I guess maybe what I need to figure out is if there is a more efficient way than to use shift registers to get this particular project accomplished.
I am presently having a shift register go high when a certain condition exists. However the output can exist at several voltages (and even as a contact closure).
Here are the voltages I wish to have the arduino trigger to some sort of an external chip. Contact Closure, 5VDC, 12VDC, or 24VDC ... I figured I could use some transistors and another shift register to switch activate the correct transistor, but there has to be a better way. The output will be going to a binding post (banana plug).
Is there a chip that could self regulate the voltages?
The kicker also is I need 24 selectable output banks, each one selectable from any of the 4 combinations. Surely I could do this with fewer connections like I am thinking. Any ideas are appreciated. Let me know if what I'm talking about doesn't make sense.