I understand, though I was thinking a small coil could be placed inside the case near the balance wheel. Worst case it seems fully reversible (depending on mounting the coil and a small hole for the wires to come out) and worth a try.
On Sat, Feb 1, 2020 at 10:31 PM Bob kb8tq <[email protected]> wrote: > > Hi > > Keep in mind that these particular chronometers were designed (as best as > was possible) to be impervious to outside influences. Mag fields, rocking back > and forth, orientation changes all should have whatever the lowest impact you > could make them have. > > Bob > > > On Feb 1, 2020, at 9:58 PM, Ben Bradley <[email protected]> wrote: > > > > I'm wondering about the balance wheel, if it's ferromagnetic (has iron > > or steel in it, which would probably make this idea not work), or if > > it's perhaps all aluminum or similar non-magnetic material. Adding a > > constant magnetic field from a coil and electric current source would > > provide a magnetic induction-induced drag on the balance wheel and > > slow it down (hopefully not so much that it stops). Setting the > > chronometer to normally run slightly fast would allow it to be slowed > > down and regulated by the strength of the magnetic field on the > > balance wheel. > > > > On Sat, Feb 1, 2020 at 3:06 PM Bob kb8tq <[email protected]> wrote: > >> > >> Hi > >> > >> If the idea is to generate a rate card and keep it up to date ….. I think > >> that > >> can be done with just the GPS. The CSAC really does not add a lot that > >> I can see to that case. > >> > >> Of course I may have (yet again) missed something …. > >> > >> ====== > >> > >> The very standard / “old school” approach for this is a microphone on the > >> case > >> of the M21. These days feed the mic preamp output into a cheap micro along > >> with the GPS info and away you go. Spit the results out to a little OLED > >> display > >> maybe ….. > >> > >> Bob > >> > >>> On Feb 1, 2020, at 1:39 PM, Tom Bales <[email protected]> wrote: > >>> > >>>> > >>>> Many thanks for everyone's response on my cesium-synchronized mechanical > >>>> chronometer project. I'll keep the group informed of progress. Some > >>>> responses to your questions and suggestions: > >>> > >>> > >>> - My current plan is to use a chronometer that has been adjusted for > >>> rate and is close to dead-on. Of course, they're never dead-on, and > >>> that's > >>> why keeping track of the rate is important. I haven't dismissed the idea > >>> of actually disciplining the chrono from the CSAC, but since this > >>> chrono's > >>> rate adjustment involves screws on the balance wheel (it has a > >>> free-sprung > >>> helical balance spring without any means of adjustment), that would be a > >>> great challenge. Perhaps the best would be for the CSAC system to > >>> maintain > >>> a "rate card" of the chronometer, so that when all the electronics fail, > >>> and the user is left with only the chrono, at least they would have a > >>> really good knowledge of its rate and variation. Doing so would require > >>> a > >>> feedback signal from the chrono, which could be acoustic or > >>> photoelectric. > >>> The electronic rate card could be updated now and then by turning off the > >>> sync impulse to the chrono and listening for the ticks to move relative > >>> to > >>> the 1pps. > >>> - The chrono would need a bigger box in order to incorporate the > >>> CSAC/GPS system, microcontroller, and--the biggest part--backup > >>> batteries. > >>> That's part of the fun, and I'm thinking to mount the gimballed chrono > >>> in a > >>> purpose-built enclosure that will hold everything. Connections to the > >>> chrono will have to be very flexible FFC or silicone wire. > >>> - I thiink auto-winding is a definite requirement. The engineering > >>> challenge is to couple a small gearmotor to the winding system without > >>> disabling the manual-winding system that uses a ratcheted key. Winding > >>> noise should be short in duration, so it probably won't affect the time > >>> sync. People have wound chronos by turning them upside down in the > >>> gimbals > >>> and poking a key through a hole for a long time without any big issues. > >>> - Coupling to the chrono balance and escapement might be difficult, or > >>> it might be easy. If it takes hours or days to synchronize, that's OK, I > >>> think. My guess is that anything that generates a slight impulse in the > >>> direction of the escapement detent or a torque pulse to couple to the > >>> balance will work well enough--a tiny little linear or rotary > >>> electromagnetic actuator should work. We'll see. > >>> - The Hamilton M21 chrono beats at 2Hz, so driving it with a 1pps signal > >>> will probably work fine. > >>> - The idea that TVB suggests of disciplining the CSAC to match the > >>> chrono is fascinating, indeed. Hadn't thought of that one. It would be > >>> the easiest way to keep the chrono and CSAC in sync, and it would still > >>> use > >>> the traditional rate-card method of keeping track of the actual time. > >>> Hmmmm. > >>> - Yes, the CSAC modules are expensive! Over $5k currently. It seems > >>> like during the evaluation period the company sold them "at a discount" > >>> in > >>> order to build applications and sales (or so the court documents say). > >>> Let > >>> me know if anyone sees a gyneesium one on *bay. I thought long and hard > >>> before buying it, but idle hands are the devil's cash register. (Oh, > >>> oh!--now I have an excuse to buy an HP 53230!) In my initial > >>> measurements > >>> of rate (after GPS disciplining for 24 hours) the CSAC freewheels within > >>> 1.7ms/yr. Probably good enough. Needs longer testing. > >>> - The M21 has a single balance wheel consisting of an Invar spoke and a > >>> stainless steel ring (it was Hamilton's magical way of doing temperature > >>> compensation to match the balance spring. The Russian knock-offs have a > >>> standard bi-metal split balance wheel. The Hamiltons beat just about > >>> anything in performance. Besides, "Murica!". > >>> _______________________________________________ > >>> time-nuts mailing list -- [email protected] > >>> To unsubscribe, go to > >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >>> and follow the instructions there. > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > >> and follow the instructions there. > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
