allanhurst:
My diagram pedal3 in the next post makes these points clearer - but you can get away without the external opamps.
Sorry, I just saw this. Don't know how I missed it.
Could I use a single LM358P (dual opamp) for both sides?
allanhurst:
LED displays take a fair bit of current - maybe a LCD?
I looked at an LCD, but am space constrained. I really only need 2 characters to display the preset number. Do you know of a small LCD which plays nicely with Arduino? I saw the 128x128 ones, but they're too big.