"Morse" wrote in message
...

Thinking about it a bit more- the closest approximation I can come up with
would be four 30v zeners in a serial-parallel combo. Two zeners in series
with anodes together in parallel with two zeners in series with cathodes
together. This would drop 30.6 ish volts in either direction if I'm not
mistaken.

IIRC, a diac is like a triac with no gate - when it fires the dropped
voltage is a couple of volts only. This is unlike a zener.