Re: [DML] Door LED's

["Owen @ Aerodrome" <owen@xxxxxxxxxxxx>]

Disclaimer:  I have no knowledge of the specific LED kit in question.  I don't have LED door lights on my DMC, and when I do, I'll be building them myself from my own hand-picked ultra-bright LED components.

That said, red and amber are probably the smart choices.  Here comes the reason why, in the form of more information than you probably ever wanted to know about LEDs:

LEDs work by emitting light directly; not by filtering the light.  For example, a red LED will actually emit red light.  You don't need to (and in fact you cannot) filter the LED light to make it any other color.  The brightest red LEDs actually have a transparent lens that looks perfectly clear when off, but the light is still red.  

By contrast, incandescent bulbs emit an orange-white light, which is filtered by a lens to make it red/amber/whatever.  For example, a red lens removes the non-red parts of the light, leaving the red to pass through.  This hints at part of the reason LEDs are more efficient -- they emit the desired color directly, so you don't have to filter them to make them red/amber, throwing away much of the light in the process.

LEDs in the red/orange area of the spectrum have been around for a long time, and have seen a lot of development.  Advances have gradually permitted shorter and shorter wavelengths, giving us yellow, green and, recently, blue and violet.  The cooler colors (green/blue/violet) are harder to make in high-output form.

To make a light that looks white to humans, you need to mix the three colors we can see (red, green, blue).  You actually need a little extra blue, because our eyes are less sensitive to blue.  Blue LEDs are usually less powerful, too.  Thus, a "white" LED is usually four LEDs in one package: red, green, blue, blue.

In addition, to give the LEDs and even whiter appearance, almost all "white" LEDs use organic phospors that "glow" and enhance the output.  These break down over time, dimming the output (whereas the LED elements themselves will last just about forever).

So, to summarize, if you use an LED that's the correct color to begin with, you're benefiting because red and orange LEDs are some of the most bright and efficient LEDs around, and because they're turning electricity directly into light that's the color you want anyway, AND they'll probably last longer than your car without breaking or fading.  If you use "white" LEDs, you're using hybrid LED/phosphor technology that will fade over time, cost more to begin with, and require more electrical power.  On top of that, you're going to put it behind a red (or amber) lens and throw away all the non-red (or amber) parts of the light anyway.

Aside from being more efficient, LEDs have two other major advantages:  1) they're solid state (i.e. no moving parts), which makes them last almost forever, and 2) they turn on instantly, whereas incandescent lights fade on over the course of approximately 0.1-0.2 seconds.  For this reason, I believe LED brake lights are safer.  0.2 seconds might not sounds like a lot, but at 65MPH, 0.2 seconds is about 20 feet, which I believe could make a difference in a rear-end collision situation in some cases.  The instant-on effect is quite jarring and grabs the attention like nothing else.  If you've ever been behind a vehicle with LED turn indicators or brake lights, you've probably seen what I'm describing.

If you've made it this far, here's one thing I'd recommend doing if you're going to use a production LED kit:  Make sure the LED color matches your filter color pretty closely.  

For example, if you put a red LED behind a blue filter, you WILL NOT GET BLUE LIGHT.  You'll get almost nothing -- black.  This is because the red LED emits only red light, and the blue filter removes everything but blue, leaving NOTHING.  You would never do this in practice, of course, but the same idea applies in putting a red LED behind a red filter -- if the filter doesn't match the color of the source light, the output will drop off severely.

Regards,
Owen

VIN 10470 "1 21 GW"



M. P. Olans wrote:
> 
> 
> Hi all,
>      For everyone who has converted their door lights to LED's, I have
> a question: did you go with white LED's or red and amber?  What is the
> advantage/disadvantage with red and amber LED's vs. plain white?  I
> saw them on a car at the last show I was in and the owner said he had
> used red and amber LED's but felt he should have gone with white
> because he thought they would be brighter.  I don't know enough about
> LED's to know if that makes sense or not, and I know some people from
> the DML have done the conversion and others sell them, so I figured I
> would pose the question here.
> 
> Thanks,
> Matt, AZ-D VeeP
> VIN 16816





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