[time-nuts] Grandfather clock sync'd to 1PPS (from time-nuts Digest, Vol 200, Issue 4)
Philip Gladstone
pjsg-timenuts at nospam.gladstonefamily.net
Wed Mar 10 16:58:26 UTC 2021
I solved the rewind problem by putting an alarm on my phone for noon on
Sundays. During the pandemic, I'm always home, so that works out too!
On Wed, Mar 10, 2021 at 11:52 AM Dana Whitlow <k8yumdoober at gmail.com> wrote:
> Philip,
>
> You and I are definitely "in sync" regarding cheating to alter the pendulum
> motions!
>
> I had a very similar thought for effectively making the pendulum based
> system into sort
> of a VCO, except that instead of a metal plate, use a small Nd magnet
> polarized
> vertically, stealthily-attached to the back of the pendulum bob near the
> bottom. Then a
> current applied through the control coil could either increase of decrease
> the effective pull
> of gravity at will, and in a well-tuned system would average near zero
> current. Thus if the
> power to the system failed, the clock would continue to run very close to
> the correct
> rate for good holdover.
>
> My big problem is that I'd never remember to "rewind" the clock's primary
> energy storage
> mechanism.
>
> Dana
>
>
> On Wed, Mar 10, 2021 at 10:10 AM Philip Gladstone <
> pjsg-timenuts at nospam.gladstonefamily.net> wrote:
>
> > I've been wanting to do this as well, but I feel that it is "cheating" to
> > actively drive the pendulum. I want to have a passive approach to
> > disciplining the clock so that the clock itself is keeping time.
> >
> > One approach that I have seen was to put a magnet at the bottom of the
> > pendulum and then have a metal plate beneath it -- and the correction is
> > performed by adjusting the vertical position of the plate. This
> effectively
> > changes the local gravity and hence the tick period. However, I don't
> think
> > that this will look "nice". I'm hoping that I can do the same magnet
> trick,
> > but put it much higher on the pendulum so that it is hidden when you open
> > the clock case door. I envisage having the metal plate position being
> > controlled by a small stepper motor. I'd like to have a range of maybe
> > +/-50ppm with a resolution of around 1ppm. This seems doable....
> >
> > Thoughts?
> >
> > Philip
> >
> > On Sat, Mar 6, 2021 at 2:12 PM Gerald Swann <gds32571 at gmail.com> wrote:
> >
> > > Eamonn and all,
> > >
> > > You mentioned you hope to get your grandfather clock time
> synchronized
> > > to a 1PPS signal. That would be a very satisfying project, I can
> assure
> > > you. I did that with my own grandfather clock. My father built the
> > clock
> > > quite a number of years ago from a kit, and used walnut wood from a
> tree
> > > that was harvested from somewhere in Indiana to build the actual clock
> > > body.
> > >
> > > On github at https://github.com/gds32571/gdsPendulum you can see
> the
> > > operating code for the Arduino-based controller that performs this
> feat.
> > > There are lots of comments within the code, but I don't want to leave
> > that
> > > as the only info to help you understand, so some explanation follows.
> > > Within the README.md file are links to pictures and to a graph showing
> > data
> > > regarding the pendulum swing.
> > >
> > > There were several interesting descriptions of how one might use a
> > > magnet to influence the swing of the pendulum. I took an approach not
> > > mentioned in the digest email. For a simple pendulum, only two factors
> > > affect the period: the length of the pendulum and the gravity field the
> > > pendulum is swinging in.
> > >
> > > I fastened a steel screw held in an alligator clip to the bottom of
> > the
> > > pendulum, and then adjusted the pendulum weight so that the pendulum
> > would
> > > swing a little slower than necessary to keep time. I took the coil
> from
> > a
> > > 24v relay and mounted it on a cardboard rack sitting in the bottom of
> the
> > > clock cabinet such that the steel screw swings just above the core of
> the
> > > relay coil. This relay coil, when energized, has the effect of
> slightly
> > > increasing the attraction of the pendulum towards the center of earth -
> > > more gravity you might say.
> > >
> > > The same cardboard rack holds a blue LED and a phototransistor
> > > (TEPT5600) such that the light from the LED shines on the
> > phototransistor.
> > > The weight attached to the end of the pendulum, blocks the light every
> > > swing. This generates a signal I use to measure the phase of the
> > pendulum
> > > relative to the 1PPS signal.
