Scope pics...

[Bruce Plecan]

> > Subject: Re: Scope pics...
> > The output side of transfomer is A/C.
> > It's just that simple.
> > You can argrue and dance around things all you want.
> > Biased high or low, it's A/C  might be riding on an dc bias,
> > A DC spark is lightning.

> Damn, do I feel like I'm really wading into some sharky waters by replying
> to this thread.
> My definition of DC is a non-time-varying waveform, and a spark certainly
> doesn't meet that definition.  So, I think we can say that this isn't a
> strict DC event, certainly not anything like hooking a scope to an ideal
DC
> power supply.

Score one for the home team.

> You seem to be saying that the bias is variable, though, and I'm not sure
I
> agree with that.  I'm certainly no e-mag expert (I sleepwalked through
both
> courses in college, did great grade-wise, but I don't remember a damn
> thing), but I do believe that the collapsing field on the primary side
> creates a event on the secondary side that is indeed predictable, at least
> with respect to current flow direction.

No really you can charge a cap with, and just as easily light a neon bulb.

> Now, if you look at the waveform, there's certainly a lot of A/C riding
> around on there.  After all, that's what creates all the spark noise that
> wire-wound plug wires, condenser caps, etc. try to extinguish.

I'll agree here

> But, having said that, I think you can establish a "negative" and
"positive"
> electrode on the plug.

Now your to a specfic case.
IF you use an autotransformer a example then the one leg of the secondary is
tied to gound at one point, in the coil saturation, cycle

  I don't want to act like I'm sticking my head in the
> sand, but I'm not going to believe that the spark current direction is a
> 50/50 proposition unless someone shows me.  If you look at the primary and
> secondary of any transformer, the secondary has a phase or polarity that's
> directly correlated with the primary.  Since we can always predict the
> polarity of the event occuring on the coil primary, we can also predict
the
> polarity of the event occuring in the secondary.

> > If the plug was firing a DC voltage just one side would erode.

> That would be true if electron flow was the only mechanism in plug
electrode
> erosion.  Since the electrodes see a very severe environment even without
> considering the spark event, I'm inclined to believe that the spark is not
> 100% responsible for plug wear.

Didn't say it was, there are lots of corrosive things going on (or things to
*wear out*) a plug.  But pale in comparison, to the erosion issue as far a
changing the air gap (IMO), which is what I'm talking about here.  The
center electrodes isolation brings in a whole nother basket of apples....
Bruce
>
>
> Eric Bryant
> mailto:bryante at ghsp.com
> http://www.novagate.com/~bryante

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