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Answer by andygroch
That is quite a challenge. I believe that most any light you put there is going to have an issue with all the heat from the fireplace. Mr16′s and GU10′s come in line voltage so there would be no transformer needed. Probably the ideal option would be a small track section with a fixture that would handle a PAR16 type bulb. These bulbs are availible in a capsylite, which is nearly all ceramic except for the base and are designed to withstand a lot of heat. That would be about the ideal option I could think of for your aplication without making some sort of heat shield. Even if you did that you are containing the heat that the fixture would put out which is not a good thing. I hope that helps you. Check with your local quality lighting showroom for any further assistance. That is what we are here for.

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Add your own answer in the comments!

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Answer by starryskyn
http://en.wikipedia.org/wiki/Lux
One lux is equal to one lumen per square metre, where 4π lumens is the total luminous flux of a light source of one candela of luminous intensity:
1 lx = 1 lm·m-2 = 1 cd·sr·m–2.
As with other SI units, SI prefixes can be used, for example a kilolux (klx) is 1,000 lux.

The lux is one lumen/metre2, and the corresponding radiometric unit, which measures irradiance, is the watt/metre2. There is no single conversion factor between lux and watt/metre2; there is a different conversion factor for each wavelength, and it is not possible to make a conversion unless one knows the spectral composition of the light.

The peak of the luminosity function is at 555 nm (green); the eye is more sensitive to light of this wavelength than any other. For monochromatic light of this wavelength, the irradiance needed to make one lux is minimum, at 1.464 mW/m2. That is, one obtains 683.002 lux per W/m2 (or lumens per watt) at this wavelength. Other wavelengths of visible light produce fewer lumens per watt. The luminosity function falls to zero for wavelengths outside the visible spectrum.

For a light source with blended wavelengths, the number of lumens per watt can be calculated by means of the luminosity function. In order to appear reasonably “white,” a light source can’t consist solely of the green light to which the eye is most sensitive, but must include a generous mixture of red and blue wavelengths to which it is much less sensitive.

This means that white (or whitish) light sources produce far fewer lumens per watt than the theoretical maximum of 683 lumens per watt. The ratio between the actual number of lumens per watt and the theoretical maximum is expressed as a percentage known as the luminous efficiency. For example, a typical incandescent light bulb has a luminous efficiency of only about 2%
end quote

So bulbs you mention are 638x.02=12.7 lumens/W
then the 100W bulb is about 127 lumens and 127 Lux if it illuminates 1 square meter.
For other types of sources, with spectrum differences, a comparison is a crapshoot.

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Give your own answer to this question below!

The other day, I was at Home Depot and they had 12V, 50W halogen floodlights (MR16) on sale for just $ 0.67. So I purchased 2 to use with my dimmer. And the dimmer works great with it. The bulb dims and brightens. I hear a high-pitched whine as I adjust the dimmer from dim to very bright.

At first, I thought it was coming from the bulb. But it’s really coming from the dimmer. The battery powering the bulb is a 12V, 1.3AH battery pack (Ten 1.2V, 1300ma Nimh batteries). And if I bypass the dimmer and just hook up the battery to the bulb, it’s super bright and no whinning sound.

The dimmer doesn’t make a sound with anything else it’s connected to. So if I hook the battery and dimmer to a 21 LED MR16 bulb, no whinning or problem. Same with connecting LED strip lights. It’s just that 50W halogen that is causing the dimmer to whine.

Because the halogen is the most powerful light I am using, the only thing I can think of that is causing the whinning is the dimmer switch is not able to handle the roughly 4A current the bulb is drawing. But that would be 1/2 the 8A rating of the dimmer and I doubt it’s that bad.

Any help you can offer me would be appreciated!
FYI, it’s the halogen bulb that is making the whinning, not the dimmer!

I’ve heard that AC dimmers can have trouble with clean waveforms, causing whinning. Is it possible the same thing is happening here with DC?

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Answer by Tim C
Because the halogen is the most powerful light I am using, the only thing I can think of that is causing the whining is the dimmer switch is not able to handle the roughly 4A current the bulb is drawing.
That is correct.

But that would be 1/2 the 8A rating of the dimmer and I doubt it’s that bad.
Whining does not mean it is bad. It whines because it dims by very swiftly turning the power on and off.

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Add your own answer in the comments!

The basic specs of the lamps are as follows:

12v
MR16 fitting
Dimmable
White (ish) light

The problem is, I am a bit confused with how to incorpoate a mains voltage to 12v transformer into the circuitry. I am also confused with the term ‘Trailing edge dimmer’, which seems to be something I need if I am to use a dimmable LED bulb.

Can anyone help me? I need some directions as to what to do.

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Answer by wires
You need to run the mains to the transformer and then do everything with the 12 volts. Rectify and filter the 12 VAC to a decent 12 VDC. You probably cannot use a trailing edge dimmer as these operate on AC and LEDs operate on DC. It would not make any difference if you used a trailing edge or leading edge dimmer, you will not get the results you want. LEDs also do not respond well to voltage dimming. The light output varies very tiny with a fairly massive voltage reduction. You should look into PWM (pulse width modulation) for controlling the light output from an LED. This works by simply pulsing the voltage through the LED very fast. When the LED is off for about half the time that it’s on it appears dimmer. For more information on dimming LEDs check the links below.

