LED lighting ?

m

Ah, but does the little man inside the refrigerator leave that light on when the door's closed? The ancient riddle rises yet again...

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Cheers, 
James Arthur

On a sunny day (Thu, 7 Mar 2013 16:09:53 +0000 (UTC)) it happened Frank Miles wrote in :

Of course the fridge light is normally only on when you have an open fridge door, so seems you are one of those green fanatics..

Hint: guess you checked if it was on all the time by looking in the fridge.

Energy is cheap, there is oil everywhere.

The light is only on when the door is open, which does a lot more to raise the interior temperature. 40 W for thirty seconds or less does't generate much heat.

I've bought strips like this at the flea market and hamfests for similar prices.

Note that the radiation angle of a screw in LED bulb is about 300 degrees, while the stripping is typically 120 or 180 degrees. That's roughly twice as much light going to lighting the area of interest, reather than illuminating the ceiling or other wasted areas.

As for cost comparison, the screw in LED bulbs cost between 25 and 50 lumens per dollar. Using this example of LED strip lighting: that is $170 for a 16.5 ft strip, that produces about 310 lumens per foot or a total of 5100 lumens or: 5100 lumens / $170 = 30 lumens per dollar In terms of light output, I would say they're about the same cost.

By necessity, halogen bulbs need to run hot. This limits their application to easily cooled fixtures.

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Jeff Liebermann     jeffl@cruzio.com 
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ot

But in lumen-hours per dollar, LEDs shine.

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Cheers, 
James Arthur

Michael A. Terrell schrieb:

Hello,

but how do you feel if there is to much CO2 in the air? You may get some headaches.

Bye

You exhale about 4% CO2, 40,000 PPM, so just sitting around in still air, or sleeping under a blanket, increases the ambient CO2 level way above natural levels.

Always sleep alone to minimize CO2 in your bedroom. Never cook with a gas stove or oven. Avoid campfires, candles, and enclosed spaces, like tents, cars, or bathrooms.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators

Why it feels like the sky is falling. What else?

Bye bye.

Door opening isn't as huge as I thought. With the simplifying assumption of a constant exchange rate of 2L/sec and a 20degC temperature difference- that's about 50W. So the LED lights reduce the thermal loss by nearly half (our frig had 2 25W bulbs). When you have a younger person in your household who has to check the frig frequently in the chance that something even more palatable has arrived while his back was turned, it seems worth the low cost of the lower-power LED lights.

Unless you have a silly kind of fridge*, the lamp is only on when the door is open and all kinds of warm air is entering the space (as cold air falls out the front). Even if the power consumption is equivalent to double, it should not be on for more than a few minutes a day.

I put an LED bulb in the clothes dryer- I was a little worried it would die during the first cycle, but it seems to be surviving just fine. Only a few watts incandescent equivalent.

• With high efficiency lighting I suppose it would be practical to have the lights on in the fridge all the time (with a see-through door, of course).

Yes, and most of the off the shelf stuff has really mediocre thermal design, running the LEDs at 100% of absolute maximum rating, which reduces efficiency and really kills longevity. I was thinking making something with a large area would help dissipate heat.

Jon

the back, and it probably runs at close to 100C.

Jon

Right, I agree. The prices of the LEDs are ALL OVER the place, from $0.45 in small quantity to over $7 each!

I'm looking to try replacing fluorescent ceiling fixtures, so a planar array would be quite fine, and the larger it is, the less it acts like a blinding point source. I've found some that can run conservatively at 1 W per unit, so 10 in series would pull 10 W and produce 1000 - 1200 lumens.

That is 64 lm/W, the ones I'm looking at are about 104 lm/W (not counting conversion from line power).

No, 100 lm/W is definitely better than T12 fluorescents, but maybe not better than the new T8. But, it would require major retrofitting, anyway, to go to T8 ballasts, and would be almost immediately obsolete.

Jon

The ones I'm looking at have a max current of 1 A, "rating current" of

350 mA, and they have a data sheet claiming 65000 hours to 95-98% of original light output at the 350 mA current.

Jon

The advantage of LEDs in the 'fridge is that more of them can be spread around to give more even lighting. When Jr. is rummaging around, perhaps he won't leave the door open as long if he can see his kill faster. Maybe he won't reopen the door to check if something was hiding in the shadows, escaping the last hunt.

You are truely ignorant.

How will you protect them from condesation?

The Publix supermarkets around here have motion sensors on their glass doored coolers & freezers so the lights only come on when you're about four to six feet away.

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

Hey, it's only 6W. 500lm (if true (and probably not)) would be 83lm/ W. The ones I see in Home Depot are 45-50lm/W.

I picked one with a big heatsink because it'll run cooler than the ones without. They've got lots of choices. Too many.

YMMV.

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Cheers, 
James Arthur