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Bulle Bulle shenanigans

Thurmond

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Dec 14, 2021
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Not too sure what the intent of these modifications are but surely will make it more of a challenge to restore it to its original state.

It looks like a transistor was being used to deliver the current pulse, yet the transistor was being controlled via the fork/pin. Maybe this is an attempt to reduce the electrical stress on the fork/pin? The only reason I can think to do this is the use of higher voltage. The coil has been rewound so maybe something is going on there that required higher voltage. I haven't measured the coil resistance yet.

Thurmond

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sophiebear0_0

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Nov 5, 2012
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I suspect you are right in that it is an attempt to convert the Bulle from mechanically switched to transistor-switched.

Interestingly Bulle made and "Electric Bulle Model" that used a second hairspring to bypass the fork contact. I have attached a couple of pictures. I had initially assumed this was a home-made modification - but I have seen serval variations of case design. So I'm pretty confident it is factory produced. I assume the transistor switching circuit was housed within the base in a similar way to the ATO/Kundo's. I am not aware of any official documentation on the Electric Bulle Model.

Your clock however does seem to be a modification of a conventional XA model by "an enthusiast".

Are the fork contacts in sound condition ? I was thinking that a previous repairer may have thought that the conversion to a transistor switched arrangement was easier than trying to repair the fork contacts.

I would be interested to hear more as you delve deeper.

Regards,

Peter

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Thurmond

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Hi Peter,

I haven't seen a factory transistorized Bulle yet. Very interesting and I'm going to keep a look out for one of those.

The fork on the clock at hand, is one of the later plastic ones with the 'S' style contact. It appears to be in good condition.

The coil resistance measured 1550 ohms, and I don't like the looks prior winding - kind of sloppy and missing cloth wrapping.

So I'm going to rewind this one.

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Comparing this XA to very original one that I had laying around, the castings are entirely different:

Clock on hand (movement #263807)
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Early clock (movement #57998)
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sophiebear0_0

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Nov 5, 2012
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Hi

Thanks for the additional photos.

I agree that it looks like the coil has been (badly) rewound. So probably a good idea to start again and do a fresh rewind.

I think the XA movement is standard, and your early one if different ? I do have a couple of XA's but its a bit of a fiddle to remove them from the cases to check. However there is restoration #17457 on the Horologix site which shows an XA movement.

The plastic forks are good in that they do not suffer from shorting issues. However once the silver contact wears down, they are not easy to repair.

I don't have an "Electric Bulle Model" in my collection (yet). I have missed out a couple of times by a singe bid. They don't come up fore sale very often. My guess is that teh transistor is on a pcb in the base, rather than actually embedded within the coil.

I wasn't sure whether your picture shows the movement in its case, or whether that is a test stand ? Does teh model tally with anything in the Bulle catalogues ?

It looks like the hairspring has become unsoldered from the pendulum rod. Have you tried the clock to see whether the transistor circuit actually works ? That said, I think I would want to restore the movement to its original configuration. It shouldn't be too difficult. You will probably need to look very carefully to see where the insulating material is missing.

Best regards,

Peter
 

Thurmond

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Dec 14, 2021
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I agree that it looks like the coil has been (badly) rewound. So probably a good idea to start again and do a fresh rewind.

I wasn't sure whether your picture shows the movement in its case, or whether that is a test stand ? Does teh model tally with anything in the Bulle catalogues ?

It looks like the hairspring has become unsoldered from the pendulum rod. Have you tried the clock to see whether the transistor circuit actually works ? That said, I think I would want to restore the movement to its original configuration. It shouldn't be too difficult. You will probably need to look very carefully to see where the insulating material is missing.
Hi Peter,

I'm starting to wonder if the coil could possibly be original. There are lots of reasons to suspect that its been tampered with. The actual coil wire is protected by a strip of paper that has been taped. And then the paper was covered using thread, wound about 1000 times. I've never seen a coil covered by thread. But the paper layer looks really old. The tape has yellowed as old tape tends to do.

The movement is in my test stand. The case shown below.

I thought it would be interesting to try running the clock as is yesterday (a bit too late now), but I didn't want to get into re-soldering that wire to pendulum rod. I think the clock was trying to tell me "get this weird stuff off of me and put me back together the way I'm meant to be."

Thurmond

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sophiebear0_0

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Nov 5, 2012
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Thurmond

Thanks for the photos. Its going to make a nice looking clock.

You normally only find the cord wrapping on the larger coil found on the Talle A type movement. This starts life as a pale green, but tends to age to a straw colour. If you unwind old cord wrap it tends to look a little spiral-like with the colour changes.

The small coils are normally covered with either a black painted brass shroud, or in a green cotton ribbon (as per your other XA model). The black brass shroud is normally used when the coil is actually visible. In cases where the movement is hidden from view, the green cloth ribbon is most common.

Your cord looks to be plain white. The resistance (1550 ohms) seems a little high to be original. Also the paper wrap would have to have been removed to allow the 2 pairs of lead wires to be attached. The paper wrap may possibly be original of course. I wonder whether there are any markings on the transistor/capacitor/resistor that could help date the modifications.

I don't think a coil resistance of 1550 Ohms will present a problem and I would expect the clock will still run on 1.5 volts. One simple check is to rove teh movement and connect the power directly to the coil. Then manually touch and un-touch the battery to see whether the coil/magnet combination runs off 1.5 volts. There is a short video clip on the Horologix site that shows this method.

Best regards,

Peter
 

praezis

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Feb 11, 2008
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I can see four wire ends. Does it mean, you have two independant coils?

Frank
 

Thurmond

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I can see four wire ends. Does it mean, you have two independant coils?

Frank
Hi Frank,

The four wires are part of the secrets of this clock. Originally, two of the leads had be tied together (see below). I separated them when I was removing the outer thread yesterday. I can only speculate that the prior person realized that they hadn't enough resistance after the initial winding, and then added more turns.

I plan to unwind the actual wire today and see what's really going on in there.

Thurmond


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Chris Radek

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Apr 13, 2014
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These could be two separate windings on purpose, a sense and drive coil. If I was eliminating the contact system in favor of a transistor, that's what I'd do, copying the Accutron circuit. The Seiko Sonola does the same thing, except there are two bobbins instead of one.

(this is not my site)

(this however is my drafting skills)
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Thurmond

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Dec 14, 2021
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That was my thought, too. Also Ato used a similar circuit (and Kundo and ...).

Frank
I think you guys are right about the electrical strategy applied to this Bulle.

I started dismantling the coil to rewind it, and found an outer band of wiring, and a inner band of wiring. The pixs below show coil after the outer wiring has been removed. And I'm about to remove the inner wiring.

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sophiebear0_0

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Nov 5, 2012
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Thurmond

Thanks for posting the pictures.

I guess you aren't planning on reusing the original coil wire :)

I note that the coil former looks to be plastic ? This had me wondering whether the previous restorer had actually made use of an original ATO/Kundo/Junghans coil, rather than modified the original Bulle coil ? I seem to remember that Bulle used wooden coil formers - but I can't be 100% certain. This would explain why you thought the coil looked old & original. If the coil did come from a ATO/Kundo/Junghans - then it would probably have been housed in thin brass shroud. This might explain the later addition of the white cord wrapping. And of course would explain the modified electrical circuit.

Regards,

Peter
 

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