7 ms·

Sadly there are a lots of flaws of LEDs, I think they are put in the spotlight a bit too early. While they are a lot better than previous light saving technolog

by sydd 8y ago

Sadly there are a lots of flaws of LEDs, I think they are put in the spotlight a bit too early. While they are a lot better than previous light saving technologies (like CFLs which took a minute or two to warm up), most of the bulbs in the market currently have lots of drawbacks: - Their CRI is pretty low, around 80. - They flicker causing eye strain. There are now LEDs that solve both, its just a pain to find them (and cost 2-10x more than other LEDs.)

iainmerrick 8y ago
How do you go about finding high-quality LEDs? Are they easily available in standard bulbs?
- toss1 8y ago
  Just tinkering, I've found several factors are important. First is the color temp and CRI of the bulb/chip; make sure they match your application. Sometimes mixing bulbs/chips works well to get a more pleasing & usable spectrum. I've also found that the strip LEDs with multiple colors and a tunable controller produce good results. Second, find a power supply/controller that has a very high frequency. LED's don't inherently flicker, and when powered straight from a source like a battery provide a completely steady light. The flicker is typically from a time-chopping brightness controller. Cheap ones may use 60Hz, which the eye can still see, especially in the peripheral vision areas (rod cells, sensing only grays detect motion much better, whereas color-sensing cone cells at the center of the visual field have a slower response so detect flicker less well). Ideally, get a controller well above 25KHz to also eliminate any audio artifacts. I'd very much like to see someone more expert chime in!
  - iainmerrick 8y ago
    Are there any dimmable LED strips that operate by fully illuminating X% of the LEDs? As opposed to time-slicing all the LEDs. I don’t know enough about hardware to know if that would be feasible. The flickering and whining is pretty bad in all the dimmable LED bulbs I’ve used (but I haven’t yet looked hard for high-end ones).
    - dbuder 8y ago
      For long life, LEDs need to be off some of the time, better to run at 20mA 50% of the time than 10mA 100% of the time. That always on warning light on your cheap electronics runs at low power and has a relatively high failure rate. You need to tune or shield the drive to avoid troublesome EMI.
    - thatcat 8y ago
      Yea, my desk lamp does that.
    - OnlineCourage 8y ago
      That severly shortens the lifetime of an LED, like by a factor of 10. So I would guess it is not common because much of the benefit that gets marketed is the longer lifetime. It is possible to build a better dimmer switch which actually works across the full profile of voltage variation but the problem then is you have to pay an engineer money and why do that when you can spend money on booze and dinners to win more sales contracts with your lighting distributors and get a higher ROI? The lighting world is a very consolidated place.
- lotsofpulp 8y ago
  I haven't had any problems with the GE Classic LEDs: https://www.lowes.com/search?searchTerm=ge+classic+led https://www.lowes.com/search?searchTerm=ge+classic+led
  - sydd 8y ago
    Sorry, they are likely crap. If there is no Ra/CRI value given its 80.
- sydd 8y ago
  Yes. Just google for stuff like 95 CRI or high CRI bulbs. They are a bit more expensive than normal bulbs though. Some examples of good ones: https://www.waveformlighting.com/home-residential https://www.waveformlighting.com/home-residential https://www.mueller-licht.de/ https://www.mueller-licht.de/ And surprisingly IKEA Ledare bulbs are pretty good too (although not as good as the ones above)
JohnJamesRambo 8y ago
The cheap LED light bulbs I get at Walmart seem just fine. Have you bought them recently? I don't notice any flicker and their light renders colors better than my incandescents or CFLs ever did. They grow plants the best too, in my head to head tests.
OnlineCourage 8y ago
LEDs do not flicker, it is the pulse width modulation within the control circuit which causes flicker, which ultimately is due to poor design not the LED itself. CRI is based upon the patents held by the semiconductor fab which affect the type of semiconductor which can be used and how the phosphor is applied which varies. Binning (or statistical sampling) of LED chromacity improves over time across the industry. LEDs work great as spotlights actually because the most widely available lens material creates a sharp, direct light as opposed to a diffuse light. ;-)
lozaning 8y ago
Do they have LEDs now that only put out light in a small spectrum of filterable wavelengths? The city of Tucson for a long time resisted swapping all their street lights out from the existing sodium lights because local astronomers found it significantly harder to filter out the wide gamut of "junk light" from LEDs.

