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Re: Primary Q - A Brain Teaser
Aha! You have to scope the primary alone to see the effect. Sshot is
just fine and can be easily captured on a storage scope. With no high
frequency filtering, the zero crossing spikes blur the picture
considerably but with some LP filtering, the (macro) envelope can be
observed in all its glory. There is no doubt this happens and it
happens all the time in the primary. Secondary discharges can range
from exponential with some air streamers to linear with others and a
massive and sudden drop in amplitude with attachment. Ironically, the
Corums mentioned it in their literature (first observed/postulated
around the turn of the century) but then went on to model the gap as
an ordinary resistance :(
Malcolm
> Original Poster: Ed Phillips <evp-at-pacbell-dot-net>
>
> "Come again? The voltage is plotted on a linear scale. The
> proportional voltage drop of total voltage on the first cycle is
> different to that on the next. In absolute terms, the voltage drop is
> definitely the same isn't it? That's what the scope showed anyway.
>
> Malcolm"
>
> I haven't observed such behavior here, and the waveform of resonant
> decay has always looked exponential. However, in Zennek's classic book
> on wireless telegraphy he talks about a "linear decay", which would be
> very close to what you have said. If the arc resistance increases as
> the current drops, this could happen, I guess, but haven't noticed it
> here. Of course, pretty reluctant to bring a scope near a working coil,
> so have just observed the secondary voltage as picked up with a probe
> several feet away.
>
> Ed