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

[Alex Carver]

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.

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).