My Raspberry Pi was shipped today by element14, but I started researching power supplies last week. A page on www.soronlin.org.uk titled Raspberry Pi Power Supplies indicates that any cell phone charger capable of providing 0.7A (or 700mA) of current should suffice, but the author recommends choosing a name-brand unit, and preferably one that provides 1A (1000mA). A post on www.raspberrypi.org titled “The Boreatton Scouts meet a Raspberry Pi” describes a setup using an “old BlackBerry 700mA charger”, which the Raspberry Pi was fine with until a few USB peripherals were added.
I tend to over-provision, so based on the recommendation to use a 2 amp adapter in this forum thread at www.raspberrypi.org titled “Adequate Power Supply Critical to Pi Stability”, I picked up an HP TouchPad Power Charger for $4.99 with free shipping from the HP Home & Home Office Store. (That’s an awesome price, by the way.)
It’s reportedly the same charger that originally shipped with the TouchPad, and it’s a 2.0 amp charger, so it should charge just about anything with a USB port, short of a notebook PC. It comes with a one-year warranty from HP, too. A good number of the reviews on Amazon.com complain that the included USB cable is lousy, but I have a number of short, 24AWG USB cables with ferrite cores from monoprice.com laying around, so no worries there.
Specs taken from the side of the PSU:
Input: 100-240V~50-60Hz 0.4A
Specs taken from the page at HP:
Maximum Output Power: 10 W
My only concern is that the 5.3 Volts exceeds the 5.0 Volts that the Raspberry Pi is designed for, but I’m reasonably assured this won’t be a problem. I have a multimeter, so I’ll be testing the voltage across the test points.
There is a good list of verified peripherals, including a number of known-good power adapters, at the RPi VerifiedPeripherals page at elinux.org. The HP Touchpad supply is listed among the known-good adapters, but it’s referred to as a “5V 2A Charger for HP Touchpad”.
Of course, monoprice has some USB chargers, too, and I’d probably pick up a 2.1A, 4 Port USB Wall Charger as a second choice (assuming it’s not still on backorder).