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Thread: Compact/alternative ILDA connectors - Thoughts

  1. #1
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    Default Compact/alternative ILDA connectors - Thoughts

    I've been looking for a more compact alternative for the standard ILDA (DB-25) connectors, which are bulky and (relatively) expensive when you need longer cable runs.

    Most projector housings already have a couple of Neutrik D-sized holes populated with 3-pin XLR for DMX input, and I was looking for a connector that would fit this form factor so it is also more robust in on-the-road setups.

    Since we're mostly using 5 wire pairs for X/Y/R/G/B, ideally you'd need a 11- or 13-pin connector (if you also want to carry DMX on the same cable), however, Neutrik doesn't stock any connectors in the size with more pins than 8.

    Neutrik Ethercon and standard CAT5 cables are an option, but the tradeoff is that you need to run single-ended signals for R/G/B modulation, possibly introducing noise. Advantage would be that it's easy to convert to Ethernet in the future, and CAT5/CAT6 cables are insanely cheap (and often even free) to get almost everywhere.

    "VGA" HD-15's would be an option, they are compact and cheap, but they are just as fragile, if not more fragile, than DB-25. DB-15 could be a useful alternative, but it only saves marginally on compactness.

    Best case would be a (locking) connector that has at least 15 pins, for differential X/Y/R/G/B wire pairs, and an additional pair for both DMX and emergency stop/interlock. Any compact form factor would be useful for it, but circulars are probably most beneficial since they're easiest to handle and install on the road. AMP CPC may be a good option here - they are locking and robust (people familiar with argon heads should know), but are more expensive and AFAIK, not all AMP connectors allow cables to be connected in-line.

    Obviously, for connecting to the DAC and for ILDA projectors that need more colours you could still use DB-25 and mix/match using adaptor plugs. Beam table effects (like gratings or lumia) are just as easily done through DMX with some standard relay boards.

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    CPC connectors are a good option but painfully expensive (housings and pins)

    try RJ45... balanced XY and single ended RGB and see what happens... most lasers are single ended input anyway

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    RJ45 or Ethercons (which are just RJ45 in a locking XLR-like shell) are an inexpensive option, but they have a few drawbacks: First off, you will still need an extra cable for your emergency stop AND your DMX connections. Secondly, RJ45 has no idea of connector gender, so you would need couplers to extend your cables if you run short (couplers could be fragile and prone to get lost) and it's possible to hard-wire multiple outputs togethers accidentally. XLR and CPC have cable mount sockets which leave no room for confusion or mis-plugging.

    My goal would be to have a single cable assembly I can run to all of the projectors I intend to run off a single ILDA link, with no additional cables to attach aside from possible power I/O.

    RJ45/CAT6 cables would be ideal for (galvanically separated) digital interconnects with active repeaters downstream, however.

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    If you want it to be close to a DMX sized plug, look at Hirose. However the wire is expensive, and forget quick repairs.

    Ilda thought long and hard before choosing DB25, 37 pin CPCs were what was first used. CPCs are nice when you can replace a male or female pin in about 2 minutes. The glass reinforced plastic works well in the field, and is sort of self cleaning. If you want to make a extender, reverse sex and mirror CPCs do exist for most sizes.

    What drove the DB25 was the ease of getting multi-position printer and serial switchboxes, you could toggle from ADAT to Pangolin to Abstract console with a switch that cost just 15$-25$

    If you want compact and reliable, the video and instrument guys use either Cannon or Tyco-Amphenol mil spec plugs or Hirose connectors. The initial sticker shock is not that bad, but the time to solder them up is.

    mini-15-DB VGA is a real pain in the neck to solder, and they are fragile.

    That leaves MOLEX, and if your going to use Molex, you had best buy the pin replacement tool first thing, or make up a adapter board from ILDA to PCB mounted molex. Besides, the Molexs with strain reliefs cost almost as much as the CPCs.


    The first, now long superceded ILDA spec calls for a wire with the same impedance and capacitance per foot as Belden wire types: 9731,9734, or 9735 or Manhatten Wire type M13115. The first, but not used for long, ILDA connector was a CPC style 1 Shell Size 23 with part number 206306-1 for the chassis mount and 206305 for the cable ends, using 66103-2 and 66105-2 pins in tin, or 66103-4 and 66105 gold plated pins. The cable clamp was a 207774 or a 206512-1.

    I'd scan in the ancient ILDA standards and their suggested practices, circuits, and impedances, but I'd want to hear from Tim Walsh or Pat Murphy that it was Ok. It would explain to many newer folks why a lot of older folks chose to do what they did, and why it was a "Good Thing". Its upwards of 100 pages, double sided.

    KEEP in mind the CPC was surpassed by the DB25, I'm just mentioning it because it was already in place at one time and could handle two RGB heads with fully differential color and a shutter, plus still have spare wires.

    A non analog ILDA standard cable was possibly in the works. However the prime mover in the project passed on.

    Somebody in Europe was selling ILDA to Cat-5 boards a while back, but it turned out to be a FAD. There were problems with dirty contacts etc. Keep in mind, that unless you actually flow substantial currents in a cable to keep tin pins self cleaning, you want a large surface area, not a tiny wire like the RJ plugs on cat-5

    Of course, 37 pin solder cup DBs do exist, used to be quite common, and would handle 2 projectors.

    Cheap Cat-5 is hard, solid wire, and does not like repetitive motion, meaning you need to pay extra for the rubberized, stranded, flex cord, if you want it to last.



    Steve
    Last edited by mixedgas; 08-13-2011 at 13:54.

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    Quote:

    Belden 1279p = 5 mini coax's. https://edeskv2.belden.com/Products/...il&partid=3048

    End Quote.

    Five mini coax = half the possible cable distance and no way to eliminate ground loops, no shutter, safety loop, or serial lines, which some of us do use, do use and legally need. Otherwise, nice try.

    Steve

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    Just stick your DAC in the projector and run Ethernet.

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    Quote Originally Posted by j4cbo View Post
    Just stick your DAC in the projector and run Ethernet.
    That's kind of missing the point and moving the problem to another OSI layer (from L1 to somewhere in L4 upwards). Ethernet is NOT fail-safe and therefore you still need to run a separate cable or conduct some seriously out-of-spec hacks to use Ethernet safely and securely. Your statement is like: "So you have too much stuff to fit in your Toyota Aygo at once, and you need a solution to move house? OK, here's the deal: Just buy yourself a truck."

    I am looking for a decent physical replacement for the ILDA connectors. Sure, moving the DAC around would be a good concept, but if I were to do so, there are other routes which could be more beneficial than Ethernet, which is not designed for real-time vector graphics and safety-critical data.

    I have some digitized 'ILDA' protocol drafted up, along with a few simple prototype designs, but don't have the means to work them out yet. It's beyond the scope of this discussion for now.

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    How about HDMI? 19 pins - shielded twisted pairs - Small connector - cheap cables?

    /Thomas

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    Quote Originally Posted by Badpip View Post
    How about HDMI? 19 pins - shielded twisted pairs - Small connector - cheap cables?

    /Thomas
    Impossible to solder (surface mount), and have you ever tried to order HDMI cables on a 100-foot reel? Those cables cost a fortune.

    Also, HDMI is not locking so prone to falling out of its socket, and it has the same problem as RJ45: No in-line cable extension possible.

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