15kpps scanner signal, what are the values?

[lasermaster1977]

Okay, phew! Glad we are on the same page. At my age I find it worth while to check and double-check. Today's laser technology just blows my away but see caveat at the end.

Woah! Wait just a second... Alden? That you? If so, then I've got egg on my face! When I suggested to Neil that you check this thread out, my intention was for you and Andrew to discuss things... He's way, *way* better at this than I am!

No worries, I'm just an ol' fart "has been" now anyway and you too get a lot of respect from forum users here, so don't be shy.

That will work just fine. However, unlike the circuit you're describing, the ILDA X and Y position signals we've been talking about in this thread are not limited by zero. They can swing positive and negative, which is why you get the wider voltage range at the output of the receiver. But yeah, for color signals the plan you have will work provided that both outputs are prevented from crossing the zero point.

Yes, indeed, I'm aware XY are bi-polar.

both +10 and -10 are possible, so at the receiver end the total swing can be up to 20 volts peak-to-peak.

Yes indeed, since the TL084 and other op-amp packages support + and - 18v supplies and larger they are capable of larger swings like you state. I was still focusing on the standard.

Interesting side note though: Many modern controllers no longer implement differential signalling for color, in direct contradiction of the ILDA standard. Since nearly all laser drivers use single-ended zero to +5 volts for color modulation, companies started deviating from the published ILDA spec and began using single-ended signaling for color. In fact, I have several QM2000 boards in my collection that actually have the negative color signal pins internally connected to pin 25 (ILDA ground). But they work just fine with all my projectors.

Geez, that sure makes things so much easier and that clarification is like gold to me.

It is good to know that the ILDA standard isn't hard and fast in terms of intensity control or blanking. I have seen the older, original copy of the ILDA Projector Standard but have been referring to Revision 002 from 1999 and it so states intensity signals are 0 to +5v. Is there a later version of the ILDA Projector Standard available?

Caveat: I just learned of the 4.0 release of Quickshow, so I updated my 3.0 to it, then watched Pangolin's "what's new" video. I chuckled a bit when I saw their new "parametric images" features, something I was doing back in '85-'88 in my laser shows with the Apple IIe. I did conceptual programming of parametric images in '84 on a large computer. See example attached from '84. I post a video excerpt from a Xmas show I did in '88 showing more examples soon.

[buffo]

At my age I find it worth while to check and double-check.

HAHA! You and me both, pal. Hell, I thought I had a pretty good handle on this stuff right up until Andrew pointed out a mistake in the first circuit I posted. Because I hadn't actually built that one, I couldn't prove it was right, but I also couldn't see how it was different from the second circuit I posted, which I *knew* worked perfectly. That led to an interesting conversation that showed me a whole new way to look at op-amps!

Today's laser technology just blows me away

Dude... We have *GOT* to get you to SELEM! You'll absolutely shit! (And I mean that in a good way...)

I'm just an ol' fart "has been" now anyway and you too get a lot of respect from forum users here, so don't be shy.

The difference is that you're an old fart who has been there, done that, and been a part of some amazing tech (and stunning shows) for a long time. I may be in the same generation, but I don't have anywhere near that level of experience. So you're an experienced old fart, and I'm just an old fart!

I have seen the older, original copy of the ILDA Projector Standard but have been referring to Revision 002 from 1999 and it so states intensity signals are 0 to +5v. Is there a later version of the ILDA Projector Standard available?

According to the ILDA website, Revision 2, from 1999, is the latest version of the Projector Standard.
So, yeah, "You've got the right one baby... Uh Huh!" (with 100% nutrasweet)

I just learned of the 4.0 release of Quickshow, so I updated my 3.0 to it, then watched Pangolin's "what's new" video. I chuckled a bit when I saw their new "parametric images" features, something I was doing back in '85-'88 in my laser shows with the Apple IIe.

Everything old is new again! Seriously though, many of the old school analog effects (especially abstracts) are now making a comeback.

Those parametric images weren't easy to set up in either Quickshow or Beyond, at least not before this update. But I've seen them done mathematically using other laser show software.

Now we need a tool to instantly map the colors from an image file to the parametric image. Parametric rasters!

Adam

[lasermaster1977]

Dude... We have *GOT* to get you to SELEM! You'll absolutely shit! (And I mean that in a good way...)

