> Therefore, by placing in the coil a condenser which is
> > connected across the interrupter points (P, Fig 3), we can absorb or
> > suppress the spark across the interupter points of the primary circuit
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> Think you were more correct than you think, Nolan.... <g>
Well ok. But in my own persecution, I must admit that I was thinking of
protecting
points from burning and sticking. Not part of a circuit tuning wizardry.
> causing current flow to fall to zero very rapidly. The only thing I
> wonder about the phrase "self-induced current" in the language about the
> primary is the date of the publication... does this section talk about
> magnetos??? (!) In a magneto, there would be magnetically-induced
> current in the primary. In a coil, it seems there would not be--after
> all, if self-induction occurred in both the primary and the secondary of
> the coil, it would be a perpetual motion machine, and would require no
> battery current. (?) <g>
Well, without going into the hupla of it all (because I can't remember it all),
I remember from my electronics classes that a coil of wire is also called an
inductor, and it self induces current by the collapsing magnetic field when the
supplied current is cut off. But this self inductance is a temporary phenomina,
decreasing all the time as the field collapses.
> The only other thing this may refer to is the tendency of one coil to
> induce current in the other. And that effect seems neglible, if one
> keeps in mind typical high-voltage behavior as seen on an oscilloscope.
> A normal trace shows an extremely sharp vertical rise in voltage in the
> spark lead, followed by a 1-2 kv drop in voltage as breakdown occurs
> across the air gap of the spark plug. The secondary discharges virtually
> all of its energy to ground through the arc, and there is a steep drop
> in voltage to near base line. At baseline, there are a series of
> diminishing oscillations in voltage with a peak of perhaps 2-300 volts
> in the secondary. Given the coil windings, that would translate to
> perhaps an induced oscillation of 0.2-0.3 volts in the primary, which
> seems almost negligible.
Remember your winding relationship. Lots of wraps of the primary to a
relatively
few of the secondary. The induction effect of small changes in the primary have
a substantial impact upon the the secondary.
> In short, the capacitor does two things--supresses the arc between the
> points as they open (which has two benefits--stops current leakage to
> ground through the arc, which quickly raises the voltage on the points
> side of primary, and keeps the points cleaner by preventing metal
> transfer from contact to contact through the arc), and creates a
> resonant circuit for all the previously mentioned reasons.
I don't know. That gets back to the old training we've all gotten, and as two
folk have just pointed out, that sure doesn't hold up in real world. I think
I'm more inclined to believe the Dykes manual, though I do not fully understand
it. But then, I'm so spoiled by electronic ignitions that I can't remember if
dwell is open time or closed time any longer! :-)
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