Or a slightly easier to follow version is here:
http://atarihacks.cjb.net
Look for Video and Falcon adaptor. If you wonder what the differences are for I think the 68ohm resistors are just to adjust the contrast or something. Don't worry about it, not having them won't break anything. Combinations of M0 and M1 select which monitor is attached. I use a toggle switch to select VGA or RGB on boot up.
