We Ruined Status LEDs; Here’s Why That Needs To Change

Ah, the humble status LED. Just about every piece of home electronics, every circuit module, and anything else that draws current seems to have one. In the days of yore, a humble indicator gave a subtle glow from behind a panel, and this was fine. Then the 1990s happened, and everything got much much worse.

It’s Not The Technology, It’s How You Use It

With great brightness, comes great responsibility.

The 1990s brought us much good: Nirvana, Linux, and of course the blue LED. Much like “Teen Spirit”, the latter quickly fell into overuse: the technology rapidly became the sigil of all that was new and great, much to the ocular pain of the buying public.

This decision ranks up there for stupidity with other such questionable choices as hiring a rental car at the airport, or invading Russia in the winter. A status LED, most would agree, is there to indicate status. It need only deliver enough light to be seen when observed by a querying eye. What it need not do is glow with the intensity of a dying star, or illuminate an entire room for that matter. But, in the desperate attempts of product designers to appear on the cutting edge, the new, brighter LED triumphed over all in these applications.

The pain this causes to the user is manifold. The number of electronic devices in the home has proliferated in past decades, the vast majority of which each have their own status LED. Worse, many of these are used in the bedroom, be it laptops, phone chargers, televisions, or others. With the increased brightness of these indicators, many of which are on all the time, the average sleeping space is lit like a Christmas tree.

This Samsung charger, designed to be used on a nightstand, was so bright that users hacked it to be dimmer. Image credit: VIPvog, Youtube

The fad of using blue LEDs for power indicators only makes this problem worse. The human eye features special receptors sensitive to blue light that are not only used for vision.These cells are also used to detect the blue light from the sky, coordinating our internal Circadian rhythms to the Earth’s day/night cycle. Exposure to artificial blue light can interfere with this system, with research suggesting it may have a negative effect on sleep cycles.

Part of the problem is that the majority of LEDs on the market now are efficient, high brightness designs. These parts get included in designs with little regard for their excessive light output simply because it’s easy to do so, or maybe the designers have just failed to update their standard resistor value choices.

The fact is, if I can see a bright glow on the ceiling because I left Caps Lock on before retiring for bed, that’s a problem. The same goes for phone chargers and laptop chargers too. I shouldn’t have to wrap a device in several layers of electrical tape to hide a light that should be little more than a dim glow to begin with. If the device is reliable enough, I probably don’t need to be looking at it anyway!

Doing It Right

Of course, we love blinkenlights, and good status LEDs do serve a purpose. They tell us that we’re composing an highly aggressive email with the scary big letters, that our charger is indeed receiving delicious AC current, or that our monitor is receiving power but isn’t really, properly turned on (okay seriously, who cares?). Crucial as they are, there’s no excuse for getting them so badly wrong. It’s important to lay out a few rules to guide their proper implementation and use.

The Amiga 500, presented here as an example of the maximum brightness permitted. Even this is pushing it, though the color chosen avoids interfering with the human body clock.

Excessive brightness should be avoided. As small LEDs can be easily dimmed with a simple resistor value change, there is no excuse for power or standby LEDs that light up a room. Instead, the level should be suited to typical use cases. 1980s home computers had no problems with excessively bright indicators, thus it is suggested that readings be taken from a sample of standard Amiga 500 power LEDs. The average value found should be the upper limit for power indicators on indoor electronic devices. It’s important to remember that you shouldn’t be looking at the power LED that often anyway, unless your hardware is highly unreliable. In that case, you have other problems.

We all agreed, red means record. If it ain’t broke, don’t fix it!

Colors should also be standardised, or at the very least, chosen with some kind of thought as to effective visual communication. While I marvel at the pretty pink LED on Nintendo’s DSi, we had previously long established red as the color of a recording light, and thus there is little reason to differ. If your hardware must have a standby LED (again, really?), make it red or orange. Power LEDs should universally be green. None of this “blue for on” nonsense – it’s just showing off. It wasn’t cool in 2001, and it isn’t cool now.

The purpose of status LEDs should also be questioned. Too many LEDs, or too many colors, can be confusing. A laptop battery charge LED should be a single color, to indicate charging – ideally green. If it’s orange and green, what does that mean, exactly? Charging, and fully charged? Fault, and charging? If a user has to look up a manual to determine the meaning of a status LED, you can likely do better.

