Interference making lights flicker and change colours

[Stkilda123]

Hi, this may sound stupid to some experienced people on here, but thought i would put a post up for all the others.
This is my second year doing RGB lights, and i had a fairly good display last year, but some of my props/models had some lights changing colours and flickering when not suppose too.
I put this down to me doing it my first year and that i must of not connected some wires together properly, as i made everything, including leads from scratch.
This year i realy wanted a few singing face props, so i decided to have them made in China so they would be correctley contructed.
Well today came and i conected the singing faces, and the same thing, lights changing colours and flickering.
I also make all my own waterproof outside boxes to have the smart controllers in, and i spent heaps of time making sure they had crimp terminals and everything so there would be no interference.
So after a while of pulling my hair out i decided to unplug the cat 6 cord, which was running through a waterproof gland with my pigtails, and put a new cat6 in, but keep it away from my pigtails.
And as soon as i did this, everything was doing what it should, no flickering, no pixels coming up red when they should be green.
I'm sure some of you are saying why would i do that in the first place, but i had no idea the pigtails would interfere with the signal.
So just tought i would put it out there in case anyone else is having the same issue,
Now tomorrow i start pulling all my boxes apart and re-wiring them to keep the cat6 away from everything!

 

[Adam V]

So you think the cat6 omitted interference? I have just installed everything in cat6a (kind of worried now)

 

[TANSA]

It could have been 1 of 2 things.
Bad cat cable from the start.
Or as the electron (electricity) moving through the wire and creating a magnetic field that was close to the cat cable was causing the interference.
All electrical currents cause magnetic fields to a different degrees, which in turn causes electric voltage/current in a cable that is close to it.
EG don’t have mains cable close to low voltage cable or your data/network cable.

 

[TerryK]

Most consumer Ethernet cables are UTP (unshielded twisted pair) and as such are susceptible to electrical interference when in close proximity to other cables carrying some form of AC. That can be either the normal AC (50/60 Hz) or something else (pixel data 400/800KHz perhaps). The longer the cable the more likely a problem from interference which can also be aggravated by the typical signal degradation over long distances (wire resistance/capacitance).
Industry uses quite a few shielded TP Ethernet cables but the cost per cable is greater and it requires a shielded RJ-45 jack to correctly carry through the shield ground. And then the associated concern about ground loops.

It could have been a bad cable but I'm more inclined to think the cables were too close together. An easy check is to reconnect the old cable but lay it out on the ground, not through any enclosure openings. Power up the display and gently wiggle the cable near the connector to see if the display operation goes weird. The wiggle should bring out a loose or broken connection in the RJ-45 plug.
You mentioned a cable gland but parallel runs inside the enclosure are also not advisable which I must admit is not always easy and sometimes just not possible. Ideal solution is to cross cables at 90 degrees if one is able to.

 

[BAZMick]

At work we manufacture office screen partitions. The Aus standard for data cable is to be no closer than 150mm (6") when unshielded near mains power. If this is not possible then we must provide segregation by means of a metal or MDF division panel.
So yeah, keep the data cable as far away from any EMF producing wires or devices as possible.

 

[Adam V]

At work we manufacture office screen partitions. The Aus standard for data cable is to be no closer than 150mm (6") when unshielded near mains power. If this is not possible then we must provide segregation by means of a metal or MDF division panel.
So yeah, keep the data cable as far away from any EMF producing wires or devices as possible.

ah so away from 240v makes sence so 12v is ok tho?

 

[BAZMick]

Should be, I ran data and 12v power injection last year side by side cable tied together without issue.

 

[TerryK]

To my knowledge DC does not induce interference as does AC signals. As I recall, the theory says a current is induced by either changing the magnetic field surrounding a conductor or with a stable field changing the physical position of the conductor inside the magnetic field (or both at the same time). Transformers and motors work on this principle.

 

[BAZMick]

To my knowledge DC does not induce interference as does AC signals. As I recall, the theory says a current is induced by either changing the magnetic field surrounding a conductor or with a stable field changing the physical position of the conductor inside the magnetic field (or both at the same time). Transformers and motors work on this principle.

Are you related to Julius Sumner Miller ?? Nikola Tesla? Michael Faraday ?? By any chance?

 

[David_AVD]

The DC cable on the output of a switchmode supply will have all sorts of EMI on it. How bad it is will depend on the supply. DC power cables interfering with pixel data is not unheard of.

 

[Derf]

I believe you have purchased falcon smart receivers. Have you enabled the termination resistor on the last receiver of the chain as indicated in the manual not doing this can cause issues that you have described.

1. Termination Setting Switches

The last Differential Smart Receiver on a chain needs to have the termination set. Simply put, any receiver which does not have both of the Data Input/Output Jacks used, will need to be terminated. The board uses this to understand that the signal is not going any further. Without proper termination, the pixels may give unwanted results such as flickering. This is used on any board regardless of which mode the board is set in.

All four of the terminator DIP switches should be set to the same position. Up is “ON” or in the terminated position. Down is “OFF” or not terminated.