> Is there a reason why a MOC3020 opto-triac couldn't be used ?
>
> Or is there an alternative opto > 80V ?

Even a 300V opto would be marginal there.

However, you should have no problem tapping down the high voltage with
a resistive divider.
Issues are that gate current can be quite high so that a divider that
is always on could dissipate excessive energy. Adding an extra
transistor or two to translate from opto circuit to gate drive would
allow good drive with low average power dissipation. I can supply an
?MPSA43? which would work there if you want one. (MPSA42 is common.
MPSA4* is it's little seen cousin with an  extra 100 volts rating. (*
= whatever it is I've got - I think it's MPSA43).



         Russell
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