The Guide for a Perfect RGB Light with PMMA fiber optic cable

Hi Mr Nozzle,

The LEDs are surface mount and have got a large pad labelled as THERMAL. I have added a large copper area to the board to dissipate the heat. I have felt the heat that the Luxeon star diodes give out, and I find it hard to believe that my bit of copper will be up to the job, but its bigger than the heat sink area on the suggested PCB pad on the diode datasheet, so it should be ok.

I also intend to machine an aluminium plate that the PCB bolts down to, and this plate will support another component which will hold the fibres in the right place. This plate will help with the heat too I am hoping, even though its on the other side of the fibreglass to the diode.

I really hope this works!

By the way, you can use T Cut to polish the ends of the fibres....


Pete.

Hi Everyone,

The luxeon Rebel surface mount diodes arrived today, along with some 12 degree lenses, so I have been busy putting it all together.

I designed a circuit board that holds all four diodes (RGBB) and there is a large area of the board that is just there as a heatsink. I put the board flat down against a heat sink so that any extra heat that goes through the board can get to the heat sink and dissipate. Strangely, the diode does not make much heat, and the copper area of the board does not really get very warm.


The diodes

[img][/img]
The board with the lens stuck on over the diode




The diode lit. I am running it off an LED driver in series with another diode (standard Luxeon Star - its blue and you can see it glowing under the heatsink in this pic). The bench supply is only saying the whole thing is drawing 600ma, and the rebel is 1000ma, and the star is 600. I think the driver is limiting current some how, so I suspect that the diode is capable of being even brighter than this, as its only drawing a third of the current its supposed to. This pic was taken in broad daylight, the camera stopped itself down.


A tight spot of light on the celling. Hopefully the tight angle will help get more light into the fibre. The diode on its own is 140 degrees, the stick on lens takes it to 12 degrees.


Looks promising, I am going to go and try powering the diode direct without the driver and seeing what happens. It may well explode as I have no current limiting resister installed yet.

Looks good, iam not shure your cooling bads are big enough, but you will see how long it will runn. When you go to 1000ma, heat will burn extreme, be carefull.
Let us know more if you have further success. Good luck ...

The datasheet has a recommended pad layout including the heat sink area, and mine is twice the size of theirs, so hopefully it will be OK. At the moment, i cant work out how to drive the diode at 1000mA, I have connected it direct to the PSU and it still only takes 500....

so it apears its not a 1000ma led, just a 5ma, maybe its bright enough like this? you will see it when attach it to a nozzle.

No, its a 1000mA diode, the guy from lumileds says im not giving it enough whelly. He says that it dosn't matter what voltage it is, aslong as the current is enough....

Just got 4m of 3mm jacketed PMMA from fiberoptic.ch

Good service, fast delivery even to the UK - just a few days.

Thanks a lot fiberoptic.ch :-D

First off I have too say all of your projects have been awesome to learn and read about. I have been working on one of my own and I'm at the stage of adding light to it. I have a question I'm using the DIY driver from here http://www.pcboard.ca/kits/led_rainbow/ . I will be using a red, blue and green Luxeon Rebel stars. From what I have been reading I will need a current limiting resister I have a set of 1.8 ohm 2 watt one to use will these work or will I need bigger?

Hi, the rgb conteroller looks ok. Resistor, It appends on the led you are using, on how many mA they need for full power.
I recomend not to use a resistor together woth PWM, use this http://www.roboternetz.de/phpBB2/konstantstrom.php constant power suply, easy to build.
Have fun an d good luck.