Re: [time-nuts] A different timenuts interest
Another perspective on time: http://www.longnow.org/clock/ And some fascinating mechanical stuff. The mechanical branch of time-nuts. They have an office, show-room, museum, store, whatever in Fort Mason in San Francisco. If you like neat mechanical stuff, it's well worth a trip. It's art as well as a clock. http://www.longnow.org/contact/ (The map/picture is looking southeast from over the Golden Gate Bridge.) -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hi How much room do you have for the pendulum? Size is going to impact the choice of designs quite a bit. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris Odell Sent: Thursday, July 22, 2010 11:21 PM To: time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest Hi all, I would like to thank everyone who responded to my post. This is a wonderful group of talented and erudite people and it was a pleasure to read the posts (and private emails) on the subject of the Foucault pendulum. Where else could the discussion range over timekeeping, mechanical suspension arrangements, Tesla coils, Napoleon, sustaining systems, blades on the pendulum bob, a host of references and all the other great stuff that turned up. This project is for a FP that will be part of an art installation. It's unlikely to be permanent though unless a major gallery or collector likes the work enough to buy it. Unfortunately this rules out commercial systems costing tens of thousands of dollars. From my readings and suggestions from members of this group I have come to understand the following: The main issues in designing a FP are the sustaining system, avoidance or damping of elliptical motion and safety considerations in case the wire breaks. Of course keeping fingers and draughts away is also a consideration. Sustaining systems are mostly electromagnetic, either with a ring shaped electromagnet at the top near the suspension point controlled by optical sensors, or one or more coils below the centre point with a magnet on the bob. This acts as both a sensor and motor. There is also a reluctance type driver described using mains frequency solenoids. The most elegant system is the parametric one where the suspension point is oscillated up and down sinusoidally at twice the pendulum frequency and there are no horizontal forces acting on the bob at all. I found a very complex mathematical analysis if that. It would be an interesting challenge using optical sensors and a stepper perhaps to move a cam or crank to realise that. Avoidance of elliptical motion and increasing the Q of the oscillator is one of the reasons why most FPs are so long with heavy bobs. Despite this I found some articles on short FPs, including one hanging from the wall and used as a clock with a pendulum less than a metre long. Elliptical movement is often controlled by a Charron ring which interacts with the wire to limit ellipsoidal movement. There are also magnetic eddy current damping systems described and one elegant method which uses a precisely timed pulsed sustaining system to cancel elliptical motion. As was pointed out, FPs are not primarily time keeping devices but there is a relationship between the period of their precession and the rotation of the planet, which is also dependent on Latitude. Perhaps unsurprisingly, someone has described a FP clock which required an electronic system to stop it for a few hours in the middle of the night to sync its movement to the 24 hour cycle. One can easily see GPS control creeping in there :-) I hope the discussion continues, It's been great so far. I'll keep the group posted on progress. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
On 07/22/2010 02:13 AM, Morris Odell wrote: The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. As a kid, I did a self sustaining pendulum with no moving parts and no magnets: The bob was suspended by two parallel wires, lacquered together, and shorted at the bob end. As the bob passed over the center, a one-shot sent a good-sized current pulse through the wire, heating it, making it slightly longer, and then shrink again as it cooled at the outside of the swing. For a heavy pendulum, and thick wire, the time constant in the cooling phase will likely make this infeasible. /Kasper Pedersen ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
The Exploratorium at The Palace of Fine Arts in San Francisco had one of these, and may still have it. I haven't been there in a while and don't know the details. Nuts Volts had a construction project for a continuously swinging pendulum in their September 2009 issue. It had a magnet at the end of the pendulum which generated a current in a coil mounted in the center of the base. A simple 2-transistor circuit would sense the pendulum swing and would generate a pulse in the same coil to accelerate the pendulum and keep it swinging in infinity, or until the battery died, whichever came first. Have you looked for ideas on Bryan Mumford's website? -- FL --- Den ons 21/7/10 skrev Morris Odell vilgo...@bigpond.net.au: Fra: Morris Odell vilgo...@bigpond.net.au Emne: [time-nuts] A different timenuts interest Til: time-nuts@febo.com Dato: onsdag 21. juli 2010 17.13 Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
On Wed, Jul 21, 2010 at 10:40:48PM -0400, Bob Bownes wrote: Silly me, I just realized you need to compensate for the change in length with temperature. You could use an Invar wire. This sounds like a great project! On Wed, Jul 21, 2010 at 10:26 PM, Bob Bownes bow...@gmail.com wrote: There is at least one in DC, at the Smithsonian iirc. RPI, where I went to college, had one in the 3 story stairwell in the library. Don't know if it is still there. I remember one someplace in London too. Someone mentioned temperature compensation. What would you need to compensate for? Temp change in the wire wouldn't effect the rotation as far as I can tell. Swing length might be different based on temp of the wire I guess, but with a long pendulum, I think the magnet is going to way overcome that issue. The one @ RPI had issues due to air movement in the shaft, but that's a different problem. I suppose the right method is to use a GPS disciplined oscillator and the appropriate divider to drive the magnet under the floor. :) To cut down in draft induced drift and jitter, you'd have to put the whole thing in a vacuum though! On Wed, Jul 21, 2010 at 10:13 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: Hal Murray wrote: Several years ago, I found a web site for a commercial place that made them for museums. (I forget why I was looking for that sort of stuff.) You might find interesting stuff/ideas via google but I didn't find a similar site with a bit of searching. The Museum of Science and Industry in Chicago had one when I lived there in the 1960's. Rick N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Eugen* Leitl a href=http://leitl.org;leitl/a http://leitl.org __ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
