Page 1 of 1

Re: Hows this for a power supply?

Posted: Mon Oct 31, 2011 1:25 pm
by stuporhero
http://www.maplin.co.uk/twin-output-usb ... ply-227633

[img]http://images.maplin.co.uk/300/N15GN.jpg[/img]

You could power the RasPi with one USB cable, and your USB hub with the other... Only downer is it might be a little tight @ 1A total output and a model B. Thoughts?

Re: Hows this for a power supply?

Posted: Mon Oct 31, 2011 1:26 pm
by stuporhero
And going to add this one too for better value:
http://www.maplin.co.uk/twin-usb-socket ... ply-115319

Re: Hows this for a power supply?

Posted: Mon Oct 31, 2011 2:48 pm
by abishur
I\'d probably choose something higher than 1A since they\'re estimating .7A running at full tilt for the model B. Now this is assuming .2A in use by the usb ports, so if you remove that from the full tilt estimate, that\'s still .5A to run the r-pi by itself. That PSU is certainly a good choice for just running the pi, but if you want to add some powered devices (Well mainly a power hungry hard drive) or a hub, IMHO I\'d start of with 1.5A minimum. Well I say that, but really it\'s a matter of supplying whatever amperage the hub requires (should be labeled on the hub itself) + another .5A for the pi.

Re: Hows this for a power supply?

Posted: Mon Oct 31, 2011 3:38 pm
by langlo94
Will the R-Pi supply more power to the USB ports if it is given more power?
For instance if I supply 1.2A the R-Pi draws .5A and the USB ports .2A that leaves .5A to be used.

Re: Hows this for a power supply?

Posted: Mon Oct 31, 2011 6:08 pm
by abishur
My understanding on this from what we\'ve discussed in the power supply thread is that there is a self-resetting fuse that will trip when too much current is drawn. What I infer from this statement is that there\'s some setting *somewhere* either on the ARM or the software or GPU or LAN9512 chip itself that allows them to limit the current being requested by the USB ports to the basic 100 mA. I do know for a fact that they\'ve stated that 100 mA is the max current to be drawn by the USB ports. I\'m just not sure where that limiting factor takes place.

**EDIT: I actually just read a post from Jamesh in another thread that says this understanding might be incorrect. I\'ve asked for clarification and will update once this get\'s answered! /EDIT**

Re: Hows this for a power supply?

Posted: Tue Nov 01, 2011 2:08 am
by abishur
Okay so it turns out we had misunderstood something. It\'s been made clear from an official source that the only limiting factor on how much the USB ports will be able to draw is the self resetting fuse. Right now, there\'s no official word on what that fuse will limit us to, but in theory the usb ports will be able to supply up to the fuse limit minus the power required to drive the r-pi itself.

Re: Hows this for a power supply?

Posted: Tue Nov 01, 2011 2:30 am
by kattle87
I do hope we get at least 600 mA for the devices, that means one should be able (given a good PSU) to get one power hungry and one \"energy-cheap\" device.
Besides, my nokia PSU is 1.2 A so if model B raspi eats 600m + 600m for USB, I\'ll be happy :P
And this could save buying a hub for a few people I guess.

Re: Hows this for a power supply?

Posted: Tue Nov 01, 2011 7:06 am
by langlo94
I\'ve got a nokia charger as well, they cost more than the R-Pi but damn they\'re good.

Re: Hows this for a power supply?

Posted: Tue Nov 01, 2011 6:18 pm
by duncan_pereira
I truly am sorry to have to intrude on this post but can anybody tell me whether these adapters (Or any others you can show me) can
a) Power the R-Pi, Ethernet, and two USB Wireless Receivers for a keyboard/mouse
b) Power a 2.5\'\' HDD connected to the Pi via a USB Y Cable

http://www.ebay.co.uk/itm/HQ-UK-Mains-P ... 1498wt_910

http://www.amazon.co.uk/Adapter-Charger ... 390&sr=8-1

Someone in another thread did kindly respond but I didn\'t have the heart to break to him that I don\'t live in mainland Europe and therefore require a 3-Pin Plug. Thanks in advance

Re: Hows this for a power supply?

Posted: Tue Nov 01, 2011 8:05 pm
by abishur
a 1A PSU will be sufficient to power the r-pi itself, but *probably* won\'t be enough to power the hard drive. That said you can just as easily buy two of them and hook the power portion of the y cable to the second PSU.

Re: Hows this for a power supply?

Posted: Tue Nov 01, 2011 9:05 pm
by duncan_pereira
My plan exactly :)

What\'s the diagnosis then? Am I good to go in ordering either of them?
And if so, which one?

Re: Hows this for a power supply?

Posted: Wed Nov 02, 2011 3:20 am
by Bacan
Maybe these folks will create a R-Pi device; that costs as much as a Model B!

http://www.engadget.com/2011/11/01/plug ... to-your-m/

Now we just need an Apple compatible power connector.

Re: Hows this for a power supply?

Posted: Wed Nov 02, 2011 3:21 pm
by stuporhero
I have the first one lying around (as a charger for my home and work mobile phones) - When these come out I\'ll attempt to connect a USB DVD drive (the el-cheapo LG one) and the Pi to it simultaneously.

Re: Hows this for a power supply?

Posted: Wed Nov 02, 2011 3:30 pm
by stuporhero
ahhhhh...

Bit expensive - but this should handle it:
http://www.maplin.co.uk/high-power-usb- ... ors-513509

Output Voltage: DC 5V
Output Current: 2.1A (2100mA)