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Thread: "KPPS" technical definition/question

  1. #11
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    One neat thing about PROPERLY TUNED modern galvos, if not fed ultra sharp high frequency square waves, they tend to survive anything you throw at them, especially if there are size pots between the signal source and the galvo amp. A dual 10K or 100K audio taper pot makes a great XY size control. The one radio shack sells for 3$ will enable your experiment.

    A few years ago before a recent price fall in some controllers, I looked long and hard at a Zektor(tm) vector controller, but would have needed some one to write some Windows code. I had a skilled person in mind who could write that code, but he turned out to be a real failure when working with others and I canceled the project. The Zektor folks were not so keen on trying,and I did not feel like loaning them a 700$ pair of galvos at the time, so the project stopped. But at the time I did not see any obvious problems using the Zektor for laser with a few minor mods.

    What I'd saying is it can't hurt to try if you keep the initial angles down using the size controls.

    Newer galvo amps, as my Friend Andrew often reminds me, are more PII, then PID, so they tend to not launch into oscillation with rough drive waveforms.

    Start with a circle. Work up from there.

    Worse comes to worse you may need to play with/remove/increase your integration cap on your generator.

    As to just turning the speed down, yes, just expect to perhaps have to do some amplifier tuning on the small jumps. Its not a big deal, three 10 turn trim pots. Since you already have a oscilloscope, one of the techniques we use is to tune one axis on a square wave for the least ringing and overshoot, while watching the feedback signal. So you can match velocities if you need to, but I bet you can just lower your speed and make changes to the image. So what, if you loose 10% of the scanner's performance, no big deal. In reality everybody opens up the angle and reduces the scan speed, ILDA 30K is really a data interchange format if you think about it. You tune to 30K/8' to share images correctly, more then anything else. When you run a show you most likely open up to 15-20' and the PPS rate comes down, mathematically the angle multiplied by PPS is roughly a constant, so as you increase angle, point rate falls off. Its not directly a linear function, but it does happen.

    For those wondering what a Zektor is:

    http://www.zektor.com/zvg/downloads.htm

    Steve
    Last edited by mixedgas; 09-09-2010 at 10:33.
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  2. #12
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    Quote Originally Posted by mixedgas View Post
    A few years ago before a recent price fall in some controllers, I looked long and hard at a Zektor(tm) vector controller, but would have needed some one to write some Windows code.
    Hahahah... Small world! I've known Zonn for *years* on the arcade game side of things. One of my business partners actually did the PC-side development for the ZVG back in the day. (Nasty, parallel port business such that is was. ;-)

    Zonn and I had a (friendly) holy war going on for ages about analog vs. digital vector generators. Zonn implemented sort-of a modern take on the Cinematronics vector generator for the ZVG. I basically advocated a modern digital update of the basic design from Atari or Sega's digital vector generators. (ie, no integration caps, just direct high speed DAC control)

    Since Zonn actually shipped the ZVG as a product though, he wins the debate by default. ;-)

    Anyway... I'm still doing gaming stuff, so basically I'm just looking to find another fun use for the technology-- and I've always wanted to have a laser scanner...

    Thanks for the pointer on the RS pots. There's a few parts they still sell that are useful after all. :-)

    I'll take it slow and see how it goes. I'm really looking to do original projected laser games (we own an arcade and need some neat wall/ceiling "decoration") but using our own hardware platform instead of a PC based setup.

    -Clay

  3. #13
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    Keep us informed. Laser Mame and LazyMame are BIG favorites around here. As is Lasertennis and Asteroids, the Pangolin and Zoof versions.

    Where are you at? It is possible that a PLer could stop by with a pair of galvos.


    Steve
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    Quote Originally Posted by mixedgas View Post
    Keep us informed. Laser Mame and LazyMame are BIG favorites around here. As is Lasertennis and Asteroids, the Pangolin and Zoof versions.

    Where are you at? It is possible that a PLer could stop by with a pair of galvos.


    Steve
    Is there a Lasertennis for the LD2000?
    leading in trailing technology

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    Quote Originally Posted by mixedgas View Post
    Where are you at? It is possible that a PLer could stop by with a pair of galvos.
    I'm in the Portland,OR area (Vancouver, WA actually-- but so close as to make no difference). Our arcade is in Portland (Ground Kontrol).

    I actually bought a couple systems off eBay to mess with so I'm "dangerous" if not necessarily knowledgeable at this point.

    My business partners and I design and build the hardware/software that's inside a lot of commercial arcade stuff (if you ever see the "Arcade Legends"/"Ultimate Arcade"/"Extreme Arcade"/"Golden Tee Clubhouse" machines at places like Costco, Sears, Sports Authority, etc. those run our hardware/software inside.

    I just like having little low-power, low-cost dedicated hardware to run things instead of PC's, so that's pretty much what I'm doing. I've written "Vector Breakout" (ran on an Atari Tempest machine) and a few games that run on the Vectrex game system ("Moon Lander", etc.), so I want to try getting some of those going with the laser instead. ;-)

    There's a pic of Vector Breakout here:


    And someone put up a video of Moon Lander running on the real Vectrex hardware here:


    ...anyway-- I'll undoubtedly need to ask some more questions and muck about a bunch before I get anything worth sharing. ;-) Probably run everything on a scope just to be safe for a while!

    I know that *years* ago some guys tried running Vector Breakout on a laser setup at the California Extreme (arcade gaming) show. (Might have been around 1999 or 2000?) I tweaked a lot of the code there to get rid of long jumps and extra stuff so it would hold up framerate better, but I have no doubt that things on the laser scanner side are 10x better/faster/cheaper now!

    -Clay

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    Wouldn't it be awesome if this game would be ported to laser display ?


  7. #17
    mixedgas's Avatar
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    Portland/Vanc area? There are at least 4 laserists in your area.

    Come on WA laserists, at least one of you would like to see laser arcade games, help this guy out!

    Steve
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    Quote Originally Posted by mixedgas View Post
    Portland/Vanc area? There are at least 4 laserists in your area.

    Come on WA laserists, at least one of you would like to see laser arcade games, help this guy out!
    Good to know! I'm not in a huge rush just yet (waiting on some PCB's and components and some extra time to work on stuff!), but knowing there's some people up here I might start another thread and ask for local assistance for some compatibility testing down the road. :-)

    -Clay

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    That gravitron game would convert to laser display very well with a few minor changes. It looks great!

  10. #20
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    Quote Originally Posted by havok1919 View Post

    (I'm basically wondering if I can take my constant write-speed CRT vector display controller hardware and essentially just turn the 'draw/move' speed way down and use it with the laser. I suspect that it would always result in the scanner running a bit slower than it's potentially capable of since there wouldn't ever be any "move from A to B as fast as you can" type jumps, but I assume that the PID loop is running *much* faster than the point rate and a continuous signal wouldn't cause it issues?)

    Granted, I could just *try* this, but not knowing the conventional wisdom I'm trying to be a little cautious before I abuse anything *too* much. :-)

    Thanks again,
    -Clay
    Hi Clay, good to see some more game development here !
    Laser display is about showing as much detail with as few points as possible. If you use too many points your image will flicker, if you use too little points your image will be deformed by overshoots. So you will run into the challenge of optimizing the point placement along the beam's path to get as much detail out of the number of points that you can use. I might be able to help there when you arrive at that point.

    looking forward to your projects.

    Matthijs

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