What is the point of blazingly bright blue LEDs in everything these days?

[Jeff_Birt]

I just bought a Unitek USB3 hub/card reader. It works great but has an annoyingly bright blue LED on the top. It is so bright that I put a Post-It note over the top of it and it was still brighter than needed. I colored a spot on the Post-It with a Sharpie marker and put that over the LED and I can still see the LED through that!

I got a new cable modem months ago at home from the cable company. Not only is it the size of a VCR but the front panel is loaded with very, very bright blue LEDs. It lights up the room at night it is so bloody bright.

What is with these companies needing to make the LEDs soooooo bright?

[Bud]

I agree, it is annoying. On my audio box i cover the led with a sticky, and on the computer i cut a few of them off. Where i use blue LEDs in my protos, i choke them with fairly high value current limiting resistors.

[CraigHB]

I've got the same problem with some devices.  Thing is they can set the brightness simply by using the appropriate bias resistor in the design, but they always seem to go for blazingly bright.  I have a bunch of things with electrical tape over the LEDs.  It's funny when I shut off the lights in my work area it looks like a Christmas tree there's so many of those darn LEDs on everything.

That reminds of another annoying thing, fans.  My scope has a fan that sounds like a turbine engine.  I've changed out fans for quieter ones on a lot of devices, the scope is in line for one.  What's the deal?  What was so awful about passive cooling, they seem to put fans in everything now.  If they simply must use a fan there are very quiet fans available.  They always seem to pick the noisiest fan they can find.  Are they doing it on purpose just to annoy customers? 

[R005T3r]

they are not using limiting resistors for the LED, so they can save up on costs. I think...

[rrinker]

 And board space.

When blue LEDs were rather rare, it was cool to have a computer that used a blue light for the power LED instead of a plain old red one. But now EVERYTHING is blue. And it IS annoying.

[ajb]

Blue LEDs were a big deal when they came out, so high end consumer devices used them as a distinguishing visual element.  Fast forward and now blue LEDs are so cheap that they're in everything, and LEDs generally are much more efficient than when they first became available, and can be obnoxiously bright even at <1mA. 

I suspect that the blinding brightness in the finished product is simply down to the fact that no one bothers to notice it and/or fix it.  It can be difficult to know how much current to run an LED at ahead of time, especially if you're going to be coupling it out of the housing via a custom lightpipe that hasn't been made or even designed yet.  I suspect that usually what happens is some EE takes a wild guess at the current limiting resistor value while designing the device, and by the time the production prototype of the housing is ready to evaluate the electronics designer is on to something else and no one bothers to revise the resistor value.  For that matter, by that point the boards may already be in production and it's too late to change the BOM.  Also consider that the brightness required to be clearly visible in a bright room may be far too bright for a dimly- or un-lit room at night, and if the device is only ever tested in a brightly lit lab, no one may even have a chance to notice that there's a problem.

[John Coloccia]

Yeah...basically they were impossible to build for such a long time that everyone wants to use them now. This is actually one of the areas that I take a lot of time to get right on my products. You have to be able to see it in reasonable lighting, but it also has to not blind you on a dark stage. It's not so easy.

But to give an idea how bright these damn things are, I use a super bright blue LED on some of my products. I'm running it on 9VDC with a 100k resistor!

[Len]

I don't think this has anything to do with the colour of the LEDs. I have put tape over the LEDs on two devices in my bedroom, and they're both red. I've also had problems with over-bright green and orange LEDs. It seems that modern LEDs are just more efficient and brighter than they were in the old days.

[CraigHB]

Yeah they're bright now.  The FSTN screen on one of my devices can double as a flashlight and the multi-LED backlight only pulls about 10mA.  The white ones are blazing, hurts your eyes to look at one directly when biased halfway through the current range.  Really they only need a couple three mA at most anymore, which is nice for battery powered stuff.

[rdl]

The apartment management recently had the alarm systems upgraded. The new control panel in my living room has red and green LEDs that would make a good night light and the touch screen is annoyingly bright even at the minimum setting. I don't use the thing, so I disconnected it from its battery and power supply. Now it's not annoying at all.

