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David, here is a "practically-free" version:

http://publiclab.org/wiki/foldable-spec

Basically, you need to print out this pdf. It needs printer, paper, glue, and wasted DVD-R (and some camera). This foldable version is something I didn't know about. The earlier version (USB Desktop version) was using a webcam, which I don't have. But with this new one, it looks like that you can use any camera like this:
http://publiclab.org/notes/cfastie/12-3-2012/spectrometer-testing
When I have some time, I should try it with my camera.
 
I looked at the pdf:
http://old.publiclab.org/sites/default/files/8.5x11mini-spec3.8.pdf

I don't see what it does. How do you scan the frequencies? For example, if I have a tungsten-halogen lamp as the light source and I want to determine the relative strength (either power or photon count) of the light coming from this source at 2 different wavelength bands, say from 500-550 nm and 550-600 nm, how do I manipulate the spectrometer in order to make this determination?
 
David, my understanding is that you take the photo of the "rainbow" which DVD produces. Then you upload it to a web-based software called Spectral Workbench, which evaluates the brightness of each 'rainbow' bands to produce the frequency spectrum plot. I think you need to take a photo of CFL and the source you are interested. The peaks in CFL is used as the calibration point of the frequencies. But I don't know the details (the web site is rather difficult to navigate), for example, I would guess that the white balance of camera could screw up the relatively brightness of different color band. But if you are using the same setting of a same camera, you may be able to compare different light sources.
 
Philips Luxeon XF-3535L

This is a super easy version of DIY LED with high performance. Almost no tool required (wire insulation stripper does help). No need to solder nor drill, so much easier than the other DIY LED. Efficiency is pretty high (> 140 lumen/W).

Parts:


Step-by-step assembly
The LEDs come as a flexible strip. Mine is 525mm long.



The backside of LED strip has adhesive already, so you peel the backing and attach it to the aluminum C channel (I cut the C channel to 22" length with a hacksaw) like a sticker.



This is the close-up of the diodes:



Each end of the LED strip has a connector. One is for + and the other is - (labeled). This connector (AVX 9176-400) is pretty simple to use. If you use 24 AWG (gauge) wires (either solid or stranded wire), all you have to do is push the wire in. You don't have to strip the insulation neither.



After I pushed in the wire, I used Kapton tape to cover it. It's unlikely to short it, but I happen to have Kapton tape.



You connect the + connector of LED to + (red) wire of the driver, and - connector to - (usually white or black) wire of the driver. I used this cheap driver (LEF-30W). Note that the sticker is reversed. So the DC output is actually on the left side with red and white wires (even though the label says that the DC out is right side). These are connected to the LED connectors. The wires of the driver are short, so you need to add a couple feet of 24-gauge wires (with wire-nut or solder).



Then the other side of the driver has brown, blue, and green/yellow (yellow with green stripe) wires, which is AC input. You need to connect an AC plug. The round stick is the Ground (refer to the next photo for the AC outlet). Then there are two flat blades; the bigger one is Neutral and the smaller one is Hot (Live). So you want to connect:
Green/Tellow = ground (round stick)
Brown = Live/Hot (smaller flat blade)
Blue = Neutral (bigger flat blade)

NEMA_5-15_Outlet_120V-15A.jpg


That's all you have to do. Here is the assembled and finished LED. I use soldering, but you can use wire-nuts to connect wires.



A test run. It doesn't look bright in the photo, but it is pretty bright, so you might want to wear sunglasses.




The next photo is showing the beam angle. From 1' distance, it provides about 2' wide homogeneous light. The C-channel looks like a decent reflector. The Cheerio box is not an ordinary Cheerio box. It is modified, and it is actually a DIY spectrophotometer (based on the one we talked earlier in the thread).



The aluminum C-channel, which is acting as a heatsink, does become quite warm, but it is not hot. A better heatsink would improve the efficiency, but the cost will go up quite a bit (LED is more efficient, when it is kept cooler).

Measurement
Driver:
AC input: 22.7W
Vf: 21.38V
DC current: 906mA
Driver efficiency: 85.3% (a bit low-end)

Light measurement at 1' away from the LED in the middle:
PPFD: 110 micromoles/m^2/s
footcandles with LX1330B: 655fc
footcandles with Gossen Ultra Pro: 420fc (the response curve of this meter is quite different, but I'm including it for the comparison with the measurements of my older posts).

