3 ms·

If I have to guess, support & engineering would be the main force behind LEDs. For example, you have USB port in the bed base, and it does not charge the cellp

by theamk 3y ago

If I have to guess, support & engineering would be the main force behind LEDs. For example, you have USB port in the bed base, and it does not charge the cellphone, so you call tech support. With LED, it's simple. LED on -> "verify the USB port is not bent or damaged, check your cable, check your cellphone"; LED off -> "verify bed is plugged in, verify outlet has power". Without it? Much harder, especially if you are talking over the phone to non-technical person who does not follow the instructions. (I made a number of one-off home devices for my own use and there is almost always an indicator LED of some sort. Combined activity/power if I can make one, or at least a power one if it's impossible. Some of them are blue, because blue is a nice color and needs really low current to be visible)

JohnFen 3y ago
The real questions are: why blue, and why so bright? LED indicators are useful, but they should be red (which comes with the added benefits of being less expensive and drawing less power than blue ones), and shouldn't be bright enough to light the area around them.
- theamk 3y ago
  the "why so bright" part is simple: given same current, blue is noticeably brighter. A 5 mA current will make passable red, but flashlight-level blue. If you are old-school designer who got used to red and green LEDs, all your blues would be super bright. I still worry when I see 2K or a 5K resistor next to a LED: "Wait, that's too much resistance and too little current, user is not going to see it... hm, which color is it? Are you sure it's that sensitive? Maybe decrease resistance a bit just to make sure you don't have to redo the PCBs?" Which also means that blue LEDs draw _less_ power than red and green ones, for the same brightness. Thinking about this, this could be a one reason to use them in battery-backed devices. The "less expensive" part may be was true in the past, but is bogus today: a random search shows $0.01468 for red[0] and $0.01572 for blue[1] in 10K quantity. 0.1 cent is not going to affect your final cost, unless you are into super-cheap devices. [0] https://www.digikey.com/en/products/detail/beking-optoelectronics/BQ-0603R127-R3YYD0N-E0/21556291 https://www.digikey.com/en/products/detail/beking-optoelectr... [1] https://www.digikey.com/en/products/detail/beking-optoelectronics/BQ-0603B105-E3YYD0N-B0/21556289 https://www.digikey.com/en/products/detail/beking-optoelectr...
  - JohnFen 3y ago
    If all of that is true, then I guess I'm just doomed to having to cut the blue LEDs out of the devices I buy forevermore? That's a bit depressing. I was hoping that this was the result of a fad that would eventually pass, eliminating a common irritation from my life.
    - shrimp_emoji 3y ago
      Thermodynamics is into blue LEDs. ;p Your only hope is the transition to post-LED technology.
- Mountain_Skies 3y ago
  Wonder if some of it is due to blue still being perceived as high tech. For people over a certain age, red was the default LED color for decades as may have become associated in the average person's mind with outdated technology.

by theamk 3y ago

JohnFen 3y ago

The real questions are: why blue, and why so bright? LED indicators are useful, but they should be red (which comes with the added benefits of being less expensive and drawing less power than blue ones), and shouldn't be bright enough to light the area around them.

theamk 3y ago
the "why so bright" part is simple: given same current, blue is noticeably brighter. A 5 mA current will make passable red, but flashlight-level blue. If you are old-school designer who got used to red and green LEDs, all your blues would be super bright. I still worry when I see 2K or a 5K resistor next to a LED: "Wait, that's too much resistance and too little current, user is not going to see it... hm, which color is it? Are you sure it's that sensitive? Maybe decrease resistance a bit just to make sure you don't have to redo the PCBs?" Which also means that blue LEDs draw _less_ power than red and green ones, for the same brightness. Thinking about this, this could be a one reason to use them in battery-backed devices. The "less expensive" part may be was true in the past, but is bogus today: a random search shows $0.01468 for red[0] and $0.01572 for blue[1] in 10K quantity. 0.1 cent is not going to affect your final cost, unless you are into super-cheap devices. [0] https://www.digikey.com/en/products/detail/beking-optoelectronics/BQ-0603R127-R3YYD0N-E0/21556291 https://www.digikey.com/en/products/detail/beking-optoelectr... [1] https://www.digikey.com/en/products/detail/beking-optoelectronics/BQ-0603B105-E3YYD0N-B0/21556289 https://www.digikey.com/en/products/detail/beking-optoelectr...
- JohnFen 3y ago
  If all of that is true, then I guess I'm just doomed to having to cut the blue LEDs out of the devices I buy forevermore? That's a bit depressing. I was hoping that this was the result of a fad that would eventually pass, eliminating a common irritation from my life.
  - shrimp_emoji 3y ago
    Thermodynamics is into blue LEDs. ;p Your only hope is the transition to post-LED technology.
Mountain_Skies 3y ago
Wonder if some of it is due to blue still being perceived as high tech. For people over a certain age, red was the default LED color for decades as may have become associated in the average person's mind with outdated technology.