Bulle Post Your Bulle-Clocks Here

Discussion in 'Electric Horology' started by John Hubby, May 7, 2002.

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  1. sophiebear0_0

    sophiebear0_0 Registered User

    Nov 5, 2012
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    Interesting observation about the impact of battery type on electromagnetic clock regulation.

    I think there are 2 possibilities here:

    1) The under load voltage supplied by the C & D batteries were slightly different. I have often observed that as the battery drains, the amplitude will reduce and the clock will run fast. Note that the model in question does not have an iso-spring to compensate for the change in battery voltage. The clock has the later cobalt magnet that is prone to lose its strength over time.

    2) Steel cased batteries may impact the magnetic field and hence impact time regulation. My personal experience is that I have seen it with the small 1/4 second ATO movements where the battery sits very close to the magnet coil. I once made up a battery holder using a steel box and it played havoc with the regulation ! Of course the ATO magnet is a simple N-S magnet, rather than the S-N-S that you find in most Bulles. That said, the cobalt magnet for the clock in question will probably be a N-S magnet. I say "probably" because sometime 2 separate magnets are fitted, creating a N-S-N field.

    With the Bulle clock in question, the coil/magnet assembly is quite high on the pendulum rod. So there is quite a distance from the coil/magnet to the battery which is housed in the base. So I would have thought any impact on battery casing would be a lot less than in the case of ATO clocks Personally I would look closer at Point (1) as a possible explanation, but I'm not sure I could totally rule out Point (2) if the battery voltages under load were identical.

    It interesting to note that some of the 1/4 second ATO clocks actually has a small magnets mounted on the case, directly behind the main magnet. This was supposed to allow the user to fine tune the regulation.

    Apologies for the over-long and meandering response. Hope it makes sense ?

    Regards,

    Peter
     
  2. praezis

    praezis Registered User

    Feb 11, 2008
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    Peter,
    my bigger (1/2-s) ATO clock has magnetic fine tuning, too:

    Ato_magn.jpg

    Frank
     
  3. sophiebear0_0

    sophiebear0_0 Registered User

    Nov 5, 2012
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    Good point Frank. I have a couple of 1/2 second models that have something similar. And of course the Brillie type clocks also have a small magnet mounted about the coil.

    The reason why I highlighted the 1/4 second ATO clock is the battery will normally sit between the primary magnet and the small magnet at the back of the case. So it is easy to envisage that this will impact the effectiveness of the fine-tuning magnet. This secondary magnet is not fitted to all 1/4 second movements. I must confess i always try and regulate my ATO's with the rating nut and leave the secondary magnet in the "neutral position". I also try and mount the battery as far away from the magnet where possible - or in a vertical plane and mid-magnet when space does not permit. The approach seems to work ok.

    Regards,

    Peter
     
  4. focusrsh_b07732

    focusrsh_b07732 Registered User
    NAWCC Member

    Dec 17, 2009
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    The electrical engineer in me has major doubts about the whole D vs C-cell comparison. I don't like guesses.
    The Bulle I am restoring won't be done for another month or so (waiting on some materials) but when it is, I'll put an oscilloscope with voltage and current probes on it and measure what it does with different batteries. That should be interesting and fun. I'll report the tests here.
    - Carl
     
  5. Simon Holt

    Simon Holt Registered User
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    Mar 21, 2017
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    Good afternoon, all.

    I've been working on clocks as a hobby now for about four years. I've never worked on an electro-magnetic movement before, but I've been asked to take a look at this non-running Bulle clock. I've read all 600+ posts in this thread, and learned a great deal – thank you all for your contributions. But after an initial inspection of the clock I do have some questions that I hope someone can help me with.

    First things first: the clock is serial number 54039 (which I gather is from 1926, although John Hubby's table is no longer available on the BHI web site):
    2020-05-19 10.18.30.jpg
    The clock has been in the owner's family for many years and he reports that he does not know of any work being done on it. He last saw it running about a year ago, so I'm hopeful that nothing is missing and that all I'm chasing is poor electrical conductivity.

    Rocking the pendulum manually advances the crown wheel as expected. A meter across the coil shows 1200 ohms, so that's OK. The contact spring had fallen off the fork arbor. I've put that back on but it doesn't look original – it looks longer than the replacements I've seen on sale:
    2020-05-20 17.50.16.jpg
    Is that a cause for concern?

    My second question regards the fork. I was getting very poor conductivity there until I applied some switch cleaner. It appears to be worn asymmetrically; this frontal view shows significantly more of the riveted-on material on one side than on the other:
    2020-05-21 12.22.27.jpg
    Again – is that a cause for concern? Supplementary question: what is that material? It looks like it should be an insulator, but if I've understood the principles of operation correctly it must be conductive.

