[mythtv-users] Desk Top Power

[Stephen Villano]

They use transformers, just that they're high frequency transformers,
rather than mains frequency transformers.
http://uk.rs-online.com/web/c/power-supplies-transformers/transformers/switch-mode-power-supply-smps-transformers/
Example:
http://uk.rs-online.com/web/p/switch-mode-power-supply-smps-transformers/5225989/

On 5/18/15, Michael Watson <michael at thewatsonfamily.id.au> wrote:
> 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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