Calling out to Weezard for LED advice

This morning I was able to have another conversation with the manufacturer. This place holds the original patent to the UFO LED light.

I was explaining to him how others have seen the current draw around .31 rather than the .75 that it was supposed to be.

He said that other facilities in china are selling these lamps using .5W LED's and advertising them at 1W. To the eye they look the same, but when you put them under testing equiptment the results tell the real story.

He is currently working on 3W and 5W versions. So later this year I may have another light to fiddle with if I don't build a custom one. We'll see. These lights coming should be nice though! :jointsmile:

hello...
have been lurking about for a while now or as i like to call it...getting a free education.
if i start naming names...i will surely leave someone out so...
thanks to all, quite a read so far...

have decided to join your led party if i may, i love a project with a happy ending.

playing with ledeng 5 watt leds (from mouser so unknown bins).
660nm red, 465nm blue and warm white.
except for the soldering (really great heat sink, needs massive soldering iron)

trying to grow inside 5 gallon white buckets,
leds mounted on lid, 1 plant inside each white bucket.
leds glued to computer cpu fan/heatsinks. (cheap and very reliable)
1 bucket with 4-5W reds and 1-5W blue, 14.6 volts @ 1Amp.
1 bucket with 4-5W reds and 4-5W warm whites, 24.4 volts @ 1Amp.

last night, the red/warm white combo toasted a plant like in an oven...
didn't even have time to say goodbye....
it is time to pulse(pwm) them for brightness adjustments.

brain pick time..........

Q. am designing a fixed current source for pwm...
would i design the current max to be the 5W led pulsed max 2 amps?
( the pwm could then pulse about 2 amps for max uE....right?)

am not sure of what the voltage will do when the current is switched off by pwm.
cannot exceed led voltage specs by too much.

the voice of experience says.....
higher than max led voltage very very bad...will not love you long time.

i stole this pdf somewhere (if from one of you...oops...sorry) and as i read,
it mentions that plants can be pulsed. since it is so easy to pwm...i like their way,
but is it right? need some forum brain trust action.

"The light utilization efficiency and relative photon requirement of photosynthesis in pulsed and continuous light from light emitting diodes (LEDs) has been measured.
First, we characterized the photon requirement of photosynthesis from light of LEDs that differ in spectral quality.
A photon requirement of 10.3 f 0.4 was measured using light
from a 658 nm peak wavelength (22 nm half band width) LED over the range of 0-50 pmol photons m-2 s-'
in 2 kPa 0 2 in leaves of tomato (Lycopersicon esculentum Mill., cv. VF36).
Because the conversion of electrical power to photons increased with wavelength, LED lamps with peak photon output of 668 nm were most efficient for converting electricity to photo synthetically fixed carbon. The effect of pulsed irradiation on photosynthesis was then measured.
When all of the light to make the equivalent of 50 pmol photons mp2 s-' was provided during 1.5 ps pulses of 5000 pmol photons mP2 s-' followed by 148.5 ps dark periods, photosynthesis was the same as in continuous 50 pmol photons mP2 s-'.
When the pulse light and dark periods were lengthened to 200 ps and 19.8 ms, respectively, photosynthesis was reduced, although the averaged photon flux density was unchanged.
Under these conditions, the light pulses delivered 1017 photons mP2, which we calculate to be equivalent to the capacitance of PS I or PS 11.
Data support the theory that photons in pulses of 100 ps or shorter are absorbed and stored in the reaction centers to be used in electron transport during the dark period.
When lightldark pulses were lengthened to 2 ms light and 198 ms dark, net photosynthesis was reduced to half of that measured in continuous light.
Pigments of the xanthophyll cycle were not affected by any of these pulsed light treatments even though zeaxanthin formation occurred when leaves were forced to dissipate an equal amount of continuous light."
thanks to: Daniel J. Tennessen Raymond J. Bulba Thomas D. Sharkey 1994 u of wisconsin
link to whole pdf: https://mywebspace.wisc.edu/tsharkey...ght%201995.pdf
sorry kind of long....perhaps somebody can translate......

148.5uSec/1.5uSec = 99 that should save some energy...............
but will need 100 times the number of photons for that 1.5uSec.
would not be surprised if it evens out in the end.

