LED lighting ?

"Nico Coesel"

** "probably" ???

Wot bullshit is that ?

ROTFL

Jr. is not the problem. Try a son-in-law (lawyer natch) who'll scarf shepherd's pie from the fridge and eat it _cold_, with mustard yet :-( ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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I love to cook with wine.     Sometimes I even put it in the food.

No point in that. Put a pushbutton on the outside that lights them up for a minute or two at most (or longer if the door is open). However, a see-through door will cost you a great deal of energy, and the storage on the door. Easy to find commercial models with clear glass doors, but they won't be particularly efficient, from what I have seen.

If you want fridge efficiency, the light is the least of it. Putting an over-ride thermostat on an efficient chest freezer, so the cold air stays inside when you open the door does much more. Becoming more common among people that really need to save power (a normal mass-market AC chest freezer and the extra solar panels to run it and its inverter losses have largely blown the cost of a "super-special-DC-solar fridge" out of the water), but still not particularly popular otherwise, except among brewers. And, perhaps, some engineers.

Oddly, even the super-special-super-insulated DC solar fridges are still stuck on the upright fridge model, for the most part. And virtually all modern fridges put the compressor in the wrong spot - the hot thing goes on top of the cold things, not under them. The very old ones usually got that part right.

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Cats, coffee, chocolate...vices to live by 
Please don't feed the trolls. Killfile and ignore them so they will go away.

Might be a problem in a more humid climate, or in the freezer. So far I haven't seen any in this standard "frost-free" unit.

Well, I, for one, am not going to bend over for the environmentalists.

I like stuff on the shelves where I can reach it easily.

Maybe they could do an on-demand air curtain thing on the front or something. A good fridge costs $thousands... you'd think they could make some improvements.

Best regards, Spehro Pefhany

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You're an idiot. A complete and utter, presumptuous in all the wrong ways, TOTAL RETARD

There are hanging-strip air-retention gadgets for consumer fridges-- that would help.

Or, just could fill empty spaces with inflated plastic bags. That keeps the cold air from falling out, and warm air from rushing in. Easy, cheap.

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Cheers, 
James Arthur

** Pretty neat debating cheat really - when you have no facts to support your case, invent some and see if your opponent is dumb enough to try to disprove them.

This cheat goes one better, by alluding to non existent facts that can never be disproved.

Bit like the " silent majority " argument.

Nixon's one, not Aristotle.

.... Phil

Nixon was right about it at the time, however. Did you live over here in the '70s?

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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** Nixon was alluding to folk who did not speak up publicly, but allegedly supported has views - while Aristotle used the phrase to allude to the dead. ** Nice red herring fallacy.

... Phil

Yes, LED lighting cost is coming down. A 6 watt LED lamp replacing a

25 watt incandescent pays for itself in 3 years if used 3 hours a day. I found a single 1/2 inch diameter 9 watt LED with nine 1 watt LEDs in a 3X3 matrix awhile back on ebay. I run it at 5 watts on a big heat sink to keep it cool. But the light is still not as pleasing as the old incandecents , so I still use my 60 watt incandescent desk lamp.

-Bill

I simply do not believe that, unless they have invented a completely new fluorescent material for converting blue radiation to red/yellow radiation. All currently known materials degrade quite fast in very intense radiation.

"LUXEON Rebel ES is tested and binned at 700 mA, with current pulse duration of 20 ms. All characteristic charts where the thermal pad is kept at constant temperature (25ºC typically) are measured with current pulse duration of 20 ms. Under these conditions, junction temperature and thermal pad temperature are the same."

Even that is completely useless data. Thermal pad temperature at 25 C? Are they serious ? Swimming unprotected in a fish tank ?

At least CREE has a lot of documentation of various parameters vs. junction temperature and vs. forward current including light output drop. They now specify most parameters at Tj=85 C, a value much closer to real operation conditions. Most manufacturers still specify characteristics at Tj=25 C i.e. at a beginning of a pulse.

While it is possible to calculate real operational values based on characteristics at Tj=25 with characteristics charts, it requires a few repetitive steps. First calculate forward voltage at current Tj, then calculate power dissipation and with the thermal resistance, calculate new junction temperature. Repeat the previous calculations based on the calculated junction temperature and hope that the repeated calculations will converge.

