Re: [time-nuts] Regulating a pendulum clock

In my post below I didn't understand how a constant electromagnet on the side of the pendulum could adjust the pendulum rate. Well I've worked it out. Despite common misconceptions pendulum swing rate is not independent of amplitude. It is to the first order but not when calculated properly. The

Re: [time-nuts] Regulating a pendulum clock

Food for thought. I find it interesting that no one has suggested alternatives to improving the performance of a pendulum clock other than controlling it with a higher performance clock. If the goal is a better clock why not attempt to understand the source of the errors and work on

Re: [time-nuts] Regulating a pendulum clock

- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Holmstrom Sent: Monday, August 09, 2010 12:47 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Regulating a pendulum clock Food for thought. I find it interesting that no one has suggested alternatives

Re: [time-nuts] Regulating a pendulum clock

Le 09/08/2010 18:46, Bob Holmstrom a écrit : Food for thought. I find it interesting that no one has suggested alternatives to improving the performance of a pendulum clock other than controlling it with a higher performance clock. If the goal is a better clock why not attempt to

Re: [time-nuts] Regulating a pendulum clock

clock. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook Sent: 09 August 2010 18:21 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating a pendulum clock Le 09/08/2010 18:46, Bob

Re: [time-nuts] Regulating a pendulum clock

cook Sent: 09 August 2010 18:21 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating a pendulum clock Le 09/08/2010 18:46, Bob Holmstrom a écrit : Food for thought. I find it interesting that no one has suggested alternatives to improving

Re: [time-nuts] Regulating a pendulum clock

What happens when the rope breaks? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: 09 August 2010 19:10 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating a pendulum clock You

Re: [time-nuts] Regulating a pendulum clock

can put into a pendulum clock. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook Sent: 09 August 2010 18:21 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating a pendulum clock Le 09/08

Re: [time-nuts] Regulating a pendulum clock

August 2010 19:10 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating a pendulum clock You could put a large mass of concrete or somehing above the clock and crank it up and down, to balance out the computed gravity changes. :) -John

Re: [time-nuts] Regulating a pendulum clock

: [time-nuts] Regulating a pendulum clock What happens when the rope breaks? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: 09 August 2010 19:10 To: Discussion of precise time and frequency measurement Subject: Re: [time

Re: [time-nuts] Regulating a pendulum clock

: Monday, August 09, 2010 1:17 PM To: j...@quik.com; 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Regulating a pendulum clock What happens when the rope breaks? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf

Re: [time-nuts] Regulating a pendulum clock

put into a pendulum clock. -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook Sent: 09 August 2010 18:21 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating a pendulum clock Le 09/08

Re: [time-nuts] Regulating a pendulum clock

Ahhh, this is more like it! Large gears and thick ropes moving heavy weights up and down. :) Of course, you wouldn't want anything digital doing this. Just a large pendulum clock driving a maze of gears that calculate solar and lunar positions. Bill Hawkins -Original Message- From: J.

Re: [time-nuts] Regulating a pendulum clock

Oh Dear! What have I started? ;-) -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bill Hawkins Sent: 09 August 2010 21:36 To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Regulating a pendulum clock

Re: [time-nuts] Regulating a pendulum clock

Nah! No ropes or gears. Just a SS tank on steel stilts and a big mercury reservoir and a pump. And it might not have to hold tons. Think of a hollow SS donut with the pendulum in the clear space. KISS, -John === Ahhh, this is more like it! Large gears and thick ropes moving

Re: [time-nuts] Regulating a pendulum clock

There are many pieces of technology developed in the 20th century that have not been applied to pendulum clocks. My take on much of the technology is that it is too volatile to be of use in making a better clock. The task is not to keep better time, that has already been done with