The LED is about 2' long. Here is the values of 1x 24W 2' T5HO (actually consumes about 18.15W per bulb in 4 bulb fixture).

AgroBrite 6400K 24W (brand new)
PPFD: 58 micromoles/m^2/s

AgroBrite 6400K 24W (2 years of use)
PPFD: 33 micromoles/m^2/s

Odyssea Plant 24W (new, purplish "plant" light)
PPFD: 81 micromoles/m^2/s

Odyssea Plant 24W (after 3-5 months)
PPFD: 63 micromoles/m^2/s

With 4x bulb fixture with 4 bulbs in it (bulbs are not brand-new), you get
PPFD: 160 micromoles/m^2/s

So 2x XF-3535L (45W) can outperforms (about >30% more light than) 4x 24W T5HO (consumes 72.6W). The cost of this DIY LED is similar or cheaper than 4x 2' T5HO.


Comments:
There are several versions of XF-3535L. I chose 4000K version. This can do 147 lumen/W if you are driving it at 800mA. I couldn't find a cheap 800mA driver, so I'm slightly driving it harder (900mA). This means the efficiency (i.e. the amount of energy converted to light instead of heat) is a bit lower than 147lumen/W. With any LEDs, if you drive harder, the efficiency goes down. Warmer ones like 3000K may have slightly better light suitable for plants because it has more red light. The lumen/W goes down if you use warmer light, but lumen isn't a good measure for plants. From several measurements I have done with LED (with PPFD of PAR, not irrelevant fc or lux), the output relevant for plants (PAR) doesn't go down with warmer light. So I think using 4000K or something lower than that is optimum. Also XF-3535L comes in several CRI. Stick with the lowest CRI for the given corrected color temp (80 CRI instead of 85 in case of 4000K). Higher CRI ones have lower output for plants. There is also 4' version (and 900mA driver works well), so this would be a good candidate to replace 54W T5HO.

Note that the performance of this LED is impressively high. But the price is relatively high compared to COB LEDs like Cree CXA3070 or Bridgelux Vero series (I recently assembled Vero 29, and I'm very impressed by it, I'll try to post more about it when I get some time). DIY COB-LED is pretty easy, but it is slightly more time-consuming than this strip light (e.g. drilling holes and tapping). Other high performing COB LEDs exist (e.g. Citizen, Samsung), but I can't get a few samples. I also heard that improved LEDs are coming out pretty soon. It is difficult to compare the performance between COB and the linear XF-3535L, but I'm guessing that they are pretty similar to each other. So if you are for ultimate cost-performance ratio, go with COB. So year of 2015 will be exciting for us artificial light growers!

Note that there are lots of other "strip-light"-style LEDs. Most others are not worth using for plants. The efficiency is really low (for most of them).
 
a great project with great instructions. Very Interesting. Thanks
arent you worried about an unearthed and home built 'appliance' in a 'wet' environment?

I'm not particularly concerned about it. Majority of florescent fixtures are not technically rated for wet conditions, neither. But we use them with common sense, I guess. :)

I think most LEDs are enclosed in silicone or something, and they have been tested in high humidity environment (I think 85%RH or so, and it is mentioned in the data sheet). But it isn't a good idea to submerge these under the water. ;) I occasionally splash water to COB LEDs, but they haven't caused any problems (well, it is difficult to short circuit without putting them under water).

Do you mean no case ground by "unearthed"? This particular IP67 driver doesn't have the ground connected to the case of the driver, and the ground wire is simply connected to a ring. I think if this driver is installed inside another metal case, the ground ring is supposed to be connected to the external case. Since I don't have any external metal case, I'm not using it. Do you think I should connect the ring to the body of the driver? It seems that there isn't any need for the case ground (to the driver's body) since the waterproof driver is filled with silicone or something.
 
Im not an electrician so cant answer the question regarding grounding (=earthed). If its properly grounded then an earth leakage device will protect you. I would suggest that if you make something using mains voltage then you should know the answer. Of course 12V and low amps via a transformer is a different story and much safer. Id just hate it if you electrocuted yourself or a short started a fire. Please be careful. Sorry if thats a bit 'mothering'.
 
What an interesting thread!

