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Thread: I-top dac and software Help?

  1. #21
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    DZurcher is absolutely correct on this one. Trust us on this one.

  2. #22
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    I made an pinouts for RGB. (QM2000 Pinouts)
    I use pin 1, 2 and 25 for the galvos and pin 5, 6, 7 and 25 for my RGB laser.
    Guess it is common setup
    Last edited by cruch; 03-31-2007 at 12:18.

  3. #23
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    Thanks for the backup on this issue carmangary! And good job on the image cruch. I guess it is understandable how some folks would mistake 18, 19 and 20 for where ground should be attached for thier lasers. And even potentially someone could mistake 14 and 15 for scanner common. But this is not the case. Pins 14 and 15 should only be used when using differential signals, in which case the scanner amp would specify +, ground and -. And pins 18 thru 23 are only used when the laser itself handles differential signals. In every case, pin 25 should be attached to all devices driven by the ILDA connector, differential or not. On pangolin, when your not using differential singals, pins 18-23 are all tied to pin 25.

    David
    Last edited by DZ; 03-31-2007 at 17:20.

  4. #24
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    Question Sorry for the hijack, but this brings up a question...

    Hmmm... I thought I had a pretty good understanding of the ILDA connector and how to wire everything up. But after reading your replies David, I'm starting to wonder if I've wired up my QM-32 adapter correctly... Maybe you can help.

    Like I said, I've got a QM-32 board. The pinouts are different; they're not wired to the ILDA standard like the QM-2000 board is. So I've had to build an adapter (using an rs-232 jumper box). I've downloaded the pinouts for the QM-32 connector as well as the ILDA standard. I've also picked up some extra information (both from the Pangolin site as well as from LaserFX.com) on how to wire everything up correctly. So here's the problem:

    The LaserFX site said that the three grounds on pins 4, 5, & 6 on the QM-32 projector connector are ANALOG grounds that should only be used with analog signals. Likewise, the 3 grounds on pins 23, 24, & 25 are DIGITAL grounds that should only be used with TTL signals. They made a point to warn you not to use a digital ground for an analog signal. (See the text at the bottom of the page on that link.)

    OK, so when I built my adapter, I connected the X out to X+, Y out to Y+ and then used one of the analog grounds to connect to the X- and Y- pins on the ILDA connector. I also connected one of the analog grounds to the RED-, GREEN-, and BLUE- pins. (R,G,B is an analog signal, after all, so they'd need an analog ground, right?)

    But if I read your post correctly, I should NOT connect the negative blannking lead from the laser to pins 18, 19, & 20 unless they support differential signals. Instead, I should connect it to pin 25, which is a DIGITAL ground.

    If I do that, I've got an analog signal connected to a digital ground, which is a no-no according to the LaserFX site.

    So which way should I go with it? (At the moment I don't have any blanking hooked up for fear of ruining something.)

    Adam

  5. #25
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    Hi Adam,

    I must be brief but... the adapter would be pretty simple. Something like this:

    QM32 Projector
    1 -------------- 1
    2 -------------- 2
    16 -------------- 3 (probably not needed)
    12 -------------- 5
    11 -------------- 6
    10 -------------- 7
    22 -------------- 13

    4 or 5 or 6 ---------- 14, 15, 16, 18, 19, 20, 21, 22, 23 and 25 (all tied together)

    That will do it. The only drawback is that you will only get half the width and half the height out of the scanners with this kind of adapter, since the QM32 did not supply differential output for X and Y. (Note that this is only the case if you are using differential input for X and Y on your projector, which may not necessarily the case.)

    Best regards,

    William Benner

  6. #26
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    Thumbs up

    Thanks Bill!

    Glad to know that there's no problem conencting the digital and analog grounds. (Wonder where they got that idea on LaserFX? Go figure!)

    And I see the other mistake I made - I forgot about the "Visible" signal... Of course! That should be connected to pin 3 for "intensity". (Which is very cool, because my monochrome green projector uses this pin for blanking.)

    I'm going to make the changes today. I want to see those shows with blanking!

    Again - thanks for the help!

    Adam

  7. #27
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    Hi Adam,

    A few things.

    First, I didn't use the digital ground. I only advised you to use pin 4 or 5 or 6, connected to all of those pins on the ILDA DB25. Digital ground on the QM32 is pin 25 if memory serves, but I could be mistaken. I designed that board back in 1992...