by sydd 8y ago

iainmerrick 8y ago

How do you go about finding high-quality LEDs? Are they easily available in standard bulbs?

toss1 8y ago
Just tinkering, I've found several factors are important. First is the color temp and CRI of the bulb/chip; make sure they match your application. Sometimes mixing bulbs/chips works well to get a more pleasing & usable spectrum. I've also found that the strip LEDs with multiple colors and a tunable controller produce good results. Second, find a power supply/controller that has a very high frequency. LED's don't inherently flicker, and when powered straight from a source like a battery provide a completely steady light. The flicker is typically from a time-chopping brightness controller. Cheap ones may use 60Hz, which the eye can still see, especially in the peripheral vision areas (rod cells, sensing only grays detect motion much better, whereas color-sensing cone cells at the center of the visual field have a slower response so detect flicker less well). Ideally, get a controller well above 25KHz to also eliminate any audio artifacts. I'd very much like to see someone more expert chime in!
- iainmerrick 8y ago
  Are there any dimmable LED strips that operate by fully illuminating X% of the LEDs? As opposed to time-slicing all the LEDs. I don’t know enough about hardware to know if that would be feasible. The flickering and whining is pretty bad in all the dimmable LED bulbs I’ve used (but I haven’t yet looked hard for high-end ones).
  - dbuder 8y ago
    For long life, LEDs need to be off some of the time, better to run at 20mA 50% of the time than 10mA 100% of the time. That always on warning light on your cheap electronics runs at low power and has a relatively high failure rate. You need to tune or shield the drive to avoid troublesome EMI.
  - thatcat 8y ago
    Yea, my desk lamp does that.
  - OnlineCourage 8y ago
    That severly shortens the lifetime of an LED, like by a factor of 10. So I would guess it is not common because much of the benefit that gets marketed is the longer lifetime. It is possible to build a better dimmer switch which actually works across the full profile of voltage variation but the problem then is you have to pay an engineer money and why do that when you can spend money on booze and dinners to win more sales contracts with your lighting distributors and get a higher ROI? The lighting world is a very consolidated place.
lotsofpulp 8y ago
I haven't had any problems with the GE Classic LEDs: https://www.lowes.com/search?searchTerm=ge+classic+led https://www.lowes.com/search?searchTerm=ge+classic+led
- sydd 8y ago
  Sorry, they are likely crap. If there is no Ra/CRI value given its 80.
sydd 8y ago
Yes. Just google for stuff like 95 CRI or high CRI bulbs. They are a bit more expensive than normal bulbs though. Some examples of good ones: https://www.waveformlighting.com/home-residential https://www.waveformlighting.com/home-residential https://www.mueller-licht.de/ https://www.mueller-licht.de/ And surprisingly IKEA Ledare bulbs are pretty good too (although not as good as the ones above)

JohnJamesRambo 8y ago

The cheap LED light bulbs I get at Walmart seem just fine. Have you bought them recently? I don't notice any flicker and their light renders colors better than my incandescents or CFLs ever did. They grow plants the best too, in my head to head tests.

OnlineCourage 8y ago

LEDs do not flicker, it is the pulse width modulation within the control circuit which causes flicker, which ultimately is due to poor design not the LED itself. CRI is based upon the patents held by the semiconductor fab which affect the type of semiconductor which can be used and how the phosphor is applied which varies. Binning (or statistical sampling) of LED chromacity improves over time across the industry. LEDs work great as spotlights actually because the most widely available lens material creates a sharp, direct light as opposed to a diffuse light. ;-)

lozaning 8y ago

Do they have LEDs now that only put out light in a small spectrum of filterable wavelengths? The city of Tucson for a long time resisted swapping all their street lights out from the existing sodium lights because local astronomers found it significantly harder to filter out the wide gamut of "junk light" from LEDs.