[CraigHB]

Haha, that's one way to solve the problem.  I actually have a little USB adapter that had a white LED from hell in it.  It was like another desk lamp.  I actually took that one apart and removed the LED, I could have probably changed the bias resistor, but it was easier just to remove the LED.  Not like I need an indicator light to tell me it's plugged in.

[Zero999]

On of the problems with high brightness LEDs in general, is they tend to have a poor viewing angle. Use diffused LEDs or an SMT LED and light pipe for a decent viewing angle.

[jonovid]

cold white LED's are annoying. as warm white is more natural, as for blue, its a fad.    next is purple LED's in 2017? 

[wraper]

they are not using limiting resistors for the LED, so they can save up on costs. I think...

Nonsense, LEDs will just fail if you don't limit he current. SMD resistors are cheaper than dirt BTW.

[Brumby]

I have a PC box up on a shelf - and the power on LED is one of those ultra bright blue things.  What's worse is that it is at my exact eye height when I walk past.  Even in broad daylight, I have learned to not look in that general direction as I walk past.

One day I'll pull the front off and put a resistor inline.  Might start with a 10K.

[aargee]

Probably running them straight from a 3.3V rail.

[Alex Eisenhut]

Yep, I feel the same. Blue LEDs lost their cool factor a while back, so to compensate, they make them brighter I guess.

The only place I feel they do a good job is in the backlight of the display panel of my Breville toaster oven, and that's also the only place where they burnt out... 

[jonovid]

they are not using limiting resistors for the LED, so they can save up on costs. I think...

I did dial back LED's with higher resistor values.  just as a test,  but as I see it, the super bright water-clear blue LED's
are intended for light pipe designs. I got them super bright LED's in all 5 colors, SMD types too, but do not always use them.
as a frosted red or diffused green is just as functional without the annoying in your eyes problem.
it was a single water-clear blue 5mm LED sold to me for outrageously $5AU    by jaycar, as a replacement 
that started my online electronics shopping,  determined to get cents in the dollar value too. 

[T3sl4co1l]

Almost all "engineers" will look at the LED datasheet, see "10-20mA If", and calculate the resistor accordingly.  End of story, ship it.

That's simply all there is to it.

In my recent designs, I've made a point of checking a couple of things:
1. Use proper high efficiency LEDs, so they will be consistently bright.  (This means InGaN green, not GaP green.  If the datasheet doesn't specify, keep looking!)
2. Make sure they have similar emission angles and intensities.  (Green is usually brighter, and red dimmer, when measured by candela rating.  Adjust currents as needed later.)
3. Use no more than ~1mA.  A little more is good for red (~2mA?).
4. Take into account previous designs.  If they were overly bright (or dim), adjust accordingly.

Note that InGaN green has Vf ~ 3V, just like blue (it's a blue LED, tuned to emit in green!), so you need a 5V supply, and you'll probably need different resistors for each color.  YMMV.

Note also that this is fine for indoor applications, but a brightly lit shop floor, or outdoors, won't have as good visibility as running everything near limits.  Obviously, the dynamic range can be astronomical (from indoors to sunlight, we're talking more than three decades of range), and if you really need to support that, while looking good, you have no choice but to add a photosensor and control.

Tim

[Lightages]

I am glad I am not the only one still bothered by this stupidity;

https://www.eevblog.com/forum/chat/$-blue-leds-on-equipment/

[Dubbie]

I bought a purple LED for a power indicator for a device I made. I thought it might be a nice change.

It was the most awful thing ever! Because the color was so close to UV, the focus point is different to white light which is a very weird effect. Your eyes keep focusing back and forth like a camera auto-focus that can't get a lock!

I ended up using a dim white LED instead.

[zapta]

>> What is the point of blazingly bright blue LEDs?

