In my opening salvo, I mentioned that through reading the forum on 4-20mA sensors, I came across posts that pointed this out, using Afref - in fact you were the standout in the discussions I read. Thank you for that, as it motivated me to read more and this topic and helped me to understand why this should be the application - over the past couple weeks.
I'll go ahead and do that, instead of postphoning. FWIW, the Mega is powered through the 9V charger - my plan is to use a Pololu to power the Arduino - one reason there are two open spots on the termninal block.
I know a little bit about the physics of crimping, and Im trying to help a friend who has a side business making large gauge wire harnesses - they have NIST calibrated gauges for the hydraulics, but not always easy to keep the operators looking at them. This system has LED's and couple buzzers when things don't work as well as they should - eventually will save data to a server for QC and post-signal analysis.
I've seen a couple posts where the designed user the Shottky to VCC and GND, and I will incoporate that, but will try to understand the why's so I can learn too!
Thanks to people like you Leo - again, I've seen your comments many times and even when its not something I was looking for, grateful people like you are willing to share their expertise.
-S