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Explain to me the (de?)-evolution of LED lightbulb technology

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BrokenYugo:

--- Quote from: Sal Ammoniac on March 23, 2021, 03:45:46 pm ---I wonder if this race to the bottom price-wise results in LED bulbs that generate lots of RF noise? I wouldn't be surprised at all if it did.

So now we have a product that generates two kinds of pollution: RF pollution and light pollution.

--- End quote ---

The super cheap non dimmable ones, at least in 120V land, seem to have gravitated towards a linear driver setup. Those are silent to the best of my testing ability (holding a AM transistor radio near a 100W one I got from the dollar store).

I wouldn't doubt it if the more complex dimmable and smart bulbs with buck converters and radios of their own make all sorts of noise though.

ogden:

--- Quote from: TimNJ on March 23, 2021, 03:13:59 am ---Anyone able to summarize what happened over the last few years?

--- End quote ---

Customers who buy cheapest (***t) they can get - happened. It does not mean that quality products do no exist anymore. Such are simply out of scope for generic buyers who check only nearby grocery store or lowest cost Amazon/Aliexpress offers.

TimNJ:

--- Quote from: ogden on March 23, 2021, 06:06:53 pm ---
--- Quote from: TimNJ on March 23, 2021, 03:13:59 am ---Anyone able to summarize what happened over the last few years?

--- End quote ---

Customers who buy cheapest (***t) they can get - happened. It does not mean that quality products do no exist anymore. Such are simply out of scope for generic buyers who check only nearby grocery store or lowest cost Amazon/Aliexpress offers.

--- End quote ---

While part of my question was indeed about the (possible) decline in quality, due to a "maturing" market -- and capitalism being capatalism and cheap-asses being cheap-asses -- really I was just wondering what explains the overall shift in design approach. I think the few replies above neatly explain it.  But, I do agree, part of it is consumers un-willingness to pay a premium for something that actually lasts (no shock there) and manufacturers willing to make crap in response.

But, to my main point, here's my summary of the above responses:

Earlier LEDs required much more current for X amount of lumens. So, you probably couldn't just throw in one of these (modern) linear constant current drivers because the driver dissipation would probably be way too much. I don't have any ballpark figures to compare then vs. now, but makes sense. So, they went for switch-mode constant current driver with relatively high driver efficiency. Nowadays, larger number of LEDs in series + much improved efficiency means the forward current can be much lower, making a linear constant current driver practical.

andy2000:

--- Quote from: Sal Ammoniac on March 23, 2021, 03:45:46 pm ---I wonder if this race to the bottom price-wise results in LED bulbs that generate lots of RF noise? I wouldn't be surprised at all if it did.

So now we have a product that generates two kinds of pollution: RF pollution and light pollution.

--- End quote ---

I recently bought some new LEDs to replace some early ones that were starting to fail.  Coincidentally, around the same time I noticed a lot of interference on a vintage analog TV in the next room that gets used to watch the news.  There were very noticeable wide horizontal noise bars moving up the picture.  It turned out that the new bulbs were causing the interference.  The set is fed using a shielded coaxial line, so I was surprised so much noise was leaking in.  With the coax unplugged, the usual snow was completely obscured by the interference.

Out of curiosity, I used my spectrum analyzer to look at the interference.  This was with just an dangling probe as an antenna.  You can see the FM band on the left side, and a couple of ATSC TV channels on the right.  The bulbs were generating interference over the entire spectrum up to about 500 MHz.  Needless to say, they went back to the store.  The old bulbs generated no visible interference. 

Tomorokoshi:

--- Quote from: andy2000 on March 23, 2021, 08:19:16 pm ---
--- Quote from: Sal Ammoniac on March 23, 2021, 03:45:46 pm ---I wonder if this race to the bottom price-wise results in LED bulbs that generate lots of RF noise? I wouldn't be surprised at all if it did.

So now we have a product that generates two kinds of pollution: RF pollution and light pollution.

--- End quote ---

I recently bought some new LEDs to replace some early ones that were starting to fail.  Coincidentally, around the same time I noticed a lot of interference on a vintage analog TV in the next room that gets used to watch the news.  There were very noticeable wide horizontal noise bars moving up the picture.  It turned out that the new bulbs were causing the interference.  The set is fed using a shielded coaxial line, so I was surprised so much noise was leaking in.  With the coax unplugged, the usual snow was completely obscured by the interference.

Out of curiosity, I used my spectrum analyzer to look at the interference.  This was with just an dangling probe as an antenna.  You can see the FM band on the left side, and a couple of ATSC TV channels on the right.  The bulbs were generating interference over the entire spectrum up to about 500 MHz.  Needless to say, they went back to the store.  The old bulbs generated no visible interference.

--- End quote ---

Feit. I could have guessed that. Those fail the quickest for me.

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