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Thread: CYGN-A

  1. #101
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    Mar 2010
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    For the next part, boolean RYGB to RGB, each output (buffer needed?) generates RGB levels for each of the 4 colors using voltage dividers, 2 input summing amp each for red and green?
    Attached Thumbnails Attached Thumbnails colormod_to_RGB_4.png  

    colormod_to_RGB_demo_2.jpg  


  2. #102
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    Jun 2009
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    Since only one gate is on at a time. Three summing amps, red, green, & blue. Resistors between gates and appropriate summing amp.

    Gate. Amp.
    Red. Red.
    Yel. Red & Grn
    Grn. Grn.
    Blu. Blu.

    This editor strips the white space, why?
    Last edited by laserist; 04-29-2021 at 03:04.
    "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

  3. #103
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    Mar 2010
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    An update regarding the current scarcity of updates:

    The circuits that have been documented in this forum need to be assembled on prototype boards, and this will take at least a few more weeks.

    Once that is done, the following exciting milestones will become the priority:

    1) Continue exploring the choreography capabilities of the SPGN.

    2) Pre-build review of the Audio Mod board documentation.

    3) Interface Brian's design of the colormod signal source to an RGB projector. Spectacular results expected.

    The photo shows the complete CYGN-A board with card edge connector wired to the panel. After what appeared to be an impossible bug, I now know that 2x22 pin and 44 pin connectors are not the same thing.

    The oscilloscope photo of the well known lissajous shows what was used in the synthesizer bridge section of the number Turn Me On from Laserock2. I remember how much fun it was controlling the beat and the spin of the image while the data did sizes and beam kills.

    A number of the AB Modpots and ganged Clarostat pots on the panel appear rather worn (noisy, discontinuous). I'll look around to see what can be sourced.
    Attached Thumbnails Attached Thumbnails CYGN-A_complete.jpg  


  4. #104
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    Apr 2008
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    New Orleans
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    I have been enjoying reading all of your posts.
    Thanks for sharing all of your work and experimentation.
    Eric in New Orleans

  5. #105
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    Well, those pots are actually antiques. State electronics might be able to build up new equivalent units, but they would probably have a 50 unit min order. I'm guessing on the order of $10k. Try exercising the pots - turn them through their full range multiple times. One thing that would help is moving away from the original Laserium design. Good dual pots are expensive, and triples are even more expensive. AD633s are relatively inexpensive and allow you to buffer the pot with a voltage follower that will laugh at a little extra resistance under the wiper of the pot.
    "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

  6. #106
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    Mar 2010
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    Do AD633s offer a path around the 1meg dual reverse audio taper pots controlling the CYGN-A oscillator frequency?.

  7. #107
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    Check out page 11 of the AD633 Data Sheet.
    "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. #108
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    Mar 2010
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    djeric68, thanks for the encouragement!

    Regarding the FXCY, or Fixed Cycloid Card, it occurs to me to wonder about the role of the pulse-density modulation signal. I notice the following pins on the card edge:

    10: PDM enable
    H: PDM amplitude input
    S: PDM square wave input
    T: PDM buffered output (dated January 1982)

    and also of course, that the Spiral Gen. Card has
    S: PDM output.

    I forgot to look for the PDM signal when I previously got the SPGN ramp generator working.
    Last edited by Greg; 05-05-2021 at 21:52.

  9. #109
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    PDM is a square wave summed to one axis of the fixed cycloid signal. It was 1st used in Summer Madness in Laserium II. There was a 2QMM to control the gain and the frequency and duty cycle of the square wave depended on the spiral generator set up.

    The "D" might have been for deflection.
    "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

  10. #110
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    The PDM buffered output was added 12-1-82. The clipper card was added 12-7-82 as part of the Beatles Mods. And the clipper card has a PDM input. PDM was used for spiral blanking.
    "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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