sascha-ml-ui-sugar-olpc-devel at silbe.org
Thu May 13 10:18:51 EDT 2010
On Thu, May 13, 2010 at 09:24:17AM -0400, John Watlington wrote:
>> FWIW, I've also used a ATX power supply to power an XO-1, but stopped
>> doing so once I discovered why the XO-1.5 would run from it: Being a
>> cheap model, it regulated only the 5V rail, so the 12V rail dropped
>> down to 9V with a switched-on XO-1 connected to it. The XO-1 barely
>> coped (the power light started flickering some time ago, probably due
>> to the power supply aging and delivering an even lower voltage than
>> before) and the XO-1.5 (without MPPT ECO) didn't like it at all
>> (whining noise, LED off).
>> Summary: If you're trying to replicate this setup, make sure your PC
>> power supply regulates the 12V rail (just hook up some load and check
>> the voltage).
> Many higher power supplies like AT/ATX power supplies don't
> work properly when unloaded. I bet if you draw a couple of
> amps from the +5V supply, you would find that the +12V supply
> starts working fine.
In what way is that different from what I wrote? Or are you saying that
once I draw a certain amount of current from the 5V rail, the 12V one
will be properly regulated (i.e. keeping the voltage stable at 12V +/-
10% regardless of the current draw on the 12V rail)?
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