LED Christmas Lights on a dimmer

CBR372

Active Member
Hey guys I got a question for all of ya. Im designing a show right now and the set designer wishes to use LED christmas lights in the set. I as the LD don't wish for them to dim, just on or off, but I would like control from the board, and I have no access to a Relay or Constant on dimmer. So my question is will I face any issues plugging directly into a regular dimmer (Either ETC Sensor or Strand CD80 supervisor or more current) Any input would be great, thank you.
 
The only thing you might need is a dummy load, but for general on off (depending on your console most have some type of full at 1%) christmas lights usually work pretty well.
 
As Chris15 said, if there is a transformer (and I don't know of any commercial LED string that doesn't use one) then it's not a good idea. Yes, it'll work. Until it doesn't. And that will hopefully be because you broke the transformer and not the dimmer.
 
As we've discussed about a million times, the phase-control SCR dimmer is intended for resistive loads (incandescent lamps) only. IF a device has a transformer, power supply, motor, diode, etc., it probably won't enjoy like being run though a dimmer. Can you "get away" with powering LED xmas strings? Probably. They may even dim smoothly and not erratically or with flicker. The worst that will happen is that the string(s) will never light up again. (IMO, the threat of damage to the dimmer is greatly exaggerated.) But please don't put moving lights or anything expensive that you can't afford to replace on a dimmer. There is no profile or magic setting on the console or in the dimmer's brain that can trump physics.

A ghost load may make the dimming curve smoother (and/or allow it to fade completely out), but probably will not make the device any happier. The phrase "At your own risk" seems applicable. "Do ya feel lucky, punk? Well do ya?"
 
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In the US, most LED strings (all the residential grade ones I have seen, and most of the commercial ones) simply use a diode (either half-wave or full-wave) and current-limiting resistors. Even the ones with a built-in sequencer use resistive or capacitive dropping. Transformers just cost too much.

Both full-wave and half-wave strings will work on a dimmer; the half-wave ones tend to flicker more. Many of the dimmers for the animated lighting world have 47K snubber resistors (ghost loads) and programmable curves to help even things out. You still can have problems on the low end with leakage current letting the string glow faintly; just a few mA of current is visible.
/mike
 
Always try to post this in the LED threads: Doug Fleenor Design - 8 Channel DMX Dimmer
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Doug made it specifically for CFL and LED.
 
At Cedar Point we use lots of LED Christmas lights! We run them through ETC DDR and Smartpacks to dim these lights. We have no problem with dimming, though we have had to put some snubbers or incandesent loads inline at some trouble spots.

We use commercial grade lights but I have personally used walmrt type lights with a Light-O-Rama board with a snubber and had no issues.
 
For what it is worth, we also use LED Christmas lights on dimmers with no issue. Most of ours are the cheap hardware store type. They turn on and off just fine on the dimmer, but we have had to use a string of incandescent lights as a ghost load for them to dim smoothly.
 
Matt/ Morte615 is talking about the starlight experience
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PointBuzz - Cedar Point Starlight Experience
as far as snubbers he may be talking about the GFI's they've got around the system @7:30 I will say it's quite a system they've got spread out through that area of the park.
 
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Matt/ Morte615 is talking about the starlight experience PointBuzz - Cedar Point Starlight Experience as far as snubbers he may be talking about the GFI's they've got around the system @7:30 I will say it's quite a system they've got spread out through that area of the park.

Actually what I as talking about are small male plugs that have a resistor placed between the two prongs. Not sure of what size resister but that is pretty easy to find online. Also they use C7 bulbs inline that work the same way, though he C7's are usually plced in the boxes with the dimmable GFCI's to keep them out of sight. These were added after the video was shot so you don't see them there.

I am not on a computer so won't fill out the wiki post yet (I will get to it tomorrow if no one beats me to it) but pretty much a snubber (or dummy load) is an item that is placed inline with the LEDs that draw a small load and make sure that the LEDs turn all the way off and to prevent unwanted flicker.

But Josh is correct on what show I was taking about, I worked this show part time during the summer so became very familer with it! :)
 
... that area of the park.
What!?:evil: IMHO, the attraction is totally incongruous with Frontier Trail, which in my day :angryoldman: was lit with gaslamps, IIRC. No really, gaslight. And before a smart aleck asks, NO, it wasn't because the incandescent bulb had not yet been invented.

