Hello I would like to add an input for expression pedal on my effect pedal for guitar.
The expression pedal is a potentiometer of 10k (generally) controlled

with the foot.
This pedal will control a 50k potentiometer (if the exp pedal is not on, the user can use the normal pot) there will have a switch to choose between exp pedal or normal pot
I do a schematic with vactrum vtl5c3/2 but it's expensive. If someone know an Ic to replace this ...
I post the schematic and tell me if there's mistake
best regards
franck