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Thread: CYGN-B

  1. #211
    Join Date
    Mar 2010
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    Should have mentioned:

    Thank you Steve, for providing some scientific papers in which the black magic underlying the design of this circuit is revealed.

    A while ago in this thread, dsli_jon posted, and I didn't recognize who it was. I was confused when he mentioned we may have previously spoken, and wrongly concluded it was someone else. Thus, my reply was flippant, and made no sense. Jon and I have recently spoken, and the misunderstanding was resolved.

    I have been a bit worried that at some point someone could demand I stop reverse engineering their IP, but after an exchange with Jon, I don't think that will be the case.

    Ron, that's super helpful. I was wishing I had a better photo of the back, and there it was!

    There is previously unknown lore surfacing in this discussion, and Brian, your technical points, as always, are much appreciated. Thanks for posting, everyone.

  2. #212
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    Mar 2010
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    Arrow

    I had forgotten about the beam torquer. Now I remember operating that dial. That was my first encounter with the word torque.

  3. #213
    Join Date
    Jun 2009
    Location
    St. Louis, MO
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    I'm glad you got a chance to talk to Jon. I would have been high and dry if he hadn't stepped up.
    "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. #214
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    Mar 2010
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    See pic. (Sad trumpet sound.)
    Attached Thumbnails Attached Thumbnails DigiMax_vs_8BSS.jpg  


  5. #215
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    Mar 2010
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    Update: The correct boards have been re-shipped. I'll be back from travels in early September and will resume posts on the building of the CYGN-B at that time.

  6. #216
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    Mar 2010
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    Home at last. All the parts needed to build the CYGN-B have been mustered. Also, a real unpopulated CYGN-B board has been made available for reference. Also the stereo DACs for the C64 to poduce DOGN signal are here.

    Any shipments waiting my invite now have it.
    Attached Thumbnails Attached Thumbnails CYGN-B_build.jpg  


  7. #217
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    Mar 2010
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    That's the +-15 power supply in back in the photo.

  8. #218
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    Mar 2010
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    Oscillator 1 of the CYGN-B (photo of build progress attached) should be testing within a week.

    Steve, Jon, Ron, Brian, and others following, I hope you are weathering the tumult of the times and the world with sufficient peace in your lives to find interest in the forthcoming fruits of this restoration effort.
    Attached Thumbnails Attached Thumbnails CYGN_B_build_osc1.jpg  


  9. #219
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    Mar 2010
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    Oscillator 1 of the CYGN-B has been assembled on the breadboard. With a variable resistor added between pin 7 and ground, the 555 appears to be functioning as a VCO, and a train of negative going pulses exists on the collector of Q2, which is the line that provides the clock signal, but the shift register and the rest of the circuit doesn't seem to be doing anything interesting. Investigation continues.

  10. #220
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    Mar 2010
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    I obtained readings from all the pins in the 8 bit shift register. The clock signal is arriving at pin 8 (clock). All the bit output pins are sitting at ground, so the Johnson counter is obviously not functioning. Pin 9 (clear) is also sitting at ground, which is preventing the circuit from operating. Upon lifting clear from ground, the circuit produced the digital sine wave as seen in the photo. This is a good result. One axis of one oscillator of an authentic CYGN-B is generating it's output!

    There is no signal present at the cosine and inverted sine outputs, but this I expect will resolve with further trouble shooting.

    I do have a request for wisdom however, if anyone still retains a deeper understanding of how this works. The curious little N channel dual gate depletion mode MOSFET that pulls all the clear pins to ground, and had to be lifted for the circuit to work, seems like it is supposed to perform a global clear of the counter under certain conditions, but why, and when?

    Next task is to investigate the MOSFET and verify that the leads have been correctly identified.
    Attached Thumbnails Attached Thumbnails CYGN_B_output_sine_osc1.jpg  


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