Sounds like an expensive but exhilarating week. Early registration $110 or so, hotel and meals for 4-5 days, round trip airfare (god only knows)? $1K total? For me driving from Colorado is far less expensive but more time on the road round trip.

Those parametric images weren't easy to set up in either Quickshow or Beyond, at least not before this update.

I hooked up my projector with QS 4.0 last night and played with the parametric images, but I didn't think it as easy as I first thought it might be. There seem to be some basic tried and true harmonic relationship parameters that are not provided as an easy way to "hit" on them or "close to them". You still have to "hunt" for them, but at least it is a better user interface.

Everything old is new again! Seriously though, many of the old school analog effects (especially abstracts) are now making a comeback.

It great to hear that it is and I think swamidog's amazing LSX shows are a testament to that, too! I've also been impressed with some forum members analog console photos. My original ones used a summing combinations of PLL Sine, Triangle, Square function generators for X and Y, multiple sine, square function generators for AM'ing some or all of the XY outputs, along with DC joysticks with selective damping and selectability of all this for what each RYGB color scanners received and finally two PWM saw-tooth chopper wheels for blanking. Pushing the saw-tooth wheel and motor (mounted on a motorized lead screw) further into the beam changed the blanking duty-cycle. The chopper wheels eventually were replaced by AOM's, and all the function generators including added ramp waveforms were replaced with DACs, Apple and software.

[aberry]

Interesting side note though: Many modern controllers no longer implement differential signalling for color, in direct contradiction of the ILDA standard.

Are there any modern light show controllers that still do emit differential color signals? Given that a differential receiver will handle single-ended transmission, but a single-ended receiver will not handle differential transmission, and the fact that the color signals in light show use are going to have a much higher threshold before interference becomes objectionable than X/Y signals, I don't think there's really any benefit to implementing differential color transmission in controllers. Besides, if you've got long runs in adverse environments ILDA certainly wouldn't be my first choice these days...

[lasermaster1977]

but a single-ended receiver will not handle differential transmission,........I don't think there's really any benefit to implementing differential color transmission in controllers. Besides, if you've got long runs in adverse environments ILDA certainly wouldn't be my first choice these days...

But a single ended receiver can be made or modified to receive differential inputs easily.

Consider ye 'ol phone company telephone lines. They used and still use 600 ohm balanced lines (differential outputs) for each phone conversation on only one twisted pair of wires, over hundreds of miles of length in many cases with no objectionable noise or hum pick up. ILDA is a 300 ohm balanced line making noise pickup more unlikely and still cancelling out any common mode noise on both + and - wires.

True, there is less benefit when an Ethernet laser DAC is built-in to the projector or couples to an external Ethernet DAC with very short ILDA or parallel equivalent cable connecting to a projector's ILDA port. Single-ended color signals are at very low risk for noise pick-up. BTW: Ethernet also uses balanced line driving using only twisted pair, unshielded cables with dedicated pairs for transmit and receive, making them very good long haul cables with great noise immunity for up to 100 meters. So there is great benefit to "differential" balanced line driver technology specifically due to excellent noise immunity.

[lasermaster1977]

The difference is that you're an old fart who has been there, done that, and been a part of some amazing tech (and stunning shows) for a long time.

I did this amazing technology for about 14 years all total, and I certainly do not want to compare myself to those who did it a lifetime 25 year or greater career (like photonbeam and others like him). They are the true been there, done that ol' farts.

[lasermaster1977]

Sounds like an expensive but exhilarating week.

I checked on round trip airfares, about $225, not bad. What do hotel rates run per night?

[buffo]

SELEM sounds like an expensive but exhilarating week.

By the time you factor in hotels, travel costs, and everything else, yeah, it does get a little pricey. But don't think about it in terms of attending a conference or training seminar (because it's not like that at all). Instead, think of it like a summer vacation. Then it's easier to justify the expense.

And trust me, SELEM absolutely qualifies as entertainment! I tell people that it's not even about the lasers. It's about the human element, the social interaction, the sheer joy of sharing something you're passionate about with other people who are equally passionate about the same thing. Of course, there's also the lasers, and the tech, and the art, but the most important part is the *FUN*.

