Is a USB Charger Universal?

Seems to me that a 5V smps wallwart and a USB cable will do..

~$6.00 from Digikey. Useful only off 120VAC like in the US or Canada.

See Ebay 5V adapters for travel or directly look for products for charging USB ported mp3 players.

Try to avoid buying a bulky surplus computer power supply for $10.00. :)

D from BC

Since all computer USB ports supply 5 volts, I think any 5 volt supply with a USB socket will work.

The top two on this catalog page are examples:

Better make sure it is low amps. Or you will fry it. USB outout is very low amps.

like this?

Martin

You probably won't have any trouble with your mp3 player. I have an iAudio unit that charges just fine from any USB port and matching cable I've tried it with.

HOWEVER...the same is NOT true of my Verizon/Motorola cell phone! @#$ %& thing will charge only from a USB cable/supply designed for the phone, or if I have the Motorola mobile phone software installed on the computer; otherwise I get an error message on the phone. Nutz.

Cheers, Tom

depending what ese you are doing, you might want to buy a USB battery supply ($10 or so) and an AA battery recharger....

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Cats, coffee, chocolate...vices to live by

As others have stated, a 5V supply (500 mA minimum) with a USB cable will probably suffice.

However, the USB standard describes a handshaking protocol that a well behaved USB client must engage in to draw more than 100 mA. If your player is well behaved, it may not kick into charging mode until it gets the go-ahead from a smart host. Wall warts, not being very smart, will never send this signal, so the client may remain in low power mode.

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Paul Hovnanian     mailto:Paul@Hovnanian.com
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Speed is n0 subsittute fo accurancy.

Interestingly, although I think my iAudio MP3 player will charge fine from a dumb wall-wart with USB cable, when I connect it to my Motorola phone charger (same mini-USB connector), it says, "Connected" -- apparently because the phone charger is "smart" to tell the phone it's OK to charge through it. The phone WON'T charge from a dumb wall wart--nor will it charge from a computer without the right software. Anyway, I believe in the "connected" state, the MP3 player won't charge; it's expecting to look like an external hard drive to a computer at that point. This is kind of the other side of the coin Paul was describing. Not everything that looks like it should work together -- does.

Cheers, Tom

If you mean, make sure the power supply has a low amperage rating, that makes no sense. The amperage rating of the power supply only needs to be high enough; as long as it's above the amount you need, you're fine - unless the voltage goes too high. If you need 5V, and you're trying to get, say

100mA (I have no idea if that's realistic but it's just an example), you'll get 100mA unless the power supply is not able to push that current. You won't get more. So even if the supply is rated for 5A, you're fine unless it tries to put out a higher voltage. You'll still only draw those 100mA. See what I mean: Ohm's Law: V=IR where R is the resistance of the load (the MP3 player), which won't change beyond a certain specified point. So consider R a constant. So, I, the current drawn, is directly proportional to V. If you want to get a higher current I, you'll have to bring up V. A power supply won't push up the voltage in order to give more current. (Sorry if I'm verbose, it's my first post; I just got excited. I'll die laughing if I just misunderstood your post!)