Wow, are those single-chip, or “cram as many LEDs into a bulb shape as possible”?
Maybe someone with a diffraction grating can test LED bulbs to see how many phosphors they have. Here’s one I did of a fluorescent lamp: https://lh6.googleusercontent.com/-rQPfqyvWs7U/UYPUZlgkvWI/AAAAAAABQX4/R4odJUYYUfQ/s800/CIMG2880.JPG
sort of the latter. they’re not the uber-cheap “corn-cob” types you’ll find in the bargain bin and dollar stores (which are incredible pieces of junk) but they use multiple diodes and diffusers to get pretty close to omni-directional.
I can’t find my Sylvania one now and I have a residing project going on. When it turns up I’ll see if I can take pictures.
Some bulbs, including Home Depot’s EcoSmart and others, have been recalled due to fire hazard.
For folks that are REALLY interested in this stuff. Years ago I recall running into of all things nerdy a forum devoted to high power LEDs. That’s way back when LEDs were starting to replace flashlights, not light bulbs. Candle forum or Candlepower forum or some such. If you are that interested I’ll let you guys search around for it yourselves.
I can’t find the page I read it on, but as I recall the specific run of bulbs being recalled were prone to coming apart due to improper assembly (thermal cycling would loosen the assembly and cause it to fall apart.) Hardly an indictment of the tech.
It was a PSA, not an indictment.
apologies, my misinterpretation.
I obviously haven’t done a comprehensive review, but here’s an interesting demonstration that might explain why LED light is subjectively poor quality. Here’s two red traffic signal lenses, with a 60 watt bulb on top and a 60 watt equivalent LED on bottom. Notice how little red the LED produces compared to a real bulb.
https://scontent-b-ord.xx.fbcdn.net/hphotos-prn2/1450774_10151974767199875_1539459005_n.jpg
In the case of traffic lights, it looks like they use a white incandescent or LED bulb and a red lens. So if you want to replace it with an LED equivalent, wouldn’t you get better and more light if you used red LEDs and a clear lens?
Then I promise you don’t want to replace a pool light. Mine was out and the drawback to using conventional as opposed to LED is that the filament gets hot, increases the internal temp and pressure and then draws a vacuum when it cools. Not good in a pool and water will eventually find a way in. Obviously with LED this isn’t the case. The bad thing is LED is twice the price, in this case $800 installed. Each. Ouch.
That’s exactly what I did, and traffic lights do use red LEDs, not white. Demonstration I was trying to make is current “white” LEDs suck at producing certain colors, not duplicate what an actual traffic signal would use.
This was a fun and informative thread (hey, I’m a nerd) and I missed it the first time. Great info all!
I’ve always wondered why LEDs had a heat problem even though they were more efficient. Other than a fire hazard is there a problem with LEDs heating up? Say the LED is mounted in an all-metal/ceramic housing and nowhere near anything flammable.
That’s another problem in that LED manufacturers always show their product in a large standard table lamp, like that’s all people have. They might look funny, throw light sub optimally and/or burn out from the heat in other types of fixtures. Some of the LEDs are approved for use in enclosed fixtures, and some aren’t.
The heat problem is mainly when compared to incandescent (and halogen). Incandescents shed their heat in the same direction as their light, which gets radiated out into the room space with very little transferred into the back side of the fixture.
LEDs are the opposite, nearly all of the heat is shed into the back of the circuit die and board, and needs to be transferred out the back of the fixture or the circuit board components will overheat and fry. Traditional light fixtures (say, a ceiling lamp) might not allow enough heat flow, and the LED will have a problem (failure, fire, etc).
If you can shed the heat enough to keep the LED circuit in its “happy zone” of operating temperature, they can be used anywhere. Heat sink tech and materials are a very big deal in the industry.
The main problem is that the LEDs themselves, and associated electronics, don’t like the high temperatures. If you were willing to pay enough, you could probably get more durable components–no electrolytic capacitors, etc. But this would add greatly to the cost. There’s also an LED bulb out there that has a fancy internal liquid cooling system, but it’s just so expensive that I don’t see it being practical. For now, the only way to keep prices semi-sane is to make a few sacrifices in mounting flexibility.
Thanks, you guys rock. I’m in the (slow) process of creating my own light fixtures out of vintage cameras using LEDs. If you guys are willing I’d love to get some advice on solving some problems.
