EDIT: This reply was to your first posting.

@Nexus7: No, that's not correct. There is a transformer there, it's just that it's smaller. That's the major point of using a switch-mode charger: You can use a much smaller transformer.

A switch-mode charger works by first converting AC to DC, then chopping up the DC to a high frequency AC again (that's the 'switch' part), then transforming this high frequency AC to a low voltage AC, then finally converting to DC (5 volts, in this case).

The size of the transformer is proportional to the frequency: A 50Hz (or 60Hz, in the US) transformer needs a lot of iron. Increase the frequency and you can reduce the size and the amount of iron. Very small switch-mode power supplies/chargers are simply switching to a very high frequency, thus the transfomer can be made extra small.

I'm a little confused about this all, so sorry in advanced if I'm needing a second explanation. But I read a few posts back that the n900 charger cannot handle 100v or 240v? I'm going to Australia next week and I read that it uses the 240v, does that mean I shouldn't use my US charger there with an adapter?

It can handle it, all you need is a plug adapter.

All new switch-mode chargers from Nokia are multi-voltage (100V-240V) as far as I know. The N900 one certainly is, as is the N800 one, and any other I've seen. Switch-mode chargers in general are usually 100V-240V, not only Nokia ones. I have lots (Palm, Sharp, TomTom, Sony Ericsson, and more) and they are all 100V-240V.

For technical reasons it's much easier to design a switch-mode supply as multi-voltage, compared to older non-switch-mode chargers. The old, cube-shaped, heavy, non-switch-mode Nokia chargers weren't multi-voltage, at least not the old low-voltage ones (3.7V output instead of 5V).

Hopefully this thread has been answered. Considering the question could have been answered by reading the instructions that ship with the phone or even the label on the charger itself, I think it is safe to assume the device will work on either voltage setting. I have the US version in germany. The charger has been working since day one.

Most electronics nowadays with a global appeal are manufactured with an auto switching power supply as a way to cut fabrication cost amongst regions.

If your charger pops, blows up, etc. then you've misread the label on it, and it was never intended to be used at that voltage. The transformer issue mute point in this thread. No transformer is necessary.

If you ever wonder with any of your electronics just look for the 110(120)-240V sign (sometiems the - is a wavy line instead, means teh same thing) and you'll know it's auto switching. You just need a plug adapter and your set.

2d