From: "John Jardine"
Subject: Re: Watt Meter Project....Attn Win
Date: Tue, 24 Dec 2002 18:08:10 -0000
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NNTP-Posting-Date: 24 Dec 2002 17:55:02 GMT
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John Woodgate wrote in message
> I read in sci.electronics.design that John Jardine
> wrote (in k>) about 'Watt Meter Project....Attn Win', on Tue, 24 Dec 2002:
> >I would have thought they 'meant' any waveform having asymmetry between
> >top and bottom half cycles. This implies a DC component, level shift due
> >even order harmonic distortions.
> It's also possible, even in the real world, to get asymmetrical half-
> cycles that have nevertheless equal or very nearly equal, areas, so no,
> or nearly no, d.c. component. This is one reason why the 'special
> waveform' criterion for Class D in IEC/EN 61000-3-2 had to be dropped.
> One half-cycle could be well into Class D, while the other was outside
> it! Actual measured waveforms were produced to the Working Group.
> Regards, John Woodgate, OOO - Own Opinions Only.
> Interested in professional sound reinforcement and distribution? Then go
> PLEASE do NOT copy news posts to me by E-MAIL!
It's interesting this, as I seem to remember years ago in WW mag a pic of an
audio test waveform that had this odd property. Didn't mean much at the time
but I occasionally wonder how they had made it work.
I've just quoted for a job where the manufacturer is having incidental
EN61000 flicker noise problems. I'll try and get myself a freebie copy ;-)