Mailinglist Archive: opensuse (1777 mails)

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Re: [opensuse] Moving to IPv6
  • From: Anton Aylward <anton.aylward@xxxxxxxxxx>
  • Date: Tue, 14 Sep 2010 16:16:07 -0400
  • Message-id: <4C8FD807.1040800@xxxxxxxxxx>
James Knott said the following on 09/14/2010 04:04 PM:
Anton Aylward wrote:
I don't know about heavy, though. Back in the mid 70s I needed a 50W
PSU for a piece of avionics I was working on.
Equipment for use on aircraft was severely weight constrained, compared
to elsewhere. Switching supplies weren't common until the '80s or so.
Prior to that, a power supply would need a heavy iron transformers, heat
sinks for analog regulators, large filter capacitors etc. IIRC,
aircraft equipment commonly used 400 Hz AC, which meant power supplies
could be built with smaller transformers, capacitors etc.

Indeed. But when I cranked the maths, I found that a 5V DC output that
was powering the semiconductor circuitry could be best achieved with a
30kHz switcher, and as a result very small - OTS - components. This was
dramatic enough at the time to get "why didn't I think of that"
reactions. Even back then, the 'norm" was rectification and voltage
droppers (aka resistor chains that grew hot).

I still wonder why we don't see more high-frequency switchers.

Someone is going to say "interference". Well, yes, but we know how to
deal with that, and there's a lot of high frequency noise anyway on the
power mains.....

--
There are two ways to slide easily through life: to believe everything
or to doubt everything; both ways save us from thinking.
-- Alfred Korzybski
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