Tri-cree stunt help

[Lazarus215]

Greeting everyone!

So this is my first saber and I've decided to dive in head first. I'm planning on this saber to be purely decorative or to be a toy my oldest daughter could mess with when she's a bit older and I may have gone a bit overkill on the setup. I'm just a little confused on some of the wiring and what the best routes are as far as buckpuck or resistors with the tri-cree setup. Here's what I'm working with...

3D Printed saber
Custom tri-XP-E2 cree star (18 degree lens)

• Blue - 3.47v @ 1000mA
• Royal Blue - 3.41v @ 1000mA
• White - 3.15v @ 1000mA

Dual 14500 Li-Ion (7.4v)
illuminated momentary AV switch (20 mA Resistor on +)
Pololu Mini Pushbutton Power Switch with Reverse Voltage Protection, LV
Possible buckpuck?

I'm not entirely sure how I should wire the LED. I'd like all the LEDs to fire at once (since I'm not using FoC) and have read about wiring them in series vs parallel, but most if not all topics I've found are including a sound card or some other power extender (not sure if I need one?) For my power source, it seemed like the best option was running 2 in series and 1 parallel without a buckpuck (just slapping a resistor on each LED die) and after watching a video from Genesis Custom Sabers, I'm still just a bit confused on wiring the 3 for non-FoC applications...

I'm basing the main wiring off of JediXIX's diagram Here

So my main questions summarized are...
Is the 7.4v powersource sufficient for the tri-cree setup?
For my build, would series or parallel setup be better? (if running 2 blue dice parallel with a resistor and the white separate, would a buckpuck be preferable for the white? or is that overkill?)
Could someone either point me in the direction of, or drop a wiring diagram for series/parallel wiring for tri's?

I'm probably going to end up gutting the 3D printed hilt later when I buy a machined one, so I'd like the wiring to be as... applicable? as possible (meaning I dont want dim LED's for when a blade gets put on)

Thank you in advance!

[Lazarus215]

Figure I'll throw in some diagrams to help my god awful wording...


This is showing how I imagine a buckpuck set up will go (in series)


Dropping the buckpuck and putting in a 4.7w 4.7ohm resistor on the LED series


Wiring the LED in parallel with a 2w 1ohm resistor on each +lead to the LED

Are any of these fine? whats wrong with them if they are wrong? which would get the best brightness or best battery life?

[Silver Serpent]

Some issues:

1. Wiring is correct, but there's not enough voltage. With all three LEDs in series, that's around 10v +2v for the BuckPuck itself. You'd need a power supply capable of providing 12v or more.
2. Again, insufficient voltage. A 7.4v pack will not give the necessary 10v to run those 3 LEDs in series. Not sure how you calculated that resistor.
3. Wiring is correct, but you're using the wrong resistors. The 1 ohm, 2 watt resistors will work for a 3.7v battery pack, but they're too small for a 7.4v pack. Your LEDs will blow up.

The easiest and most cost effective solution is to go with diagram 3, and calculate new resistor values, OR use a 3.7v pack with the current resistor values.

[Lazarus215]

Okay, it looks like I read my notes wrong... the 4.7w 4.7ohm resistor would get stuck on each of the LED's. If I left the white LED unwired and put the RB and B in series, how would I calculate that forward voltage? If that will require a smaller resistor, I'm all for it. those 5w 4.7ohm resistors are beefy.

Thank you for the help Silver Serpent!

[Silver Serpent]

In series, you add the forward voltages of your LEDs together. Current remains the same. Blue + Royal Blue in series is calculated as 3.47 + 3.41 = a single LED running with a 6.88V forward voltage @ 1000mA. Plug those values into your resistor calculations and you'll get an appropriate resistor.

The 4.7 ohm 5W resistors would work fine for the parallel wiring setup (diagram 3)

[Lazarus215]

So plugging in 7.4v power supply, 6.88v forward voltage, and 1000mA forward current, its telling me It'll need a 2w 1ohm resistor. The wizard is also spitting this out.

"The wizard thinks your forward voltage spec is suspiciously high, but will proceed with the calculations. Please double-check your specs."

[Silver Serpent]

Yeah, there aren't any single LEDs with a Vf in that range. That's just how the math works. The resistor you calculated will do the job.

[Lazarus215]

Excellent. Thank you very much for the help and clarification.

Here is the final diagram then for anyone who comes across this...


2 LED series


triple LED, large resistors

[Silver Serpent]

I missed something in that series-wired diagram. I'mma blame it on insufficient coffee this morning.

Don't connect the Royal Blue + and - pads to each other (purple wire) or the Blue + and - pads (light blue wire). The green wire connecting Royal Blue - and Blue + should stay.

[Lazarus215]

gotcha, all updated and noted. Thank you again for the help!