> > >
> > > When I started thinking about this, I thought I could use some fancy
> > > timing to generate pulses that could speed up or slow down the
> pendulum,
> > as
> > > I desired. That was not to be, at least within my ability, the
> pendulum
> > > can only be sped up. So I just measure the phase of the pendulum
> > relative
> > > to the 1PPS and energize the coil if the pendulum is lagging behind.
> The
> > > arduino controller energizes the coil for a number of seconds each
> > minute.
> > > In the graph, you can see that the magnetism time is 19 beats for this
> > > minute.
> > >
> > > I didn't notice before I started this project, the pendulum period
> is
> > > not 2 seconds as I would have expected. It actually swings 33 times in
> > one
> > > minute, giving a period of 1.81818 seconds. This means that the phase
> > > measurement of the swing will line up with only one pulse from the GPS
> > > every ten seconds.
> > >
> > > The arduino outputs a text message once a minute with some control
> > info
> > > including the phase, the time spent energizing the magnet, etc. This
> > > serial output from the arduino feeds a Raspberry Pi that generates the
> > > stats graph.
> > >
> > > The green plot line is the measured phase difference. You might
> think
> > > the clock was off by 800 milliseconds, but actually it is sync'd to the
> > > 1PPS pulse that occurs just before the top of the minute. So, right
> now,
> > > the clock time rolls over about 182 milliseconds before the top of the
> > > minute. That's also why the GPS time shows as one second before the
> GFC
> > > time. You can also see the clock phase has slipped somewhat when I
> wound
> > > the clock yesterday morning (27 hours ago). If I play with the setting
> > of
> > > the clock, I can get the phase difference to within a few milliseconds.
> > > And it will stay there for weeks.
> > >
> > > The Arduino controller has been running for 37 days this time, since
> > it
> > > was last reset. It is not super accurate compared to many GPS clocks,
> > but
> > > it will be as correct as anyone can read the minute and hour hands.
> > But,
> > > if I forget to wind the clock, the driving weight will hit the
> cardboard
> > > rack and stop the clock. So I get a chance to set it again.
> > >
> > > One more thing, the "Big Ben" style chiming mechanism built into the
> > > grandfather clock has some broken pins, so it skips some of the notes
> in
> > > the quarter hour and top of the hour chiming. To avoid this, I added a
> > > midi synthesizer to the controller. The clock now chimes
> electronically.
> > > There is also a PIR sensor to sense motion so that the clock can lower
> > the
> > > chime volume if someone is in the same room as the clock.
> > >
> > > The grandfather clock face time is unaffected by any of the
> circuits I
> > > added, so it continues to display the time as you would expect. There
> is
> > > also a seven segment display connected to the Arduino controller that
> > > displays the time digitally, counting pendulum swings.
> > >
> > > I also have two more Arduino clocks on the same table. One displays
> > the
> > > time extracted from the NMEA sentences sent from a second GPS. The
> other
> > > Arduino clock counts the 1PPS pulses from the first GPS and displays
> the
> > > accumulated time on its own display. I originally used a Motorola
> Oncore
> > > GPS UT+ I think it was, which was rock solid, never missing a pulse.
> > Now,
> > > I am using an Adafruit GPS mounted in the middle of the room, not near
> a
> > > window. It will occasionally drop pulses which confuses the clock
> > > controller. So the Arduino program running this clock generates the
> > missing
> > > 1PPS pulses to keep the GFC controller happy. Seems to work.
> > >
> > > The circuitry is very simple, but I do not have a schematic. It's
> > just
> > > a couple of transistors and the Arduino. I hope to do a better job of
> > > documenting this project in the coming months I hope you found
> > > this interesting and I haven't taken up too much of your time.
> > >
> > > Thanks,
> > >
> > > Gerald
> > > AI4DE
> > >
> > > On Wed, Mar 3, 2021 at 12:00 PM <time-nuts-request at lists.febo.com>
> > wrote:
> > >
> > > > Send time-nuts mailing list submissions to
> > > > time-nuts at lists.febo.com
> > > >
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> > > >
> > > > When replying, please edit your Subject line so it is more specific
> > > > than "Re: Contents of time-nuts digest..."
