N/A Grandfather Clock

Terry

Terry

Line Up and Wait
Joined
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Terry
I have a Grandfather clock that keeps excellent time. Every fall, I have to set the pendulum weight out 1/4 of a turn because the clock speeds up. Then it will keep excellent time until spring when I will shorten the pendulum swing by 1/4 turn.
It then keeps time until the next fall season.

I live in Central Kansas.

Any scientific theory or ideas?

Terry
 
It's normal. Changes in temperature and humidity will make the pendulum rod shrink and grow seasonally. Mine's the same way.
 
Your clock is protesting daylight savings.
 
It's global warming :)
 
Terry said:
I have a Grandfather clock that keeps excellent time. Every fall, I have to set the pendulum weight out 1/4 of a turn because the clock speeds up. Then it will keep excellent time until spring when I will shorten the pendulum swing by 1/4 turn.
It then keeps time until the next fall season.

I live in Central Kansas.

Any scientific theory or ideas?

Terry
Click to expand...

Against what time source are you comparing your clock? I use WWV HF broadcast transmissions or GPS clock.

José
 
Terry said:
I have a Grandfather clock that keeps excellent time. Every fall, I have to set the pendulum weight out 1/4 of a turn because the clock speeds up. Then it will keep excellent time until spring when I will shorten the pendulum swing by 1/4 turn.
It then keeps time until the next fall season.

I live in Central Kansas.

Any scientific theory or ideas?

Terry
Click to expand...

Have you ever had an encounter with some guy who calls himself "The Doctor" and lives in a British police call box that he calls a TARDIS??

:D
 
Just buy an iPhone or some sort of personal computer. The time will be automatically synced with the NIST server whether you like it or not.
 
Sac Arrow said:
Just buy an iPhone or some sort of personal computer. The time will be automatically synced with the NIST server whether you like it or not.
Click to expand...

Needed for A-GPS on the phones for E911 requirements. Especially well-synced on CDMA based networks.

PC synching in most OSs is off by at least the propagation delay to the server used.

Got a couple of friends who are into the whole "wildly accurate clocks" hobby. Started with a desire to have a dead-nuts on 10 MHz clock source for microwave radio tinkering on the bench and then they get sucked in.

Both are playing with surplus rubidium standards that are GPS disciplined. They can tell ya out to a surprising number of decimal places just how far off the consumer stuff is. It's a hobby I guess.

Synching the RF test gear to a solid 10 MHz source is nice on the workbench. WWV is fine really for most folks. But it's nice to lock the transverters to a source for microwave ops. Less tuning around chasing the other guy. My 10 GHz transverter drifted significantly for the ten minutes or so while the crystal oven warmed up.
 
While we're on the subject of time here's a random tidbit. You can call the alternate DoD master clock in Colorado Springs at 719-567-6742. It's the clock that the GPS constellation uses.
 
e.pie said:
While we're on the subject of time here's a random tidbit. You can call the alternate DoD master clock in Colorado Springs at 719-567-6742. It's the clock that the GPS constellation uses.
Click to expand...


That clock has been turned off due to the guvmint shut down.... Who says time can't stand still..:dunno:;):D
 
denverpilot said:
Needed for A-GPS on the phones for E911 requirements. Especially well-synced on CDMA based networks.

PC synching in most OSs is off by at least the propagation delay to the server used.

Got a couple of friends who are into the whole "wildly accurate clocks" hobby. Started with a desire to have a dead-nuts on 10 MHz clock source for microwave radio tinkering on the bench and then they get sucked in.

Both are playing with surplus rubidium standards that are GPS disciplined. They can tell ya out to a surprising number of decimal places just how far off the consumer stuff is. It's a hobby I guess.

Synching the RF test gear to a solid 10 MHz source is nice on the workbench. WWV is fine really for most folks. But it's nice to lock the transverters to a source for microwave ops. Less tuning around chasing the other guy. My 10 GHz transverter drifted significantly for the ten minutes or so while the crystal oven warmed up.
Click to expand...

And there's some stuff I know about that makes the rubidium clocks look like consumer stuff in terms of accuracy. Enables even faster financial processing (and not just bitcoins....) & other fun stuff.
 
