N00b amp question

[Phillip Lamb]

I have a device (case fan) that I'm using to build a stir plate. It's got a power requirement of 12v/0.390A (O_o) and I'm having difficulty locating a reasonably-priced wallwort to power the thing. Can I use 12v/300mA and get away with it?

Thanks! sorry for the n00b question, I'd normally go to google with something this simple but it's not being very helpful today.

-pl

[doug brantner]

Not sure what you're trying to build, but in general, you want to
oversize for current.

If you need 390mA and your wall wort is only rated for 300mA, that's
not good. As long as the voltage is correct, you could use one with a
higher amperage rating (ie. 500mA). Also make sure the type of current
is correct (AC or DC)- some wall warts output AC.

That being said, I'm used to working with hundreds of amps, so I'm not
really sure how much difference 90mA makes. It probably depends on the
wire size & component ratings in the wall wart.
If desperate, you could try your wall wart & see if it doesn't
overheat, but be careful & keep in mind operating outside of the
ratings can be risky, especially over long periods of time (ie. fire
hazard).

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[Foxx D'Gamma]

If you use a wall wart that is underpowered with current, you can damage or burn out the wall wart. If you need 300mA and draw 390mA you will draw too much from the wall wart. The rating on the wall wart itself is the max draw. Even if you had an itty bitty LED only needing 10mA, and your PSU is 1000A, thats fine. Head Doug's warning, make sure your voltage is in the proper range you need. Also the proper current type, AC or DC.

A 12V 500mA wall wart should do fine.