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There's something off about LED bulbs

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Re: There's something off about LED bulbs

#701

Post by eimrine »

seszett wrote: post #696
eimrine wrote: post #425

Earlier quoted context omitted.

There is no such thing as a pure red LED. Those are blue ones but with light filters. If you don't see blue which is actually present and you see deep red which is actually absent then maybe consider yourself as brainwashed by marketologists.

I think you misunderstand the fundamental difference between "white" LEDs which are generally a blue LED associated with various phosphors that convert the monochromatic blue light into a mostly continuous spectrum going from blue to red, and the monochromatic R, G and B LEDs that each emit a fairly narrow band that is either red (with no blue or green at all) green (no blue or red) or blue (no red or green). Blue LE…

> infrared LEDs that emit at 940 nm

Is there any LED capable of emitting 780nm? Or maybe a luminophore for letting manufactures to convert invisible 940nm into anything visible? AFAIK both answers are negative.

Re: There's something off about LED bulbs

#703

Post by thuttinger »

leobg wrote: post #640
Self-Perfection wrote: post #581

Earlier quoted context omitted.

One guy bought over 4 thousands LED lamps over years, meticulously measured their actual specs and made a huge online catalog https://lamptest.ru/ I follow his project a bit and it looks like consumers are really at loss. Generally there is no reliable way to choose a good led lamp without consulting such catalog. Lamps packaging often lies about actual specs, lamps with the same packaging but manufactured in differe…

Great site. I wish he had an English translation. But I forgive him. This is what the Internet should be! Individual people who do one thing really well. So happy to see that this still exists online.

There is one guy that does the same for batteries, chargers, power supplies and more: https://lygte-info.dk/

Re: There's something off about LED bulbs

#704

Post by eth0up »

BizarroLand wrote: post #446
jghn wrote: post #278

Earlier quoted context omitted.

The big problem for me is, as a consumer, how do I know that brand X is producing quality bulbs that'll last a long time? I'm very happy to pay more for that. How does one sift through marketing to get to actual quality? And then how do I know that they stick with the high quality approach? What happens when a brand decides to rest on the laurels of their brand name and start slipping in lower quality parts?

I spent probably $150-$200 for 7 packages of "high CRI" "long lasting" phillips brand LED bulbs last year, for a total of 28 bulbs. 6 of them have failed in less than 9 months, either flickering so badly it could cause an epileptic seizure or just straight up dying on me. It's maddening.

I had similar issues with Phillips. I bought six over a year for the relatively excellent quality of the light, but they'd start flickering after a month or two. I had first suspected an electrical problem, but then tried them at entirely different locations in entirely different sockets and found the same. Haven't considered buying Phillips since and won't, ever. Nice light, shit construction.

Re: There's something off about LED bulbs

#705

Post by CydeWeys »

jasonlaramburu wrote: post #502
chongli wrote: post #465

Earlier quoted context omitted.

The big problem for me is, as a consumer, how do I know that brand X is producing quality bulbs that'll last a long time? The issue is that LED bulbs aren’t simple devices like incandescent bulbs. LED bulbs have an electronic power supply inside which drives the LEDs at a constant current. Power supply design is a major subfield of electronics engineering and there are all kinds of tradeoffs you can make to optimize…

>It is possible (and not very difficult) to design LED bulbs that will practically outlive their owners It is also possible (and not very difficult) to design incandescent bulbs that will outlive their owners. In fact, the first mass produced light bulbs generally lasted 2,500+ hours. In the 1920s, the major bulb manufacturers formed the 'Pheobus Cartel' in Geneva and secretly colluded to limit the lifespan of bulbs…

Ah yes, people, famous for living less than checks notes 2,500 hours.

Re: There's something off about LED bulbs

#706

Post by ridgeguy »

Maursault wrote: post #631
xxs wrote: post #567

Earlier quoted context omitted.

incandescent light bulbs efficiency increases with their temperature/current. At low enough current they will last long enough but waste a lot energy as well. You can dim them, and provide a slow start to prevent the inrush current (which is like 10times more than nominal with tungsten resistance increasing due so high 2500K temps).

Thankfully, LED lighting will probably be gone within 20 years, while incandescent will be coming back more efficient than LED could dream. Already bumping up against theoretical maximum efficiency, LED lighting can't get any more efficient, and the better LED is at color rendition, the less efficient it is. But there are vast amounts of improvement available for incandescent lighting, and a group at MIT has already…

It seems like this could be done differently, and perhaps more cost-effectively. Can't give cites right now, but here's a path I'd explore if I were in the field.

