CYGN-A

[laserist]

The BB4302 is just a ramp shaper. It was added at the output of the original ramp generator. The ramp will work fine without it... Sorry, I've had the bord wrapped up for a while. Something's been messing with my bandwidth.

[Greg]

The BB4302 is just a ramp shaper. It was added at the output of the original ramp generator. The ramp will work fine without it... Sorry, I've had the bord wrapped up for a while. Something's been messing with my bandwidth.

I didn't realize that. Cool! I'll get right on that. I can't wait to see the THAT 340 sing. Now it makes sense why there is Ramp Generator Output AND Ramp Output.

You know I'll be thrilled to receive anything that is sent, but please don't incur stress over shipping timelines. I have lots and lots to work on as is.

[Greg]

Here's the wiring diagram I've built the SPGN ramp generator circuit from. I haven't measured anything that looks like an oscillation in it though. The three CV inputs are getting about +5V. I'm not sure what to do with the digital ground. Investigation continues.

[laserist]

Digital and analog grounds are conected at a single point. It may not work without the reset signals hooked up to the 5012.

[mixedgas]

Digital and analog grounds are conected at a single point. It may not work without the reset signals hooked up to the 5012.

A4's wiring makes no sense to me. Ok, Edit, it does if the LM339 is a current sink...

Steve

[Greg]

Right again. The reset signals were among a number of things I was considering, and that was it. I'm about to enable the 4041 which is so old it came in a metal anti stat thing, and possibly a 555 to trigger it, and get the reset signals. Bypassing the 5012 (analog Switches) for testing, the ramp appears when reset is closed and inverted reset is open.

There is some sort of threshold involving the 3 CV generating pots I'm using. Haven't discerned whether it's ramp rate, slope, voltage level, or something else, but at some point as frequency increases, and / or time of ramp leg gets small, suddenly everything falls to ground and the current measured between -15V supply and negative rail of the circuit jumps from about 11mA to around 30mA. The circuit will stay in this state until the power is cycled.

You wrote:
Adjust the trim pot so the voltage at the test point is zero when the sweep data byte is 10000000 or maybe 01111111 (5v). At 5 Volts in there's no sweep. At zero it sweeps max. At 10 it sweeps max the other direction. (Not the other axis, that's what sweep direction does.)

This behavior will be looked for following the reset signals test.

The square wave in the photos is taken from spiral in CV input.

[laserist]

It's hard for me to look at that kind of drawing unless I'm prototyping the circuit. Look at it this way:



1/2 of A4 is an integrator. The other half is an inverting op-amp with an offset adjustment for the sweep signal (not in this image).

[Greg]

Looking at the hybrid cardcage system diagram, it's interesting to start to see how the SPIRAL X13 and other modules were controlled by the data. Being such a central feature of the 6b, the SPGN rebuild needs something in the way of simulated 351 synched to audio in order to properly explore the ways in which this spell was cast.

Thoughts welcome regarding a technical path to audio + choreography signals with reinventing the least number of wheels.

Attached graphic shows panel wiring for one oscillator of the CYGN-A. 4.7K for summing input seems to work, but I'm not sure that resistor value is specified in the docs I have.

Boards in progress shown. One board is a CYGN-A minus the ramp generator, 2 of 3 oscillators tested working. One oscillator uses the original vintage 4558 and 741 instead of a quad op amp. I don't expect to find a difference in performance, but this can be tested now. The other board is the bipolar ramp without reset, but with attenuation, offset, inversion, summing, etc. and also the SPGN amplitude modulation by 2x4QMM, the sweep summed in, and the 4x4QMM rotator from Brian's log book. The ramp from the actual SPGN can be input instead of the on board ramp.

[laserist]

I can send an unpopulated 352 pc board if you'd like one. I have some of the less available chips. The better way would be to employ a micro-controller and firmware. It's on my list, but I haven't even begun the prep work yet... While 8 bits was enough for Laserium (with really low pass filtering) going forward I'd want at least some 16 bit capability. And I really want the ability for selective real time editing of the data.

[Greg]

An unpopulated 352 pc board and rare parts is a good thing to have, though I think undertaking to rebuild the whole 352 infrastructure might not be the best use of my time, at least in the near future. We've seen in the past year that, with sufficient motivation and resources, the abstract generating hardware of years gone by can be brought back. What's a term that identifies the hypothetical system needed to bridge the currently available highly capable display hardware with the ancillary requirements of Ivan's vision of live laser performance as art that has proved so successful in the past? Ancillary requirements such as, as you mention, selective real time editing of choreography data, four channel bus architecture, choreographed control signals to devices, etc.

It might serve as a starting point to consider from a user interface perspective how selective real time editing of choreography data would best be achieved. Did you have experience working in the studios actually creating the data for the numbers?

Something I expect to attempt fairly soon is a discerning of the characteristics of the original colormod hardware in a way that can be implemented as faithfully as possible through modern digital means. There are some comments you made previously in other threads regarding this which I'll go collect.