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Thread: Ilda Buffer

  1. #1
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    Default Ilda Buffer

    Happy New Year to All!

    I'm looking for a proper ILDA buffer circuit scheme. (same like MAtilda from Stanwax) I can do the PCB so i don't wanna buy a P'n'P product.
    MY goal is buffering all of the signals @ projector's ILDA Thru ±,XY and RGB to feed the long and parallel cableing
    I have 2 FB3s and needed at least 2 x 120 meters daisychained (4x30 meters) ILDA cable . Too much for one FB3

    Greetings

    Ferenc
    Last edited by epyn; 01-06-2018 at 00:30.

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    Try drv137 to drv134. Just chips that do balanced to single and then back to balanced. Easy way to buffer instead of opamps on each line. Might as well do something in the middle while you are at it. At least level control.

    There are no external part other than the driver chips and some power supply coupling caps.

    Better way is optocouplers.

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    Oh if you want to flip axis see my Lorenz attractor schematic. I post an input that give unity gain unity negative inputs so you have no gain but can change polarity of the signal. Ie say flip over an image. Might as well buystanwax device. Cheaper smaller debugged

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    Using dedicated differential receivers/drivers would be a nice solution if you don't mind spending the money. Otherwise a simple set of 4-resistor single-op-amp diff amps will do the job at a lower cost and probably less board space, depending on what size passives you're comfortable with. Classic op amps like the TL07x/8x would be typical, but I try not to use anything that misbehaves outside its Vcm range. With a more modern rail-to-rail-ish op-amp the whole thing could run off of a common 12VDC wall wart with a suitable rail splitter giving +/-6V.

  5. #5
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    If you go look at this sticky, you'll find the old, original, ILDA recommended circuits. A lot of the DRV family designed for audio runs out of headroom when used for ILDA standard signals, so choose your chips carefully..
    ~
    https://www.photonlexicon.com/forums...ILDA-STANDARDS
    ~
    Steve
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    Nothing there but your letter.

    The drv 134/7 worked fine for me even on 9v batteries. Was going to use 15v but didn’t need it.
    Still is expensive but really easy to use. I like stanwaxs stuff he makes good boards.

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    Thanks for the ideas!
    I thought i'm going to use simple voltage follower circuit as buffer for each channel.
    I'm confused about the opamp.

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    Quote Originally Posted by epyn View Post
    Thanks for the ideas!
    I thought i'm going to use simple voltage follower circuit as buffer for each channel.
    I'm confused about the opamp.
    Same thing. Simple non inverting opamp on each line. So one for x+ one for x- etc....nothing fancy.
    match impedance so I think 47k resistors and like 22pf bypass caps on feed back loop. Usual 0.1uf caps on chips. I add 10uf in parellel too but not needed...chip power bypass I mean. for clarity.

    http://www.electronics-tutorials.ws/opamp/opamp_3.html

    voltage follower is good too. I usually like to add gain or cut. That’s why the arrangement I used allows both unity cut and unity boost. Handy. Might as well do something if you go to the trouble of adding opamps. You could also do it with single transistors.

    - - - Updated - - -

    On point on voltage followers. Make sure to have rail headroom. Same point steve made.

  9. #9
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    Kecked et Al,

    Scroll down to the last two pages of the PDF linked in the sticky, there is MORE then the letter in the header... The sticky is at the top of Shows, Displays, and Scanning in the Forum... Along with two other interesting ILDA documents from the Beginning of Time..

    I attached it here, again

    Steve
    Attached Thumbnails Attached Thumbnails ILDA-CONNECTOR1.pdf  

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  10. #10
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    Note that using differential receivers and transmitters has the advantage of rebalancing the outputs with respect to ground. Unity gain buffers on each line will simply (effectively) cut the cable impedance down. If for some reason the signals diverge from the ground reference over the length of the cable run it's possible that the projector's common mode input range will be violated. In the worst case, where op amps like the TLO7/8 series are used in the projector's input, this can result the output slamming to the opposite rail, which is generally....unkind to galvos. Effective modulation signals, if single-ended and with the negative sides tied to ground, will drift up or down with ground offset as well. It's probably not a concern on projectors with reasonably designed inputs over reasonable cable runs in reasonable conditions, but if you're already building a buffer, it's a nice feature to have.

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