LED Engin and NB

[Jenny]

So, I'm looking at the Plecter Labs page, and it does list the LED Engin as one of the LEDs the Nano Biscotte is compatible with. And, as I understand it, the LE with all 4 dies lit would be the brightest LED on the market currently, right? So... when wiring the NB to the LE, does one simply wire the 4 dies in serial? And to do that, would one wire the positive from the board to die 1's positive, then d1+ to d2+ to d3+ to d4+, and the same with the minuses, or does one go board positive to d1+, d1- to d2+, d2- to d3+ and on around like that?

[Silver Serpent]

There's not really a single answer to that question. You can wire them all in series, but you end up requiring a fairly hefty voltage to power the LED. Up to 20+ volts for a green LEDEngin. You could also wire them all in parallel, but you need a minimum of 4000mA to drive the LED to its proper potential.

Many of us wire them in "seriallel," which is 2 dice wired in series, and the other 2 dice wired in series, then wire both pairs in parallel to each other. You only need 2000mA of current, and the voltage is only double what a single die would be.

LEDEngins are *some* of the brightest on the market. There are others which are brighter, but they have a new set of difficulties with being use in lightsabers. Check out some of Sunrider's sabers if you want to see them in action.

One other thing to be aware of: the LEDEngins love power. To run most of them in seriallel, you need TWO li-ion batteries. The Nano Biscotte is designed to use ONE li-ion. You'll have to do some creative wiring in order to get sufficient power to the LEDEngin, without blowing up your NB. The Petit Crouton is designed to run on two li-ions, and is much easier to use with LEDEngins. Just something to think about.

[ZacMuleer]

Hey SS -

What if you only use two of the dies in an LEDEngin in serial with the NB? Would the single li-ion be sufficient?

[Johannes Huber]

Correct me if I'm wrong, but there is also a maximum amount or current that can go through a given board (as well as a max voltage). I seem to recall there is a max of 2000mA through the NB and I am not sure of what the max is on the PC. There is also a limit on how much current the various batteries can output at a time. I think that the 14XXX are limited to 2000 mA and the 18XXX are somewhere around 5000 mA. All this, if I understand it correctly, would also figure into what types of LED are optimal for what setup. If someone with more experience could check these and correct me if I am wrong, it would be much appreciated. On the LEDs, I will say that I am building a saber right now using an NB with a 4.8V nimh battery pack and all dies active warm white tri-rebel LED and it gets quite bright, so this may be an alternative to the LEDEngin that is worth exploring. I've also worked with the quad rebels and they are very bright and very easy to set up although I do not know if they would be optimal for the NB, if the max current is 2000mA (It would, in parallel, divide the current among all 4 dies to about 650 mA and they can take a lot more. At 1500mA, the cool whites are... impressive, if way overdriven)

[Silver Serpent]

When you wire two or more LED dice in series, you add their forward voltages together. For instance, if you had two dice at 2.5v each wired in series, then the combined forward voltage would be 5v (and would not work with a single 3.7v battery).

Forward voltages vary by bin number and color. Without more information about your particular LEDEngin, I cannot give you a definite answer. Since I am not aware of any LEDENgins with an individual die Vf of 1.85v or less, I doubt you'll be able to find a pair of LED dice that total 3.7v or less in series.