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Old 10-15-2013, 09:34 PM   #11
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I have another little power supply with all of the same specs but it's .3A. I assume this will work? I'd test it now but I'm at work I'll have to wait until I get home.

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Old 10-15-2013, 10:10 PM   #12
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Yes, that should do it.

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Old 10-15-2013, 10:32 PM   #13
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DC power supply, AC fan

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Old 10-15-2013, 10:33 PM   #14
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Quote:
Originally Posted by Setesh View Post
That fan is rated for .24A. So that power supply isn't capable of fully powering that fan. Do you have an old wireless router or any other 12 volt power supplies laying around? That is what I use for mine. It provides 12V at 1.2A and works great. To test and see what the fan can really do you can hook it up to a computer. It will get the full voltage and amperage it wants then and you can compare that to what you get out of your little power supply.
Sorry for the ignorance, I'm trying to learn more about this stuff, but I'm pretty much a total noob.

How do you know the fan is rated for .24A? I don't see the amps listed in the link for the fan?

Also, can you breify explain which value you compare the fan's amps to on the power supply? I suppose it's the DC output current of the power supply, but I'm not 100% sure.
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Old 10-16-2013, 12:21 AM   #15
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Quote:
Originally Posted by Pie_Man View Post
Sorry for the ignorance, I'm trying to learn more about this stuff, but I'm pretty much a total noob.

How do you know the fan is rated for .24A? I don't see the amps listed in the link for the fan?

Also, can you breify explain which value you compare the fan's amps to on the power supply? I suppose it's the DC output current of the power supply, but I'm not 100% sure.
No need to apologize. We are all ignorant in some areas and knowledgeable in others. That's why this and other forums are so effective.

The picture in your link shows the sticker off the back of the motor housing that I referenced earlier. It states the input voltage (12) and amperage (.24). Your power supply should be rated with the same number of volts and at least the same number of amps as your load. Your fan wants 12 volts to run, but it needs .24amps to get that voltage. Your power supply isn't capable of dishing that out. If you replace your current power supply with a 12v 1amp power supply your fan will take the 12 volts it wants at .24 amps. It will only take as many amps as it needs to get it's voltage. It's kind of hard to explain, but basically amperage is the force that pushes voltage through a load. You can have a power supply that is capable of more amps than necessary and it will not cause any problems. However this is NOT true of volts. Push too many volts through a load that isn't rated for it and the magic blue smoke will escape. Electrical devices run on magic blue smoke. Once the magic blue smoke escapes the device will never work again.
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Old 10-16-2013, 12:33 AM   #16
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That power supply should be enough--the output rating at 12V is 500mA (0.5A). The fan requires 0.24A at 12V. But, as DaleHair asked, is the fan AC? If so, no amount of DC current is going to work. You'll need an AC power supply.

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Old 10-16-2013, 12:40 AM   #17
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That power supply should be enough--the output rating at 12V is 500mA (0.5A). The fan requires 0.24A at 12V. But, as another poster asked, is the fan AC? If so, no amount of DC current is going to work. You'll need an AC power supply.

MaxStout is correct. I missread your initial post. I thought .2amps was your power supplies output. The fan wants 240ma (.24amp) which is < the 500ma (.50amp) that the power supply should put out so it should work just fine.
The fan he linked is a cooler master 80mm computer case fan and runs off of DC voltage. It should spin at ~1700 RPM which shouldn't feel anemic to you. They are not powerful fans by any means, but running free air they certainly spin fast.
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Old 10-16-2013, 12:44 AM   #18
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Thank you both, I still learned something. I'm not the OP, just someone trying to learn from their misfortune

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Old 10-16-2013, 12:50 AM   #19
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OK, looks like the fan is DC (I looked at the linked spec). Try bypassing that rheostat so that you're connected at full voltage. Does it spin OK? The spec stated the fan's voltage range of 10.8-13.3V. That's a pretty narrow range (most 12V computer fans I've seen work well down to 5 or 6V), but maybe that particular fan doesn't work well below 10.8V

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Old 10-16-2013, 12:57 AM   #20
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The fan manufacturer spec's indicate 12vdc & 0.96w which calculates out to an 80mA current draw and about 150ohms of dc resistance. Not sure where the 240mA came from. A 500mA 12vdc power supply should spin it fine.

Do you have a multimeter to measure the voltage being applied to the fan? The rheostat may be wired incorrectly. Is it in series or parallel to the fan? It should be in series.

Theoretically, with the rheostat in series, you should have 10v to 12v to the fan for the 25 to 0 ohm swing of the rheostat. 10v may not produce a noticeable reduction of the rpm as compared to the 12v rpm.

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