Q. any ideas on what frequency i should run the pwm?
according to dan, ray and tom above, it appears to matter........
(150uSec = 6666Hz ??? not sure what 150ps is and what the heck is a pmol does p equal u ???)

Q. anyone have any way to convert from led output to uE's???

i have been mistreating electrons since vacuum tubes,
so if anyone needs any help in the designing
or the killing of electronic type thingys you but have to ask.

i do go on and on.....
but a toke or two helps the juices flow,
this is not so simple a subject!!!

thanks for all your help...
19toker45

Inside every older man is a younger man,
wondering what the hell happened!!!

Sounds like you'll feel right at home here.
Been hoping someone would volunteer to try pulsing.
Oh, psec is pico-second
Prolly pico-mole as well.

What's the verdict on the warm/white leds so far?

Aloha,
Weezard

Weez,

Here is a link to the pictures of the test results from the actual LED's that went into my lamps. The files are named according to wavelength.

Pictures by ledtime1 - Photobucket :thumbsup:

Hello 19toker45,

That scientific paper was originally posted by Physicsnole, and is one of my favorites. It was the first paper I'd seen where they used LEDs to try and see what wavelength of light worked for photosynethsis rather then use another light source and filters. Keep in mind that paper is at least 14 years old tho. I really wish someone would come up with some newer research papers for us to work from. And of course, the pulsing idea holds some potential, but how to realize it seems hard to figure.

I was told by an engineer, who helped me with my first DIY light power supply, to always use a dimmer in the AC side feeding the power supply. The output of the dimmer is a square wave and is more efficent at turning the diodes on/off then a regular sine wave.

If I was going to pursue pulsing diodes, that is where I'd start.
(I hope igrowwithmatches reads this also)

Welcome to the mind warp known as LEDs.

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i love a project with a happy ending

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Happy ending cost $50 extra. You #1 G.I.! :thumbsup:

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trying to grow inside 5 gallon white buckets,
last night, the red/warm white combo toasted a plant like in an oven...

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You need ventilation, which you don't mention. Got any?

White buckets may present problems for lotsa reasons, especially if you're gonna try to flower in them. (Nothing insurmountable, though.) How'd you decide on growing in them?

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....perhaps somebody can translate......"50 pmol photons mp2 s-' was provided during 1.5 ps pulses of 5000 pmol photons mP2 s-' followed by 148.5 ps dark periods"

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As Weezard pointed out, a ps is a pico-second. A trillionth of a second. Equipment that can pulse at that resolution isn't exactly available at Radio Shack....

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148.5uSec/1.5uSec = 99 that should save some energy...............
but will need 100 times the number of photons for that 1.5uSec.

150uSec = 6666Hz ???

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Okay, here's a "small" :D problem: you substitued microseconds (a millionth of a second) for picoseconds. Subsequent calculations will be off by a factor of one million. :( (I know: picky, picky....)

Google "pulse width modulation" for more detail. It works great for dimming.
You only need to "pulse" faster than about 250Hz so your eyes can't detect it. Typical rates in PWM dimming range from 1,000Hz to 200,000Hz (cycles per second, for the onlookers), which is many orders of magnitude slower that those trillionths of seconds Sharkey et al. were dealing with.

Two way different animals. Sorry, you're not going to get "pulsing," as the term is bandied about here, out of a PWM dimmer. Hope this saves you some aggravation. :thumbsup:

Weezard,

I have a pic here. I'm in the process of setting things up and figured you'd like to see....

http://i735.photobucket.com/albums/w...1/IMG00030.jpg

It's brighter than bright. When I turned on the flowering light, without looking at the bulbs, just the light in the room I saw green when the light turned off.

It filled an entire 10' x 12' room with all red! We'll see how it does. Wish I had a lux meter to let you know.

can't wait to hear/see the results ledtime!

looks good.


-shake

So I wanted to see how good this blue veg light works. My wife has been growing fresh herbs outside and her stevia plant was looking VERY sad.

So yesterday I took it and put it under the blue light and this thing perked right up in about 25 mins. The leaves weren't wilted and droopy anymore!

It must be doing something right. Can't wait to see what it does with other things!

are you gonna do a grow log ledtime?

i hope that you consider it!


-shake