On Wed, Jul 21, 2010 at 7:57 PM, J. Forster j...@quik.com wrote: I remember one someplace in London too. Science Museum in South Kensington, I'd expect, but I've not been there 20+ years. Yes, they have one in one of their open multi-storey stairwells. If I remember correctly, the energy input is provided by lifting and lowering the pivot point slightly in sync with the swing, rather than anything done at the bob end. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
http://www.astro.louisville.edu/foucault/pendulum.pdf is one of the best references I have in my bookmarks. Matthew Kaufman ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hi Morris: See: http://www.calacademy.org/products/pendulum/pendulum_sales.html http://www.calacademy.org/products/pendulum/pendspec.pdf they are not cheap, but a proven design and probably lower in cost than making just one of them. One of these was working at Foothill College in Los Altos Hills, California when I was there. It was outside in a combined pit and tower, but is not longer in use. It needs to be somewhere inside where vandals can not get to it. Have Fun, Brooke Clarke http://www.PRC68.com Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Eugen Leitl wrote: On Wed, Jul 21, 2010 at 10:40:48PM -0400, Bob Bownes wrote: Silly me, I just realized you need to compensate for the change in length with temperature. You could use an Invar wire. Some insight from a friend (a proto-timenut) who was thinking about building a 1ppm free pendulum in air for a fancy grandfather clock. Invar (aside from being expensive) isn't appropriate here, depending on the design. Its low CTE properties depend on not being mechanically stressed. A better scheme is the traditional bimetal pendulum compensation approach of steel rod and brass bob that can slide along the rod. You pick the dimensions so that as the steel gets longer, the bob expands at a different rate (pushing the CG back up), so that the net movement in CG position is zero. You change the relative diameters of the two metal parts to get the CTEs and movement to balance out. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
IIRC, there was a large one at Weston Observatory (Boston College). But, it has been 40+ years since I was last there. 73, Dick, W1KSZ -Original Message- From: Flemming Larsen oz...@yahoo.dk Sent: Jul 22, 2010 1:47 AM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest The Exploratorium at The Palace of Fine Arts in San Francisco had one of these, and may still have it. I haven't been there in a while and don't know the details. Nuts Volts had a construction project for a continuously swinging pendulum in their September 2009 issue. It had a magnet at the end of the pendulum which generated a current in a coil mounted in the center of the base. A simple 2-transistor circuit would sense the pendulum swing and would generate a pulse in the same coil to accelerate the pendulum and keep it swinging in infinity, or until the battery died, whichever came first. Have you looked for ideas on Bryan Mumford's website? -- FL --- Den ons 21/7/10 skrev Morris Odell vilgo...@bigpond.net.au: Fra: Morris Odell vilgo...@bigpond.net.au Emne: [time-nuts] A different timenuts interest Til: time-nuts@febo.com Dato: onsdag 21. juli 2010 17.13 Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hi At $30K certainly not cheap. My guess is that the building modifications and permits will set you back a pretty significant chunk of money as well. The issue of troubleshooting a 6 story high machine in a public space (plus insurance issues) likely makes the proven design a much better decision than a one off. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 22, 2010 10:38 AM To: Discussion of precise time and frequency measurement Cc: Morris Odell Subject: Re: [time-nuts] A different timenuts interest Hi Morris: See: http://www.calacademy.org/products/pendulum/pendulum_sales.html http://www.calacademy.org/products/pendulum/pendspec.pdf they are not cheap, but a proven design and probably lower in cost than making just one of them. One of these was working at Foothill College in Los Altos Hills, California when I was there. It was outside in a combined pit and tower, but is not longer in use. It needs to be somewhere inside where vandals can not get to it. Have Fun, Brooke Clarke http://www.PRC68.com Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
How about putting a high voltage, high frequency on the bob and wire, so any body part that gets within say 2 feet draws giant arcs? :)) -John === Well, I thought it was interesting that a barrier was needed at least 3 feet away from the swing so that people would not grab the cable. Can you imagine the effect of grabbing the cable with a 250 pound bob attached? I'd build one called Evolution in Action. Put a Poe-like blade on the bottom of the ball and omit the railing. That is, if I had the money, ah, and the building. And my own country, where allowing idiots to breed was illegal. Bill Hawkins -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Thursday, July 22, 2010 11:53 AM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] A different timenuts interest Hi At $30K certainly not cheap. My guess is that the building modifications and permits will set you back a pretty significant chunk of money as well. The issue of troubleshooting a 6 story high machine in a public space (plus insurance issues) likely makes the proven design a much better decision than a one off. