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Thread: CYGN-B

  1. #281
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    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Greg, check your email for circuit fragment images.
    You'll need a quad npn on a chip

    Steve
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  2. #282
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    First, thank you Steve, Brian, and Ron for the information you sent that will increase the probability of a successful rebuild of the SPGN (Spiral Generator Card).

    Second, for completeness, here is a photo of the CYGN-B unipolar and bipolar square waves which are used as modulation signals.

    Third, the build of the CYGN-B is now complete and testing, and the first results are in. Only problem is the not great oscilloscope I'm stuck with until I get home.

    The photo with the sequence of frames shows oscillator2 being dialed from full triangle wave through mix to full sine wave. The other photo shows a test of using modulation.

    People, there is nothing else like this circuit. Touch the dials, and one immediately is transported back to the days of the classic shows. It makes it abundantly clear what is unavailable to currently performing laserists. I'm amazed how different this is than the patch I set up on my cyc emulator. There is truly a universe of grooviness, a rich playground of signals to explore behind the panel.

    I wonder what poet wrote the intro line to Crystal Odyssey: You are about to dream of times and places that never were, and yet will always be
    Attached Thumbnails Attached Thumbnails CYGN-B_unipolar_and_bipolar_square_waves.jpg  

    CYGN-B_build_complete.jpg  

    CYGN-B_osc2_triangle_to_sine.jpg  

    CYGN-B_test.jpg  


  3. #283
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    Quote Originally Posted by Greg View Post
    First, tsnip

    The photo with the sequence of frames shows oscillator2 being dialed from full triangle wave through mix to full sine wave. The other photo shows a test of using modulation.

    Snip

    I wonder what poet wrote the intro line to Crystal Odyssey: You are about to dream of times and places that never were, and yet will always be
    It looks like there's a phasing problem there, triangle to tri/sine to sine alone by the original design went square - bigger rounded square - to smaller circle.

    I'm confident Ivan wrote Crystal Odyssey story line.

    And you're welcome.
    Last edited by laserist; 12-12-2020 at 08:11.
    "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

  4. #284
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    Any recommendations for or against trying to spray contact and head cleaner into noisy Allen Bradley mod pots?

    One interesting thing to note is that, while the AM dial controls depth of modulation only, the FM dial appears to control both depth of modulation, and the frequency of the modulated oscillator within a range. This makes introduction of FM to an image a more dynamic effect. There is uncertainty regarding whether the FM pot is supposed to be 10K (currently used) or 100K, and what difference this would make.

    Anyone remember what the trim pots on the CYGN-B board were supposed to adjust for?
    Attached Thumbnails Attached Thumbnails CYGN-B_osc1_am_and_fm.jpg  

    CYGN-B_osc2_bug.jpg  

    Last edited by Greg; 12-11-2020 at 03:01.

  5. #285
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    Quote Originally Posted by Greg View Post
    Any recommendations for or against trying to spray contact and head cleaner into noisy Allen Bradley mod pots?

    One interesting thing to note is that, while the AM dial controls depth of modulation only, the FM dial appears to control both depth of modulation, and the frequency of the modulated oscillator within a range. This makes introduction of FM to an image a more dynamic effect. There is uncertainty regarding whether the FM pot is supposed to be 10K (currently used) or 100K, and what difference this would make.

    Anyone remember what the trim pots on the CYGN-B board were supposed to adjust for?
    I normally turned the FM full on for most things. Otherwise there was no way to hit a known image with the ten turn pots. I'm sure I played the FM gain once in a while too. The pots are to match the frequencies so at 1000 on the ten turn dials the oscillators were approximately the same freq. If the top osc was at 800 and the center osc was at 200 and the center osc gain was up and AM & FM were full on the image had a single propeller look. (It may have been 1000 on the top osc - years...) There's a grease State Electronics used to recommend. I doubt tuner cleaner would hurt. I assume it's the gain and symmetry pots that are giving you issues. It helps to "exercise" them - turn them full scale multiple 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

  6. #286
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    Quote Originally Posted by Greg View Post
    snip

    One interesting thing to note is that, while the AM dial controls depth of modulation only, the FM dial appears to control both depth of modulation, and the frequency of the modulated oscillator within a range. This makes introduction of FM to an image a more dynamic effect. There is uncertainty regarding whether the FM pot is supposed to be 10K (currently used) or 100K, and what difference this would make.
    Snip
    The FM is just a signal summed with the VCO's input. I suppose you could adjust the duty cycles of the square waves to set a freq and duration effect, but it might multiply the range of oh no where's an attractive image beyond human tolerance.
    Last edited by laserist; 12-11-2020 at 13:06.
    "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

  7. #287
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    Quote Originally Posted by Greg View Post
    Any recommendations for or against trying to spray contact and head cleaner into noisy Allen Bradley mod pots?

