Thoughts on this light... World's smallest RGB DMX light

SanTai

Active Member
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Dec 24, 2010
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Sweden
I've got another possible solution to suggest:

Since you are already supplying power too the xlr/trs adapter, you could with a few resistors impedance match the different kinds of cable which will adress the problem mentioned here about reflections. However this will comes at a cost, it will lower the signal level but that could be addressed with a simple amplifier since you've got power.

Please not that this will not solve the high characteristic capacitance problem that could be that case with audio cable, that could be solved with recommending a specific cable that meets that criteria.


This way of doing it is not following the standard, but done right it would avoid all that which you want to avoid with following the standard.
 
Joined
Jul 30, 2011
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I've got another possible solution to suggest:

Since you are already supplying power too the xlr/trs adapter, you could with a few resistors impedance match the different kinds of cable which will adress the problem mentioned here about reflections. However this will comes at a cost, it will lower the signal level but that could be addressed with a simple amplifier since you've got power.

Please not that this will not solve the high characteristic capacitance problem that could be that case with audio cable, that could be solved with recommending a specific cable that meets that criteria.


This way of doing it is not following the standard, but done right it would avoid all that which you want to avoid with following the standard.
I was wondering when a page 2 would be started for this thread --- it was take quite a white to load the first page, lol =)

After looking at all the possible suggestions here, we will be prototyping a cable with a PCB attached to the end with 2 RJ45 ports (DMX in and DMX out) and a 12V DC in. There will be 2 added items to the PCB: an LED power indicator and a switch to connect or disconnect a 120ohm resistor for line termination. I'll keep everyone posted on the progress --- I hope this solution (although it may not look as nice as the smaller TRS connectors) will make everyone more at ease with our product configuration. Please let us know otherwise, if this configuration still does not follow DMX512 standards.
 

DuckJordan

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Doesnt matter
It sound great and actually as long as your trying to require users to use a data rated cable its within guidelines to me. Personally I'd much rather see an RJ45 than a TRS for dmx control. Also the Idea of adding a switchable termination on the devices makes it a convenient device. If I had the budget I'd probably purchase a set of 20 of these new models.
 
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I think it's great how thrilltainment is actively listening to the suggestions posted here, rather than endlessly defending his product. He could easily claim that it's "just fine the way it is". This is how great products are developed --- by listening to customers/potential users.
this forum has certainly offered us a lot of insight --- us engineers often need to take a step back and look at the big picture of the application instead of just the product itself. thanks for your appreciation =)
 

xander

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Joined
Dec 16, 2008
Location
New York, NY
After looking at all the possible suggestions here, we will be prototyping a cable with a PCB attached to the end with 2 RJ45 ports (DMX in and DMX out) and a 12V DC in. There will be 2 added items to the PCB: an LED power indicator and a switch to connect or disconnect a 120ohm resistor for line termination. I'll keep everyone posted on the progress --- I hope this solution (although it may not look as nice as the smaller TRS connectors) will make everyone more at ease with our product configuration. Please let us know otherwise, if this configuration still does not follow DMX512 standards.
Personally, I do not think RJ45 connectors are the right choice if you are planning on marketing the product to the theater/event industry. If you are only marketing to the architectural sector, then I would say "ok". My concerns are as follows: The use of category cable for data transmission is only compliant with ANSI E1.11 - 2008 if the cable is run in a conduit or similar to provide shielding. As I said, for permanent installs, I think this is fine because the standard is much more likely to be followed. However, for the more temporary industry, by providing only RJ45 receptacles, the likelihood of consumers using Radio Shack "ethernet" cables soars. I would say Ethercon connectors, perhaps? But then you are at the same form factor as a XLR5, and then the question becomes why not just use that?

Because I don't have the smarts to come up with some brand new brilliant idea about how to solve this, I think maybe the best way to approach this would be to take a play from Color Kinetics and use the XLR4. Add a tail to the instrument so that the connector doesn't interfere with its size. Yes, daisy chaining is nicer, but the ColorBlasts aren't having any trouble selling. Make it compatible with existing accessory PSUs (e.g. ChromaQ, Rosco, DFD, etc.), and there ya go. People already have all the necessary infrastructure to pop these right into their inventory.

But I am just thinking out loud.

