can one visually discern between different LEDS (without powering them)

[Avidgrant]

Hi there.... this is most likely a question that is part of a series of questions as i build my first saber(s).
I have been lurking- reading- amassing parts- reading some more- and more- amassing more parts... etc for a few months now. I have learned some really cool things like why you might want to use acetone to wipe down a part before you prime it- as well as how to bake and paint the saber parts for the best results. I have also learned wiring schematics for multiple boards- and along with the fact that a guy named after a bovine disease makes cool switches. Ive scoured the inter web for lightsaber designs, and cool things that would make "mine" unique and different. As i was working on finishing one of my first sabers though- i hit a snag... 2 snags actually... other then finding a toaster over (thats the 3rd snag- but its really more of a question of what craigslist toaster oven to get).
Anyhow the 2 snags that maybe someone here could help me with are-
#1 is there a way to visually discern between the different 3 led stars that are on the website with out applying power. I am asking as during the amassing portions (which there have been many) i sort of bought a lot of these... and they don't appear to be labeled in any way... so.... i have some tri rebel- and cree both....

#2- i recently (today) discovered that dynaohms are not what i thought they were. I thought from reading that they would dynamically adjust to maintain a constant safe level output based on what they determined the led on the other side needed... bad ass.... or so i thought. I therefore figured that was way they were a bit pricy, but hey- its doing the math so i don't have to- ill buy enough for all my leds. Yeah.... apparently that is not exactly what they do. Apparently they are totally cool for accent leds- but not so much for the high power ones in the blade section of the builds. So..... is there a resistors for dummies section? Sort of a part b here- but i was looking at the page where i got some of the tri rebel (in the store). I don't see any sort of chart as to the specs of the different colors... at least nothing that looks like to me something that i can draw those relations/calculations from- but once again- maybe resistors for dummies will help.

Any assistance would be greatly appreciated. I have come really far. And getting really close here. Once i am done i will be posting my build threads- which i have been working on and will offer great detail.

Thanks!

[sgcdialler]

That's a hilariously long-winded way to refer to Madcow, and do I detect a Stargate reference?

Anyway, it's possible that there is some sort of order that the LEDs are assigned when TCSS makes the stars. That being said, red LEDs are pretty easy to pick out because they normally (in my experience) are a copper-y color. Greens and blues are white. Whenever I need to figure out which is which I use the resistance setting on my multimeter to run a small current through them--it's just enough to light them up faintly.

You're correct in discovering that DynaOhm resistors are not meant for the high-power LEDs, only accents. There is a tutorial on how to calculate resistor values and what everything means here (http://forums.thecustomsabershop.com/showthread.php?14081-Tutorial-Calculating-Resistor-Values), and multiple resistor calculators are one Google search away. As for LED stats, I've found that the quickest place to get the stats for LEDs that TCSS sells are always listed on the store pages for the custom stars. The Tri-Lux page is here (http://www.thecustomsabershop.com/Luxeon-Tri-Rebel-Star-P777.aspx), and the Tri-Cree page is here (http://www.thecustomsabershop.com/Custom-Tri-Cree-LED-P1035.aspx).

[Greenie]

Wow. That's a big wall of words ;). http://forums.thecustomsabershop.com/showthread.php?17109-Tutorial-FJK-s-quot-Down-and-Dirty-quot-guide-to-Ohm-s-Law This should help with resistor calcs. As for identifying LEDs, reds look red whites look yellow and blues and greens look white. I think powering them is the only way to be sure. If you have your chosen battery solution to hand, you can 'quickly' touch the LED pad to determine their colour. :mrgreen:

[Silver Serpent]

If you have a multimeter with a diode test setting, that will usually provide enough current to check the color on your LEDs. If you don't have a multimeter, I highly advise you pick one up. Even a cheap one from Walmart is better than nothing.

The Rebel specs are on this page: http://www.thecustomsabershop.com/Luxeon-Rebel-Star-P523.aspx Once you've determined the color of each LED die, you can look their values up on that page.

[Avidgrant]

Thank you guys... Silver Serpent- those specs on the rebel apply to the tri-rebels as well? I do have a multimeter ( bought specifically for this endeavor). I have to figure out if it has a diod test setting.......as I'm unfamiliar with it... It might as well have Egyptian hieroglyphics on it.

