> > All this talk about clocks and 50Hz/60Hz mains
> > timing and getting crystal clocks accurate just
> >
> > Using mains sync is probably the best for accuracy,
>
> I use this circuit as an accurate and very low power long-
> term back-up if mains goes down or is removed during
> transport. You can pick up a kitchen clock for $2, take the
> small PCB out of it and unsolder the coil connection. (The
> coil, btw, can be driven by reciprocating PIC o/ps through
> a 390R resistor so the clock movement isn't a write-off).
> The PCB puts out an alternating 0.5Hz on each of the two
> pads where the coil was. Pick either as the 0V

All this discussion has me rethinking my sunrise/sunset clock/controller.
So far I'd been happy with the 32khz crystal but I haven't run tests more than
24 hours yet and the target location isn't going to be a well temp controlled
as my test bench.

Did we finally agree that a couple of big series resistors and a 5.1 zener
was the safest line voltage reducer? I think I have some 1 Mohms in one of
my junk boxes.

So what do you think of the idea of counting line frequency for the primary
timekeeper with the 32khz as the backup? I already have the 320 Khz and
adding 2 junkbox resistors and and zener is no big deal.

Thanks,

BAJ

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