# Dummy load with no light



## Tex (Mar 9, 2012)

I'm using some strings of c7 retrofit dimmable led Christmas lights with an Elation shoebox dimmer pack. The lights have a faint glow even with the dimmers at zero. If I replace two of the led bulbs with incandescent c7's, or put a dummy load on the dimmer, the string will fade all the way out. This is a contest, so I'm limited on number of lights and I'd rather not use glass c7's on stage. Is there a dummy load I can put on a dimmer that doesn't emit light? I tried using a plug and resistors to build what the Christmas light guys call a "snubber", but I think there's more wattage there than the snubber can disperse.

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## MPowers (Mar 9, 2012)

If light is a problem, just 2-fer the light string with desk lamp hidden back stage with a 25w or similar lamp. No light? use a small heat generating appliance like a coffee maker without the crock on the hot plate.


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## derekleffew (Mar 9, 2012)

Even the ceramic heater cone that we used to burn sal ammoniac in to create haze emits some light (from the glowing red coils), but was once popular as the ghost load for dimmer, resistance.



Note: I would NOT recommend this today. Severe FIRE HAZARD if not handled properly. And sal ammoniac is nasty.

I'd two-fer in a double pigtail cue light with cages and 60W bulbs, and wrap the sides in black wrap, leaving the top open to allow heat and light to escape. Be sure to mount it away from all combustibles. Or use a "trouble light"/"drop light"; or a clip light.


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## JD (Mar 9, 2012)

200 ohm 100 watt wire-wound resistor comes to mind. Just remember, it's going to kick off about 72 watts of heat.


derekleffew said:


> Even the ceramic heater cone that we used to burn sal ammoniac in to create haze emits some light (from the glowing red coils), but was once popular as the ghost load for dimmer, resistance.



Agreed. I also have a feeling they were well above the 600 watt per channel limit on the pack.


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## NeroCaesar (Sep 4, 2012)

I have a similar issue. My string of leds are ghosting when the channel is all the way down on the dimmer (nsi D4, of course).

What I would like to do is find out if I can put a large enough resistor in a male Edison plug and plug it in on the duplex with the leds to stop the ghosting. Any idea? Besides get new dimmers  How many ohms/ watts resistor should I use in America?


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## JD (Sep 4, 2012)

NeroCaesar said:


> I have a similar issue. My string of leds are ghosting when the channel is all the way down on the dimmer (nsi D4, of course).
> 
> What I would like to do is find out if I can put a large enough resistor in a male Edison plug and plug it in on the duplex with the leds to stop the ghosting. Any idea? Besides get new dimmers  How many ohms/ watts resistor should I use in America?



Pretty much any solid state dimmer will give you the same problem. They don't like loads of less than 50 watts. Resistor value is spec'ed out in my post earlier. Problem is, you are not going to be able to put it "in" a plug. Wherever it is, it is going to be throwing some heat! 

LED strings do need to be ghost loaded. Not only are they low in wattage, they (electrically) are an open circuit until sufficient voltage is present to cause forward conduction. (Another thing dimmers hate.) With the load in place, they will go off. You will also notice a dead region at the bottom of the curve. This is normal.


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## TimMiller (Sep 4, 2012)

Changing out the dimmer will not fix this problem. But installing a 25w bulb will, you can use a black light bulb or some other weird "party bulb" and it will cut down the lumens of output.


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## FMEng (Sep 5, 2012)

Here is what you need.

WH25-680RJI - WELWYN - RESISTOR, WIRE WOUND, 680OHM, | Newark Resistors

Newark is a reliable vendor, and they ship fast. Since you stated that a pair of C7s fixed it, this is sized to dissipate about 21 Watts, which is just a bit more. Make sure it runs in free air so that it can properly dissipate heat. I would solder some #18 stranded leads to it and use heat shrink tubing to ensure that there is no way for anything to make contact with the smallest bit of bare lead.


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## JD (Sep 5, 2012)

50 watts is the safe number, but I will admit to sticking a 7 watt nightlight into an Elation shoebox dimmer once (only thing handy) and it actually worked!