-Tim
 

shiben

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Joined
Jun 25, 2009
Location
Chicago, IL
Personally, I do not think RJ45 connectors are the right choice if you are planning on marketing the product to the theater/event industry. If you are only marketing to the architectural sector, then I would say "ok". My concerns are as follows: The use of category cable for data transmission is only compliant with ANSI E1.11 - 2008 if the cable is run in a conduit or similar to provide shielding. As I said, for permanent installs, I think this is fine because the standard is much more likely to be followed. However, for the more temporary industry, by providing only RJ45 receptacles, the likelihood of consumers using Radio Shack "ethernet" cables soars. I would say Ethercon connectors, perhaps? But then you are at the same form factor as a XLR5, and then the question becomes why not just use that?

Because I don't have the smarts to come up with some brand new brilliant idea about how to solve this, I think maybe the best way to approach this would be to take a play from Color Kinetics and use the XLR4. Add a tail to the instrument so that the connector doesn't interfere with its size. Yes, daisy chaining is nicer, but the ColorBlasts aren't having any trouble selling. Make it compatible with existing accessory PSUs (e.g. ChromaQ, Rosco, DFD, etc.), and there ya go. People already have all the necessary infrastructure to pop these right into their inventory.

But I am just thinking out loud.

-Tim
Actually thats a really good idea. Then the consumer wouldnt have to buy new cables, and your power and data is all taken care of... Only issue I can think of is you really will want a daisy chain function of some sort on there, and also thinking out loud, If I wanted to put 20 of these near each other, thats a ton of cable and XLR connectors that I now need to tape up/deal with...
 

gafftapegreenia

CBMod
CB Mods
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Sep 24, 2005
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Michigan
Xander, thats essentially what I was trying to get at. Go with a tried and true format. If it had a single power supply with 5 pin XLR for DMX in and out that could power say, a dozen of these little fixtures with a single cable to each fixture, I think it'd be great.
 
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The XLR 4 format seems feasible because of the combination of power and signal. Does anyone know the specifications of the signals in the XLR4 cable? Is it simply passing the XLR5's data DMX + and DMX - to the XLR4 wire or does some processing occur?

If anyone has one of these Chroma Q power supplies and wouldn't mind testing for connectivity between XLR5's pins 1/2/3 and the XLR4 pins 1/2/3 I would greatly appreciate it.

Excuse the crude drawing again, but how would everyone feel about this type of cable assembly?



This will most likely have to be a complete revision of the fixture because it is a 24V system.
 

soundlight

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Oct 27, 2005
Location
NJ & NYC
I still like the daisy chain idea. If you look inside a lot of DMX fixtures they're just taking a tap off of the line as these do with the split cable. I do like the idea of a more industry standard connector, though. I don't like the part about a mini TRS not being locking. That could be a real issue. I do like the part about carrying power on the line. I think that with RJ45 you would be able to carry power and data on the line for a certain number of these fixtures (12? 20? 30? Depends on power draw.) and make the cable runs much easier if there were a bunch in a row. I absolutely despise that the CB12s require a home run per fixture. They still sell because they were the right product in the right place at the right time, not at all because they're the best tool for the job. Home runs on those things can really suck.

So - RJ45, daisy chain, carrying power + data. Not exactly sure how you'd do it with the size of the fixture (which I do think is wonderful) but this is something to consider, I think.
 
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This hits the same snag as your original design with the wye-ing of the data cable.
like soundlight has mentioned, most DMX fixtures ARE simply tapping into the main line. They simply do it within the fixture where we have a cable doing it outside of the fixture. The non-compliant Y that should worry people are ones where you have multiple fixtures hanging off of each branch of the Y --- and over longer distances. The Y split here is only at most 20 inches long and dedicated to a single receiver. If you think about it, just about every single pass-thru DMX unit is a mini-Y split.
 

beardedbil

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Jul 8, 2010
Location
New York
Hey Quan,
I hope my original post has helped and not thrown you for a loop. I only want to see your products get better and have more uses for more venues. I to enjoy that you are on here and actually listening to the needs of possible users. If there is a revision to the light I hope to run it for a test drive some day.

I do like the idea of running power and data over the same line (XLR4), makes my life easier when installing... not sure if its possible or practical though...
Best,
Bill Rod.
Dark Tech Effects
DARK TECH EFFECTS
 
Last edited:
Joined
Jul 30, 2011
Location
Santa Clarita, CA
I still like the daisy chain idea. If you look inside a lot of DMX fixtures they're just taking a tap off of the line as these do with the split cable. I do like the idea of a more industry standard connector, though. I don't like the part about a mini TRS not being locking. That could be a real issue. I do like the part about carrying power on the line. I think that with RJ45 you would be able to carry power and data on the line for a certain number of these fixtures (12? 20? 30? Depends on power draw.) and make the cable runs much easier if there were a bunch in a row. I absolutely despise that the CB12s require a home run per fixture. They still sell because they were the right product in the right place at the right time, not at all because they're the best tool for the job. Home runs on those things can really suck.

