improving the Aether2 connections... ideas??

[Steve Gase]

It doesn't seem likely that this will work, but I thought I'd ask the electrical engineers for their opinion.




I want to have a single cable that connects Aether2 flood, to Aether2 flood... in a chain of 4-5 floods that receive power from a single 12v transformer.


The Aether2 uses 35W.  My transformer supplies 200W and I've been connecting 4 floods to each transformer so far. 
I can imagine a scenario where I might use 300W transformers and string together maybe 7-8 floods.


Up to now I've been running heavy landscaping wire to all floods with the landscape lighting vampire connectors to attach the floods.  Up to now, I've also been using a separate cat5 run to daisy-chain the Aethers with a pair of rj45 pigtails.


Problems:
The rj45 connectors suffer corrosion, even when turned downward.
The vampire connectors can easily lose their bite.




I'd like to go to a power-over-cat5 solution carries DMX and 12V AC -- similar to my other 12V DC solutions.  I'd use water-proof connector of a different style to avoid mismatching AC and DC solutions.   I would build specialized extensions to connect the floods together.


I need one twisted pair to carry DMX, but I'd like someone to tell me how much capacity is available in the remaining 6 wires to carry 12V AC.  Could it carry 200W (17A)?  The wire I am using is 24 Guage AWG.




I think what I need is another type of cable... ideally carrying a single 24 gauge twisted pair, and ALSO carrying a 12-gauge pair in the same casing... and then, I'd need an appropriate connector that can move 300W across 2 of the pins.


A less elegant solution is to use a couple sets of connectors and cable runs...   each idea I consider makes me think "yuck!"


Anyone have a good solution?

[arw01]

If I am not mistaken dmx is more of a serial rs485 from what I have read.  I don't think it requires a twisted pair like pixelnet does.  You might be able to use a 6 or 8 conductor cable with 2 for the rs485 dmx, and the rest to haul the power.

To experiment take a dmx line from way across your yard with some of the alarm wire you likely have and see what happens.

Alan

[Steve Gase]

If I am not mistaken dmx is more of a serial rs485 from what I have read.  I don't think it requires a twisted pair like pixelnet does.  You might be able to use a 6 or 8 conductor cable with 2 for the rs485 dmx, and the rest to haul the power.

To experiment take a dmx line from way across your yard with some of the alarm wire you likely have and see what happens.

Alan

pixelnet is a derivative of DMX, it has faster timings and a larger packet size... but it uses the same basic componentry.  The DLA USB dongle, using the rs485 part uses the same platform -- just different firmware -- to do DMX or pixelnet.


While twisted pair is not a REQUIREMENT for either protocol, it will extend the reach because the +DMX/-DMX lines -- or the +Pixelnet/-Pixenet lines can use the twisted pair for improved signal integrity.   


...at least that is how I understand it.


My fear about using the 6 remaining wires for power is that people already discuss the limitations of running a 4A string over cat5 for pixelnet.  Doing 200W over the same wiring configuration seems very unlikely.  I just need someone to...


A) tell me that cat5 for the 200W is a fool's dream
B) suggest another cabling solution that will let me run signal and 200W of power

[tbone321]

I can bet that if you intend to run high current AC in the same cable as your DMX signal, you will probably need twisted pair for any real length at all.  I did see some twisted pair 16 guage speaker wire from Crutchfield that would probably work for you but at around a dollar a foot, it seems a bit expensive to me.

[meman]

I think it all boils down to distance and resistance of the specific wire you are using. Cat5 doesn't seem like a good choice for applications in this power range. The voltage drop calculator on this link may help to visualize the problem You are not allowed to view links. Register or Login

I run two circuits with 4 Aether IIs spaced 15' apart on each, using regular SPT1 zipline (18ga) for power. Even with the extra load capacity of the stranded wire, I use this configuration to keep resistance/distance down from the power source and everything runs fine.

cat5 _   _________   __________________   _________   _____________    _________   __________________   _________       
        |  |               |  |                               |  |               |  |                       |  |               |  |                               |  |               |   
     Aether------- Aether------12vAC------Aether-------Aether                  Aether------- Aether------12vAC------Aether-------Aether

Good Luck,
Mike E.

[Steve Gase]

hmmm.... 

If I situated the transformer in the middle of 4 Aethers, then I'd only have half of the power moving over cat5 in the northbound, and the southbound directions.  Only DMX would be continuous along my run of 16 aethers.

In this diagram I am trying to represent a single cat5 cable, 2 wires for DMX, 3 wires for 12v AC Hot, and 3 wires for Neutral.  Each group of 4 aethers has a transformer in the middle.  The power does not get passed on from one group of 4 to the next group of 4.  ...but the DMX is passed on.

2=dmx==+====+========+====+==========+====+========+====+==========+====+========+====+==========
3_12v__+____+__PWR1__+____+          +____+__PWR2__+____+          +____+__PWR3__+____+
3_GND__+____+__PWR1__+____+          +____+__PWR2__+____+          +____+__PWR3__+____+
       |    |        |    |          |    |        |    |          |    |        |    |
      Ae1  Ae2      Ae3  Ae4        Ae5  Ae6      Ae7  Ae8        Ae9  AeA      AeB  AeC


I need to think about this... does the complexity make things any easier?  I'd need an injector for each transformer (situated between every 4 units), and also a connector that does not propagate power lines (situated between every 4 units)...

Maybe its not all that complicated.  hmmm...

My diagram is just like yours, Mike... except I'm still thinking I can put the power on the cat5.

BUT... as you point out, the drop-off is significant.    Moving up a couple sizes on the cable and maybe I'd have something.

[arw01]

I think Tbone's post on speaker wire could be a good lead.  Check car stereo wiring, it's typically available in very large gauge and twisted pair.

Another thought is to just ziptie the cat 5 to the power cable, and although it is not in one sheath for the run, it's still available on just one connector.

When I was reading the specifications for RS-422/Rs-485 and it's ilk last night on Maxim's website, it mentioned thousands of feet being available for distance in noisy manufacturing and other commercial plant locations with shielded twisted pair.

Alan