    Incidentally, the work I've done so far (re-connect the contact spring & spray switch cleaner on the fork) hasn't made it want to run. I'm waiting for some additional leads for my multi-meter so I can check the basic functionality of the coil, curved magnetic bar and pendulum but in the meantime I'd like to know if I'm likely to need any new parts.

    Simon
     
  6. focusrsh_b07732

    focusrsh_b07732 Registered User
    NAWCC Member

    Dec 17, 2009
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    Does anyone know the gear-train values for an early Bulle? I've searched this entire thread but don't find anything.
    What I'm looking for is the # of teeth on the crown wheel, the worm & pinion ratio, etc.
    I want this so I can accurately set the rate of the clock without taking hours to sneak up on it. If I know the gear ratios, then it is simple to calculate the correct pendulum period and use electronics from there to measure and adjust it.
     
  7. praezis

    praezis Registered User

    Feb 11, 2008
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    A Clockette has 10080 bph.

    Frank
     
  8. focusrsh_b07732

    focusrsh_b07732 Registered User
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    Dec 17, 2009
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    Hi Frank,
    Thanks! But I should have specified that I have an early model, like pictured here, and not a Clockette. It beats much slower.
    - Carl

    Bulle, front, 1.JPG
     
  9. focusrsh_b07732

    focusrsh_b07732 Registered User
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    Dec 17, 2009
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    I finished Bulle #12520, circa 1921. It is happily keeping excellent time.

    Bulle #12520.JPG Bulle #12520 without dial.JPG
     
  10. focusrsh_b07732

    focusrsh_b07732 Registered User
    NAWCC Member

    Dec 17, 2009
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    I designed and built a precision DC-DC boost converter for the above clock. It generates a very stable 1.5V from a 8000mAhr NiMh rechargeable battery. The battery and converter fit nicely in the clock where the original 1.5V dry cell would have been. (It's attached with double sided tape.) The converter's quiescent draw is 19.4uA. In other words, during the pendulum period when the fork-toggle is not powering the coil, that is how much current it draws. My measurements and calculations suggest the clock will run well over a year on a single charge. (663 days, actually.) Since the battery is guaranteed to take over 500 charge cycles, well, we'll all be dead for many generations before it needs to be replaced.;)

    I was thinking about doing V2.0 of the regulator if enough people are interested. It would have a precision trimmer so you could adjust the voltage from about 1.4V to 3.5. It also would have precision current sense resistors in case you want to measure the current on both battery and clock sides. With the battery, holder, regulator etc. it would be about $50. You can contact me with a private message if interested.

    - Carl Dreher

    regulator close-up.JPG regulator in clock.JPG
     
  11. praezis

    praezis Registered User

    Feb 11, 2008
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    Hello Carl,

    what beat rate did you find in the end?

    Frank
     
  12. focusrsh_b07732

    focusrsh_b07732 Registered User
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    Dec 17, 2009
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    With the clock adjusted fairly well, I record a 884mS period, which is about 4072 beats/hr.
     
  13. PowerClocks

    PowerClocks Registered User
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    Apr 3, 2004
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    Hi Peter, I recently bought a clock with a very similar movement, I have been told by the seller there may be parts missing and that he was unfamiliar with this model of clockette, I think he also thought it was not a Bulle but a clock made under licence, The one I have bought also says Bulle on the dial but since I do not have it yet I can not supply much information except pictures that described it on FleaBay, could you write to me on powerclocks@hotmail.com so I can swap information, my restoration could be easy, it could be a chore but it will get done with a bit of help, If I know what is missing, usually I either make the parts or buy them but good pictures are key to a good, undetectable job.

    Graeme Power

    Clockette 002.jpg
     
  14. focusrsh_b07732

    focusrsh_b07732 Registered User
    NAWCC Member

    Dec 17, 2009
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    I finished V2 of a regulator for Bulle, ATO and other low-voltage, low duty-cycle clock. It is 3.6cm wide x 3.5cm deep x 8.2cm tall. (~ 1.4" x 1.4" x 3.2".) This hides perfectly in the battery compartment of my 1921 clock.
    Output is guaranteed adjustable from 1.4V to 4.5V. Uses a 1.2V Ni-MH 8000mA-hr rechargeable battery. This should power a Bulle for at least a year, but that obviously depends on where the output voltage is set, the adjustment of the contact fork on the pendulum, magnet resistance, etc.
    If interested in one, please contact me via the forum Private Message.

    - Carl Dreher

    IMG_7232.JPG IMG_7231.JPG
     

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