Fan Speed Reduction Cable

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cbr

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cbr

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Ok going to try keep this short....

http://www.overclockers.co.uk/showproduct.php?prodid=FG-006-GE

Are these ok/safe for 24/7 use ? !! Important !!

Reason I ask...
I was going to just buy some resistor's and do it myself, need 4 -5 cables.
BUT read that if I get the values wrong, I.E wrong resistor's to match the fans I could have a melt down or fire :eek: that put me off.

Then I wondered how akasa seem to have made the above cable that seems to suit any fan ?

Any help/advice would be great ;)
 
That cable appears to have three components within the heat-shrink. I'd guess that it's three diodes in series which would give you a drop of roughly 2V irrespective of the fan connected.

If you want to do it with a resistor then a you'd need to apply a bit of Ohms Law to get the values you need (and then pick something that’s similar). If you get it very wrong you’ll either see virtually no difference, or the fan won’t spin at all. I can’t see any way that you could actually manage to melt anything, the currents involved just aren't that high.

FWIW the three dropper cables I have to hand are 5 Ohms (from an old 2U rack mount with high current fans) and 50 Ohms & 80 Ohms (from a Noctua NH-D14 with its fairly gentle 120mm/140mm fans).
 
If the info is any use your P8Z68 has the ability to slow down 3pin fans through the Q-Fan settings in the BIOS (only the chassis fan headers support voltage control not the CPU fan headers IIRC, been a while since I used that board).
 
I have home made fan resistor cables on the top two 140MM fans in my case, my system is on 24/7. Never had any issues :)
 
If you want to go with Akasa's diode method you'll need something like 1N4001. Using diodes takes a lot of the guesswork out of things as they will drop 0.6v-0.7v per diode. It will be easier than messing with different resistors. 1N4001 are good for 50v and 1A.
 
Well thats cleared it up for me, akasa use diode's not risistor's.
Diodes seem to be the way to go for the job I want.

Thanks to everyone for the input.
@ ubersonic, your right about the MB fan control im using it, but this mod/fans not for pc, but did'nt want to get into that part lol

@ Tealc cheers for the tech info (1N4001)
Presume that will be good for just about any pc / 12volt fan.
 
With the resistors they may get hot over time and the resistance may increase. With diodes they only allow a certain current through untill you break them (too much current) they they don't provide any resistance.
 
Do many fans draw much over ? 1N4001 are good for 50v and 1A

hoping im right in the thought if I dont connect a fan that draws over 1amp, im good for 24/7 running ?

Just one last thing,, using the above diode (maybe 2-3), will the header its plugged into have any more (or less) strain ?
As I have no info on what this header is good to give

Found some local
1N4001s
1N4001g
not sure what the letter means
 
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cbr said:
Do many fans draw much over ? 1N4001 are good for 50v and 1A

hoping im right in the thought if I dont connect a fan that draws over 1amp, im good for 24/7 running ?

Just one last thing,, using the above diode (maybe 2-3), will the header its plugged into have any more (or less) strain ?
As I have no info on what this header is good to give
Click to expand...

As long as you don't exceed the current rating of the diode you'll be fine. In the unlikely event that 1A isn't enough use a different diode.

Are you aware that you'll need to fit the diodes the correct way around?
 
yes bremen know that part cheers

Found some local
1N4001s
1N4001g
not sure what the letter means though...
 
cbr said:
yes bremen know that part cheers

Found some local
1N4001s
1N4001g
not sure what the letter means though...
Click to expand...

It doesn't matter. The G ones have a glass passivated junction. Not sure what that is as I've never needed it but it's certainly unimportant for this application as all you want is the voltage drop.

1 Amp is a good for a whole lot of fans. 50V is 4x enough to cope with a PSUs output. It's why I recommended it. They are cheap, available and aren't too cumbersome to fit inline on a cable. If you want to be really clever you can use a switch (with suitable rating) to switch on and off diodes to act as a simple fan controller.

Just make sure you fit them the right way around. ;) The diodes will have a grey band at one end. Make sure that's near the fan end of the cable, that goes for all of them. If you wire even one backwards you'll get no current flow at all.



As for resistors, if you want to explore that, one way to estimate the resistance needed is to calculate what resistor you'd need for each fan.
Luckily there's a handy calculator available.

http://www.blackfiveservices.co.uk/fanspeed.shtml

Of course the current rating on fans is often incorrect so this doesn't make it all that accurate, unless you can measure current with a multimeter on each fan yourself.


And as for the safety of running resistors.... provided you fit the right value resistors and they are rated high enough to cope with the current draw of the fan they'll run for decades. Resistance will change slightly with temperature but it won't be an issue as fans are not a precision application.
 
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