tends to be enough to keep most things cool, but is
quiter than 12v!
Daniel
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Peteff
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| posted on 18/5/08 at 10:51 AM |
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The 5v ones I have are from an old pentium pro system so they probably don't exist any more. There's a site here telling how to run your
fan as a 7v as well link
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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David Jenkins
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| posted on 18/5/08 at 05:20 PM |
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It is 5v, according to the label, at 80mA.
I've tried it across the red and black wires and it runs very nicely, so thanks to all.
I forgot to mention just how small this thing is - it doesn't shift a lot of air (understandably) but all I want it to do is to move air across a
voltage regulator heatsink.
 
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carpmart
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| posted on 19/5/08 at 07:37 AM |
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It may be small but its still adds weight! 
You only live once - make the most of it!
Radical Clubsport, Kwaker motor
'94 MX5 MK1, 1.8
F10 M5 - 600bhp Daily Hack
Range Rover Sport - Wife's Car
Mercedes A class - Son's Car
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