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Thread: HOWTO: safe LED lighting for haunted houses

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  1. Lightbulb HOWTO: safe LED lighting for haunted houses 
    Join Date
    Apr 2009
    Santa Clarita, CA
    The trend with LEDs is becoming more popular in our daily lives (stop lights, TV, computers, instrument panels, etc...), in this post I will try to convince you that LED lighting is way to go for 99% of your haunted house lighting needs. This post isn't for promo purposes but simply to inform about safe lighting practices and to illustrate the benefits of placing more focus on lighting in your haunt. Please feel free to post any technical questions you may have and I'll try to the best of my knowledge to answer them.

    Why use LEDs?
    1. Safe --- LEDs are low voltage and generates very little heat, reducing risk of fire dramatically, this reason alone should convince you to use LED lighting in haunts. You can also hide LEDs in virtually any material w/o worrying it'll catch on fire.
    2. Durable --- LEDs typically won't shatter when dropped, there are no moving parts or hollow spaces. LEDs can even be made water resistant or water proof with the correct type of casing.
    3. Energy efficient --- the amount of light per watt of power used is significantly better than traditional incandescent lights. This year, LEDs will exceed the efficiency of compact florescent lights (the curly light bulbs).
    4. Environmental friendly --- there are no toxic substances in the LED, there is mercury in fluorescent lighting. In case you do manage to break an LED, you won't have to worry about dealing with hazardous materials.
    5. Easier to install --- Although I don't know all the local fire codes, I don't believe low voltage lighting wires require running it through conduit, this will save a lot of time when running your wires around.
    6. Directional light --- LEDs inherently emit direction light, making them great spotlights.

    Why are people still using the traditional bulbs?
    1. Perhaps their haunt was built way before LEDs got popular, it was probably a lot of work to install the electrical system and they haven't felt the need to switch over
    2. LEDs may seem like unfamiliar territory because they come in so many types and very few (until recently) are compatible with traditional light fixtures
    3. For making your own LED lighting system, it does take some basic technical understanding of electricity.

    LED Basics
    LED stands for Light Emitting Diode, this is a type of semiconductor that will light up when a voltage is applied to it. Because LEDs are diodes, polarity matters --- that is, in order for the LED to light up, the positive voltage must be applied to the anode and the negative voltage must be applied to the cathode. LEDs typically light up with only 1.3V - 4.0V applied to it, this voltage is specified in the LED's documentation and varies between colors and models. One important thing to understand is, simply hooking up a small battery to a bare LED is NOT good practice. This is because your battery is not limiting the current that will be applied to the LED. The LED may still light up, but you may be significantly reducing its lifespan or burning it out. If you ever buy a really cheap key chain LED light (for about $1) and open it up, often you'll see a bare LED straddling a 3V button battery --- this is as cheap as it gets, the LED will light up but not reliably (you'll probably notice in the long run your LED may not be as bright as it used to be). The proper way to light an LED is to have a RESISTOR in series with the circuit to limit the current flowing through the LED (I'll explain how this works below). For more details, go to Wikipedia: http://en.wikipedia.org/wiki/Led

    Differences between LEDs and traditional lights
    1. Polarity matters: if you reverse the polarity on an LED, it just won't light up
    2. LEDs are not dimmable in the same way that traditional lights are -- will go over this in more detail below
    3. LEDs run on low voltage, even if you have LED bulb that screws into traditional 110V or 220V sockets, there is circuitry inside that steps down the voltage

    How to light up a SINGLE LED from a 9V battery properly
    Assuming you have a single RED LED with a turn on voltage of 1.7V and handles up to 20mA of current (usually these specs are on the website from which you purchased the LED or on some type of packaging that came with it), here's how you get it to light up reliably (we require some basic electronic principles).

    With a 9V battery, 1.7V will be dropped across the LED, that means 7.3V still remain --- this voltage will be dropped across a current limiting resistor, which is in series with the circuit. Since we want at most 20mA travelling through the LED, that also means at most 20mA will travel through the resistor. By basic Ohm's Law: Voltage = Current * Resistance we get: 7.3V = 0.020A * R, if we solve for R, we get 7.3/0.02 = 365 Ohms. This means you want to use at LEAST this resistance in your circuit because this limits the current to at MOST 20mA. You probably won't find an exact valued resistor for what you calculated, just use the closest standard value that is HIGHER than what you calculated. More resistance = less current. Below is a simple diagram and a really useful tool for calculating the resistor value needed for your LEDs.


