So I need another component then ?
I want to have the 'no current load' on the circuit being monitored - and ideally want to do it from the same supply as the circuit being monitored (which should be 5V).
Any suggestions on an Op-Amp capable of producing that from +5 only!?
The plan is as "CrossRoads" previously posted here: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1293425807/21#21
Finally making some ground on this - but yeh, he said single power supply there ( comprehension fail!).