[mythtv-users] NAS power supply

[John Drescher]

On Sun, Oct 5, 2008 at 10:25 AM, Yan Seiner <yan at seiner.com> wrote:
> I'm going to have to build an external HD enclosure.  What do people do
> for power supplies?  Power itself shouldn't be a problem; assuming a
> drive consumes 20W on spinup and 10W running then even 20 drives can be
> handled by a (relatively) modest 450 W PS.  No mobo in the enclosure, so
> no power for that.
>
> I've heard about people using resistors on a normal PS when it's used
> without a mobo.  I can only assume that the PS requires a load of some
> sort on the mobo connector to operate properly, but I'm not about to go
> slapping random resistors on the connector... :-)
>
I did this 4 years ago on a server that is still in operation to add
dual power supplies to accommodate 20 250GB WD SATA 1 drives to a
system. The problem was that the antec 450W power supply required a
0.5A load on the 3.3V rail.

So I put 2 10 ohm 10W wirewound resistors in parallel (and attached
them to a metal part of the case with hs compound) to achive this:

http://www.radioshack.com/search/index.jsp?kwCatId=&kw=10%20ohm&origkw=10%20ohm&sr=1

Note that 2 parallel 10 ohm resistors = 5 ohms

and by ohms law

I = V / R

so that for this circuit

I = 0.66A

which satisfied the 0.5A requirement.

With all of that said I am sure today  you can find power supplies
without a load requirement on the 3.3V rail so you will probably be
fine.

John