Astir Grow Led Panel Project...

PSUAGRO. said:

Great job Ganja!! Impressive................how much does that thick clear plastic bag weigh???

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HiloReign said:

I believe he weighs it in the first two pictures. I think it said 21.2g. I may be mistaken...

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Phosphor converted white LEDs are becoming more and more attractive for general lighting applications because of the steadily increasing luminous efficacy numbers reported by LED-suppliers. Despite these high numbers, a further significant improvement step can be made when a low-to-medium brightness (<500 kCd/m[SUP]2[/SUP]) source is acceptable. The wall plug efficiency of a blue LED is generally better than that of a conventional white LED made from the same die. To take full advantage of this, we have developed medium-brightness LED-modules (~150 kCd/m[SUP]2[/SUP]) for general lighting in which the phosphor is applied remote from the blue LEDs. By direct comparison with modules in which conventional high power white LEDs with almost identical dies are applied, we have shown that on system level the remote phosphor modules can have up to 50% better efficacy. Using a downlight module as a carrier, we have shown that in the relevant color temperature range of 2700 to 4000K a high CRI (>80) can be obtained in combination with a high luminous efficacy, while the optical efficiency of the module can be over 85%. A module efficacy of over 100 lm/W at 4000K with CRI 80 seems to be within reach, with a long-term expectation of over 180 lm/W. The remote phosphor LED modules deliver well homogenized white light with a Lambertian radiation profile. They are ideal for general illumination, as they combine glare reduction with high system efficacy and enable high optical efficiencies of the luminaries. The RP modules enable forward compatibility by well defined interfaces and optical properties that are decoupled from the actual performance, form factor and number of LEDs in the module. The Philips Fortimo downlight system is based on this remote phosphor concept, featuring forward compatibility and a total system efficacy (including driver) of over 60 lm/W under operating conditions using currently available Luxeon Rebel emitters.

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Remote phosphor technology is another approach you can take in creating your LED lighting application. The technology of remote phosphor light source element is achieved by bonding phosphor to a substrate, instead of incorporating it into the LED die package. Combining the remote phosphor plate with Royal Blue LEDs, and a mixing chamber, white light can be achieve with no visible point sources. This approach provides a low glare system capable or higher system efficiency, increase reliability and less color shift over time.

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Thermal color stability

The application team also measured color shift of the tested lights from the chromaticity at 25°C to that at 85°C. We won’t detail those results here, although they will be available at a later time on the Cree website. But we will summarize the results.

FIG. 4.

In the case of the white LEDs, the phosphor is placed on the LED chip. The phosphor temperature can therefore be very close to the junction temperature of the LED, around 90°C when the heat stage is at 85°C. The conversion efficiency of the phosphor can drop with increasing temperature, thus there will be less yellow light from the phosphor and the overall LED color will shift toward blue. Generally speaking, the remote-phosphor systems don’t exhibit as much color shift over the temperature delta. Of course the lamp or luminaire design team can easily accommodate color shift by testing products at temperature. Moreover LED component vendors such as Cree are increasingly binning components at 85°C so the product designer can be assured how the components will perform in application.

FIG. 5.

Given that our tests with remote-phosphor systems in different configurations have shown increased light output, you may think that the approach is clearly superior. Our tests were comparable to actual applications such as a recessed downlight, or a lamp in a pendent or a wall sconce. But the evaluation doesn’t end until we consider why the remote-phosphor system showed an advantage and consider the cost tradeoffs of each approach. How it works
In an integrated white LED, the phosphor is very close to the chip, either as a thin coating or embedded in a silicone encapsulant matrix. The blue light generated by the LED chip emits in all directions. Some of the light rays will interact with the phosphor on the LED chip resulting in a conversion into yellow light. Actually the converted light consists of many different wavelengths, but the spectral distribution is primarily yellow. These yellow rays are also emitted in all directions and some of them will reflect back to the LED chip and be absorbed, resulting in an efficiency loss (Fig. 5).
In comparison, in a remote phosphor system, the phosphor is placed far from the LED chip. As the blue light reaches the phosphor and excitation-emission process occurs, the yellow light from the phosphor emits in all direction as in the white LED, but since the LED chip is far away, the chances of these yellow rays hitting the chip and being absorbed is significantly lowered. As long as the remote phosphor system is well designed with a high-efficiency reflector that redirects yellow light reflected downward, the overall efficiency in a remote phosphor system will be higher than in the case of the white LED.

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weedman420gr said:

A pop up question real quick...

SDS,do you think that the 1-1.5(2.0max)g/w ratio can also be reached with a smaller number of panels * ? ( 2-3 for example) (*and ofc a smaller number of plants)

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I'm thinking just mixing phosphors ,a strong but volatile organic solvent (i.e. chloroform )

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Any DIY method that is sufficient enough and efficient for bonding Phosphors with PMMA and/or Polycarbonate screens ?

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