My basement culture needs lots of light. I use Osram T5HO 865 bulbs. They do a great job. I had to remove the reflectors because they were too bright.

My experience is that my Paphs seem to like the cool light better. I have one 840 bulb but flower stems grow away towards the 865 bulbs.

As I have to extend my basement culture I don't like to add more heat. That's why I would prefer to use LED stripes or LED tubes for more light.
 
That's an interesting observation, fibre. I looked up the spec of 865 (6500K) and 840 (4000K). In terms of lumen, 840 is putting out more. Tyrone probably knows which one has higher PAR (he has a nice spreadsheet of florescent bulbs). But PAR might not explain the direction of the stem growth (this is called phototropism, and it is auxin-mediated response). As described at the bottom of wikie page, some plants appear to use blue light for this reaction (e.g. arabidopsis where phototropin is used as the sensor). Maybe Paphs are one of them. But this doesn't necessarily mean that Paphs grow (photosynthesize) better with blue light, though.

I agree with the heat issue; I can stuff more light with LEDs into my grow tent without causing heat stress. Also, since electricity is more expensive in Europe, you'll get more benefit by moving to (high-quality) LED than us in the US. For me, the payback period (i.e. the initial cost is covered by the savings in electricity cost) is 1-2 years.
 
Unfortunately I can't find any high-quality LED here in Europe that are essentially more effective than my Osram T5 HO. And their heat is an additional bonus for my basement in winter.
 
Great data, thanks Naoki!

FYI, if the beam angle is 120 o (i.e. 60 from the vertical) then you want the sides of the rail bent a little to focus the light more. At 1 ft from the LED, the light would cover a diameter of more than 3.4 feet (tan 60 etc... you can do the math).

David, see http://www.apsa.co.za/xenforo/threads/light-spectrum-data-base.4454/ . There is a database of spectra of various lamps. Osram gave us data in mW/lumen/5nm which was very helpful. Essentially, if you have the spectrum you can exstrapolate the photon per bandwidth (or at least make a very good guess). The issue with cheap digital cameras though is that they don't capture blue/violet/purple well. If you email Greystoke he will share the most upto data dataset with you as well as explain how to do the exstrapolation based on a few known "standard" peaks (such as typical mercury green, blue and orange peaks). A nice page with LED/spectral data is http://www.apsa.co.za/xenforo/threads/wolfs-led-diy.11072/ which will give you lux/PPFD conversion.

As regards LED strips, the 5630 LED strips are very good. 4 parallel strips gave 145 PPFD (at 10 cm), see http://www.apsa.co.za/xenforo/threads/wolfs-led-diy.11072/ These are cheap and easy to install.

Naoki, blue light is also used to signal the opening of the stomata so there is more involved than phototropism.
 
Id just hate it if you electrocuted yourself or a short started a fire. Please be careful. Sorry if thats a bit 'mothering'.

Thank you for the concern! :) But DIY LED isn't that complicated, and putting pre-made parts together; this is slightly more complicated than playing with lego or assembling a computer from parts! Other hobbyists (e.g. aquarium people) seem to design and build the constant current drivers from scratch, which is over my head (for now).

Unfortunately I can't find any high-quality LED here in Europe that are essentially more effective than my Osram T5 HO. And their heat is an additional bonus for my basement in winter.

I've heard that LEDs could be a bit more expensive outside of the US (even in Canada). But I think you can order via AliExpress to get the same cheap price as in the US. I can recommend Amelia Liu (Shenzhen OT-LED Technology Co.,Ltd) for Cree:

http://www.aliexpress.com/store/815938

She is easy to communicate with, and I managed to get the highest efficiency (top-bin, which is difficult to get) CXA3070 for cheap (same price as the lower bin). Here is the link to CXA3070:

http://www.aliexpress.com/store/pro...m-White-3000K-LED-Chip/815938_2052849889.html

You need to ask for the top bin via email, I got 5000K BB-bin since they didn't have AB-bin 3000K at that time. Everyone growing plants is looking for 3000K AB-bin CXA3070. Lower bins can be easily found from digi-key etc, but to get higher bin, you usually needs to order 20 or more pieces (i.e. you usually can't get 1-4 pieces from the usual domestic source). You'll get killer LEDs (no, it won't kill you as long as you use common sense) with these! 2x CXA3070 (at about 50W each) would be a good replacement for 4x T5HO (4', 54W) to cover 4'x2' area.

