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Fan speed mod help


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I have an intake fan that moves 105cfm through a grill and puts out about 44db. as you can imagine that is fairly annoying. It is connected to a molex connector. I know I can mod it to run on 7v but I think that will reduce the cfm too much to keep my system cool. is there a way to get it to run on 10v? like maybe with a resistor or something?

Edited by Savan

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You could try 8.7V, fan Ov to 3V3.

 

If you want to use a resistor then it's trail and error really it depends on fan types. Start at something like 18 ohm and work up, 22 ohm, 27 ohm, 33 ohm, etc., until it's to your liking. Perhaps a 47 ohm potentiometer to give you a little variabilty.

 

You could also use diodes, something like the 1N4004, in series each diode will drop approximately 0.6V.

 

All these components are a few pence each so it's worth a try.

 

Cheers

 

Paul

Edited by paulktreg

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thanks Ill give it a try. it doesn't matter which wire I put these on because it DC correct? (its only a 2 wire fan)

 

It doesn't matter no but it's good practice to put them in the red positive wire.

 

Cheers

 

Paul

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I've had a lot of luck with diodes.... they can take a lot more current for the size... I've even made a rotary fan control using a cascaded arrangement of 3A diodes on a rotary switch, to handle banks of high power fans.

 

I'm not sure a (regular) potentiometer could handle a fan like yours Savan... I'm guessing it's something like a 12V 0.4+A fan?

 

You'd have to ask Paul about 5W pots... all the ones I found were really expensive

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