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Comment by saidajigumi | Hacker News Reader

Almost separately from the circadian-rhythm concerns from the article, a major design peeve of mine are random products that have unnecessarily blinding blue LEDs. Worst example I know of: an otherwise competently executed automatic HDMI switch with several incredibly bright blue LEDs, always on. So bright as to be able to read and see all objects in the same room. So when you might dim the lights to watch something? The switch is still blinding blue, usually right at the viewers!

I mitigated this by disassembling the switch and installing some 3-stop ND (neutral density) lighting gel to dim these stupid LEDs to acceptable levels. This product at least afforded a good-looking solution -- many can't be disassembled to fix the problem.

See also: Dyson rechargeable vacuum cleaners.

Maybe it's time for an LED shaming tumblr...

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I've been ranting about Blinding Blue LEDs for years. It seems that, almost as soon as blue LEDs became available, Every. Damn. Manufacturer. decided, "This is the new style because, hey, blue LEDs!"

A blue LED isn't so bad if they tone the brightness down, but too many companies can't be bothered, or just think it's "cool" and "edgy."

I've heard of people applying a thin layer of black nail polish over eye-blasters like those. Fortunately, my main system's case has a door that normally stays closed, mercifully hiding the room-lighting power indicator.

I use these "LightDims" stickers to either black out or dim LEDs: http://a.co/7gGzOL8

They come in various colors, shapes, and opacity. They look much better than my previous method of using electrical tape.

> an otherwise competently executed automatic HDMI switch with several incredibly bright blue LEDs, always on

Oh my god I had one of those. I put several layers of opaque tape on them and I could still see the damn LEDs through. I'd rather say that in jest but I still suffer from retinal persistence just by talking about it (seriously, barely kidding). I don't even know how such an insane device made it through any form of certification.

I have a tv that has an led to display that it is off. LED is obnoxiously over used for displaying things no one gives a shit about. But personally my pet peeve is the annoying beeping everything does. It doesn't provide any context or useful information. I've been at a self checkout and have the clerk turn it back on after I muted it while scanning items. It resets after the transaction anyways. Everything has beeps or bright LEDs.

Phones are my biggest complaint - not mine as all sounds have been turned off, but everyone else’s. You get a sound when you receive a message, when you unlock it, when you type a message and when you send a message. It’s just so pointless and annoying.

For most TV's you can turn the LED off (at least my experience with LG and Samsung TV's). It's usually hidden somewhere deep in the settings menu.

I will need to check that out, thanks for the tip. But honestly who even thought that was a good idea in the design?

My personal worst example is my Rabbit Air HEPA filter. This device is very likely to be used in a bedroom at night, especially in spring - and yet it has an always-on display of bright green and blue LEDs. I've had to completely cover the display with electrical tape.

Yeah, we've got a humidifier like that, useful in wintertime but with a crazy-bright LED numeric display and several different colors of lit buttons. Christmas trees aren't as bright as this stupid thing.

On the other hand, a HUGE shout-out to iHome's line of smartphone-saavy alarm clocks. The big snooze bar also acts as a multi-level dimmer, with complete 100% OFF as one of the levels. These have started to become popular in hotels, meaning I'm no longer That Guy who unplugs the alarm clock, stuffs it under pillows, etc.

LEDs just got more and more efficient. Even driving them with tiny currents produces bright light nowadays. I suspect once the efficiency increases stop, manufacturers will adapt and their engineers settle on limiting resistor values that are actually appropriate.

Blue LEDs are basically inappropriate for any purpose where they might be on at night. Making them dimmer doesn't fix the basic problem.

Use an orange or red light instead.

As a Red/Green color blind person I LOVE blue leds. They have mostly replaced the stupid Red/Green off/on indicator that I can't tell the difference between.

Now if only stop lights changed to "blue means go" we would live in a sane world. Picking two colors to mean opposite things (in life and death situations) that 5% of men can't tell the difference between is just a bit silly.

A simple solution for traffic lights would be to change the shape of stop lights to an octagon (matching the stop sign). This would be easy now they aren't a single bulb. Could also change the amber light to a triangle.

Emergency, Fire and Police flashers are mostly blue by convention. Fire, not as much, unless volunteer.

Beyond that, I've always found green lights to be fundamentally, much brighter than any red lights. Tail lights and traffic lights don't shine through bedroom windows nearly as much as when traffic lights turn green. You can see the same effect in black and white photography, but then again, not all traffic systems are the same intensity.