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 22, 2010 10:38 AM To: Discussion of precise time and frequency measurement Cc: Morris Odell Subject: Re: [time-nuts] A different timenuts interest Hi Morris: See: http://www.calacademy.org/products/pendulum/pendulum_sales.html http://www.calacademy.org/products/pendulum/pendspec.pdf they are not cheap, but a proven design and probably lower in cost than making just one of them. One of these was working at Foothill College in Los Altos Hills, California when I was there. It was outside in a combined pit and tower, but is not longer in use. It needs to be somewhere inside where vandals can not get to it. Have Fun, Brooke Clarke http://www.PRC68.com Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Well, I thought it was interesting that a barrier was needed at least 3 feet away from the swing so that people would not grab the cable. Can you imagine the effect of grabbing the cable with a 250 pound bob attached? I'd build one called Evolution in Action. Put a Poe-like blade on the bottom of the ball and omit the railing. That is, if I had the money, ah, and the building. And my own country, where allowing idiots to breed was illegal. Bill Hawkins -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Thursday, July 22, 2010 11:53 AM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] A different timenuts interest Hi At $30K certainly not cheap. My guess is that the building modifications and permits will set you back a pretty significant chunk of money as well. The issue of troubleshooting a 6 story high machine in a public space (plus insurance issues) likely makes the proven design a much better decision than a one off. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 22, 2010 10:38 AM To: Discussion of precise time and frequency measurement Cc: Morris Odell Subject: Re: [time-nuts] A different timenuts interest Hi Morris: See: http://www.calacademy.org/products/pendulum/pendulum_sales.html http://www.calacademy.org/products/pendulum/pendspec.pdf they are not cheap, but a proven design and probably lower in cost than making just one of them. One of these was working at Foothill College in Los Altos Hills, California when I was there. It was outside in a combined pit and tower, but is not longer in use. It needs to be somewhere inside where vandals can not get to it. Have Fun, Brooke Clarke http://www.PRC68.com Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Wouldn't that affect the path of the pendulum by interacting with the Earth's magnetic field? :) J. Forster wrote: How about putting a high voltage, high frequency on the bob and wire, so any body part that gets within say 2 feet draws giant arcs? :)) -John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
The Griffith Park exhibit did include a Tesla Coil. Hm... Don J. Forster How about putting a high voltage, high frequency on the bob and wire, so any body part that gets within say 2 feet draws giant arcs? :)) -John === Well, I thought it was interesting that a barrier was needed at least 3 feet away from the swing so that people would not grab the cable. Can you imagine the effect of grabbing the cable with a 250 pound bob attached? I'd build one called Evolution in Action. Put a Poe-like blade on the bottom of the ball and omit the railing. That is, if I had the money, ah, and the building. And my own country, where allowing idiots to breed was illegal. Bill Hawkins -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Thursday, July 22, 2010 11:53 AM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] A different timenuts interest Hi At $30K certainly not cheap. My guess is that the building modifications and permits will set you back a pretty significant chunk of money as well. The issue of troubleshooting a 6 story high machine in a public space (plus insurance issues) likely makes the proven design a much better decision than a one off. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, July 22, 2010 10:38 AM To: Discussion of precise time and frequency measurement Cc: Morris Odell Subject: Re: [time-nuts] A different timenuts interest Hi Morris: See: http://www.calacademy.org/products/pendulum/pendulum_sales.html http://www.calacademy.org/products/pendulum/pendspec.pdf they are not cheap, but a proven design and probably lower in cost than making just one of them. One of these was working at Foothill College in Los Altos Hills, California when I was there. It was outside in a combined pit and tower, but is not longer in use. It needs to be somewhere inside where vandals can not get to it. Have Fun, Brooke Clarke http://www.PRC68.com Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
As a number of examples have been referenced in the reply to the original post, I will add a note on one of pendulums that Foucault himself constructed. Foucaults original experiments used shortish cables, but Napoleon wanted a more prestigeous affaire. It was originally installed by Foucault in the Panthéon in Paris in 1851, but was moved from there in 1855 to the Musée des Arts et Métiers where it has been ever since. In the doc I found it appears that the original cable has been used since then. The sphere : * steel, brass, lead . * diameter = 18 cm. * mass = 28 Kg. The wire : * steel. * lenght = 18 m * has used since 1855. The oscillation period of the Foucault's pendulum of the museum is 8,5 s and is apparent complete rotation occurs in 31,78 h = 31h 47 min at the latitude 48° 50 '. Unfortunately the cable reached its sell by date on the 18th May this year when it broke, dropping the ball on the marble floor , denting it. Most unfortunate. Le 22/07/2010 04:02, Donald Henderickx a écrit : On 7/21/2010 7:13 PM, Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Hello Morris: You might contact Fermi National Accelerator Lab in Batavia Illinois at www.fnal.gov . There Foucault pendulum is sixteen stories from the suspension point to the atrium floor,it's impulse device is buried in the sand under the bob. They may even have a picture of it on there web site. Try the public information office they should be able to get in contact with the people that maintain it. If you are unable to get any help let me know as I might have some contacts there that would help. Good Luck Don Henderickx ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Unfortunately the cable reached its sell by date on the 18th May this year when it broke, dropping the ball on the marble floor , denting it. Most unfortunate. Denting the bob or the marble floor? :) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
