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I have two control voltages(CV1,CV2). Both represent the same data, but one in linear and the second one is exponential response. I would like to have a potentiometer to blend from CV1 to CV2 so I can smoothly transfer from exponential to linear mode before feeding it further to IC. I'm pretty sure I could do it with a dual potentiometer wired up so that R increases for CV1 while decreasing for CV2, before summing them in op-amp. I hope to find a solution that would work with a single potentiometer. Is there a term that describes this kind of function that I could read upon? I'm not even sure what Tags to use in this question. Thank you!

Control voltages are audio rated so 20kHz would be the maximum frequency they would operate. And Voltage range is 0 to ~+2V. Ideally it will be -30mV to +2V, but I guess the negative can be removed if it complicates the solution.

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  • \$\begingroup\$ Error budget - accuracies and resolution and range for both signals need stating. \$\endgroup\$
    – Andy aka
    Feb 8, 2021 at 9:51
  • \$\begingroup\$ Have you tried putting CV1 and CV2 on opposite ends of a potentiometer and using the wiper for the blended signal? \$\endgroup\$
    – Andrew Morton
    Feb 8, 2021 at 10:14

1 Answer 1

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Consider this:

enter image description here

Provided the source impedance is low enough to not be disturbed by the load of the potentiometer R. The input impedance of IC should be high compared to R. If not it will affect the linearity of the transistion. Remember don't let significant DC current through the wiper of a potentiometer - it will degrade and produce noise.

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  • \$\begingroup\$ Thank you. Somehow I thought this would be much harder. \$\endgroup\$
    – somerandomusername
    Feb 9, 2021 at 8:57

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