Discussion in 'LED and other Lighting' started by JorgeGonzales, Apr 19, 2016.
I like to eat the soft yellow coating on the vero cobz,its yummy
hes not really saying that, rather that the relationship between lumens and PPF has been discussed for years here. along with mccree absorption, QER, YPF, emerson effect, and why sometimes higher CRI is a better spectrum for our application
lumens/watt is a very useful comparative tool when in the same spectrum and technology. but everyone understands that lumens are for humans, plants want PAR, and in the right wavelengths. and COBs are an excellent source of the photons we seek.
On an absolute level, if you need to get above 2.2 umol/J, discrete diodes may have an edge, but in the typical 1.7-2.1 umol/J application, cobs have proven to be viable, flexible, and economical, by many many grows here and on other sites. when people are outyielding HPS at 70% of the energy usage with $1/watt DIY builds and <$2/watt prebuilts its hard to poo-poo COBs for our application
Absolutely. It's the only way to narrow down the potential candidates. But that's because the datasheets are luminous. The hard part is stopping at that point. I have kicked myself in the as more than once making bad decisions based on a cursory look at a new LED. LEDs are my job. I am involved in Horticulture LEDs with a major University researching narrow band wavelengths. That's why I do not use CoBs and lack CoB expertise. Although in general I have been opposed to CoBs. It's the light bulb mentality that I have issues with. I do not think cramming LEDs into a small area is advantageous and the only reason CoBs exist is because the light bulb mindset and people have such a hard time getting getting beyond the Edison days when it comes to lighting. I also do not like Edison's AC voltage and am of the opinion AC has no place in LED lighting.
Also I would likely electrocute myself working with lethal voltages.
@DrMisunderstood Perhaps the Quantum Boards would be interesting to you. There's a dedicated thread for them.
I do not think there is any debate in whether a discrete LED is superior to a CoB in terms of flux per watt. But we know that is not the only factor otherwise all grow lights would be using the same 201 lm/Watt LED. For the cannabis hobbyist, CoBs make sense. They do not make sense for a commercial operation. IMHO.
I am biased of course and I am very thermal sensitive. With the steep thermal slope of AlGaInP LEDs it is imperative. I would guess most of the cheaper Red Blue grow fixtures lose more than 40% Red flux due to inadequate thermal management. Where GaInN LEDs and CoBs will lose 10% max.
I think we may have reached the point where an LED HPS replacement is is viable where the cost is near equivalent and the LED PPFD exceeds HPS. Using discrete narrow band LEDs.
Lethal voltages? Since when is 50 volts DC lethal? That's one of the greatest things about cobs, low voltage and wattage.
If leds are your business and you don't like cobs then you are about 18 months behind the curve.
Yes, I did see their post. I understand why you would say that and it's a good suggestion. I do like the efficiency of the Samsung 561C LEDs. I have 100 of the 2700K SPMWHT541ML5XAWMS5 on order to use in some experiments, but that was because my first choice in the 561 series was not in stock.
I am currently working on a different PCB approach where the PCB and heatsink costs are negligible and LED case temperature ranges from 20-40°C at 1000mA.
I am using 0.4" wide 0.020" thick PCB populated with 2mm square LEDs. The fixture frame is basically the heat sink and the PCB serves as a thermal path to the heatsink. The PCB is that wide to allow it to be attached to the heat sink which costs about $3.00 per foot. The uniformity, based on simulations, is excellent without the need for additional optics. The fixtures are powered by 48V which makes it simple for them to be solar powered (which I do). The 600-700 mW Flux (56% Radiant Efficiency) LEDs are under $1.00. I just bought 250 of the deep blue for $0.12 ea., but I think someone at Digikey put the decimal point in the wrong place.
I am seeing 100-300V supplies being used because the 35V CoBs are in series.
I am in the business of horticulture narrow band research. No CoBs allowed.
I do not understand where you got the impression that CoBs are superior to discrete 1-3W LEDs, but I can kick the shit out of any CoB with discrete narrow band LED design.
So, an led strip light? That's nothing new, but if you can do it efficiently in monos in certain spectrums I would be interested in it for supplemental lighting to go with my cobs. Say around 670 or hit a blue peak other than the 440 that cobs always hit.
I'll take your word on that.
Luxeon SunPlus Series.
If you don't even know how to power cobs then you need to check your bias. There are a ton of us here that wire in parallel right around 50 volts.
If you think discreet narrow band diodes beat cobs for real world performance then you need to spend more time reading because of right now that has absolutely been disproven right here in this subforum.
Not your typical LED strip.
The photo is the bottom side of the PCB where the light is coming through the thermal vias.
I do like the Sun Plus 20 royal blue and deep red (aka Luxeon Color C). I do not like the Sun Plus 35.
I would not use the purple as it is better to allow the user to set the red blue ratio to whatever they desire. Thus far the research is inconclusive on red:blue ratios.
Have you read the Japanese research that states plants like green when lights are intense?
Some here would also use the far red and Luxeon Z 420nm.
I can't get the attachment because I am data throttled for a day or two. But from what I can infer I am very excited. I would pay a ton of money for low power, efficient monos on strips. You could mount them to the frame of an existing fixture and wouldn't even need to buy a heatsink.
Not sure, most likely, there are many studies on GL. I noticed recently broadband fixture manufacturers are misinterpreting a recent report on GL.
Did you see where I mentioned I work for the Horticulture Dept of a major University doing research on narrow band LEDs? Every species we work with starts out under treatments of 100% Red, Blue, Amber, and Green. If I were a plant, I would not want to live under Green Light.
Here is how Green Light (GL) did with cucumber:
This I find to be a better study on the subject, It basically says the wavelength is not that important..but... (I'm not yet allowed to include a link)
Sensitivity of Seven Diverse Species to Blue and Green Light: Interactions with Photon Flux
Snowden MC, Cope KR, Bugbee B. PLoS One. 2016 Oct 5;11(10):e0163121. doi: 10.1371/journal.pone.0163121. eCollection 2016.
PMID:27706176 Free PMC Article
From the report:
Effect of green light
Chlorophyll concentration significantly decreased with increasing GL only in cucumber at the higher light level among the comparable treatments (Fig 17). At the lower light level, chlorophyll concentration significantly decreased with increasing GL in tomato, cucumber, pepper and lettuce among the comparable treatments. For all other species at the lower light level there was minimal change in chlorophyll concentration and GL increased. Chlorophyll concentration increased with PPF for all species, but the magnitude of the change was not consistent among species.
Yeah, that's all right!
But green light "can" be also very useful if you have allready enough blue and red light.
As example, bigger plants and trees use red and blue light most on its periphery but lots of green is used in the deeper, shaded plant sections.
Many plants have different requirements and for our it has been shown that green is very useful and delivers better results than red and blue alone. That's why we use white light in warm CCT areas sometimes with some additional blue, deepreds and far reds.
have you seen the new Chilled's PCB's?
They use 561c whites with additional sunplus mono's..
Really nice boards and up to 2,62-2,92μMol/j..
2 GPW from the better growers here who were never able to achieve that with narrow band lights. granted were seeing a jump in red efficiency but nobody round here is ditching their warm-white based spectra any time soon.
results are results.
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