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

[Hal Murray]

> 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

[DM]

Here are a few online projects for GPS-controlled clocks. Most (all?) have a 
PIC or Arduino to run the clock and sync to GPS time. 
[ http://w8bh.net/avr/clock2.pdf | http://w8bh.net/avr/clock2.pdf ] 
https://www.elprocus.com/how-to-build-a-gps-clock-using-arduino/ 
https://learn.adafruit.com/arduino-clock 
https://www.tindie.com/products/nsayer/gps-clock/ 
https://mitxela.com/shop/clock 
https://www.sparkfun.com/tutorials/47 

DIY projects are easy to find with Google: 
The search string I used was: gps digital clock kit OR diy OR build 

There are a number of clocks with Nixie tube displays also; just add "nixie" to 
the Google search string. 

Good luck 
Dave M 




From: "Eamonn Nugent"  
To: time-nuts@lists.febo.com 
Sent: Tuesday, March 2, 2021 4:38:24 PM 
Subject: [time-nuts] World's most precise wall clock 

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

[Tom Van Baak]

Eamonn,

Here are a couple of ideas for you:

1) You may find some GPS / NTP / 1PPS / 10 MHz precise time friendly 
professional clocks at:


https://www.masterclock.com/

2) If you have a 50/60 Hz mains wall clock you can always use this trick:

http://leapsecond.com/pages/atomic-nixie/

3) You can convert your perfect 10 MHz into perfect 32.768 Hz and inject 
that into any cheap 32 kHz tuning fork clock. Sometimes it's as simple 
as one wire. Watch one for one problem: some newer 32 kHz clocks use 
cycle slipping in which case feeding in exactly 32768 Hz will result in 
a very slight loss of time as far as the hands show.


A $1 solution to converting 10 MHz to 32 kHz is:

http://leapsecond.com/pic/src/pd30.asm
http://leapsecond.com/pic/picdiv.htm

4) You can convert your perfect GPS/1PPS into the bipolar stepper 
signals used by the Lavet motor in almost all analog wrist / desk / wall 
clocks:


https://en.wikipedia.org/wiki/Lavet-type_stepping_motor
http://leapsecond.com/pages/32kHz/

5) If you want sidereal time, another $1 PIC solution, see PD28 and PD29 at:

http://leapsecond.com/pic/src/

This technique can be adapted to a wide range of frequencies.

6) Projects to hack / adapt display clocks to Rb or Cs or GPS/GPSDO 
timing sources is not uncommon on sites like Hackaday.com so have a look 
there as well.


/tvb

On 3/2/2021 2:38 PM, 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
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Re: [time-nuts] World's most precise.... wall clock

[Lux, Jim]

On 3/2/21 4:32 PM, ed breya wrote:
If you can open it up and get at and identify the crystal, you can 
synthesize its ideal frequency from a GPSDO output, then run it in 
there in place of the crystal. 




I did this for a 24hr Mars clock using a 3325 to generate 31947.2745 Hz



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[time-nuts] NPL courses on time and frequency measurement

[Dr. David Kirkby]

It looks like NPL are in the process of creating some courses on this.
Introduction to Time and Frequency Measurement
https://elearning.npl.co.uk/enrol/index.php?id=53

I think I read something on the NPL site to imply that was free, but I
can't see that now. Anyway, it's not available yet, but it is obvious they
intend producing some courses.
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Re: [time-nuts] World's most precise.... wall clock

[ed breya]

If you can open it up and get at and identify the crystal, you can 
synthesize its ideal frequency from a GPSDO output, then run it in there 
in place of the crystal.


Ed

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

[Bill Beam]

Hi,

I had same question several years ago.

You're gonna have to roll your own.

Look here 



On Tue, 2 Mar 2021 17:38:24 -0500, 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
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>http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>and follow the instructions there.


Bill Beam
NL7F




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

[Eamonn Nugent]

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
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Re: [time-nuts] Old Crystal.

[Bob kb8tq]

Hi

You don’t necessarily  need to convert to a 12.5 ohm system. A lot depends on 
just what your objectives are. 

It a bit like needing a fancy Fluke Hart Chub thermometer if you are only after
a couple of degree accuracy. The tools vary depending on the job.

Bob

> On Mar 1, 2021, at 3:23 PM, EB4APL  wrote:
> 
> My response got lost in the Internet, so I repeat the info.
> 
> If you have access to a Network Analyzer, either Scalar or Vector,  you can 
> measure the crystal parameters. You need a test fixture (it could be 
> homemade) to convert the 50 Ohm analyzer impedance to 12.5 Ohm and you very 
> slowly sweep the crystal to obtain its serial resonance (frequency and 
> attenuation) the and the -3dB points frequencies. From these measurements 
> there are simple formulas to obtain the motional resistance, inductance and 
> capacitance, and the crystal Q.
> 
> Some professional Network Analyzers seems not to be very adequate to do this 
> because they cannot sweep slowly enough, but some low cost hobby type 
> analyzers have a mode for measuring crystals with these calculations 
> integrated. One example being the Poor Ham Scalar Network Analyzer which has 
> a function for specifically measuring crystals using a step rate of 1 Hz and 
> the nanoVNA, that can measure the resonance point and you do the 
> calculations. A program with the measurements and calculations integrated is 
> under development at this time.
> 
> This an example of the PHSNA output:
> 
> Crystal Id:  8 Mhz #3
> Peak Frec. (Hz):  7996356
> Bandwidth (Hz):  354,5
> Rs (Ohm):  24,3
> Lm (mH): 22,13353409
> Cm (pF): 0,01789803
> Q:   45763
> 
> Regards,
> 
> Ignacio EB4APL
> 
> 
> El 01/03/2021 a las 0:35, Dan Kemppainen escribió:
>> Hi All,
>> 
>> I've picked up a couple of old crystals. Mostly because they look neat. They 
>> are 1Mhz, in a glass tube. The quartz is ~25mm dia, at about 1 mm thick. Was 
>> able to get them to oscillate using a Colpitts circuit. They will oscillate 
>> at 2.851Mhz (probably some strange mode)  if given the chance.
>> 
>> I've been scouring my reference books here, and haven't had much luck 
>> finding any details on how one would even guess at the parameters of a 
>> quartz like this.
>> 
>> There area few numbers on them, 33 stamped on the side, 1000 (KHz???) on the 
>> top, 87 on the top, and hand written 501 (probably a SN). Digging on line, 
>> I'd guess an AT cut based on thickness. I'm guessing the 33 is capacitance 
>> in pF. 87, might be year.
>> 
>> If any of you have any suggestions on where to find information on how to 
>> get something like this to oscillate properly, guess at correct parameters, 
>> or even measure any of the parameters I would really appreciate it.
>> 
>> I'm sure these are really nothing special, but it would be neat to give them 
>> a fighting chance to show what they can or can't do without breaking them!
>> 
>> Thanks,
>> Dan 
> 
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