[mythtv-users] HD-PVR Power Adapters

[Mike Perkins]

On 04/10/15 07:24, Joseph Fry wrote:
> On Tue, Sep 29, 2015 at 6:33 PM, Richard Woelk <richardwoelk at gmail.com>
> wrote:
>
>> When my HDPVR 1212 power supplies started going, I cut the ends off and
>> connected them to a hard drive molex from inside the computer. This works
>> well, and the HDPVRs are actually a lot more stable.
>> It is probably a good idea to put a fuse in it.
>>
>
> I am just finishing rewiring my mythtv setup.
>
> I have 4 HDPVR's, and 2 usb ports (powering a Raspberry Pi and a little 8
> port switch) on the 5v rail and 4 Cisco STB's on the 12v rail all running
> off a standard ATX powersupply (think it's 400w).
>
> Based on the current ratings of all of the equipment's wallwarts, I am well
> under the rated current on both rails, and I doubt I would ever come close
> to the theoretical max since the equipment typically draws well under the
> maximum rating of it's wall wart.
>
> There is absolutely no doubt that my ATX power supply is more efficient
> than 10 wall warts would be, and the quality of the power is so much better.
>
> Took a little while to wire all of the barrel plugs and USB ports...
> everything is wired to Molex splitters, so I can change the power supply
> easily if it ever fails.
>
Be aware that things can work the other way around as well - your PSU may fail to produce the right 
voltages and/or regulate them well enough if the load is too low.

Most PSUs require some kind of minimum loading on one of the rails, usually the +5v rail, in order 
to provide a reference voltage the other rails can use.

Of course, every PSU is made different, YMMV etc.

-- 

Mike Perkins