It just occurred to me that as I'm tweaking the Gauss Drive and reducing the value of R16 lower and lower I may get to the point where I need some negative value resistors. I've gone from 4K7 to 1K, thinking of trying 100R so where do I go from there? Where can I get some -1K resistors? It seems for some bizarre reason that Tayda don't stock them. Crazy!