I thought that might have caused some confusion ;) . The bob, of course. I guess it can be replaced, but it is a shame that as a historical instrument, it could not have been better cared for. All is not lost though, as one of his smaller original pendulums is swinging in the Panthéon it seems. Le 22/07/2010 21:29, Bob Bownes a écrit : Unfortunately the cable reached its sell by date on the 18th May this year when it broke, dropping the ball on the marble floor , denting it. Most unfortunate. Denting the bob or the marble floor? :) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hi I assume that was Napoleon III rather than the original (I'd hate to see the time-nuts list get banned by the French History Police). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook Sent: Thursday, July 22, 2010 3:27 PM To: time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest As a number of examples have been referenced in the reply to the original post, I will add a note on one of pendulums that Foucault himself constructed. Foucaults original experiments used shortish cables, but Napoleon wanted a more prestigeous affaire. It was originally installed by Foucault in the Panthéon in Paris in 1851, but was moved from there in 1855 to the Musée des Arts et Métiers where it has been ever since. In the doc I found it appears that the original cable has been used since then. The sphere : * steel, brass, lead . * diameter = 18 cm. * mass = 28 Kg. The wire : * steel. * lenght = 18 m * has used since 1855. The oscillation period of the Foucault's pendulum of the museum is 8,5 s and is apparent complete rotation occurs in 31,78 h = 31h 47 min at the latitude 48° 50 '. Unfortunately the cable reached its sell by date on the 18th May this year when it broke, dropping the ball on the marble floor , denting it. Most unfortunate. Le 22/07/2010 04:02, Donald Henderickx a écrit : On 7/21/2010 7:13 PM, Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Hello Morris: You might contact Fermi National Accelerator Lab in Batavia Illinois at www.fnal.gov . There Foucault pendulum is sixteen stories from the suspension point to the atrium floor,it's impulse device is buried in the sand under the bob. They may even have a picture of it on there web site. Try the public information office they should be able to get in contact with the people that maintain it. If you are unable to get any help let me know as I might have some contacts there that would help. Good Luck Don Henderickx ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
time-n...@kasperkp.dk said: As a kid, I did a self sustaining pendulum with no moving parts and no magnets: The bob was suspended by two parallel wires, lacquered together, and shorted at the bob end. As the bob passed over the center, a one-shot sent a good-sized current pulse through the wire, heating it, making it slightly longer, and then shrink again as it cooled at the outside of the swing. Neat. Thanks. For a heavy pendulum, and thick wire, the time constant in the cooling phase will likely make this infeasible. That sounds like a good excuse to build a bigger and more impressive pendulum. You need a longer wire so it has a longer period and enough time to cool off. Does anybody know how much piezo positioners cost, or where to get them cheap? I'm not looking for a fancy gizmo that takes many tiny steps, just a something simple that will vary the height slightly. Maybe build one from several piezo noisemakers. Here is the fun part. You can also use it as a sensor to measure the position. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
I also think so, but Time-nuts are nuts about attoseconds, not decades... ;-} Jean-Louis Oneto - Original Message - From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thursday, July 22, 2010 8:03 PM Subject: Re: [time-nuts] A different timenuts interest Hi I assume that was Napoleon III rather than the original (I'd hate to see the time-nuts list get banned by the French History Police). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook Sent: Thursday, July 22, 2010 3:27 PM To: time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest As a number of examples have been referenced in the reply to the original post, I will add a note on one of pendulums that Foucault himself constructed. Foucaults original experiments used shortish cables, but Napoleon wanted a more prestigeous affaire. It was originally installed by Foucault in the Panthéon in Paris in 1851, but was moved from there in 1855 to the Musée des Arts et Métiers where it has been ever since. In the doc I found it appears that the original cable has been used since then. The sphere : * steel, brass, lead . * diameter = 18 cm. * mass = 28 Kg. The wire : * steel. * lenght = 18 m * has used since 1855. The oscillation period of the Foucault's pendulum of the museum is 8,5 s and is apparent complete rotation occurs in 31,78 h = 31h 47 min at the latitude 48° 50 '. Unfortunately the cable reached its sell by date on the 18th May this year when it broke, dropping the ball on the marble floor , denting it. Most unfortunate. Le 22/07/2010 04:02, Donald Henderickx a écrit : On 7/21/2010 7:13 PM, Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Hello Morris: You might contact Fermi National Accelerator Lab in Batavia Illinois at www.fnal.gov . There Foucault pendulum is sixteen stories from the suspension point to the atrium floor,it's impulse device is buried in the sand under the bob. They may even have a picture of it on there web site. Try the public information office they should be able to get in contact with the people that maintain it. If you are unable to get any help let me know as I might have some contacts there that would help. Good Luck Don Henderickx ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Actually, I think you can find a time-nut for any span of time, sub-nanosecond to leap seconds, to leap years, to ... John WA4WDL -- From: Jean-Louis Oneto jean-louis.on...@obs-azur.fr Sent: Thursday, July 22, 2010 7:11 PM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest I also think so, but Time-nuts are nuts about attoseconds, not decades... ;-} Jean-Louis Oneto - Original Message - From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thursday, July 22, 2010 8:03 PM Subject: Re: [time-nuts] A different timenuts interest Hi I assume that was Napoleon III rather than the original (I'd hate to see the time-nuts list get banned by the French History Police). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of mike cook Sent: Thursday, July 22, 2010 3:27 PM To: time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest As a number of examples have been referenced in the reply to the original post, I will add a note on one of pendulums that Foucault himself constructed. Foucaults original experiments used shortish cables, but Napoleon wanted a more prestigeous affaire. It was originally installed by Foucault in the Panthéon in Paris in 1851, but was moved from there in 1855 to the Musée des Arts et Métiers where it has been ever since. In the doc I found it appears that the original cable has been used since then. The sphere : * steel, brass, lead . * diameter = 18 cm. * mass = 28 Kg. The wire : * steel. * lenght = 18 m * has used since 1855. The oscillation period of the Foucault's pendulum of the museum is 8,5 s and is apparent complete rotation occurs in 31,78 h = 31h 47 min at the latitude 48° 50 '. Unfortunately the cable reached its sell by date on the 18th May