DMX Signal Interferance

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Senior Team
Senior Team
Premium Member
I don't think he wants to control his fog from the console. Sounds like to me either a power drop in the circuit or electrical interference. First, I would try putting your fogger on a different circuit then the one it is currently on. Also, make sure everything is properly grounded. Lastly make sure that all the cables you have are shielded.
 

Van

CBMod
CB Mods
Premium Member
Definatly sounds like an RF interference problem. The motor in the fog machine , if I remember correctly is an induction style frame motor, these are nortorious for creating both RF and magnetic interference. Solution. put a remote on the fog machine and move it away from you. I hope you have filters on the PC you're using as well. Haveing an active fog machine that close to a PC spells trouble, Glycerin and electronics , bad combo.
 

Van

CBMod
CB Mods
Premium Member
How do I shield the cables? I tried using the remote, but it didn't work. The next time I go in I'll try extending the remote farther. Would it be interfering with the dmx to usb unit or the xlr cables or both?
IS the usb to DMX a box ? or small dongle thingy ? Actually if either is close to the fog machine they are most likely picking up magnetic interference. As a precaution I would do a couple of things.
1. move fog machine as far away as possible.
2. Make very sure you are plugged into a completely different power source, hopefully one that is completely insulated from line flucuations. it's possible that your fog machine is creating line flucuations or harmonics that are being introduced to the pc through the power. A line conditioner should take care of that, something like a high quality UPS not just a good surge protector.
 

TomyN

Member
Hi,

is your DMX line terminated correctly (on both ends)? Is the DMX wired correctly, using the right cables? What about the shield of the DMX cable?
Does the USB -> DMX converter have a seperate power suply or is it fully USB powered? Is it in a metall housing? Does wrapping the interface with aluminum foil change anything?

Tomy
 

SHARYNF

Well-Known Member
the fog machines could cause interference in several ways

One is the heater, usually takes quite a bit of current so it is possible that when you use the fog, it is pulling down the voltage and causing a problem with your pc-usb voltage connection to the light jockey

Van is correct in that another possibility is that the fog machine is creating magnetic interference, this could be in a wide variety of situations, is light jockey running on a notebook on the table with the fog machine on the floor, or is the fog machine on the table, next to the notebook, OR is the pc a tower and again is the fog machine next to it.

Magnetic interference could be causing the disk to create an error, or could be simply interfering with the data transmission from the pc to the Light Jockey unit.

I'd first as recommended move the fog machine away from the pc/light jockey and see what ahppens

on the power side of things I would make sure that the fog machine in on a completely different circut

If they need to be close and it is the magnetic interference then some sort of metal shield between the fog and the pc might help

Sharyn
 

Foxinabox10

Active Member
That's a recipe for disaster - any tech who knows what he's doing shouldn't have set you up like that.

I disagree completely in the high school (I assume that's what this is) setting. Often times a tech that is very knowledgable won't know to not do this until a problem (such as this) occurs. Many do not have a ton of formal training and learn some of the smaller problems and how to avoid them as they go.
 
So American High Schools are relying on the students (assumption) to install the power and control + design for their lights systems, now?

Gee perhaps I'm not that bad off after all!!!!
 

Foxinabox10

Active Member
Not at all. He said that the fog machine was in the booth and was on the same circuit as the computer. What I assume by that is that the closest plug was a surge protector that also served the computer and so he plugged the fog machine in there.
 

avkid

Not a New User
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I have a fan in front of it so the fog fill the room quickly.
You may have just answered the question. Induction motors(fan)on the same circuit as as computer and interface is a very bad idea.
 

cutlunch

Active Member
I went in and did some work on my set-up. Once I plugged the fogger into a different circuit the problem was fixed. I rewired everything so the fan is on a dimmer. Thanks for the help everyone!

It is good you have fixed the interface problem but you may cause yourself another problem. Unless your dimmer states specificaly that it can handle inductive loads I wouldn't leave the fan on it. Try and find another power point that is not on the same circuit as your laptop. The dimmer may be fine but if the fan plays up I would definetely take it off the dimmer.
 

avkid

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avkid

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Fight Leukemia
He said it was for additional fill in the back of the audience.
 

Foxinabox10

Active Member
Something in the chemical properties of fog allows the haze to show up better. He was putting little bits of fog into the house to make the haze more evident.
 

Van

CBMod
CB Mods
Premium Member
It is good you have fixed the interface problem but you may cause yourself another problem. Unless your dimmer states specificaly that it can handle inductive loads I wouldn't leave the fan on it. Try and find another power point that is not on the same circuit as your laptop. The dimmer may be fine but if the fan plays up I would definetely take it off the dimmer.

Usually, USUALLY, It's not the motor on the fan you would have to wory about but the dimmer itself. If the fan is set on high, and the circuit is set to operate as a relay/ non-dim things should be ok. It's when you start trying to dim inductive loads or start restricing the operation side of the load that you start running into issues. If you are using IPS dimmers things will be ok, as they are completely compatible with inductive loads.

AVKID. You mentioned a consumer remote outlet ??? You don't mean one of those zipcord things where you plug in the wall, plug in electrical device, and then have little rotary switch in your hand to turn it on and off with, do you ?
 

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