[mythtv-users] HD-PVR Power Adapters

[Joseph Fry]

On Sun, Oct 4, 2015 at 5:50 AM, Mike Perkins <mikep at randomtraveller.org.uk>
wrote:

> 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.


Definitely not a problem for me... but even if I had a PSU like that I
think I have plenty of load:

5V
4 x HDPVR = 8 Amps = 40W
1 x RPI = 1 Amp = 5W
1x switch = 1 Amp = 5W

12V
4 x STB = 8 Amps = 96W

Peak load would be about 150W.  I suspect that typical load will be far
less, but definitely above any minimum.
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