The voltage needs to be identical (or very close if you're feeling brave*) but the max current output on the adapter only needs to meet or exceed the requirement for the device.

I.e. if you have a 12v device needing 500mA a 12v 1A adapter will be fine. A 14v 500ma will not.

*I wouldn't be brave at all with modern electronics, but you used to be able to get away with it on some simpler devices.

I'd almost forgotten polarity. Apart from laptops which are their own special beast, I'm not sure I own anything with a good old fashioned transformer. Everything is either USB standardised or IEC to the appliance.

I'd guess (and it is a guess) that voltage is less of an issue now. Or maybe the same level of issue. (within reason)

With microcontrollers in everything these days the design is going to incorporate voltage regulators to provide either the 5v or 3.3v required for the logic side of things, so they shouldn't be affected. The rest of the circuit is probably no more or less voltage sensitive than older stuff.

If you supply 14v instead of 12v I'd guess that everything would run fine (albeit a bit hotter).

I'm not about to test it on anything I value, though :D

Yeah, maybe he should wrap the damn cord around his waist and stick the busines end in his mouth...

...said the bishop.

He could do well also to put about 7 strands of Christmas lights on as well.  :-D

Current condition... love it!  (dance)

I'd not want to put anything but a dman close match myself;  500mA more current could damage some things, not knowing how well that wall wart is made.
 
If you said that, you said a lot there.
  You'd think it would be standard, but it isn't.

 

The Chinese crap we get now?  8-O
 

You also might pop some cheap capacitors and electrolytics.

Quote: 

Exceedingly prudent, my good man.

But a current rating is simply a maximum output - current is drawn, not pushed, else your 60w lightbulb wouldn't last many minutes on a 1200w (average) circuit!

What Dan said - your power supplies are constant voltage, not constant current. The current drawn will be whatever is needed by the device.

Generally if you try and draw too much for an extended period the supply will die.

>>You also might pop some cheap capacitors and electrolytics.

Possibly, but 2 volts extra shouldnt dshouldn't do much. I'd wager that most components (even I'm cheap dodgy stuff) will be over specified because it's cheaper to go for the mass made stuff that's readily available than it is to get something that exactly matches your requirements.

If 14v would kill it, I'd wager it's got a fairly limited life on 12v anyway.

I should probably stress again that I'm just guessing here. I'm no electromagician.

If I have an electronic unit that I like, why would I take a chance that the adapter is crap and smokes it? You can with yours, I'll just use the right one thanks.

Tell that to the speaker amp I just repaired. Quote: 

Or maybe it is old and just can't handle it any more. Surely you've replaced a motherboard at least once for failed caps?
 

>>Surely you've replaced a motherboard at least once for failed caps

Nope, I missed that bandwagon. That debacle was due to badly made electrolytic capacitors, I think.

Yes, that is true. Bad or poorly made power supplies could accelarate the popcorn effect.

Had an ide channel on an old-ish mb (or associated caps, which were visibly popped) & an attached hdd blown by a lightning-induced power surge.

Yes, they don't like that much, do they?

Because the chance is zero, due to physics!

What surprised me was that it still ran off the other channel. Apparently the PSU itself was undamaged.

I'll bet you whistle in the dark as well, for safety.

I'm not with you now

That's OK. Basically I am saying that a poorly designed power supply can cause problems irrespective of it's design. You don't happen to agree with me. The fact that an adapter [may be] designed poorly, or the device,  may cause a problem when using an adapter that is over spec for the device it is to power and could damage it - even though your physics explanation makes sense. An inferior product can always damage another component.

Many people do not know that one is not really supposed to charge a cell phone via the same adaptor they charge their iPad with and vice versa, even though it is more or less "approved" by Apple, to wit:
  ~ From Popular Mechanics

I certainly wouldn't charge my iPad with the cell phone charger. I have seen it done and the adapter gets hot. The battery life of an iPhone likely will be shortened if one charges the cell (iPhone) via the iPad charger. The battery in the iPhone is not user replaceable (for most consumers), so despite Apple's assertion that they are compatible, a shortened battery life means Apple gets to sell a new phone if the battery life is poor and we all know iPhones do not enjoy stellar battery life anyway; so if the battery life is shortened by incorrect charger use, the chargers are not 100% compatible.

I don't have an iPhone so Fruitco devotees are free to abuse their equipment as they see fit. I'd say the same logic would apply to pretty much any consumer grade device that needs to be charged or would otherwise use an AC adapter, but that is my opinion only.

The red bit is factually wrong. A device will draw what it needs - all USB plugs are 5v, the only danger is plugging a high current device into a low current output.

How can an iPhone be 'exposed' to 2A when it only draws 1A.