On 1/19/14 1:51 PM, Tom Van Baak wrote:
So, periodically, one would need to reset both the analog clock AND the
Arduino clock to bring them back to proper alignment.
I suppose that periodically, one could compare "number of ticks sent"
with "UTC + EOT offset" and try to compensate (by dropping ticks or
adding them).
And then you'd have a GPSDST (GPS disciplined solar time) clock...
While you're at it, add a rotary switch and allow the (JPL) user to select
which planet's solar time they want to display. Since there are now only 8
planets you can also do it with a 3-bit configuration switch (now you know the
real reason Pluto was demoted).
If your project works ok for the earth clock, the next step is a jaw-dropping
array of 8 (9) clocks in a JPL lobby showing the differently ticking solar time
for each planet. Use 24h clocks for best results. They can be had from
www.clockkit.com, an excellent source of DIY quartz clock parts.
You have divined my ultimate goal..Display local solar time for every
lander, for instance.
Except at work, I'd get a bunch of 3325Bs (since we have pallet loads of
them around), driven from the maser based reference, and have a PC
sending GPIB commands to them to adjust the rates.
Handy to have a source for 24hr clock movements. Last time, I bought a
couple MFJ 24 hour clocks at the local Ham Radio Outlet..
To be honest, one of the interesting challenges is dealing with power
failures in these kinds of systems. The Arduino is not a low power
device..(at least not in the AA battery for 2 years sense).
So, do you run the whole thing off 12V (which is what I'm going to do)
and a float charged battery OR do you do something clever like detect
when power is failing and save it in NV storage, then when you come back
up, you send a bunch of clock ticks real fast to catch up.
Our lobby isn't that big at JPL.. I'll probably hang them down the hall
outside my office or something. I had the Mars clock outside my office
(with a 50 ft coax to the signal generator under my desk) for about a
year before I had to take it down in the annual "clean everything up"
festival.
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