In Alibaba and eBay, you need to be careful because there could be sellers which sell fake. But this company seems to be honest.

If assembling isn't something you want to do, this European based Hans Panels seem to use good design and parts to achieve high efficiency. I calculated the cost of making a panel with similar parts, and it turned out that you don't save much. There are 65, 80, and 150W version. I was going to order these, but I figured out how easy it is to do DIY if I use COB-type LEDs.

FYI, if the beam angle is 120 o (i.e. 60 from the vertical) then you want the sides of the rail bent a little to focus the light more. At 1 ft from the LED, the light would cover a diameter of more than 3.4 feet (tan 60 etc... you can do the math).

I think the C-channel is acting as about 90 degree reflector. I agree that it is not the best profile for the reflector at all. So you are saying to open the channel: i.e. instead of |_|, it should be\_/, right?

A nice page with LED/spectral data is http://www.apsa.co.za/xenforo/threads/wolfs-led-diy.11072/ which will give you lux/PPFD conversion.

Thanks for the interesting links, Tyrone. But I believe that this link is not what you meant. If you can correct the link, I appreciate it!

As regards LED strips, the 5630 LED strips are very good. 4 parallel strips gave 145 PPFD (at 10 cm), see http://www.apsa.co.za/xenforo/threads/wolfs-led-diy.11072/ These are cheap and easy to install.

Naoki, blue light is also used to signal the opening of the stomata so there is more involved than phototropism.

The link seems to use SMD5050 not 5630 (which is a bit more efficient). I haven't kept up with the LED strip light technology, but according to this page (message #14), none of them have decent lumen/W.

http://www.candlepowerforums.com/vb/showthread.php?365587-Recent-LED-Strip-Comparisons

Are there better strip LED products now? The one linked in APSA thread seems to give only 62.5 lumen/W, which is even lower than household LED light bulbs. Philips XF-3535L is at least twice as efficient (147 lumen/W). This is why I mentioned that this is not same as the older generation strip light. Well, this is just based on lumen comparison (and not using PAR), but I think that there will be a similarly big difference in the PAR comparison. Indeed, I think XF-3535L may pretty good for planted tank, and I may use it for this purpose. A bit pricey, but you'll save money in a long run over SMD5050.

Yes, cryptochrome is the sensor for blue light, and is involved in several processes in plants.
 
The correct link: http://www.1023world.net/diy/spectra/

Silly me, I got ahead of myself. Wolf switched from 5050 to 5630 later on: http://www.apsa.co.za/xenforo/threads/wolfs-led-diy.11072/page-5 (but never gave me a Lux measurement). The 5630s are 3x brighter than the 5050s. So that should be 435 PPFD at 10 cm which would be about* 80 PPFD at 1 foot.

*This is a rudimentary estimate. I gave up working out the geometry of LED strip lights when I started exploring the geometry and calculus of overlapping circles. I must return to this problem at some point... There is at least 20% error in this guess as my simple model treated the point sources as squares, not round points.
 
Thanks for the link, Naoki. Have you tried the lower power CXA LED's? I'm getting far better flowering on my latest living wall, which is lit by a combination of 6000K and 3000K 5W LED's, as compared to my earlier living wall, lit by Ray's 13W combination LED light bulbs (which are overwhelmingly cool white).

I'm getting great green and root growth on both walls, but only the latest one has plants in bloom. So I'm thinking that a blend of colour temperatures is the way to go, and 50W is a little harsh for a single point source of light.
 
The correct link: http://www.1023world.net/diy/spectra/

Silly me, I got ahead of myself. Wolf switched from 5050 to 5630 later on: http://www.apsa.co.za/xenforo/threads/wolfs-led-diy.11072/page-5 (but never gave me a Lux measurement). The 5630s are 3x brighter than the 5050s. So that should be 435 PPFD at 10 cm which would be about* 80 PPFD at 1 foot.

Thanks, Tyrone. The spectra link is interesting, I should play with it. So it looks like Wolf's light is this one which uses Samsung chips. The web page doesn't have much info about energy consumption and other details (I'm more interested in the efficiency than the total output because you can increase the total output by increasing the number of electricity you use). But if it is using this LM561A, it can have fairly good efficiency. While I was looking for info quickly about 5630, I learned there are more efficient 5630. For example, Lite-on LTW-5630AZL looks pretty interesting (I didn't look at the data sheet in detail, but similar efficiency as XF-3535L). Also Seoul Semiconductor seems to have something similar. I should look into these in more detail.

