CYGN-B

[Greg]

Wiring error discovered. Photo shows the sine and cosine. Huzzah!

[Greg]

These photos show the AM function of oscillator 1 being tested with a signal from a function generator. One great feature of the CYGN-B is how the oscillators perform all the way down to zero frequency. When the wiper meets the rail, the dot stops where it is. This effect, seen here as some sweeping bars by adding AM to an oscillator tweaked at a very low frequency, was used in the Hendrix number in LaserockII.

[ronhip]

Greg,

Great progress! I haven't been looking at PL for a week or so. I'm very impressed with the number of prototyping boards you have arrayed out in front of your oscilloscope. Way beyond what I'd imagine anyone would do. Of course, what you see on your 'scope is not quite what you'll see with scanners. Electron beams don't have the inertia of ballistic scanners!

Great job!

Ron

These photos show the AM function of oscillator 1 being tested with a signal from a function generator. One great feature of the CYGN-B is how the oscillators perform all the way down to zero frequency. When the wiper meets the rail, the dot stops where it is. This effect, seen here as some sweeping bars by adding AM to an oscillator tweaked at a very low frequency, was used in the Hendrix number in LaserockII.

[Greg]

Thanks Ron! I'm glad you're still here. I thought of something that would be fun to see posted here if you happen to find one in your archive: a photo of the ringing KQO. That would be the first thing I'd look for if I ever gain access to more of the documentation that has been so generously provided by contributors. The image rotator is another thing that would go really well with a working CYGN-B.

I have concluded testing of the Oscillaror1 of the CYGN-B. It is fully functional, but a mystery remains. The entire circuit involving the SD305 MOSFET, a resistor, a capacitor, a signal line from the counter, and the clear line of the counter, appears to be superfluous. The oscillator runs fine with this part of the circuit removed, but can't function with it, as the MOSFET simply holds the clear pins low, which is a perpetual clear. I can guess the purpose is to initialize the counter with a clear on power up, after which the MOSFET is supposed to function in some sort of monostable way, and keep the connection between the clear pins and ground open. It doesn't want to work this way though, so I'm leaving it out of the current build.

Interesting updates on the CYGN-B may take some time to appear, because the next phase of the project involves documenting and hard wiring this oscillator, and a duplicate for oscillator 3, before building the more complex oscillator 2 with it's famously useless triangle wave output (though that effect was great in the introduction to Turn Me On by The Tubes.)

More good news on another front: I expected the quest for stereo DAC output on the C64 to be a high hurdle, but the DigiMAX seems likely to do the trick, as I have plugged in sample code from MadModders available here:

https://www.youtube.com/watch?reload=9&v=GZsFehLtsqU

and the first run produced a great result: Wiggled first one channel, then repeatedly wiggled the other channel. This means that viewing the dogloids on an oscilloscope may not be far away.

[mixedgas]

Normally I'd use Eproms or SIn/Cos in analog for that. But the CYGN waveform looks so good when modulated that I just ordered a bunch of shift registers and precision resistors.. Here we go... Mine will use similar building blocks but will not be a CYGN-B. We loves us our Laserium., So I will be honored to have that distinct waveform. I went back and read that article I sent you, mines a 24 instead of 36 point, but no depletion MOSFET. Folks who use old style DMs regularly tell me they can be sloppy on tolerances due to the problems with the older P channel process used.

Cheers Greg!

Steve

[mixedgas]

Since this was pre-ilda, what did Laserium use as a test pattern to tune scanners to?

Steve

[ronhip]

Steve,

Brian, please correct me if I'm mis-remembering things. When we started with our open-loop scanners, we had a special card that we plugged into the card cage somewhere (???) and it put out a 4-point square image. We tuned our home-built amps to get *just* the right ringing of the scanners at the corners of the square. Wait... Let me look into the Mark IV documentation I have here... Nope. I have schematics, but no alignment procedures. I'm barely remembering some pre-programmed pre-ILDA test pattern that we used for aligning our in-house closed-loop scan-amps, but it's been too long (It's been over 20 years (!!!) since I performed Laserium shows.) That test pattern may be on some video tape I digitized for our Laserium archive, but it would take a long time to find. If I run across it, I'll post it.