These stickers work great for me. They have 50%-80% opacity for bright LEDs and 100% for phone cameras.

http://www.lightdims.com/store.htm

[jolshefsky]

I kind of think minor design flaws like Van Halen's famous contract clause to remove the brown M&M's. If a product is released and nobody thought to use anything but 20mA through all the LEDs then they probably didn't pay much attention to other details either. It's a conveniently bright indication of poor design.

[imidis]

They can be annoying. If it's doable and bothered me I'd replace it or remove it. 

[Zero999]

I bought a purple LED for a power indicator for a device I made. I thought it might be a nice change.

It was the most awful thing ever! Because the color was so close to UV, the focus point is different to white light which is a very weird effect. Your eyes keep focusing back and forth like a camera auto-focus that can't get a lock!

It sounds like you chose a violet LED, probably 400nm to 420nm, which is hard on the eyes and will have some UVA output. You wanted a true purple LED, consisting of a blue die, with a orange/red phosphor, to give blue + longer wavelength = purple light.

Datasheets:
https://www.rapidonline.com/pdf/55-9174.pdf
http://uk.rs-online.com/webdocs/144d/0900766b8144dd0b.pdf

Another option is an LED with red and blue dies driven at the right current to give a nice colour.

[cdev]

People should be aware that the light from really bright blue LEDs can damage the photoreceptors in the retina.


Some interventions help protect the eyes from bright blue light..


Example:


Protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro.


https://www.ncbi.nlm.nih.gov/pubmed/24690313


For this reason I always cover the really bright ones with something colored like a small square of several layers of yellow Kapton tape layered over one another. There are probably better filter materials but that was what was handy


here is the link for related papers to the above paper..


https://www.ncbi.nlm.nih.gov/pubmed?linkname=pubmed_pubmed&from_uid=24690313


Definitely don't let those blue LEDs shine right in your eyes.. if it hurts there is likely a reason!


HTH!

[Circlotron]

Police cars have amazingly bright LEDs on their roof nowadays. I'm on the lookout for a tinted rear view mirror so I won't see them anymore.

[T3sl4co1l]

Police cars have amazingly bright LEDs on their roof nowadays. I'm on the lookout for a tinted rear view mirror so I won't see them anymore.

Flip the tab thingy on the bottom of the mirror.

Tim

[John Coloccia]

Police cars have amazingly bright LEDs on their roof nowadays. I'm on the lookout for a tinted rear view mirror so I won't see them anymore.

Back in my homebuilt airplane building days, I was going to use LED lighting for position lights. Strobe was still a traditional strobe. Some were experimenting with LED lights for landing lights. That was over 10 years ago. I believe the technology has progressed to the points that you can actually use LEDs for everything these days.

[Artlav]

At night I can navigate my home without turning the lights on and dazzling myself. I've got enough devices with leds in them that they form a set of nautical channel markers to help me avoid bumping into things.

Exactly.
I made a bunch of nightlights for this very purpose, and the blue ones seem to be the brightest per nanowatt.
Should last for 5 years, bright enough to go to the toilet without turning on the lights and waking up.
Sadly, so far i given away a dozen and sold none.

[jonovid]

Sadly, so far i given away a dozen and sold none.

The un-used Batteriser case's now has a use 

[timb]

Blue is also the worst for night vision, red being the best. Your eyes are also most sensitive to green light, so even a small current mismatch between green LEDs can be noticeable. (This is also why it's common to use a 5r-6g-5b data format for LCD panels that use a 16-bit bus.)

[@rt]

Maybe they stocked up back when the Nobel prize winning blue/white LEDs
were special, or became cheap, thinking they would always be special.
Products or projects based on LEDs are so 90's now lol.

[Sal Ammoniac]

A lot of these bright blue LEDs seem to be used in headlights on boy racer cars that blind other drivers. Some of these things seem as bright as WW2 searchlights.

[timb]

A lot of these bright blue LEDs seem to be used in headlights on boy racer cars that blind other drivers. Some of these things seem as bright as WW2 searchlights.

