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Thread: CYGN-B

  1. #81
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    This has been an absolutely awesome thread to read thru. Thank you folks for sharing!

  2. #82
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    Hi DZ. I'm looking for an opportunity to obtain any piece of vintage planetarium equipment that I could use to project a decent looking star field. I have read that the Zeiss models used metal foil with tiny holes of varying sizes meticulously punched through, and colored glass to account for color variations in the stars.

    In case you have anything you might consider trading for my analog Magic Mountain console discussed earlier in this thread, and / or selling outright, you are welcome to contact me.
    Attached Thumbnails Attached Thumbnails Zeiss_Toronto_1982.jpg  


  3. #83
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    I remember the fixed cycloid select knob, and that one of the settings was the KQO. I didn't know there was a different spiral generator that was not the KQO. My memory of the system is mostly before the installation of the AOM. Is it possible the "real" spiral generator was added to the system later? I remember how the AOM changed the appearance of "The Conversation" number in Starship. Ron, you mentioned a "ringing" KQO. Does this suggest the actual KQO used an LC tank circuit similar to the one I built? The most subtle use of the KQO I remember was the Bolero number in Crystal Odyssey, where the swept, symmetry collapsed spirals seemed to slowly unwind themselves.

    I remember that the fixed cycloids could not be accessed unless the data was present (tape rolling), but that if the tape was stopped when the KQO was up, then that image would persist, but slowly decrease in gain. I seem to remember an effect that was a swept spiral with one of the fixed cycloids present at the small part of the spiral once per sweep. I think one time the fixed cycloid selector had not been preset properly, and it was necessary to step through the ROM image of the car to get to the correct fixed cycloid. The audience responded positively to the incongruity of the car briefly appearing.

  4. #84
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    Mar 2010
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    Ron, yeah that was a great kit. Required multiple power supplies. One of the 3 inductances was something like 5 Henrys! The book on the history and theory of formant synthesis was possibly the best part.

  5. #85
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    Feb 2015
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    Default Star Ball

    Quote Originally Posted by Greg View Post
    Hi DZ. I'm looking for an opportunity to obtain any piece of vintage planetarium equipment that I could use to project a decent looking star field. I have read that the Zeiss models used metal foil with tiny holes of varying sizes meticulously punched through, and colored glass to account for color variations in the stars.

    In case you have anything you might consider trading for my analog Magic Mountain console discussed earlier in this thread, and / or selling outright, you are welcome to contact me.
    Greg,

    You might look for an old Spitz star ball. There must be some of those around. Spitz sold many many A3 and A3P projectors and many (most?) of those have been replaced with more modern equipment. The more modern version I used at San Francisco State University (a Spitz 512) was installed 47 years ago - and is still running! There must be some of the older star balls laying around. You could easily replace the arc lamp with a bright LED and probably get a better sky than the original!

    Ron

  6. #86
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    Default Spirals

    Quote Originally Posted by Greg View Post
    I remember the fixed cycloid select knob, and that one of the settings was the KQO. I didn't know there was a different spiral generator that was not the KQO. My memory of the system is mostly before the installation of the AOM. Is it possible the "real" spiral generator was added to the system later? I remember how the AOM changed the appearance of "The Conversation" number in Starship. Ron, you mentioned a "ringing" KQO. Does this suggest the actual KQO used an LC tank circuit similar to the one I built? The most subtle use of the KQO I remember was the Bolero number in Crystal Odyssey, where the swept, symmetry collapsed spirals seemed to slowly unwind themselves.

    I remember that the fixed cycloids could not be accessed unless the data was present (tape rolling), but that if the tape was stopped when the KQO was up, then that image would persist, but slowly decrease in gain. I seem to remember an effect that was a swept spiral with one of the fixed cycloids present at the small part of the spiral once per sweep. I think one time the fixed cycloid selector had not been preset properly, and it was necessary to step through the ROM image of the car to get to the correct fixed cycloid. The audience responded positively to the incongruity of the car briefly appearing.
    Greg,

    The spiral card only was really a fancy VCA. You fed in signals from cycloids (or elsewhere) and it would change the size in a ramped fashion. You could adjust the spiral-IN and spiral-OUT rates (varying the waveform controlling the VCA from a sawtooth to a triangle to the opposite sawtooth. It would also allow the spiral to be swept along an axis so that circular spiral (I'm using a circle to simplify things here...) would be swept out into a cone. (See example below of swept spirals.) The card did several other things (one or the other side of the ramp signal could provide blanking, and the PDM signal originated here too), but you get the general idea.

    Ron
    Attached Thumbnails Attached Thumbnails Swept Spirals.jpg  


  7. #87
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    Way back when Charlie McDanald built a star projector for flat screen shows out of an arc lamp, condenser lens, a huge circular "star plate" that could be spun on its axis and moved in another axis so the rotation axis wasn't in the center of the screen (or on screen at all.), and a projection lens. It was quite a beast.

    Zeiss uses a laser to "drill" their star plates today, then they hand position optical fibers to illuminate just the star apertures.
    Last edited by laserist; 09-24-2019 at 04:46.
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

  8. #88
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    Click image for larger version. 

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    Laser Images filed a design patent way back when - the image above is from that patent. Laser Images' basic framework really didn't change much from their first production console to their last. Yes, some things were added, but they were slotted into the existing framework. So spirals, inverse spirals, diamond spirals, and swept spirals all date back to the beginning. KQO was an addition to fixed cycloids that was introduced with the Mark 6. So was the PDM effect Ron mentioned.
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

  9. #89
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    Default Charlie's projector

    Quote Originally Posted by laserist View Post
    Way back when Charlie McDanald built a star projector for flat screen shows out of an arc lamp, condenser lens, a huge circular "star plate" that could be spun on its axis and moved in another axis so the rotation axis wasn't in the center of the screen (or on screen at all.), and a projection lens. It was quite a beast.

    Zeiss uses a laser to "drill" their star plates today, then they hand position optical fibers to illuminate just the star apertures.
    That projector was a complete full-sized 19" electronics rack. Beast indeed. We used it at the short-lived San Francisco Lone Mountain location. Charlie loved that projector...

    Ron

  10. #90
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    I'm pretty sure I had his star projector in Chicago at the Park West in 1980. Certainly that's when I really got to know Charlie. I recall that running a Mark 6, star projector, and CS1 required slighting the Mark 6 at times...
    "There are painters who transform the sun into a yellow spot, but there are others who, with the help of their art and their intelligence, transform a yellow spot into the sun." Pablo Picasso

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