Terry said:
I have a Grandfather clock that keeps excellent time. Every fall, I have to set the pendulum weight out 1/4 of a turn because the clock speeds up. Then it will keep excellent time until spring when I will shorten the pendulum swing by 1/4 turn.
It then keeps time until the next fall season.

I live in Central Kansas.

Any scientific theory or ideas?

Terry
Click to expand...

Like others said - it's probably the change in seasons (temperature/humidity) having an affect.

Maybe you need to take it flying:

http://en.wikipedia.org/wiki/Hafele–Keating_experiment
 
Nate, I recently finished up the design for a new repeater controller. Just for guys like you, I designed it so you can attach a GPS receiver and it will sync its internal RTC every half hour, if the GPS is talking. That way you can have "beacon" IDs synched to the real time.

No provision for a rubidium time standard, though.
 
Terry said:
Any scientific theory or ideas?
Click to expand...

I had a theory based on the gravity of the Sun slightly canceling the Earth's gravity more in the winter than in the summer because the Earth is closer to the Sun in the winter. But your data contradicts my theory, so there must be other factors that have a bigger effect.

If it keeps excellent time, why don't you just adjust it 1/8" and then leave it alone?
 
denverpilot said:
Needed for A-GPS on the phones for E911 requirements. Especially well-synced on CDMA based networks.

PC synching in most OSs is off by at least the propagation delay to the server used.

Got a couple of friends who are into the whole "wildly accurate clocks" hobby. Started with a desire to have a dead-nuts on 10 MHz clock source for microwave radio tinkering on the bench and then they get sucked in.

Both are playing with surplus rubidium standards that are GPS disciplined. They can tell ya out to a surprising number of decimal places just how far off the consumer stuff is. It's a hobby I guess.

Synching the RF test gear to a solid 10 MHz source is nice on the workbench. WWV is fine really for most folks. But it's nice to lock the transverters to a source for microwave ops. Less tuning around chasing the other guy. My 10 GHz transverter drifted significantly for the ten minutes or so while the crystal oven warmed up.
Click to expand...

Years ago I retrieved a precision 10mhz source from the recycling bin. It was a marvel of old-school engineering. Two thermostatically controlled ovens, one inside the other and the crystal inside the inside one. Harmonic freqency doublers from the crystal frequency of 1 mhz. Test meter on the operator's panel with a selector switch to check a dozen parameters. Just for fun I hooked it up to my vintage HP frequency counter equipped with the "precision clock oscillator" options. The two old boys agreed within 30 billionths of a second.

Then I gave the recycling bin source to one of those "wildly accurate clock" guys.
 
Terry said:
I live in Central Kansas.
Click to expand...

LaCrosse can't be too big a place, my daughter's first roomate at ESU is from there.

All in all, if you are just making slight adjustments twice a year because the temp/humidity level in some parts are changing, I think you are doing very well indeed.
 
Temperature and humidity make a lot of sense.

Thanks everyone,
Terry
 
denverpilot said:
PC synching in most OSs is off by at least the propagation delay to the server used.
Click to expand...

The NTP protocol is designed to handle any propogation delay:
http://www.eecis.udel.edu/~mills/ntp/html/warp.html


denverpilot said:
Got a couple of friends who are into the whole "wildly accurate clocks" hobby. Started with a desire to have a dead-nuts on 10 MHz clock source for microwave radio tinkering on the bench and then they get sucked in.

Both are playing with surplus rubidium standards that are GPS disciplined. They can tell ya out to a surprising number of decimal places just how far off the consumer stuff is. It's a hobby I guess.
....
Click to expand...

wsuffa said:
And there's some stuff I know about that makes the rubidium clocks look like consumer stuff in terms of accuracy. Enables even faster financial processing (and not just bitcoins....) & other fun stuff.
Click to expand...

http://youtu.be/2CPC0cCagOE?t=46s
 
I like the vacuum-tube clocks with Nixie displays.
 
Terry said:
Temperature and humidity make a lot of sense.

Thanks everyone,
Terry
Click to expand...


And it might not be the clocks mechanism either... The floor it sits on could heave a little over each season and cause the same problem..:confused:
 
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