I built one from scratch last year for my S10 Blazer and pickup. It
works fairly well with and old P133 laptop that I picked up for $15 a
a local swap-meet. All in all, I probably spent around $40 for the
computer, the Elm 322 chip and some odds and ends. And I'll probably
use the laptop for other stuff. For me it wasn't just the low cost of
the unit it was the challenge of building something.....
Below is an excerpt from a posting I made on the scantools.net
Aside from the laminate and the PCB artwork offered on the
scantools.net website, I acually made the entire PC board myself. I
printed all the images on standard white paper with my 12 year old
Wang laser printer (with the toner setting on maximum). I then ironed
(literally!) the reverse version of the image directly to my freshly
cleaned copper-clad PCB. Cooked toner makes a pretty good resist.
Even at 300 DPI the thru-holes were pretty clean.
After wetting in tapwater, I was able to rub off all of the paper
fibers. I chose to drill all the holes at this point (before
etching), to prevent any traces from being ripped off the board by the
drill bit. This worked out well.
I then etched the whole thing in a Pyrex baking dish. Not bad for
mostly kitchen work! Light buffing with some emory cloth took all the
toner resist off and polished the traces for soldering.
Later, after I had installed all the compnentrty, I had a heck of a
time with the listed gain of a number of transistors. Be careful
here. Compatible parts aren't always. As I was using scavenged parts
(nearly everything but the ELM 322 chip), I only had myself to blame.
After some help from the guys on the website (Thanks Vitaliy!), I was
able to get thing working properly (replaced some transistors with
higher gain units).
I haven't checked the website recently to see if the new version of
software is out (the one with data logging), but there are a number of
free or next to free programs that will work with the Elm
Now I'm waiting for my first SES code to appear....... 8^)
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