I found the package for the Cree and the Sylvania and there is definitely nothing on either of them about not using it in enclosed fixtures. So maybe just go ahead and if it burns out make a warranty claim because they didn’t tell you not to do it. (The Philips does say not to).
I have a string of LED Christmas lights mounted in the office. I don’t mind the energy use of incandescent but I was tired of constantly changing bulbs since they’re apparently designed to be used a couple of weeks at Christmas and then thrown away. To get a string of LED lights that didn’t flicker horribly I had to pay close to $40.00 and order from a web site.
Looks like 250 mA @ 11.1 v to 1250 mA @ 12.25 v, so really a 1.15 v range. More importantly, that’s a quad-die module (in series). Individual dice still have a working range of a few tenths of a volt.
it all depends on the thermal management. The “EcoSmart” (Home Depot) bulbs come in two forms, the “sno-cone” type like this says not to use them in enclosed fixtures. The omni-directional ones like this are suitable for enclosed fixtures. Note how much larger the heat sinking is on the latter one.
I’d love to see good LED spotlight replacements for the “can lights” that are so commonly installed in ceilings these days. We have CFs in the ones in our kitchen and I must say they completely suck. Their lifespan is far shorter than expected (we’re lucky if one lasts a year), and they take forever to warm up and actually light the room.
And 3-way LED bulbs - when are they coming??? I have several lamps that have 3-way but won’t handle a 3-way CF.
They do make LED flood lights (don’t know about spots) and an even neater way is to replace your trim with an integrated LED replacement, Cree and others make these.
I’m actually struggling with the issue. I’m putting in 20 cans in my basement. LEDs would be expensive upfront, the light quality isn’t as good and the dimming ability is even worse, but twenty 65 watt floodlamps would not be inexpensive to operate.
Yes they do. I replaced my 75W exterior floods (4 of them) with 14W 120 degree throw lamps and I have to say I don’t miss the incandescents at all. The cut-off is much sharper and the light is more evenly distributed. I also replaced the MR10 track lights (10 of those) in my kitchen and have been very satisfied with one minor caveat. Initially, I bought direct from a Chinese factory and the bulbs didn’t even last two years before they crapped out one by one. I have since bought Cree replacements and they have held up much better.
I’ve found the same thing. I replaced some flood CFLs with Philips LED can lights. It look a bit of adjustment, as the light is a bit whiter and the edges are sharper, but I like the effect overall. The fact that they turn on instantly instead of ramping up over several minutes is a huge deal.
They probably won’t pay for themselves over and above the CFLs, but the usability is leaps and bounds above, and they should at least last longer.
I design LED stuff also…PWM chips and regulators are dirt cheap nowadays, and the best way to dim without noticeable flicker. The gory detailshere, but basically you have a circuit that creates a DC square wave at whatever frequency you want. You then dim by controlling the width of the square to control the time the LED spends in an ON vs OFF state.
The tricky part is, as always, squishy fleshy humans. Everyone perceives flicker at different sensitivities, ages, and differently across lighting color ranges. In my case, I can see PWM flicker at upwards of 150Hz if in the blue/purple color. If white or yellow, it usually disappears around 80Hz.
Making a light pleasing to everyone is the hardest challenge.
Since you make LED stuff, could you answer why they can’t make LEDs that dim the same way as incandescent, maybe even turn off individual emitters if there’s a technical minimum brightness for a emitter to fire.
Say you slowly ramp up an dimmer from one to 10
1-2-3-4-5-6-7-8-9-10
An incandescent will brighten like this:
1-2-3-4-5-6-7-8-9-10
An Led will brighten like this:
0-0-2-4-6-8-10-10-10-10
Which is completely unacceptable to me, although most people don’t have every light in the house on a soft-start electronic dimmer like I do.
This is actually a really, really tricky problem. The issue is the way conventional dimmers work. There are two types one which starts conducting part-way into the AC cycle, and the other (much less frequently used) which dims by cutting off the power after a certain percentage of the AC cycle has occurred. For an incandescent lamp, it really doesn’t care what the voltage across it looks like - it’s brightness is determined by the average power (the average of the instantaneous voltage * current). So, weird waveforms don’t bother it.
But, an LED driver not only needs to power the LED, it needs to power itself. So, it’s not an easy task being powered by a dimmer - it has to be able to operate close to zero volts, and still power the LEDs (which, if you read my earlier post, require a certain minimum voltage to light up at all). There are ICs that are designed to do this, but they require a fair amount of support circuitry, and so the cheese-ball foreign LED lamp manufacturers just punt, and don’t support dimming.
You can, it just takes a little more complexity to implement. Human eye (and brain processing) response is not linear, so a 50% drop in intensity isn’t perceived as “50% less bright” to a user. The eye has amazing adaptive range, especially at the low-light end, so I would opt for making a “smart” light that has a processor that can apply a scaling function to the LEDs. When I propose this to the boss/customer, their response isn’t “My, how elegantly clever my dear Gargoyle, have some brandy.” It is instead “It costs what?!?!?”
So to your example:
What human sees as an even ramp:
1-2-3-4-5-6-7-8-9-10
What the LEDs are actually emitting to fool your eye:
.001-.002-.004-.01-.02-.1-.5-1-5-10
It’s pretty easy to switch at kHz, but for some reason some designers are lazy and end up with flickery crap.
There’s another problem, though. Incandescents decrease their color temperature as they dim (this is obvious, in a sense). So there’s an expectation of this for other lamps, especially since dimmers are often used to “set the mood” and simulate candlelight. LEDs just decrease in brightness, though, without any shift in color. Ideally, LEDs would have a red chip in them that increases in intensity relative to the rest of the light as the lamp dims.
Yes, good point, I’ve done those before also. It’s orders of magnitude more tricky when you get into color curves and LED tolerances. IMO, at the end of the day the industry is best finding new standards for LED lighting instead of trying to mimic pure incandescent behavior as the “best” target point for everything. For example, it is common to “dope” your white LED array with some yellows or reds to give a more incandescent appearance.
Example: If you are doing print copy for a graphic artist, you sure wouldn’t want your color temperature to shift as you dim your incandescent lights and throw your perfectly color-balanced palette out of whack would you? Wouldn’t you love an LED light that held it’s color temp across any brightness level so your print copy is always accurate?
So I bought half a dozen 60 watt 2700k Crees at HD today.
First, they come in a two-piece plastic shell surrounded by a piece of cardboard.
When I opened the first one, it felt funny. The back of the bulb had shattered, but it maintained its shape because of the gummy coating. So, examine all sides of the bulb carefully at the store. All the rest were OK.
I put them into a couple of wall fixtures with a white translucent cover with open ends. I can’t tell a difference from the old incandescent bulbs. But it’s not a very demanding application and I don’t have any high-tech measuring devices.
We just bought a house, and our long-term project is to replace existing incandescents with LED bulbs as they burn out. We had exactly the same experience as you- one of them was broken, but we couldn’t tell until we opened the package.
Honestly, I’m really enjoying the LED bulbs. I can’t really tell the difference between them and the previous bulbs, except that they’re perhaps a bit “cooler” in color. What I’m really hating, actually, are the fluorescent tube lighting we’ve got in the office, garage, and the kitchen. The sooner we can get rid of those things, the better. Who ever thought they were a good idea? They’re loud, annoying to store, burn out a lot, their light seems to suck the soul right out of me, and I can easily see their flicker rate. And replacing *those *lights with something better is going to be a lot of work.