# correct AC transformer for DC motor



## zmbombr (Nov 19, 2012)

*too much wattage?*

I am wanting to use a reclaimed computer fan motor for a particular application. I have also found numerous old AC transformers with various wattage output. 

my question is how far outside the prescribed wattage can I go?

fan motor rated 12v .5 A

best transformer output 13v .8A

is that too much? will it kill the motor eventually?


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## rwaudio (May 22, 2008)

zmbombr said:


> I am wanting to use a reclaimed computer fan motor for a particular application. I have also found numerous old AC transformers with various wattage output.
> 
> my question is how far outside the prescribed wattage can I go?
> 
> ...


As long as the transformer output is DC you will be just fine, it will run slightly above rated RPM but also should be just fine.

Just because the power supply is rated at .8A doesn't mean that's what it's will put out into any load. It will put out up to .8A, some have a minimum load but you will be above that with a .5A draw.


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## Roy Von Rogers (Mar 21, 2009)

*Re: too much wattage?*



zmbombr said:


> I am wanting to use a reclaimed computer fan motor for a particular application. I have also found numerous old AC transformers with various wattage output.
> 
> my question is how far outside the prescribed wattage can I go?
> 
> ...


The wattage has nothing to do with it, the wattage is what is used, its amps times voltage. The motor doesnt care as long it has the proper voltage and has enough amps/watts to run the motor. The specs on the motor is 12v and uses/needs .5 amps.

And btw the fan is a dc fan motor, the output of a transformer is ac, it needs to be recified to run a dc motor. Also note when you rectify 13v your dc voltage will be higher, and may be too high for a 12v motor. 

Please do some reading on the subject.

Roy


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## Woodsmith (Jun 5, 2008)

zmbombr: Please do not post multiple threads asking the same question.

Also is this relevant to electric vehicles?

Admin.


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