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View Full Version : Lux III, K2, V... a distinction on lumens, current, etc.



Novastar
06-11-2007, 04:08 AM
OK... I want to help get this straight.

1. If an LED is rated at 'X' lumens--it will only reach that rating if you drive it at its "ideal" current (or thereabouts), which is called "max continuous current" in the case of the luxeons. Simply purchasing an LED rated at 'X' lumens... DOES NOT GUARANTEE THAT YOU WILL BE SEEING 'X' LUMENS WHEN YOU CONFIGURE IT!

2. "Lumens" are over-rated anyhow. Just because (let's say for example) a blue Lux III LED shows "30 lumens" at 1A, and a red-O Lux III LED shows "190 lumens", does not really mean that the Red-O is what you would expect... meaning SIX TIMES BRIGHTER!!! Holy crud. Imagine if it was. You'd never hear the end of it. Especially from Darth Vader or Darth Maul. They'd appear in ghost form, and tell you that "RED IS BETTER". :twisted: "BECAUSE... GOOD IS DUMB".

But... alas. You don't hear that. Vader does NOT show up when you're in your undies snacking on pringles watching EP I. That's because the Lux III red ISN'T six times as bright as the Lux III blue. Lumens are actually pretty stupid in divining brightness FOR OUR PURPOSES.

After we: put the LED in a metal hilt (so it is no longer out in the "open"), throw some optics over it, drive it to full blast into a tube with a diffuser and then send back some light with a mirrored tip all the while driving some sound through a speaker... not to mention some of the light getting diffused by the polytube also... well... a clinical, non-LED-saber-related term like "lumens" is PRETTY bloody far from any of your main concerns wouldn't you say? 'Nuff said.


3. Take the keys and drive your LED nuts -- Ah, vehicles get you to your destination much easier--and much more efficiently! Toyotas are nice, but a Corbin, Plecter or Ultra is better!

Think of a resistor... as a junky bicycle. I mean, yeah... it's cheap... but not very efficient, huh? You waste a LOT of energy pedaling, right?

Driver boards that regulate the CURRENT going to the LED are most ideal to get the maximum performance from your LED. You don't have much choice if you want maximum results anyhow--because if you can't control the current (i.e. resistor or Force FX)... then you have a car with no driver and you have a problem, don't you? If you want control & efficiency... you need a car... in the form of a driver.

Alright. If I'm totally wrong, please add, correct or whatever to this thread. I'm only hoping to help those who aren't certain about what LED to choose and why for their battery/driver setup.

Onli-Won Kanomi
06-14-2007, 11:54 PM
I've been wondering about all this too...as a newb [please dont shoot! :lol: ] to 'DIY' sabers I've been reading through as many posts as I can here but it all gets very confusing...

From what i understand [or maybe misunderstand?] using LED lumens ratings as a measure of potential brightness for use in sabers is most useful within a colour group of LEDs rather than between them because some colours are more easily perceived by the eye/brain than others so PERCEIVED brightness of those colour LEDs can SEEM 'brighter' even when they actually emit lower lumens?

So a 80 lumen red would be dimmer than a 160 lumen red but a 140 lumen green would be PERCEIVED brighter than even the 'higher' lumen red because its easier seen by the human eye?

Did i get that much [more or less] right?

So if you want maximum brightness you not only have to consider the lumens but the colour you want to use?

Which is easier for would-be Jedi than for would-be Sith I guess who are limited to one colour.

All this makes me think that maybe the future of saber brightness might be in clustering multiple LEDs together like in AceRockets Tri-Lux or my [probably impractical] idea of a 7-rebel cluster?

Especially for those limited in colour choice [Sith] this would seem the best way to get brighter sabers???

But all that depends on as you say the presumption that youa are getting the most brightness the LED is capable of to begin with and this where a newb like me gets especially confused...I dont want to 'underpower' whatever LEd I use so it's less bright than it could be and all the different lumens ratings and forward voltages and battery configurations and driver maximum amperage capabilities gets VERY confusing...

Say for example do i want to choose a Ultra board over a Plecter Board or vice versa...does it make much difference that one can drive 1500 mah
and the other 'only' 1300? maybe it makes more of a difference with some LEDs than others?