> > > >
> > > >
> > > > Today's Topics:
> > > >
> > > > 1. Re: Old Crystal. (Bob kb8tq)
> > > > 2. World's most precise.... wall clock (Eamonn Nugent)
> > > > 3. Re: World's most precise.... wall clock (Bill Beam)
> > > > 4. Re: World's most precise.... wall clock (ed breya)
> > > > 5. NPL courses on time and frequency measurement (Dr. David
> Kirkby)
> > > > 6. Re: World's most precise.... wall clock (Lux, Jim)
> > > > 7. Re: World's most precise.... wall clock (Tom Van Baak)
> > > > 8. Re: World's most precise.... wall clock (DM)
> > > > 9. Re: World's most precise.... wall clock (Hal Murray)
> > > > 10. Re: World's most precise.... wall clock (David Taylor)
> > > > 11. Re: World's most precise.... wall clock (Attila Kinali)
> > > > 12. Re: World's most precise.... wall clock (Edesio Costa e Silva)
> > > >
> > > >
> > > >
> ----------------------------------------------------------------------
> > > >
> > > > Message: 1
> > > > Date: Tue, 2 Mar 2021 12:37:09 -0500
> > > > From: Bob kb8tq <kb8tq at n1k.org>
> > > > To: Discussion of precise time and frequency measurement
> > > > <time-nuts at lists.febo.com>
> > > > Subject: Re: [time-nuts] Old Crystal.
> > > > Message-ID: <E982F541-5591-4E81-B7E0-5C875539047F at n1k.org>
> > > > Content-Type: text/plain; charset=utf-8
> > > >
> > > > 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 <eb4apl at gmail.com> 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 escribi?:
> > > > >> 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
> > > > >
> > > > > --
> > > > > El software de antivirus Avast ha analizado este correo electr?nico
> > en
> > > > busca de virus.
> > > > > https://www.avast.com/antivirus
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > > time-nuts mailing list -- time-nuts at lists.febo.com
> > > > > To unsubscribe, go to
> > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > > > > and follow the instructions there.
> > > >
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 2
> > > > Date: Tue, 2 Mar 2021 17:38:24 -0500
> > > > From: Eamonn Nugent <elg.nugent at gmail.com>
> > > > To: time-nuts at lists.febo.com
> > > > Subject: [time-nuts] World's most precise.... wall clock
> > > > Message-ID:
> > > > <CAPQA=
> > > > kH+B87DQQVTkWnrh+9y_d2udRh58-KpkdYha7zZamdnZg at mail.gmail.com>
> > > > Content-Type: text/plain; charset="UTF-8"
> > > >
> > > > 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
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 3
> > > > Date: Tue, 02 Mar 2021 15:16:58 -0900
> > > > From: "Bill Beam" <wbeam at gci.net>
> > > > To: "Eamonn Nugent" <elg.nugent at gmail.com>, "
> time-nuts at lists.febo.com"
> > > > <time-nuts at lists.febo.com>
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID: <E9.43.19889.E75DE306 at smtp01.beryl.bos.sync.lan>
> > > > Content-Type: text/plain; charset="us-ascii"
> > > >
> > > > Hi,
> > > >
> > > > I had same question several years ago.
> > > >
> > > > You're gonna have to roll your own.
> > > >
> > > > Look here <
> > https://hassam794.weebly.com/digital-clock-using-4026-ic.html
> > > >
> > > >
> > > >
> > > >
> > > > 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
> > > > >_______________________________________________
> > > > >time-nuts mailing list -- time-nuts at lists.febo.com
> > > > >To unsubscribe, go to
> > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > > > >and follow the instructions there.
> > > >
> > > >
> > > > Bill Beam
> > > > NL7F
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 4
> > > > Date: Tue, 2 Mar 2021 16:32:47 -0800
> > > > From: ed breya <eb at telight.com>
> > > > To: time-nuts at lists.febo.com
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID: <603ED92F.1030009 at telight.com>
> > > > Content-Type: text/plain; charset=utf-8; format=flowed
> > > >
> > > > 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
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 5
> > > > Date: Wed, 3 Mar 2021 00:45:43 +0000
> > > > From: "Dr. David Kirkby" <drkirkby at kirkbymicrowave.co.uk>
> > > > To: "time-nuts at lists.febo.com" <time-nuts at lists.febo.com>
> > > > Subject: [time-nuts] NPL courses on time and frequency measurement
> > > > Message-ID:
> > > > <
> > > > CANX10hDyPo4mG2-LVCo7_NBzgQ4A4GAt9uWkkKjUdYVvGf71qg at mail.gmail.com>
> > > > Content-Type: text/plain; charset="UTF-8"
> > > >
> > > > 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.
