Laser growing up

[lasermaster1977]

I always loved implementing the following analog console with a 4 channel PLL mixer where each channel could be independently set for Sine, Triangle or Square outputs and to harmonics 1-10. Locking PB's (ganged push-buttons) were used for those functions and provided the operator easy visual feedback for their settings. The 4 channels were in the form of Xo=(X1+X2) and Yo=(Y1+Y2) with slide pots for each axis plus an XoYo Master slide pot. A 10-turn Phase pot set the phase difference between the X1X2 and Y1Y2 pairs. Each channel could be switch selectable for PLL or free running. Free running used 10-turn pots that used the same 1-10 frequency ratio range. X1X2 followed the PLL reference frequency fixed-phase while a triangle-to-PWM circuit provided the PLL dynamic phase differencing for the Y1Y2 channels. Each XY pair could be independently (or ganged) for amplitude modulation with a 10 position SP10T coarse switch and a 10-turn Bourns pot for fine tuning, Sine or Square wave selectable. The final output was summed with a 4 channel joystick, each joystick XY channel having XY polarity selection plus selectable global damping levels. DAC imaging and Ramp waveform modulation was later added with an Apple II.

Later I digitized all of this using previously mentioned post in this forum consisting of 65C02 co-processor XY DACs, XY Scaling DACs, Sin/Cos/Ramp/Square wave shape tables and 64 programmable console/projector selector switch functions.

EDIT: I have to agree with kecked and laserist in that the immersive interaction of the artist/operator in the old days provided expressive opportunities that totally programmed shows may come close to it, but are hard to duplicate. From a music background, I found the immersive interaction of "switch and dial" manipulation to music to be the same as one playing a musical instrument in concert with others. All of my consoles, analog and digital/analog retained the ability to supplement pre-programmed content with live interactions.

[Greg]

lasermaster1977: I'm reading the description of your console a few times. What's PLL?

laserist: Fascinating as always, thank you! One thing I may be overlooking in your discussion of the triangle audio mod is the source of the fixed frequency signal that is modulated by the AM signal.

An other thing I may be overlooking in your discussion of the triangle audio mod is the mechanism of suppression of the amplitude modulated signal for slightly less than half of the sweep of the triangle. I remember that effect looked so appealing because the gain of the amplitude modulated carrier signal tapered off around the limits of the triangle sweep and bled slightly past the limits and into the flyback portion of the sweep.

[lasermaster1977]

lasermaster1977: I'm reading the description of your console a few times. What's PLL?

PLL=Phase Lock Loop

[laserist]

snip

laserist: Fascinating as always, thank you! One thing I may be overlooking in your discussion of the triangle audio mod is the source of the fixed frequency signal that is modulated by the AM signal.

An other thing I may be overlooking in your discussion of the triangle audio mod is the mechanism of suppression of the amplitude modulated signal for slightly less than half of the sweep of the triangle. I remember that effect looked so appealing because the gain of the amplitude modulated carrier signal tapered off around the limits of the triangle sweep and bled slightly past the limits and into the flyback portion of the sweep.

The "fixed frequency signal" is either the Audio Mod signal or a fixed cycloid multiplied by the Audio Mod signal. (Stock 6B consoles had 533 analog multiplier chips and there's no guarantee they were remotely trimmed correctly.)

[laserist]

I ran across an article about how architecture influenced music over the ages. With the advent of medium to huge Cathedrals with their stone and glass acoustically bright echoes the music of the times evolved to compliment the space. It is a reoccurring thing – example: Stadium Rock. Computers can have their own effect. And not just on music. Imagine a computer program where you can program the most impressive finger picking rifts on a virtual guitar, but the programmer never implemented the code for bending a string. You could produce some impressive stuff with the program, but you will never get it to gently weep. Adjusting multiple frequency controls to setup color mod seems like it gives a much greater degree of control, and I guess by some definition it does, but mostly it just hurts my eyes. One of the design philosophies behind Laserium’s user interface was don’t turn two (or more) controls when you can figure out a way do it with one. Once an effect requires both of your hands you can't do anything else...

[laserist]

I thought I'd put this up here - just in case anybody's interested:

[lasermaster1977]

I thought I'd put this up here - just in case anybody's interested:

Thanks for sharing, what fascinating insight into what Laserium laserists had for a playground. Now, is it remotely possibly to further share what some of those more obscure console labels meant and did?

[laserist]

Thanks for sharing, what fascinating insight into what Laserium laserists had for a playground. Now, is it remotely possibly to further share what some of those more obscure console labels meant and did?

Yes, but it's going to take several steps to lay things out in a way that avoids the whole I can't tell the forest from the trees confusion. I think the next steps include the 351 encoder/decoder, what laserium called the hybrid card cage,, and the upper card cage. The combination of those 3 major pieces and how the interact with the control panel should go a long way toward demystifying Laserium. That said it's pretty much in the patient 4,006970 except the patent didn't explicitly describe the controls, and there was a huge shift in Laser Images' performance philosophy from the Mark IV to the Mark VI.

[lasermaster1977]

Yes, but it's going to take several steps to lay things out in a way that avoids the whole a can't tell the forest from the trees confusion. I think the next steps include the 351 encoder/decoder, what laserium called the hybrid card cage,, and the upper card cage. The combination of those 3 major pieces and how the interact with the control panel should go a long way toward demystifying Laserium. That said it's pretty much in the patient 4,006970 except the patent didn't explicitly describe the controls, and there was a huge shift in Laser Images' performance philosophy from the Mark IV to the Mark VI.

Cool, more great info, thanks. I check out the patent first. Here's a neat YouTube video that sheds some interesting mathematical "lights".

https://www.youtube.com/watch?v=ds0cmAV-Yek

[laserist]

Cool, more great info, thanks. I check out the patent first. Here's a neat YouTube video that sheds some interesting mathematical "lights".

https://www.youtube.com/watch?v=ds0cmAV-Yek

Laser Images didn't remotely get into fourier analysis, we were much more likely to filter a square wave to get a sine wave. The analog cycloid generator (CYGN-A) was just three quadrature oscillators made up of three op-amps per oscillator. They did a decent job, and a slightly more expensive frequency potentiometer would have fixed my only small complaint.