I need to build a simple logic gate circuit such that when a single input signal or switch goes low it alternately activates one of three outputs as high. That is, every time it goes low the currently high output goes low and the next in the series goes high - cycling which output goes high between the three.
Years ago when I took an electronics class we used a program similar to CircuitLab. And I designed a very similar circuit. But I've lost that design and it was so long ago that I've gotten very rusty.
However, I can think of one way to build a circuit that would -almost- do what I want:
I could use a binary counter in combination with a 2-to-4 line single-bit decoder. (See the illustration on Wikipedia's decoder page.) The problem with that solution is it cycles between FOUR outputs. And my design requires that it cycles between only three.
As I said, I designed a circuit almost exactly like this years ago. And while the details are very foggy, I seem to recall that it was so simple that it only required one or more flip-flops (or latches) and a few other gates besides.