LED and other Lighting
Self-made LED panel general discussion in the
Indoor Growing forums; Originally Posted by Gastanker
I swear those one of those pages is in mW flux -
Those are in lumen ...
Those are in lumen exept for the royal blue which is stated in milliwatts.
Originally Posted by Gastanker
Once we have the radiant flux in mW, it is easy to get the PAR as it is basically watts per lit square meter. And once we have the PAR it is easy to compare the micromoles of photons as it is the PAR proportional to the wavelength, as stated by jubiare. Even if it is not the only unit to take into account when designing a grow light, it is much much more satisfactory than only comparing lumens (which are only relevant when comparing lighting for human beings)
But once you have the PAR you still can't compare as plants don't use all PAR equally... Definately much more useful than lumen of course.
Last edited by Gastanker; 05-22-2012 at 08:01 PM.
I'm also realizing that the colors and whites all run at different voltages so even if they are testing under the same mA they are using different amount of energy to produce the varying lumen outputs which like you say have little to do with efficiency.
yep, reds are more likely to run around 2.2 volts whereas blues and whites have a forward voltage of about 3.2 volts; this means that blue and white LEDs chew up more electrical power than reds when at the same current. This is why it is good to keep in mind the radiant efficiency (milliwatts of light emmited for each watt of electricity consumed) rather than the radiant output alone.
Someday they'll make wider spectrum colored LEDs...
Have you looked at reef forums about any of this? Many many DIY LED aquarium lights out there and they tend to be a bit more of an academic group - never once seen a lux meter over there but somehow every other person owns a really nice PAR meter. Aside from them focusing on different spectrum they use all the same gear.
Patrik what kind of "white" LEDs are you talking about? RGB or phosphorous conversion? I'm also curious to know what you know about phosphorous blends and which ones you've heard of that have excellent peaks in the blue and red spectrums that growers like. Do you prefer blue or UV based white LEDs? And what is your opinion on this: Which is better a 2 pc or 3 pc white LED? I think the yellow spectrum in the 3pc is a waste, but maybe the plants can use it. (Gastanker?)
In other words, what I'm really trying to tell you is not to get too hung up on power. You need to do a little more probing to find the right white LED than just using radial-flux and par, though I totally agree that both are very important. Many pc LEDs have a ton of green in them making them not very efficient for growing weed, but somewhat efficient for lighting a room. As far as I know no one makes a white phosphur converted LED that hits peaks in all the spectrum's a grower would covet, though there are some newer phosphors that can get close.
IMHO a white 450m blue diode pc LED can replace blue LEDs without the photo-biological damage that blue LEDs can pose. For the 450 spectrum, most blue-diode based white LEDs will do since that's the spectrum many LED makers like to use, though not all do, so you need to see the spectral output of a white LED to be sure it's what you want to use. Then I would take what your trying to deduce and see how that LED stands up. Here's a spectral output of a 7000K white Epistar. OK for blue, but that's it really. Too much green for me:
Where's the reds?
I guess what I'm also trying to say to you is LEDs are not CFLs and they shouldn't be HIDs. Good luck Patrik and if I find any good white LEDs I'll let you know.
That's correct, milliwatts is the best we can use
Originally Posted by patrikantonius
Someone mentioned spectrum of white LEDs and again, I'm no expert, but the CREEs look sexy as fuck to me.
Regarding yellow light - yes plants can use it. To what degree varies among plants. I have no idea how much of it MJ can absorb in relation to other spectrum.