So - RJ45, daisy chain, carrying power + data. Not exactly sure how you'd do it with the size of the fixture (which I do think is wonderful) but this is something to consider, I think.

the problem with RJ45 carrying power is that the wires are simply too thin. Although there are Power over Ethernet solutions (PoE), they require 48 volts running at most at 350mA over 2 pairs of wires. (pins 4 and 5 positive, pins 7 and 8 ground). That's a max of ~16Watts ---- not much power even for these small fixtures, you can run only 5 at most, plus all the added circuitry to lower the voltage.

XLR4 has the specifications for more current through the cables.
 
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Hey Quan,
I hope my original post has helped and not thrown you for a loop. I only want to see your products get better and have more uses for more venues. I to enjoy that you are on here and actually listening to the needs of possible users. If there is a revision to the light I hope to run it for a test drive some day.

I do like the idea of running power and data over the same line, makes my life easier when installing... not sure if its possible or practical though...
Best,
Bill Rod.
Dark Tech Effects
DARK TECH EFFECTS

Thanks for checking in Bill =)

It's quite interesting because our product pertains to multiple industries. We started out with haunted attraction lighting where they simply need 12V and plug and play features. Most haunted attractions don't really need all the complex controls of theatrical lighting, they just set them to a certain setting and leave it (for the most part). Cost is also another issue for them --- many of them build their own LED fixtures for a few dollars, so making a product that's nearing $100 is already on the high end for haunted attractions.

This forum has brought insight from a completely different industry that requires higher end products and are probably willing to pay more for it as fixtures in this industry can range from a few hundred to several thousand a piece. I believe the input here has given us a lot of ideas for future products that will cater to the professional theatrical lighting industry --- probably with higher powered outputs as well. We'll probably come out with a pro series in the near future that will keep the innovative edge but also bring in features that can cater to more industrial situations.

- Quan
 

xander

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Dec 16, 2008
Location
New York, NY
like soundlight has mentioned, most DMX fixtures ARE simply tapping into the main line. They simply do it within the fixture where we have a cable doing it outside of the fixture. The non-compliant Y that should worry people are ones where you have multiple fixtures hanging off of each branch of the Y --- and over longer distances. The Y split here is only at most 20 inches long and dedicated to a single receiver. If you think about it, just about every single pass-thru DMX unit is a mini-Y split.
I know this. However, in instruments, the tapped leg is usually shorter, say like 8". Is there a big difference between 8" and 20"? I don't know. Probably not. I'm not an expert. But figuring that out should be a priority.
 
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I know this. However, in instruments, the tapped leg is usually shorter, say like 8". Is there a big difference between 8" and 20"? I don't know. Probably not. I'm not an expert. But figuring that out should be a priority.
This difference is insignificant. People only worry about reflections when the cable is several hundred feet long or more --- a difference of 12" per fixture x at most 32 fixtures per universe is only adding at most 32 feet into the entire system, which is likely to be an order of magnitude longer. W can build in a switch that connects a terminating resistor onto the line and be user selectable if found necessary.

This is also experimentally verified, we had as many as 64 fixtures on a universe using our current fixtures with TRS extensions, the cable was unshielded, put in loops, and run over 900ft long, if you count the "Y" legs, that's another 64ft of potentially un-kosher cabling. The proposal with XLR4 will be using shielded cable with the proper impedance which should work just as well, if not better.

I guess to completely satisfy your worry, such a fixture would need a terminated signal repeater built into it. However, that also means if there is no power to this particular fixture, the subsequent systems will not be receiving DMX signal.
 

Beans45601

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Jan 18, 2010
Location
Southern US
I think it's great how thrilltainment is actively listening to the suggestions posted here, rather than endlessly defending his product. He could easily claim that it's "just fine the way it is". This is how great products are developed --- by listening to customers/potential users.
I agree. This is wonderful to see, thanks!
 
Joined
Jan 5, 2009
If I remember correctly the documentation I read said that the 'Y' branch inside the fixture could be up to about a meter (3 feet), so a 20" 'Y' branchof per fixture would be acceptable.