    Second, "visible" is a digital signal. If you have a single laser and it supports analog control (i.e. fading), I would recommend you use the RED or GREEN output, rather than the BLANKING output. Then you can train our color system such that all colors will be output to the RED and/or GREEN output. Hopefully the help file tells you how to do this. Unfortunately, there was no Tutorial DVD for the old LD/QM32 system...

    Bill

    PS: There is almost no difference between the analog and digital grounds. You could use them interchangeably with no noticable problems...

  8. #28
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    Talking Old Alphalite projector now running on QM-32! WOOT!

    Quote Originally Posted by Pangolin View Post
    First, I didn't use the digital ground. I only advised you to use pin 4 or 5 or 6, connected to all of those pins on the ILDA DB25. Digital ground on the QM32 is pin 25 if memory serves,
    Hi Bill,

    Yeah, my post was confusing. I was referring to the information from the LaserFX.com website (see link in above post, or click here) where they warned you not to use an analog ground on the QM-32 for a digital signal. Here is the text I was worried about:
    However, the analogue and digital grounds are different and separate grounds. Do not use an analogue ground with a digital signal, and vice versa.

    If I connected the analog ground (pin 4, 5, or 6) to pin 25 on the ILDA connector, that would be the only ground for the whole connector, which meant that any digital signal (including the "visible" signal we talked about) would be connected to an analog ground, in violation of the above information.

    This is what I was worried about, but after I read your post I saw that you had no problems mixing the two signals, so long as the analog ground was used. However, in my haste to reply, I didn't word my post very well - thus the "mixing grounds" confusion. My bad! But I did understand what you meant.
    Second, "visible" is a digital signal.
    This is OK, since the projector I'm currently using only supports TTL blanking, so the Visible signal is exactly the one I want. (In fact, the DB-25 plug on the projecor is wired to use pin 3 (the Intensity + signal) as blanking, so we're all set.)

    This is the projector that I used to run off my Alphalite, and Rick's standard for monochrome projectors is to use pin 3 for blanking rather than the individual color lines. Alphalite doesn't support analog blanking anyway, so there's no loss because you're still stuck with TTL. Also, up until recently it didn't have a way to output all colors to one color channel if you only had a monochrome projector. (It's been fixed now, but back when my projector was being built it wasn't an option in the software, so we had no choice but to use the intensity signal.)

    Anyway, earlier this afternoon I connected the analog ground from the QM-32 side to pin 25 of the ilda side of the jumper box, and also connected pin 16 on the QM-32 side (Visible) to pin 3 on the ilda side (Intensity). I plugged everything in, and Woot! It's working great!

    I played around with a few more files, and then I watched the star wars beamshow with the music and everything. No problems! (Well, I need to play around with the music sync a bit - it was a tad off.) But everything works like it's supposed to now.
    If you have a single laser and it supports analog control (i.e. fading), I would recommend you use the RED or GREEN output, rather than the BLANKING output. Then you can train our color system such that all colors will be output to the RED and/or GREEN output.
    Yeah, when I get an analog power supply for my other green laser I'm going to put it in a new projector housing that I've recently acquired. Then I'll add an analog red, and I'll wire the blanking to pins 5 and 7 on the ilda connector to get true analog color. (I'll probably need to wait a bit before I can add an analog blue to get full RGB though.)

    As for this projector, I think I'll keep it as TTL. (I'm in the process of adding red to it right now - should be done later this week.) But once I get the red laser in there, I'll switch the blanking leads over to the respective color signals so I can get RYG. Then I'll have to train the software to recognise the colors as you mentioned. (Time to dig into the help file some more!)

    Still, it was cool to finally get that projector running 100% on the QM-32 board. (Even if I'm about to rip it apart again...)
    PS: There is almost no difference between the analog and digital grounds. You could use them interchangeably with no noticable problems...
    Yeah, this is good to know. I don't know where they got that information on the LaserFX.com site, but it's clearly incorrect. But thanks for clearing it up for me! (Still, I'm glad I took my time - it would have sucked BIG TIME if I had blown something up!)

