RBob/Dimented24x7 have been guiding me along and it sounds like i have a good option cooked up now that will allow me to make somewhere between a square and sine wave for the O2, which is what happens IRL, which is exactly what i want... and with the ability to adjust frequency independantly of duty cycle, which meets my initial requirements. it would also seem that i can now change the center point of where the "O2" switches, which will allow futher fine tuning....