this year when it broke, dropping the ball on the marble floor , denting it. Most unfortunate. Le 22/07/2010 04:02, Donald Henderickx a écrit : On 7/21/2010 7:13 PM, Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Hello Morris: You might contact Fermi National Accelerator Lab in Batavia Illinois at www.fnal.gov . There Foucault pendulum is sixteen stories from the suspension point to the atrium floor,it's impulse device is buried in the sand under the bob. They may even have a picture of it on there web site. Try the public information office they should be able to get in contact with the people that maintain it. If you are unable to get any help let me know as I might have some contacts there that would help. Good Luck Don Henderickx ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hmmm. I thought time-nuts were nuts about time, with branch interests in accuracy, resolution, history... On 7/22/2010 6:24 PM, jmfranke wrote: Actually, I think you can find a time-nut for any span of time, sub-nanosecond to leap seconds, to leap years, to ... John WA4WDL -- From: Jean-Louis Oneto jean-louis.on...@obs-azur.fr Sent: Thursday, July 22, 2010 7:11 PM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest I also think so, but Time-nuts are nuts about attoseconds, not decades... ;-} Jean-Louis Oneto - Original Message - From: Bob Camp li...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thursday, July 22, 2010 8:03 PM Subject: Re: [time-nuts] A different timenuts interest Hi I assume that was Napoleon III rather than the original (I'd hate to see the time-nuts list get banned by the French History Police). Bob -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
On 07/23/2010 01:54 AM, Oz-in-DFW wrote: Hmmm. I thought time-nuts were nuts about time, with branch interests in accuracy, resolution, history... History is nanoseconds ago. Recent history is picoseconds ago. Just now is femtoseconds ago. Fraction of mind ago is attoseconds ago. Acient history is microseconds ago. Ages is microseconds ago Major epochs in time i seconds ago. Geological short period is minutes ago. Geological epoch period is hours ago. No? Cheers, Magnus On 7/22/2010 6:24 PM, jmfranke wrote: Actually, I think you can find a time-nut for any span of time, sub-nanosecond to leap seconds, to leap years, to ... John WA4WDL -- From: Jean-Louis Onetojean-louis.on...@obs-azur.fr Sent: Thursday, July 22, 2010 7:11 PM To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] A different timenuts interest I also think so, but Time-nuts are nuts about attoseconds, not decades... ;-} Jean-Louis Oneto - Original Message - From: Bob Campli...@rtty.us To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Sent: Thursday, July 22, 2010 8:03 PM Subject: Re: [time-nuts] A different timenuts interest Hi I assume that was Napoleon III rather than the original (I'd hate to see the time-nuts list get banned by the French History Police). Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Magnus Danielson wrote: On 07/23/2010 01:54 AM, Oz-in-DFW wrote: Hmmm. I thought time-nuts were nuts about time, with branch interests in accuracy, resolution, history... History is nanoseconds ago. Recent history is picoseconds ago. Just now is femtoseconds ago. Fraction of mind ago is attoseconds ago. Acient history is microseconds ago. Ages is microseconds ago Major epochs in time i seconds ago. Geological short period is minutes ago. Geological epoch period is hours ago. No? Neurons just don't work that fast. Just now is still milliseconds, and then there's all the time-reordering that happens in your brain to make the skew make sense... Matthew Kaufman ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Matthew, On 07/23/2010 02:15 AM, Matthew Kaufman wrote: Magnus Danielson wrote: On 07/23/2010 01:54 AM, Oz-in-DFW wrote: Hmmm. I thought time-nuts were nuts about time, with branch interests in accuracy, resolution, history... History is nanoseconds ago. Recent history is picoseconds ago. Just now is femtoseconds ago. Fraction of mind ago is attoseconds ago. Acient history is microseconds ago. Ages is microseconds ago Major epochs in time i seconds ago. Geological short period is minutes ago. Geological epoch period is hours ago. No? Neurons just don't work that fast. Just now is still milliseconds, and then there's all the time-reordering that happens in your brain to make the skew make sense... It was meant as a joke... When working on modern digital electronics and multi-gigabit links time-scales becomes somewhat shifted and 1 ms becomes a minor eternity. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
E A Foucalt Pendulum is not about time! It's about motion in inertial space. -John === Matthew, On 07/23/2010 02:15 AM, Matthew Kaufman wrote: Magnus Danielson wrote: On 07/23/2010 01:54 AM, Oz-in-DFW wrote: Hmmm. I thought time-nuts were nuts about time, with branch interests in accuracy, resolution, history... History is nanoseconds ago. Recent history is picoseconds ago. Just now is femtoseconds ago. Fraction of mind ago is attoseconds ago. Acient history is microseconds ago. Ages is microseconds ago Major epochs in time i seconds ago. Geological short period is minutes ago. Geological epoch period is hours ago. No? Neurons just don't work that fast. Just now is still milliseconds, and then there's all the time-reordering that happens in your brain to make the skew make sense... It was meant as a joke... When working on modern digital electronics and multi-gigabit links time-scales becomes somewhat shifted and 1 ms becomes a minor eternity. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Another perspective on time: http://www.longnow.org/clock/ And some fascinating mechanical stuff. -Demian Message: 4 Date: Fri, 23 Jul 2010 02:11:04 +0200 From: Magnus Danielson mag...@rubidium.dyndns.org Subject: Re: [time-nuts] A different timenuts interest To: Discussion of precise time and frequency measurement time-nuts@febo.com Message-ID: 4c48de18.7040...@rubidium.dyndns.org Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 07/23/2010 01:54 AM, Oz-in-DFW wrote: Hmmm. I thought time-nuts were nuts about time, with branch interests in accuracy, resolution, history... History is nanoseconds ago. Recent history is picoseconds ago. Just now is femtoseconds ago. Fraction of mind ago is attoseconds ago. Acient history is microseconds ago. Ages is microseconds ago Major epochs in time i seconds ago. Geological short period is minutes ago. Geological epoch period is hours ago. No? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
