CYGN-B

[Greg]

A decade has passed and I only now discovered a fascinating thread in which Laserist stated:

"Did you ever get a chance to look for a CYGN-B board or schematic? That's the digital cycloid generator that rode in the upper card cage of the Mark VI (& 600). The board itself is distinguished by several rows of 1/4 watt 1% resistors stretching top to bottom in three groups across the board… I'd really like to build an emulator of that beast…"

I have for four decades been haunted by the mystery of what this circuit actually was and how it achieved certain classes of images. For example, what I believe may have been referred to as the "bugoid" used in Lunar Sea in Starship. Another example, the walking clothes pin used in at least one early version of Walking On the Moon.

I didn't know until now that the "digital oscilator" ("b-mods"?) circuit was actually called CYGN-B.

Laserist, if you read this, your comments about the Johnson counter and the 555s syncing through the PS are the most interesting things I have ever read.

I have programmed an emulator that achieves, as far as I know, everything the original console was able to do, and more. If you happen to be interested, perhaps we could exchange details of the old for the new.

[laserist]

Actually I bought one of the original CYGN-B's from Jon back then. I think I sent it back with all the other hardware when I closed down Laserium here in St. Louis in 2014. And yes both of the images you mentioned were done with the CYGN-B. Those images involved an AM/FM image with the symmetry kicked over so only one axis was present and the other axis coming from the osc that was feeding the AM/FM signal. I've got a plan in mind for a CYGN-C that will do all that the -B did and a bunch more, but I haven't begun to prototype it. BTW it was -B because there was already a CYGN board in the system. The -B was part of the original Laserock mods which were the 6A mods - at some point they started referring to the system as a 6B, but we were up to 6F in my day. There were a lot of branches taken after my tenure, and I guess it just got too hard to keep track...

I began a software emulator ages ago that would look at digitized version of the old 351 data channel and generate frames to convert to video, but never took it too far.

The CYGN-C design involves dual buffered DACs, a microcontroller, and just enough glue to make it do tricks.

If there's anything I can do to help anybody move from offline to real time choreography I'm up for that...

Brian

[laserist]

This is an example of a frame from the software emulator...

[Greg]

I've attached two images. One is a photo of the panel that I have labeled with the control functions, as I remember them.

Second image is annotated output from my emulator showing how I get the bugoid and the clothes peg.

I have wondered much which oscillator's frequency provided the am and fm inputs to each oscillator. Do you remember how this worked? In the emulator output image I have included a chart indicating the patch I have found that makes possible both classes of images (bugoid and clothes peg) without having to be changed. How would that chart look in the original circuit?

Please pardon my ignorance, but is Jon a person I might contact and inquire to about the existence of an example of a CYGN-B? I know he was a party you spoke with in the thread from years ago. My holy grail would be to be able to schedule some tests on a functioning unit and an oscilloscope. I could make a fair offer if one could be found for $.

[Greg]

Mistake on the panel label image. Blue button is osc3 polarity.

[laserist]

The AM gain was the top knob, FM the lower knob. Osc 1 provided the AM/FM signal for osc 2, osc 2 provided AM/FM for osc 3, and osc 3 provided the AM/FM signal for osc 1. In no case was the AM/FM signal sinusoidal. Osc 2's triangle output was one source, Osc 1 & 2 were unipolar & bipolar square wave with a 50% duty cycle from the appropriate pin on the respective johnson counter. Both were buffered with an op-amp as I recall.

Jon is who Ivan turned over the company when he retired.

[laserist]

Jon is dsli_jon on photonlexicon. It wouldn't surprise me if he still had a board or two somewhere. I think I've got some of the old chips/transistors that went out of production over the years left from trying to cover all of the bases when I restored the 6b for the 40th anniversary in 2013. If worst comes to worst the documentation for pretty much everything was scanned and archived by Ron H. And the earliest boards were wire wrapped - geek artwork.

[Greg]

WOW, for four fifths of my life I have had empty fields in my brain awaiting this information on the modulation signals. I finally know! Thank you thank you thank you! It makes sense, the square wave would explain certain images I remember, but that don't seem to exist in the patches I have used with my emulator.

Again, please pardon my knowledge gap, but what does 351 refer to? I have two of the 4 track 1/4" reels, one from LaserockII and the other is probably Laserium '79. They do indeed have stereo audio, a guard track, and data on one track. It has been frustrating trying to find a studio that has a 4 track TEAC machine that actually works. Your idea for software that would look at digitized 351 data and decode the frames is interesting, I have thought about that as well. I've been told that the data is a spreadsheet of 32 bytes printed 30 times a second.

[Greg]

Regarding your CYGN-C design, have you considered BELA Low Latency as a platform?

[laserist]

351 or later 352 (same thing really, but one card instead of three.) was the name of laserium's data track. It was in a large way what separated Laserium from everybody else. Charlie McDaniel (Ivan's seriously techy partner who built that first actual projector) once told me the smartest thing they ever did was decide to emulate rather that record imagery. The 351 track contained rygb gain, master xy gain, spiral in, out, sweep, Danube rate, offset gain, and offset rate as 8 bit analog values with huge filters to smooth things out, as well as 32 bits (later 48) of housekeeping stuff. Think of it as the score as in an interpretive dance piece. It allowed someone in the studio to do the repetitive stuff while the Laserist did the "lead guitar". It was a brilliant approach... and nobody ever figured it out.