Other random thoughts:
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I wonder which was the Las Vegas-based lighting company?;)
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6m43s: I didn't see the presenter LOTO that Hoffman enclosure before opening it up and sticking his fingers in there. (Although he might have, as there is an edit, between his opening of his Leatherman and the opening of the box.)
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7m57s: Oh great! Did he just pull out a LIVE dimmer "cartridge" ??? Without turning off the module's breakers ??? Again, LOTO may have happened off-camera.
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8m36s: "...and then we have these little colored dots here, which are called SL s..." Good thing there [-]is not[/-] has never been another product from within the Philips conglomeration with a similar name.
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11m59s: I wonder, Does "Park the channel at zero" meet the criteria for Lock-Out/Tag-Out as specified in NFPA 70E?
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All snarkiness aside, thanks for posting the video. An interesting glimpse backstage at an "architainment entertraction." I know other parks would NEVER allow such a video to be released.;)

EDIT: Cross posting to the Show Control Forum, should anyone wish to ask non-LED questions of josh88 and Morte615.

...These were added after the video was shot so you don't see them there. ...
Were these resistors/C7 lamps added after the initial installation to solve an unforeseen problem/issue? To the best of your knowledge, if you know, and you're not on trial here.;) I only ask because any type of change order/alteration/retrofit/field modification can become costly and might affect the permitting/ATP process.
 
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Another example of this being a small world we live/work in. Matt you may likely know me as one of the sliders (spiro) from halloweekends.

and derek I know and agree with it not fitting the trail, though it is actually a pretty impressive sight and provided a huge family draw for later in the night in an area that the general public has lost some interest in over the years.

and yeah I worried about those moments too and knowing how things work I'd like to think he did LOTO, especially if they had cameras on him, the company wouldn't want that on their hands.
 
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Another example of this being a small world we live/work in. Matt you may likely know me as one of the sliders (spiro) from halloweekends.

and derek I know and agree with it not fitting the trail, though it is actually a pretty impressive sight and provided a huge family draw for later in the night in an area that the general public has lost some interest in over the years.

and yeah I worried about those moments too and knowing how things work I'd like to think he did LOTO, especially if they had cameras on him, the company wouldn't want that on their hands.

LOL yep I actually recognized you from another post on here, and on PointBuzz. I was a Screamster last year in Fear Faire and worked as a fog tech this year in Screamworks.

I know that the system was designed originally to be worked on "live" while the show is going on. So opening the boxes while the show is live is ok, that's what the system was designed for. I'm not really positive but I think those dimmer channels are hot swappable and can be replaced again while live. But if not the breaker for that is right next to the cartridge and him turning it off could have easily have been missed. Though from some sories that I have heard about him Ic ould see him not botherng!
 
While designed to be able to be hot swapped you still have hot three phase rails. So still very likely to hurt or kill if touching the wrong chunk of metal. (this coming from the guy who cleaned an enr dimmers rack while it was still energized. Colortran says you could do it...)

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...I'm not really positive but I think those dimmer channels are hot swappable and can be replaced again while live. But if not the breaker for that is right next to the cartridge and him turning it off could have easily have been missed.
Just in case anyone missed it in the wiki entry Lock-Out/Tag-Out :
Even something as mundane and seemingly harmless as swapping a dimmer module (a very common troubleshooting procedure) now requires completely powering down the rack.
...Because of NFPA 70E, and its regulations on arc flash potential, we [ETC] cannot recommend hot-swapping any dimmer module while the rack is powered on. We strongly recommend that you power off the rack before swapping modules to prevent the potential for an arc-flash incident.

...I know that the system was designed originally to be worked on "live" while the show is going on. So opening the boxes while the show is live is ok, that's what the system was designed for. ...
I'd love to be shown the safety features that enable this while still maintaining compliance with NEC and 70E. When I was there our primary safety concern was the tinderbox known as the Cedars burning, with occupants trapped inside. Were that to happen while empty, there would have been a celebration!

Oh, and I never did get the true story of the urban myth about how an Altec-Lansing mixer allegedly "burned down the Frontier Amphitheatre."
 

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