All I wanted to know about “wall wart” chargers

and information about bad counterfeit products to boot

A joy for me to read a really in-depth description of a switched-mode power supply, here for the iPad. As an electronics buff I could even enjoy detailed circuit diagrams! Safety differences between genuine and counterfeit products are quite obvious.

http://www.righto.com/2014/05/a-look-inside-ipad-chargers-pricey.html