Re: [time-nuts] World's most precise.... wall clock

[Bob kb8tq]

Hi

The gotcha here is that if you want accurate *time*, you are better off using
the sawtooth corrected output from a (good) GPS module rather than a GPSDO.

Bob

> On Mar 3, 2021, at 6:20 PM, djl  wrote:
> 
> Hi John:   What's the cost of the CSAC GPSDO? I'd ask directly, but the exact 
> device specification seems a bit murky.
> Thanks
> 
> On 2021-03-03 10:34, John Sloan wrote:
>> I’ve built several small home-brew NTP servers using a Raspberry Pi,
>> a GPS receiver, and an LCD display. Most of them are desk clocks.
>> My favorite one (and the biggest money sink) is a mantle clock in my
>> living room that incorporates a chip-scale cesium “atomic clock”.
>> Photo: https://flic.kr/p/2kqoHC7
>> Blog article:
>> https://coverclock.blogspot.com/2017/05/my-stratum-0-atomic-clock_9.html
>> Git repo: https://github.com/coverclock/com-diag-astrolabe
>> --
>> J. L. SloanDigital Aggregates Corp.
>> +1 303 940 9064 (O)3440 Youngfield St. #209
>> +1 303 489 5178 (M)Wheat Ridge CO 80033 USA
>> jsl...@diag.comhttp://www.diag.com 
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> 
> -- 
> 
> The whole world is a straight man.
> --
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> VOX: 406-626-4304
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Re: [time-nuts] World's most precise.... wall clock

[djl]

Hi John:   What's the cost of the CSAC GPSDO? I'd ask directly, but the 
exact device specification seems a bit murky.

Thanks

On 2021-03-03 10:34, John Sloan wrote:

I’ve built several small home-brew NTP servers using a Raspberry Pi,
a GPS receiver, and an LCD display. Most of them are desk clocks.
My favorite one (and the biggest money sink) is a mantle clock in my
living room that incorporates a chip-scale cesium “atomic clock”.

Photo: https://flic.kr/p/2kqoHC7

Blog article:
https://coverclock.blogspot.com/2017/05/my-stratum-0-atomic-clock_9.html

Git repo: https://github.com/coverclock/com-diag-astrolabe

--
J. L. SloanDigital Aggregates Corp.
+1 303 940 9064 (O)3440 Youngfield St. #209
+1 303 489 5178 (M)Wheat Ridge CO 80033 USA
jsl...@diag.comhttp://www.diag.com 


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--

The whole world is a straight man.
--
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304


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Re: [time-nuts] AN/URQ-13 question How long

[Bob kb8tq]

Hi

Best guess based on similar gear would be “ 3 to 12 months” to stabilize. 

Bob

> On Mar 3, 2021, at 4:40 PM, paul swed  wrote:
> 
> OK the AN/URQ-13 is all buttoned up and powered up and working well. A
> dangerous statement to be made on Time-nuts. That said 5 XE-11 from what I
> see.
> That said consumes about 5 watts.
> But since the units been off for at least 15 years and heavens knows how
> long before that. Any thoughts on how long it might take to stabilize days
> weeks months. Its pretty stable as is just wondering.
> Regards
> Paul
> WB8TSL
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[time-nuts] AN/URQ-13 question How long

[paul swed]

OK the AN/URQ-13 is all buttoned up and powered up and working well. A
dangerous statement to be made on Time-nuts. That said 5 XE-11 from what I
see.
That said consumes about 5 watts.
But since the units been off for at least 15 years and heavens knows how
long before that. Any thoughts on how long it might take to stabilize days
weeks months. Its pretty stable as is just wondering.
Regards
Paul
WB8TSL
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Re: [time-nuts] World's most precise.... wall clock

[Ben Bradley]

This might be desirable.

https://www.ebay.com/itm/THE-AMATEUR-SCIENTIST-ON-CD-ROM-LATEST-EDITION-VERSION-4-M2071-/112117678275

