[mythtv-users] Desk Top Power

[Simon Hobson]

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.



Simon Hobson