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http://www.treehugger.com/sustainable-product-design/leds-go-residential-and-theyre-pretty-cool.html
Posted from WordPress for Android
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Tomi Engdahl says:
LED light guides deliver affordable OLED-like performance
http://www.edn.com/electronics-products/electronic-product-reviews/other/4439192/LED-light-guides-deliver-affordable-OLED-like-performance?_mc=NL_EDN_EDT_EDN_productsandtools_20150420&cid=NL_EDN_EDT_EDN_productsandtools_20150420&elq=cd8175fad764408396c930b8d6c13bb9&elqCampaignId=22634&elqaid=25457&elqat=1&elqTrackId=1c15dcd57e1a4cd28ed0c03840f22746
Sleek, stylish and seductively luminous, it’s hard to resist the visual impact of OLED panels. Their silky, eerily-even glow has made them a favorite for fashion-forward lighting designers, even though they cost more, were shorter lived, and more easily damaged. This may change however, as Global Lighting Technologies (GLT) introduces a growing number of products based on its edge-lit LED-based light guide technology. Their latest product, a 4” x 4” LED-based light guide, was developed specifically to demonstrate the technology’s higher efficiency, better durability, longer life, and lower cost than a comparable OLED panel.
Tomi Engdahl says:
Cree Wants to Make Your Office Lighting Less Ugly
http://www.wired.com/2015/04/cree-led-lights/
No matter how much headway LED lighting makes in your home, you’re still likely stuck with unsightly fluorescents at work—or pretty much anywhere else you spend most of your indoor waking hours. A product from LED specialist Cree hopes to change that, using a new kind of optical technology to save you from the washed-out grossness that plagues cubicles everywhere.
Cree’s new LN series suspended LED tubes are similar to the fluorescent counterparts you’re accustomed to, at least until you turn them on. That’s when they trade the familiar jaundiced glow for the softer, more palatable hues that have made LEDs a legitimate alternative to incandescents bulbs, to say nothing of more garish corporate fluorescents.
The aesthetic benefits aren’t limited to the lights themselves; the LN light fixture simply look better than the buzzing overhead blocks that fluorescents call home.
That’s not to say the LN series is the first suspended LED lighting solution destined for offices; Phillips offers a handful similar options as well, as does GE. But Cree vice president of product strategy Gary Trott points to his product’s efficiency of 110 lumens per watt, compared to the 70-90 lumens per watt you might find in a comparable fluorescent tube. Perhaps more importantly, the LN series incorporates what Cree is calling WaveMax, a new technology that purports to allow for more customizability without sacrificing efficiency.
That granularity is matched by simplicity; the new Cree LN series also works with the company’s SmartCast technology, a plug and play smart lighting controller.
As LED costs continue to decline and the ease of use of money-saving smart systems continues to increase, our least palatable, most pervasive lighting will eventually give way to something brighter, softer, and, over a long enough time horizon, cheaper.
Tomi Engdahl says:
The Brighter Approach: Digital LED Drivers in Legacy Applications
http://www.eeweb.com/blog/eeweb/the-brighter-approach-digital-led-drivers-in-legacy-applications
Compared with incandescent or halogen lamps, LEDs have long promised much greater efficiency, cooler operating temperatures, lower CO2 emissions, and substantial cost savings—at least over the longer term. But as soon as people started to retrofit them within existing infrastructure, the limitations of LED technology became apparent.
LEDs in MR16 packages are designed to replace 12 VAC halogen lamps. These lamps are often used where the presence of grid-level AC voltages is undesirable.
Originally, step-down magnetic transformers were used to achieve the required voltage drop, but in the interests of efficiency, electronic transformers are now more common. Installations vary, but in most instances, one transformer feeds one 25W to 50W halogen downlight. Most of these transformers are designed to work with a resistive load of at least 20W.
An 8W LED bulb, with roughly the same lumen output as a 40 or 50W halogen, is an insufficient load. As a result, the LED either doesn’t function at all, or just flickers. One solution has been to add an active or passive bleeder circuit inside the LED housing. Active ones are a little more efficient but both options significantly compromise overall efficiency. What’s more, both involve adding components to the lamp—adding cost, size and complexity—and both generate heat, which has to be dissipated from the assembly.
Critically, the life of aluminum electrolytic capacitors found in almost every LED driver circuit is halved with every 10°C rise in temperature. It’s these electrochemical components that are the main culprits in limiting the operating life of an LED bulb.
Mainstream TRIAC dimmers work by cutting off part of the sinusoidal mains waveform to reduce the RMS voltage powering the lamps. They either cut the leading edge at the start of each cycle, or the trailing edge towards the end of the cycle. Dimmers are further classified for compatibility as R-type for tungsten-filament (GLS) or high-voltage halogen lamps, L-type for low-voltage halogens connected via magnetic transformers and C-types for low-voltage lamps running from electronic transformers. To add further complexity, the dimmers can be R-type, R-C types, RL-type, or RLC-type, depending on how many types of lamp they’re compatible with.
As with step-down transformers for low-voltage lighting, dimmers based on TRIACS need a minimum load.
Tomi Engdahl says:
Home> Community > Blogs > BenchTalk
My kingdom for a 12V adapter
http://www.edn.com/electronics-blogs/benchtalk/4441809/My-kingdom-for-a-12V-adapter
Our new house is inching towards 100% LEDness, from LED “bulbs” in standard light fixtures, to custom LED lighting, to flexible LED light strips. It’s the latter I’m having some problems with.
After some preliminary research, I decided that the only affordable sources for LED strips would be from among the numerous Shenzhen & Hong Kong mega-retailer Websites. There, you’ll find standard 5m LED strips in the $4-$20 range, instead of the $50-$100 range typical of other sources.
After some preliminary research, I decided that the only affordable sources for LED strips would be from among the numerous Shenzhen & Hong Kong mega-retailer Websites. There, you’ll find standard 5m LED strips in the $4-$20 range, instead of the $50-$100 range typical of other sources.
With the LEDs themselves taken care of, I turned to power sources. In the basement, I’ll probably use some centralized high current 12V power supplies..
While I’m willing to accept some creative LED specs, I do expect a 5A adapter to be a 5A adapter. Silly me. They turned out to be more like 2A, and to add insult to injury, the output cables appeared to be vastly undersized