The “breathing” animation is less distracting than flashing, but is it really necessary?

Flashing should only be used where absolutely necessary. LEDs for hard drive and network activity should flash, as they indicate a constantly changing state. Mute LEDs on a mixing board should flash, because they’ll save noob techs when they can’t figure out why no sound is coming out. On the other hand, a standby LED on a television should never flash, because if the TV is off, it’s because nobody wants to pay attention to it.

Hopefully, these rules serve as a starting point for hardware designers in future. No longer will a charging pad, designed for a bedside table, bathe an entire room in an eerie blue glow. A TV will not blink incessantly, keeping houseguests awake as they try to sleep on the couch. With a few changes, we may all rest soundly, free from glaring visual distractions as we go about our daily lives. Of course, this is just the opinion of one grizzled engineer. Be sure to sound off in the comments.


259 thoughts on “We Ruined Status LEDs; Here’s Why That Needs To Change

  1. Opinion peices normally leave me something to gripe about but damn, yes you’re right.

    Ok, so my gripe – we need a guide for people like me, utter newbies, on how to modify these lights to be less bright. If it’s soldering on a resistor (after working out the required value) that’s something I could maybe do on a charger or other device that’s not going to kill me (or hurt the wallet too bad if I messed it up).

      1. I have a center punch I just bash into it and sever the LED’s continuity completely. Works in most cases. Some devices want to check that circuit for continuity though. Very, very rarely.

        1. There are certain devices (the only one I can think of off the top of my head is the Commodore DTV joystick) that actually use the power LED in their voltage regulation circuits. It’s a dumbass engineering move, but it still happens.

          1. Being a diode an LED always drops a fairly consistent voltage across it, so if you are powering a low current-daw component you can run a trace to it from “above” and “below” the LED and due to the LED the voltage the low powered part sees will be fairly constant.

          2. Since I can’t reply directly to Mike B, I’ll put it here and hope he reads it:
            This was in response to just punching the LED out. If you remove the LED, it kills the voltage regulation circuit for the entire board.

        1. I haven’t found a decent product of that sort in Canada yet, was familiar with Blu-Tack and cheaper variants, but the only stuff I’ve come across here is nasty. It would be preferable to use random chewing gum one has found on the sidewalk.

          1. Well, to be honest I use ‘häftmassa’ as that’s what it’s called here in Sweden. I had to google what it was called in imperial units :) I have no idea if it’s really an equivalent.

      2. The real oldschool way to do it, would be to darken with soot from a candle or lighter flame. Back in the day that was how you’d get your various shades of darkened glass for whatever lab purposes.

      3. Yes, I have used all of these methods myself, many times. About two years ago, while on the job, the captain of the ship asked me to use nail polish on a particularly bright LED on a piece of Bridge equipment. This is a problem, as it ruins your night vision. You’d think the manufacturer whould know this.

          1. “Hey George you specified a 1 lumen LED on this, you think that will be bright enough?”
            “Should be fine Dave, but if you wanna bang it up to 50 or so just to be sure…”

      4. This. I bought a set of Volta magnetic cables for my wife and I. The phone end has a VERY bright blue LED in it. Bright enough that one cable emits enough light to illuminate a good portion of the bedroom at night. I took a piece of 1/2″ 3:1 black heat shrink tube and put it on that end. No more light.

      5. I’ve been using a hole punch to cut circles of black electrical tape. The little tape disk doesn’t look so ghetto as a random piece of torn off tape. IF I need to see the LED then I might put a needle hole in it.

        1. Yep, I do the same. Place a strip on tape onto the a backing sheet from a sticker. Then hole punch out circles of various tapes, opaque or color tape to match LED’s color to dim. Personally I hate blue led status indicators, my color of choice is amber/yellow/orange.

        2. I’m going to do this today to the Smart TV in my bedroom; Not only did they give it a bright blue standby LED, it often does software updates at about 2am and it lets you know by blinking the LED on and off throughout the process!

        1. I built a countdown timer for a piece of lab equipment which needs its fluid changed every two weeks. I deliberately made the gratuitously overused LED’s on the front blink at different (not common multiple) rates for this very reason! :)

    1. I use liquid whiteout, usually a drop will sit nicely in the indent where the LED is, and when it dries I just sharpie it black.
      It greatly diffuses and dims the light so it is still visible when on, but I can easily ignore it at night.