I have a high powered LED flashlight, with a red low-light option, and I find the red LED nearly unusable. I think red, though, is usually a dimmer color than green, when it comes to lighting in the additive color model, and lighting elements.

It's reflective colors that present much less distinguishable differences.

The human eye is more sensitive to green light, so it's not a case of red being dimmer, it's just how your eyes see them.

Traffic light manufacturers are shifting more to the blue end of the spectrum on the "go" light for this very reason.

I've noticed that myself (especially if there's a gas station nearby with a green-LED price sign). The green traffic light is, at least to my eyes, noticeably blue-green/aquamarine, where the gas station sign is emerald green.

Or, you know, you can just PWM them rather than having them going at full blast.

PWM resources can be quite scarce or overkill for a constant brightness level, just pick the right current limiting resistor, it's embedded design 101. Heck, it's your first-year electrical engineering class.

It's not hard to PWM by hand; it takes next to no resources.

Current limiting resistors don't really do great at lower strength; LEDs have far from linear responses and it's very constrained at the lower end that you want.

Source: wrote embedded firmware for close to a decade.

Thanks for that! I'll keep that in mind. I'm largely self-taught in embedded. Curious what you mean by PWM by hand.

> Curious what you mean by PWM by hand.

Have a timer that is some function of your PWM frequency, and manually toggle the GPIO line in the timer interrupt.

You can do it in a super loop too if you don't care about power consumption.

You don't need a whole pwm for a constant brightness reduction. The pulse width never has to change, which is the main feature of pwms.

which another large chunk of manufacturers messes up by choosing to low a frequency and not adding a filter, so now you see the flicker as soon as your eyes move...

Sure, you can screw up any scheme, regardless of how easy it is to do right.

LEDs just got more and more efficient. Even driving them with tiny currents produces bright light nowadays.

Yes. A flashlight today is one chip LED and a "do not stare into beam" warning.

So... there's these great things called data sheets, and they tell you how much current to run through your LED to yield a specific brightness level. Then you throw it into this bad boy here for instance [1]. You still have to do this to validate your design for every part picked.

It's like saying CPUs are getting more efficient, you know, so let's just run way too much voltage through them and hope for the best, and when the industry runs out of efficiency gains we can revisit it. Sure it's hotter than the devils nutsack. It'll be fine.

Efficiency gains are totally irrelevant to this conversation. It's designers who didn't read their data sheets, didn't care, or only tested their product in bright light. No excuse.

For an example datasheet check out [2], the luminous intensity vs. forward current graph is on page 7.

[1] http://led.linear1.org/1led.wiz

[2] http://www1.futureelectronics.com/doc/EVERLIGHT%C2%A0/334-15...

Interestingly, when manipulating a led strip you can see light produced by voltage differences between your hands.

I put a few layers of blue painter's tape over it. Works great. That way, you can still see the blinking indicators, but the intensity of the light is greatly diminished.

And you can peel it off, years later, without any sticky residue either.

You can mostly block blue LEDs by coloring over them with permanent marker, if you don’t want to physically disassemble the device.

Electrical tape is my go-to. Complete blockage and is made to stick to plastic and metal.

I'm surprised it worked for you. I have an Asus N66W router with 5 blindingly bright blue LEDs. Being in my bedroom, it made it really hard to sleep.

Placing three layers of electrical tape didn't work, the light still passed, although significantly dimmed, through the tape. Also, because the router's case is thin plastic, most of the light leakage was through the case. The only solution was to put a pillow over the entire thing. But in the morning the router had overheated and didn't work until resetting it.

Nowadays I just unplug the router before going to sleep. It's driving me insane.

I suggest metal foil under easily removable adhesive tape (e.g. paper masking tape, which is also available in suitably wide formats).

Your electrical tape could be tough and insulating, but it's still basically transparent plastic.

Although it's not an issue as it lives in a cupboard, my ASUS RT-AC68U has a switch on the back which completely disables all of the LEDs. Also to their credit, even though the LEDs are blue, they're not of the obnoxiously bright variety.

Yup. Sharpies work great. I had to do exactly that to the otherwise-excellent air filter that I keep in my bedroom.

I really like opening it up and putting a sheet of tinfoil over the LED, with a single pin-prick hole.

Already posted in another comment, but these "LightDims" stickers work perfectly for me. They also have different colors to blend in with various cases: http://a.co/7KaPIM2

No affiliation, just recommend them to everyone when I have the chance!

Beaglebone Blacks have annoyingly bright blue LEDs, but I find that a double layer of Kapton tape (a thin, translucent amber plastic tape used in the electronics industry) dims them to an acceptable level.

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