[ale] OT: single rail 12V PSU, NUC, and you

[Damon L. Chesser]

On 11/06/2014 02:45 PM, Alex Carver wrote:
> On 2014-11-06 11:02, Damon L. Chesser wrote:
>> I am building my own "orange box" only using NUC with celerons, 4GB ram
>> and 65Gb ssd in each.
>>
>> I plan on having 10 of these devices mounted on a board with two 1Ge
>> destkop switchs (8 ports each).
>>
>> The purpose it to have an inexpensive, but many physical "servers" for
>> lab purposes to learn new tech or this cloud vs that cloud, etc.  Hence
>> sticking with x86 vs ARM (which would cost less).
>>
>> they draw perhaps 13W power under load, but have rather large wall warts
>> instead of in line converters. The dc converters are labled as 12v, 3a out.
>>
>> Simple math, 3a x 10 + 2 (for the Netgear prosafe switches rated at 12V
>> 1a each) is only 32A.
>>
>> I can find PSU with single rail 12Vdc out at 72a and higher.
>>
>> Questions:
>>
>> 1.  do I need to load down a PS other leads to power it up (perhaps
>> jumper to say "it is connected") and will it hurt the PS?
>>
>> 2.  where do I find a supply of the dc barrel connectors to build the
>> power cable from some sort of "power strip" to the NUCs female barrel
>> input?
>>
>> 3.  is there some other solution?
>>
>>
>> I could just run quite a few power strips since these wars all take more
>> than one "plug" space,  but that becomes bulky and awkward.
>>
>> Any ideas?
>>
>> This will all be mounted on a plywood base that can hang on a wall,
>> something like 2' x 4'.
> For now, since they're new, I would stick with the provided independent
> power supplies so you don't void the warranty.  You can buy short
> extension cords that are only six inches long made specifically to
> ensure that wall warts don't block up other ports on a power strip.  The
> extension cords would probably be much cheaper than any other option.
> The current draw at the wall (120V) side is only going to be about 8
> amps which is well within the range of any set of multiple power strips
> combined.
>
> Here is one example, there are many like this from a variety of places:
>
> http://www.amazon.com/Ziotek-ZT1212542-Liberator-14-Inch-Extension/dp/B000EWVSZK/ref=sr_1_2?ie=UTF8&qid=1415302898&sr=8-2&keywords=wall+wart+cable
>
>
>
> Running 72 amps of DC power means you need some very large distribution
> cabling.  I'm not sure what power supply you found but most likely it is
> using multiple output terminals to ensure it can supply the requested
> current.  Power supplies that big would typically have several terminals
> and you would need to use all of them equally to ensure you don't
> overheat a terminal.  However, without a link there's no way to know
> what you found and answer your specific question about the supply.
> Still, I would skip that idea entirely and just use the provided power
> supplies with the wall wart cables.

Good advise, I was also concerned with the idea of pumping 34a 12Vdc 
around.  Simple.  it will work.  Thanks.

>
> However, for sake of completeness you can buy the barrel connectors from
> an electronics supplier such as DigiKey, Mouser, Newark, etc.  They are
> usually specified as OD x ID in millimeters (e.g. 5.5 x 2.1 mm).
>
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-- 
Damon at damtek.com
404-271-8699