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Old 07-03-2012, 12:21 PM
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Default Powering old CPU fans.

I have an old CPU fan that I am going to use to ventilate my new viv. I have the fan all set up and ready to go, but I am having problems findings a power supply. It needs a 12v 0.15a power supply. 12v isn't hard, but finding such a low amperage is becoming a challenge. Where do you guys get your power supplies?

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Old 07-03-2012, 12:51 PM
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Default Re: Powering old CPU fans.

You should be able to use that fan with any 12v power supply regardless of the current rating. The current is more of a maximum rating for the power supply, so you can hook up a bunch of 12v devices as long as the cumulative current demand is less than the PSU current rating. This is because the internal resistance of the fan and voltage across the fan determines what the current flow ultimately is. voltage = current * resistance. Most PSUs supply constant voltage and the resistance of the fan never really changes so the current draw of that fan never really changes. There are some constant current PSUs, mostly for use with LEDs, that you don't want to use. You want the run of the mill constant voltage, AC/DC power supply. Look for one that is 12v with probably about a 1A current rating. This should work for your single fan but also has the capacity to run additional 12v devices in parallel up to a maximum total current draw of 1A.

Does that make sense? It's been awhile since I took electrical physics so hopefully that's coherent.


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Old 07-03-2012, 02:16 PM
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Default Re: Powering old CPU fans.

I just wire them to an old phone charger that is 12v. I've never had (so far) any overheating with them etc.
Lots of Tincs, Black Capira, Inferlanis, Cits, SI's, Terribilis, this and that.
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Old 07-03-2012, 04:53 PM
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Default Re: Powering old CPU fans.

right, as long as the fan does not draw more power than the wall wart requires, you will be fine. example: you have a 12v DC that handles 1 amp, you could hook up 5 of those fans safetly to it. there is a general rule that your power supply should be able to handle 10% more power that you are asking from it.
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Old 07-03-2012, 11:29 PM
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Default Re: Powering old CPU fans.

Cool! Thanks for the replies everyone!!
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Old 07-04-2012, 10:18 AM
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Coolerguys.com. Great seller, good prices. They have a bunch of fans, controllers, and even temp probe controllers. Got to me in 2-3 days.
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