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What do you think? Answer below!

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Answer by Goodspeed
if the led do not draw enough power then the lights would not be light enough and still will turn on ,if you want to replace the MR16 with leds,and non-dimming factor, this can be done ,you do not have to afford the dimmer ,you can log on www.ledlightsworld.com there would some pro. stuff you are looking for ,thanks

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Know better? Leave your own answer in the comments!

The other day, I was at Home Depot and they had 12V, 50W halogen floodlights (MR16) on sale for just $ 0.67. So I purchased 2 to use with my dimmer. And the dimmer works great with it. The bulb dims and brightens. I hear a high-pitched whine as I adjust the dimmer from dim to very bright.

At first, I thought it was coming from the bulb. But it’s really coming from the dimmer. The battery powering the bulb is a 12V, 1.3AH battery pack (Ten 1.2V, 1300ma Nimh batteries). And if I bypass the dimmer and just hook up the battery to the bulb, it’s super bright and no whinning sound.

The dimmer doesn’t make a sound with anything else it’s connected to. So if I hook the battery and dimmer to a 21 LED MR16 bulb, no whinning or problem. Same with connecting LED strip lights. It’s just that 50W halogen that is causing the dimmer to whine.

Because the halogen is the most powerful light I am using, the only thing I can think of that is causing the whinning is the dimmer switch is not able to handle the roughly 4A current the bulb is drawing. But that would be 1/2 the 8A rating of the dimmer and I doubt it’s that bad.

Any help you can offer me would be appreciated!
FYI, it’s the halogen bulb that is making the whinning, not the dimmer!

I’ve heard that AC dimmers can have trouble with clean waveforms, causing whinning. Is it possible the same thing is happening here with DC?

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Answer by Tim C
Because the halogen is the most powerful light I am using, the only thing I can think of that is causing the whining is the dimmer switch is not able to handle the roughly 4A current the bulb is drawing.
That is correct.

But that would be 1/2 the 8A rating of the dimmer and I doubt it’s that bad.
Whining does not mean it is bad. It whines because it dims by very swiftly turning the power on and off.

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Give your own answer to this question below!

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Answer by andygroch
That is quite a challenge. I believe that most any light you put there is going to have an issue with all the heat from the fireplace. Mr16′s and GU10′s come in line voltage so there would be no transformer needed. Probably the ideal option would be a small track section with a fixture that would handle a PAR16 type bulb. These bulbs are availible in a capsylite, which is nearly all ceramic except for the base and are designed to withstand a lot of heat. That would be about the ideal option I could think of for your aplication without making some sort of heat shield. Even if you did that you are containing the heat that the fixture would put out which is not a good thing. I hope that helps you. Check with your local quality lighting showroom for any further assistance. That is what we are here for.

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Know better? Leave your own answer in the comments!

Thanks!
Hi, the individual LEDs are not 12V but the MR16 bulb (each containing 3 LED chips) is rated for 12V AC or DC. It has, as I mentioned, it’s own voltage regulator built in. The spots work well with one or two halogen lamps or just one LED (either one, so they both work fine). When both are connected then all blinks briefly and goes black.

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Answer by billrussell42
What does “12 volt LED” mean? LEDs operate at voltages around 2.8 to 4 volts, not 12 volts.

If it means the LEDs have a resistor built in, so they operate from 12 volts, then you should be fine, and the transformer should not shut down, as the current would be a low lower than the halogen lamps drew.

So I suspect these are NOT 12 volt LEDs, and they need a series resistor which is missing, so the current is much higher than it should be. Probably means the LEDs are cooked already.

Another possibility is that the 12 volts for the halogens is AC, not DC, and the LEDs require DC.

So you need to look at the specs on the LEDs, and also check the 12 volt supply. I suspect it is AC.

.

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What do you think? Answer below!

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Answer by zawalis
First of all, DAMN, someone took you for a ride. You can run MANY lights off one transformer…I have no idea why you have so many. Hella Lighting makes nice, flush mount fixtures that are bedded in epoxy, I have installed them in a sailboat and have 19 on ONE circuit. LEDs put out a different temperature light though, be careful that you are okay with the change to the lighting.

Your energy costs should drop to near zero compared with what you are using now.

Each fixture contains four LEDs and consumes 0.5 watts. With 17, you are speaking about under 10 watts total. Frankly, the cheapest source of high quality DC power in that range is a personal laptop power supply. See eBay and ensure that they have CE and other ratings.

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Know better? Leave your own answer in the comments!

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Answer by Goodspeed
if the led do not draw enough power then the lights would not be light enough and still will turn on ,if you want to replace the MR16 with leds,and non-dimming factor, this can be done ,you do not have to afford the dimmer ,you can log on www.ledlightsworld.com there would some pro. stuff you are looking for ,thanks

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Know better? Leave your own answer in the comments!