Purple!

[Maleficia]

So, I've read a lot of threads regarding various ways to set up LED's for a purple blade, but considering I have zero experience with this kind of thing, I'm still very much lost. My original plan was simply to use a white Luxeon Rebel Star with a purple filter, but if at all possible, I'd like to try and go for an RGB mix or some such. I'm going to be acquiring a pre-wired Nano Biscotte soundcard and a 2 watt bass speaker running off a single 3.7v li-ion cell, so what would be my best option in terms of possible LED solutions? And does anyone have a wiring diagram or a tutorial on how to resistor said LED to get a nice purple? Bear in mind that I have no idea about any of this wiring in parallel vs in series stuff, so please be gentle and treat me like the uber noob that I am! *lol* I know enough to get the board and speaker wired up, but I still haven't figured out any of the more advanced LED tricks yet... hence my original plan to use a simple white LED with a filter. Help?

[Silver Serpent]

If you're going to use the NB and a single li-ion cell, you will NEED to run the RGB in parallel. Best recommendation is the tri-rebel RGB.

http://en.wikipedia.org/wiki/Parallel_wiring if you wanna read a bit. I can give you a quick description though.

Take the red wire that runs to your main LED and solder a splice into it, so that it forms a "Y" shape. Take one of the top arms of your "Y" and run it to the positive terminal of your Red Die, and take the other arm of the "Y" and run it to the positive terminal of your Blue Die. You will do the same for the black wire. Make a "Y" with the black wire, and connect the top arms to the negative terminals of your Red and Blue LED dice.

To get a nice purple instead of a pinkish color, you will need to put a resistor on the line with the Red LED. It can go on the positive side or the negative side. I can't give you an exact value. It's something you'll have to play around with to get the shade of purple you're looking for.

[Maleficia]

If you're going to use the NB and a single li-ion cell, you will NEED to run the RGB in parallel. Best recommendation is the tri-rebel RGB.

http://en.wikipedia.org/wiki/Parallel_wiring if you wanna read a bit. I can give you a quick description though.

Take the red wire that runs to your main LED and solder a splice into it, so that it forms a "Y" shape. Take one of the top arms of your "Y" and run it to the positive terminal of your Red Die, and take the other arm of the "Y" and run it to the positive terminal of your Blue Die. You will do the same for the black wire. Make a "Y" with the black wire, and connect the top arms to the negative terminals of your Red and Blue LED dice.

To get a nice purple instead of a pinkish color, you will need to put a resistor on the line with the Red LED. It can go on the positive side or the negative side. I can't give you an exact value. It's something you'll have to play around with to get the shade of purple you're looking for.

This is exactly what I was looking for. Thanks!

One more thing, and this may be a stupid question, but I'm assuming I'll still need a resistor to regulate the current from the board to the LED as described in the manual, with the value depending on the typical calculation?

[Forgetful Jedi Knight]

Yes. If you wire in parallel, each die would need it's own resistor, and the values would be different and the red would need a resistor of bigger value.

[Maleficia]

Yes. If you wire in parallel, each die would need it's own resistor, and the values would be different and the red would need a resistor of bigger value.

Aha! So if I'm understanding this correctly, I'd be using two dice (red and blue), which would require one resistor each, plus the "bigger value" resistor on the red die as described above for a total of three resistors? Would the two "main" resistors on the red and blue dice be of the same value?

[Darth Nater]

Two resistors. One for Blue, one for Red. The red will require a larger resistor to tone it down since it will overpower the blue. They say "no certainty" because the values will differ depending on the led and power source. The following by no means will translate directly to your build, but can serve as a half a$$ed explanation.

I have one saber that uses a cheapo Obi-wan soundboard running off a 6volt power source (4AAA). Well, actually I just switched this out to a 7.4 lithium ion setup but no matter, that board has to be setup entirely different and likely runs around 5V anyway. Regardless, for my setup using a Dealextreme cheapo RGB from China, I have it parallel with a 1watt/4.7ohm resistor on the red and I think a 1watt/1ohm resistor on the blue. I got on mouser.com and bought like 2 each of various little 1 watt resistors and played around with it til I got the shade I wanted. They are like 17-50 cents each so no bank breaker. Could have used a potentiometer but couldn't find one that was 1 watt and while tedious, this seemed easier to me. And aside from when I built the saber, I'm never involved with this kind of thing.

Your setup would be much different with a NB board sending out more juice to the LED that my setup is with the $20 toy saber soundcard is, and depending on what LED you used, that would change as well. For the little setup I have on this saber it comes out a decent purple.

My other purple is out of a 7.4 source through a PC board and an LEDEngin RBGA. The PC of course regulates the current and it doesn't need a resistor for this, but for one reason or another, I have it wired in series and it comes out perfect. I would have thought the red would overpower without being resistored back, but it doesnt in this case.


