Subject: Re: Smallest component to step down 240VAC to 18VDC?
Date: Sun, 13 Oct 2002 21:45:06 -0700
Organization: SCN Research of Tigard, Oregon, USA.
References: <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com>
NNTP-Posting-Date: Mon, 14 Oct 2002 04:46:47 +0000 (UTC)
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They make some regulators for stepping down up to 265VAC to
DC switching regulators, but I don't think they are isolated.
"Keith R. Williams" wrote in message
> In article <firstname.lastname@example.org>, a?n?g?e?
> email@example.com says...
> > On Wed, 9 Oct 2002 13:51:47 -0400, Keith R. Williams
> > wrote:
> > >Even if it were 230V that it would take 30 regulators ( (230-16)/7 ) if
> > >each was 7V. But since it's 320V, that's *43* regulators.
> > >Well, the power dissipation would be (230V-16V)*4.5A or over 1300W (and
> > >you think Athlons are hot ;-)! You could dry your hair while you
> > >design your web pages!
> > I'm not going to do it, since obviously it's not a good idea. (No
> > thanks, I do not plan on having my 3 minutes of fame by getting a
> > Darwin)
> More like three seconds of flame! ;-)
> > But I would like to understand why, since I'm still confused on this
> > thousand watt figure being raised by everybody. I think I sorta get it
> > now.
> > ie current through all parts should be the same, thus even after I
> > split the 230V over x regulators, the 230V will still see the 4.5A and
> > I still get thousand over watt dissipation?
> Again, it's 320V (your 230 is RMS, times 1.4 gets peak), and yes.
> 4.5A times 320V, is...
> Well, your laptop will take 16V times 4.5A of the juice. SO that
> means (320-16)*4.5=1300W. Hot.hot.hot.
> > Speaking of the no ground... I realize I don't really know which pin
> > of the AC plug does power come in. Does the AC oscillates between the
> > live and neutral, or does it do the +/-230V wrt to the ground pin?
> I believe you have a Brit system in .sg. They have a single
> phase 230V and neutral (rather than our split phase 120-N or 120-
> N-120). Your hot oscillates between +320V and -320V (with
> respect to neutral). Your neutral should be very close to ground.
> BTW, 320V is not my typical dyslexic tupo. I mean 320V (1.4*
> I don't know if your system is "polarized" (hot differentiated
> from neutral at the outlet) as ours is. Our neutral socket is
> larger than the hot. Devices that need to know hot (typically
> upper-right) from neutral (upper left) have a larger spade for
> the neutral or are keyed off the ground pin (low-center).
> ...though at work they insist on mounting the outlets upside-down
> (their theory is that any falling metal should hit the ground