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<div class="moz-cite-prefix">On 5/17/15 1:07 AM, Karl Newman wrote:<br>
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cite="mid:CAOOwNt+r2yOmyMnyi8n=0axi_k+X+CoaZesds_f0z7MVq5DkWw@mail.gmail.com"
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<div class="gmail_quote">On Sat, May 16, 2015 at 10:54 AM,
Stephen P. Villano <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:stephen.p.villano@gmail.com"
target="_blank">stephen.p.villano@gmail.com</a>></span>
wrote:<br>
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On 5/16/15 12:59 PM, Simon Hobson wrote:<br>
<span class="">> Michael Watson <<a
moz-do-not-send="true"
href="mailto:michael@thewatsonfamily.id.au">michael@thewatsonfamily.id.au</a>>
wrote:<br>
> jrh <<a moz-do-not-send="true"
href="mailto:jharbestonus@gmail.com">jharbestonus@gmail.com</a>>
wrote:<br>
><br>
>> Regarding power imbalance or however it is
called, is this still an issue for power supplies built
today?<br>
> Yes I would say for a typical PC PSU.<br>
> The multiple outputs typically come from multiple
secondary windings and rectifiers from one transformer.
The feedback control operates on the primary output -
it's only possible to accurately regulate one output
without secondary regulators. The other rails will more
or less follow the main one - the relationship between
output voltages depends on the ratio of the number of
turns on the transformer, and the voltage drop in the
rectifier diodes and windings.<br>
> If you keep the load on the primary output
constant, then varying the load on one of the secondary
outputs will vary the voltage on that output - increase
load and the voltage will droop, reduce it and the
voltage will rise.<br>
><br>
</span>
Tesla and Edison had a longstanding argument, Tesla
advocated for<br>
alternating current, Edison advocated for direct current.
As alternating<br>
current has less losses in long transmission lines than
direct current,<br>
Tesla's argument won by means of feasibility.<br>
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<div>To be pedantic, at equivalent voltage &
particularly current levels, I think AC is actually more
lossy than DC due to skin effect, hysteresis and eddy
currents (although the last 2 probably mostly apply to
transformers). Tesla "won" because it's much
easier/efficient to change AC to high voltage suitable for
transmission and then back down again for distribution
using transformers.<br>
<br>
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<div>Karl<br>
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Which is *why* AC travels across significant portions of the US,
when DC was challenged to cross a city.<br>
The physics is easily apparent and ancient.<br>
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