[shuttertalk]

This is not photography related, but I thought it was interesting how something as innocuous as an iPhone charger can contain so much well designed circuitry in a tiny package.

Apple's power adapter is clearly a high-quality power supply designed to produce carefully filtered power. Apple has obviously gone to extra effort to reduce EMI interference, probably to keep the charger from interfering with the touchscreen. When I opened the charger up, I expected to find a standard design, but I've compared the charger to the Samsung charger and several other high-quality industry designs,[17] and Apple goes beyond these designs in several ways.

...

Apple's design provides extra safety in a few ways that were discussed earlier: the super-strong AC prongs, and the complex over-temperature / over-voltage shutdown circuit. Apple's isolation distance between primary and secondary appears to go beyond the regulations.

http://www.arcfn.com/2012/05/apple-iphon...ality.html

For a bit of a laugh (actually it's probably not a laughing matter) the author also looks at the insides of a cheap Chinese charger purchased for $2.79.

The UL has complex safety specifications on how much distance (known as "creepage" and "clearance") there must be between the primary and secondary sides to prevent a shock hazard.[6] The rules are complicated and I'm no expert, but I think at least 3 or 4 mm is required. On this power supply, the average distance is about 1 millimeter. The clearance distance below R8 on the right is somewhat less than one millimeter (notice that white line crosses the PCB trace to the left of R8).

I wondered how this power supply could have met the UL standards with clearance less than 1 mm. Looking at the charger case more closely, I noticed that it didn't list any safety certifications, or even a manufacturer. I suddenly realized that purchasing the cheapest possible charger on eBay from an unknown manufacturer in China could actually be a safety hazard. Note that this sub-millimeter gap is all that's protecting you and your phone from potentially-lethal 340 volts.

http://www.arcfn.com/2012/03/inside-chea...y-you.html

Scary - especially when you know quality control is not the best in China, and less than 1mm is separating you from life or death!