Lens and Reflector Optics for COB

What Optics do you use in your DIY Lamp

  • No Optics

    Votes: 132 45.4%

  • Glass Lens

    Votes: 58 19.9%

  • Reflector

    Votes: 118 40.5%

  • Silicone Lens

    Votes: 23 7.9%

  • Other

    Votes: 6 2.1%
  • Total voters
    291
bastovan20 said:
But i think that you people just convinced me that running cobs bare isnt a big mistake..like i thought..and that is a huge deal for me :-)
Click to expand...
When using reflectors you need to hang the lights higher above the canopy for uniform light distribution. Roughly twice as high when you go from 115 to 90 degree beam angle. Malocan compared bare COBs at 30cm (12") vs reflectors at 60cm (24") by taking a matrix of parts readings over the whole grow surface. The uniformity was indeed similar, but the average light level with reflectors was 20% less than with bare COBs.
 
ttystikk said:
More chips make more light; heat sinks don't. Sound logic, there.
Click to expand...


With chips being ~$10 it makes sense to get more in lieu of the parts needed to run them harder.

The balance for efficiency also needs to take into account environmental impacts. For example, if you have a colder environment, it might make sense to run the chips a bit harder and use the waste heat to warm the area. Saves you having to get a space heater.

In warmer environments, you want less waste heat to manage and you can get that by underdriving chips. That frees up power to run more chips and reduces the requirement for expensive heatsinks. Much easier to manage that heat and you can often use common material to passively cool.

Keep in mind that the heat still needs to be managed somehow. Getting as efficient as possible with your light sources helps with that. If you can run 4 chips 35% more efficiently than 1 for the same power, both an increase in light output and a reduction of heat generation occurs. The increase in overall light output correlates directly to the reduction in heat on almost a 1:1 ratio so it is one of the better ways to improve efficiency.

Try and run all of the led emitters you have so long as they still work.
 
Well,one aggain..i have grow tent 120x120x200 cm..
Winters are cold,summers are hot :-D

was planning to use 4 led panels for that space
Running at 150-180w each.

Parts:
4 draivers HLG-185H-C1050A.
20 heat sinks 125x60x25 mm
20 fans 60mm for each cob,each heat sinks
20 cobs citizen 1212,clue 048

My budget is very limited,and i was planning to asamle 2 panels at first.

I already bought a half or the parts for first to panels.

Sorry for my bad english,i hope you understand me well :-)

What would you people recommande?

I like idea with less cooling,and more cobs..i hate idea of wiring all that fans and stuff..

i would like to avoid that if it is possible to get more cobs,better efficency and less heat.

And you people have a lot of knowage i see..
And experience and practic work(much more important) so i think that you can help me a lot.

Thank you,great forum :-)
 
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I reverse run my exhaust and run as intake over over the cobs to bring the heat from them to canopy in winter time.
I also have lights dimmed to keep heat where I want in summer, but turn them up in winter to keep warm since I can stay at a safe heat with more light.
 
forgive my outburst here, out of nowhere, but I wanted to return to this early post because the subject comes up over and over again, which is better - higher or low current and whether to use optics, and what gives better penetration. Robin answers that pretty definitively. To paraphrase Robin and to add my own BS: the direction of the light is important. It's not magical. Light travels in a straight line unless it's lensed or reflected. High PPF is possible from cobs running softly (current comparison is two cobs at 700mA vs one cob at 1400mA), but for canna it often becomes important to focus the light toward the canopy, instead of it radiating in shallow angles to the canopy, especially if you have more cobs running softly. Depending on what you are growing, and what canopy depth you have to manage, and what PPFD your plants need, you might be well off with unfocused emitters of various intensity and/or distance from the canopy, or perhaps lenses would be best for your scenario. It depends on what you are trying to achieve.

Currently, as of 10/2016, the citizen cluo-1212 cobs are cheap at about $12. Compared to the CXB3590, the 1212 at 700mA/25W is about the same 50% efficiency as one CXB3590 at 1400mA/50W. Two 1212 per square foot would roughly compare to one CXB per square foot, with more diffusion. Running 700mA with the right lense the cobs could be mounted close to the canopy without stressing the plants but have good directional penetration.

The Ledil Stella HB lenses, which give the most rich focus, are currently $22/ea which SOUNDS high. But, for comparison, one 1212 at $10 plus one $6.50 mechatronix heatsink plus one $22 lense, equals a total of $38, less than the cost of one bare CXB3590 cob. One CXB3590 at $45 plus one beefy $15 heatsink plus one $22 lense equals a total of $82.