    Adam

  9. #29
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    Ground is ground. There is no such thing as an analog ground or a digital ground. Ground just means 0 reference voltage. All other voltages are respect to ground. It is called ground because it is usually connected to the ground in some fashion or another. If you go outside your house there is a wire stuck in the ground, most likely. If you connect your output to + and - instead of + and gnd then what happens is that your - becomes your reference. So instead of having a voltage variance from 0(gnd) to 5v, you have a variance from -5v to +5v. Your circuit doesn't see +5v, though. Circuits only care about the difference between common reference (gnd) and your your other voltage. But the difference between -5 and +5 is 10. So your components potentially have a 10v supply on them. If your components are designed to only handle 5v then that is very bad news. You've just overloaded them. That leads to double the expected current and power.

    As far as digital voltage and analog voltage goes... there is also no such thing. You could consider a signal to be digital or analog and there are components that are designed to work in the digital or analog world... but the voltage is standard EMF.

    Anyway, I strongly recommend learning these basics of electricty before willy nilly hooking things up.

  10. #30
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    Cool

    Carmangary;

    I appreciate your post, and rest assured I *do* understand the concept of a common ground in a circuit! Also, I really don't need a repeat of basic electrical theory; but thanks for looking out for my safety nonetheless.

    Now to the point, which you sort of captured, but then failed to follow through to it's logical conclusion. In an isolated circuit, ground can be wherever you want it to be. (Which you already mentioned.) For example, using a center-tapped transformer and a couple rectifiers, I can either use the center tap as a ground and get + and - voltages, or call the bottom tap ground and get two different positive voltages. The transformer isolates the whole circuit from ground, so downstream of it you can pick whichever point you want and call it ground. (Much the same as your example above.)

    But here's the key: if I don't actually *connect* that ground connection (whichever one I choose) to my house ground, it could very well end up floating above earth potential. I've experienced this several times. In fact, though it's normally not adviseable to do so, there are circuits that are *designed* to have a floating ground by default. (And yes, this fact has caused a few sparks to fly during some of my early experiments with electronics.)

    The warning on the LaserFX site made sense if you consider the possibility that the QM-32 might have completely isolated circuits for the differential output and the TTL outputs. (That's one way to ensure you can't have a ground loop! Though not the best way I'll admit.) Thus, the analog ground could actually be floating higher than the TTL ground, assuming neither one is tied to earth. In such a case, connecting the two might change the voltage offset on the differential circuit, causing problems.

    While I understand that this design would not be optimal (floating grounds being bad form and all), the warning had to be put there on the LAserFX site for a reason, and that was the only reason I could come up with. So now you understand why I wanted to be certain before I connected everything. (And I have to admit that my exaggerated choice of words: "afraid to blow something up" didn't add much humor to the post, and did make me sound like a clueless newbie. My apologies there.)

    Still, it appears that the information was not correct. Bill himself said that there wouldn't be a problem, although he didn't go so far as to say that they were tied together... He just said that you probably wouldn't notice the difference. That's good enough for me.
    As far as digital voltage and analog voltage goes... there is also no such thing. You could consider a signal to be digital or analog and there are components that are designed to work in the digital or analog world... but the voltage is standard EMF
    Huh? Whoa there... Now I'm starting to think that you might need to repeat a course in basic electrical theory. OK - I apologize.... That wasn't very nice. But there most certainly *IS* a difference between a digital voltage (which will not change, or at least will only change between two states - on and off) and an analog voltage, which can change to any level at any time.

    Perhaps you meant to say that the only difference between a TTL signal and an analog one is that there are more acceptable (that is, allowable) voltage levels in between the min and max when you're dealing with analog. (Whereas TTL has just two: +5 volts or nothing.)

    And I will grant you that a sufficiently rapid TTL signal will behave just like AC when it comes to reactive and inductive components in a circuit. But that's still a far cry from saying that DC = AC when it comes to voltage!

    For example, if we're talking about a TTL output that goes high and stays high for any significant length of time (longer than a 10th of a second, say), we can usually ignore the minimal capacitive resistance in the output circuit. Now, feed an analog signal at 2 mhz into the same output and see what effect any capacitance in the output has!

    Meh - we're getting off topic here, and I don't want to start a flame war over this. I'm happy that my QM-32 board is working, and I'm pleased that Bill resolved the question about the separation (or lack thereof) between the analog and digital outputs on the board. "Nuff said!

    Adam

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