Designed these using PSPICE......too much fun....
(more is done on paper but you guys don't want to see my awful hand writing and drawing skills)
The first two are both logic diagrams for 3x8 decoder circuits, but one uses an IC that has open-collector outputs.
The third one is a logic diagram for a 8x1 multiplexer circuit.
I totally understand! That's where you put the multiplication divided by the number of numbers squared and you use trigonometry to Pythagoras the theorum.
It really isn't that complicated. Everything has a process. You don't just decide you want to build something then do it. You need to know how many inputs and outputs it needs first. Then you write up a truth table with the resultd you need and want. Then you draw karnaugh maps for each output. Finally, the design can be drawn. Simulate it and test the results. And last.......build the actual circuit.
It was a good thing that I posted this thread. I had printed this out once I finished it but I forgot to actually grab the paper before leaving for class. I got to lab and was looking for it when I realized that I never grabbed it from my printer. So I opened this up really quick on a computer in my lab and then took a screen shot to print it out. =p