DiY LEDs - How to Power Them

DiyKindaGuy

Active Member
Lumens and lux are photmetric units...
Photometry- is the science of the measurement of light, in terms of its PERCEIVED brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy (including light) in terms of absolute power. In modern photometry, the radiant power at each wavelength is weighted by a luminosity function that models human brightness sensitivity. Typically, this weighting function is the photopic sensitivity function, although the scotopic function or other functions may also be applied in the same way.

mW are radiometric units...
Radiometry- is a set of techniques for measuring electromagnetic radiation, including visible light. Radiometric techniques characterize the distribution of the radiation's power in space, as opposed to photometric techniques, which characterize the light's interaction with the human eye.
In photometric quantities every wavelength is weighted according to how sensitive the human eye is to it, while radiometric quantities use unweighted absolute power.

PAR µmols are...
Quantum- Which is basically identical to radiometric but a step closer to plants...it measures only 400-700nm(only Photosythetically active radiation) as compared to 380-850nm(all visible) that radiometry measures.

PAR in µmols actually is just fine in accuracy...or mW...both are equal really.
What I assume you mean by PAR isn't the best...is that a handheld "par meter" isn't the best. And that is because of the calculations to convert it to µmols it does internally and has a slight error based on nm's of the light. A spectradiometer will give an accurate µmol count that is just as accurate as the mW it also give.
If a par meter gave a mW read out, it would be off too. It's not PAR µmols that is not perfect...it's the device that takes the measurement.

And with all that said...a handheld par meter...even with the error...is 10000X better and more relevant than lumens.

What do you think is the best to use?

EDIT: You can send in a spectral chart of a light to apogee and they can calibrate the meter to the spectrum so it's accurate.

I got my meter from ebay.. really just wanted something to measure intensity of my diy led light panel... to compare it to the cfl lights and measure intensity between 1 watt.. 10w and 100w multichip i have not been able to get the reading from hps or commercial grow lights.. just my house cfl and diy led.. thanks for the post

★★★kushed_out★★★
 

Greengenes707

Well-Known Member
Do you have a source for that info greengenes? I'd be interested in doing some further reading.
They are just the definitions of those terms. I used basic definitions, but here is a good source for a little more. I would like to buy the thing to read it all... books.google.
In that link there is more on the details of the differences...page 14 has a nice little table.
Search around and study the 3 terms from where ever you can.
Radiometric and quantum are harder to differentiate...but that is because they are so similar when you already know a little about both. Both can be used for plant purposes, but quantum is ideal.
When you understand what each metric is exactly, it's easily see how photo metrics are just not good for our purposes...and where "Lumens are for humans" comes from...because they literally are.
 

SupraSPL

Well-Known Member
Good info GG,that is cool that apogee can custom tune.

I would add that lumens are only useful when you are comparing light of the exact same spectrum. Even more useful if you know the power consumption and LER of that spectrum because it allows you to convert from lumens to mW. Since lumens are referring to about the same range as PAR (400nm-700nm), when you convert from lumens to mW you are getting PAR Watts.

Once you have PAR Watts you can make much more effective cost comparisons (PAR Watts/$) Wouldn't it be nice if they all just gave us a trustworthy spectral graph and PAR Watts, ppf and ppfd in the first place :)
 

TheSnake

Well-Known Member
Holy fuck i need to read more about LED's and soldering. All i have is very limited electrical experience, basically enough to run another breaker for the grow, to be safe. This is like reading Chinese right now, granite, i have been drinking roughly tonight.
 

Mohican

Well-Known Member
My Father worked at ARROW back in the 80s. I wonder if he can get me a line on these for a dealer price?
 

guod

Well-Known Member
funny price...
1 - 9 pcs. 17.1293 USD
&so cheap 4 an outdated Led (voltage drop and Rth is to high nowadays)
LZ1.png
here we have the minimum Die temps dictate by the led itself,
these Values are only reachable with chilled cooling!


1.5 A... not for the long run
1.0 A... my maximum for this led
for both...2 Oslons cheaper & better




 

medicinehuman

Well-Known Member
Question about how to hook up 4 12v fans to my ATTEMT TO DIY cree light. What splitters ect. might I need. I have a $6 Ebay power supply coming. Thank you for any thing. I will start a short thread soon.
 

Chronikool

Well-Known Member
funny price...
1 - 9 pcs. 17.1293 USD
&so cheap 4 an outdated Led (voltage drop and Rth is to high nowadays)
View attachment 3142223
here we have the minimum Die temps dictate by the led itself,
these Values are only reachable with chilled cooling!


1.5 A... not for the long run
1.0 A... my maximum for this led
for both...2 Oslons cheaper & better
Thanks Guod. Yeah i can get them for $5.95 each..that was just a link that came up. Steves LED's also has the luxeons for $3.40 each.

It was just tying in with my 'current' design (<<<<<nailed it)

Havent really got a good link for 660nm Oslons on stars...
 
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