Two 1212's so equipped at 25W would have about the same power and PPFD, and lower price, than one CXB3590 at 50W so equipped. And the 700mA cobs could be run closer to the canopy while still having good penetration.

In addition, the design of the Stella HB lense might perfectly complement the 36V/700mA power band, which 25W TDP would run cool and bright on the cheap 33W heatsinks https://led.cdiweb.com/ProductDetail/MODULEDMICRO8650B-MechaTronix/574036/

I'm guessing the thirty-two 1212's at 700mA covering a 4'x4' might be the DIY sweet spot for maximum point source distribution with good directional focus for penetrating the canopy at about 1000PPFD at about 12", and you get more color temps to fool with if you like to mix and match a 5700K in with your 3000K, etc. and the fixtures should run cool and last a long time.

That would seem to make this ~$1800 DIY fixture an interesting alternative to Fluence Bioengineering products, which is what I'd compare it to, rather than comparing to a Gavita. But the price for the DIY is approaching the Fluence product.

But at this point I'd recommend DIY'er wait for the Vero 7 series anyway, that claim up to 210 lm/W at 56W, flux that is effectively double HID, per watt. If the price comes in around $30 per Vero 29 gen 7 that will be awesome.

But for now the DE HPS offers the most economical entry price, although there are heat and power requirements that add cost pretty quickly. Still it's hard for some people to plan to recover their extra investment sometime next year, it's easier to pay a little more every month. That's why the poor stay poor. Anyway, Phillips better start improving their LEC and HPS bulbs by an order of magnitude, or LED will threaten that business soon enough. Phillips took the 1150W DE HPS bulb from 2000µmol to 2100µmol in how many years? Bridgelux offering 210 lm/W over the last generation's 150 lm/W is an increase of over 25%. Imagine what efficacy we will see from future individual diodes.

robincnn said:
Penetration seems to be one of the main advantages of the lens and reflectors. I agree at softer drive currents the COB output is not as intense and would benefit more from optics.
View attachment 3577654
The light from COB has a wide angle. Reflector or lens tightens the beam a little so you get more penetration.

I think that even if you run at 1.4mA, 2.1 or higher watts, you could still benefit from optics.
The reflector or lens may have its losses but may actually help efficiently deliver more photons towards the plants.


View attachment 3577663
Consider this chart from from page 1. Assuming you have 1.4amps cobs spaced apart. The red represents light towards 1 sqft. The blue and red together represent light going at 4sqft.
Any photos going out of 4sqft box are at going too much side ways and are not going to be efficiently delivered towards grow space. For these sideways photons
a) if reflective sides then reflective losses, some photos will be reflected away from plants.
b) If large area of plants then those side photons hit somewhere on top of canopy. So you have high numbers on top of canopy but not as much light penetration.

That 4sqft area would be an angle of 90 degrees. Round to 100 degrees. 50 each side. anything outside +/- 50 on each side highlighted in yellow

View attachment 3577655
For taller plants and during flowering.When those photons in yellow area focused a little, it should give better penetration and better overall light utilization.
Which is essentially what a good optics can do. For example the Angelina Reflector as below.
View attachment 3577674
Click to expand...

BTW I culled most of the highest efficacy Vero29 gen 7 models of interest to me, from the Bridgelux DS93 data sheet:
http://www.bridgelux.com/sites/default/files/resource_media/DS93 Vero 29 Array Data Sheet Rev A 20160622.pdf

BXRC-27E10K0-C-7X
----855mA
----66.2V
------------------------------56.6W
------------------------------10026 flux 25C
9541
---------------------------------------------177 lm/W 2700K 80CRI


BXRC-30E10K0-D-7X
181 lm/W
38.3W
1050mA
36.5V
6929 flux at 25C
6751 flux at 85C

BXRC-30E10K0-C-7X 3000K CRI 80
----855mA
----66.2V
---------------------------56.6W
---------------------------10444 flux at 25C
9938 flux at 85C
--------------------------------------------185 lm/W 3000K 80 CRI



BXRC-35E10K0-D-7X
181 lm/W
38.3W
1050mA
36.5V
6929 flux at 25C
6751 flux at 85C

BXRC-35E10K0-C-7X
----855mA
----66.2V
--------------------------56.6W
--------------------------10757 flux AT 25C
10236 flUX AT 85C
-------------------------------------------190 lm/W 3500K 80CRI