I'd pattern the inner surface of the glass envelope with a cube texture - think of taking a cube and pressing a corner normally into a clay surface, then removing the cube. This pattern is a so-called corner reflector, and returns incident light to its source. Figure the cube indentations at about 0.5mm deep, close packed. I'd deposit a dielectric film reflector stack tuned to reflect most infrared radiation onto this surface.

This combination would transmit visible light, but would reflect IR directly back to the filament, reducing the amount of electrical power needed to maintain filament temperature. Glass textural molding and dielectric film deposition are mature technologies. I think this could readily triple incandescent lamp power efficiency, maybe even better.

Re: There's something off about LED bulbs

#707

Post by leobg »

thuttinger wrote: post #703
leobg wrote: post #640

Earlier quoted context omitted.

Great site. I wish he had an English translation. But I forgive him. This is what the Internet should be! Individual people who do one thing really well. So happy to see that this still exists online.

There is one guy that does the same for batteries, chargers, power supplies and more: https://lygte-info.dk/

Thank you. Had been looking for something like this! Batteries are one of these items where you really don’t know what you’re getting.

Re: There's something off about LED bulbs

#708

Post by mariodiana »

jasonlaramburu wrote: post #502
chongli wrote: post #465

Earlier quoted context omitted.

The big problem for me is, as a consumer, how do I know that brand X is producing quality bulbs that'll last a long time? The issue is that LED bulbs aren’t simple devices like incandescent bulbs. LED bulbs have an electronic power supply inside which drives the LEDs at a constant current. Power supply design is a major subfield of electronics engineering and there are all kinds of tradeoffs you can make to optimize…

>It is possible (and not very difficult) to design LED bulbs that will practically outlive their owners It is also possible (and not very difficult) to design incandescent bulbs that will outlive their owners. In fact, the first mass produced light bulbs generally lasted 2,500+ hours. In the 1920s, the major bulb manufacturers formed the 'Pheobus Cartel' in Geneva and secretly colluded to limit the lifespan of bulbs…

Perhaps the planned obsolescence helped the consumer, because perhaps there would have been no willing producers if producing the lightbulbs at a price the users were willing to pay for wasn't going to turn out to be profitable, with respect to setting up production in the first place and then producing until the investment was paid back.

When we're talking market price, we have to acknowledge that it is a meeting of the price needed to bring a product to market and the price the consumer is willing to pay. We can't assume that the price of the longer lasting bulb would have been attractive to consumers, when compared to the price of the shorter-lived bulb, even if they had all the information available.

It's perfectly valid for a person to decide they'll spend more over the long run, rather than ponying up a larger sum now. And it's perfectly valid for producers to take the chance of deciding this for the consumer. As Henry Ford noted, "If I had asked people what they wanted, they would have said faster horses."

Was anybody stopping anyone from offering the consumer a higher-priced and longer-lasting bulb?

Re: There's something off about LED bulbs

#709

Post by seszett »

eimrine wrote: post #701
seszett wrote: post #696

Earlier quoted context omitted.

I think you misunderstand the fundamental difference between "white" LEDs which are generally a blue LED associated with various phosphors that convert the monochromatic blue light into a mostly continuous spectrum going from blue to red, and the monochromatic R, G and B LEDs that each emit a fairly narrow band that is either red (with no blue or green at all) green (no blue or red) or blue (no red or green). Blue LE…

> infrared LEDs that emit at 940 nm Is there any LED capable of emitting 780nm? Or maybe a luminophore for letting manufactures to convert invisible 940nm into anything visible? AFAIK both answers are negative.

https://www.lumixtar.com/5w-ir-780nm-high-power-led.html

This seems to match what you're asking for. But converting longer wavelengths to shorter ones is always going to be difficult, so I don't think there exists a practical way to make visible light from 940nm.

Re: There's something off about LED bulbs

#710

Post by mbtwl »

Can’t relate at all. Maybe it’s regional. In EU conventional light bulb have been phased out more than ten years ago. In the first few years there were some crappy LED bulbs until manufactures solved issues of basically completely new product. I don’t remember any LED bulb I ever bought breaking until now. And ones I bought in last 5 years (when moving to a new place) also have nice warm colour and don’t flicker. Good bulbs used to be around 5-10€ per piece, now more due to inflation. But I don’t mind since they last forever. And way more efficient, wonder how long it takes before cost is made up my savings in electricity bill.
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