On Wed, Mar 3, 2021 at 4:19 PM Chris Caudle <6807.ch...@pop.powweb.com> wrote:
>
> > On Tue, 02 Mar 2021 22:42:45 -0800
> > Hal Murray  wrote:
> >
> >> The basic idea is to mount a magnet on a stiff wire so that it sticks
> >> out to
> >> the side of the pendulum arm, then mount a coil so the magnet will
> >> swing
> >> through it.  Now pulse the coil to get the desired results.
>
> On 2021-03-03 02:54, Attila Kinali wrote:
> > This is basically injection locking of a pendulum clock.
> > Pendulum clocks are very nice for injection locking, due
> > to their relatively low Q and because a magnetic field can
> > be easily adjusted in strength.
>
>
> I don't have the reference at hand right away, but I did see an article
> in the past describing a mechanism which placed the magnet on the end of
> the pendulum, and had one coil to sense the magnet swinging past, and
> another coil to provide the impulse to the pendulum.  The timing of the
> impulse was controlled by a microcontroller, so it could provide some
> rough phase locking function by varying the time between the detection
> pulse and the driven impulse, and maybe the amplitude or length of the
> impulse.
> If there is interest I can see if I can find that article again, but
> that may be straying from the original request, which seemed to be
> looking for something with a digital display.
>
> --
> Chris Caudle
>
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Re: [time-nuts] World's most precise.... wall clock

[Chris Caudle]

On Tue, 02 Mar 2021 22:42:45 -0800
Hal Murray  wrote:

The basic idea is to mount a magnet on a stiff wire so that it sticks 
out to
the side of the pendulum arm, then mount a coil so the magnet will 
swing

through it.  Now pulse the coil to get the desired results.


On 2021-03-03 02:54, Attila Kinali wrote:

This is basically injection locking of a pendulum clock.
Pendulum clocks are very nice for injection locking, due
to their relatively low Q and because a magnetic field can
be easily adjusted in strength.



I don't have the reference at hand right away, but I did see an article 
in the past describing a mechanism which placed the magnet on the end of 
the pendulum, and had one coil to sense the magnet swinging past, and 
another coil to provide the impulse to the pendulum.  The timing of the 
impulse was controlled by a microcontroller, so it could provide some 
rough phase locking function by varying the time between the detection 
pulse and the driven impulse, and maybe the amplitude or length of the 
impulse.
If there is interest I can see if I can find that article again, but 
that may be straying from the original request, which seemed to be 
looking for something with a digital display.


--
Chris Caudle

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Re: [time-nuts] World's most precise.... wall clock

[John Sloan]

I’ve built several small home-brew NTP servers using a Raspberry Pi,
a GPS receiver, and an LCD display. Most of them are desk clocks.
My favorite one (and the biggest money sink) is a mantle clock in my
living room that incorporates a chip-scale cesium “atomic clock”.

Photo: https://flic.kr/p/2kqoHC7

Blog article: 
https://coverclock.blogspot.com/2017/05/my-stratum-0-atomic-clock_9.html

Git repo: https://github.com/coverclock/com-diag-astrolabe

--
J. L. SloanDigital Aggregates Corp.
+1 303 940 9064 (O)3440 Youngfield St. #209
+1 303 489 5178 (M)Wheat Ridge CO 80033 USA
jsl...@diag.comhttp://www.diag.com 


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Re: [time-nuts] Old Crystal.

[Dan Kemppainen]

Hi All,

Many thanks to all who replied. I've beep picking my way through the 
suggestion, videos, and other information.


The next steps will be to try to measure some of the crystal parameters 
with the stuff I have laying around the lab. The supplied information 
will keep me working on this for a while.


I did find one ebay seller who managed to make these tubes glow blue! 
Not sure how much voltage or what frequency it was getting hit with, but 
it appears to be arcing in/on/through the crystal. Hopefully the ones I 
have weren't mistreated this way!