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 6
> > > > Date: Tue, 2 Mar 2021 17:17:38 -0800
> > > > From: "Lux, Jim" <jim at luxfamily.com>
> > > > To: time-nuts at lists.febo.com
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID: <586e610a-b13f-4872-a26e-9930fd0df3aa at luxfamily.com>
> > > > Content-Type: text/plain; charset=utf-8; format=flowed
> > > >
> > > > 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
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 7
> > > > Date: Tue, 2 Mar 2021 17:27:15 -0800
> > > > From: Tom Van Baak <tvb at LeapSecond.com>
> > > > To: time-nuts at lists.febo.com
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID: <a88d22d6-4400-8725-fa7d-3961c41fcd60 at LeapSecond.com>
> > > > Content-Type: text/plain; charset=utf-8; format=flowed
> > > >
> > > > 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
> > > > > _______________________________________________
> > > > > time-nuts mailing list -- time-nuts at lists.febo.com
> > > > > To unsubscribe, go to
> > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > > > > and follow the instructions there.
> > > > >
> > > >
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 8
> > > > Date: Tue, 2 Mar 2021 21:41:47 -0500 (EST)
> > > > From: DM <dgminala at mediacombb.net>
> > > > To: Discussion of precise time and frequency measurement
> > > > <time-nuts at lists.febo.com>
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID:
> > > > <
> > 684600294.21613154.1614739307850.JavaMail.zimbra at mediacombb.net
> > > >
> > > > Content-Type: text/plain; charset=utf-8
> > > >
> > > > 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" <elg.nugent at gmail.com>
> > > > To: time-nuts at 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
> > > > _______________________________________________
> > > > time-nuts mailing list -- time-nuts at lists.febo.com
> > > > To unsubscribe, go to
> > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > > > and follow the instructions there.
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 9
> > > > Date: Tue, 02 Mar 2021 22:42:45 -0800
> > > > From: Hal Murray <hmurray at megapathdsl.net>
> > > > To: Discussion of precise time and frequency measurement
> > > > <time-nuts at lists.febo.com>
> > > > Cc: hmurray at megapathdsl.net
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID:
> > > > <20210303064245.9FA6140605C at ip-64-139-1-69.sjc.megapath.net>
> > > > Content-Type: text/plain; charset=us-ascii
> > > >
> > > > > 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.
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 10
> > > > Date: Wed, 3 Mar 2021 08:37:53 +0000
> > > > From: David Taylor <david-taylor at blueyonder.co.uk>
> > > > To: time-nuts at lists.febo.com
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID: <1393578e-89cf-c8f1-434a-9c649e46dae5 at blueyonder.co.uk>
> > > > Content-Type: text/plain; charset=utf-8; format=flowed
> > > >
> > > > 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-taylor at blueyonder.co.uk
> > > > Twitter: @gm8arv
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 11
> > > > Date: Wed, 3 Mar 2021 09:54:36 +0100
> > > > From: Attila Kinali <attila at kinali.ch>
> > > > To: Discussion of precise time and frequency measurement
> > > > <time-nuts at lists.febo.com>
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID: <20210303095436.40523a874e437af353260c23 at kinali.ch>
> > > > Content-Type: text/plain; charset=US-ASCII
> > > >
> > > > On Tue, 02 Mar 2021 22:42:45 -0800
> > > > Hal Murray <hmurray at megapathdsl.net> 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
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Message: 12
> > > > Date: Wed, 3 Mar 2021 12:00:31 -0300
> > > > From: Edesio Costa e Silva <edesio at softaplic.com.br>
> > > > To: Discussion of precise time and frequency measurement
> > > > <time-nuts at lists.febo.com>
> > > > Cc: Hal Murray <hmurray at megapathdsl.net>
> > > > Subject: Re: [time-nuts] World's most precise.... wall clock
> > > > Message-ID: <20210303150030.GA3590 at softaplic.com.br>
> > > > Content-Type: text/plain; charset=iso-8859-1
> > > >
> > > > Hi!
> > > >
> > > > I found a copy at <
> > > > https://www.g8wrb.co.uk/useful-stuff/time/pdf/pendulum+quartz.pdf>
> > > >
> > > > Ed?sio
> > > >
> > > > 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.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > _______________________________________________
> > > > > time-nuts mailing list -- time-nuts at lists.febo.com
> > > > > To unsubscribe, go to
> > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > > > > and follow the instructions there.
> > > >
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > Subject: Digest Footer
> > > >
> > > > _______________________________________________
> > > > time-nuts mailing list
> > > > time-nuts at lists.febo.com
> > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > > >
> > > >
> > > > ------------------------------
> > > >
> > > > End of time-nuts Digest, Vol 200, Issue 4
> > > > *****************************************
> > > >
> > > _______________________________________________
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> > > and follow the instructions there.
> > >
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> > To unsubscribe, go to
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> > and follow the instructions there.
> >
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