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From: Jeff Wisnia
Subject: Re: Wall wart with two blade polarized plug,,,Why?
Date: Wed, 02 Oct 2002 18:50:38 -0400
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Kevin McMurtrie wrote:
> In article <3D9A856D.99A017C7@110.net>, Jeff Wisnia
> >I'm trying to think of a realistic reason why my little TV's 120 vac -
> >12 vdc 1.0 amp simple xformer/bridge rectifier wall wart needs one of
> >its two input blades wider than the other so that it won't insert into
> >an duplex outlet in a convenient direction. (i.e. so its body doesn't
> >interfere with a right angle cord plug already in the other half of the
> >I've got half a drawer full of wall warts from various now-discarded
> >devices, and all but one have equal width plug blades and can be
> >pluggged into a receptical "either way".
> >Before I file down that wide blade, did I overlook anything? Maybe the
> >designer of this wall wart has the wide blade connected to the end of
> >the transformer primary nearest the secondary so that an insulation
> >breakdown there doesn't connect the hot side of the line to the low
> >voltage circuitry? That seems a stretch to me.
> >Anybody know for sure?
> >Thanks guys,
> There's likely a resistor between the DC negative and the AC neutral.
> TV's throw off some electricity from the high voltage they use. All TVs
> powered off AC either have a hot chassis or a partial connection to the
> AC neutral. A fully insulated chassis would eventually result in
> something arcing over.
Aha! Thanks, I sure hadn't thought of that. I'll verify it with an ohmmeter.
> Your .sig needs a space after the dashes.
Please elucidate on that one, I'm not understanding. Why is a space required
Jeff Wisnia Brass Rat '57 ee W1BSV
"Liberalism is the art of looking for trouble, finding it, misdiagnosing it
and then misapplying the wrong remedies." (Adapted from Sir Ernest Benn)
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