In the past several years LED lighting has transformed itself from little red indicator lights with very little luminescence, to uses that vary from high-output white flashlight lamps to brake-indicator lights in main-stream automobiles. What this means for the home and professional haunter is that commercially available LED based lighting devices are here to stay and are quickly becoming affordable.

LED lighting offers many benefits to both the home haunter and the professional haunter.

Solid state design: No glass bulbs to break or filaments to burn out.
Low heat: LESS worry of props catching fire or melting from a hot bulb.
Low Voltage: An entire haunt's lighting can be powered by a single low-voltage transformer. Very little danger of electrocuting your guests!
Portable: With batteries, you can place lights in otherwise hard-to-light areas. And, the batteries won't need changed the entire evening!
Lifespan: The average LED lasts >5000 hours and is not degraded by turn-on cycles, temperature or vibrations.
Color: LEDS emit light at specific wave-lengths (with the exception of white). No more expensive filters!
Fully dimmable: Easy to adjust to just the right amount of light.
Strobe-able: The same lamps that offer constant illumination can instantly be turned into strobe lights.

With these benefits come a few trade-offs:

Price: LEDs are more expensive per lumen (light output) than their incandescent counterparts.
Power: Although they are low-voltage devices, they are also constant-current devices. This means that special drivers must be built or bought to properly power them.
Viewing angle: By nature of their design, LEDs have a fixed viewing angle (like a flashlight). You will not get 360^o of illumination from a single LED. This can be a plus or a minus depending on the area you want to illuminate.
Heat: High-power LEDs produce heat and this heat must be dissipated or the LED will die.

In my introduction I mentioned that "commercially available LED based lighting devices are here to stay and are quickly becoming affordable." For the do-it-yourselfer, LED lighting is already very affordable and very much doable with a few simple skills. Let's start out with the different types of LEDs you can purchase:

Standard (T1) LEDs

These are the most common LEDs on the market today. The case is made of acrylic which acts as both the die holder and the lens. They typically have two leads for power - a cathode (+)(short lead) and an annode (-)(long lead). Common commercial uses for these are keychain lights, indicator lights and center stop lights on automobiles (especialy in wings).

These LEDS are generally not extremely bright over a long distance. The brightness of these LEDs is rated in micro-candles (mcd) with typical values between 6 mcd and 10000 mcd. Most viewing angles are between 5^o and 70^o but can be found as wide as 180^o with an inverted cone lense. If looking to buy these LEDs, a good name brand supplier is a must for consistency and longevity. Good name brands to look for are Nichia and King Bright. Cost ranges from a few cents a piece when bought in bulk from e-Bay (direct from Hong Hong), to a few dollars a piece when buying low count, name-brand LEDs.

In a haunt, these LEDs work well for illuminated eyes and small spot lights. Combining a bunch together can give fairly good results as a flood light, but I believe you are better off with high-power LEDs for this use. Adding a couple of these in low-angle high-brightness configurations work great for laser-like effects in fog filled rooms. They can also be used in combination with scuffed acrylic pieces for walk way markers.

Powering these LEDs is very simple. All that is generally needed is a power source greater than the LED's power requirement and an in-line resistor.

There are tons of LED resistor calculators out there. The one I tend to use the most can be found Here.

High-Flux LEDs

Commonly refered to as Spider LEDs, their most notable use is for rear break lights and turn signals in automobiles. The typical viewing angle is 120^o and the better ones are rated in lumens (lm) rather than micro-candles. Output ranges from .7 lm to 2.5 lm. This puts them at about 3 times as bright as high-brightness T1 LEDs with a much larger viewing angle to work with.

I currently use these as spot-lights in my grave yard. The down fall is the higher power consumption required makes them almost too big to use resistors with but too small to justify building or buying a constant current power supply.

Luxeon LEDs

Certainly not the only high-power LEDS on the market, but the most affordable and easiest to work with that I have found. Luxeon LEDs come in 5 basic varieties (as of July, 2007): Luxeon I, Luxeon III, Luxeon VI, Luxeon K2, and Luxeon Rebel. The output of the Luxeon LEDs are rated in lumens (lm) just like the High Flux. They rage from 14.5 lm for blue to 114 lm for dental blue. For comparison, a typical incandescent 40 watt light bulb is rated at about 280 lm. On the opposite end of the spectrum, the Luxeon Rebel range from 8.2 lm for blue running at 350 mA to 180 lm for white running at 700 mA. This dual current rating is unusual in the LED world and it should not be interperated that all LEDs are designed to run at such huge current variances. The real amazing part of the Luxeon Rebel is its size: about the size of the positive post (the knob that sticks out) of a AAA battery (yes AAA!). Unfortunatly the thermal requirements are not easily met by the average person etching their own circuit boards (multiple copper clad through-hole thermal pipes on 2 oz double-sided circuit board).