# I need a new 12 volt AC adapter; do amps matter?

Asked by linuxgnuru (207) May 26th, 2010

One of my AC adapters got fried and I need a new one. I’m curious if the amperage matters? I’ve seen some ranging from 1.0, 1.5, and 2.0 amps but I’m afraid to get anything that might damage my device.

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Amperage does matter. if you do not use the proper amperage for a certain device, it will either “fry” again or not work at all. i had this problem with an extended volume control on a hearing phone for my deaf mother. i could not find the proper amperage AC adapter to run the device. i took the phone to Radio Shack and they solved the problem….pronto.

Take your device to Radio Shack. they have ways of determining which AC adapter is correct. they also have the best selection of AC adapters i have ever seen. they were very helpful at RS.

Yes, Amps (like size) matters. Too small and it won’t be big enough to power your device. Too high and it could pop the device’s internal fuse.

Look at the unit you have now. It will say something like “12 V AC” or “12V DC” and either it will say the Amps or the Watts. Let’s say for example “2 Amps”. Remember from high school science you learned that Watts = Volts x Amps. So your device is 12×2 = 24 Watts. So a “12 V, 2 Amp” unit is the same as a “12 V, 24 W” unit.
When you buy a new unit make sure it is the right size.

LuckyGuy (39094)

It depends on what the adapter is used for. A lot of AC adapters have an open circuit voltage that is more than the nominal rating. They’re expected to drop to 12V under the device’s load. If you use one that has a higher amperage rating than the original, you could end up with too much voltage. If the adapter is regulated at 12V, then you’re OK as long as it’s rated at least the same amperage as the original.

If you have a voltmeter handy, you can check this for yourself. However, it’s usually best to replace an adapter with one of the same type.

@worriedguy – I would ad: also be mindful of the polarity of the jack on the device. It should be imprinted right next to the voltage requirements near the jack.

When you buy one of those all purpose adapters with the various plugs to fit everything, it’ll let you reverse the polarity of the adapter.

If you’re unsure, just find the right sized plug for the jack and plug it in. If the device doesn’t come on right away, unplug it, reverse the pins on the adapter plug and re-insert it.

That should do it!

stratman37 (8678)

@stratman37 Yep . You have to check polarity. Thanks.

LuckyGuy (39094)

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