All very confusing to a newb...so I keep reading here trying to figure it all out instead of ordering which doesnt do TCSS store any good [sorry]...yet...

Lux III [which arent all really 3 watt some are 5?] Lux V [which are all 5 Watt? and want more voltage and less amperage?] K-2 [which want less voltage and more amperage?]...

And then there's hilt length...Lux Vs can run on a 9-volt battery...sounds good if you want to build a short hilt...but wait maybe not because a regular 9 volt isnt powerful enough you need lithiums??? And still it doesnt have much run time so you need rechargables which make the hilt longer so you might as well use a K2????

I keep reading and reading here and only get more and more confused..it is all enough to make my head spin like Linda Blair... :lol:

Novastar
06-15-2007, 01:10 AM
"ONE BASE ATTA TIME!!!" -- Costello from Abbott & Costello's 'Who's on First' skit...

Lumens measured within their OWN color range.

Yes, I agree. 80 lumens of red vs. 160 lumens of red... you will notice the difference. As to mixing apples and orange of red vs. green or whatever--you won't really be able to tell unless it's a huge lumens difference--such as 30 lumens of green vs. 190 of red.

"Maximum" brightness.

Again--this is relative to many factors--even the bin of the LED itself! Basically, shoot for what fwd v and current the LED "wants". That's a good "default". If you want to get creative... slightly "overdrive" it (if it wants 700ma, you could overdrive to 1000ma for example--Corbin has done this with a Lux V in the Killer Penny saber! That's one stellar lookin' hunk-a brass n' copper...).

Ultra board vs. Plecter

They are two different pieces of hardware, and I can't compare them anyhow since Ultra's board is not physically "out" yet. Soon though. What I *CAN* say is that both boards can spit out up to 1.5A. BUT... this only means that they can handle LEDs that even WANT 1500ma!! Lux V's don't want 1500ma. They want 700ma.

Moral: MORE mA IS NOT NECESSARILY BETTER! GIVE THE LED WHAT IT WANTS, DANG IT!!!!!! HAPPY LEDS!!! NO SAD LEDS!!! YOU ONE-EYED FREAK... ;)

I'm teasin'. Get over it. heheh

"3-watt" vs. "5-watt"

Forget you ever heard that for now. There is basically only Lux I, III, V, K2, Rebel (in terms of Luxeons). The wattage is the heat produced via the entire circuit (batteries are providing that possibility for heat!!!) and that can vary. And, it's not important unless you're planning on pushing a heatsink to its limit by like... saying "gee, I guess I'll BARELY leave enough surface area to just BARELY cover the heat." Bad idea.

To extrapolate a bit more... for example... a Luxeon III Red-Orange is quite capable of "producing" 5 watts of heat energy. Although in theory, it's not the LED doing this, it is the battery/power source.

Another thing to know... sadly, LEDs are like 80% heat and 20% light... despite their efficiency in terms of brightness to power consumed/used. Which is why they need to be "heatsunk" when the amps start climbing...

Hope it helps! 8)

Eandori
10-08-2007, 01:42 PM
Hey Novastar, great post! You do a fantastic job spreading the knowledge to all saber smiths out there. The entire community definitetly benefits from efforts like this one. I've made some minor corrections/changes. Listed below in bold text.

=============================================
Lumens measured within their OWN color range.

Yes, I agree. 80 lumens of red vs. 160 lumens of red... you will notice the difference. As to mixing apples and orange of red vs. green or whatever--you won't really be able to tell unless it's a huge lumens difference--such as 30 lumens of green vs. 190 of red.

With an unfocused, open Luxeon LED I agree. It's harder to tell which one is brighter. But my experience has been... when I get that LED behind an optic, and shoot all that light into a well dispersed blade it becomes a lot easier to tell differences in how much light is coming out. To be more specific, among my electronics tools is a regulated power supply. If I connect it directly to a Luxeon LED in a blade, I can VERY clearly see the brightness difference when I ramp up the current slowly.

My Green luxeon K2 (130 lumen at 1.5A) was visibly dimmer then my Green Luxeon V (160 lumen at 700mA) and quite a bit dimmer at 1 amp on the Lux V.

"Maximum" brightness.

