Excellent, but I would take you up on point 8 though. Did you mean that the current from generator A could return through the return of generator B via the earth? If so how could it jump the isolated winding of B and then back across the isolated winding of A. If this is not what you meant, could you offer a little more explanation.
An experiment would clear up all the disagreements, unfortunately which of us is going to get the opportunity? But if someone does I'd suggest using a isolated mains transformer for the Scope supply.
Adrian.
