[time-nuts] Local Solar Time Clock

[Jim Lux]

On 1/19/14 2:00 AM, P Nielsen wrote:
> To Jim Lux. After you get it working, would you consider putting the details
> online, or selling as a kit?
>

Half coded.

I'll publish all the details..
It's pretty easy.. a Arduino, a clock, a wall wart to power it.  I 
haven't tried it yet (no clock to test with until the stores open), but 
I'm assuming that it's just a wire from the digital output port to the 
clock.  Might need a resistor in series.


The other burning question is "how accurate" does it have to be. The 
scheme I have now basically has a table of "rate" vs day of year (which 
I still need to calculate).

Right now, the EOT is changing almost 30 seconds/day, which implies that 
the clock could be some seconds off during part of the day (although 
"true" at noon).

Given the tens of ppm accuracy of the crystal = some seconds/day it 
seems that I want a bit better algorithm.
Rather than drive from a table, maybe actually calculating it. the 
Arduino is no ball of fire for floating point computation, but still, it 
doesn't have that much to do. It could be that I can just calculate the 
rate every second.

But then I have to differentiate the equation of time... and I haven't 
had enough coffee yet to differentiate the chain of sinusoids analytically.

>
>
> P Nielsen
>
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