As far as the plug you are choosing goes, I hope that the initial conversion unit where you receive the DMX signal and put the power on the line will feature normal XLR5 plugs (IN and THRU and that the unit will basically be a buffer/splitter so that the 'branch' of LEDs is isolated and if the main-bus uses the second pair (I forget what mode it was called but basically you can use the second pair so that you can use the DMX-line in full-duplex as of E1.11-2004 optionally) that won't be interfered with by the LED branch only using the main pair.
The design with the simple M-F XLR4 is really nice and compact which I think fits your bill exactly.

Also if your units are good enough and present a low enough load to the signal you'll be able to fit more than 32 on one line, as far as I understand quality transceivers these days present about a quarter of the 'units of load' that are defined for EIA-485.
 

thesigma

Member
Joined
Feb 25, 2008
Keep in mind that the XLR-4 is commonly used in the video industry as a power connector for 12VDC, so you may wish to stick with the standard pinning for those which I believe is pin 1 ground and pin 4 +12V. I assume you would then be using pin one also for the DMX line Shield? or will it be unshielded, which in theory should be fine. Personally I would use an RJ 45 for power and data ala PoE, use the same pins for power as PoE and require a home run for each light, back to a splitter box that actively splits out to the lights and accepts a XLR-5 in and thru for standard DMX lines. Does this push cost up...well yes some. however cat 5 is cheap, and compliant, and so is that method of splitting. OR just have that box do all the DMX and send only the voltage to power the leds to the fixture.....I could see a fixture now that is only slightly larger than an RJ45 jack.

Personally I like the XLR-5 because with the exception of some stereo mics, I have not encountered much else that uses it. The XLR-3 invites one to use improper cables, and the same may be true for the XLR-4 (any you would encounter would either be for r dc power or some proprietary interface, neither of which are likely to be the correct type of cable and in the dc power case may only have pins 1 and 4 wired. anyway just some things I would consider.

on a side note, I know a lot of fixtures use the internal y- connection for the DMX thru, but I thought I read that the spec calls for all thru's to be actively regenerated? maybe this changed in a later revision of the spec....



If I remember correctly the documentation I read said that the 'Y' branch inside the fixture could be up to about a meter (3 feet), so a 20" 'Y' branchof per fixture would be acceptable.

As far as the plug you are choosing goes, I hope that the initial conversion unit where you receive the DMX signal and put the power on the line will feature normal XLR5 plugs (IN and THRU and that the unit will basically be a buffer/splitter so that the 'branch' of LEDs is isolated and if the main-bus uses the second pair (I forget what mode it was called but basically you can use the second pair so that you can use the DMX-line in full-duplex as of E1.11-2004 optionally) that won't be interfered with by the LED branch only using the main pair.
The design with the simple M-F XLR4 is really nice and compact which I think fits your bill exactly.

Also if your units are good enough and present a low enough load to the signal you'll be able to fit more than 32 on one line, as far as I understand quality transceivers these days present about a quarter of the 'units of load' that are defined for EIA-485.
 

shiben

Well-Known Member
Joined
Jun 25, 2009
Location
Chicago, IL
Keep in mind that the XLR-4 is commonly used in the video industry as a power connector for 12VDC, so you may wish to stick with the standard pinning for those which I believe is pin 1 ground and pin 4 +12V. I assume you would then be using pin one also for the DMX line Shield? or will it be unshielded, which in theory should be fine. Personally I would use an RJ 45 for power and data ala PoE, use the same pins for power as PoE and require a home run for each light, back to a splitter box that actively splits out to the lights and accepts a XLR-5 in and thru for standard DMX lines. Does this push cost up...well yes some. however cat 5 is cheap, and compliant, and so is that method of splitting. OR just have that box do all the DMX and send only the voltage to power the leds to the fixture.....I could see a fixture now that is only slightly larger than an RJ45 jack.

Personally I like the XLR-5 because with the exception of some stereo mics, I have not encountered much else that uses it. The XLR-3 invites one to use improper cables, and the same may be true for the XLR-4 (any you would encounter would either be for r dc power or some proprietary interface, neither of which are likely to be the correct type of cable and in the dc power case may only have pins 1 and 4 wired. anyway just some things I would consider.

on a side note, I know a lot of fixtures use the internal y- connection for the DMX thru, but I thought I read that the spec calls for all thru's to be actively regenerated? maybe this changed in a later revision of the spec....
XLR 4 is used widely in the theater as a cable to send both power and data to scrollers, i cues, and pretty much any other DMX accessory that is not self powered. Most theatres have a lot of this around, and if the device is compatible with an Apollo, Rosco or other brand PSU, then you can be pretty sure that people will have plenty of cable for it.
 

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