[Wayner]

Incandescent dimmers use triacs that shorten the half wave time cycle according to where the dimming control is set at. It is a very fast acting "on-off" switch that handles the 120 volt sine wave. The shorter the half cycle "on time" the more the incandescent lamp dims. Old fashioned dimmers used rheostats that were simply a great big resistor. Not very efficient, but the one from my church has been there for as long as I can remember. LED lamps will respond to this type of dimming, not the greatest, but you should be able to dim it say....25% of full power. I'm fairly sure that most LEDs sold at local big box stores will be able to use the incandescent dimmer to some degree without changing out the dimmer. Until the day comes when LED is the standard and incandescent is no more, which will still probably take a half a decade, the industry will have to assume the the consumer is going to buy an LED lamp and run it on his existing dimmer. That is the reality of it right there.

BTW, if you want to get into professional LED stuff, here is a job I finished last year (I designed the entire product, sheet metal and all), here is a photo of Mount Olympus High School. While the photo does look like a computer image, it is not. The LEDs are RGB, DMX controlled and can create over 2 million different shades of light color. The great big pain in the ass is that every controller has it's own DMX address and it and the driver can usually only handle about 6 meters of LED, so there are lots of drivers and lots of controllers and lots of control wires and lots of power wires going around in circles.






If I recall, there were 6 different size rings from 6 foot diameter to 24 foot. Yes, the 24 footer was made in 4 sections.....

 

[Wayner]

Here is another image of the lower floor:

[WGH]

I installed my low voltage LED under cabinet lighting using a Magnitude M20L12DC-AR : 20W 12VDC Magnetic Dimmable LED Driver specifically designed to be used with a low voltage dimmer.
http://www.magnitudeinc.com/products/m20l12dc-ar/

The transformer and a Lutron DVLV-600P-WH Single-Pole Magnetic Low Voltage Dimmer switch work perfectly together with no noise anywhere. Stereo has no background buzz no matter how low the LED's are set and there is no interference in the TV either.

I have very short runs so the 120v lines were turned into low voltage lines. All the parts were purchased through a commercial lighting supplier, they put together everything I needed so I didn't need to do much research. It's nice to deal with professionals.

Wayne

[Wayner]

Some professional LED controllers use a simple potentiometer (like 50k ohm) to control the dimming. However, in my experience, the pot may have a short life as it can get pretty hot.

Here is the problem for armature and professional alike: The LED industry is like a run-away train. Most folks use something like an Advance driver, but many have devised their own controllers and LED strips. It is kind of a circus to get any kind of a lighting project's loose ends bundled up. Many times I have gotten really sick and tired of it. They are pretty much all differently made and certainly vary in quality. A few of the big players actually produce some of the biggest garbage there is to work on, install and to get operating properly.

My advice to all is to stick with the LED self ballasted (or self driven) lamps and be done with it. I do see that Parts Express has some RGB on a reel that might be fun to play with, but remember that you need a driver (the power source) and a controller plus the string of lights.

[stereocilia]

A 22-item Specifications table and none of them are Color Temperature or Lumens?   

Steve

Ugh.  I know...It's Home Depot, so there's that.
It's on the box.  240 Lumens, 5.87 Watts, 41 Lumens per Watt, Color Accuracy 80, light color 2700

[stereocilia]

I actually liked the way the light looked.  I know that Home Depot is not the best place to find quality stuff, but the Home Depot hardware was already there.  I can just snap in the track heads without so much as finding a step stool.  I was going for cheap, easy, and effective.  Pick any two, right? 

Based on this thread alone you can probably think of as many "How many audiophiles does it take to screw in a light bulb" jokes as I can, but in all seriousness thanks for the education in lighting.

[ctviggen]

Personally, I wouldn't trust the color temperature on the box.  I have many different 2,700k LED lights, and some of them have great light, and others have light that makes everything grey (I assume this is caused by color temperature not being correct, but maybe it's color rendering index?).  Unfortunately, you really have to try the LED.  I've had good luck with CREE recessed lights and Philips LED bulbs, but I don't like the CREE bulbs I have, nor do I like the cheap candelabra bulbs from Costco (both the latter make everything grey). 

On the other hand, the amount of energy saved is amazing.  The recessed lights dropped the power output from 65w to less than 10w, and these included the trim.  Only time will tell if the LED lights achieve their rated lifetimes. 

[Wayner]

There is also something called "color rendition index" or CRI. As you might guess, the light from the LED can appear to be 2700°K, but its CRI may make things look a color shade or 2 off, either being like a blood red, rather then a lighter red. You have to ask yourself what color is daylight, and the correct answer is what is the sun angle. Colors look different in the morning to noon to the afternoon to twilight, but the sun may have the same color appearance. I'm sorry to get into this aspect, but this is the answer. Now if the LED manufacturer isn't going to publish the Kelvin temperature, I doubt he is going to publish the CRI. If the LED doesn't do what you want, ask before you buy if you can bring it back.

There is lots of differences in bulb styles too. A par 30 has a long neck and a short neck version, for example. A long neck version might stick out of your recessed fixture, by lots. For mine, I needed the short neck version. BTW, when you see a lamp spec that says like the par 30, the 30 is the lamp diameter, which is 30 X .125" or 3.75" in diameter. A T8 fluorescent would be 8 X .125 or 1" in diameter and so on....

Wayner