Re: [time-nuts] Regulating a pendulum clock

Hi Ian, Unfortunately Gravity is not constant. Pendulum clocks show cyclic errors due to the influences of the Moon's and Sun's Gravitational fields. I forget the amounts but it is in the region of parts in 10 to the 7, which is easily measurable. This limits the compensations one can

Re: [time-nuts] Regulating a pendulum clock

pressure effects. Bob -- From: b...@lysator.liu.se Sent: Monday, August 09, 2010 7:07 PM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Regulating a pendulum clock Hi Ian, Unfortunately

Re: [time-nuts] Regulating a pendulum clock

In principle, there is no real reason a Rb, Cs, ot atomic fountain could not be made to last a very, very long time in a lab. It would certainly be possible to design a source that is either continuously fed from the outside or a pair of sources that can be changed to maintain continuous

Re: [time-nuts] Regulating a pendulum clock

Bob Holmstrom wrote: Food for thought. I find it interesting that no one has suggested alternatives to improving the performance of a pendulum clock other than controlling it with a higher performance clock. If the goal is a better clock why not attempt to understand the source of the

Re: [time-nuts] Regulating a pendulum clock

Bob Camp wrote: Hi For that matter, how hard is it to put it in a vacuum with temperature control? Gets two big issues out of the way pretty fast. We certainly buy crystal oscillators that are heated and enclosed in pressure tight containers (not quite the same as vacuum, but close). Bob

Re: [time-nuts] Regulating a pendulum clock

Ian Sheffield wrote: What happens when the rope breaks? -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: 09 August 2010 19:10 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating

Re: [time-nuts] Regulating a pendulum clock

Javier Herrero wrote: Not so simple... you should move it around in order to balance the gravity force vector :) Regards, Javier two large masses rotating around the pendulum, one synchronized with the sun, one sync'd with the moon. Having just looked up the orrery stuff, a suitable

Re: [time-nuts] Regulating a pendulum clock

Bruce Griffiths wrote: Advisable given the required mass will probably be in the 10-100 ton range. Bruce J. L. Trantham, M. D. wrote: Personally, I would get out of the way. : ) Joe Wait a minute.. is it that big? or is it much, much bigger.. Inverse square is involved. The moon's mass

Re: [time-nuts] Regulating a pendulum clock

I screwed up by a factor of a million.. jimlux wrote: Bruce Griffiths wrote: Advisable given the required mass will probably be in the 10-100 ton range. Bruce J. L. Trantham, M. D. wrote: Personally, I would get out of the way. : ) Joe Wait a minute.. is it that big? or is it much,

Re: [time-nuts] Regulating a pendulum clock

All this talk about regulating a pendulum clock... are you people buying them, building them, or what? I'm interested! I keep thinking about it and something keeps bringing me back to the bob being a neodymium magnet itself. I'm sure you can guess where I'm headed with that... 73 Brice

Re: [time-nuts] Regulating a pendulum clock

-nuts@febo.com Sent: Monday, August 09, 2010 9:53 PM Subject: Re: [time-nuts] Regulating a pendulum clock All this talk about regulating a pendulum clock... are you people buying them, building them, or what? I'm interested! I keep thinking about it and something keeps bringing me back

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

This is very interesting and I wonder if the capabilities of this system being applied to any clock pendulum. If this sort of control any pendulum, then I wonder if it's possible to sync it to some standard. Steve On 08/08/2010, Don Mimlitch donm...@yahoo.com wrote: Jim Said: It also has a coil

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

This is very interesting and I wonder if the capabilities of this system being applied to any clock pendulum. If this sort of control any pendulum, then I wonder if it's possible to sync it to some standard. Steve On 08/08/2010, Don Mimlitch donm...@yahoo.com wrote: Jim Said: It also has a coil

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

Sorry for double post, modem dropped during sending and a refresh on the browser when it was up resent the message. Steve On 08/08/2010, Steve Rooke sar10...@gmail.com wrote: This is very interesting and I wonder if the capabilities of this system being applied to any clock pendulum. If this