J. Forster wrote: E A Foucalt Pendulum is not about time! It's about motion in inertial space. are they not the same, underneath it all? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hi all, I would like to thank everyone who responded to my post. This is a wonderful group of talented and erudite people and it was a pleasure to read the posts (and private emails) on the subject of the Foucault pendulum. Where else could the discussion range over timekeeping, mechanical suspension arrangements, Tesla coils, Napoleon, sustaining systems, blades on the pendulum bob, a host of references and all the other great stuff that turned up. This project is for a FP that will be part of an art installation. It's unlikely to be permanent though unless a major gallery or collector likes the work enough to buy it. Unfortunately this rules out commercial systems costing tens of thousands of dollars. From my readings and suggestions from members of this group I have come to understand the following: The main issues in designing a FP are the sustaining system, avoidance or damping of elliptical motion and safety considerations in case the wire breaks. Of course keeping fingers and draughts away is also a consideration. Sustaining systems are mostly electromagnetic, either with a ring shaped electromagnet at the top near the suspension point controlled by optical sensors, or one or more coils below the centre point with a magnet on the bob. This acts as both a sensor and motor. There is also a reluctance type driver described using mains frequency solenoids. The most elegant system is the parametric one where the suspension point is oscillated up and down sinusoidally at twice the pendulum frequency and there are no horizontal forces acting on the bob at all. I found a very complex mathematical analysis if that. It would be an interesting challenge using optical sensors and a stepper perhaps to move a cam or crank to realise that. Avoidance of elliptical motion and increasing the Q of the oscillator is one of the reasons why most FPs are so long with heavy bobs. Despite this I found some articles on short FPs, including one hanging from the wall and used as a clock with a pendulum less than a metre long. Elliptical movement is often controlled by a Charron ring which interacts with the wire to limit ellipsoidal movement. There are also magnetic eddy current damping systems described and one elegant method which uses a precisely timed pulsed sustaining system to cancel elliptical motion. As was pointed out, FPs are not primarily time keeping devices but there is a relationship between the period of their precession and the rotation of the planet, which is also dependent on Latitude. Perhaps unsurprisingly, someone has described a FP clock which required an electronic system to stop it for a few hours in the middle of the night to sync its movement to the 24 hour cycle. One can easily see GPS control creeping in there :-) I hope the discussion continues, It's been great so far. I'll keep the group posted on progress. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
The problem is straight forward, except for sensing the position of the pendulum so the impulse is applied at the correct phase. There must be a bunch of published designs, but if I were to try it, I'd use something optical or capacitive. For optical, I'd put a annular ring of IR LED/Phototransistor assemblies around the center, wired OR the outputs, and use the signal to trigger the impulse. The bottom of the pendulum should be polished or mirrored. For capacitive, I'd copy a proximity detector circuit and use that. One plate would be the pendulum, the other an annular conducting ring just below it. It might also work with two, concentric rings and an electrically isolated pendulum. Best, -John === Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
On 07/22/2010 02:13 AM, Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Just as you slightly push away the bob you could also attract it as it comes back... then you get a push-pull action. A coil in the center would have a fairly low plane-shifting action. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
At 08:13 PM 7/21/2010, Morris Odell wrote... Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Scientific American, back in June 1958, covered many details of Foucault pendulums, from Charron pivots to drive systems. The article was later reprinted in The Amateur Scientist book. It describes a magnetic drive which applies force near the pivot and another which sits underneath the pendulum. There's also a mechanical drive, as described near the bottom of this page: http://science-design.com/pages/foucault_pendulum_background/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hi If you use the mechanical system (raise and lower the pivot point): Can you use the strain on the pivot to get the location information? Bob On Jul 21, 2010, at 8:53 PM, Mike S wrote: At 08:13 PM 7/21/2010, Morris Odell wrote... Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Scientific American, back in June 1958, covered many details of Foucault pendulums, from Charron pivots to drive systems. The article was later reprinted in The Amateur Scientist book. It describes a magnetic drive which applies force near the pivot and another which sits underneath the pendulum. There's also a mechanical drive, as described near the bottom of this page: http://science-design.com/pages/foucault_pendulum_background/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
... Foucault pendulum ... Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Several years ago, I found a web site for a commercial place that made them for museums. (I forget why I was looking for that sort of stuff.) You might find interesting stuff/ideas via google but I didn't find a similar site with a bit of searching. -- Here is what I would try: Put a magnet on the bottom of the pendulum. Put a coil below it. (obviously centered) Use the coil as a sensor to measure the timing. Use the coil as a motor to pull the pendulum every N-th swing. The question is how accurately centered do the magnet and coil have to be? I don't know. It sounds like a fun mixture of theory and engineering. One of the variables is how far away is the pendulum when you are pulling. The farther away it is, the smaller angle you have from the ideal. You can change that by varying the start/stop times on the pull pulse. I'd probably put the coil on a crude X-Y table, set it up as good as I could, then see if it worked. Then I would deliberately move it off a bit and see what happened. Or try to servo it to the best place, probably by manual changes every day or week or ??? I'm assuming this is for a school or museum. The required positional accuracy is actually a real science experiment. The idea of experiment to test an idea is more important than the basic Foucault pendulum itself so you get two exhibits in one. Of course, another question is how fast does it decay? Or rather, how long will it run with no energy input? This says 2 hours: http://www.cmnh.org/site/AtTheMuseum/OnExhibit/PermanentExhibits/Foucault.as px for a 270 lb bob, but I don't know how tall that is. (But it says 6.2 seconds, so I should be able to calculate it.) -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
