I built my own charger back in 2005 when USB chargers were really expensive. Please excuse the ugly looks of that circuit - my soldering skills were not yet up to my usual high standards back then

The 7805 regulator delivers 1A at 5V, and completely "unintelligent" at that, so to say Since then, I have fried not a single device with it, using it on a regular basis. Will try it with my new KT