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

Not many clocks are set up with the gear to modulate the rate, but they are all still sensitive to injection locking. A tiny rare earth magnet on the pendulum (say 1/2 way down the pendulum rod) and a coil fed with a stretched (say 250ms long) PPS or for a seconds pendulum PP2S pulse will

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

I was rather more thinking of the setup that Don was suggesting as not many domestic clocks have a seconds pendulum and it would otherwise take dividing down a referenced oscillator to the correct frequency. Cheers, Steve On 08/08/2010, Neville Michie namic...@gmail.com wrote: Not many clocks

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

Check out Bryan Mumfords page. http://www.bmumford.com/clocks/em2/index.html Le 08/08/2010 11:14, Steve Rooke a écrit : I was rather more thinking of the setup that Don was suggesting as not many domestic clocks have a seconds pendulum and it would otherwise take dividing down a referenced

Re: [time-nuts] Regulating a pendulum clock

The attached single ended inverting driver is perhaps a better choice as it allows a dc coupled noniverting amplifier with gain and significant offset and drift to be substituted for the LT1010 buffer depicted if the frequency compensation is adjusted to suit. The series RC across the coil

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

On 08/08/2010, mike cook mike.c...@orange.fr wrote: Check out Bryan Mumfords page. http://www.bmumford.com/clocks/em2/index.html I did not want to kick the pendulum with a pulse each swing as the drive would be part and parcel of the existing clock mechanism. What I was interested in was Don

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

Hi all, I think at this point I need to explain the electromagnet positioning. The permanent magnet is on the rod about 25cm down (out of 100cm). The electromagnet is on the left side and so gets close to the permanent magnet every two seconds. Injection locking would be a simple solution and

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

the location of a weight along the pendulum. -RL --- -- From: Steve Rooke sar10...@gmail.com Sent: Sunday, August 08, 2010 7:30 AM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Regulating a pendulum

Re: [time-nuts] Regulating a pendulum clock

:29 PM To: j...@quik.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Regulating a pendulum clock The 60mA load current would be problematic for most common opamps without an output buffer stage. High voltage opamps are relatively rare. Bruce J. Forster wrote

Re: [time-nuts] Regulating a pendulum clock

You are picking very unimportant nits. If there were a small noise spike from the opamp, it'd goose the pendulum a tiny amount. That would be corrected on the next swing. You are turning a trip to the corner store into an Apollo Moon Mission. BTW, since the =drive does not to be bipolar, one of

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

That's why I suggested killing the BW of the opamps in the partial H bridge configuration previously suggested. Transient response is almost unneeded. -John == On 08/08/2010, mike cook mike.c...@orange.fr wrote: Check out Bryan Mumfords page.

Re: [time-nuts] Regulating a pendulum clock

J. Forster wrote: You are picking very unimportant nits. If there were a small noise spike from the opamp, it'd goose the pendulum a tiny amount. That would be corrected on the next swing. Heuristic analysis of this type is counter productive. You are turning a trip to the corner store into

Re: [time-nuts] Regulating a pendulum clock

Hmmm lemme see. I think I'd use a 12 volt supply and two transistors driven by two outputs on my Arduino,basic stamp,picaxe or other whizzie. I'd then implement a PID controller essentially using the 1 sec pulse from the pendulum and the 1 sec pulse from my Rb, satellite receiver, crystal clock,

Re: [time-nuts] Regulating a pendulum clock

No protection against external shorts or other undesired events. Extensive analog filtering to avoid creating an effective radiator of noise may also be necessary. Simple analog techniques are probably simpler/cheaper once the necessary filtering and protection are included. Bruce Don Latham

Re: [time-nuts] Regulating a pendulum clock

fast blow fuse, resonate the coil to the pwm frequency. Parts count small, tinkering in software instead of breathing lead fumes or whatever noxious stuff the Europeans have forced us to use... Don Bruce Griffiths No protection against external shorts or other undesired events. Extensive analog

Re: [time-nuts] Regulating a pendulum clock

Mere fast blow fuses aren't usually precise enough to protect transistors against over current unless one uses rather large transistors. Overcurrent protected drivers are available and readily designed/built. Protection against di/dt transients due to external events is also advisable.

