color change - a new problem?

[shark_attack]

Hi Stephen,

i ve got a problem. I think my DS-500 is a little bit darker (i ve got this feeling since few months) and sometimes the color change from red to red-orange (bright red). Can you help me? Today, i had the color problem again...:(

Best regards,

Björn

[Stephen]

Hey Björn,
This is a new one... at least I've never had anyone else mention something like this to me. Just from a general perspective, however, these LEDs should only normally go through a minor spectral shift (from a "darker red" at level 1 to a "lighter red" at level 5) as you increase the drive current up to the maximum. In all my experience with LEDs, the only time that I've ever noticed any significant color change, would be if the LEDs were somehow being over-driven. In other words, more current was being pushed through the diode than it was designed to handle. The MaxFlex is very capable of overdriving the LEDs, IF and only IF you were to have modified the maximum drive current level (MaxFlex menu item #2). They should only ever be driven at a maximum of 700mA.

If the max drive level was inadvertently set at 1000 mA, then the LEDs would continue to work at roughly the same brightness levels (might be just slightly brighter), but over time they would likely start to lose efficiency and/or start to exhibit a color (spectral) shift. Just for fun, you might go to the MaxFlex menu item #2 and set the drive level to 350mA, and notice if what you are seeing goes away. If it does, then change it back to 700mA and let me know what you find out?

Check your MaxFlex manual for the specifics on menu item #2, but here are the basics:

0 click (dim) -> 350 mA select
1 click (brighter) -> 500 mA select
2 click (brighter) -> 700 mA select (DesignShine Default, never to exceed)
3 click (brighter) -> 1000 mA select (Danger!)
4 click (brighter) -> 1200 mA select (Danger!)
5 click (brightest) -> 1300 mA select (Danger!)

Thanks,
Stephen

[shark_attack]

Hey,

i am so happy about your fast answer! I will test it. I only changed the strobe mode. I will get back to you.

Best regards,

Björn!;)

[shark_attack]

Update. I tested your settings. I think, its ok. Perhaps - It grows on you. After one year the ultimate brightness is just normal for my eyes?! Thx for your great help. So i know which setting works for the brightness level. I used mod 3 - 750 mA.

Greetings from Germany

[Stephen]

Hey Björn,
Good deal. Glad to hear that all is well.
Here's some more information that may be useful to you as well. As it turns out, RED LEDs are the most sensitive to decreases in Luminous Flux (as much as 40%!) as temperature increases. Human eyes generally can't see changes less than 15%, so it's possible with the RED that if you were to compare on a super cold winter day vs. a very hot summer day, you might actually be able to notice a difference. Also with increased heat, the red spectrum will shift to slightly higher wavelengths (toward orange). Also, there is the aging factor to consider. LEDs will actually lose maximum intensity as a function of age and/or use. However, I think this should be a pretty slow process for this application (we're talking about 10's of years here).

Concerning any additional hardware.... Currently I'm planning on finishing up the remainder of the housings in this batch (around 30), which are all pre-sold, then I'm going to take a break for a while and figure out what to do with the concept long term. So yes, in theory, I could build a unit with a different color LED, but I currently don't have any hardware available to do it. Also keep in mind that when you talk about total lumen values, they are always a function of the total color spectrum. When you have a very pure wavelength, such as RED, a lumen value of 500 would be very comparable to a full spectrum (white) lumen rating of 1200 - 1500. It's very hard to determine "perceived" brightness just by the lumen numbers alone.

Hope that helps a bit.
Thanks!

[shark_attack]

Hope that helps a bit.

haha... its a huge help!!! I am so happy about your comprehensive analysis!!!:rolleyes:

Great Work Stephen!