Help wiring these fans

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Old 11-04-09, 07:36 PM
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Help wiring these fans

Hi,

I'm wiring a couple of 12v DC computer case for a DIY project:

Masscool

My questions are:

- I'm planning on powering them with a 5V 1A power supply

- the fans says they have a "current" of 0.15 amps.

does that mean I can supply 6 fans (0.15 x 6 = .9 amps)?

what if I were to use the 5V power supply for just 2 fans, would they run faster if I supply them with more power? Or are they limited to 0.15 amps of input?

I have several DC power supplies lying around and want to power up to 10 fans.


Any help would be much appreciated!
 
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Old 11-04-09, 07:50 PM
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a motor draws what it does. A dc motor's speed is affected by voltage but over driving one with above rated voltage is often a good way to smoke the motor. Using that power supply to drive fewer motors will not make the fans run any differently. The voltage output will remain the same.



by the numbers, yes, you could operate 6 fans on the power supply. I would be hesitant to run it that close to the limit though. Those tolerance allowances could more than use of the .1 amp you think you have.

Whoah!! I just looked at the link. Those are 12v fans. You need a 12 volt power supply,
 
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Old 11-04-09, 08:37 PM
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thanks for the feedback

1 - good to know it wont matter if i "overdrive" themwith power

2 - right, good point about running it so close to the limit

3 - wow, totally missed that but yes, they're 12 v fans. i actually thought it didnt matter if i used 3, 4, 5, 6, 9, etc volts to power them. i've tested it and each of my power supplies runs the fans.

so what's the result of not using 12v? will they not run at full speed? i tried runnining one fan with 3v and one with a 6v supply and didnt really notice a difference. i figured, hmmm, it all depends on the amps being taken in?
 
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Old 11-04-09, 08:48 PM
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with a dc motor, lower voltage means lower speed but that will also affect the current draw.
 
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Old 11-05-09, 08:07 AM
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Originally Posted by nap View Post
with a dc motor, lower voltage means lower speed but that will also affect the current draw.
Ah! So I'm best just getting a 12V power supply to make sure I have the correct voltage. Maybe that can be used to power 6 fans at the same time?
 
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Old 11-05-09, 08:17 AM
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If you do use the wrong power supply it could either burn up the fams or the power supply which in turn could start a fire. Make sure your + & - are hooked up correct also.
Jim

 
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Old 11-05-09, 08:25 AM
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Yikes. Thanks, this is the area I have most trouble with.

THis is great advice.

Ok, was thinking of using something like this to power the fans.


Newegg.com - OKGEAR PA-AD-UL 12V/5V AC/DC Power adapter w/ 4pin molex connector - Adapters & Gender Changers
 
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Old 11-05-09, 11:15 AM
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I jsut found this online about the fans - cant beleive I missed this before:

approximate fan speed varied by voltage:
6V = 1325 RPM
7V = 1575 RPM
8V = 1800 RPM
9V = 2000 RPM
10V = 2175 RPM
11V = 2400 RPM
12V = 2600 RPM

So there it is. I will get a 12V adaptor above and run 6 or so of these fans.

Thanks!
 
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Old 11-05-09, 07:04 PM
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Most wall wart power supplies are not voltage regulated so their output voltage will change inversely to the current load. A 1 ampere 12 volt supply will output much more than 12 volts if the load is only 0.1 amperes, probably 15 volts or maybe even more.
 
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