mikebiggs wrote:If your laptop has a dedicated USB "charging" port, that will provide a full 1 amp (1000mA), as the yellow charging port on my Thinkpad does. More than enough for the RPi ...or just use a double cable as suggested above.
bredman wrote:A lot of USB hosts will provide only 500mA, and this is not enough for the RPi. If you are lucky, your USB host will supply more than 500mA and you can use it OK.
That is a very badly worded instruction. It should read "This product shall only be connected to an external power supply rated at 5V DC, and a maximum current of at least 500mA."willhy wrote:I've just received my Raspberry Pi after months upon months of waiting, and I'm afraid to power it on.
The documentation I received in my package from element14 states "This product shall only be connected to an external power supply rated at 5v dc, and a maximum current of 500ma."
I *REALLY* wish someone would take the 5 minutes to fix that!willhy wrote:Thank you for clarifying. I suspected as much.
I asked Element 14 directly on twitter and they said that "It should read: "greater than 700mA recommended""
I'm not sure if the misprint is only in my manual or if others might see this as well, but either way it's been brought to their attention.
Almost, it would be OK to connect it to the 5v rail of a power supply as long as the polarity is correct, fuse optional but a good idea.Squirrelking wrote: By this logic would it be safe to say that it's perfectly acceptable to connect the Pi to any power supply with a 5V rail (ATX, XBOX, whatever) as long as a fuse is fitted and polarity is correct?
A massive power supply such as those you list can have other requirements, such as a minimum current. If you don't draw the minimum current then the 5V is not regulated. That would be a bad thing. It's perfectly possible to use supplies of this size with the RaspPi, but you should know what you are doing. I'm using one myself with a maximum current of 9A. (That one you really have to know what you're doing; there's 400V DC on that circuit board.)Squirrelking wrote:By this logic would it be safe to say that it's perfectly acceptable to connect the Pi to any power supply with a 5V rail (ATX, XBOX, whatever) as long as a fuse is fitted and polarity is correct?
You will find out if you search the internet for "ATX power supply as bench supply".Squirrelking wrote:I'll take a look at the minimum current issue, is that likely to be displayed on the rating plate of the device or will I have to go hunting for data sheets?
I have the impression that this is a myth, with everybody repeating what they've heard. Some powersupplies might require this, but I'd think most will not.bredman wrote: You will find out if you search the internet for "ATX power supply as bench supply".
In general, you will need to put a dummy load on the 5v and 12v rails, otherwise the ATX supply will refuse to turn on. You will probably need to burn at least 30 watts. Not very practical to power a Raspberry Pi that only needs a few watts.