Thanks Patrick,
This thing seems to do the same. The Variac is
unique in that he has a "Center Tap" and just controls
buck/boost to one side of the XFMR. All the load "I" is
going through the other side. Here is a functional
schematic.
The Manual is here:
http://www.ietlabs.com/pdf/Manuals/GR/1571A-%201582A%20Automatic%20Voltage%20Regulator%20Instruction%20Manual%20Complete.pdf I just have to find a place under my bench for him and
get it all plumbed in.
73
/Dan