First let me just I'm a total newbie to electronics, but I would like to progressively learn how computers work by building the little components with the small parts, and then work up to the ICs once I understand how to make rudimentary versions. I'm trying to make a 1-bit multiplexer out of transistors and resistors, maybe I need more components than that. I'm not 100% clear on the resistance values I need for a 9V battery and bread board either. Was wondering if anyone could give me some pointers. I've attached a schematic I've come up with to try and implement those ANDs and NOT to create a 2 to 1 selector. I'm suspecting that maybe the ground is just draining the circuit here, but my troubleshooting skills here are in their infancy as well. I don't know how to confirm it or what I have to do to make it behave in the intended way. Thanks to anyone who has any pointers or resources.