    You'll realize most of the 9V we started out with was dropped through the resistor (7.3V) and only a small portion of it (1.7V) was through the actual LED ---- this is pretty inefficient as most of the energy was simply burned off as heat through the resistor and not as light. A more efficient way to do this is hooking up several LEDs in series on the same circuit:

    In the picture above, 3 LEDs are hooked up in series, meaning 5.1V (3 x 1.7V) is dropped across it and only 3.9V needs to be dropped across the resistor. By the same calculation method above, you'll get 3.9V = 0.020A * R, and solving for R we get 195 Ohms. Of course there is a limit to how many LEDs you can put in series, the total combined voltage drop MUST be less than your voltage source. If you're running off of a 9V battery like in the diagram, you'll also want to account for the battery's voltage lowering as it starts to run out of juice. Say the battery can potentially drain down to 8V, then at MOST you can hook up 4 LEDs in series.

    Dimming LED lights:
    Traditional light bulbs dim out when a lower voltage is applied to it. This will work for LEDs to SOME extent but you won't a very smooth transition between ON, DIMMED, and OFF. The brightness of an incandescent light is proportional to the voltage applied to it. The brightness of an LED is proportional to the CURRENT running through it, however this is much more difficult to control. There are two ways of dimming an LED, one way is simpler and less efficient, the other is more complex but very energy efficient.

    • Simple but inefficient: if you add a potentiometer (a variable resistor) to the circuit above, you can throttle the current through to the LED.
    • Efficient but more complex: LEDs work more efficiently when they are either fully ON or fully OFF. If you're switching the LED ON and OFF very fast (more than 100 times per second), you won't be able to see the flickering. During this ON and OFF cycle, if the ON time is more than the OFF time, your LED will appear brighter. If the OFF duration is more than the ON duration, the LED will appear dimmer. By varying the relative pulse width between ON and OFF, you'll be changing the perceived brightness of the LED, kind of like taking an average of the light output. This technique is called "Pulse Width Modulation"

    Most low voltage LED dimmers work in this fashion. For example here:

    Using a LED lighting system in your haunt
    Most low voltage lighting systems on the market are using 12V, it's pretty standard because you can find 12V in a bunch of places:
    • Standard wall warts (you can rip it off some existing appliance or buy a universal one from Radio Shack)
    • Car batteries
    • Regulated power supplies specially designed for LEDs

    Most of your haunt probably is using 110V AC power --- you'll need to find a way to convert it down to 12V DC, most of the time people can just go to Radio Shack and buy a 12V power supply. Just make sure the the total current being used by the LEDs do not exceed the current rating of your power supply. For example, if you have a 2.0A power supply at 12V DC, and each LED you have uses up 20mA, that means you can took up at MOST 100 of these LEDs in parallel. Once you have your 12V source, you can use terminal blocks to distribute the power to your individual LED lights.

    One great thing about low voltage lighting is the ease of installation --- since you're not running much voltage (or current), you won't need really thick wires (unless you're running your wires several hundred feet). For the most part, 24 AWG speaker wire is a cheap and effective way to light up your LED system. You can also use ethernet or telephone cable, pretty much any wire around the house will work. For wire management purposes, it is recommended to use one power adapter for every few adjacent rooms instead if wiring up an entire haunt with just a single adapter.

    If I haven't addressed any technical part to this point, please comment below and let me know.

    The world's SMALLEST and BRIGHTEST LED spotlights! Built for haunters.

  2. Lightbulb lighting techniques with LEDs 
    Join Date
    Apr 2009
    Santa Clarita, CA
    Now, for the the lighting techniques: this part is more subjective and everyone's opinion may vary --- discussion is welcomed

    I want to start off by asking the rhetorical question: "What good is your $5000 animatronic if no one can see it?" Many people spent tens of thousands of dollars on building their set, awesome animatronics, but pay little attention to the lighting. I dare to say that lighting can make or break your scene. It brings out what you want your visitors to see and hides what you don't. It's great for misdirection, mood setting, and showing off all the hard work you went through to put your haunt together! I've been through several haunted houses on tours where we go back during the lights-on saying "I wish I had seen that in the dark, I didn't even know it was there!" On the contrary, you also don't want to walk in to a haunt where you CAN see everything, then there's no mystery --- this is why LEDs are perfect, they're not as bright as traditional lights, and can highlight JUST enough of what you need, nothing more and nothing less.

