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Thread: 1x ilda in - 5x ilda out - help

  1. #11
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    A few weeks ago I dug out a 4 way switch box I was gonna give to cruch, but I think he's got one sorted now. So whats to stop me from rewiring the box to a fixed 1 in - 4 out?
    Why is an op-amp needed? What does it do, how and why?

    Ta,
    Dan

  2. #12
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    Every time you split the signal, it gets weaker. In the case of laser scanners, this would mean you wouldn't get full power from your analog lasers, and you would get a reduced scan angle.

    The opamps take the signal from your DAC, and basically add power to it, so it can be split up without loss in power.

    It's pretty much like an audio amplifier, although a little less complicated

  3. #13
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    Quote Originally Posted by ElektroFreak View Post
    OK. So based on that, couldn't you just put a drlava correction amp board in each projector or several together in some sort of a splitter box? Wouldn't that accomplish the same thing?
    Yes, you could, with some creative resistor value changes, but I believe that board inverts, and you'd need 1 of them for every 4 functions as they are single ended.

    Steve
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    Hmm. Alright, so this might work. I'm curious as to why I'd need one for every four function instead of one for every six? When it's utilized with a sound card DAC it provides six channels of amplification. Why would this not remain the case here as well?

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    Quote Originally Posted by ElektroFreak View Post
    Hmm. Alright, so this might work. I'm curious as to why I'd need one for every four function instead of one for every six? When it's utilized with a sound card DAC it provides six channels of amplification. Why would this not remain the case here as well?
    My correction card is 8 channel, you need two correction card channels to buffer each ILDA differntial pair. So you have three functions with a six channel card and 4 with 8 channel card. Unless you like single ended signals with long cables, which kind of defeats the point of using the ILDA standard and a buffer/splitter box. remember, ilda signals are two wire differntial pairs. The correction cards are single ended (one wire with a common ground wire), so you need two slots on each card to make one ilda two wire pair.

    Steve
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    You must have a more recent version of the correction amp than I do.. Mine has inputs for X,Y,R,G,B,I and that's all (plus ground connections for all of them).. and offset and gain pots for each. EDIT.. after reading your addition, I think I'm getting it. Let me ponder this for a bit. I may have more questions yet.. Thanks for all your help so far Steve..
    Last edited by ElektroFreak; 07-02-2009 at 10:42.

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    Ok, if you run a signal on a single unshielded wire in a electromagnetic field it picks up interference and there is nothing you can do about it. This wire is referenced to ground.

    If you run two wires, one with a mirror image of the master signal on it, ie inverted, the noise will be the same on both wires, but signal A, when you look at it, will in math be A+ N where a = signal and N = noise, and the signal on wire B will be -A+N when you electronically subtract these from each other in the receiver circuit you get A+B,and 1/2N, cutting the noise by half or more. Toss in a grounded shield in the ilda cable you get a very low noise signal.

    So for each wire in the ilda cable, we need 2 channels of Andrews board , one for +A and one for -A. On a 6 channel board that means we only get to buffer 3 signals.

    http://en.wikipedia.org/wiki/Differential_signaling

    Steve
    Last edited by mixedgas; 07-02-2009 at 14:39.
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    Quote Originally Posted by mixedgas View Post
    Ok, if you run a signal on a single unshielded wire in a electromagnetic field it picks up interference and there is nothing you can do about it. This wire is referenced to ground.

    If you run two wires, one with a mirror image of the master signal on it, ie inverted, the noise will be the same on both wires, but signal A, when you look at it, will in math be A+ N where a = signal and N = noise, and the signal on wire B will be -A+N when you electronically subtract these from each other in the receiver circuit you get A+B,and 1/2N, cutting the noise by half or more. Toss in a grounded shield in the ilda cable you get a very low noise signal.

    So for each wire in the ilda cable, we need 2 channels of Andrews board , one for +A and one for -A. On a 6 channel board that means we only get to buffer 3 signals.

    http://en.wikipedia.org/wiki/Differential_signaling

    Steve

    I see what you're saying. Two boards for a complete XYRGBI signal. Makes sense, I just never considered that it was done that way.

    I really have limited experience with the homebrew DAC aspect of scanners, as up until recently I was only using DMX. Then I decided to build a soundcard DAC and I've been able to get pretty stunning results using it. I know there are better options out there, but none in the same price bracket. I've been mulling over ways to run more than one scanner off the same signal, but I wasn't sure if I could just use another correction amp for this or not. I definitely appreciate you taking the time to lay it all out. Very good info so far!

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    For 20 minutes in that Helo in your Icon, I'll train you in anything you want to know.

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  10. #20
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    so whos gona make some of these and sell em to forum members??
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