High Efficiency LED for Joule Thief, etc.

[ramset]

Soo
would you care to guess ?? [to the trained yet uncalibrated eye ]

watts per square foot of growing space [for lettuce]
lets see how close you get .

since I will be looking into this with the manufacturer , [Phillips and others]

[MarkE]

Soo
would you care to guess ?? [to the trained yet uncalibrated eye ]

watts per square foot of growing space [for lettuce]
lets see how close you get .

since I will be looking into this with the manufacturer , [Phillips and others]

A quick survey suggests an upper limit of 600 PPFD for lettuce.  To translate that to Watts you have to go through the efficiency of a particular lamp design.

[TinselKoala]

I'm presently testing a MXA8-PW30-0000 LED (see data sheet attached below.)
These have a color temperature of 3000K, rather than the 5700K unit
shown in the videos I linked up above.

At 80 mA, just over 3V, straight DC, it's like a tiny sun it is so bright. It leaves purple spot
afterimages, I can't look directly at it, so I have it pointed away, down at the floor. 

It does get perceptibly warm but not enough to need a formal heatsink yet. In a little while
I'll run it up to 100 mA and see if it lasts.

It runs my "perpendupetulum" light powered pendulum quite well, from a foot away from the PV cell.

[MarkE]

I'm presently testing a MXA8-PW30-0000 LED (see data sheet attached below.)
These have a color temperature of 3000K, rather than the 5700K unit
shown in the videos I linked up above.

At 80 mA, just over 3V, straight DC, it's like a tiny sun it is so bright. It leaves purple spot
afterimages, I can't look directly at it, so I have it pointed away, down at the floor. 

It does get perceptibly warm but not enough to need a formal heatsink yet. In a little while
I'll run it up to 100 mA and see if it lasts.

It runs my "perpendupetulum" light powered pendulum quite well, from a foot away from the PV cell.

Those LEDs are a real treat.

[TinselKoala]

Here's a surface brightness comparison. The A19 LED bulb in the desklamp is a "60W" equivalent, rated 800 lumens, soft white 2700K "EarthBulb" brand. The test LED is a MXA8-PW40-0000 high-efficiency LED with a 4000K color temperature, running at 95 mA straight DC, held right up in contact with the A19 bulb. The camera image is taken at 1/500 second, f/32, ISO1600, with my Canon Rebel Xti DSLR. To the naked eye the tiny LED is much brighter than the equivalent surface area of the A19 bulb, and the camera tells me the LED is actually overexposed in this image.