9V 1A Adapter

A regulated 9 volt mains adapter with a standard barrel jack, sized for an Arduino's onboard regulator. Nine volts is a sensible choice for an Uno: high enough to be comfortably above the 7 volt minimum, but low enough that the linear regulator does not turn the excess into a lot of heat, which is exactly what happens with a 12 volt adapter. 9V is the ideal input for an Arduino's regulator; Runs cooler than a 12V adapter on the same board; Standard 2.1 mm centre-positive barrel jack; Regulated output for stable operation