Effects switcher - how to prevent engaging two patches?

[Miyagi_83]

I'm not the best person to explain this, and sometimes phrases such as this do not translate well into other languages, but I'll give it a try.

Thanks for taking the time to reply anyway. Besides being a hobbyist guitar player and gear builder, I'm an English-language geek, so I'm keen to learn new things.
I decided to use this idiom because, other than for expressing gratitude, I've seen it used in situations when the speaker was being sarcastic, and by the tone of their voice and the look on their face one could tell they were saying, 'You're being silly'. So, I wanted to laugh at myself a bit 
Have a good one.

[Miyagi_83]

Ok, I've got another idea.
For this one, I would use three SR flip-flops (CD4043 or 4044 perhaps) which could be set or reset in any combination possible through a network of diodes, and their outputs would be connected to the three data pins of the CD4051 mux which would steer a logic "1" to the inputs of some other device, like the 74HCT373 wired in a manner similar to (the same as?) that in R. G. Keen's article.

Theoretically, it would offer up to 8 channels. Moreover, it wouldn't care about contact bounce and pressing more than one footswitch at a time would simply activate one channel which gets SET first.

Does it sound doable or am I being overly optimistic?

[Loudthud]

It is unclear to me what you are trying to accomplish. Do you want to control 8 relays or loops with three foot-switches ?

Please refer to any circuits in RG Keen's or Mr Elliot's articles by the numbers of the illustrations in those articles.

Side note: Figure 8 of Mr Elliot's article shows how a resistor is used to make a good logic low when diodes are used as an OR gate. You don't want CMOS inputs to be floating around causing circuits to intermittently malfunction... and they would seem to magically fix themselves when you tried to measure logic levels with a DVM which would pull the floating input low.

[Miyagi_83]

It is unclear to me what you are trying to accomplish.

Ok, the fact that English is not my first language and that I'm a bit hyperactive, which will make me say something twice before I actually think about it, might have been contributing factors here. Sorry about that.

Let's go from the beginning.
Because, being a guitar player, I like different tones, over the years, I got myself a bunch of effects units to spice up the music I sometimes play. In order not to tap dance around my pedal boards, switching effects on and off, especially during a song, I started thinking about an effects loop switcher which would allow me to activate certain pedals and disengage others at the click of one footswitch.
There are, apparently, a number of ways to achieve that, including microcontrollers and CMOS digital logic. Some ideas have been provided by RG Keen and Rod Elliott in the articles I linked in the first post. Now, for a theoretical analysis, the number of pedals or channels is unimportant.

The point of this thread, initially, was to come up with a CMOS-based system which would prevent the activation of more than one channel if more than one switch were pressed. I think this goal has been achieved, but I'm still trying to refine the idea.

I'll get back to you later because now I've got a couple of things to take care of. Stay tuned.

[Miyagi_83]

Side note: Figure 8 of Mr Elliot's article shows how a resistor is used to make a good logic low when diodes are used as an OR gate. You don't want CMOS inputs to be floating around causing circuits to intermittently malfunction... and they would seem to magically fix themselves when you tried to measure logic levels with a DVM which would pull the floating input low.

Again, I'm really grateful for any lessons I can learn. I can't stress that enough.

It is unclear to me what you are trying to accomplish. Do you want to control 8 relays or loops with three foot-switches ?

Please refer to any circuits in RG Keen's or Mr Elliot's articles by the numbers of the illustrations in those articles.

As far as my last idea is concerned (SR latches and 4051 mux), I was referring to the diagram in Mr. Keen's article shown here. Later, upon further consideration, I realized that, in the configuration I had in mind, it wasn't necessary. What I came up with is on the diagram attached. A lot of parts have been omitted for clarity.

You can have up to 8 footswitches to control one 4051 chip. These switches are connected, through diodes, to the SET and RESET pins of three sections of the 4044 chip to force a "0" or "1" on the output of the correct section to make the 4051 connect its COMMON IN/OUT to the desired IN/OUT pin, as per the function table.
With the COMMON IN/OUT pin of the 4051 connected to V+, one could control transistors, for example. The collectors of those transistors could be connected to DIP switches which might serve as presets, in the most crude form, tying relay coils of individual effects loops to the collector of that transistor.
I think that this helps to tackle the following problems:
1. switch contact bounce
2. activating more than one channel after pressing more than one button / footswitch
3. excessive number of ICs
Of course it comes at the price of the number of diodes necessary, but you just can't have it all, can you?

Can you see what I mean now?