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From: email@example.com (Robin)
Subject: Re: Smallest component to step down 240VAC to 18VDC?
Date: 10 Oct 2002 03:18:01 -0700
References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>
NNTP-Posting-Date: 10 Oct 2002 10:18:01 GMT
If the load is your laptop then, even if the PSU is working correctly
or incorrectly, there will probably be a high voltage drop across the
PSU leaving a low drop across the load (your laptop).
But if you replace the load with your body i.e. increase the load by
hundreds of kohms, then, there is the possibility (via bad design or a
fault) that the voltage drop across the psu will be small and the
voltage drop across you will be large.
e.g. My washing machine tripped it's (residual earth) contact breaker.
I took the earth off it and finished the washing cycle but the chassis
was now quite painful to touch ("off load" it was 240 V; "on load"
i.e. via my body it was 70 V). The conducting path was via a water
If said machine had been conected to the mains via an isolating
transformer then when I touched the chassis, that particular "feed
side" of the transformer would have been "connected" to ground via my
body but because the secondary winding is not "directly connected" to
the "hot" side of the mains, it is free to "float" down to ground,
pulled there my body's load, reducing the voltage across me to ~zero.
email@example.com (The little lost angel) wrote in message news:<firstname.lastname@example.org>...
> On Wed, 9 Oct 2002 13:51:47 -0400, Keith R. Williams
> 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
> 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?
> 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?
> L.Angel: I'm looking for web design work.
> If you need basic to med complexity webpages at affordable rates, email me :)
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