      I did this to a few home theater devices (Looking at you HDMI switch) that have LED’s bright enough to replace the headlights on my car.

    2. I often actually take items apart, then place the matte/frosted Scotch tape on them in a FEW LAYERS, then put the housing back on.

      This both slightly dims them, as well as diffuses the color.

      For things I do not want to take apart, a company sells these stickers called “lights dims” in both total blackout, and a semi transparent (think like a sunglass lense) sticker that does a decent job dimming the thing while still letting you see that it is on.

      1. The new leds are crazy efficient. Even at 5ma forward current they are way too bright. I have had to go in and change my led values several times on projects to get the light down to a tolerable level.

        Kapton works great on blue leds.

    3. IF there is room for a resistor, that would work. Increasing the resistance will decrease the current through the circuit by Ohm’s law. There probably isn’t the room though, hence the physical hacks.

      1. LEDs will already have a current limiting resistor in series with them that sets their brightness level. Change that resistor to a larger value to make the LED dimmer. Many problems exist that could make this challenging. Sometimes, getting the device open to modify it without visibly damaging it is a challenge itself.
        Other times the extremely small surface mount resistors used to set the brightness level are difficult to unsolder and replace. Thus the masking tape / Sharpie / Postit Note / etc hacks. Something the article missed is why are bright LED displays not dimmed according to ambient light levels? Ever been blinded by LED traffic lights in an intersection? They need to be bright in daylight, but can and should be much dimmer at night. But are they? Not so much, This can and should also be done with status LEDs. A photoresistor can detect the ambient light level and reduce the LEDs brightness level when it is being used in a dark environment. Increased cost to manufacture, yes. Better for users, yes.

      1. Ah, but I notice you don’t say ” only for this purpose”, which to the logical hackaday readership means we’re free to assume all the many other purposes you put it to.
        Not that I want to imagine that thought…urgh!

  2. Indicator lights have really specific and limited uses. Power, record, caps lock, CPU activity on screenless devices.

    When you start getting into things like battery remaining, network activity, etc, I start thinking it would have been way better with an tiny $2 LCD and a button to turn it on/off.

    There’s usually at least one useful bit of info to add that doesn’t need anything but more code.

    Power adapters are the most unreliable part of non-mechanical stuff, and we all accept that even they don’t need indicators, so I really wish people would think twice on them.

    But the worst is multiple fixed color bright LEDs. It looks like such garbage to randomly put blue, green, orange, and yellow in no particular order for supposedly decorative purposes. There’s never any real feeling of design or artistry, just some LEDs that happened to be in the bin.

    Cheap mechanical keyboards do this and it’s terrible.

  3. > The Amiga 500 … Even this is pushing it, though the color chosen avoids interfering with the human body clock.

    Affordable blue diodes started only in late 90’s, amiga started in late 80’s, probably that’s the reason why it didn’t sport blue diodes.

      1. The whole reason blue diodes were a thing is because they were a sign of quality because they were marginally more expensive and exotic than the red and amber we’d had since the 1970’s. Commodore would never have touched that.

  4. Once I’ve bought plant soil monitor. It shall blink red when soil is dry to remind me to water it up. I can’t get around my head why they designed it so it blinks green once a minute. I could not stand it blinking while I watched a horror movie at night or trying to go asleep.

        1. In a way rhe open source chirp! plant moisture sensor does this except it, makes cricket sounds with increasingly shorter intervals. I didn’t get it to work properly though but it might be because I bought a cheap clone from China…

    1. That comes pretty close to the maximum a-hole way to design it. The only remaining sadistic flourishes I could suggest, is that if the green blink is very brief, leaving one in doubt if you actually saw it, or allowing the flick of your gaze briefly away, or natural blinking to miss it completely. Also one could link the soil resistance into the RC timing circuit such that the period between blinks changes, maybe it’s a minute when you just watered it, maybe it’s 3 minutes if it’s getting close to needing some… yeah… with some attention to the details you can make a labor saving device that costs a solid 5 minutes of your time every time you try to save the 10 seconds it takes just to stick your fingers in the soil.

  5. Very good points!

    IEC 60601-1-8 is the standard for alarm systems in electro-medical devices, and it spells out in great detail the colors, blink patterns and sequences alarm indicators should display. Developing devices that comply with this standard has made me carefully consider indicator lights in general. I addition, the usability testing medical device developers are required conduct has also shown me to consider how to accommodate color blind people too.

