Coils for Ion

[garfield at pilgrimhouse.com]

On Thu, 4 Jun 1998 00:14:26 -0400, cosmic.ray at juno.com (Raymond C
Drouillard) wrote:

>I should get with my
>mechanic friend and test this out.  A capaciter to pick off the arc noise
>is a lot easier than a HV diode to read a current measured in microamps.

If this "a lot easier than" is refering to ION measurements, again, this
is NOT at all what is being measured in ION. The current across that
plug when it's arcing is NOT, no how, "measured in microamps", it's
orders of magnitude bigger. The current we're measuring with ION has
NOTHING to do with the spark current. I've said this over and over now.
OVER? We can't be having to go all the way back to ground zero on this.
ION measures ionization current in the plasma that remains AFTER the
flamefront, NOT the spark current. That's after BOTH the spark phase,
and the flame propagation phase, have PASSED.

I hope that comment above is intentionally comparing apples to oranges,
but somehow I fear it may not be. Say it ain't so.

>Taking the worst case (80 meg ohm and 50 Hy), I get a
>3db frequency of around 150 KHz.  That sounds kinda high... I think I'll
>double-check my math later when I'm less tired.
>
>Anyhow, I wasn't considering the ringing because I figured it would have
>to decay before we can get a good reading, anyhow.

Yeah, but the secondary ringing is exactly what characterizes the
IMPEDANCE of the secondary, which is how this whole canard worry of
yours began. Go back to your intial post, and read your expressed worry,
that the "reactive impedance of the coil" was gonna somehow effect ION's
signals it was needing to measure. That's why I said even a cursory
glance at the representative waveforms shows that the natural frequency
of the coil's secondary is WAY above the frequency components in the
ionization current; you can see that DIRECTLY on the graphs of the ion
signals, WHEREVER they're drawn, patents or papers. That's why I gave
you that URL AGAIN!

>Also, I believe that
>the ringing is due to the primary and the condenser (as in points, plugs,
>condenser) forming a parellel LC circuit.

This is not the domain of "belief", and the LC circuit that governs the
impedance of the *secondary* has NOTHING whatsoever to do with the
condenser in the primary, or if it's even there (many modern points-less
IGNs don't even HAVE a capacitor there, instead they've got a protection
flywheel/freewheel/flyback (whatever you wanna call it) diode there.

Whether there's a condenser there or no, or even if the primary were to
miraculously disappear once the field collapsed, the secondary still
rings on, as soon as the arc is extinguished, because it's due to the
SELF-RESONANCE of the secondary coil itself! This is a mistake someone
else made, in trying to defend your concerns/questions in private. The
LC circuit in the primary does NOT characterize the reactive impedance
of the secondary. How on earth CAN it? The primary rings, the secondary
rings; each would also ring were the other not even present, and they
even ring at different times; the primary as soon as the primary circuit
is opened, the secondary, as soon as the spark arc is extinguished.

One of the things I think that's annoyed me about this whole topic of
ION (thank God EGOR's technology was so far beyond us all but the
electrochemical guys, that we couldn't even PRETEND to know stuff about
how IT worked), and how she works, is that maybe this group has gotten
into the habit of talking about things in way too fuzzy a manner, with
glib quips on why this is why a certain thing works the way it does (I
mean, look at the series of snake-oil topics recently hosted), and you
just can't operate in this kinda wishy-washy mental fog, and discuss
something like ION. It ain't really all that deep, but deep enough you
just can't be confusing primary with secondary, the condenser in the
primary with the capacitance in the secondary winding, and asking about
frequency components in ION's signal while completely missing the
evidence to answer those questions in pictures of the waveform itself. I
mean, an electronics discussion isn't exactly the same as having a nice
vague chat about the weather or politics, over coffee.

There's just been too many cases of people talking about stuff they
didn't understand the basics of, and posturing as tho they understood
the more esoteric elements. Now, we wouldn't take too kindly to someone
coming on this group and confusing 2-cycle and 4-cycle combustion, or
equating that to 2-cyl vrs. 4-cyl, but that's been analogous to some of
the gaffs and folly in some of these threads. I dunno, maybe I'm
expecting too much, but hell's bells guys, if you don't know what ya
don't know, you're gonna sound like a bozo mosta the time! It takes some
baseline understanding of the E in EFI, to really talk about these
things. I guess I was assuming too much about where that baseline really
WAS. And maybe it's futile to try and raise it some, cuz if you wanna
argue about it needing to be raised (a fact at this point that I think
has been indisputable proven), as if I've been complaining too much
about the screwups, then we're gonna be perpetually in this mode of one
step forward, two steps back. I'm not saying AT ALL, that we all need to
have EE degrees, but those that wanna engage in the electrical parts of
the discussion oughta at LEAST have the basics of automotive electronics
down reasonably well. An EFI group is not the place to be teaching these
things; it's rather a given assumption that it's there already.

My mistake to assume so? Maybe. If so, I'm sure a duck outtta water,
ain't I?

Gar