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Old 07-28-2014, 08:34 AM   #1
tanan
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Cheap 3W LEDs.


Hey
I am getting thesehttp://www.aliexpress.com/item/50pcs...612906314.html cheap as hell knock off leds (50 pcs for 10$).
I am gonna use them to light up a 30" long. I have this led driver for 14-18 3W leds rated at 650mA.
Should I go with all cool white? I'm thinking of 6 Cool White, 8 Warm White and 4 blue leds. I will use 120 degree lenses and it will be around 6'' from the water surface and around 26" from substrate level. What do you guys say?

Last edited by tanan; 07-28-2014 at 08:35 AM.. Reason: forgot to add url
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Old 07-28-2014, 09:34 AM   #2
gus6464
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Cool white has enough blue spectrum you don't need more. If they are 50 for $10 why are you only using 18 LEDs?

Do cool white, warm white, red, and purple.
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Old 07-28-2014, 01:32 PM   #3
jeffkrol
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Quote:
Originally Posted by tanan View Post
Hey
I am getting thesehttp://www.aliexpress.com/item/50pcs...612906314.html cheap as hell knock off leds (50 pcs for 10$).
I am gonna use them to light up a 30" long. I have this led driver for 14-18 3W leds rated at 650mA.
Should I go with all cool white? I'm thinking of 6 Cool White, 8 Warm White and 4 blue leds. I will use 120 degree lenses and it will be around 6'' from the water surface and around 26" from substrate level. What do you guys say?
Like gus said.. and within a restriction I agree.. unless you are going to put "types" on separate channels the blue is unnecessary..

you need (and this depends on what you like) a 2:1 ratio of cool white to warm white for the beat visual effect.
1:1 visual ww/cw Cheap Chinese LEDs (color temps are not consistent batch to batch ect)


Adding "cw" or neutral LEDs in a higher ratio "cools" the tone from this..
All 6500k has a slight blue cast but rich white "look"..
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Old 07-28-2014, 06:51 PM   #4
tanan
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Because the spare driver I have supports 18 leds. If it works I might get another 2-3 drivers. I have a 10 cree XPE cool white with 4 x 3W 620nm leds and another with 9 coolwhite XPEs, 4 red 3w cheap chinese 620nm and 1 cree blue XPE. The one with the blue looks better to me.
Can I wire the red leds in series with cool whites/warm whites? Or I will need another driver? I use another driver for my current leds and I hate the mess it made for wiring.
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Old 07-28-2014, 07:28 PM   #5
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Quote:
Originally Posted by tanan View Post
Because the spare driver I have supports 18 leds. If it works I might get another 2-3 drivers. I have a 10 cree XPE cool white with 4 x 3W 620nm leds and another with 9 coolwhite XPEs, 4 red 3w cheap chinese 620nm and 1 cree blue XPE. The one with the blue looks better to me.
Can I wire the red leds in series with cool whites/warm whites? Or I will need another driver? I use another driver for my current leds and I hate the mess it made for wiring.
as long as you use costant current and the Led's can handle the mA ... no problem running different colors in series..

Why 620 nm reds.. not 660??
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Old 07-29-2014, 01:30 AM   #6
tanan
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Couldn't find any cheap 660nm. Is it worth it to get 660nm?
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Old 07-29-2014, 05:02 AM   #7
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Originally Posted by tanan View Post
Couldn't find any cheap 660nm. Is it worth it to get 660nm?
Arguable..660nm hit s the peak ch.A band..
And it is a ""low level" component in white LED's . Warm white has a fair amount of 620-ish red.

I don't like to leave things out.. except purple (don't ask.. )

http://hyperphysics.phy-astr.gsu.edu...gy/ligabs.html
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Old 07-29-2014, 08:33 AM   #8
tanan
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I don't know why I assumed warm white leds would be high on all red spectra.
I guess I will go with 8 white and 10 warm white leds. Would it be too yellow to look at? I like the tinge of slight pink but not yellow.
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Old 07-29-2014, 11:48 AM   #9
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Quote:
Originally Posted by tanan View Post
I don't know why I assumed warm white leds would be high on all red spectra.
I guess I will go with 8 white and 10 warm white leds. Would it be too yellow to look at? I like the tinge of slight pink but not yellow.
General CREE spectrum of LED "groups" Red line WW ect.



Warm whites are high in 620-ish red... most are similar..
cool whites have little 660nm red relatively speaking..

Using say 8000k and 4500k and red... You have a bit more control of the tone
Warm whites aren't horrible but I like the 660nm seperate kick for color..
Using 660nm red and 6500k whites seems to blend to white a bit better than warm white/cool white..

If you don't like yellow you should decrease WW (increase 6500k and above) but add a few red to make up for the losses.

An example using BML caculator:


A more "neutral" light:
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