    Unless I’m working on a standards compliant alarm indicator, I generally use fast blinking red to indicate a fault, solid green for ‘its all good’ and ‘you’re ready to go’, and slow blinking orange/yellow for ‘hold on, I’m not ready’.

    1. Perhaps the best thing in cases of colour blindness is to have each different LED in a different hole with a small piece of text printed into the casing beside it to indicate the meaning. Text, not some silly pictogram only interpretable by the designer and then downscaled so even they can’t recognise it any more.

    2. In my line of work (electrical equipment design for nuclear power plants) colors mean things. In fact there is an entire specialty called Human Factors Engineering that looks at this stuff because human performance is so critical in nuclear power.

      Usually it is consistent with NFPA 79 but not always. Here are some typical usages:
      Green or amber = stop/off/de-energized (safe)
      Amber also used for general indication
      Red or white = run/on/energized (unsafe)
      Blue = clearly we ordered the wrong part

      Indicators are basically never more than one color, and always have text indicating exactly what they mean (eg. “COOLANT PUMP 3B RUNNING”). They’re also almost always solid. Flashing is only used on alarm panels (grids of indicators with text on their faces that flash to indicate new alarms and steady lit after you acknowledge and until you clear it).

      I imagine most operator-action-critical industries, including as you mentioned medical, but also military, aerospace, and industrial machinery (NFPA 79) have their own conventions.

      1. Back at work today, I remembered MIL-STD-1472 “Human Engineering”, which has some very sensible conventions for color coding of indicators. Note that blue is discouraged in general. Also in there are guidelines on brightness, including ability to dim when low-light visibility is needed.

        a. FLASHING RED shall be used only to denote emergency conditions which require operator action to be taken without delay, or to avert impending personnel injury, equipment damage, or both.
        b. RED shall be used to alert an operator that the system or any portion of the system is inoperative, or that a successful mission is not possible until appropriate corrective or override action is taken, e.g., “no-go,” “error,” “failure,” “malfunction.”
        c. YELLOW shall be used to advise an operator that a condition exists which is marginal. YELLOW shall also be used to alert the operator to situations where caution, recheck, or unexpected delay is necessary.
        d. GREEN shall be used to indicate that the monitored equipment is in tolerance or a condition is satisfactory and that it is all right to proceed (e.g., “in-tolerance”, “ready”, “function activated”).
        e. WHITE shall be used to indicate system conditions that do not have “right” or “wrong” implications, such as alternative functions (e.g., Missile No. 1 selected for launch) or transitory conditions (e.g., action or test in progress, function available), provided such indication does not imply success or failure of operations.
        f. BLUE may be used for an advisory light, but preferential use of BLUE should be avoided.

      2. I work on assembling industrial electrical control panels for gas and oil refineries etc.

        We have a particular pump motor starter panel we often make with “RUNNING” (red) and “STOPPED” (green) pilot lights for similar reasons. I also engrave the tags; “RUNNING” makes less and less sense to my brain as I make that tag over and over.

        1. I used to work on old television transmitters.. they would light the button that you were supposed to push next. For example, if the transmitter was on an running, all of the “OFF ” buttons were lit up red meaning that the next thing you would want to do is to turn it off. In the off state, all the green buttons were lit up, meaning the next thing you might want to do is turn it ON. Very confusing and strange way of doing it.

      1. Ideally, they’d sense ambient light and adjust automatically. I know, that means more hardware, but it may be worth it.

        There is no single brightness level that is suitable for use both in a darkened bedroom and outdoors in direct sunlight.

  6. I am a BIG fan of the dim status LED on the laptop power bricks… Plugged in but the laptop isn’t charging, is it the brick? is it the outlet? is it the plug on the computer? With the LED on the brick (Not so much a fan of the ones on the end of the cord although those DO help with finding it in the dark) and I do quite wish more power bricks (whether it’s for a computer or phone charger etc) had some sort of “I’m receiving power” indication.

    I also agree with the some sort of standardization – Green should mean all okay, red should indicate a fault, yellow should indicate standby… For charging status IMO it should either be yellow/orange=charging green=charged… For battery status green should be 75-100%, yellow 25-75%, red <25%, and maybe blinking red = almost dead.

