And for our Next Trick ... How 'bout a diyTrionic?

[garfield at pilgrimhouse.com]

On Tue, 5 May 1998 00:06:12 -0400, cosmic.ray at juno.com (Raymond C
Drouillard) wrote:

>I remember this thread from a few weeks ago.  I seem to recall someone
>mentioning that around 80V DC is put between ground and the end of the
>coil opposite the spark output.  That way, the circuitry doesn't have to
>withstand the multi-kilovolt spike of the spark.

Uh, actually, I'm not quite sure I totally believe the block diagram in
the Saab book, but it shows the 80V source FLOATING on TOP of the HV
secondary, not between gnd and the spark gap. FWIW. With a little
research I should be able to get to the bottom of this seeming oddity,
but you're right about the issue of "withstanding" the HV if it does
indeed sit on the HV secondary. Ah, what is life without a few
mysteries.

>If that's the case, it
>can only be used with a distributerless system.  The gap in the
>distributer would leave you with an open circuit.

Yes, I think you're right, this technique is probably only suitable for
direct IGN systems. But that ain't so bad. Lots of nice small per-plug
coils available. We really WON'T know what the actual limitations are
until we get the articles together and some of us start looking into it
further. That's just part of the fun.

>Is this what you plan on doing, or are you going to come up with a
>circuit that will read a few milliamps of current and still withstand the
>big zap?

I'm figuring to tap into the research already done, and apply it, not
get into any new basic technology meself. I'm more a development
engineer than a researcher. At this point, the only system of this kind
that I know of that's been deployed in the field is the Saab stuff,
which IS direct per-plug IGN, so if that's all that's possible using
this technique, I consider the benefits EASILY worth the slight eXtra
effort to build the direct IGN system it needs to live with. That part's
pretty much a no-brainer. Besides, I'm an admirer of per-plug IGN,
anyways, so I won't need my arm twisted much by ION to make me go in
that direction.

An interesting little sidebar:

The Saab system starts up in a bootstrap fashion, firing pairs of plugs
and injectors at first, to get the engine started and the Ionization
circuitry up and running, since until that's up, all it has is a crank
sensor. Then once it's getting pulses from the Ionization detectors, it
switches to full sequential on both IGN and INJ. Neat, huh? It also does
some cool oddsNends kinda stuff at startup and shutdown, like
multi-sparking during cranking, and then when you shut the engine down,
after fuel delivery is shut off, it sparks the plugs a pile of times to
clean them off. Clever them Swedes. Actually a better word would be
"elegant". There is something very elegant and alluring about the whole
design; that's one of the reasons I thot ION should be refered to as a
"she", unlike that EGOR dude. He's got some interesting tricks, but he's
more of a meatNpotatoes kinda guy. Not this ION lady; she's very slinky.

Garfield the Anthropomorphite