    LEDs are also great because they come in so many different colors and tend to give more of a pure color than your traditional par cans with gels over them. Because LEDs are directional by nature, you can use it as a spotlight for many of your scenes.

    • A single LED enclosed in a tube can pinch off the light spread making a solid spot, this is great for highlighting props or casting creepy shadows
    • Several LEDs with a wider dispersion angle can give a nice soft flooding effect to a scene, you can get a nice glow in a corner of a room
    • There are many high powered LEDs on the market now (1Watt or even 3Watt), just a single one of these can flood an entire scene with color.

    For completeness, I'll list a few examples of where to use certain colors (some may be quite obvious):
    Reds: dungeons, hellish areas, any scene with fire, blood, or guts
    Greens: alien scenes, labs, jungles, graveyards, creates a creepy mood
    Blues: cold mood, freezer, water scenes, graveyards, futuristic scenes
    Amber: this color makes anything look old (like in old color faded pictures), great for attics, barns, warehouse, also use with fire scenes
    White (cold): almost the same color as fluorescent tubes, use in offices scenes, or to highlight props that need to show full color
    White (warm): similar in color as a traditional light bulb, use it to make your scenes more natural looking, also use to highlight props that need to show full color

    Remember if you're highlighting with any of the colors other than white, you'll most likely wash out the colors you used to paint your scene. Often times your scene detail make look awesome when you have normal lighting on it, but if you hit it with a red light, everything in that scene will be some shade of red.

    I suggest to detail your set in actual haunt lighting --- this way you'll know what the final product actually looks like (or at least switch between your normal light and haunt light during the detailing process).

    Alright, I know this was a pretty long post and really thank anyone who took the time to read this. If I had left anything out, let me know and I'll try to offer my advice as best as possible. Thanks!

    The world's SMALLEST and BRIGHTEST LED spotlights! Built for haunters.

  3. Default Heads up! 
    Join Date
    Nov 2008
    Mesquite, TX
    Great tutorilal, I know alot of folks are making the LEDs from the tutorial I did a while back. It does not say in in my document that I email out on making them but the LEDs you make yourself can be controlled by Thrilltainments controllers.
    Very well put together tutorial. Great info for the undustry.
    Allen H

  4. Default LED Polarity Question 
    Join Date
    Nov 2007

    You mention " Polarity matters: if you reverse the polarity on an LED, it just won't light up".

    What about the venors that say " you can plug in any way and it will light up, no matter the polarity" (or something to that extent)

    Given the above between what you said and the others have said .. thats a bit of a contradiction isn't it ??

    Just curious.

  5. Default Now that is a dumb question....exact same question I have 
    Join Date
    Mar 2009
    I second the above.???????

  6. Default  
    Join Date
    Nov 2007

    Im no the only one with that question.

    But you know what they say (kinda sorta) "the only dumb/stupid question is the one not asked"


  7. Default LED Lighting 
    Join Date
    Jun 2008
    Avon, IN
    Thrilltainment has written a very good overview of using LED's There's a lot of good information there.

    I'd like to expand on a couple of things....

    Regarding the polarity questions, LED's are indeed polarized, and the polarity of the power supply does matter. BUT... the better LED fixtures address this by building in a bridge rectifier, so no matter what the power source's polaity, it's correct when it reaches the LED.

    It was said that LEDs are inherently directional. Granted, the LEDs we chose for our Gosling flexible LED light fixtures have a 20 degree beam angle. However, our primary supplier has LEDs ranging from a very tight 10 degrees to a very wide 130 degree angle. The LEDs used in our ProLight-200 fixtures cover nearly 180 degrees.


