[time-nuts] Local Solar Time Clock

[Jim Lux]

On 1/18/14 2:25 PM, P Nielsen wrote:
> I am looking for a physical clock (not software) that will indicate local
> solar time. IOW when the sun is at its highest point, the clock would
> reliably read 12:00 throughout the year.
>
>

So it needs to take into account the equation of time?

there's probably some exotic all mechanical geared scheme for this in 
some $20k pocket watch..

>
> Is there a commercial product or kit available for this?


I know you're not interested in a software solution, but my approach 
would be to drive a conventional electric clock (1pps ticks) with some 
logic that implements the equation of time.  It would be pretty easy to 
have a table that sets the divisor from the clock to the 1pps and slowly 
changes it above and below the nominal rate so that the clock reads noon 
at solar noon.

I did it back in 2004 using a HP 3325 replacing the 32 kHz crystal in a 
24 Hr clock to build a Mars clock.


It kind of depends on what instantaneous accuracy you need, too.

the deviation is on the order of 15 minutes, but do you want the error 
of your clock to be a maximum of 1 second or 10 seconds or what...