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erv
04-12-2007, 02:20 AM
Hi !
I've been asked to test various power supply sources for my sound board, crystal focus saber core (also known now as "buttered toast").
I tested several luxeon (III, K2 and V) to see which minimum voltage you should put in to get a the real desired current and therefore the corresponding lumens.
This comparison will probably help you guys findind out which lux version to use with your saber.

: I've updated the measurements to all luxeon I could test. And for the luxeon V, actually the results are better than what I initially test (due to a poor lab power supply which tended to make me think the lux V needed more voltage to operate).
You can find the full article here :
Luxeon Performance with Crystal Focus (http://www.plecterlabs.com/catalog/article_info.php?articles_id=25&language=en)


I've been asked to test various power supply sources for my sound board, crystal focus saber core (also known now as "buttered toast").
I tested several luxeon (III, K2 and V) to see which minimum voltage you should put in to get a the real desired current and therefore the corresponding lumens.
This comparison will probably help you guys findind out which lux version to use with your saber.

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►Luxeon III green (or white/cyan/blue). Supposed to run at 1 A.

3.6V : we are under the nominal 1A. The luxeon runs at about 800/900 mA. It's normal, those luxeon colors have a higher forward voltage of about 3.7V. Ramp effect acceptable.

5.2V : we get the 1A and the current regulation. Perfect retractation/ignition effect. And the same at 7.4V.

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►Luxeon III red (or red-orange/amber). Supposed to run at 1.3 A (max handled by the board).

3.6V : we obtain directly the nominal 1.3 A, thanks to the low forward voltage of the red luxeon. It therefore works as well at 5.2V and 7.4V. However, at 3.6V the ramp effect is not so smooth but still can be tuned with the slopefactor and brakepercent parameters on the SD card config file.

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►Luxeon K2 green. Supposed to run at 1.3 A (max handled by the board).
Parameter on the config file
ledcurrent=60
brakepercent=0.9
slopefactor=0.3

3.6V (li-ion single cell simulation) : actual voltage 4.2v (when fully charged).
nice ramp effect, pretty smooth. Not running at 1.3 Amp. RMS current measured : 0.91A (normal since we are under the nominal forward voltage of the luxeon).
With the K2 datasheet and a simple lumen to amp ratio, brightness is about 80 lumen in this situation.
In the same situation, the same ratio calculation with a star III spec (80 lumen at 1amp) gives 72.8 lumen.
Still brighter than a Lux III, but your eye won't make the difference IMO.

5.2V (4 AA rechargeable battery pack - fully charged).

7.4V (double cell Li-ion or 6 AA rechargeable nimh pack simulation). Test voltage : 7.4V - however, the double cell pack gives 8.4V when fully charged.
Perfect ramp. Full 1.3 amp running (checked with RMS current measurement).
Better sound than at 3.6V (the output amp is a bit under powered at 3.6V), little louder.
Takes the benefits of a K2 with theoritically 112 lumen for the brightest version of the K2 (U00 model).
Board is regulating the current during the whole life of the battery. If using a li-ion double cell with protection ICs, the battery will actually be cut off before the voltage is low enought to start the lowbatt indicator. A bargraph might be more usefull in this situation if it can fit in the hilt.


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► Luxeon V green. Supposed to run at 700 mA (max ratings)
Parameter on the config file
ledcurrent=32
brakepercent=0.9
slopefactor=0.3

requires around 6.7 V to start behaving properly. Hence, no test at 3.6V neither at 5.2V.

6.7V : luxeon RMS current measured at 700 mA. Luxeon RMS voltage = 6.2V
P = U x I = 6.2 x 0.700 = 4.34 watt.
Note that a fully charged batt pack (li-ion double cell) will start with a higher voltage, around 8.4V. At that voltage, you'll have the full benefits of using a lux V plus current regulation.



hope this helps ! Any question or comments are welcome
Erv'

Novastar
04-20-2007, 06:39 PM
Hi everyone... this is exactly what Erv figured out pre my request on thinking about trying differing setups with 3.6v and 7.2 li-ion...

Thanks Erv... this was GREAT info!

I'll be wiring a K2 with "buttered toast" at 7.2 (effective 8.4 at startup) and see how things go!

Almost there! Saber is prepped and ready to receive Erv's board....