Just so you have the full picture, the next step is to have 1 cv in 8 pots and 1 out, and the arduino sequences between which of the pots to apply (or none) so that the outgoing CV can be controlled via the computer.
Even longer term I'm hoping to do 3CV in 3CV out, 8 pots on each track, tempo pulse out, LED's being lit up etc etc.
I'm having some difficulty picturing your circuit. You should include a simple sketch.
If the power level is low you can use a multiplexing chip rather that a batch of relays.
The chip will be cheaper, smaller, faster but not handle much current.
It's for analogue modular synth. I want to keep all of that voltage separate from the arduino, just use the arduino as the switching mechanism.
Only one relay would be open at any one time (I'm assuming if I opened more the current would flow the path of least resistance anyway).
This example is just 3, the first real one would be 8. So the idea is you set the 8 dials to the resistance you want, then on the computer (or arduino) you setup the sequence of steps and away it goes. The idea is you could then have infinite combinations of those 8 resistance values, that can then be reordered on the fly. Most sequencers go 1-2-3-4, or 4-3-2-1 etc (in steps). I wanted something I could automate from my computer.
And this was my first sketch when I thought I needed to be using optoisolators or analogue IC switch matrix things.
My concern with optoisolators is any latency, I need on off to be as fast as possible. My concern with IC switch things, is I need the other circuit to be as untouched as possible.
Hence my thought process coming back round to regular relays.
You may find that the open/close time of those relays (which are, after all, mechanical devices) is too long. Or not: it might be necessary to determine that by experimentation.
You can probably get away with using analog switches/muxes like the 4051: the small "on" resistance probably won't screw things up for you. But, again, you may need to determine this empirically.
If you need to run the analog switch at a higher voltage than the Arduino's 5V Vcc, there are simple solutions for shifting the logic levels.
I think I might need to order a selection of options and see what comes of it. I have optoisolators already (for some reason or other).
I did have a really crazy question.
I need my pots to go from 0% to 100% resistance ideally on both 5v and 12v. Can I do that with 1 type of pot? Which Ohms value do I need to get linear 0-100% resistance? (this might be a totally dumb question, i apologize, pots ohm values always mystified me)
No latency that you will ever perceive. These devices typically go at over 1MHz, that is 1uS delay, Superman couldn't detect that.
I opened more the current would flow the path of least resistance anyway
No that is one of those stupid things people get taught that is not true. Current will flow down all available paths, the bulk of it flows down the path of least resistance but by no means all of it. Having a resistor with a voltage across it will allow a certain current to flow. If you put an other resistor one hundredth of the value across it then that will cause one hundred time the current flow in the first resistor to be in the second resistor. However the first resistor will still have the same amount of current flowing through it.