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## DavidNorth (Sep 5, 2012)

FMEng said:


> Here is what you need.
> 
> WH25-680RJI - WELWYN - RESISTOR, WIRE WOUND, 680OHM, | Newark Resistors
> 
> Newark is a reliable vendor, and they ship fast. Since you stated that a pair of C7s fixed it, this is sized to dissipate about 21 Watts, which is just a bit more. Make sure it runs in free air so that it can properly dissipate heat. I would solder some #18 stranded leads to it and use heat shrink tubing to ensure that there is no way for anything to make contact with the smallest bit of bare lead.



Also make sure to mount it to a suitable heatsink and use heatsink compund, otherwise, it will not survive. Here's a link to the datasheet. http://www.farnell.com/datasheets/423255.pdf

I prefer to use 50W or 100W resistors and then only pull 20W or 50W through them respectively. Then I can mount them to a slightly smaller heatsink, in free air, and know they will not have a problem.

David


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## n1ist (Sep 6, 2012)

Most of the snubbers used with Christmas lights are 47k and only dissipate .3W on 110v. I'd try those before building ones that dump 20W per channel as those will need heat sinks, protective cases, and possibly fans if you put multiple in one box.
/mike


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## JD (Sep 6, 2012)

Problem with LED strands is it is not a snubber issue alone. There is no forward conduction until a certain voltage is reached. With "no load" on the dimmer, the firing circuit leaks voltage and this voltage builds in each half cycle to the point where there is conduction. Unfortunately, on an LED, conduction = light.


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## WooferHound (Sep 6, 2012)

I wonder if those Glade Plug-In Air Fresheners would work ?


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## techieman33 (Sep 6, 2012)

WooferHound said:


> I wonder if those Glade Plug-In Air Fresheners would work ?



Not enough power draw, not to mention them being fire hazzards.


> The basic Glade Plug-in uses 2.1 watts of energy. The fancier ones with nightlights and light shows use over 3.5w.
> 
> Adam Richardson - Blog - The Surprising Energy Consumption of Glade Plug-Ins


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## JD (Sep 6, 2012)

Light bulb in coffee can in series with a thermal fuse. Do they still sell coffee in a can ?


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## ship (Sep 9, 2012)

My norm is something backstage either in a shielded and vented box for light - this even is Soco feed thru, or just something backstage like an Inkie or clip light in the circuit. 75w is my standard lamp wattage for something to do a dummy load when in question of not working sufficiently on a dimmer.

Thermal fuse coffee cans? These are things for the history books in "do tell about them." Had a bunch of modified Pinspots that mounted PAR 38 lamps in my first theater. Could never figure out who was hot gluing the lamps to the cans. Than I later figured out later that the actual plastic lamp socket installed into the pinspots were the thing melting down and traveling down the bulb in welding it to the can. Re-wired the cans after that but was fascinating.

Also remember some lighted blow up baloons for some tennis turniments where they were using 1Kw multi-vapor lamps - very badly mounted in socket to the screen of the fan. This wasn't the problem in them failing other than snapped welds where the hot lamp would break a weld and pivot against the plexiglass 8" tube inside the baloon. Problem we found after correcting for this wee, engineering of mounting a lamp socket to a fan reflector screen problem in welds snapping, was with that the base reflector inside the arc lamp. (This a part used to reflect heat inside the lamp away from the lamp socket,) wasn't really designed by lamp type to bounce around on the way to a show. Lamps in use are for architectural install and not really a shock mounted type of lamp.

This shield reflector of heat inside the lamp at times when screwed in - often just happened by chance to bend the reflector towards specifically where the thermal switch was located inside the plexi-glass shell of the blow up balloon light fixture. A question of Math and chance, but yep, the filament shields with travel at times allowed the filament shield ment to reflect heat/light away from the under hung base, away from it, just happened to when wiggled reflect that heat directly at the thermal fuse.


Fairly easy fix - re-mount the lamp socket so it doesn't rely on the safety screen for the fan cooling it and blowing up the baloon by way of a welded assembly that incorporates all. (Also better rigging of the baloon.) Than given all the 1K multi-vapor lamps have this problem - just re-locate this thermal switch and get a better brand of lamp.

Way off subject but curious concept in studying and solving a problem. Perhaps a bit too off topic - sorry.


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## venuetech (Sep 9, 2012)

Elation LED Dummy
Elation Professional - Professional Lighting Products


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## JD (Sep 9, 2012)

venuetech said:


> Elation LED Dummy
> Elation Professional - Professional Lighting ProductsView attachment 7659



I am not sure this would work with LED light strands. I think it is designed for dimmable LED lamps and fixtures that have a power supply that presents itself the same way as a CFL does. (Diode/capacitor front end.) LED strands are unique in that they generally are a long line of LEDs in series, with a blocking diode and limiter resistor. Often their draw is 1/2 wave. 