    Pulse Width Modulation (PWM) is absolutely the best way to reliably dim an LED in most situations, but there are exceptions where varying the voltage (and ultimately the current) is the only choice. Great care must be taken to make sure that you are not using switch mode, regulated or constant current power supplies when connecting LEDs to FireFly, Chameleon and miniFLICKER controllers from Lights Alive. The same rules hold true for sequenced lighting systems, such as Light-O-Rama. Lights that do not contain linear power supplies designed specifically for the flashing, flickering and dimming from these controllers will not perform satisfactorily and they may fail altogether.


    It is true that most any power supply can work for small LEDs, but keep in mind that just because a power supply says 12vdc, doesn’t mean that it will output 12 volts. That rating is generally when the power supply is fully loaded. We have tested some 12-volt power supplies that exceed 20 volts until they have a full load applied. This is not true with regulated power supplies, but it is an absolute with non-regulated supplies. The higher voltage causes a higher forward current through the LED, which can dramatically shorten its life. For this reason, we would recommend that you not buy the largest power supply (wall wart) you can find. It is much better to buy one that is rated just slightly higher than your load. Again, this is true only for linear power supplies and does not apply to regulated supplies.

    We’ve heard a lot of talk about LEDs not lasting the 50,000 to 100,000 hours that many manufacturers specify. The fact is that very few LEDs fail unless too much current is applied. However, many cheap (department or home store type) LED light strings fail because connections within the strings corrode due to moisture and oxidation, just like your old Christmas light strings. When it comes to LED light fixtures or replacement PAR style bulbs, it is generally the internal power supplies that fail, not the LEDs.

    Since there is no filament to burn out, that 50,000 to 100,000 hour lifespan does not mean that the LED will cease to emit light. Depending on the manufacturer, it means that the LED will be emitting somewhere between 50% and 70% or its original intensity. If the fixture ceases to function, it’s almost certainly the internal power supply or the connections rather than an LED. That said, a tiny (very tiny) percentage could fail.

    Regarding polarity, it is very true that LEDs will light only with the proper polarity. However, most quality fixtures use internal diode bridges to alleviate this issue. When the diode bridge is used, the fixtures will light in either polarity and even with low voltage AC supplies, such as landscape lighting transformers.

    When choosing LED replacement bulbs from overseas, keep in mind that they were likely designed for 220 volts AC, 50 Hertz. Of course the standard here in the United States is 120 volt, 60 Hertz. Due to the limited space and a desire to keep the bulbs cost effective, manufacturers often use capacitors to drop the voltage inside these bulbs. Those manufacturing “cheap” bulbs often cut the 220 volt circuit in the middle and parallel the resulting circuits to make a 110 volt bulb, but that can be quite problematic. First, it is very poor design practice to parallel groups of LEDs unless they each have their own current limiting resistors. This method can cause early and catastrophic failure. Then there is a significant difference in capacitive reactance from the 50Hz used overseas versus our 60Hz. And, then we supply 120 volts to a system designed for 110 volts. The combination of these three issues causes unreliable operation and premature failure in many PAR style replacement bulbs due to overdriving the LEDs.


    BRIGHTNESS – When customers call us about LEDs, the first two questions are “how many watts?” and “how bright?”. This may be the toughest of all questions to answer. We all understand watts when talking about incandescent bulbs, but the amount of current utilized by an LED doesn’t necessarily translate into brightness. The typical unit of measure for brightness for small LEDs is millicandela or MCD. For instance, a small 5mm (T1-3/4) LED may be rated 25 MCD when used for indicators in electronic circuitry or you may find one rated at 15,000 MCD, both of which are typical 20 milliamp (mA) LEDs. When considering brightness, forget the current forward current rating and concentrate on MCD. The higher the number, the brighter the LED.

    When comparing high power LEDs, such as those used in our ProLight-200 LED fixture for FireFly lightning simulators, the unit of measure is lumens. Incandescent bulbs typically emit about 11 lumens per watt, so a 100-watt bulb would average around 1,100 lumens. We use two (2) 18 watt LEDs with a total output of up to 2,500 lumens or more than a typical 200 watt incandescent bulb.

    The efficiency of the power supplies used to supply low voltage to LEDs varies widely and the efficiency of the LEDs themselves can be quite different at different current levels and even from batch to batch. In other words, lumens are the only true way to compare LEDs among themselves or to other types of lights.

