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Joined: Aug 2002
Posts: 402
jdevlin Offline OP
We are considering trying some of these but when looking at the specs the light output looks way low - 55 lm compared to 1750 cd. My research indicates that 1 lumen = 1 cd.
Has anyone tried them? What do you think?

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Joined: Dec 2001
Posts: 444
We have several customers who have expressed interest in these. Our first foray with a china company was disastrous, RUN, do not walk, RUN if any lighting supplier starts carrying these bulbs....

This example absolutely made less light then a standard MR16 but still produced a reasonable amount of light. More importantly, they look great and only consume 3 watts. HOWEVER, what we soon found out, they either, overheat, burn out, or dim after a week of use. They are expensive as well. We are still in negotiations with the supplier for a replacement bulb.

We will be using (fingers crossed) the new LED bulb from Standard lighting products. I've had good sucess with their products and will be test running a few of their bulbs, before jumping in.

Lesson learned guys, just be careful with the new tech stuff till it gets proven.


Last edited by Sandro; 04/15/08 05:52 PM.
Joined: Aug 2002
Posts: 402
jdevlin Offline OP
My normal supplier doesn't carry any yet. Says they haven't been proved yet or don't give enough light output.
I have found another supplier that carries a brand called VaOpto.
Didn't mention in first post but the current units are on dimmers so they need to be dimmable. Are LED bulbs dimmable?

Joined: Dec 2005
Posts: 872
Likes: 4
You see a lot of these on Ebay France (Ampoule LED) and Ebay Germany (LED lamp).

I don't know how good these lamps are. It looks that undersized resistors are used, or cheap SMPS are used to supply the LED's with.

I made a couple of Blue Green LED night light lamps in my house, hall, garage which are handy to find your way around in the dark.
Just used an old discarded base from a compact fluro lamp. 4 x 1 watt 8.2 kOhm resistors, 1N4007 diode to limit the current flow through the LED's to about 12 mA's. 9 or 17 LED's of choice et voila !

No burn outs and have these going now for about the last year.
Will put a photo on the electrical galleria

Cheers, Raymond

The product of rotation, excitation and flux produces electricty.
Joined: Jun 2006
Posts: 613
I bought a couple or MR16 lamps to use on my Bicycle. Enough light but too diffuse for riding fast. I bought an HID light system for the bike. I have these two mr16 lamps so I thought I'd install them in a couple of mostly decorative fixtures in my living room. I put them in and they just pulsed and went out. Dang I was sure i fried them. I thought DC lights on an AC electronic ballast. So I take the lamps back out and down to the garage to find out whether they were toast. Connected them to a 12 volt battery and they light up fine. I next tried a class 2 transformer and they worked on AC. What is going on I think? I then dug out a couple of low voltage lighting ballast and they won't light. The ballasts work on incandescent lamps but not LEDs. After a couple of conversations with various suppliers I discover these ballasts won't work with LED as the current draw is too small for the ballast to work.
A simple magnetic trasformer works or a special electronic ballast for LED bulbs would work. I don't know of a magnetic solution that would fit in the fixture so I need a ballast and the local suppliers want like $60 each. If I do the math it comes to nearly $100 per fixture to install LED lamps. At $0.06 per KWH i figure I can save enough electricity to pay for the Upgrade in like 100 years. I would pay $10 - $20 for a ballast so if someone knows of a LED specific low voltage ballast for that kind on coin let me know. I would be happy to have a place to use these lamps and these fixtures would work with the color of the Leds too. Dimmable would be a bonus too.

Joined: Jul 2004
Posts: 9,959
Likes: 34
I wonder how big a resistor you need to hang on that ballast to load it? It is eating into your savings tho. You may be able to reverse bias a diode in series with the resistor so it only conducts on the down stroke when the LEDs are off. Maybe just wire half the LEDs reverse polarity.

Greg Fretwell
Joined: Jun 2007
Posts: 14
These are coming along, but really no good for replacing flood lights at all, and so far only good for very low wattage spots. the 5 wattt and triple 3 watt ones put out enough light that they can be actually useful, but are not as bright as the real bulbs. You cannot convert a candle to a lumen that easily so it's not that straightforward, but they are definitely dimmer.

The other problem with these bulbs is that the brightest ones come in very cool white colors. Like 6000k color temperature. Which is fine for the high bay lights in the loading dock, but nobody wants that in a 30 watt reading lamp. Many do also come in warm white colors that are more like the bulbs they are replacing, but you'll have to experiment to see what you like best.

The problem with LED's is that you cannot run them in a setup like this with just a resister ballast. As the LED's heat up their resistance goes down, allowing more current to flow making them hotter and still lowering their resistance. If you're running them close to the edge you can actually get to a runaway condition that ends in their bonding wires melting. So they have to have a current limited power supply inside, and very good heat sinking. As we know from CFL bulbs, cheap power supplies burn out quickly.

There are dimmable ones just reaching something like a sane price point right now, in another year I expect them to be about ready to put in, but right now the good ones are too expensive and the cheap ones are just garbage.

Additionally, since all of the light is focused, they dont look nice in decorative fixtures at all. I have some MR16 bulbs in my front hall shining on some pictures that I'd love to replace with LED's, but the fixtures are frosted glass which glow nicely from the wasted light from a regular bulb, with an LED in there they would just be dark, illuminating only the picture and not the hallway unless I point one there.

Joined: Aug 2002
Posts: 402
jdevlin Offline OP
The fixtures have a transformer in them. I just changed one. We are not going use for the time being. This would be in the executive area of the office outside the presidents office. I don't want ony strange things in that area.

Thanks for all the input.

Joined: Sep 2003
Posts: 650
Originally Posted by jdevlin
My research indicates that 1 lumen = 1 cd.

To help with your future evaluation of these numbers:

a lumen is a measure of _total_ light flux, a candela is a measure of light _intensity_ in a particular direction.

If you look at a light source from different directions, it will appear brighter or dimmer depending upon its directional characteristics. The brightest point gives you the cd measurement.

Note that a very well focused light source could have a very high cd measurement, even if it doesn't put out much total light.

You can make an analogy to linear measurements. Light flux is to light intensity as volume is to height. Consider a mountain.

The peak of the mountain is so many meters high. The volume of the mountain is so many cubic meters. You can have a 'mountain' that is short but very wide, having a large volume, or one that is very tall but quite narrow, having less volume.

The exact relationship is that 1 cd is a light intensity that results in 1 lumen per steradian. To go back to the linear measure analogy, this is like saying that 1 meter is the height that produces a volume of 1 cubic meter per square meter. There are about 12.6 steradians in a sphere, so a perfectly even 1 cd source would put out about 12.6 lumen.


Last edited by winnie; 04/24/08 02:18 PM. Reason: adding specific values

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