    One interesting thing to note is that, while the AM dial controls depth of modulation only, the FM dial appears to control both depth of modulation, and the frequency of the modulated oscillator within a range. This makes introduction of FM to an image a more dynamic effect. There is uncertainty regarding whether the FM pot is supposed to be 10K (currently used) or 100K, and what difference this would make.

    Anyone remember what the trim pots on the CYGN-B board were supposed to adjust for?
    It’s important to recognize that the CYGN-B circuit is generating the waveforms with a Johnson counters and a resistor arrays. This means the waveforms are unipolar initially, and the offsets to make them bipolar are supplied as one function of the AM circuits which are also is the power supply for the cmos chips making up the Johnson counters. As the AM signal changes the output voltage of the Jonson counter changes which requires a different offset voltage to maintain a symmetrical bipolar output.

    The photos imply that the problem is only in the y axis waveform. Unless there’s a wiring problem, or something subtle to have a problem in only one output implies the flip flops. I’d try swapping U2 &, U3 from the center osc and one of the others. Maybe one of them has a problem at low voltage? That it’s only recovering in one case not two may imply a missing jumper where the Q and invQ lines are tied together?
    "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. #288
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    Quote Originally Posted by laserist View Post
    It’s important to recognize that the CYGN-B circuit is generating the waveforms with a Johnson counters and a resistor arrays. This means the waveforms are unipolar initially, and the offsets to make them bipolar are supplied as one function of the AM circuits which are also is the power supply for the cmos chips making up the Johnson counters. As the AM signal changes the output voltage of the Jonson counter changes which requires a different offset voltage to maintain a symmetrical bipolar output.

    The photos imply that the problem is only in the y axis waveform. Unless there’s a wiring problem, or something subtle to have a problem in only one output implies the flip flops. I’d try swapping U2 &, U3 from the center osc and one of the others. Maybe one of them has a problem at low voltage? That it’s only recovering in one case not two may imply a missing jumper where the Q and invQ lines are tied together?
    I appreciate the bug hunting suggestions, which confirmed my line of thinking. Swapping all the chips in the counter produced no change. A thorough verification of the osc2 resistor network wiring (photo attached) exposed no error. So I have swapped the counter in osc3 for the counter in osc2 (photo attached), and the bug is present, which is good. This means there is a wiring error in the counter, and I have two working ones to compare against so the problem can't hide for much longer.

    The other photo shows the classic CYGN-B 3D effect involving modulation and kicked over symmetries. I always wondered if the designer of this circuit had this 3D effect in mind and designed the circuit to produce it, or if it was discovered later by exploration.

    Also: Thank you Ron! And Brian for the panel! A CYGN-A is looking like a possible rebuild.
    Attached Thumbnails Attached Thumbnails CYGN-B_osc2_resistor_network_wiring.jpg  

    CYGN-B_swap_osc3_for_osc2_counter.jpg  

    CYGN-B_test_3D_effect.jpg  

    tiny_resonator.jpg  


  9. #289
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    At last there is news. The issue with oscillator 2 "dropping a point" is present when the 74C164 8 bit shift register from a different manufacturer is used. (photo attached) If anybody out there has the one I need, please name your price and multiply by ten.

    Substitution suggestions welcome also.

    The point of constructing an original CYGN-B was so I could perform tests on the circuit to have certainty that the cyc emulator (my software) produces a faithful output. The circuit works well enough that these tests can be performed, and the results will be posted. There is an effect unique to the CYGN-B in which a point slowly and fluidly drips over the digital edge, as it were. I doubt this will fall out simply in emulation.
    Attached Thumbnails Attached Thumbnails CYGN-B_no_substitution.jpg  


  10. #290
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    Quote Originally Posted by Greg View Post
    At last there is news. The issue with oscillator 2 "dropping a point" is present when the 74C164 8 bit shift register from a different manufacturer is used. (photo attached) If anybody out there has the one I need, please name your price and multiply by ten.

    Substitution suggestions welcome also.


    The point of constructing an original CYGN-B was so I could perform tests on the circuit to have certainty that the cyc emulator (my software) produces a faithful output. The circuit works well enough that these tests can be performed, and the results will be posted. There is an effect unique to the CYGN-B in which a point slowly and fluidly drips over the digital edge, as it were. I doubt this will fall out simply in emulation.
    I looked through my stuff - no joy - perhaps Jon?

    Still they're not unobtainable yet:
    https://www.ebay.com/sch/i.html?_nkw...57.m4084.l1313

    What made the CYGN-B's look was the clock circuit and the low resolution DAC. (Okay and the FM & AM, but the FM was part of the clock curcuit, and AM is easy.) I've been planning a version using a similar clock circuit and double buffered DACS. The clock will be tied to the LDAC line of the DACs. And a microcontroller loads the next poiint when needed. I'm thinking of having a cmos version of the clock so it can emulate the CYGN-A using a higher resolution look up table. A guy has got to have a hobby...
    Last edited by laserist; 12-22-2020 at 00:10.
    "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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