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

Well last night I did a quick and dirty. I got my (GPS locked) 3325B to generate square waves (0-5V) at 1 Hz. 500ms on. 500ms off. I ran this through a relay that delivered 10mA at 25V to the coil. By adjusting the phase of the 3325B I got the ON to occur as the magnets approached. But I had no

Re: [time-nuts] Regulating a pendulum clock

Now I will get myself in a lot of trouble. Why wouldn't a constant pulse at a 2 sec interval essentially lock the pendulum after a bit. If the pulse is always there and occurs just after the mid swing. I suspect you do need to adjust current with a pot to get things settled. But essentially open

Re: [time-nuts] Regulating a pendulum clock

- From: Bruce Griffiths bruce.griffi...@xtra.co.nz To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, August 08, 2010 5:22 PM Subject: Re: [time-nuts] Regulating a pendulum clock Mere fast blow fuses aren't usually precise enough to protect transistors

Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman)

Nice! Don - Original Message - From: Jim Palfreyman jim77...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, August 08, 2010 6:12 PM Subject: Re: [time-nuts] Regulating a pendulum clock (Jim Palfreyman) Well last night I did

Re: [time-nuts] Regulating a pendulum clock

Yep, injection locling works just fine Don - Original Message - From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, August 08, 2010 7:37 PM Subject: Re: [time-nuts] Regulating a pendulum clock Now I will get

Re: [time-nuts] Regulating a pendulum clock

A high voltage opamp (or a low voltage opamp with a discrete output stage with a voltage gain of at least 2) with -3V and + 30V supplies is perhaps the simplest method. The opamp merely senses the current flowing in a current sensing resistor and regulates this voltage drop to equal the output

Re: [time-nuts] Regulating a pendulum clock

Since it's inside a closed loop, the design is uncritical. One option is a high voltage Op-Amp with +/- 25 to 30 VDC supplies. You would set the OA gain to about 10, so 2.5 V in would yield 25 V out. and sum in a negative offset voltage so that +2.5 from the DAC yields 0.0 V out. I'd use

Re: [time-nuts] Regulating a pendulum clock

Hi, the range of the adjustment is probably far wider than you would ever need as you will be applying it continuously instead of over a few hours to correct the clock to the latest observations. So all you need is an amplifier run off + and - 15 Volts with enough gain for the DAC output.

Re: [time-nuts] Regulating a pendulum clock

The 60mA load current would be problematic for most common opamps without an output buffer stage. High voltage opamps are relatively rare. Bruce J. Forster wrote: Since it's inside a closed loop, the design is uncritical. One option is a high voltage Op-Amp with +/- 25 to 30 VDC supplies.

Re: [time-nuts] Regulating a pendulum clock

A high voltage opamp (or a low voltage opamp with a discrete output stage with a voltage gain of at least 2) with -3V and + 30V supplies is perhaps the simplest method. The opamp merely senses the current flowing in a current sensing resistor and regulates this voltage drop to equal the output

Re: [time-nuts] Regulating a pendulum clock

OK. You know better. BTW, op-amp noise is essentially irrelevant in this application, and the C's across the FB resistors limit slew rates so there is no significant dI/dt to cause voltage spikes. -John Your naive stabilisation scheme wont work, try simulating it. 741's are

Re: [time-nuts] Regulating a pendulum clock

J. Forster wrote: OK. You know better. BTW, op-amp noise is essentially irrelevant in this application, and the C's across the FB resistors limit slew rates so there is no significant dI/dt to cause voltage spikes. Noise is never irrelevant. You havent shown that its insignificant either.