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Thread: The SMITHS QUASAR "Constellation"

  1. #101
    Master Mr Curta's Avatar
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    Quote Originally Posted by tokdok View Post
    Ollie Don't worry too much about losing the screw, I have plenty..
    If you loosen either screw slightly & take out the other, slip the cell under the contact clamp (pointy end/positive of the cell down) & then you
    will need to press the loose bridge/contact arm over with a toothpick or similar to align the holes, & then insert the screw (you will need tweezers to place it in position before screwing down) Hopefully it will then start ticking.. any problem let me know..
    john
    What could possibly go wrong?

    Some plastic sheeting might be a good idea Rev. Speaking from experience...

  2. #102
    Craftsman
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    ....and a magnet (somewhere not to nearby) for finding the blighter....

  3. #103
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    No thanks needed

    Quote Originally Posted by M4tt View Post
    First, tokdoc, cheers, pm sent...

    Second. As I'm finally not seeing spots in front of my pain for the first time in days, I celebrated by doing maths. I'm not good at maths, but I think I've found an elegant solution by the simple expedient of dividing back from 1,548,288 - 7 is the highest unique division before ten and so makes a decent sized division without being too physically large or power draining for the tech of the time.

    It makes sense to do the largest division first as it means that all the other circuits are charging and discharging at a much slower rate, clawing back the power spent on this first division.

    This gives 221184. Dividing this by 2,3,5 and 7 gives nothing exciting, so divide by 3 then 2,3,5 and 7 again, nothing particularly divisible and so divide by 3 again and bingo: 8192: it's division by two all the way to .5. I bet there's a prettier way of getting this, but I'm no good at maths. I'm not going to admit how many discrete calculations I've done today, but I reckon that, unless they are using a circuit that divides by more than ten, which I confidently don't expect, then this is how they did it.

    I also worked out that there must be four coils, which tokdoc has confirmed, and that it will therefore move by a quarter turn, as his fine new video confirms, so that's four coils wired in series and something like a square wave pulse so that .5 gives a 1hz movement. That explains the capacitor, which must also be in series. It's amazing how it all falls into place!
    No thanks needed, Im very glad I could help..
    John

  4. #104
    Quote Originally Posted by tokdok View Post
    Ollie Don't worry too much about losing the screw, I have plenty..
    If you loosen either screw slightly & take out the other, slip the cell under the contact clamp (pointy end/positive of the cell down) & then you
    will need to press the loose bridge/contact arm over with a toothpick or similar to align the holes, & then insert the screw (you will need tweezers to place it in position before screwing down) Hopefully it will then start ticking.. any problem let me know..
    john
    Umm, yeah, about that.

    Are they special screws, unique to the Quasar?

    Suppose someone had lost one . . . I mean, hypothetically.

  5. #105
    Quote Originally Posted by Mr Curta View Post
    What could possibly go wrong?

    Some plastic sheeting might be a good idea Rev. Speaking from experience...
    Quote Originally Posted by size11s View Post
    ....and a magnet (somewhere not to nearby) for finding the blighter....
    It flew like a bird from the tweezers' mandibles and pinged twice on the hard floor.

    A sweep with a strong magnet failed to produce anything.

    so . . . . I have reached out to the Mighty John for help.

    I'm hoping they're not special screws, unique to the Quasar, and that general ones will fit.

    I have managed to bodge the job by tightening the other screw and then simply putting the back on, although whether the terminal is now touching the inside of the case back I do not know. It is ticking away though!

  6. #106
    Master
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    Quote Originally Posted by Rev-O View Post
    It flew like a bird from the tweezers' mandibles and pinged twice on the hard floor.

    A sweep with a strong magnet failed to produce anything.

    so . . . . I have reached out to the Mighty John for help.

    I'm hoping they're not special screws, unique to the Quasar, and that general ones will fit.

    I have managed to bodge the job by tightening the other screw and then simply putting the back on, although whether the terminal is now touching the inside of the case back I do not know. It is ticking away though!
    This has happened to me so many times that I now don't even bother. I've found that using a little bit of blutac to hold anything small enough to ping is perfect for orienting and setting up before screwing.

  7. #107
    Apprentice OhDark30's Avatar
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    Thanks to all posters (and Matt for linking to this thread)
    Bloody fascinating to a tech minded Smiths fan who grew up down the road
    Thanks for all the patient cataloguing, recording, surmising and piecing together

  8. #108
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    Ok, I think I can tell a consistent tale from start to finish. I'm not promising that it is correct in all the details, but it fits what we know so far.

    I like poetry. One of the reasons I like it so much is that it is so constrained. There are arcane rules of rhythm and meter and so on. A good poem works around and through all the constraints on it to leave you with something that feels like changing anything would be a step away from perfection and the words on the page are all that they could ever have been.

    I've said it many times before, but every watch is a compromise and, to a certain degree, like poetry, it is how well that a watch movement manages the compromises and constraints of being a watch that is the measure of its greatness.

