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mrdon
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Gold
Re: Electroluminescence
mrdon   1/9/2013 9:55:45 PM
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Hi Cabe, Your right about the cost of adding a cap and the effect if it burst. Besides, a little flicker enhances the visual appeal. Emulates tiny candles with small flames.

Cabe Atwell
User Rank
Blogger
Re: Electroluminescence
Cabe Atwell   1/9/2013 6:24:51 PM
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mrdon,

I figured as much. I assumed I was seeing the 60hz flicker from the wall. I suppose it would be cheaper and last longer to not filter the signal. I imagine if the cap burst, the whole strand would be shot. Similar to the only series bulbs. One goes, the circuit is cut. I am sure a line conditioner is sold separate. In other words, a CAP in a box for $29.99.

C

craig58
User Rank
Iron
Re: How bright are these things
craig58   1/9/2013 6:08:05 PM
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The one link I have states 20cd/m^2.

A cd/m^2 is also known as a nit, which is also 1 lumen per meter squared per steridian. There are pi steridians in a hemisphere, which is the total solid angle of a lambertian flat surface source.

A typical power led is about 1 mm on a side, or 1e-6 meters squared, and in excess of 100 lumens at around 1 watt drive. This is 3e7 nits So one led with 1mm^2 area = 100 lumens (or more )

A reference I have says a candle flame is 0.01 cd/mm^2 which is 1E4 cd/m^2.

So this would suggest 20 cd/m^2  is much dimmer than a candle flame, and to get 100 lumens total even, the area would need to be more than a meter squared.

mrdon
User Rank
Gold
Re: Electroluminescence
mrdon   1/9/2013 5:46:13 PM
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Hi Cabe, The LED Christmas light flickering is caused by using a simple DC power supply rectifier circuit. If there is no output capacitor to filter the ripple, the LEDs respond by flickering.

Cabe Atwell
User Rank
Blogger
Re: Electroluminescence
Cabe Atwell   1/9/2013 3:25:46 PM
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Flickering lights of CFL bulbs are very annoying and cause sleepiness. They even can cause epilepsy events and migraines

 

Any new type of light source is welcome.

 

On another note, LED Christmas lights have this flicker that drives me crazy. Anyone else see it?

 

C

TommyH
User Rank
Silver
Re: How bright are these things
TommyH   1/9/2013 1:34:30 PM
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I guess the jig is up.  Everyone now knows that I am getting sort of long in the tooth. 

Ann R. Thryft
User Rank
Blogger
Re: How bright are these things
Ann R. Thryft   1/9/2013 12:38:44 PM
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TommyH, I think you meant candela, not candle power. The latter is considered an obsolete unit of measurement. Today, this is measured via luminance or luminous intensity. Wikipedia has a good article on luminance.

William K.
User Rank
Platinum
Plastic illumination devices?
William K.   1/9/2013 12:27:34 PM
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It looks like this may possibly be a breakthrough, or possibly not. I remeber the electro-luminescent panels and devices that we had in the 1960's and wonder if it is a new implemantation of that technology. Those devices did provide a nice grale-free light, but not that much of it. I have no ideas about the relative efficiency, or lumens per watt. But the devices were very long-lived. I think that they were sort of expensive, as well. I have a couple of the inverter packages that were used by Chrysler for the EL instrument panels back in 1965, I think. They put out a very spikey waveform with a peak of almost 200V. 

It would be interesting to find out about the performance of an actual prototype, as opposed to that of a single research sample device. That is the sort of information that would help to understand where this technology lies, on the development toward commercialization curve.

Ann R. Thryft
User Rank
Blogger
Re: Skepticism
Ann R. Thryft   1/9/2013 11:55:09 AM
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I'm betting the reason ARS Technica didn't get "performance numbers" is because they asked the wrong question. So far, AFAIK, this is a number of prototype devices, not a single actual bulb with wattage specs, which is what will be produced after commercialization efforts are completed. The details that are available can be found in the (free) journal article, which we provide a link to. They include varying luminance intensities.

Ann R. Thryft
User Rank
Blogger
Re: Electroluminescence
Ann R. Thryft   1/9/2013 11:54:15 AM
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There seems to be some confusion here regarding the difference between prototypes and working products, and the amount of time it requires to move from the first to the second. I made an earlier comment on this subject: "Maybe we're all used to Silicon Valley-style announcements of new technology for sale right now in high volumes, and not of the long R&D cycle behind that technology. In materials technology, especially energy-related, development can take a long time...The main researcher has had a single working device for a long time--but not a bulb, and, presumably, a very expensive device, and, I'd guess, one he's been tinkering with as a prototype."

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