[mythtv-users] Desk Top Power

[Christopher Kerr]

On 15 May 2015 at 09:50, Daryl McDonald <darylangela at gmail.com> wrote:

>
> Being retired I do have time to throw switches, unfortunately not every
> time the machine goes up or down, and the computer's memory is far superior
> to mine. And John, did I mention that I'm Scot! Is there really no one out
> there that has tried this idea?
>

It can be done, and it's usually perfectly safe. You just need to make
adapters from the "Molex" (4 pin Mate-N-Lok) connectors to whatever barrel
plug your devices require, ensuring you get the polarity and voltage right.
Double check that none of the devices are expecting an AC supply - there
are still a few oddball devices that just put a transformer in the wallwart
and do rectification and regulation onboard. Also check how much power your
supply is rated for on the 5V rail - they tend to be a bit on the weedy
side.

If you need to handle other voltages (eg. 9V) you could regulate the 12V
supply down to the required voltage, but the details of doing this properly
are outside the scope of this email.

Old supplies would sometimes get unstable if the 5V rail was heavily loaded
and the 12V rail wasn't, but modern supplies (particularly the kind that
regulate the 5V rail off the 12V rail anyway) don't seem to have this issue.

 There are various other possible issues (startup surge power being the
first to mind) but you should be fine if you don't go overboard.

- Chris Kerr
(I am an Electrical Engineer. I am not an electrician, and cannot tell you
what quirks may exist in your local electricity and wiring codes)
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