Does anyone think it's possible to have a form of multiplexed analogue resistor decade counter, that can be recalled like a digital pot', but making use of up to 500K + in 20k increments, and use them in series parallel depending on the resistance being called? Essentially a programmable carbon pot? I suppose in doing this, you wouldn't need a carbon pot, but it's useful to me in other ways.
Regards,
K
Please make a schematic of your proposal so we can understand.
I only see it possible with relays. Otherwise you fall in trouble with the power supply of all kinds of MOS switches.
What about the use of bi-stable/Schmitt switches? CD4066 or 40106 to switch in the resistors, and the power rail separate. 40106 could switch 6 x 20K and will only need 4 of them, leaving DPDT switching for the other 4 spare drivers.
This would be a lot for just one pot vale, though...
Is there any way to call upon resistances up to 500K without the need for so many IC's??
I've seen one guy do it with midi, but there's a lot of adaptation to another circuit. I want to build it from scratch into something like a volume pot that can recall different pre-set values, but essentially control all pot's in the circuit like this!
Volume controls are ALWAYS logarithmic pots because our hearing sensitivity is logarithmic.
Will it be an adjustable series resistor or be used like a potentiometer?
If all the wipers were adjustable would it look like this?
I know, but it's the value of the pot that want to change! Just by putting a 100K resistor over lugs 2 and 3 as a temporary pre-set measure, then back to using the pot as normal.
Regards,
K
Thanks for your reply, it's individual parts of a circuit that I want to control with User pre-set values if that makes sense?
No, it makes no sense. Draw a schematic diagram.
Write-Up: Adding MIDI Control to a Guitar Effects Pedal found this. Only ever seen the video
If I'm still interested at the end of the day after celebrating 4th of July, I'll take a look at that post.
Good luck with your project.
Please don't go out of your way 
What I did was replace existing analog pots with digipots, then I connected separate analog pots to an Arduino to provide a mechanism for user input and override.
Why can't you just do the same? Have digipots for your 500k resistance and control it with in 20k increments? You can use an analog pot for user input, or any other type of input mechanism.
For recall, I used MIDI, but a different type of input could be used to trigger recall.
What exactly is it you are trying to accomplish? In other words, what's the project you are working on?
Just checked all the pot' values, and the highest I'll be using is 500K. I'd want to control up to 6 pot's, though. I realise the 20k incrementation is a bad idea, because the different values would have different travel to reach maximum. Not that it's necessarily a bad thing, but would want complete control over them. There's also other features I've seen that I'd like to add like an LED ring as the pot rotates.
I have pretty much no guidance, so all is welcome.
Regards,
K
It’s tough to provide guidance when you still haven’t explained what your project is.
What exactly is it you are wanting to accomplish?
I'm essentially trying to achieve what you have, but with up 6 pot's with varying values. In the simplest terms, I want to make a circuit that can recall store and recall presets with visual feedback. There is a dual gang pot that needs to be no more than 500K and 250K.
It's to be able to control gain tone and volume, but for example; the Klon has a dual gang pot in it, so would need to control both at the same time.
What is the maximum you can get out of a digipot?
Regards,
K
So are you trying to add preset capability to a Klon then?
Or are you building your own effects pedal from scratch and want to add storing and recall capability to it?
There are a ton of different digital potentiometers out there, I don't see why you can't just use 6 of them (or some with multi channels to reduce the number of ICs needed).
The stacked knob isn't an issue, it would just be two digipots in your project. Why would you control both at the same time?
You could still use the dual gang, stacked, analog pot as the user input control as it's just two independent potentiometers in one housing.
Are you describing a stacked pot with individually adjustable concentric shafts? Otherwise, what would be the advantage of the two potentiometers as they would both have the same value?
Yeah, I think he's talking about a stacked pot with independent shafts. This is pretty common with guitar controls and effects controls due to limited space ... Especially with volume and tone.
It's tough to tell though, as I still don't understand what exactly he is wanting to do. Maybe a language barrier?
A picture would help tons too ...
Yes, to all of that. It's not clear either if the end result is a potentiometer or just a variable resistor.
