# AC Wall adaptor 9VDC 1A - Question

#### Broonox

Sep 3, 2010
5
230VAC Wall adaptor Output ~ 9VDC 1A, I was wondering if using this when my circuit only uses a fraction of 1A would do any damage to anything. I was thinking that only the required amount of power would come through the adaptor and that the 1A rating was a max. If not, can i use a resistor at the start of the circuit to lower the current from 1A to how ever many milliamps i need?. Thanks
Code:
9V--------------150Ohm-------------20mA-----------20mA----------------20mA-----------------0V
|                                                                           |
-------------------Motor---------------------Potentiometer-----------------------
|                                                100Ohm                         |
--------------Motor------------------------Potentiometer-------------------------

#### shrtrnd

Jan 15, 2010
3,869
Unless there's something particular about the circuit you're driving, it shouldn't hurt it.
Think about it like your power from the wall socket. I'm on 120VAC, I can run a 3W lightbulb or a 300W lightbulb from the same socket.
The 1A rating IS the max rating, not what you NEED to run your device at.
(I'm talking the current here, ...it's a whole 'nother story, if you're trying to run your circuit at other than the 9VDC the transformer (wall adapter) is designed to operate at.

#### Broonox

Sep 3, 2010
5
Thanks, just the answer i needed! and yea i understand the voltage aspects. Thanks heaps for the fast help, i just hadn't made a circuit that uses a wall adapter instead of batterys so i just needed to make sure. Rep + to you if i knew how

#### Resqueline

Jul 31, 2009
2,848
The unregulated adapters give the stated voltage at the stated (also max) current. At no load the voltage will rise to 30-40% more. Your circuit seems to be insensitive to that.

#### Broonox

Sep 3, 2010
5
wow. thanks thats very helpful to know.

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