On Thu, 17 May 2012 08:13:30 +0100, "N_Cook" put
finger to keyboard and composed:

When I get back to it I will try a 72V zener over one of the Brown-out?
zener chain of 220/200V zeners ...

I would think that 420VDC would be required to "turn on" the series
connected zener pair. A 240VAC source would produce 350VDC, so ISTM
that these zeners would be sensing an overvoltage rather than a
brownout. That said, the overvoltage would have to be an extremely
large one (+20%).

- Franc Zabkar
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