Ted S posted:... I was prepared to spend up to$200 to obtain a complete working device.
I'm surprised you haven't been contacted by someone via private-email or whatever! An Arduino aficianado ought to be able to whip this up (the programming part) in less than an hour. The hardware would be maybe $10 for an Arduino module, a wall-wart DC power supply, and a few discrete components/connectors.
...But where do you get an RS-232 interface these days, and what kind of software would you use to communicate through it?
There is an abundance of USB-to-RS-232 converter cables, dongles, or what have you for next to nothing. Then you'd use a "terminal emulator" program. I see that Hyperterm is no longer available for Windows 10 but there are "free" alternatives. So when launching the Terminal Emulator program, it should allow you to set the "baud rate" of the adapter cable, then hit Carriage Return a couple of times and you should be talking to the BASIC command-line interpreter!
...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.
Right. It's just that these digital/microcomputer chips are electrically "fragile". When attaching them to the real world like a foot-pedal switch with several feet of cable or what have you, you need to give some thought to protection from glitches, spikes, noise, and other nastiness. Likewise, the digital signal are generally not robust enough to drive a relay which (as I understand it) you need to momentarily "open" the secondary circuit. Hence, I suspect you'd need to add some "stuff". But you're correct that this would need additional clarification albeit the actual cost would be modest - $1 or $2.
...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.
Right. In the same way that you use the variables A and B in your BASIC program, you need memory to know which state you're in so that you know what to look for to interpret a change of state.
...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.
Upon further reflection, I think the general concept has several applications in O-gauge trains. I was thinking about some earlier OGR threads about things like two trains or trolleys that alternate running on the main loop and benefit from time-delays to make the action more realistic.
OK, while I still think the Arduino approach is the way to go, I'm assuming this is not in the cards.
Stand by - I ought to be able to cobble together some kind of relay/timer module concoction that does not require assembling and soldering a bucket of tiny electronic components.
