Longines 41 VHP GMT L287.2 movt photo. - Page 3
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  1. #21
    Member Rhodocene's Avatar
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    Re: Longines 41 VHP GMT L287.2 movt photo.

    Quote Originally Posted by Chasy View Post
    That's what I thought. Almost: one thing is a bit unclear, the Lavet stepper is commonly described as a unidirectional motor.

    But on my Citizen and Oceanus quartz watches hands can rotate both ways.

    Did manufacturers figure out how to drive Lavet backwards by arranging clever pulse sequences?
    Are they using a modified Lavet?
    Yes the standard Lavet is actually unidirectional by design, I don't actually know what kind of magic Longines and Casio use to rotate in the opposite direction. Also see below (DaveM)

    Quote Originally Posted by GMT-man View Post
    Then you should look for those watches which have more jewels than bearing points. They are usually also reasonably cheap.

    Like explained already, "dumb" quartz watches need jewels, while "smart" quartz watches like V.H.P. do not, because there is no gear train in them. Apple Watch also does not have jewels, your smart phone does not either, even though it also shows time.
    I would like to use this rare opportunity to ignite a flame-war: The Rolex 3135 has at least two jewels next to the date ring that have absolutely no purpose whatsoever

    Quote Originally Posted by DaveM View Post
    The motors are :-Seconds, Minutes and hours (geared together), Date and GMT
    I believe that all of the hands are geared to the motors because they are 'large-angle' steppers.
    Direct-drive small-angle steppers would be perfect, but I think that they would cost too much and be too big.
    I guess that ETA have done a lot of work on these motors, they are very small and (unlike standard Lavet motors) reversible.
    See above (Chasy), also, I read somewhere on Longines' website that the motors used are actually 400Hz stepper motors, so that the hands can be readjusted to hit the indices exactly after a shock, or strong magnetic field (I actually tested the latter with a neodymium magnet, the watch stopped completely, and after removing the magnet the hands realigned perfectly , kind of cool to see)
    And yes, the minutes and hours are driven by a single motor, I stand corrected in my previous post.

  2. #22
    Member dicioccio's Avatar
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    Re: Longines 41 VHP GMT L287.2 movt photo.

    About the number of jewels involved in a movement, a lot has already been said but generally it is not an indicator of the quality of a movement. In fact quartz watches have very low torque on their gears so also a plastic gear (which has a very low friction) could be a great choice.

    About the stepper motors, Casio is using bidirectional movements since more than 5 years so they are not so "recent". The "drive-by-wire" movements are here since at least 10 years and some of them have even each hand individually driven (as my OCW-S100). Also this is not an indicator of the "quality" of the movement (GS 9F and the Citizens have single motor for the 3 hands which are geared together).
    ronalddheld likes this.

  3. #23
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    Re: Longines 41 VHP GMT L287.2 movt photo.

    Bidirectional is not recent. The question is how do they make Lavet move backwards.

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  5. #24
    Member dicioccio's Avatar
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    Re: Longines 41 VHP GMT L287.2 movt photo.

    Quote Originally Posted by Chasy View Post
    Bidirectional is not recent. The question is how do they make Lavet move backwards.
    Maybe it is not a Lavet ^_^
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  6. #25
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    Re: Longines 41 VHP GMT L287.2 movt photo.

    It looks like Lavet. A single coli and an asymmetric stator with a bipolar rotor.

  7. #26
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    One month now. According to time.is, I can't see with my naked eyes any gain or lose of time, not even half second. I do wear it regularly. Great accuracy!!

  8. #27
    Member Rhodocene's Avatar
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    Re: Longines 41 VHP GMT L287.2 movt photo.

    Quote Originally Posted by Huchiz View Post
    One month now. According to time.is, I can't see with my naked eyes any gain or lose of time, not even half second. I do wear it regularly. Great accuracy!!
    I'm at around +1 sec since DST change. That's around +4 SPY. Totally pleased.
    Seiko 5 - SNKK93, Seiko 5 - SNXL45, Orient Kano - RA-AA0009L19A, Casio - MTP-1200A-1AVEF, Casio - EFS-S510D-2AVUEF, Vostok Amphibia - 060640, Pobeda - N/A, Orex - N/A, Skagen Holst - SKW6220, Timex T-series Chronograph - T2M469, Timex 1440 - TI5F681, Tissot PRC 200 Chronograph - T17151632, Certina DS Podium - C001.407.11.037.00, Longines Conquest V.H.P. 41mm - L3.716.4.56.6

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