erik malund wrote:

Still a whole lot better (10Mohm) than clipping the 'ol ground lead on.

Suprisingly little in the very small signal conditions we tend to hunt for problems in !

How does the thang you mentioned truly float (transformer? opto?)

Yes, transformers and optos. The front end of the scope is replaced with the magic box, which provides the necessary gain stages, Analog Devices make isolation amps whcih you can roll your own with. Invaluable.

Steve