If you can't beat 'em, join 'em.   Following a discovery that the I am working on a revised design based on SN7407 level shifters.   (If you want a board from the the buffers work as expected, please PM me for details.)         Simple enough circuit but I have several questions.   First off: any problem with cascading the buffers this way? The idea is to have a switchable output between +5 (also serving as Vdd for the ICs) and an adjustable voltage which is derived from a low-drop