Often those are HID lights, which are gas discharge based. Aftermarket retrofit kits used to be very popular, the thing is (in most locations) HID lights are required by law to include a "leveling servo" system that keeps them pointing down towards the road, because they can easily blind oncoming drivers, however the kits designed to convert a traditional headlight to HID don't include it. Traditional headlights also aim higher, since they're not as bright.

So, you end up with assholes that blind everybody. It's even worse with these guys that have jacked up pickup trucks and HID retrofits.

For awhile purple (and blue) aftermarket HID lights were all the rage, even though they're only legal for off-road use. They're also useless because purple is so high in the color spectrum, so they illuminate around 10% of the road compared to a white HID lamp (hence why they're illegal).

Thankfully the cops started cracking down on aftermarket HIDs here, after a driver was blinded by some douchebag and ran off the road, nearly killing her.

[CraigHB]

Yeah you seen those HID car headlights a lot now, a lot of the higher end cars come with them factory equipped.  They're actually quite a benefit for a motorcycle where there's only one headlight.  There's also halogen lights that have a similar blueish tint, but they're not nearly as bright.  You see the bulbs in auto parts stores sometimes with Xenon stamped on the label, but they're not HID lights (which employ a Xenon gas filled bulb).  They're just halogens with a blue tint and false marketing claims on the label.  Pretty much a scam to fool people into thinking they're HID when they're only incandescent.

I see LEDs used a lot now in automotive applications.  Just about all the new commercial trucks I see use them instead of incandescent for tail and running lights.  They are much brighter and of course they have the benefit of much longer service life.

[timb]

Yeah you seen those HID car headlights a lot now, a lot of the higher end cars come with them factory equipped.  They're actually quite a benefit for a motorcycle where there's only one headlight.  There's also halogen lights that have a similar blueish tint, but they're not nearly as bright.  You see the bulbs in auto parts stores sometimes with Xenon stamped on the label, but they're not HID lights (which employ a Xenon gas filled bulb).  They're just halogens with a blue tint and false marketing claims on the label.  Pretty much a scam to fool people into thinking they're HID when they're only incandescent.

I see LEDs used a lot now in automotive applications.  Just about all the new commercial trucks I see use them instead of incandescent for tail and running lights.  They are much brighter and of course they have the benefit of much longer service life.

Yeah, most cars and SUVs started switching to LED brake/turn/parking lamps about 5 years ago. Interior lamps as well.

Use as Daytime Running Lamps is also becoming increasingly popular. I think Audi was one of the first to do that, when they implemented a bar of them over the normal headlamps. BMW followed by placing a ring of LEDs around the main headlamps, I.e. "Halo" Lamps.

[rrinker]

 And I wish everyone had something similar. Just tonight I was once again behind one of those MORONS who has a car that uses the main lamps as DRL. So THEY think they have their lights on after dark, but they don't - no lights to the rear. Either different lights which do not cast enough light to see, or just get rid of the damn things altogether. Not as bad now with the LED ones, but damn my old X3 blew headlights monthly. I had more headlight bulbs replaced in 3 years of owning that car than the total I've had to replace on every other car I've ever owned combined.

[Someone]

There's also halogen lights that have a similar blueish tint, but they're not nearly as bright.  You see the bulbs in auto parts stores sometimes with Xenon stamped on the label, but they're not HID lights (which employ a Xenon gas filled bulb).  They're just halogens with a blue tint and false marketing claims on the label.  Pretty much a scam to fool people into thinking they're HID when they're only incandescent.

Noble gasses are often used to fill the incandescent halogen globes: https://en.wikipedia.org/wiki/Halogen_lamp#Halogen_cycle
So its entirely accurate to represent a Xenon filled globe as just that, especially since it does have different characteristics and isn't just a cosmetic or vanity ingredient:
http://zeiss-campus.magnet.fsu.edu/articles/lightsources/tungstenhalogen.html
http://donklipstein.com/xeincand.html
https://www.pegasuslighting.com/lc-lighting-info/xenon-vs-halogen.html

[grifftech]

2 white LEDs in series on a 5 volt supply use 0.0001W or 100 µW