Road Rage 2014 - 12v Zener?

[PhiloB]

I'm building the Quadrovibe.  I ordered the parts based on the Quadrovibe BOM.  I etched the Roadrage 2014.  It calls for the 12v Zener where the other previous RR had none.  Can I just leave it off?  I'm using the RR for +18v.
I have a 9.1V Zener.  But no 12v.

[PhiloB]

Turns out I do have a 12v Zen - 1N4742

[madbean]

FYI, you can leave it off if you are sure you will never plug in the wrong power supply. The Zener prevents too much voltage from going to the charge pump and damaging it. The charge pumps all have different voltage tolerances but 12v satisfies all of them, more or less (the MAX1044 is 10v max, I think). 9.1v is also fine. I picked 12v because there might be times when one wants to turn 12v into 24v, say with an LT1054.