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Totally true outside too. There is an engineer around here building power solar greenhouses showing hard evidence of his plants growing better under diffuse light (covered by a semi-transparent collector) than stressed by direct sunlight.

Thank you for the detailed answer. Yes, I saw the new Q series, and am very intrigued. My target for any future build would be 200lm/w @4000k and 40-50°C max.

Yes, but than we are back to the days of expensive cxb 3590 severly underdriven = just too expensive, if you ask me. The astonishing thing about those samsung series, is that their efficiency is given for 40% of their max. capacity (240ma/600ma) - at least theoretically.

Do you have a link to the thread ? WOOT: 187-206lm/w for the samsung h series ? Has that been verified empirically ?

Interesting reply, even though I would love some spreadsheet to sustain your claim. Also, it leads to the manufacturers question: dunno about you guys, but to me, it looks like a jungle of led strips out there. It's really complicated to get your hands on some reliable documentation about...

Yes, just search some of my posts. Here you can find some photos of my current track lights: https://www.rollitup.org/t/heatsinks-for-diy-led-lamps.851907/page-62#post-12015456 The aluminium heatsink offers 23mm diameter surface to attach the cob, which fits exactly even cree cx3070s. Though the...

Hello, It's been a while since I checked upon the latest development in growth LEDs, though I noticed that more an more people are experimenting with led Strips. Back in 2015, when I came up with the first citizen COB in this forum, it was all about single, powerful, under-driven chips to...

Doesn't this only work with symetrical current ? My setup has different currents. This would mean different transistors + resitors - I'd rather go with a ready to use module.

Alright, the problem with the simple-meanwell-parallel driving seems to be double for me: on one side, there is still the possibility of a (small) thermal runaway, and on the other side, the setup does not give enough flexibility. I don't know about you, but over time, I accumulated various COBs...

I'm thinking of running 3x cxa3070 in parallel with HLG-150H-42 driver; should have enough headroom. Anything I should think about before actually building it ?

Interesting feedback. Do you use any balancing circuits (like mirror current or simple resistors) ? Only constant voltage driver ?

Not sure the cat would appreciate it :P, but thank you for your fast reply. Simplest option (for me) seems to be the constant voltage driver. Would it work with something like this one: http://www.meanwell.com/webapp/product/search.aspx?prod=hlg-150h Anyone succeeded in doing so ?

Hello, I'd like more informations about parallel setup of high power cobs. Could someone help me out ? From what I read, the main drawback is thermal runaway, which, if I understand it correctly, means as the cob heats up, its vf lowered, which means it hogs more juice, heats more... and so on...

Never managed to stay at 50°C. 56°C is my best, @21°C ambient temperature. But than again, it's all passive. Usually, my lamps start at 52-54°C in the morning, and reach 58°C before shutdown, 12 hours later. The 1212 is another story: less powerful, but also cooler: this one stays @50°C. Had...

Not so sure about this one. I have two lamps hanging next to each other, one cxb3070 and one clu048-1818, both 5000k, both 50W. On my cheap luxmeter, the citizen is around 3% brighter, and 4°C cooler. Since I'm running everything all passive, the latter makes quite a difference. Not bad for a...

Sorry for the typo, I obviously meant 4-5°C. cxb3590 are way out of my price range, and in my opinion, not really interesting for diy setups. CLU-048 (former 046) and cxb3070 happen to have the ideal LES size to refit commercial tracking lamps = heatsink, lens, reflector, holder, support all...

Have you seen the update on citizen cobs ? Now version 5: http://ce.citizen.co.jp/productse/info.php?no=107 Not much of a revolution in terms of watt-to-luminosity, but nice decrease in thermal resistance. That's truely where citizen shines: they are easy to cool. My clu-046, now running for...

1. I work with track/down lights. Doesn't cost more than DYI coolers, and saves me a lot of hassle. Most are fitted with reflectors and heatsinks able to carry max. 22-23mm LES cobs - so the switch to high power citizen or cree matching that size is possible, but not when using 3590 for a...

I've been testing CLU046 - 4000k ra80 @1000ma, and so far, I'm quite thrilled. 3°C cooler than cxb3070 in a similar setup, and the light seems brighter. Will need a PAR meter to confirm the last part. Given the chip is 20€/pc around here, it's a clear winner for me. Also, holders for cxb3070...

Actually in most diy setups i ve come to see, poor connectors were probably the main source of power losses, not the wires. I basically solder everything, but never use wires with section larger than 0.75 or 1mm2. Full copper 1.5mm2 is just a pain to work with.