I checked on round trip airfares, about $225, not bad. What do hotel rates run per night?

Depends on where you stay. High end is the Holiday Inn Express and Suites, which runs between $105 (standard room) and $125 (suite) per night. Most people stay there because it's just 5 miles from the venue and it's a really nice place. Also, since most people stay there, everyone ends up at breakfast at more or less the same time, plus we always have a few die-hards who gather in the lobby late at night after SELEM ends and they stay up even later because they're too excited to sleep. Often times the late-night crowd ends up having breakfast with the rest of the group at 6 AM!

However, there are plenty of other, more affordable places within a few miles if you don't want to stay at the Holiday Inn. Low end is probably something like $65 per night, although you might get an even better rate if you look for an Air-Bnb. Something else to consider: if you want to stay at the Holiday Inn (to reap the benefits of being with the others), note that you can save a ton of money if you simply split a room with someone else. (This really works out well with a suite, where 3 people can split a room for under $45 per night each. One guy sleeps on the sofa-bed...)

For me driving from Colorado is far less expensive but more time on the road round trip.

Driving is great if you plan to bring a lot of equipment, but as you said it takes up more time. And then there's the extra cost of the hotels (and gas) during the trip out and back. Honestly, driving probably costs more than flying when you add it all up, so unless you need to bring lots of gear, you're probably better off flying. Note that if you stay at the Holiday Inn, you can almost always catch a ride to and from the Auditorium each day with one of the other SELEM attendees.

Re: Renewed interest in abstracts... I think swamidog's amazing LSX shows are a testament to that, too!

Don't forget what SaltyRobot has been doing lately!

I've also been impressed with some forum members analog console photos.

If you dig consoles, then you really need to sit down with DZ and have him walk you through the Z5 console. It's amazing! Then you need to sit down with Aron Bacs (formerly of AVI) and have him show you the analog software he's been writing. (Equally amazing, and even faster to make changes to!) But the coolest part is that after you've chatted a bit you can actually put your hands on the stuff and play with it... *THAT* is just a small part of what makes SELEM so special. You meet the guy who built a thing, he tells you how it works, and then he lets you mess around with it. And after 10 minutes you're thinking to yourself, "I need to get one of these....", or even, "I could build one of these myself, and add some new features too!"

My original ones used a summing combinations of PLL Sine, Triangle, Square function generators for X and Y, multiple sine, square function generators for AM'ing some or all of the XY outputs, along with DC joysticks with selective damping and selectability of all this for what each RYGB color scanners received and finally two PWM saw-tooth chopper wheels for blanking. Pushing the saw-tooth wheel and motor (mounted on a motorized lead screw) further into the beam changed the blanking duty-cycle.

Sounds similar to the P4 design (upon which the Z5 is based). SaltyRobot has his own console that is very different, but it has elements that are similar to what you're describing. Last year his father had another console design from the 1980's that was more modular, but even that one still had some of the same building blocks. (I don't know if that unit will be making a return this year or not though - it had quite a few parts and filled most of a 5 ft table.)

all the function generators including added ramp waveforms were replaced with DACs, Apple and software.

That's the route that Aron Bacs took with the software he's been writing... Model everything mathematically in software and sent the output through a sound card. (BlueFang did more or less the same thing with his Maxwell software.) Amazing what you can do with modern CPUs though!

Are there any modern light show controllers that still do emit differential color signals?

I honestly don't know. Maybe Lasergraph DSP? The differential color standard is pretty old. (Especially since the current single-ended standard dates all the way back to 1999!) I seem to remember that the French "AA" branded PCAOMs were designed to accept a differential color modulation signal though, so it's possible that there are still some controllers that support it.

Adam

[lasermaster1977]

By the time you factor in hotels, travel costs, and everything else, yeah, it does get a little pricey. But don't think about it in terms of attending a conference or training seminar (because it's not like that at all). Instead, think of it like a summer vacation. Then it's easier to justify the expense.

Thanks Adam, I appreciate the further insights to SELEM. The cool thing is, that if you're still in the biz, it's an amazing write-off. (so...if I do one show a year, and it takes me 10 months to prepare for the show...then SELEM is a tax write-off!)
I'll get there eventually, I'll betcha.

Darn right, I'd love to see Aron and Saltyrobot's works.

Thanks again!