Antonio,
it is quite easy to make an external circuit that uses a 32kHz xtal
and divides
it down to siderial seconds. It is also easy to drive most analog
quartz clock movements from
an external circuit.
Just what signal do you need? What frequency? and what does it drive?
(an alternate polarity
quartz clock motor?)
It can also be done with a micro if you have the skills.
cheers, Neville Michie
On 16/05/2011, at 8:02 PM, [email protected] wrote:
The background of my request is an OT story. Just to mention
briefly, I already
have an ordinary (non-radio-controlled) clock machine which turns a
miniature
torsion balance in a sealed glass vessel. It runs on a single AA
battery. No
extreme accuracy needed. I wont to modify the rate to sidereal, and
might have
to replicate the setup too. I figure that the solution I should
pursue is
getting the "odd" crystals.
Now it is clear to me that I have to explore two options, a)
contacting a
crystal manufacturer, b) modifying 32768 crystals.
Thanks,
Antonio
[email protected] wrote:
does anybody out there have any ideas as where to find a 32859Hz
crystal
(1/
2 that value would be better) to be used to replace 32768
crystals in
ordinary clocks? I think that 32768 crystals cannot be dragged
that much.
I've already read the JimLux article somewhere on the web, but I
would be
pleased finding a simpler solution. Also, I already have
computer programs
that show sidereal time.
I think it depends upon what you mean by "ordinary clocks".
Most of the recent wall clocks I've seen are battery powered
(single AA) and
resynchronize nightly via WWVB.
If you want sidereal time, you won't have anything to synchronize
to. What
sort of accuracy are you interested in? If you want reasonable
accuracy,
you
will need an external signal. (You can provide power over the
same cable.)
My straw man would be to send 32859Hz down coax or twisted pair
and feed it
into the xtal-in pin on the clock chip. I'm not sure how to set
the time.
You can cut the lead to the antenna to make sure it doesn't sync
to WWVB.
You can make 32859Hz from a PIC (or any micro you like) running
off any
handy
frequency. Given that this is time-nuts, I'd suggest 10 MHz from
a GPSDO.
It might be simpler to dump the 32KHz and WWVB chip and drive the
motor
directly from a 1 PPS signal. Just use a sidereal second rather
than a
normal second.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/
time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
