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Indeed Mean Well ELG drives don't do PWM on the output. They adjust the either voltage or the current, or both. PWM can be used on the input. The three ways of adjusting the dim setting (ie resistor, applied voltage or the duty cycle) are all changed into a voltage by the dimming circuit. This...

I agree. Have you done grows with Gavita DE 1000W at 24" above the plants? I did and it does cause bleaching. I had a pure white top. Besides, even at a low 24"for such a light, that's still 20" higher than well spread out leds have to be. In fact I let my plants grow through the frame even if...

Yes, with you it always is. You lack the capacity to really understand basic concepts and on the off chance that you do get it, you simply move the goal posts. Or just dump a shitload of random nonsense and pretend you "proven" something. Which is all now even made much much worse by the fact...

To prevent bleaching the plants? Good luck with that.

It's common knowledge that better spread out light sources better gives better uniformity Just try to think a little. If you were to spread 8 led strips of 112cm over a 4'x4'. How would you do that? Would you clump sets of four strips together in two narrow bands? No that clearly would be...

Apart from the point that that really isn't practical and that you will not realize "much better efficiency" with these planks at all. Fixed that for you Wrong and wrong. Those efficiency figures can just as easily be achieved by strips (2.5umol/J is even less than current strips will do at...

Wow, I missed that chart above before. So you pump in 1750umol over 4x4 (=about 1200umol average per m2) and then you are left with an average of only 826umol/s/m2? Which means that only 70% of the light actually reaches the plants. The rest is wasted on the walls because it hangs so high...

So for that 90 CRI model you get 2.11 umol/J @ 50W. Will be a few % more for the 80 CRI and a few percent extra for the gen 6. Still, with led strips and rectangular boards, people tend to be looking for around 2.5umol/J and up.

Well it's good to confirm ideas :)

Exactly. Like I said 3 posts up :)

I wouldn't push a Citizen 1212 to 40W. They are more suitable to 15W to 20W. if you want good efficiency that is. I mounted my COBs running at 15W to a standard aluminium bar. Six COBs per bar. Sort of created a COB LED strip. Buying led strips would be easier/better I guess, but if you insist...

Convection versus radiant heat yes. Important to realize is that the heat actually still is produced by LEDs. The trick is to not just exhaust it straight out of the grow.

What 1212ham said. HPS radiates heat onto the plants. You can feel the heat coming off those bulbs. With led not so much. Leds mostly give you convection heat. ie heat that rises up from the coolers. It rises away from the plants towards the exhaust fan and it's gone. That's actually why I...

Just use led strips instead. Much better light distribution than with QB's and you can buy them cheaper than QB's from reputable dealers.

Mixing led and 1000W HPS does not really work that optimal though.. You really need to hang that 1000W HPS quite high above the canopy. While the biggest benefit of led is that you can hang them quite close to the plants. Therefore minimizing the area of walls that you light up and lose photons...

Why not use Samsung led strips H-inFlux or F-Series gen 3. Or Bridgestone if you must. It's usually a lot easier to construct a light using led strips rather than using individual COBs

Plants/seeds do sprout faster when they do get light on the soil. Also, you should not change the height to adjust intensity. With the height you choose the spread and uniformity. There is an optimum height for that. After you put the light at the optimum height, then you should adjust...

Which one? There are a couple alternatives. For instance the DIN 5031 curves: Big difference is what they measure. The purple line is solely for chlorophyll. The other two for the two photosynthesis systems in leaves. Shinji Tazawa also produced action spectrum chart which looks pretty...

I have mounted COBs to aluminium strips. Works perfectly fine. The fact that people overkill on COB cooling doesn't mean that's how it has to be. Cobkits has shown four 1212 Citizen COBs mounted on a QB heat sink outperforming the QB on the same heat sink. With the COBs being cheaper than QB's...

COB's don't cost more. Plus they can be spaced out better than boards. Led strips are the best option, but I guess QB's kits are easier to put together if you really have no DIY skills (albeit more expensive).