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.