On 7/21/2010 7:13 PM, Morris Odell wrote: Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Hello Morris: You might contact Fermi National Accelerator Lab in Batavia Illinois at www.fnal.gov . There Foucault pendulum is sixteen stories from the suspension point to the atrium floor,it's impulse device is buried in the sand under the bob. They may even have a picture of it on there web site. Try the public information office they should be able to get in contact with the people that maintain it. If you are unable to get any help let me know as I might have some contacts there that would help. Good Luck Don Henderickx ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Griffith Park in LA operates a Foucault pendulum that's been going for at least 70 years (don't ask how I know). They might have a writeup somewhere. I think te pivot was a simple clamp holding the piano wire. You'd think it would fail from stress, but the pendulum is very long, so the angle of the swing is very small. I think the drive actually was done close to the pivot via a magnet on the wire rather than at the bottom. To start the pendulum off, a string was tied to hold the pendulum cocked and the string simply burned with a match. A perfect no-torque start... A simple optical interruptor driving something like a basic stamp and a ring electromagnet with a PM on the support wire will allow proper timing. You will be surprised at how little energy is required to keep it going; it can be roughly calculated from the ball diameter. The beauty of this system is that the exact frequency of the pendulum is not important. First order temperature correction can be done in the microprocessor. Send some pix when you get it going... Don Latham. Hal Murray ... Foucault pendulum ... Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Several years ago, I found a web site for a commercial place that made them for museums. (I forget why I was looking for that sort of stuff.) You might find interesting stuff/ideas via google but I didn't find a similar site with a bit of searching. -- Here is what I would try: Put a magnet on the bottom of the pendulum. Put a coil below it. (obviously centered) Use the coil as a sensor to measure the timing. Use the coil as a motor to pull the pendulum every N-th swing. The question is how accurately centered do the magnet and coil have to be? I don't know. It sounds like a fun mixture of theory and engineering. One of the variables is how far away is the pendulum when you are pulling. The farther away it is, the smaller angle you have from the ideal. You can change that by varying the start/stop times on the pull pulse. I'd probably put the coil on a crude X-Y table, set it up as good as I could, then see if it worked. Then I would deliberately move it off a bit and see what happened. Or try to servo it to the best place, probably by manual changes every day or week or ??? I'm assuming this is for a school or museum. The required positional accuracy is actually a real science experiment. The idea of experiment to test an idea is more important than the basic Foucault pendulum itself so you get two exhibits in one. Of course, another question is how fast does it decay? Or rather, how long will it run with no energy input? This says 2 hours: http://www.cmnh.org/site/AtTheMuseum/OnExhibit/PermanentExhibits/Foucault.as px for a 270 lb bob, but I don't know how tall that is. (But it says 6.2 seconds, so I should be able to calculate it.) -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind. R. Bacon Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Hal Murray wrote: Several years ago, I found a web site for a commercial place that made them for museums. (I forget why I was looking for that sort of stuff.) You might find interesting stuff/ideas via google but I didn't find a similar site with a bit of searching. The Museum of Science and Industry in Chicago had one when I lived there in the 1960's. Rick N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
The Museum of Science and Industry in Chicago had one when I lived there in the 1960's. You lived at the Museum of Science and Industry? :) Sorry, couldn't resist. But, you actually can live there for a month: http://www.msichicago.org/matm/ Randy. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
There is at least one in DC, at the Smithsonian iirc. RPI, where I went to college, had one in the 3 story stairwell in the library. Don't know if it is still there. I remember one someplace in London too. Someone mentioned temperature compensation. What would you need to compensate for? Temp change in the wire wouldn't effect the rotation as far as I can tell. Swing length might be different based on temp of the wire I guess, but with a long pendulum, I think the magnet is going to way overcome that issue. The one @ RPI had issues due to air movement in the shaft, but that's a different problem. I suppose the right method is to use a GPS disciplined oscillator and the appropriate divider to drive the magnet under the floor. :) To cut down in draft induced drift and jitter, you'd have to put the whole thing in a vacuum though! On Wed, Jul 21, 2010 at 10:13 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: Hal Murray wrote: Several years ago, I found a web site for a commercial place that made them for museums. (I forget why I was looking for that sort of stuff.) You might find interesting stuff/ideas via google but I didn't find a similar site with a bit of searching. The Museum of Science and Industry in Chicago had one when I lived there in the 1960's. Rick N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Well, Morris, this does sound interesting. You've had some pretty conventional replies, so let's up the ante a bit. If you need to know where something macroscopic is in space, attach a GPS receiver to it. Then program some PIC device (lots of advice about that on this list) to compute optimum impulse points after calculating an error that can be corrected by the minimum possible impulse. NASA could advise you about small impulse