ION Project Papers & Info Sources

[garfield at pilgrimhouse.com]

On Fri, 08 May 1998 21:57:05 -0700, garfield at pilgrimhouse.com wrote:

>On Fri, 08 May 98 19:37:02 -0700, Andrew Ghali <andrewg at netcom.com>
>wrote:
>>http://www.mecel.se/my_html/body_Ion_Sense.htm
>>
>>It mentions that Mecel has a patent issued in 1984 on ionization current
>>measurement used in Saab's DI system.
>
>Excellent little blurb there.

Just a couple follow-up comments and some NEWS. In looking at Mecel's
page a lil more, I see that the DI system (which DOES include ion
sensing for cylinder commutation) was intro'd in '87, which means this
stuff IS 10 years old. The other thing to note is that although the
patent was issued in '84 and deployed in '87, there is a real dearth of
articles/papers until the mid-ninties. In larger corporate circles, this
usually means there was a "ban" on publishing sensitive info until
several years and cash cows could be harvested. This is a likely
indication that Saab WAS INDEED tryna keep the stuff secret for quite a
few years.

Now the bit of news. You will note on the Mecel page that there's been a
DI system in the 9000s since 87/88? Well, a buddy of mine, who manages a
Saab parts dept. and whom I've been plying with questions since this all
started, today came up with some notes and a warrantee unit from a '90
Saab, and the lil board that does the Ion Detection stuff in those
earlier models is readily viewable (unlike the later models, that are
SERIOUSLY potted) if you remove the protective covers. On that lil board
that stands up like a "module" SIP, the ONLY active parts are an LM-139
Quad Comparator (SGS-Thomson variety with cerdip and -25 to +125degC
rating, so them guys know what they're doin) and a lone transistor. A
sprinkling of the usual diodes and passive discretes, of course, but the
point IS, it ain't no special sauce or any analog black magic, cuz there
ain't even no op amps, so if there IS any filtering it's of the lowliest
kind, since there is no active filtering possible on this board. I
traced the circuit out enough to know for sure this IS the module that
does the ion detection, cuz two of them comparators directly drive the
signals that say which cylinder is firing. This is EXTREMELY
encouraging, cuz if we can understand this technology, the circuitry to
implement it obviously is pretty dirt simple AND dirt cheap. As a result
of this latest intel, I am even more confident that after digesting the
available papers and summing up all our fractional wits, we're VERY
likely to get a workable DIY implementation. ION is beginning to smile
upon us, methinks. Maybe if we're nice to her, she's tell us her
secrets. B)

Gar