Hey Mark,
Thanks for the link. Cool info to stash in my file of goodies. The circuit they are referring to in the pages you pointed out, is for an "arc ok" or "ok to move" signal. My Thermal Dynamics machine has a built-in "ok to move" dry contact to signify arc transfer. What my machine does lack, as I'm sure you have gathered is the voltage divider circuit. In my travels, I cam across a cool thread on the Parallax forum...check it out:
http://forums.parallax.com/showthrea...Height-Control
Head to post #17 and take a look at the schematics. They have been my wealthiest resource to date.
Look forward to all of your input,
Chris