I know I should know the answer to this question, but I don't.

Let's say I have a portable electrical device (such as a CD player) that can be plugged into a 4.5VDC 200mA wall mount adaptor. If I use a 4.5VDC 1A adaptor, will I blow it up, or cause other damage?

Related: why does an electrical device that uses 2 AA cells (3VDC) require a 4.5VDC wall mount adaptor? Is there a voltage limiter in the circuit? Could I then safely use a 5-6VDC adaptor?

Thanks
Al

More amps is ok if the voltage and polarity is right. Its like if you upgrade your PC power supply from 300 watts to 500 watts. If your PC only needs 280 Watts it will only draw what it needs.

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I agree with the above - using a 1A supply should be fine.

But you ask about voltage, and here is where it gets dicey.

you ask if you could use a 5-6vd adapter - I wouldn't try it. Yes, the device has voltage limting to 4.5v - they can design voltage limiting becuase they know that they'll get 4.5 from the adapter they sold you. If you put in 5 or 6, you'd be stressing the voltage limiting beyond what it was designed to do - you'd be taking your chances at frying something.

But maybe not- there isnt that big a difference between the 4.5v adapter and your 5-6v solution. people who have worked with devices like this can correct me here, because there are only so many cheap ways to regulate/limit voltage (especially in small consumer devices that only take 3v to run in the first place)- and those methods might accomadate 5-6v just fine.
And I said cheap - if it costs $.02 more per unit to allow a supply voltage of 5-6v, they probably didnt do it =)

So the short answer is: I don't know, but unless its a real expensive thing you wanna run - try it =)

-John

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Unless you know more about the specific "wall wart" and/or the device in question, it's not necessarily safe to assume that a much higher current rating (for the wall wart) fundamentally can't cause problems.

If the wall wart is truly a regulated DC power supply, that's great - it can deliver very close to the specified voltage at pretty much any load within its working range.

Many wall warts, however, are unregulated, and the voltage depends on the load. If you're loading it such that the current draw is substantially less than the rating, then the voltage will be higher than what's specified on the wall wart. If you have a meter, measure the no-load voltage on some wall warts some time - or look at Graph 1 in this article to see one example.

If you're using an unregulated wall wart far below its rated current, then you're back to what Angel was talking about - it depends how happy the device is to be fed voltage higher than it nominally requires.

First is the existing wall wart regulated or unregulated? If it is regulated then you might need to use a regulated supply. If not then you can use regulated or unregulated. Second you need to make sure you have the polarity correct. If backwards you could likely toast something.

As far as your second question, the device is probably using a voltage regulator so it needs some "headroom". This is called "dropout". Also it might have to do with what wall wart was available cheap. Could you use a higher voltage? Maybe! It just depends on what circuitry they have inside. It could cause a component or 2 to overheat.

Mike

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Thanks for all the help.

I guess it wasn't as simple a question as I initially thought, so I don't feel like too much of a dope.

At least about this....