Ron

Since this was pre-ilda, what did Laserium use as a test pattern to tune scanners to?

Steve

[mixedgas]

Ok, so two flip-flop walking ring counter to make the quad square. I've done that before. I figured one of the keys to the beautiful images was ringing on the open loop. I have a pile of open loop scanners and I know how to add the damping. So basically an General Scanning A106 amplifier with just servo, offset, and damping,. No wonder modern galvos have that "too perfect" look on consoles. Thank you for letting me know.

For those of you going" say what" older galvos have a torsion bar to return the shaft to the center position, and it can add all sorts of ringing and harmonics to an image. Modern galvos don't need it, the position sensor and servo loop forms a virtual spring.

So now I just need to figure out the joystick and offset, and how the splits to the four scan heads worked. I have an idea of how to do it with op-amps.

What do you call it when the 4 colors go off from center in symmetry with the same image ??? It is my favorite effect.. Its what got me interested in like 1986 or so. It led to a career. Pink Floyd's song Sheep, with a still frame of a 8 bit sheep outline, going from an overlapped white sheep, out to one up, one down, one left, one right, translating out from center, and spinning, on the way. Of course with one in red, one in green, one in blue, one in yellow on Lumia. That one and Blue Danube.. Between Buhl and Bradenton, lasers on weekends and lasers on vacation got me hooked...

"Get a "B" average or better in your Junior Year, I'll get you the HENE".. Love, Dad..

Steve

[laserist]

Steve,

Brian, please correct me if I'm mis-remembering things. When we started with our open-loop scanners, we had a special card that we plugged into the card cage somewhere (???) and it put out a 4-point square image. We tuned our home-built amps to get *just* the right ringing of the scanners at the corners of the square. Wait... Let me look into the Mark IV documentation I have here... Nope. I have schematics, but no alignment procedures. I'm barely remembering some pre-programmed pre-ILDA test pattern that we used for aligning our in-house closed-loop scan-amps, but it's been too long (It's been over 20 years (!!!) since I performed Laserium shows.) That test pattern may be on some video tape I digitized for our Laserium archive, but it would take a long time to find. If I run across it, I'll post it.

Ron

There was an alignment board that plugged into the multiplier summer position that had 8 toggle switches to insert a square wave at the 4 x/y outputs. The damping was adjusted to center the ringing of the square wave. The CYGN-B wasn't really all that influenced by damping. The dogloids were where the damping (or lack of damping) would really show an effect.

[laserist]

Ok, so two flip-flop walking ring counter to make the quad square. I've done that before. I figured one of the keys to the beautiful images was ringing on the open loop. I have a pile of open loop scanners and I know how to add the damping. So basically an General Scanning A106 amplifier with just servo, offset, and damping,. No wonder modern galvos have that "too perfect" look on consoles. Thank you for letting me know.

For those of you going" say what" older galvos have a torsion bar to return the shaft to the center position, and it can add all sorts of ringing and harmonics to an image. Modern galvos don't need it, the position sensor and servo loop forms a virtual spring.

So now I just need to figure out the joystick and offset, and how the splits to the four scan heads worked. I have an idea of how to do it with op-amps.

What do you call it when the 4 colors go off from center in symmetry with the same image ??? It is my favorite effect.. Its what got me interested in like 1986 or so. It led to a career. Pink Floyd's song Sheep, with a still frame of a 8 bit sheep outline, going from an overlapped white sheep, out to one up, one down, one left, one right, translating out from center, and spinning, on the way. Of course with one in red, one in green, one in blue, one in yellow on Lumia. That one and Blue Danube.. Between Buhl and Bradenton, lasers on weekends and lasers on vacation got me hooked...

"Get a "B" average or better in your Junior Year, I'll get you the HENE".. Love, Dad..

Steve

Laserium had fixed rotation option for each color that was done with op-amp "networks". Variable rotation done with 4 quadrant multipliers.

I think you're talking about swept spirals... or just swept offsets.