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Pretty plant! A friend with a "270W" UFO found it actually put out ~85W at the LEDs, if so I'd put it real close!

How do you smelling folk* recharge your activated charcoal? Solvent extract? Pyrolyze? * I got anosmia

I haven't seen Cree's data but there is an argument that "the most perfectly engineered light that we would perceive as “white” cannot achieve much more than about 250 lm/W" see: http://physics.ucsd.edu/~tmurphy/papers/lumens-per-watt.pdf Since the silly lumen scale is centered in the green...

The durability of the QDs (where I've seen data) hasn't been up to the std phosphors, they quote some 2000h lifetime at 110C but at reg temps they have been inferior. Maybe this has changed but it was of note when I saw it. QDs were "the next big thing" about year 2000 but many of the companies...

FYI here is an interesting presentation on dimming LEDs http://www.lutron.com/en-US/Education-Training/Documents/LCE/LightSources/LED/Dimming%20LEDs%20-%20LFI_2012_v1.01.pdf

Nanoco (with DOW) is a pioneer in this area, but Quantum Materials and Nanosys are still making tons of Cd containing QDs. On the bright side the Cd is sequestered in a durable shell, but the toxicity once released is well documented.

As to phosphors there are things called quantum dots (QDs) which are tiny semiconductor beads made of layers of (usually) cadmium and selenium that at least one company QD Vision / Color IQ is trying to add to display screens. Traditionally white LEDs were YAG:Ce phosphors combined with...

yeah the $/lb is pretty loooow. I ran across an organic / hydroponic basil production facility in SE Portland, they used 100% MH lights and had some pretty leggy plants, They gave me about 100 pulled plants for the price of the rubbermaid tote (5$) that I used to make 5 Qts of pesto and start my...

I appreciate that! I often find its easier for me to dig the same hole deeper but every so often it pays to dig a different hole entirely; gotta keep an open mind! (credit to Edward de Bono on the hole analogy)

Here is a 2x5 6063 tube I polished up in 15 min with a cheap HF 5" random orbit sander hooked to a Shop vac A is mill finish from Coastal Aluminum (lots of extruder die striations visible) B is after 100 grit-> 220 grit gold aluminum oxide C is after green Scotch-Brite pad-> purple...

Another good value LED apart from small high wattage COBS are the (getting better) LED based fluorescent tube replacements. Like the Luceco LED Fluorescent Replacement Tube - 4 FT - 24 Watt - 2400 Lumens, available at EarthLED and a few other places...

Sounds good to me, ideally both surfaces but usually people use overly large heat sinks that compensate for imperfect interface, we're not working on the ragged edge of performance so extreme measures aren't required. Hardcore stuff uses fancy surface grinders with diamond lap and maybe diamond...

They are 50W 50LED array COBS with 40 red LEDs and 10 blue LEDs but I haven't measured their spectra with my $10 spectrometer yet!

With heatsink mounting surfaces you are very interested in absolute flatness as well as surface finish, so its very useful to use a granite flat* with silicon carbide (SiC) paper stuck down to it with spray mount (best) or double stick tape for final lapping. In a pinch a thick piece of glass...

I used to use something similar then I found scotchbrite metal finishing pads from Homedepot (2$) will stick right to a hook and loop (velcro) random orbit sander (with vacuum for dust!) and produces a good finish on aluminum*, nicely removing the embedded grit left by water jet cutting. For...

My Genovese basil is doing quite well under 250w of Blurple, hard to photo but its tasty

Thanks Mark! A good quality pot would be the Bourns 3360 series, 3360Y-1-104LF (50k, $3 at Mouser) or 3360Y-1-503LF (100k, $3.75 at Mouser) all IP67 with a 0.25W conductive plastic element, these cable mount nicely with soldered wire (to PC pins) and inner melt heat shrink or panel mount and...

Dimming is useful if you want to work under the lights and not be blinded ;) I don't buy the natural sunrise/sunset mumbo jumbo that KIND LED spouts. I have a specific Bourns pot model (oops "potentiometer" here) that I like, IP67 sealed, conductive plastic element, $3 but Cutter will only...

its often very difficult to get accurate data on Chinese purchases before they arrive, these state "60W" but the ad also says: "0.7A at 22Vf" (=15.4W) and "1.4A at 25Vf" (=35W) realistically these are 24Vf modules that make 28W and if so they are probably a 10S2P array of 2.2V...

For a simple hook up you have to go with 15W LEDs to use 28V, or do some fancy series parallel stuff. 18 x Vero 10s (BXRC-40E1000-B-23, $4.14 ea. at Digikey) plus the $29 PS would give a $103.52 setup with 34,000 Lm at a very good 327.61 Lm/$ and 2.72 W/$ (before rails etc) but its a bit of...