[mythtv-users] Desk Top Power

[Michael Watson]

On 18/05/2015 1:30 AM, Simon Hobson wrote:
> Daryl McDonald <darylangela at gmail.com> wrote:
>
>> Would a small solar array, with battery charging and storage fit the single room senario?
> Yes, you could just pipe the DC at battery voltage (could be 12V, 24V, 48V depending on size - bigger systems tend to use higher voltages) around and then use DC-DC converters and point of use. This is effectively what telephone exchanges do - 48V battery banks on float charge, and massive busbars to the switchrooms.
> I believe some datacentres also do it.
>
>
> Michael Watson <michael at thewatsonfamily.id.au> wrote:
>
>> Please point me in the direction of an off the shelf product that has the scheduling capabilities, the scaling capabilities (slave backends, many hard drives, many different types of tuners - Analogue, DVB-T, DVB-S), and the ability to play my media on any device that I desire.  I may well buy one - (well I will need three to replace my MBE and two SBE/FE's)
> I did say largely. Because for a lot of people, they can just about do with whatever their cable/satellite provider stiffs them with. I know a **LOT** of people are (for example) perfectly happy with their Sky+ boxes and don't see what the fuss is about.
>
> The point is that people come to Myth because they want something different/better (by whatever criteria they define better). And for some, the "doing" is part of the fun.
>
>> Not seen a PC PSU that uses a transformer in several decades.  I think the Commodore64 and possibly the XT used a transformer based PSU
> Then you've not seen a PC PSU in several decades. All PSUs of the types being discussed here us a transformer, but it's run at high frequency so as to reduce the size. Find a schematic of a typical PSU, and you'll see a rectifier & storage cap front end, a controller circuit and switching element (could be one chip these days), and the switching element "chops" the DC (typically around 370V for UK mains) through the transformer primary.
> On the secondary side, there will be multiple windings, with rectifiers and smoothing caps. Typically ONE of the secondary voltages is sampled and fed back via an opto-isolator to control the switching at the input. The duty-cycle and/or frequency at the primary is altered to maintain the output voltage. Only the one output is fully regulated - the rest more or less follow but will vary depending on relative loadings.
>
> To have all outputs fully regulated means having multiple regulator circuits - and that isn't something you'll find in a budget PC PSU.
Yes you are correct.  But they are not transformer based PSUs.  So what 
I should have said to be correct is "Not seen a PC PSU that is 
transformer based in several decades"


>
>
> Simon Hobson
>
>
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