Automate Tonepad Sinamp GT2

[william]

I'm getting back into Pedal building after a few years away.  I built myself a tS8 pedal a few weeks ago for practice.  I've mostly been building tube amps.  I'm revisiting my build of the Tonepad GT2 which I never "finished".  I got a box from Radio Shack to house it in but it didn't quite work and the Pots I got fit weirdly.  I'd like to rebuild it to work better and be more interesting.  To this I've gone back and looked at a daughter board I was thinking of making for using a PIC to control it.  I've got the switching using three CD4052 ICs.  I had originally planned to use LM1972 to control the pots.  I'm now not sure that the IC will work due to the voltage requirements.  I tried finding some digital pots that can take 9v at 100k but was not able.  What IC's have people used for replacing 100k pots?

[Vivek]

I had originally planned to use LM1972 to control the pots.  I'm now not sure that the IC will work due to the voltage requirements. 

Please help me to understand what is the issue with supply voltage ?

The spec sheets say Vdd - Vss should be between 4.5 to 12 V

and max Vdd-Vss is 15 Volts

Isn't that acceptable for your application ?

https://www.ti.com/lit/gpn/lm1972

[ElectricDruid]

+1 what Vivek said. That chip looks fine to use at 9V. What's the problem?

The examples in the datasheet seem to use +6V and -6V supplies, and expect the logic to work 0V to 6V, so it migth be eaiser to run the thing on a +/-5V supply so the PIC can run from 0-5V. Although if you only had 9V, a PIC is happy on 4.5V too. However, this same issue of the logic supply and the analog supply turns up on the 4052s as well, so you must have dealt with it.

[william]

You appear to be right.  I'm not sure what I was thinking yesterday.  I did the initial schematic about nine years ago and spent about two hours looking at it last night trying to remember why I chose the things I did.  I must have assumed myself nine years ago was an idiot.