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Thread: Projector woes

  1. #1
    Join Date
    Jun 2011
    Posts
    2

    Default Projector woes

    Hi all!

    I was able to get my first laser scanner running today.

    It uses a correction amp on a breadboard connected to a Best Connectivity SD-AUD20040 USB sound card which uses the Cmedia CM6206. They are connected to a SpaceLas PT-30K scanner unit.

    I have been using LFI software to display a few .ild ILDA files that I have been able to grab from various links I've come across on this site.

    At first I had some issues with wobbly output, but through trial and error adjusting various settings bars in LFI, I have so far been able to get surprisingly good looking, stable, and sharp images. I find that even on the "good" image files I have to change the points-per-second setting in order to find a value that cancels out what I like to refer to as "wobbling" - sub-sections of the image wobble up and down periodically and slowly, making the image unbalanced most of the time.

    But, there are several ILDA test files which have many circles and letters and things like that, and I get a pretty messed up image from the projector. It seems to want to move diagonally to another location when it is blanking (or something like that)... I will take a picture and post it up in an edit. I am wondering what sort of things I can do to figure out what's going on with these?

    Another issue I am trying to figure out is what values to tune the amplifier for. My scanner takes 6 input lines, +X, -X, GND, +Y, -Y, GND, yet my soundcard dac produces a single signal line. I have tried connecting 0V to -X and signal (with gain set to 6.5V at max) to +X and it seems to work but I want to know how I am supposed to set it up so as to get maximum scan angle.

    I am also unsure about what this scanner is supposed to accept in terms of voltages. On this site I saw that +X and -X (and the Y's) are differential signals that don't seem to exceed a magnitude of 5V each. But the DAC amplifier doesn't produce anything like this. Is it safe for me to swing to +10V?

    Any advice or help not directly related to my questions would also be helpful!

    Thanks.

  2. #2
    Join Date
    Apr 2010
    Location
    Grand Rapids, Mi
    Posts
    2,495

    Default

    Did you short the caps on the soundcard? Who's design for the correction board have you used?

    Quote Originally Posted by arcaneinsomniac View Post
    Hi all!

    I was able to get my first laser scanner running today.

    It uses a correction amp on a breadboard connected to a Best Connectivity SD-AUD20040 USB sound card which uses the Cmedia CM6206. They are connected to a SpaceLas PT-30K scanner unit.

    I have been using LFI software to display a few .ild ILDA files that I have been able to grab from various links I've come across on this site.

    At first I had some issues with wobbly output, but through trial and error adjusting various settings bars in LFI, I have so far been able to get surprisingly good looking, stable, and sharp images. I find that even on the "good" image files I have to change the points-per-second setting in order to find a value that cancels out what I like to refer to as "wobbling" - sub-sections of the image wobble up and down periodically and slowly, making the image unbalanced most of the time.

    But, there are several ILDA test files which have many circles and letters and things like that, and I get a pretty messed up image from the projector. It seems to want to move diagonally to another location when it is blanking (or something like that)... I will take a picture and post it up in an edit. I am wondering what sort of things I can do to figure out what's going on with these?

    Another issue I am trying to figure out is what values to tune the amplifier for. My scanner takes 6 input lines, +X, -X, GND, +Y, -Y, GND, yet my soundcard dac produces a single signal line. I have tried connecting 0V to -X and signal (with gain set to 6.5V at max) to +X and it seems to work but I want to know how I am supposed to set it up so as to get maximum scan angle.

    I am also unsure about what this scanner is supposed to accept in terms of voltages. On this site I saw that +X and -X (and the Y's) are differential signals that don't seem to exceed a magnitude of 5V each. But the DAC amplifier doesn't produce anything like this. Is it safe for me to swing to +10V?

    Any advice or help not directly related to my questions would also be helpful!

    Thanks.
    leading in trailing technology

  3. #3
    Join Date
    Apr 2010
    Location
    Grand Rapids, Mi
    Posts
    2,495

    Default

    And who are you where are frfom etc, etc welcome but tell us about yourself and fill out your profile...

    And to answer your question I run mine between +X and -X +5v and -5v is a difference of 10v
    leading in trailing technology

  4. #4
    Join Date
    Jun 2011
    Posts
    2

    Default

    Ah, I have been a lurker for so long I hadn't realized this is my very first post.

    Well I am in northeastern Massachusetts. Just got out of college, I studied computer science.

    I have bypassed the caps on the sound card and I am fairly certain I did that part correctly. Could you elaborate on what you mean by +5V and -5V? Is your projector ground connected to the ground of any other component (computer, soundcard, amp)? Currently I have it set up so the only wires connecting the scanner and the rest of the equipment are the +X,-X,+Y, and -Y lines.

    I was setting it up before where I connected +5V (the correction amp's power line) to -X and then tuning using max.wav to give +10V (on +X), so zero volume yields 0V (on +X). That makes the -5V to +5V differential range but I never see LFI "making use" of the full range with this. Meaning when I play and pause max.wav, the dot will swing diagonally a good 30 degrees, yet when I run LFI the image never covers more than 15 degrees or so.

    I'm thinking about writing some programs using EzAudDac.dll and testing from there because I feel like the software is the biggest limitation so far, but I'd like somebody to tell me what is supposed to be fed into the voltage input for the galvos. I really don't wanna fry them.

    Oh, and happy Turkey Day!

    One more thing. I definitely need to do more testing and write down notes while I experiment, but I recall the galvo's (and the mounting block which serves as a heatsink) heating up significantly when I had the +5V hooked up to -X and -Y. The signal seemed to work but I never had it heat up quite that much when I went back to GND on -X and -Y.
    Last edited by arcaneinsomniac; 11-24-2011 at 15:01.

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