Return of the diy_EGOmeter (YES, it's finally ALIVE!!)

[garfield at pilgrimhouse.com]

On Tue, 14 Apr 1998 18:15:02 +1000, David Chambers
<dchamber at pronet.net.au> wrote:

>This sounds great. Do you need anything done in the way of a user
>interface to the output of this?. Ie a processor circuit some LED
>displays and software to run same.

Hey Dave.

Yeah, we discussed this earlier, and because some will be logging data,
while others will want to incorporate these lil beasties into their
custom ECUs for such things as WOT closed-loop, etc., and some will just
wanna build a visual meter, what I was assuming we'd do is start with a
basic "interface", like what NTK sells. Then, depending on what people's
application is, the rest can be layered atop that "interface".

I'll give ya an example: whilst Horiba does a two-segment piecewise
linear curve to completely linearize their output over the AFR range
(this, for example, is just one of the myriad tid-bits Frank passed
along to me), NTK has chosen to simply output their Ip pump current
values, which ARE directly relatable to AFR, but the curve of Ip vrs.
AFR has two diff. linear slopes depending on lean or rich side of
stoich. That's the basics of how the instrument/circuitry works, so they
just pass that on out to the user. This makes best sense if you're gonna
be tieing a micro to the interface anyway for control or gui purposes,
where as Horiba's full linearization DOES allow one to hook up a data
logger directly to it and go instantly.

But all's I'm gonna provide is the schematic & ops of the basic
interface, so it'll look a lot like the NTK box, concept wise. That
seems to be the most versatile and all-round best way to go. From their,
the factions of usage might coagulate around further ideas for the
additional layers, but we'll all decide that as a group or groups, like
everything else like that.

That's my take on the situation; once the egg's been laid, everybody's
free to hatch it which ever way they want. BTW, the schematic will be
copyrighted by our non-profit aviation group "AirSIG, Inc.", and freely
available to anyone to use, eXcept for commercial eXploitation without
written permission. This is done solely to keep someone from sucking up
on our labors, and milking it as a cash cow. That's also how we've
handled the EFI & IGN circuits our aviation group has developed for our
eXperimental aviation engines. Kinda like the Free Software Foundation
idea that gave us Gnu, if you're familiar with that.

Garfield