Thanks Stan. All of these solutions are out of my comfort zone, that's why I asked for help. I know how to program in BASIC and have some experience in other languages. But NOTHING with systems-on-a-chip like Basic Stamp, Arduino, Raspberry Pi, etc. The cost of the Basic Stamp doesn't bother me, I was prepared to spend up to $200 to obtain a complete working device. But where do you get an RS-232 interface these days, and what kind of software would you use to communicate through it? Another thing I'm concerned about is the breadboard part where you wrote "a few resistors and capacitors." That isn't too specific, and I wouldn't know where to begin.
Re: the modules, I don't care if the solution is "Rube Goldberg-esque" as long as it works. I'll look into the ones you depicted in your post. They're not expensive, but i'm still not sure how to hook them together, or whether they'll really do what I need. Is the "bistable MCU" a one-bit storage system for the state of the footswitch in my example? I'm not an EE so all of these terms are foreign to me.
I can't be the only one who has ever needed to lock and unlock a "latching" target circuit with a momentary pulse. I guess when I posted, I was hoping that a circuit like this was commercially available.
