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Thread: colorsignal, single ended or differential

  1. #11
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    My opinion - reseiver's input will better differential:
    - with "single ended" signal (most controllers use this type now...) it will work same as "single line" receiver;
    - but when you connect to controllers with "differential" output BY LONG CABLE - you will have clear and full-volume signal (in different to single-ended connection...)

    Type connection will be moree important for coordinates... not for colors...
    But it is question to standard...

  2. #12
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    The ILDA standard calls for differential but allows for single ended, if the single ended sender has enough swing to drive the differential receiver with one input grounded. The ILDA standard gives an example of preferred line receiver circuits.

    It is possible to make a receiver circuit that can do both.

    QM2000 can still do differential color with one resistor removed per channel on the QM2000. Pangolin simply loads the negative drive with a small resistor.

    I have arranged for the core technical part of the ILDA standards to be on the PL as a sticky.

    Worth a read. Keep in mind its a 20 year old document.

    See the ILDA-CONNECTOR PDF, one of three stickied at the top of Laser Shows and Scanning...

    http://www.photonlexicon.com/forums/...ILDA-STANDARDS


    We got away from the standard because one particular maker of popular diode drivers used zero to five.
    So did one maker of DPSS.. The rest is history.

    Its wise to add protection on your input circuits to allow accidental reverse polarity connection and to have clamping above 12 volts. Please design the clamping as to not destroy the signal source by limiting current flow. The cost to do so is about 2 to 5 Dollars.

    QUOTING THE ILDA STANDARD:

    " A variable gain control to compensate for variations in source
    voltage levels and line loading effects is recommended but not required."

    Which is why good diode drivers and high end projectors have a input potentiometer for each color channel. Really good projectors have X-Y size knobs on the back too, but that is a discussion for another day.


    Steve
    Last edited by mixedgas; 09-18-2014 at 05:21.
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  3. #13
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    Thanks mixedgas.

    When the ILDA standard was created i can see that it was made to be perfect. But it seems that some manufactures have taken a shortcut...... I agree with Riya that differential is the right way to do things so there is less chance of distortion of any kind. Because having differential input on a driver is a mather of a few dollars i don,t see any reason to have not an input that can do both.

    Thanks for the info guys :-)


    Interested in 6-12W RGB projectors with low divergence? Contact me by PM!

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