BXRC-40E10K0-D-7X
183 lm/W
38.3W
1050mA
36.5V
6996 flux at 25C
6817 flux at 85C

BXRC-40E10K0-C-74
----855mA
----66.2V
-------------------------56.6W
-------------------------10861 flux at 25C
10336 flux at 85C
------------------------------------------192 lm/W 4000K 80CRI


BXRC-50C10K1-D-74
80
200 lm/W
38.3W
1050mA
36.5V
7669 flux at 25C
7472 flux at 85C

BXRC-50E10K1-C-74
80
----855mA
----66.2V
--------------------------56.6W
--------------------------11191 flux at 25C
10650 flux at 85C
------------------------------------------198 lm/W 5000K 80CRI


BXRC-50C10K1-C-74
70
----855mA
----66.2V
--------------------------56.6W
--------------------------11906 flux at 25C
11329 flux at 85C
------------------------------------------210 lm/W 5000K 70CRI


BXRC-57E10K1-D-74
80
191 lm/W
38.3W
1050mA
36.5V
7332 flux at 25C
7144 flux at 85C

BXRC-57E10K1-C-74
----855mA
----66.2V
------------------------56.6W
------------------------11384 flux at 25C
10833 flux at 85C
-----------------------------------------201 lm/W 5700K 80CRI

BXRC-65C10K1-D-74
70
197 lm/W
38.3W
mA 1050
36.5V
7534 flux at 25C
7341 flux at 85C

BXRC-65E10K1-D-74
80
195 lm/W
38.3W
1050mA
36.5V
7467 flux at 25C
7275 flux at 85C

BXRC-65E10K1-C-74
80
----855mA
----66.2V
-----------------------56.6W
-----------------------11593 flux at 25C
11031 flux at 85C
----------------------------------------205 lm/W 6500K 80 CRI
 
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That's fucking awesome, some of the best ones are available in quantity, starting at $25 to $30

"It's Go Time"
 
It will be interesting to see how efficiently the 66V gen 7 cobs run at 700mA - 900mA

as an aside, off the thread topic some more ;./ does anyone know what drivers are ideal for the 66V gen 7 at low current?
 
PhotonFUD said:
With chips being ~$10 it makes sense to get more in lieu of the parts needed to run them harder.

The balance for efficiency also needs to take into account environmental impacts. For example, if you have a colder environment, it might make sense to run the chips a bit harder and use the waste heat to warm the area. Saves you having to get a space heater.

In warmer environments, you want less waste heat to manage and you can get that by underdriving chips. That frees up power to run more chips and reduces the requirement for expensive heatsinks. Much easier to manage that heat and you can often use common material to passively cool.

Keep in mind that the heat still needs to be managed somehow. Getting as efficient as possible with your light sources helps with that. If you can run 4 chips 35% more efficiently than 1 for the same power, both an increase in light output and a reduction of heat generation occurs. The increase in overall light output correlates directly to the reduction in heat on almost a 1:1 ratio so it is one of the better ways to improve efficiency.

Try and run all of the led emitters you have so long as they still work.
Click to expand...
btt
 
bassman999 said:
Looks good, which cob is that at Digikey?
Click to expand...
scroll through the model numbers on the datasheet starting on page 10 and you will see that all the "C" models can run at 66V and higher. These "C" models are the ones that have the most lm/W (on the datasheet).

example:
BXRC-30E10K0-D-7X is 36V
BXRC-30E10K0-C-7X is 66V

BXRC-30E10K0-C-7X 3000K CRI 80
----855mA
----66.2V
---------------------------56.6W
---------------------------10444 flux at 25C
9938 flux at 85C
--------------------------------------------185 lm/W 3000K 80 CRI
http://www.digikey.com/product-detail/en/bridgelux/BXRC-30E10K0-C-73/976-1398-ND/6152408

BXRC-40E10K0-C-74
----855mA
----66.2V
-------------------------56.6W
-------------------------10861 flux at 25C
10336 flux at 85C
------------------------------------------192 lm/W 4000K 80CRI
http://www.digikey.com/product-detail/en/bridgelux/BXRC-40E10K0-C-73/976-1425-ND/6152435

BXRC-50C10K1-C-74
70
----855mA
----66.2V
--------------------------56.6W
--------------------------11906 flux at 25C
11329 flux at 85C
------------------------------------------210 lm/W 5000K 70CRI
http://www.digikey.com/product-detail/en/bridgelux/BXRC-50C10K1-C-74/976-1479-ND/6152489
 
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