Again--this is relative to many factors--even the bin of the LED itself! Basically, shoot for what fwd v and current the LED "wants". That's a good "default". If you want to get creative... slightly "overdrive" it (if it wants 700ma, you could overdrive to 1000ma for example--Corbin has done this with a Lux V in the Killer Penny saber! That's one stellar lookin' hunk-a brass n' copper...).

2 factors here, every color spectrum has a frequency band where the Luxeon LED puts out the most light. So you want one that is close to it's peak frequency for that color.

The other factor is for each individual LED, there's a point where adding more current does not really make it much brighter. Or a point where so much power is running through the LED it will fry soon. Some LED's will happen to be more sturdy then others. Problem is, there is no good way to safely test that. When your LED burns out, you pushed it too far.

I would say... start at the rated current for that Luxeon LED. If you feel risky and want it brighter, crank it up in increments of 10% at a time. I would personally stay away from doubling the current, but I could see going as high as 150% the rated current.

Ultra board vs. Plecter

They are two different pieces of hardware, and I can't compare them anyhow since Ultra's board is not physically "out" yet. Soon though. What I *CAN* say is that both boards can spit out up to 1.5A. BUT... this only means that they can handle LEDs that even WANT 1500ma!! Lux V's don't want 1500ma. They want 700ma.

Moral: MORE mA IS NOT NECESSARILY BETTER! GIVE THE LED WHAT IT WANTS, DANG IT!!!!!! HAPPY LEDS!!! NO SAD LEDS!!! YOU ONE-EYED FREAK...

I'm teasin'. Get over it. heheh

No driver board is brighter then another IF they both can supply enough current to the LED. If one board gives 1.5A and so does another, they drive that LED exactly the same. The same current value from different sources will yeild the same result.

Now...

What differentiates one driver board from another is the OTHER effects you get. How well it handles input voltage (upconversion?, downconversion). What kind of sound/light effects it adds. How much power does it use. Etc. Erv's board putting out 1 amp of solid current is 100% exactly the same as a resistor putting out 1 amp for LED brightness.

"3-watt" vs. "5-watt"

Forget you ever heard that for now. AMEN, thank you!! There is basically only Lux I, III, V, K2, Rebel (in terms of Luxeons). The wattage is the heat produced not produced... consumed by the entire circuit via the entire circuit (batteries are providing that possibility for heat!!!) and that can vary. And, it's not important unless you're planning on pushing a heatsink to its limit by like... saying "gee, I guess I'll BARELY leave enough surface area to just BARELY cover the heat." Bad idea.

To extrapolate a bit more... for example... a Luxeon III Red-Orange is quite capable of "producing" you mean consuming :) 5 watts of heat energy. Although in theory, it's not the LED doing this, it is the battery/power source. Right, the battery is producing exactly what the circuit is consuming. The lower resistance your circuit has, the more current comes out of the battery with a slight voltage drop. Power = voltage times current. So a 7.2v battery putting out 1 amp is 7.2 watts. And a battery being "pushed harder" voltage dropped down to 6.8v but now kicking out 5 amps of current for a total of 34 watts of power.

Another thing to know... sadly, LEDs are like 80% heat and 20% light... despite their efficiency in terms of brightness to power consumed/used. Which is why they need to be "heatsunk" when the amps start climbing...

Anytime you deal with heat, be sure to look at the power dissipated (voltage x current). Power... is what causes the heat. 100 amps at near 0 Ohms is effectively a wire and does not heat up. 10,000 volts but 0 current is an open circuit. Again, no heat generated. You need both voltage AND current to get power... and create heat.

Hope it helps!

xwingband
10-08-2007, 02:12 PM
Erv's board putting out 1 amp of solid current is 100% exactly the same as a resistor putting out 1 amp for LED brightness.

The rest is good but I have to pick on that... :P

Not really. A PWM driver is constantly over and underdriving the LED to maximize battery life and brightness. Under PWM the LED is actually off 15% of the time it's "on".

Plus, a driver gives it exactly what it wants... if you happen to have a low Vf LED then you're over-resistoring the LED, etc... granted most resistor aren't exact anyway. Usually values are rounded up to the next most available resistor.