rocket systems. They may even have a few Space Shuttle micro thrusters and fuel systems for sale. You may be able to drop fuel and oxidizer into the tanks at certain positions of the bob. The bob on a Foucault pendulum is usually quite massive, so there's no reason why it can't be inexpensive lead-acid batteries that are recharged by solar cells. I'm sure you'd save money over mechanisms to move the pivot or huge magnets buried in the floor. Given present unemployment levels, you may be able to hire a person to deliver impulses to the bob as required. But most of the world has automated such systems because people are not reliable. Heck, you could build a pendulum and a metaphor for our times. Best regards, Bill Hawkins (also on Jack's BA list) -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris Odell Sent: Wednesday, July 21, 2010 7:13 PM To: time-nuts@febo.com Subject: [time-nuts] A different timenuts interest Hi all, I have been asked to help with the construction of a Foucault pendulum. This is a long pendulum which oscillates in a slow stately fashion in a fixed plane which appears to move as the earth rotates. In reality the surrounding environment is really moving relative to the plane of oscillation. The pendulum requires a sustaining system to compensate for the inevitable energy loss with each swing. The system is located in the building and therefore rotates relative to the pendulum. It needs to provide an impulse which does not affect the plane of oscillation of the pendulum. I was thinking of an electromagnet located below the centre of the swing which would be pulsed appropriately as the bob passes over it. Has anyone here had any experience with such a system of have any suggestions regarding the sustaining system? This is an interesting and challenging project. Cheers, Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
Silly me, I just realized you need to compensate for the change in length with temperature. This sounds like a great project! On Wed, Jul 21, 2010 at 10:26 PM, Bob Bownes bow...@gmail.com wrote: There is at least one in DC, at the Smithsonian iirc. RPI, where I went to college, had one in the 3 story stairwell in the library. Don't know if it is still there. I remember one someplace in London too. Someone mentioned temperature compensation. What would you need to compensate for? Temp change in the wire wouldn't effect the rotation as far as I can tell. Swing length might be different based on temp of the wire I guess, but with a long pendulum, I think the magnet is going to way overcome that issue. The one @ RPI had issues due to air movement in the shaft, but that's a different problem. I suppose the right method is to use a GPS disciplined oscillator and the appropriate divider to drive the magnet under the floor. :) To cut down in draft induced drift and jitter, you'd have to put the whole thing in a vacuum though! On Wed, Jul 21, 2010 at 10:13 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: Hal Murray wrote: Several years ago, I found a web site for a commercial place that made them for museums. (I forget why I was looking for that sort of stuff.) You might find interesting stuff/ideas via google but I didn't find a similar site with a bit of searching. The Museum of Science and Industry in Chicago had one when I lived there in the 1960's. Rick N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
bow...@gmail.com said: Silly me, I just realized you need to compensate for the change in length with temperature. It depends... If your setup to replace the energy is PLLed to the pendulum position it doesn't need to know the period. (at least not very accurately) -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
I remember one someplace in London too. Science Museum in South Kensington, I'd expect, but I've not been there 20+ years. -John Someone mentioned temperature compensation. What would you need to compensate for? Temp change in the wire wouldn't effect the rotation as far as I can tell. Swing length might be different based on temp of the wire I guess, but with a long pendulum, I think the magnet is going to way overcome that issue. The one @ RPI had issues due to air movement in the shaft, but that's a different problem. I suppose the right method is to use a GPS disciplined oscillator and the appropriate divider to drive the magnet under the floor. :) To cut down in draft induced drift and jitter, you'd have to put the whole thing in a vacuum though! You don't want to drive it from a clock, IMO. You want to make it a free-running oscillator. Period is irrelevant. -John == ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
[snip] The bob on a Foucault pendulum is usually quite massive, so there's no reason why it can't be inexpensive lead-acid batteries that are recharged by solar cells. IMO, there is no reason to put anything active on the bob. I'm sure you'd save money over mechanisms to move the pivot or huge magnets buried in the floor. The pendulum is very high Q. You don't want or need a lot of force. I'd guess a coil smaller than a coffee cup would be more than enough. Given present unemployment levels, you may be able to hire a person to deliver impulses to the bob as required. But most of the world has automated such systems because people are not reliable. True. When in China in about 1979, I was astounded they had Elevator Operators. Many of them, but they had more people than jobs. Heck, you could build a pendulum and a metaphor for our times. Best regards, Bill Hawkins (also on Jack's BA list) Best, -John ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A different timenuts interest
J. Forster wrote: The problem is straight forward, except for sensing the position of the pendulum so the impulse is applied at the correct phase. There must be a bunch of published designs, but if I were to try it, I'd use something optical or capacitive. For optical, I'd put a annular ring of IR LED/Phototransistor assemblies around the center, wired OR the outputs, and use the signal to trigger the impulse. The bottom of the pendulum should be polished or mirrored. The usual scheme is a couple of optical paths at the top of the pendulum with lenses to focus the beam down to a very small diameter (smaller than the wire diameter). The two optical paths are at 90 degrees to each other, and are logically anded either by using a pair of detectors/paths, or by using a mirror to fold the path. It's aligned with the pendulum perfectly stationary (i.e. it's been sitting still for a day or two) so the beam trigger occurs precisely at the center point. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