Aside from my rambling, the short answer was 1 resistor for the blue die and one for the red. The red will need to be resistored more(larger resistor) since red will suck current and overpower blue. This prevents the pinkish. The larger the resistor on red, the closer to a purply blue it will get. The smaller the resistor on red, the more pinkish it will get. When the batteries get low, it will get a lot closer to pink as the red will suck up the power.

[Maleficia]

Two resistors. One for Blue, one for Red. The red will require a larger resistor to tone it down since it will overpower the blue. They say "no certainty" because the values will differ depending on the led and power source. The following by no means will translate directly to your build, but can serve as a half a$$ed explanation.

I have one saber that uses a cheapo Obi-wan soundboard running off a 6volt power source (4AAA). Well, actually I just switched this out to a 7.4 lithium ion setup but no matter, that board has to be setup entirely different and likely runs around 5V anyway. Regardless, for my setup using a Dealextreme cheapo RGB from China, I have it parallel with a 1watt/4.7ohm resistor on the red and I think a 1watt/1ohm resistor on the blue. I got on mouser.com and bought like 2 each of various little 1 watt resistors and played around with it til I got the shade I wanted. They are like 17-50 cents each so no bank breaker. Could have used a potentiometer but couldn't find one that was 1 watt and while tedious, this seemed easier to me. And aside from when I built the saber, I'm never involved with this kind of thing.

Your setup would be much different with a NB board sending out more juice to the LED that my setup is with the $20 toy saber soundcard is, and depending on what LED you used, that would change as well. For the little setup I have on this saber it comes out a decent purple.

My other purple is out of a 7.4 source through a PC board and an LEDEngin RBGA. The PC of course regulates the current and it doesn't need a resistor for this, but for one reason or another, I have it wired in series and it comes out perfect. I would have thought the red would overpower without being resistored back, but it doesnt in this case.


Aside from my rambling, the short answer was 1 resistor for the blue die and one for the red. The red will need to be resistored more(larger resistor) since red will suck current and overpower blue. This prevents the pinkish. The larger the resistor on red, the closer to a purply blue it will get. The smaller the resistor on red, the more pinkish it will get. When the batteries get low, it will get a lot closer to pink as the red will suck up the power.

Awesome! Your rambling definitely helped.

Have I mentioned how awesome you guys are lately?

[Yoshi-Taka]

My other purple is out of a 7.4 source through a PC board and an LEDEngin RBGA. The PC of course regulates the current and it doesn't need a resistor for this, but for one reason or another, I have it wired in series and it comes out perfect. I would have thought the red would overpower without being resistored back, but it doesnt in this case.

The PC's regulation you're referring to is the Drive setting in the Config, right? The NB has a Drive setting as well. Wouldn't such a setup (with the 3.7v battery instead of the 7.4v, obviously) be just as plausible? Meaning the RBG LED could forego resistors and use the Drive setting to regulate the dice? I would think that wiring them in parallel and using the Drive setting to maintain it without overdriving the dice would be safe but I haven't been able to try it yet and I don't wanna screw up a LEDengin or Tri-Rebel without being sure.

I ask [besides the relevance] because I'm trying to get the multi-die LEDs figured out for myself as well. I personally don't mind dealing with pink [I'd rather have pink than purple anyway] if that's the price for not using resistors.

[Darth Nater]

Pictures are hit and miss, but if you can see my profile I have a couple of the purple ones in there and how they turned out. Sometimes pictures make something that looks good in person look dull and other times they make something look a lot better than it really is. The pic with the pair of purples, the one on the right is the cheapo board and DX cheapo RGB off 6V. The one on the left is the PC board and Ledengin. Its brighter and uses a clear blade with giftwrap where the other is in a trans-white blade with giftwrap. They look pretty close to the same in the picture though, but you can tell the difference in person. Gives you an idea of what different things will look like though (boards, batteries, blades, LEDS).

I have zero experience with any of this stuff aside from when I built these sabers and digging up all of the necessary information and trying to understand it all from scratch was a tedious experience. Its out there though, and while "do a search" is a tired a$$ thing to hear in my mind, sometimes it ends up being the only way. I found most of my info on wiring the LED on a different forum actually. Got told to "do a search" a few times along the way, and almost became discouraged but managed to maintain. The one thing I will say that helps the most is if you ever find something with some info that you will need.. BOOKMARK IT. You will need it later and will not want to have to try and find it again. I have about 5-6 bookmarks still on my browser from when I did that first purple. And I have had to revisit them a couple times since then.

Two final things I learned with the purple as well. 8.7 degree lens is about perfect on a regular style LED. 5% doesn't mix as well. For a Tri-Rebel, I have no clue. I guess just whatever is available. Clear blade looks better than a white blade for a mixed RGB as well, and for me, I ditched the white diffuser that it came with and loaded it down with about 6-8 feet of cellophane giftwrap. Made a difference.

[Darth Nater]

I don't think the NB regulates current. I haven't paid much attention to it because I'm not in the market for a board, but I was pretty sure that it requires resistors to the LED.