I haven't heard anything about this, but I had an idea that LEDs could have a huge potential to replace fluorescent and/or incandescent bulbs, right? They use less electricity, have a variable amount of light if needed, and won't generate extra heat. They're making flashlights out of them, why not household bulbs?
They tend to blink a lot unless a extra capacitor is added to the circuit. Cost is another factor but yes they use a lot less power and last an extreemly long time. They could be damaged by power surges if not connected properly. I ran one off a single AA Li-Ion cell for 5 months 24 hours a day not very brightly of course but a pot connected to it would allow me to dim it very low with extreemly low power like 12 microamps.
LEDs should get cheaper to buy as more are sold. As the link mentioned, traffic lights and flashlights have been recent practical applications -- so if the trend continues, cost should come down over time.
(I am by no means an expert in electrical circuits, so some of the following may be completely off-target)...
Unfortunately, as in traffic lights and flashlights, the beam is straightforward. If you needed to light a room, a wider view angle using a group of relective surfaces (or collimators) could make a common "Type-A" bulb from a narrow-angle set of LEDs. My concern is that people like instant plug-n-play compatibility with existing hardware -- like the screw-type fluorescent bulbs that fit most sockets today. A 110VAC, 20-Amp light socket would have to be stepped-down to the DC micro-amperage of the diodes -- step-down transformers are generally large, produce heat, and waste energy. A die-hard installer could probably do this at the light switch, including capacitors and by using existing wiring if a mulitple-bulb circuit is switched. Surging hopefully could be squelched by the combination of a transformer with resistors to achieve the right balance. I'm thinking of a rheostat to vary the brightness on hard-wired fixtures, and maybe a similar knob on lamps or independently outletted items (if the beam is too strong). Even a soft-white lens could tone-down the stark-white quality of the light.
I know lighting probably contributes to a fraction of a home's energy usage these days, but replacing incandescents has to help in more ways than one. Someone needs to get going on the Type-A bulb idea. I'd experiment myself, but I can't solder worth a hill of beans -- actually, I usually end up with a mound of melted parts. A ready-to-go bulb would need to get into Ohm's law equations and, as mentioned, capacitors and some way to protect from surges. Any electrical engineers out there to prove this impractical?
The typical LED shoots a 20 degree beam but if you frost the end of the led it will diffuse it more or you could glue them into a ball. Wire a bunch in series in two strings in opposite directions and add a diode to each end and run them back to back so it draws power on both the positive and negative swings of the AC power to keep it balanced. This will also require two caps to filter out the ripple and keep them lit constantly. You probably should use a full wave bridge and a single long string of LEDs and single cap. LEDs that are white light up at about 2.5 volts so 160 / 2.5 = 64 in series to light up with 120 vac with a little resistance in series to limit current. Less could be used with larger resistance and a dimmer would be really easy with a 100k pot without any Triac. 180 / 2.5 = 72 would probably be the max amount of LEDs in series.
I've owned a edison base "warm white" LED spot light for a few months now, said something about it a while back, I forget where, I ordered it from http://superbrightleds.com they have a whole section of LED's that have built in powersuplys/controlers so they can use 120VAC, the one I got, a spot light, was disapointing, it was a single 1watt warm white LED, who's power controler used close to 1 watt as well, so it drew just under 2 watts acording to the kill-a-watt meter, less then my clock radio when it is just telling me the time.
my thoughts on this product? it's really neat, if you had a track light focused on something, or a desk lamp that you wanted light just focused on one thing, it would work great! it's more then bright enough to read by, the warm white is slightly yellow, not blue-white, so it's what everyone is used to for electric lights, but if you have it focused on a news paper, the only thing you will see in the room is that news paper, there is no extra light! next time I place an order, and feel like tossing another $20 around, I'll order another one, but not the single LED spot light, next time it will be the multi LED light, something to replace the 9watt compact florecent that stays on half the night for anyone who comes home after dark.
also, to varify that LED's really do last as long as they say they do, I know a guy who has had the same 3 white LED's wired up, and lit for the past 6 years, without turning them off once, hard wired in to a 12 volt battery bank, one in his living space, two out side his front door.
I've bought a handful of nitelights and undercounter puck lights from superbrightleds.com Good stuff there.
The warm whites are very nice- although, as pointed out, all LEDs are very directional without a diffusing lens around them.
The nitelights and appliance bulbs are only in cool-white, and my family doesn't care so much for them. The ones with candelabra bases are much dimmer than a 4W incandescent nitelight, but enough to do the job.
CFLs are the way to still go for general lighting; with LEDs good for accents or task lighting. Still cost prohibitive in some cases, especially when they pile more than 10 or so onto a fixture for higher output.
Organic LEDs (OLEDs) are coming down the pike- cameras use them now- and they'll be dirt cheap after some manufacturing yield issues get solved. OLEDs will take the lions' share of the lighting market from semiconductor LEDs, so LED lighting prices may never get comeptitive at all. SOmething to keep an eye out for.