Scope pics...

[Gerald Pelnar]

Hey Bruce--

I thought this was on DIY instead of GMECM.

Anyway, you have put forth a very good explanation. The only
problem I see, which may be a sticking point, is your use of A/C
rather than a more accurate discription of varying DC. AC
implies the current alternates (changes direction) which it doesn't,
except for some of the ocillations after the spark extinguishes, where
the voltage may drop below zero.

Gerald Pelnar
wd0fyf at mpks.net
http://www.mpks.net/homepage/wd0fyf/
McPherson, KS


----- Original Message -----
From: Bruce Plecan <nacelp at bright.net>
To: <gmecm at diy-efi.org>
Sent: Friday, November 10, 2000 10:38 PM
Subject: Fw: Scope pics...


>
>
> Thanks Shannen
> If ya all (who are still interested), look at this, maybe we can get
> somewhere.
>
>  http://www.aeswave.com/framedcatalog/product_0112sec.htm#accessories
>
> Starting at the left edge:
>
> Is a *12* volt signal,  then we have the points close signal (note there
are
> coil condenser oscillations {ie A/C}), As the coil saturates you see the
> voltage build, then the point open signal a huge vertical spike, note that
> the are some *notches* *steps* as the voltage is at or near the max
voltage,
> these are the coil oscillations of the *ringing of the collapsing* fields,
> *typically* this spike is around 25Kv, and is when the ionization is
forming
> between the electrodes, finally there is an arc over, and the *firing
line*
> reflects that with a horizontial segment (again typ. 12 Kv), that can vary
> (at idle) from .7 to 1.8 msec. that is the time where there is an
> established arc.  Once there is no longer enough *ions* between the
> electrodes, the voltage is no longer high enough to maintain an arc and
the
> arc stops, and there is the large drop to 0 and even slightly less.   But,
> there is the current that was shut off still ringing in the system
remember
> the points are still open so there is still energy to disipate,  we ran
out
> of ions for a 12Kv path so we have 11.5Kv (about) that will have to
> disipate, and then we have the large coil condneser oscillations.  Then we
> go off screen, and would again begin at the l/h border, and begin the
cycle
> all over again.
>    Other then at the + side of the coil everything else is voltages from
the
> collapsing fields weither charging or discharging,  the coil, A/C
>
> Take a transformer,
>    Put a meter across  the secondary posts,
>    Apply power to the primary,  secondary pegs for an instant, then goes
0,
> with the primary is still on, remove primary voltage another spike, again
> output goes to 0.   Transformers don't work on a strickly DC component,
> That's the best I can do.
> Slice it anyway you want but that is the only circumstance that explains
all
> the conditions for a Waste spark.   IE one plug, can fire reguardless of
the
> is going on with the other.
>
> Take a convention autotransformer with a point open signal the one side of
> the secondary is only to 12+ thru the primary.   Since one side of the
> secondary is open to ground I guess the plug never fires.
>
> You check for spark with a grounded tester so that there is some control
of
> spark energy.
> Opening both sides of a secondary side of ignition coil will force then
> spark energy to disipate somewhere, and that is what ever is the path of
> least resistance.   If the points are open the A/C will just ride along
the
> 12+ supply side just fine.   Well til the capacidance (?) of the battery
> *absorbs* it...
>
> HTH
> Bruce
>
>
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