[Svartalf]

Originally posted by tw
About 1975, a Lockheed Jumbo L-1011 circled Miami with no 'front landing wheel locked' indication. So busy were the cockpit crew that a slow decent crashed into the Everglades. The landing gear was OK; just a burned out 327(?) light bulb. 300+ lives lost for the want of a light bulb.

Tragic, isn't it?

However, by the mid 1960s, Red LEDs had already been developed. At about $100+ per bulb, all cockpit indicator lamps were replaced with plug-in LED equivalents. Of course America had enterd a 'we fear to innovate' period. By 1984, in another job of fixing failed designs, I replaced all indicator lamps with LED equivalants at about $6 per bulb. But even in the 1990s, people still replaced incandescent indictor bulbs. Why?

Combination of expense and efficiency as you've pointed out. Don't blame it on lack of innovation- blame it on pure unrestrained greed.

In 1975, LED's were moderately expensive things and needed some extra circuitry (that wasn't small) to drive them to usable brightnesses as indicators. Combine this with a philosophy of, "that's $20 and this bulb over here is only $.50 and lasts quite a while- we'll use that..." because managers and businessmen are worrying about bottom lines. That's not to say that they shouldn't be worrying about that- it's just that many of our tragedies (The Challenger shuttle catastrophe is offered as another example, here...) occur because of worrying too much about "the bottom line".

Replacing them with somewhat costly, but dramatically more efficient LEDs at the time you did made sense. And I think you'll find that many modern planes, etc. use the LEDs in just about everything now- they're cheap and last "forever".

Semiconductors operate on 'holes' and 'charges'. Holes are atoms missing an electron. Charges are atoms with an extra electron in their shell. When a hole combines with a charge, then light is emitted. This is how advanced digital semiconductor manufacturers can debug complex digital circuits. Infared light is emitted when the transistor turns on. It is also how LEDs and their cousins, semicondutor lasers, operate.

Nice layperson description there.

One problem is that if holes and charges combine inside the semiconductor, then the light does not escape. Only 10% would escape. Hewlett Packard recently demonstrated a phenomenal 55% efficiency. IOW there is plenty of room for innovation and the west coast attitude of advancing mankind appears to be alive and healthy.

Seems to be the same way with the southwest. The people in Austin, Dallas, and Sillicon Valley are striving for replacing all of regular light sources (not counting things like high-pressure sodium, etc.) with LED type sources. I suspect a breakthrough soon. They, along with the Japanese, Taiwanese, and Koreans are looking for that "holy grail" of lighting where all but the largest lighting tasks (extreme luminous levels, etc.) will be handled by LED type emitters of light.

Red LEDs achieved incandescent efficiency (18 lumens per watt) in 1990. Yellow and Green did same before 1995. White LEDs, which did not even exist in 1995, have already exceeded incandescent lamps.

Depends on the application. For replacing something like an indicator or a small flashlight, yes. For replacing something like a 40-75 watt incandescant or a 13-25 watt fluorescent- they're not quite there yet. You've got to count total lumens generated along with the actual efficiency.

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Halogen lamps, at about 25 lumens per watt, were surpassed by red, yellow, and green LEDs by late 1990. So why do so many traffic lights still require human service?
Eventually even MBA spread sheets will realize these advantages in innovation.

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Total cost of the units is the reason. They've dropped to the point where they're cheap and the efficiency is actually in excess of the tungsten lamp with minimal power loading. The RED units are the only types right now with the luminous output to be able to do this. The yellow and green units didn't quite make the cut year before last, but towards the middle of last year, they came up with units that will work well in this sort of application. Right now, all the cities in the DFW area are replacing the red tungsten lights with LED units as the tungsten units fail. The LED units are slowly showing and with new light installations they're going in first off.

Today, CA is doing anything to reduce electric waste and useless human labor. LED equivalents to incandescent bulbs only consume about 1/10th the power and don't require replacement service. Innovation marches on, especially in regions that chose to be innovative rather than cost control.

The people in charge are looking at short-term costs not long-term benefits. It will cost more to replace all of the lamps with LED units than the costs of the wasted power- and blackout/brownout problems weren't considered into that figure.

Long before Edision created his light bulb, experimenter were creating light from electricity in mid 1800s, using low pressure inert gases. Of course other innovations, such as electric generators, were necessary to make these flourescent lamps commercially feasible which is why Edison got so much credit. Edison's incandescent lamp has now been obsoleted by everything except cost controls. However the flourescent lamp still remains superior for interior lighting - 80 lumens per watt. Other superior technologies are Mercury Vapor and low pressure Sodium lighting (100 lumens per watt).

I do believe that businesses are already availing themselves of fluorescent lamps (which are low-pressure mercury vapor lamps...) and many consumers are too. Unfortunately, there's drawbacks that up until recently presented problems for health, etc. with the extensive use of fluoresent and other ionized gas lighting.

1) Fluoresent lamps generally flicker at 400hz. This can cause a beat frequency with some computer monitors that can induce headaches, etc. The 400hz. flicker can also do this by itself in some people.

2) Color. Until recently, most flouresent lamps were relatively pure white light (Definitely more "white" than sunlight, even...). Health-wise, you're better off (and less stressed) with light that is more "yellow"- more like the light that the sun gives off. Furthermore, while high-pressure sodium produces more yellow-orange light than anything else (which is also as bad as the "pure-white" light of the fluoresent lamp...).

3) It used to take a while for the lamp to "warm-up" and produce useful/pleasing light.

Recently, the makers of fluoresent lamps have been working the flicker, color, and start-up times. The light from a modern incandescent replacement is nearly identical to that of an incandesent in every way- except that it takes about 1/5 the electricity to produce it.

However, the cost of that sort of lighting hasn't gone down much- it can cost as much as 10-15 times what it costs to put a single incandesent into service to put a "replacement" fluoresent into service. Don't count long-term savings of the fluoresent into this reasoning- the people buying the incandesents are looking at the short-term, not the long-term.

For those not experienced in concepts of innovation, the continuing existance of incadescent lamps will be a perfect example of anti-innovation forces in today's society.

Anti-innovation or merely not thinking about alternatives for reasons of up-front costs of the alternatives? I'm inclined to think the second of the two there.

In Time Square are large outdoor displays such as the Nasdaq display that uses 18,677,760 LEDs. In 1960, the moving message TickerTape on the Allied Chemical building represented advance technology. Then America went into a 'we fear all innovation' mentality created mostly by concepts taught in business schools. Technology in Time Square was a big Sony TV. Today's innovation revival has stopped recessions, increased wealth, reduced poverty, created full employment, and rebuilt Time Square. Watch the LED and its future replacement. It may be the benchmark to measure innovation in America.

Actually, I don't think so as far as it being a benchmark... We've had innovation- but it's uses with regards to Times Square aren't a litmus test. The usages there and elsewhere lag behind the actual curve. They're just now coming up with bulb assemblies that do replace incandesents in lighting applications- interesting things.

How about a screw-in replacement for a 20 or 40 watt flood?
How about a "can" light that's used for architechtural and stage lighting that can be set to any of over 16 million colors.

These things will last for decades without needing replacement and operate instantly upon demand. The cost, however, for them right now is astronomical. It's something like $90-150 per bulb for the white-light LED lamp replacements and a 40w can will set you back $750-1000 dollars.

Long before they were major news stories, many in The Cellar had read of the Human Genone project, prions of Mad Cow Disease, a man name Milosevik, the hybrid electric car, etc. In this tradition, watch the LED.

Been watching it for years. The LED's about to take off- but it's just really in it's infancy proper right now.