EDIT: Visually is there going to be a difference? I don't know but if anything it's small, so not 100%... maybe 90% or something. I guess it's like comparing cars though, a sports car and budget sedan will both get you going 80mph but of course the sports car is a whole 'nother ride. :wink:

erv
10-08-2007, 09:37 PM
Erv's board putting out 1 amp of solid current is 100% exactly the same as a resistor putting out 1 amp for LED brightness.
Not really. A PWM driver is constantly over and underdriving the LED to maximize battery life and brightness. Under PWM the LED is actually off 15% of the time it's "on".


Not true. That's not because a driver is run by a PWM that the current is chopped. That's the way you do it when you are in first year of electronic engineering school :wink:
My driver is a current regulator. It's true that the control is PWM, but current is smoothed afterwards, and the voltage applied to the luxeon is pretty constant (with little ripple, that's all). It's not like I have Vbatt fully applied to the luxeon during 15% of the PWM ON time. The luxeon is not overdriven in anyway with this technique, except if you set a current higher than it's suppose to be run at, like 1.5A for a red lux III while it's supposed to take 1.4A max.
And then for the difference it makes, people are most of the time living/wishing in a fantasy land... your eye can barely make the difference between 1.4 and 1.5A. Lumen are not increasing in a linear way with current, once you've passed the forward voltage of the LED.

Erv'

xwingband
10-09-2007, 06:54 AM
Okies... I stand corrected. That is definately how I've heard Corbin describe his driver though. He said it averages out to what it's supposed to in the end...

erv
10-09-2007, 11:03 AM
Okies... I stand corrected. That is definately how I've heard Corbin describe his driver though. He said it averages out to what it's supposed to in the end...

yep, right on the money. Just like a capacitor smoothes a voltage, a coil (inductance) smoothes the current, that why it ends as a stable voltage / current to the luxeon (except the ripple, which depends on the quality of the parts used, how big the coil is and the current being taken by the load)

Erv'

DACOTA
10-09-2007, 12:52 PM
Heehee, he got burned, but I've been char-broiled. :wink: :lol:
Btw, just kidding x-wing. But I couldnt resist to say that. :wink:

Nice job,Nova. This should benefit the forum very much.

xwingband
10-09-2007, 01:00 PM
Heehee, he got burned, but I've been char-broiled. :wink: :lol:
Btw, just kidding x-wing. But I couldnt resist to say that. :wink:

Nice job,Nova. This should benefit the forum very much.

If I were an electrical engineer I wouldn't have to go to others for my electronic boards, I'd make them myself. :wink:

I still the gist is true. A n00b might read it a think why would I use a driver if I get the same thing from a resistor. Well, it's not completely... if that were true I'd never use a buckpuck!

Eandori
10-09-2007, 02:56 PM
Erv's board putting out 1 amp of solid current is 100% exactly the same as a resistor putting out 1 amp for LED brightness.
Yeah this statement is correct actually. You started talking about PWM, but that's not what I described above. I said 1 amp of solid current :) Still, It's best to have people keeping me in line though, I would hate to be misleading people on this stuff when it's already complex enough.

Current is current, no matter where it's come from. That's the essence of what I was trying to explain. What differentiates one luxeon "driver" from another is the special effects it applies to that current. How slow/fast/deep/shallow does the current pulse? A sharp spike in current, or a slow rolling hill? Those are the features we pay the big bucks for with special LED driver boards.

A driver board from the LED's perspective is like a variable battery. It literally "drives" the LED. A resistor is not really the same, it sits in series with that LED and statically burns off voltage in the form of heat and limits current flow through the LED. Both methods control current flow, but they really are pretty different. Having said that, if both methods are delivering 1 amp of non-varying current, then from the LED's perspective it's effectively exactly the same and will result in the same LED brightness.

Thanks!

Novastar
10-09-2007, 10:46 PM
The point of this thread is to help "dispel" erroneous thoughts about lumens, current, "3-watt" and all that, so I'm glad everyone is helping one another!

Eandori makes a REALLY good point as well that a resistor is essentially "killing" some power at one point by turning it into heat, while a driver (if made well) will do a lot less "burning" of power/current/batteries/whatever and manage that precious fuel to a much better degree.

Suffice it to say--a decent driver will almost ALWAYS yield longer run times vs. a resistor on an (otherwise) apples to apples comparison... aka same batts, same LED, same attempt to run at specific amperage, same heatsinking, same accessories run (motor, speaker, extra "little" LEDs), etc., blah blah blah.