New to LED looking for assistance designing a light

DISTRESS0R said:

Im looking to do the same setup for a 1.2m tall 2x3 space. Id imagine that 6 cobs spread out running at 1.05a would get a good PPFD in either space, maybe Rahz can chime in

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6 at 1.5 amps will be fantastic in a 2x3 approaching 1000 PPFD. 1 Cob per foot (or more) is how people should be thinking about DIY IMO.

selfmedicator462 said:

I think I found all the parts I need. Just researching dimming circuits now and trying to decide on a configuration. Would it be beneficial to include 2 5000k imiters on a separate driver to use during flower? Or can I get good results with just 3500k? I'm planning on running 6 3590s (3 on each heatsink) with 2 drivers (dimming), 2 fans and will use my existing 240v line.

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Did anybody have some thoughts on adding 5000k?

Bonjour
Of course it will be great to have 2 x 5000/6500ºk for vegg...but imo it is not an obligation!
It will be great to save vegg time if you have a little vegg box (1x1x4.5) but if you don't 3500ºk will vegg very well!
I am not sure if an hlg-240-1050b do exist...but I think it is and it will run 6 cxb3590!...
As for 2 5000ºk I guess lpc-60-700...I am not sure about this one...if someone could chime in!
CU

I was/am impressed by the good vegg I had with my 3500ºk...so since 5000/6500ºk have a lot more blue it must be a great vegg light!
But as I said you don't really need it and not that big...cxa 2530 @700mA would be perfect for a short vegg it is cheaper and very efficient!
CU

selfmedicator462 said:

Did anybody have some thoughts on adding 5000k?

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5000K would be blue heavy for a flower chamber. Even 4000K isn't the most ideal when using Cree cobs. Most of the CXB manufacturers are using 3500K because it has enough blue light and the rest in orange/red.

yeah i meant veg. sorry. Mind thinks one thing fingers type the opposite.

Bonjour
So as I said if you only have one grow space...3500ºk all along!
If you have a vegg room it will depend on the size...
CU

littlejacob said:

Bonjour
So as I said if you only have one grow space...3500ºk all along!
If you have a vegg room it will depend on the size...
CU

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Just one grow room. I have a clone cabinet that i usually keep a mom in after i get one into flower. I might build a little LED for that cabinet as well.

The main good reason for doing it would be going with 4000K DB bin emitters. Luminosity doesn't increase from 4000K to 5000K, but 5000K might have slightly better electrical efficiency. Whether the extra blue from 5000K in veg would be a good thing I'm not sure. There's even a DD bin in the bin list but none of the emitters have it listed as an option.

Honestly I don't think there would be much difference in practice and 3500 is a good all around solution.

Rahz said:

3500 is the best K temp IMO. as far as thermal protection, design the light to run without fans. 5 in an X shape is pretty sweet, but you could do 2 bar lamps, each with 3 emitters at 1.4 amps and get some high intensity going in there. Run each 3 emitters on a HLG-120H-C1400B and hook the dim wires to a switch or potentiometer.

That way you could build two lamps, each on a 30" piece of the 4.886" profile from heatsinkusa.com. Put a fan on each and if the fan were to fail the lamp would continue to run no problems.

You could also consider 8 CXBs at 1.05 amps, 4 each on a 120H-C1400B. I'm trying to talk you into lower currents because A- you're height limited and B- it's DIY, saving some money so why not go the extra mile with a few bucks more and build something special? Lowering the current costs more up front but it will all come back to you over time anyway. Even using more emitters at .7 amps you come out good over the long run. Worth giving some thought if you have the cash to play with.

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im actually considering doing just that. Not sure if i should go 8 or go to 9 with 3 on each of 3 heat sinks. That way I have 1 cob on each foot of space. but then id have an odd number and need to choose a different driver set up. Ugh! choices.

Was just looking back over what I wrote, would be HLG-120H-C1050B running 4 CXBs @ 1.05... of course. Sorry about that.

Rahz said:

6 at 1.5 amps will be fantastic in a 2x3 approaching 1000 PPFD. 1 Cob per foot (or more) is how people should be thinking about DIY IMO.

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Thanks Rahz!
Just to clarify, did you mean 1.05amps?
What is the sweet spot for best outcome in PPFD?

Yea, 1.05... oops again. Never trust what I say!

If you look at the PPFD -vs- phototropic efficiency chart, anything above 700 starts to look similar but the response change is still a curve the whole way. I tried to pull the curve out of a single 3 point reading but it could still be worthwhile to consider the original data.



I used the 30C data for the graph, which seems like the best metric to me. I have also averaged the top three readings and the shape is much more of a hump, less gains as a percentage from the 1000-1500 mark. But perfect temps is the best way to take advantage of the ideal PPFD whatever a person deems that to be. If the goal is to grow as much as possible in a 2x4 the best PPFD would be higher than a goal of using the least electricity without seeing GPW suffer much. GPW might drop off from a peak on the low end, but this cannot be determined by the graph. What is the perfect PPFD as far as electrical efficiency? It depends on whether yield per energy unit increases at ever lower intensities.

If you put a CXB3590 at 1.75 amps over a 4x4 you have a PPFD of about 110. Would that grow 1.5-1.6 gpw (similar to higher intensities with same electrical efficiency), or 1.7-2 GPW or more? I don't know. Somebody should test that

I'm working on figuring that out using less extreme methods but it's still a work in progress.

Some have said the sweet spot is between 800-900 but there has to be an inherent practical/subjective reason for it, space concerns and wanting a "bountiful" harvest mostly. I've played around with 730 and 770, but at different efficiencies. At 730 PPFD I have achieved 3.43 gppw (grams per par watt). At 770 PPFD I have achieved 3.21 gppw. This data indicates the best GPW will be at or below 730. More data would be useful to see if it was a solid trend and whether the trend began to break down at some lower PPFD.

Bonjour
3.4 gpw!!! Wtf!...in hydro?
I never heard of such results!
Can you develop please...how many vegg, nutes, strains, etc...!
Thanks
CU

Not GPW, GPPW (grams per par watt).

(yield in grams) / (emitter wattage x efficiency)

Gppw would be more an indicator of PPFD efficiency (and grower skill) rather than electrical efficiency. Sometime late Spring I will have a better idea of how 500 PPFD performs (along with quality comparison) and then having 3 data points I will be able to graph flowering phototropic efficiency by PPFD. More data is better so feel free to provide your gppw numbers along with the corresponding PPFD. I suspect the actual sweet spot is going to be in the 600s, but if quality doesn't suffer at 500-550 then that idea will need to be re-examined.

Bonjour
So what do you think about 4 cxb 3590 @1400mA over a 3.5x3.5x4.5???
I will chop soon...1/1.5 week!
I will let you know the results in 3/4 weeks!
CU

I come up with 475 PPFD and 111 par watts. Will be very curious what the yield is, thanks!

Need to know if soil or hydro.

Bonjour
It is organic soil and amendments (first time! I used liquid organic nutes before!)plus tap water! 3gl pot...5 plants.
I will let you know soon
And I am in 0.7/0.8gpw range with my 600hps.
CU

I'm not sure if I can accurately combine soil and hydro results, but a lot of people grow in soil so I should start two lists. I think maybe having it's own thread would be good.

Bonjour
I agree with this...you definitely don't have the same results with hydro...the best yielder I know use sure to grow as medium and have crazy results!
CU