how does the mobile charger work?

[neoandrewson]

how does the mobile charger work? they are too light. though they are rectifiers, they do not use transformers. (they are so light!) . i've heard that transformerless design consume lot of power and also they are dangerous. do they use any comparators or any other stuff like that?

 

[Nigel Goodwin]

They are usually switchmode, and do use a transformer - just a high frequency one - this makes them small and light.