    The Smiths Quasar really has its work cut out. Not only does it have the usual constraints of the size of the case, but it also has another constraint: the size of the integrated circuit in 1974. The reason that early quartz went for low frequencies like 8190 is simple - they literally didn't have room for enough transistors to divide a larger number. By '74 the situation was improving, but not by much.

    As if that isn't enough, the power of the battery also severely restricts how many transistors (and how rapidly they charge and discharge) the watch can have and also the ways that electrical energy can be converted to mechanical energy. So the other reason the very first quartz went for low frequencies was to save power. Smiths made a tactical decision to go the other way.

    In base two, there probably isn't enough power to step down from a high frequency lenticular quartz without draining the battery too fast, even if there was enough space on the available integrated circuit. What is certain is that Smiths chose not to have a quartz that resonated in a multiple of two. However, had they wanted to they could have had 1,048,576 or 2,097,152. Omega in their ship's marine chronometer, rather than their wrist one, opted for the simple but large and comparatively power hungry 4,194,304hz. I'm not doing the maths for their 2,359,356hz wrist chronometer! E

    But I have for the Smiths: I think Smiths solved the problem by starting with as large a division as was practically possible. There are only four prime numbers below eleven - 2,3,5 and 7 and, for a variety of practical reasons, it's almost certain these are the numbers Smiths would have worked with.

    So here's my idea of how the Quasar works.

    When a battery is first inserted and the crown pushed in, an oscillator circuit on the integrated circuit will begin to, well, oscillate. This sends a fairly unstable and harmonic oscillating signal down one of the six 'legs' of the integrated circuit to one one of the two 'legs' attached to the quartz crystal. This will cause the quartz to vibrate. As the quartz is either a tuning fork:

    https://www.youtube.com/watch?v=lxsM9Jv0OD8

    or a disk not unlike a tingsha:

    https://www.youtube.com/watch?time_c...ature=emb_logo

    That is tuned to a pure note, then, as long as the signal is applied to the quartz it will chime, at a very high, pure, frequency, just as a tuning fork or tingsha would.

    However, the quartz doesn't just give off sound (which we can't hear) it also releases an electric current as it vibrates. This pure oscillation returns to the integrated circuit (IC) down the other leg attached to the quartz crystal and up another of the six legs on the IC. This signal then goes to the divider circuit.

    The signal oscillating at 1,548,288hz is then divided by 7 by the first dividing circuit giving 221,184.

    This is divided by three by the next circuit giving 73,728

    This is divided by three by the next circuit giving 24,576

    This is divided by three by the next circuit giving 8,192

    This is divided by two by the next circuit giving 4,096
    This is divided by two by the next circuit giving 2,048
    This is divided by two by the next circuit giving 1,024
    This is divided by two by the next circuit giving 512
    This is divided by two by the next circuit giving 256
    This is divided by two by the next circuit giving 128
    This is divided by two by the next circuit giving 64
    This is divided by two by the next circuit giving 32
    This is divided by two by the next circuit giving 16
    This is divided by two by the next circuit giving 8
    This is divided by two by the next circuit giving 4
    This is divided by two by the next circuit giving 2
    This is divided by two by the next circuit giving 1
    This is divided by two by the next circuit giving .5

    This signal goes through a final inverter circuit and a capacitor and powers the motor windings. There's nothing fancy, just four motor windings all connected together in series. With a square shaped sine wave, the motor moves on the 'tick' and stops on the 'tock', moving the motor by a quarter of a turn every second. This will then be geared up by X4 by the gear train to give a 1 hz tick and geared down by /60 and /60 for the minute and hour hands.

    I think that catches it all, but I doubt it's perfect as I'm not an expert and I'm cobbling together bits and bobs from all over, for example, thanks is due to my almost childhood D1 BSA Bantam rectification circuit for helping me fumble my way through the inverter while ensuring that my toolkit still has a pack of blue Rizla in it! However, if my error shakes a real expert out of the woodwork then I'll be delighted


    Any comments?
    Last edited by M4tt; 18th February 2020 at 08:28.

  9. #109
    Apprentice OhDark30's Avatar
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    The SMITHS QUASAR "Constellation"

    Re: earlier thoughts about male researchers taking undue credit, there’s the nearer to home example of Jocelyn Bell Burnell and the discovery of the quasar itself https://medium.com/s/the-matilda-eff...t-5362bef36308
    Last edited by OhDark30; 16th February 2020 at 11:41.

  10. #110
    Master
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    And just for the fun of it: the Omega 2.4:

    2,359,296 /3
    786,432 /2
    393,216/2
    196608/2
    98304/2
    49152/2
    24576/2
    12288/2
    6144/2
    3072/2
    1536/2
    768/2
    384/2
    192/2
    96/2
    48/2
    24/2
    12/2
    6/2
    3/3
    1

    It was worth doing the maths, but only because I hit on the 3 into 2 series almost immediately and the 3 at the end was obvious. I was kind of hoping that it was also a 7 division to start with...

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