Overvoltage protection

Just was thinking about overvoltage protection at the CV inputs and had a simple solution. What if germanium diodes were used as clamps (Ge diodes have a ~.3V\ diode\ drop,\ Si~.6V) , but then an additional germanium diode was used to bring the AREF pin down to 5v - 1 diode drop? There would be two problems as I see it:

1. Not sure if the code currently references the AREF value. I know that you can disable the function of that pin.
2. More importantly, all of the pots are connected to V+ so they wouldn’t be scaled appropriately. This would necessitate a board redesign with the pots as voltage dividers from 0v-~4.7, by using the voltage at AREF instead of V+…

And I still think there must be some way to use zeners and avoid the voltage drop issue altogether…

#2 should protect against negative voltage swings as well?

I don’t know how nonlinear this is going to make things… but it seems sound to me… I believe I have some zeners on hand, and I could set up a little experiment.

#2 does seem to work as expected. An additional current-limiting resistor might be needed to avoid a situation where GND is sinking all the current it can from the source… I’d think this would generally be accounted for in a design, but one can never assume…