I am not an electronics nerd. Yes, I can solder, but I can design only the simplest of electronic circuits. When I first saw the innards of one of Apple's 10W USB chargers, I was a little scared of the dense electronics inside. Ken Shirriff was not though. He opened one of Apple's 10W USB chargers, figured out how it works, and compared it to similar designs from Samsung and counterfeiters.
You can learn a lot from his analysis if you understand how switching power supplies, which convert the alternating current from your wall into semiconductor-friendly direct current. Does Ken think the $30 pricetag for an iPad charger is justified? According to Ken, not really:
[I was surprised to realize how enormous Apple's profit margins must be on these chargers. These chargers sell for about $30 (if not counterfeit), but that must be almost all profit. Samsung sells a very similar cube charger for about $6-$10, which I also disassembled. The Apple charger is higher quality and I estimate has about a dollar's worth of additional components inside. But it sells for $20 more.