This UL-listed 27 W, “wall wart"-style switching power adapter supplies up to 3 A at a regulated 9 VDC. The AC adapter works with input voltages of 100 – 240 VAC and has a 1.5 m (5 ft) DC power cord that is terminated by a center-positive, 5.5 × 2.1 mm barrel connector.
This UL-certified AC-to-DC converter gives you an easy way to power your DC electronics project from a US-style AC electrical socket. It uses a switching regulator to efficiently output up to 3 A at a near-constant regulated 9 VDC, even when no load is applied. The DC power cable is 5 ft (1.5 m) long and terminated with a center-positive, 5.5 × 2.1 mm barrel connector that works well with many Arduinos.