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Colored Lights- How do colored led lights work and what do they emit? Answered

I'm doing an experiment by growing plants under colored led lights, so do led lights emit specifically one color. For example does a red led light emit only wavelengths of light that are red and no others. I want to make sure that only one color of light is existent to get accurate results. I hope this makes sense. Also if you know of any 1-colored high watt led lights please link them to me.

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bwrussell

3 years ago

Your best bet to accurately predict the wavelength range is use the broadest spectrum white light you can and then apply filters to only pass the desired wavelengths. This will eliminate variances between the individual leds. If they have to be naked LEDs then buy from a source that can provide a datasheet which should provide the necessary info.

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icengbwrussell

Answer 3 years ago

Even then they Lie and send outer ends of the bell-curve.

I design circuits for a marine environment.

30 LED COM.jpegphoto12.JPGphoto10.JPG
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bwrusselliceng

Answer 3 years ago

If it falls on the curve then it isn't really a lie.

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rickharris

3 years ago

The colour of LEDs is fairly narrow band. You should be able to see what the colour range is by looking at the data sheet for any LED.

There are Grow LED light which combine blue and red LEDs in the bands that best suit plants (they say.)

Be aware thet some/many cheaper Chinese grow LEDs may NOT be isolated from the mains and the front may well be at mains voltage, NASTY.

Also covers the colour values.

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Wired_Mistrickharris

Answer 3 years ago

Aww you beat me to it :P

If you buy your led's online, or nicely ask your local electronics store then will tell you the range of wavelength that the Led will Produce. Each wavelength in the Visible spectrum will appear as a different color in your eye.

For example in a RGB led, you have three different led's in one case. Each will emit it's own unique wavelength, and blend together to form the colors that we can normally see.

Even IR and UV lights have their own wavelengths we just can't see the light that they produce. You only see the effects they cause, like glowing objects or generating heat. You may want to include one of each to cover both extreme ends of the spectrum as well.

As per links, Ebay or Digikey/Mouser would be your best bet.

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iceng

3 years ago

Some spectral charts that may help you visualize that which is not readily apparent.

LEDs can easily be used to mimic all the lights needed for growth.

Be sure to click these pictures to see all of the info presented.

Wave-grow.jpgWave-white-LED-vs-RGB-LED-spectrum.jpgNone
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Jack A Lopez

3 years ago

It turns out the spectral emission of LEDs is typically very narrow. That is to say if you looked at a spectrograph, a graph of power versus wavelength, for a typical LED, then you would be looking at a graph with just one narrow peak.

For example, I would expect the spectrograph for a red LED to be just one peak, centered at somewhere in the red part of the spectrum, like maybe around 650 nm.

Similarly, I would expect the spectrograph for a blue LED to be just one peak, centered at somewhere in the red part of the spectrum, like maybe around 490 nm.

Spectral data for a specific LED, might be available in the manufacturer's data sheet.

As an example, look at page 6, of this data sheet,

http://www.ledsupply.com/content/pdf/leds-cree-xpe...

There are two graphs on this page. The one at the bottom is a spectrograph for seven different one-color LEDs. As you can see from the graphs, most of these are just a narrow peak, although two of them are much wider, for some reason, namely the plots for "Green" and "PC Amber" are wider than the others. In fact the plot for "PC Amber" is really wide. Why is this? I dunno.

If you want a more precise way to say what is wide, what is narrow, the usual trick is to draw a line at 50% of the peak, then measure the width at that line. Using that method, the width of most of those peaks is about 25nm, except for "Green" which is about 50 nm wide, and "PC Amber" which is about 100 nm wide.

The page where I found that data sheet is here,

http://www.ledsupply.com/leds/cree-xlamp-xp-e2-col...

So, they sell those. The reason I was looking at that particular style, the star-shaped package, is those are pretty easy to work with.

They give you some solder pads, so you can solder your wires to them, and for heat sinking you can just bolt them to an aluminum plate.