Archive for January, 2009


4,000 lumens in a package smaller than the face of an MR16 lamp has interesting possibilities, and some issues to contend with

Luminus just announced the offering of  a configuration that pushes over 4,000 lumens in a single packaged device.  The company claims include the use of a Photonic Lattice technology to increase surface brightness and uniformity of the device. The result is a 6mm x 6mm area LED with exceptionally high output.

This all sounds great on the surface (no pun intended), and may be for a few special applications. Here is my own view of products like this:

First: 6,000K is not “cool white” it is beyond daylight white at best and has very limited usefulness for interior illumination.

70CRI is not good enough, period, no matter how much light is being cranked out.

The combination of 6,000K and 70CRI puts the application space for this product in factories, garages, outdoor areas, and warehouse locations, where cost will be a huge issue. The potential for long life may be its biggest asset here, in operational expense over higher maintenance HID products. However, this puts it squarely against 250W and 400W Metal Halide, and 50,000hr T5 lamp technologies – systems all producing well over 20,000 lumens, at very low initial cost.

+/- 32 lumens per watt efficacy is simply not good enough (assuming a raw 34 l/w at a power factor of 75% with a driver/power supply efficiency of 88% and ambient operating temp of 45C). This compounds the thermal design issues raised by its small size . (more…)


Now that the office is 100% LED, including a retrofit of the pendant, a retorift/remodel of a Kovac Feather task light to LEDs, and a custom copper tubing linear wall washer - all white now... its time to step up and get into this color thing head first.

I miss the simplicity of low voltage halogen lamps. Must be getting old… A lamp, socket, transformer, a few bits of shiny metal, a switch from anywhere, maybe a sliver of glass, a transformer, couple lengths of wire… clean and simple. LED projects are a bit more complex, especially when you want to incorporate color in the mix. I tried a few white only LED designs and found them… well, common and boring. I’ve retrofit most everything to LEDs, from decorative to work lighting using white LEDs, my office is 100% LED now, the house is now 75% LED, 20% CFL, and the remaining halogen lamps, soon to be disappeared in favor of new LED products of my own invention. This has all been fun, but the end result is not that much more than I had, short of the energy saving. This is not what I believe in, it’s just the easy way out.

So, the next step…  (more…)

While I appreciate and am an enthusiast for SSL, my personal interest extends beyond the white light universe. I personally belive that in the very long haul, fixed white light will eventually give way to blended color, specifically R+G+B+W. Actually, more like Red Orange + Green + Cyan + 6,500K White . In either case, this approach has the potential of producing the complete white light tonal range, pastel soft light colors, interior color tuning, and exterior vision enhancement. Above all, these combination create the potential for the deployment of “Visual Efficacy” we have not yet had an opportunity to approach. (more…)


A 120V AC LED may be a good choice where power supply and driver cost and component complexity is an issue.

An LED that runs from 120V AC (o0r 240VAC) is an inciting item in the solid-state low voltage DC universe. No driver, no transformer. Just plug it into the house current and let ‘er rip! Available in 2W 65l  (3000K) / 80l (6300K) and 4W 150l (3000K) to 195l (6300K) versions, these devices are fairly powerful and generate good efficacy (between 32 and 40 lumens per watt), not bad, considering there are no other power losses involved from voltage conversion and driver/conditioning. This is roughly the performance of a 50l/w 24VDC CC device operated from a balanced and high efficiency driver/power supply. Not bad.

Color rendering index is 70. At the low end of the good range, and is caused by a weakness in the red end of the spectral distribution. Further, the peak power is virtually right on top of the 575-600 nm of photopic vision.  The result is that the 3000K light looks a bit “White” and less “warm” than one might expect.

To put these to the test, I retrofitted a pendant (in my office) (more…)


With the variety and performance of LEDs, the opportunity to be creative with them is unbound... except for the heat thing.

LEDs bring a lot of creative potential to the lighting market. At this creative front will be artists who apply them in unique ways outside the mainstream general illumination marketplace. I’m one of them in fact. Gone are my days of fooling with halogen lamps and transformers – now its LEDs, drivers and power supplies… and heat sinks.

The first wall hit in application of LEDs is their output and thermal dynamic. In halogen lighting, the fixtures got hot, no big deal. As long as it wasn’t peeling flesh or raising a blister, its was fine. LEDs don’t work that way. Long before the lighting portion gets hot enough to raise a blister, the LED is fried, game over.

Ultimately, the goal of an artist in creating a new work of light is to generate as much light as possible in the smallest, most innocuous package. That makes LEDs at once attractive, and a problem. To illustrate, a 350mA 1W LED requires very little thermal management to survive. Glue or screw it to plate of aluminum or copper and its happy. Problem is, the amount of light is pretty weak, between 35 and 60 lumens if you want 3,000k color with good color rendering (yes, artists do care about color – a lot.) That’s a long way from the 600 to 800 lumens we were used to in halogen sources. Optimally, for a task light with a good optic (wide smooth beam), gettting to around 350 to 500 lumens is optimal. This means more energy. At 700mA, 100 lumens is attainable, and lands us in the 3 to 4 watt range. Three is always better than 10, so this sounds like the way to go. Problem is, a 3W LED is exponentially more demanding thermally than that 1W device. These higher energy devices demand heat sinks, real life thermal management, with airflow and everything. (more…)

Objectivity is Relative

Posted: January 16, 2009 in General Commentary

For anyone who has read my contributions to Architectural SSL magazine, or Illuminate, this blog, my web site, or comments on various industry groups, one might believe I fail to remain objective about solid-state. In my defense,  I do simultaneously propose that solid-state is a technology that will lead lighting to all new quality solutions, while attacking product of poor quality, or of dubious value to the market sold on the momentum of interest that exists for LEDs.

To be perfectly clear – I am not an advocate of retrofitting conventional lighting in general – while it has its place in the near term, it fails to deliver the real value of LEDs, places thermal stress on a source thjat already suffers enough from that, and packages LEDs into lumps that give away the design value of solid-state in order to serve a market emotionally attached to the familiar and fearful of anything truly new. Retrofit CFL lamps are a failure, for exactly the same reasons. Meanwhile, fluorescent lighting, from small to large, is a huge success, based on new products developed to bring their unique capabilities to the market. (more…)

Post Ratchet LED Task Light

Post Ratchet LED Task Light

This is my very first functional LED task light, completed at the end of 2005. Construction is welded steel. Originally, the main components of this fixture (2004) were designed for a 12V/20W Halogen bi-pin lamp that created an overheating of the lighting head and poor light output. This was changed to (12) 1/2W Nichia HB LEDs (2800k) mounted to PC board with through hole thermal connection to the heat sink, as an experiment and proof of concept for the application of LEDs to provide greater light output for the same or less energy. Light on the task surface was either 70FC or 150FC, with a very wide distribution, as there is no secondary optical control. An aluminum heat sink inside the lighting head maintains reasonable operating conditions for the LEDs (under 60C TJ), while remaining cool to the touch. The horizontal arm ratchets up and down, the red arches are fiberglass springs that tension the ratchet. The parallel link on the head and arm keep the head level when it is adjusted up and down. (more…)