Logical inputs with one a 50% delay from the other input. This let the transistors turn off and on according to logic 1 or 0 input. I think this is a switching power supply type of design which I used to make this circuit. Had to modify the original circuit to work with this circuit. I learned quite a bit from this which was my goal for doing this. I think that it is working the way it is supposed to but I am not sure.
