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How to convert 120v AC to 12v DC?

Old 10-12-11, 05:26 PM
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How to convert 120v AC to 12v DC?

I have some old computer (4 total) fans that I want to power up to cool off my components. Is there a way (or a box) that I can plug into the wall to power 12v items?

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Old 10-12-11, 07:06 PM
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Re: How to convert 120v AC to 12v DC?

Just get a 12 volt power brick like Radio Shack used to sell, or even a 12 volt car battery charger (although those might put out more like 14 volts which still should be ok).
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Old 10-12-11, 07:47 PM
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Re: How to convert 120v AC to 12v DC?

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Old 10-12-11, 07:55 PM
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Re: How to convert 120v AC to 12v DC?

X...I did some more poking around on the internet and many people (trying to do the same thing as me) take an old cell 5v cell phone charger and snip the plug off the end, strip the wires, and hook up the fan. I tried it out and it worked perfectly!

Now what I'm not sure of is how many fans would one 12v phone charger power? It says 12v and 1000mA

and here are the stats fo rmy fans:
Rated Voltage: 12VDC
Rated Current: 0.08+/-10%A
Power Input: 0.96W

Last edited by namrfumot; 10-12-11 at 08:06 PM.
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Old 10-12-11, 07:57 PM
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Re: How to convert 120v AC to 12v DC?

P = V * A

5V * .550A = 2.75 Watts

So two fans.
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Old 10-12-11, 08:14 PM
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Re: How to convert 120v AC to 12v DC?

Originally Posted by Shazam View Post
P = V * A

5V * .550A = 2.75 Watts

So two fans.
so if I went on Flea-Bay and bought a cheapy adapter thats 12v and 2000mA that's be 24 watts?
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Old 10-12-11, 08:15 PM
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Re: How to convert 120v AC to 12v DC?

Originally Posted by namrfumot View Post
X...I did some more poking around on the internet and many people (trying to do the same thing as me) take an old cell 5v cell phone charger and snip the plug off the end, strip the wires, and hook up the fan. I tried it out and it worked perfectly!

Now what I'm not sure of is how many fans would one 12v phone charger power? It says 12v and 1000mA

and here are the stats fo rmy fans:
Rated Voltage: 12VDC
Rated Current: 0.08+/-10%A
Power Input: 0.96W
1000mA = 1A

a 12v/1A charger will give you 12W output.

Power = Voltage * Current = 12V * 1A = 12W

If the fan is rated at 12V/0.08A or 0.96W, then you can run 12 fans off of it.

most cell phone chargers now are USB, so they're only 5V, 500mA-1A though. if that's what you have, 5V may or may not be enough to run 12V fans, but at a slower speed than at 12V.
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Old 10-12-11, 08:17 PM
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Re: How to convert 120v AC to 12v DC?

Originally Posted by namrfumot View Post
so if I went on Flea-Bay and bought a cheapy adapter thats 12v and 2000mA that's be 24 watts?
some cheapy eBay adapters might not provide rated power, but yes, 12V/2000mA is 24W. also, cheapy adapters may not provide clean power and may overheat. not saying it won't work, but i've had bad luck with some cheapos.
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Old 10-12-11, 08:29 PM
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Re: How to convert 120v AC to 12v DC?

Originally Posted by D.Pham00 View Post
some cheapy eBay adapters might not provide rated power, but yes, 12V/2000mA is 24W. also, cheapy adapters may not provide clean power and may overheat. not saying it won't work, but i've had bad luck with some cheapos.
Score I'll poke around at work...we must have some adapter from computer speakers and such...
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Old 10-12-11, 08:34 PM
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Re: How to convert 120v AC to 12v DC?

Ebay has some Casio adapters for under $12.....12v and 2500mA! score...thanks guys
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Old 10-12-11, 09:03 PM
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Re: How to convert 120v AC to 12v DC?

Another question...yes I'm an idiot. Does an adapter like this give 12v and 3000mA?

http://www.ebay.com/itm/12V-3A-DC-Po...item4aaf9ae306
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Old 10-12-11, 09:10 PM
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Re: How to convert 120v AC to 12v DC?

3A = 3000mA. The 12v is the same.
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Old 10-12-11, 09:11 PM
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Re: How to convert 120v AC to 12v DC?

Ok those are even cheaper then...does an adapter such as these only draw as much power as it needs? If so I'll jut get the biggest one I can find....
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Old 10-12-11, 09:55 PM
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Re: How to convert 120v AC to 12v DC?

Originally Posted by namrfumot View Post
Ok those are even cheaper then...does an adapter such as these only draw as much power as it needs? If so I'll jut get the biggest one I can find....
Yes, it should only use what it needs. Power efficiency would play a role in how much power consumption it uses, but a lot of times, it is difficult to find the power efficiently, and usually the efficiency depends on the power output.
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Old 10-12-11, 09:59 PM
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Re: How to convert 120v AC to 12v DC?

Ok...thanks for spoon-feeding me all this info guys. I'll go for the biggest, decent brand I can find....I've found some 5amp laptop adapters for under $10.
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Old 10-12-11, 10:57 PM
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Re: How to convert 120v AC to 12v DC?

Just remember to not reverse the polarity of the neutron flow.
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