Thanks,
Dan

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Re: [time-nuts] World's most precise.... wall clock

[Edesio Costa e Silva]

Hi!

I found a copy at 


Edésio

On Tue, Mar 02, 2021 at 10:42:45PM -0800, Hal Murray wrote:
> > Maybe one day I'll make this work with a grandfather clock.
>
> Many years ago, Scientific American had an article describing adding a magnet
> to the pendulum and the circuitry to drive it.
>
> The basic idea is to mount a magnet on a stiff wire so that it sticks out to
> the side of the pendulum arm, then mount a coil so the magnet will swing
> through it.  Now pulse the coil to get the desired results.
>
> Scientific American, September 1974, Amateur Scientist
> A venerable clock is made highly accurate by equipping it with quartz-crystal 
> works
>
> They want $8 for a pdf.
> https://www.scientificamerican.com/article/the-amateur-scientist-1974-09/
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
>
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Re: [time-nuts] World's most precise.... wall clock

[Attila Kinali]

On Tue, 02 Mar 2021 22:42:45 -0800
Hal Murray  wrote:

> The basic idea is to mount a magnet on a stiff wire so that it sticks out to 
> the side of the pendulum arm, then mount a coil so the magnet will swing 
> through it.  Now pulse the coil to get the desired results.

This is basically injection locking of a pendulum clock.
Pendulum clocks are very nice for injection locking, due
to their relatively low Q and because a magnetic field can
be easily adjusted in strength.

You don't need to place the magnet at any one specific position.
It is enough that it is somewhere in the path of the pendulum.
My favorite position is right beneath the center.

The injected pulses should be long enough to have an effect
with a reasonably weak magnetic field, but short enough to
be an impulse, from the point of view of the mechanical system.
I.e. the pulse length should be a fraction of the time it take
for the pendulum to pass the magnet. Somewhere between 1/2
and 1/10 should work in most cases.

Start with getting the pendulum clock as close to the right
rate as possible. Place the magnet where it suits you best.
Then adjust the current through the magnet such that you can
barely feel some resistance when you move the pendulum through
the field with your hands. Set your electronics to inject pulses
at the appropriate rate. This does not have to be at every pass,
but can be, e.g., every 10th pass. Now let the clock run and see
whether you get proper synchronization/locking. If not, increase
the current through the magnet step wise until it is strong enough
for synchronization. Test over varying temperatures, air humidity
and pressure to ensure that changes of the natural frequency of
the pendulum don't get your clock unlocked.

If you have trouble with keeping the clock locked and don't want
to increase the current any further, increase the pulse length.

For additionaly time-nuttyness, you can add a sensor somewhere in
the path of the pendulum and measure its phase versus true
time. Suitable sensors are fork light barriers and Hal sensors.


Attila Kinal
-- 
The driving force behind research is the question: "Why?"
There are things we don't understand and things we always 
wonder about. And that's why we do research.
-- Kobayashi Makoto

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Re: [time-nuts] World's most precise.... wall clock

[David Taylor via time-nuts]

On 02/03/2021 22:38, Eamonn Nugent wrote:

Hi!

I have a perhaps silly question. I want to take an inferior medium (our
eyes) and give it something attractively precise to look at. Is there such
a thing as a digital (wall) clock with a 1PPS/10MHz/etc. input? I see that
some clocks have GPS antenna inputs, but I want to take a GPSDO and hook it
up to a digital clock. Purely for fun, as a mini project for myself while I
build my bigger clocks.

Maybe one day I'll make this work with a grandfather clock.

Thanks,

Eamonn

Eamonn,

I built my own with a Raspberry Pi.  As it's display-based you can make 
it look just as you wish.


  https://www.satsignal.eu/raspberry-pi/DigitalClock.html

Mine takes 1pps/NMEA deom a GPS.

David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv

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