    With both owners of Lights Alive having spent much of their lives as professional photographers, we have many suggestions on proper lighting, which we will address in a future posting.
    Steve Peterka
    Lights Alive

  8. Default  
    Join Date
    May 2009
    Dark Light & Lights Alive -

    Thanks for putting well planned and illuminating info out there both in your booths and on here. You guys are nearly peerless in your willingness to get into the details and applicable functioning of your products - From one geek to another grazi. Allen, this is by no means calling you a Geek as well, though if the slide rule fits...

  9. Default Thank you Steve And Darklight 
    Join Date
    Nov 2007
    Steve(Lights Alive) and Darklight~

    Thank you both for your very informnative posts .. I have been trying to talk the boss of the place I work at (cave) to switch to LED lighting.. (Floods and spots) .

    Unfortunately .. he( and I do have to agree) they are still quite "cost prohibitave" considering the ammount of lights we would have to replace. (close to 100 Incadecent lights of various colors) BUT considering the saving we would have LONG RUN .. it kind of works out ... its just the INITAL cost to switch that is worrying. Which im sure is on others minds as well considering the encomy and such as it is no matter what the setting/situation happens to be.

    And I'm NOT IN ANY WAY knocking down the advantages of having LED lighting, but, I do have to say .. with the setting that I work in (cave again) in some areas they seem to give off somewhat of a "harsh" light .. yes I know there are "difffusers" you can get ..but those can only do so much especially in certain settings..

    Now for Haunters I can DEFINATELY see a marked advantage or Using LEDS vs. Incandecent bulbs.

    First and foremost MUCH LESS of a "fire hazzard" As has been mentioned LEDS put off little to any heat. Thereby, alleviating the fact if you have an LED "buried" on or in say a pile of leaves or mulch or something that MAY ignite... theres much les of chance of that happening vs. usinf a Incadecent or "squiggly" florescent( yeas the latter DOES produce quite a bit of heat especially in an enclosed space such as a "light globe" or some such".

    Second they are compact .. and EASILY transportable .. meaning .. MUCH LESS risk of breakage if say you are moving them around from one place to another or puttng them in storage.

    Third and lastly .. SAFETY which goes along with the above (breakage and such) .. not much more to say on that especially in a Haunt setting.( or any setting for that matter)

    Mind you these are just my thoughts on this matter . Thank you both again for (so to speak) "Shedding more light" on this subject.

    Last edited by lonewolfmage; 03-22-2011 at 10:51 AM. Reason: Edited to add a second thank you ... My apologies.

  10. Default "Dual Polarity" in some LEDs fixtures 
    Join Date
    Apr 2009
    Santa Clarita, CA
    Quote Originally Posted by lonewolfmage View Post

    You mention " Polarity matters: if you reverse the polarity on an LED, it just won't light up".

    What about the venors that say " you can plug in any way and it will light up, no matter the polarity" (or something to that extent)

    Given the above between what you said and the others have said .. thats a bit of a contradiction isn't it ??

    Just curious.
    Hi LoneWolf,

    That's an excellent question. You may have actually heard that "you can plug it any way" quote from me at the show =)
    In our Darklight line of products we add an additional diode bridge with corrects the polarity reversal. LEDs by themselves are inherently directional (as with almost any consumer electronics), but usually the product will add additional circuitry to correct the problem to make it easier for the consumer to use.

    Below are two pictures from Wikipedia that demonstrate the diode bridge (red line is positive voltage, blue line is negative voltage):

    As you can see above, no matter which way the positive line comes in, it always ends up being rectified to the correct polarity that the LED can handle. Although the addition of this circuit adds costs to our products, it makes them much easier to install for the consumer.

    Another implication of adding this diode bridge is that you can even power the lights using 12V AC power (since AC is basically switching polarities at 50-60Hz). I know of some haunts who don't use 12V DC wall warts but simply steps down their 110V AC with a transformer down to 12V AC... this will work with our lights (and any other vendor's light that has a diode bridge). If you happened to try 12V AC power on a standard diode circuit like in the original post, you may notice the diode will strobe/flicker very quickly as it will only light up approximately 50% of the time (when the polarity is correct).

    I hope this sufficiently answers your question.

    - Quan

    The world's SMALLEST and BRIGHTEST LED spotlights! Built for haunters.

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