15v Zener - can I use a 16v instead?

[rfdvrcasey]

I'm putting together the Archibald and just noticed that I didn't order a 15v zener but I do have a 12v and a 16v.  Can I use either of these without any issues or should I just order a 15v?

[Drew Hallenbeck]

The 15v Zener is there as an over-voltage protection device to protect the charge pump. The max input voltage for the 1054 is 15v (hence the 15v Zener).
You could probably get away with using a 16v Zener in most cases. Typical power supplies have outputs for 9 or 18 volts. If you accidentally connected to an 18v output on your supply, the 16v Zener would shunt the voltage to ground just as well as the 15v.
However, some supplies also have 12v, 15, or adjustable 9-18v outputs. Some of these situations may allow for voltages above 15 but slightly lower than 16 which could cause trouble.
The circuit is designed to operate at 9 or 12 volts so I'd say definitely don't use the 12v Zener or you'd never be able to use it at 12v.
In most cases, you'd probably be okay going with the 16v Zener but you're taking some risk.
Another thing to consider is, the circuit will operate just fine without the Zener diode. You could order the correct part and add it later as long as you're real careful not to connect to anything other than 9 or 12 volts in the meantime.
(might be a good idea to make sure you're using a socket for the charge pump just in case)

[rfdvrcasey]

Thank you, I have a much better understanding now.  I'm going to build it as is without the zener until I order components again at which time I'll put in the correct 15v.