Depending on the price, you may want to try it out, but I would set my hopes pretty low.


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## gafftaper (Sep 9, 2012)

JD said:


> Depending on the price, you may want to try it out, but I would set my hopes pretty low.



They are $20 on B&H. Twofer and a 25 watt bulb is a lot cheaper and way less hassle than any of the other ideas.


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## wolfman005 (Mar 26, 2013)

*What's inside of this?*

I know you can't run LEDs off of a dimmer. I ran across this device on ADJ. I can't really tell the purpose of it. Is it supposed to provide a load to allow the dimming of LEDs? I have run DJ effect lighting off of cheaper dimmer packs and enough current leaks through to make the lights flash every few minutes. Could this remedy this as well/instead?


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## gafftaper (Mar 26, 2013)

*Re: What's inside of this?*

So two topics here. 

First of all electronic devices don't like the way dimmers disassemble and reassemble the electrical wave for dimming. The result of running any electronic device through a dimmer is shortening of the device life (possibly immediate failure) or you might get lucky and it doesn't hurt the device at all. There is no way around that. 

The second problem is ghosting. Devices that use small amounts of energy can cause low electric leaks when they are "off". I think that's what this device does. A cheaper option is to just to plug a small incandescent lamp on the same circuit.

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## gafftapegreenia (Mar 26, 2013)

*Re: What's inside of this?*

Essentially its just a modern ghost load that allows you to turn LED affects on and off with the dimmers you already have. I doubt it has much more than some large resistors inside of it.


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## Robert (Mar 27, 2013)

*Re: What's inside of this?*

When I had trouble with "odd" loads on a dimmer I always wired two incandescent lamps to the load. Just in case one lamp burned out.


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## JD (Mar 27, 2013)

*Re: What's inside of this?*

The device in question is called a "snubber." (A true "ghost load" would heat up too much.) The concept is to use one of these if you are connecting up a passive LED string like a rope light. They basically contain a diac, capacitor, and a resistor balance out the leakage that is in the firing circuit in the dimmer pack. As to if they actually work in real life, I have not had the opportunity to find out. 

What they are not designed for is allowing you to operate a DMX LED fixture off of a dimmer pack. Shouldn't do that.


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## ship (Jun 8, 2016)

Recommending linking this "Dummy Load" post to the "Ghost Load" post as it's the same subject and answer's Derek's question on that post of another name for the subject.

I have some of the American DJ/Elation plug adaptors on order and a Lutron simulated loading on order as per the ghost load post. Play testing both next week on various dimmers as per small club touring needs. This much less creating a few of some concept of them in sending out to other larger tours having LED loadings active and interested. Lately everyone is doing LED lamps and having problems even in doing LeD dimmers.

In reading about both, the plug adaptor seems like more or a choke (better description above) - use to control warming current from a dimmer in making LED's slightly working while it should be off. Doesn't seem to add a resistance load to that dimmer in wanting about 60 watts of load to work properly. This or make it work properly with LED sensor dimmers which are also problematic in making the workings work - but often better. The Lutron product I proposed for a quote this week and in reading it's manuals, note it's rated for 250 watts per channel - two channel. That rating and dual channel made it into a decent price and cheap enough price I'll probably make lots of them in all forms. Thanks for the simaulated dummy load link!

As on the other post, my Soco six channel 60w incandescent dummy load that's inside a three space rack panel and light shielded is on hold a few months - fans were not powerful enough to work for the moment and onto other projects. The Lutron simiulated dummy load is quoted for a paid project and in this case will be mounted to the rear of the sign - each letter for a two channel chase with new dimmable 2 Watt G-16 LED lamps at 17 to 30 lamps per letter.

Spoke with Derek today in trying to find the link to the Lutron Simulated load - given I was searcing for dummy load instead of ghost load...

His further notes:
Somewhat reminds me of a device I saw many years ago at the long defunct HiLites shop: an “ACL eliminator”, a big honkin’ 3ohm resistor with huge heat sink and male plug that could replace one 250W 28V lamp in series in an ACL harness.


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