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From: David Brown on 21 Oct 2009 08:17
David Lesher wrote:
> David Brown <david(a)westcontrol.removethisbit.com> writes:
>
>
>> So you now agree that there is no such thing as a "TRUE sine wave"
>> output from an UPS? It's a pity that you then contradict yourself
>> /again/ later on.
>
>
> Well, I know of one design that I'd call same; but not sure you will.
> The best ferro-resonant UPS's are damn close. Of course, such are neither
> common or inexpensive.
>

I've no argument that you can generate very close to sine waves - for
most practical purposes, devices like these are effectively sinusoidal
with no harmonics that you normally need to consider. Every application
has its requirements for how good a sine wave it needs, and you can get
as close as you like (until you are limited by fundamental things like
thermal noise).

I've just been arguing about rodbot's descriptions of UPS outputs as
"true sine wave", and his claims that things like rotary converters and
the mains supply produce /pure/ sine waves with absolutely no harmonics.

> [But then the line itself is never purely sinusoidal, either; it come
> with flaws such as spikes and dropouts...]
>
> The real question is: does the load care if it's not? If all loads are
> switchers, usually not at all. Linear wall-warts may. Incandescent lamps
> won't have a clue.

Incandescent lamps /will/ care - they will prefer a square wave, because
there is less variation in the absolute current, and therefore less
variation in heating. This means less thermal and physical stress, and
a longer life for the same power output.

But I agree that the question is if the load cares or not. For many
purposes, a square wave should be better (though DC would be best), but
most devices are specified, optimised and tested with AC (at least
roughly sinusoidal) inputs.
From: David Brown on 21 Oct 2009 08:20
Rod Speed wrote:
<snip>

Ops, looks like you've blown a fuse again. That can't be good for your
heart at your age. Perhaps you should ask the nurse to up your valium
dosage (or is it lithium?).

From: Rod Speed on 21 Oct 2009 13:41
Some silly little pathological liar/pathetic excuse for a lying bullshit artist claiming to be
David Brown desperately attempted to bullshit and lie its way out of its predicament
and fooled absolutely no one at all, as always.


From: David Brown on 22 Oct 2009 06:30
<snip>
From: Rod Speed on 22 Oct 2009 15:02
David Brown wrote:
> <snip>

Pathetic.


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