Thanks for the link, Naoki. Have you tried the lower power CXA LED's? I'm getting far better flowering on my latest living wall, which is lit by a combination of 6000K and 3000K 5W LED's, as compared to my earlier living wall, lit by Ray's 13W combination LED light bulbs (which are overwhelmingly cool white).

I'm getting great green and root growth on both walls, but only the latest one has plants in bloom. So I'm thinking that a blend of colour temperatures is the way to go, and 50W is a little harsh for a single point source of light.

Alla, it sounds like your DIY LEDs are working well! Did you update your living wall thread?

No, I have used only CXA3070. Using many smaller ones would give more uniform coverage. Also in your case, where you want to have a narrow beam pattern (to get distance between plants and light), you can find better/cheaper lens/optics for the smaller LED or COB. But I use the bigger COB for the ease of making them. Note that CXA3070 can be driven really soft at a low current, and it will give amazing efficiency. But the initial cost becomes too high, and it takes long time to get the high initial cost covered by the efficiency advantage (and by that time, this will be an obsolete technology). If you are interested in lower power COB, I've heard that Vero 10 have pretty good performance/cost (and you have the skill to make these LED panels with many diodes). I think it is around $4.60, and cheap efficient drivers are available.

Recently announced Cree XHP might be interesting to you. XM-L2 like performance with much cheaper price.

Could the difference in your DIY and Ray's be from the difference in the beam pattern (and difference in the intensity at the plant leaves)? I personally can't tell 5000K or 3000K is better with orchids. They seem to grow and flower well in either. In theory (and from my limited measurement of PAR), warmer ones (like 3000K) seem to be better for photosynthesis. In theory, 5000K, which uses less phosphor, should be giving more total light output, but my PAR measurement says 5000K and 3000K doesn't differ too much. In this case, red-enriched 3000K should have more useful light for photosynthesis. But it is possible that my old Li-Cor PAR sensor became off (it is known that the blue sensitivity of this sensor decreases with age).

In some cases, different color temp LEDs use different blue emitters. Then combining them could increase the width of emitted spectra. But frequently, the difference is just the thickness of phosphor with the same blue emitter. In this case, I'm not sure if there is a theoretical advantage to mix different color temp. For example, if 4000K has the best spectrum for plants, you may get the same results by achieving the spectrum by mixing 3000K and 6000K.

Fibre, I'm not familiar with that one, but it seems like a nice one (although it seems very pricey for the performance). You should give it a try! My drivers are outside of grow area to reduce the heat in the grow tent. I have a short AC to driver cable, and long DC cable from the driver to the LEDs. So they don't get to take shower even though they are waterproof (or outdoor) drivers.
 
One thing that concerns me about PAR sensors is that it says nothing about wavelengths. An equal number of 450nm or 650nm photons per area per time is the same PAR, but obviously will give entirely different growth.


Ray Barkalow (via Tapatalk)
 
Just did a search on 'cree xhp led' on aliexpress.com - and got a 'no items found'. Must be a first! I guess the factories are getting ready for the new generation of chips (and Bridgelux can't be far behind) so we're seeing old technology led's being sold off at fire sale prices.

I haven't updated my living wall thread - I will do it early in the new year. Right now I have 3 plants still in bud, I'll wait until the flowers open.
 
One thing that concerns me about PAR sensors is that it says nothing about wavelengths. An equal number of 450nm or 650nm photons per area per time is the same PAR, but obviously will give entirely different growth.

Yeah, have a look at http://www.advancedaquarist.com/2013/2/equipment . My issue is that all seem to waver a little in the violet/UV range and then all drop off suddenly in the far red even though photosynthetic response does not seem to do this for terrestrial plants (the sudden drop in action spectrum is a limit of detection, not a real photosynthetic limit). The apogee might be the worst as photosynthesis peaks at about 680--690 and the apogee doesn't detect this at all!

I'm not sold on PAR being the end all of lamp selection. I think the spectrum is more important. The main virtue of LEDs is that their spectrum mirror photosynthetic response very well compared to flourescents.

Bye
 

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