Who is the LED expert out there?

[TAftonomos]

I've got some questions concerning an idea of mine, and would like some input from the LED experts out there.

[ducatiz]

I've got some questions concerning an idea of mine, and would like some input from the LED experts out there.

do you mean LED expert as in desiging an LED or expert as in installing/designing an array?

i've made a few projects (brake and turn lights) with LED arrays, I can explain how to set them up but I can't help you with designing the buggers themselves.

[Bill in OKC]

I studied them in school...  They work just like normal diodes - with the added quality that they emit light. 

[TAftonomos]

Trying to figure out if a single row of them, sunk into the small lip on the back of the seat cowl, will be bright enough for a brake light/running light.   With the new exhaust system I'm working on, there is no real place to put a taillight that looks integrated with the bike.

[Bill in OKC]

That sounds really cool.  I've seen custom Harleys with tail lights molded in.  I guess that I am not that much of an expert.  The specs should be published by the manufacturer and there should be ?DOT? specs on how bright a tail light must be.  Are you thinking two levels of light?  The new high bright LEDS are new since I was in school -  My Rizoma turn signals have three different sizes of LEDS in the array.  The LEDS that I am familiar with only have one 'proper' biasing - which means only one light level when forward biased.  Some LED packages have two LEDS built in, two colors depending on the direction of current - so *maybe* it is possible that there are LEDs with two levels of brightness.  Otherwise I'm thinking you would need a dimmer array of LEDs for normal taillight use and a second brighter array for the brake light in the area you have available.  They sell replacement bulbs that used LEDS instead of a filament - so I'd think if you used that style of LED you would be covered as far as brightness

[ducatiz]

for LEDs, bright ≠ viewable

a brake light is more a beacon than a spotlight.  that's why you only need about 30-40 cp as it is omnidirectional.

i've seen LEDs with excess of 100 cp but they are unidirectional, so if you are not in the line of emission, you can barely see it.

check out the new cars with LED brake lgihts, they have a thick diffuser to make the bright LEDs omnidirectional.

[Bill in OKC]

Yeah, it might be hard to make it viewable from the side.  Again - how far to the side is necessary?  The stock taillight is kind of shrouded by the beer tray from the side but it is probably still somewhat visible from the side.  I guess if the LED array continued around the sides some then it could work.

[DarkStaR]

Just a thought...

http://pakbikes.net/PS1000LE/FLEDA001.html

[TAftonomos]

The FLEDA is neat, but the back side of the monster cowl isn't flat, it's got the half moon shape.

Other though, so I could add more LEDs, was to get a carbon cowl, and fill in the area in the back so it is flat.  Then I can have several rows, perhaps 2-3 full length. 

That might be a better option.  The top of the can is flat, and the outlet of the can is pretty much where the tail light sits now.  This is of course where the can needs to sit, to tuck up as far as it can.  Otherwise it hangs down to far to be aesthetically pleasing.

I could, of course, just go with another seat.  Something with the lights integrated into the tail might work. Hmm...1098 perhaps?

[Bill in OKC]

Here is something I found.  http://www.aerostich.com/catalog/US/Stopper-LED-Brake-Light-p-16981.html
The VERSA version is not pictured - unless they look the same but it would be interesting to see if the Versa is one row or two.  It sorta looks like it might be DOT approved...  A lot of these things look like they just turn on an extra set of LEDS for the increased light.  You could alternate LEDs - every other one off until the brakes are hit - then maybe you would only need one row of LEDs?  I wonder if the VERSA version has a way to change the brightness of the LEDS - at any rate it looks like it is possible to make at least a brake light with one row of LEDs.

[He Man]

As stated above, they are prettymuch unidirectional. I think the viewable area of that bright light is about 7degrees or so. you can barely see it from the side.

I run the clearalternatives LED board with the integrated light. You can barely see it unless your on another bike directly behind me. My riding friends tell me they cant see it from the lane over behind me unless is pitch black outside.

Maybe SMD LEDs are a better choice? the same stuff used on those vizzi tech boards. they are a pregnant dog to solder though since they are so small.

[cbartlett419]

http://www.ledsupply.com/

I'm not sure if this is helpful, but I have ordered from here. The tech guys are knowledgeable and patient.

[Louv]

One way to help make the LED's light omnidirectional is to use a "Light pipe".

Take a look at late model BMW (the cars, not the bikes) rear lights.  They feed LED light into a curved, textured plastic "pipe"  (it's not really a pipe, since it isn't hollow... it's actually a rod... but I digress)  That might be the effect you are looking for.

You can experiment with light pipes by going to TAP Plastics and getting a 1/4" acrylic rod
http://www.tapplastics.com/shop/product.php?pid=148&

You'll need to "texture the rod to cause some of the light to refract and reflect out of the pipe.  Textures can be shallow cuts, ridges, etc.  The rod can be bent using careful application of heat.  (see the Tap Plastic website for more info)

Point the LED into the ends of the rod. 

(not affiliated with TAP plastics, BMW, or any LED manufacturer... just a consumer of all three)

[dbran1949]

The texture can be as simple as sanding, but bead blasting give a nicer look