Gransee, other manufacturers, light experimenters

What would happen if a red, blue, and green led were fitted to a flashlight. I assume a white light would result but maybe a little flawed since they are not all equally bright. If we were to compare this to three white led's in the same design flashlight, shouldn't we get a brighter light with the same current draw???
If this is practical, it would be neat to have a light that could have any one of the led's on individually to conserve power and all on for a bright whitish light.

Good question Jon!

One drawback would be the beam quality. The three colors would need more lens treatment to form as tight of a beam as three whites.

Althought the numbers below indicate that the primary color setup could produce more candela, I think the gains would be negated by lens, circuit and white quality problems (each part runs at a different voltage).

Compare:

3 5,600mcd 20 degree Nichia whites= 16,800mcd

- or -

1 8,000mcd 10 degree Agilent red
1 3,000mcd 15 degree Nichia Blue
1 10,000mcd 15 degree Nichia green
3-21,000mcd total

Notice I used narrow beam primary colors and wider beam for the white. Using the same beam width on the primaries would also reduce their Cd rating.

One merit of the design would be you could use a fancy switch and dial in all sorts of hues from the light.

It would be tricky to get good quality white out if though. You would have to underdrive some of the primaries to get the color right. Just matching the primaries for a workable white might loose all your extra candela right there.

Not worth the trouble in my opinion.

Peter Gransee

Your probably right, might not be practical. It might be fun though. If each color was driven the same to keep it simple, I wonder what color we whould have. also might be interesting to see the color transition was we move away from center since the beam widths are not the same.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by JonSidneyB:
Your probably right, might not be practical. It might be fun though. If each color was driven the same to keep it simple, I wonder what color we whould have. also might be interesting to see the color transition was we move away from center since the beam widths are not the same.<HR></BLOCKQUOTE>

Jon, maybe not impractical. Have you read this topic?

Phantom Light topic - "Anybody have one of these?"

Looks like someone else had your same idea.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by JonSidneyB:
What would happen if a red, blue, and green led were fitted to a flashlight. I assume a white light would result but maybe a little flawed since they are not all equally bright. <HR></BLOCKQUOTE>

Chris Vernon made a light like this, using 16 LEDs. It had 2 red, 2 yellow, 6 blue and 6 green LEDs. One of his prototypes had only red, blue, green, but it turned out that the red LEDs became so efficient that the light was too reddish. More than 2 years ago he came close to 25lm/W.
His conclusion was that this is a nice thing for a homebrew product, but it will not be possible to make it comercially, because it needs some time for adjustment (which will make a comercial product expensive).
When shined on a white wall you can easily tell spots where one of the colours dominates, but when used it practical life, you cannot tell it. Actually it is a very useful light (and has other nice features built in).

Chris is a professional LED applications designer.

try a high brightness AMBER & CYAN together, they both are some of the higher brightness leds
and the combination is as white as a incadescent is yellow
just make sure they both have the same pattern of degrees, and it makes a good light, sure it is going to have places that are the seperate colors, but its like using the higher brightness leds and still being able to see all the colors for what they are.

biggest problem is the powering of them as they are both different voltage.

i think this is a great way to do a flashlight, mabey not such a good way to do a real light.

also theLEDlight.com now has 9$ (dang pricey) rgb leds for doing this, but all the same problems still exist except the Single LENS for all three