Greenie- yep.... Big wall of words (is there any other kind?). Thanks for the link. I will dig in there later today. Nice sabers in your sig!

[jbkuma]

If you have different color sharpies you can put a dot next to each LED to indicate the color so you don't forget. If you only have two colors and one sharpie, you can indicate the odd ball.

[Greenie]

......or you could initial the back of the star.

[Avidgrant]

these are all great ideas..... making a list of more stuff i need ....... anyone have some extra paper......... :)

[Silver Serpent]

Yes, the specs on the single Rebel page apply to the Tri-Rebel. The Tri-Rebel is just 3 of the single-die LEDs arranged on one star. Nothing more complicated than that. :)

Your multimeter may have a symbol that resembles this: https://upload.wikimedia.org/wikipedia/commons/thumb/b/b4/Diode_symbol.svg/2000px-Diode_symbol.svg.png That should be the diode test setting.

[Avidgrant]

looks like i have a mm with "diode test mode" which looks like an arrow and a +... (I think). So i will use that to test the leds! Then i will sharpie mark them- wooohooo... then i will count them up and get the appropriate number of resistors for each one. Getting there.....

[Avidgrant]

Thanks Silver Serpent!

[jbkuma]

The arrow stands for ground, which is the (-)

[Avidgrant]

OK- so i read Darth Chasm's tutorial, and if i understand it correctly- then i believe the results below are correct for working with NB3/3.7 Battery type of configuration... actually regardless of card- i believe the calculation is appropriate for 3.7V power source, but i would really appreciate it if someone could confirm so i don't go buy 50 bucks of resistors and commence blowing stuff up!
So i have a batch of many different Leds- all purchased through the store- a couple copper nova R/RB/G- and the rest are all luxeon. they consist of a combination of R/B/RB/G/W. So i did calculations for all these. Based on what i could discern from this site- the Cree reds and all cree colors- and all luxeon colors (other then red (red orange- deep red- etc)) can be run at 1000mA. Red luexon needs to be run at 700mA. So the calculations became simple (I think) as its all /1 and x1 (squared)... other then the red lux (If what i did is right).
So here is what i came up with
Luxeon
R- 1.3ohm/2.65w
B- .47ohm/.47w
RB- .5ohm/.5w
G- .47ohm/.47w
W- .6ohm/.6w
Cree
R- 1.11ohm/1.11w
G- .12ohm/.12w
RB- .29ohm//29w

I know you have mentioned you might not be able to find an exact match so you should get the next highest resistor, and i also understand from some of your posts that the higher ohm will affect the brightness- but i am a little less clear on what a higher W resister does.... does it affect battery life- drain- (is it better to get something larger here if you have the space??) efficiency ?

Thanks again for the help!

[rlobrecht]

so i don't go buy 50 bucks of resistors

Wow, that's a lot of resistors.



that the higher ohm will affect the brightness- but i am a little less clear on what a higher W resister does.... does it affect battery life- drain- (is it better to get something larger here if you have the space??) efficiency ?


The higher wattage resistors are able to disperse more current as heat. A larger one than necessary will just take up more space inside the hilt. It won't affect battery life.

[Avidgrant]

building blades for the kids, and me (:)) and some extras to mess around with.

[Avidgrant]

can you tell i like to shop at Sams :)

[TheCheeker]

The wattage is just the maximum amount of heat the resistor can disperse. As long as the wattage is greater than what you calculated, you're good. It just means it can handle what you're throwing at it. Nothing else is affected.

The resistance, on the other hand, affects brightness. You want to get the resistance as close to your calculation as possible (without going under your calculated Ohms). When calculating resistance, you're calculating the answer to the question, "How much do I have to hold back in order to push a significant but safe amount of amps to my LED?". Since Ohm's Law tells us that current = voltage / resistance and knowing your battery pushes 3.7V (or whatever depending on your battery), as your resistance goes up, the current goes down. And the brightness of the LED goes down with it.

[Avidgrant]

ah..... ok- so- is it more beneficial - assuming there is room- to get the larger w resistor? Is there a point of diminishing returns- or where it gets to a point where it has a negative effect?
Also.... can anyone check my math and confirm on the wrong path.

[Silver Serpent]

If you meet the minimum calculated requirement for wattage, you're fine. Higher wattage will not improve performance, last longer, affect brightness, or anything else other than take up more room. The only reason to get a higher wattage resistor is if those are the only ones in stock at the time.