For more accurate calculations, one should consider that all power input to the device is not converted to heat, but some power even escapes as visible light :-), thus reducing temperature rise. However, the conversion efficiency varies with temperature as well as forward current.

To calculate the characteristics from a constant voltage source and series resistor still requires more iterations due to forward voltage changes vs. junction temperature and current.

I'm not convinced that chest would be worse. With my current standard upright I have to bend/crouch way down to get at stuff in the back/bottom, and stuff is hard to see/access in the top back (especially) and any back of the shelf (generally.) Reaching down into a chest is actually easier for me. I'll be trying it out, anyway, and if it doesn't fly it can go back to being a freezer.

I did see a cute model in a 1950's era book, where the fridge was a

3-door ceiling-hung kitchen cabinet, so everything would be pretty much at eye level and no bending, but I've never seen one of those outside of a book. It might even have been double-sided (6 doors, grab from either side, the back of the shelf on this side is the front on the other - hang over an island countertop.) Unless something like that is being produced and I haven't found it, I think you'd have to custom build it from commercial components, which would be kilobucks. If mass produced it could be done for mere hundreds. I suspect inertia killed it - we are still basically stuck with refrigerators that would fit in the footprint of an icebox, because that's what the hole in the kitchen looks like. A more sensible approach like this would require designing the kitchen to take it, rather than dumping a box into the hole that was left for the icebox, even if the house is newer than iceboxes.

And then there's the ultimate solution - friends with an old house have a walk-in and reach-in refrigerator that takes up one whole wall of the kitchen, and it has icebox-style doors of various sizes on the kitchen wall (it may well be old enough that it was a huge icebox to start with, and only became a refrigerator later.) Frequently-accessed small stuff goes behind a small door. Small farmers (particularly) have figured out ways to build efficient walk-ins at a reasonable cost by messing with the controls of air conditioners (mass-market and subject to efficiency programs) rather than commercial units (small market and not as subject to efficiency programs - many times the cost.) I suppose I should look at that as an approach to the cabinet fridge that might cost less than kilobucks.

--
Cats, coffee, chocolate...vices to live by 
Please don't feed the trolls. Killfile and ignore them so they will go away.

On 8/3/2013 4:22 PM, snipped-for-privacy@downunder.com wrote: ...snip...

I too would be really interested in some independent data on the life-time of the current phosphors. The often-claimed 50,000 hours seems a bit too good to be true.

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Regards, 

Adrian Jansen           adrianjansen at internode dot on dot net 
Note reply address is invalid, convert address above to machine form.

Some more or less reliable data for one manufacturer at

Note for instance the 6000 hour measurements for XR-E LED, which has a

1000 mA maximum current. Various tests from 25 C case temperature and 350 mA to 85 C at 1000 mA are shown with nearly three times faster drop in the last case.

Some info about calculating L70 and L85 lifetimes based on those 6000 hr luminance maintenance figures can be found from

As can be seen, selecting the current and temperature cause large changes in the expected L70 lifetime figures. Marketing people then select the best figures, even if the parameters are not valid in the same case :-).

..>Yeah, just 450 lumens, not real impressive.  Check the huge heat sink on

That's kind of you--your LEDs will thank you for it. I wonder about the LED strips mentioned up-thread--I'd think they'd get mighty hot. There doesn't seem to be enough copper. Cool LEDs last oodles longer and are more efficient too.

I still like halogens for color, but mostly CFLs and my favorite flashlight for lighting.

I'm suspicious of the blue LEDs behind that yellow phosphor--blue isn't good for corneas, lenses, or retinas. But, I'll probably give 'em a whirl. Meanwhile, CFLs last me forever, so it could be a while.

--
Cheers, 
James Arthur

Well, one of you has to be wrong ;-) (I've used the LEDs. From my limited sampling, I suspect they're telling the truth. If not, it'd be quite a scandal.)

The thermal spec is a bit rosy, prolly for lm/W bragging rights, but they give enough curves and such that you can figure the actual efficiency and output under *real* conditions. (And yes, fish love it.)

--
Cheers, 
James Arthur

What about the 'phosphor' layer to produce white light? The die itself?

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Failure does not prove something is impossible, failure simply 
indicates you are not using the right tools... 
nico@nctdevpuntnl (punt=.) 
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