      1. Hah! You haven’t had the misfortune of a dell charger then! Damn thing has a bright white led on the end that not only doesn’t disappear when plugged in, it friggin “breathes” at random times to indicate who the hell knows what. Of course it’s on the emergency response laptop. 1 week in 3 my sleep goes to hell cause some moron thought it would de cool. I would love 2 minutes with that designer and a LART.

  7. That indicator lights shouldn’t be bright is logical.
    That one should at least consider the implied message when picking a color is also a wise thing to do.
    (Though, out of my 5 monitors, only 2 doesn’t use a blue indicator for on…)

    Though, sometimes a far more excessive indicator brightness can be useful, as to convey the message of urgency. Though, preferably in applications where there is actual reason for this. Like informing a person of a critical error. One reason that the “mute” indicator on a lot of audio mixing desks is brighter than the other indicators on the product. (So that one doesn’t need to scratch one’s head about why one channel doesn’t have any sound.)

    Also, unnecessary blinking of an indicator isn’t really helpful.

    1. Yeah, this.

      Mute LEDs on a mixing board should NOT flash. They should be steady. To guide the n00b, there should, if anything, be small mute and solo LEDs close to the control room volume knob, that’s lit if any channel has been muted or solo’d. They are reminders to scan the channels if you’re not hearing what you expect.

  8. some idiots think that superbright flashing bicycle lights was a good idea. perfect for blinding the people coming towards you without actually giving away your position or speed. Oh. shoot, that should have been the other way round. NOT blinding you, showing where you are and at what speed. bummer…

    1. I use a cycle light bright enough to see the road in front of me, and a small, more diffuse, flashing light for alerting the inattentive. I find that combination to be fine when I’m driving and come across a cyclist, it’s helpful to know that the cyclist is a cyclist and is travelling on the road much slower than other vehicles.

  9. Ideally, the LED should adjust its brightness based on ambient conditions. LEDs need to be brighter to indicate status in direct sunlight, barely passing any current at all to be detected at night.

    1. That would be a great one for a howto article, but it might be a little advanced.

      You can use the LED as a photodiode to measure the ambient light periodically, then (assuming you’re using a microcontroller to turn on the LED) you don’t even need any extra hardware.

      It should at least be able to tell the difference between dark, regular, and bright conditions.

  10. I have a bench full of chinese 2way radio chargers (and one Icom) and they have almost standardised the LED.
    Red (or blinking red) means charging, green means fully charged, one goes from red to amber to green.

    Before that I had some who blinked (either red or green) without battery, red when charging and steady green when done.
    One blinked red during charging and steady green when full, steady read was fault.
    Another one blinked red for fault.


    It doesn’t have to be difficult, now I have them all on one powerstrip and kills all of them when not in use, that powerstip has a breaker that lights up red when it’s on/good….

      1. For the same reason my cell phone kindly reminds me to unplug it to save the Earth when it is done charging: It was designed by someone who wasn’t capable of thinking the whole thing through.

  11. My old Yaesu 847 ham radio has blue LED display light, I got a bunch of colour-filters on ebay for it, now it is amber, like my Yaseu 817 and my Yaesu 857, just like god intended it.
    Amber is for me the only colour that doesnt give me eye-fatigue after staring at it for hours… (it’s equal to listen to CQ contest CQ contest and a burst of static for hours and hours….)

    I wonder why old computerscreens were amber/brown or green…

  12. In the section “Doing it Right” the author does it wrong…

    “If your hardware must have a standby LED (again, really?), make it red or orange. Power LEDs should universally be green. None of this “blue for on” nonsense”

    This opinion (presented as the “right” method) ignores the reality that red/green colorblindness is a thing. Using red for standby and green for power prevents these people from identifying the current device status. Sorry, but blue is a better choice than green.

    1. But blue is for bluetooth and wifi being on.

      That said, my bluetooth earpiece has a 10 mAh battery and an indicator LED that draws 1 mA. I just doubled the playing time by clipping the trace to the status LED.

    2. And as far as blue green color blind people are concerned, there isn’t a difference here.

      But yes, using blue for on has some advantages if one uses red for off. Since red green color blindness is the most common variant.

      Though, some products instead blink to indicate standby/off, as to not need a second LED.

      1. Like my coffee maker: It has a few LEDs and a red one in the power button which blinks when in standby/off. Completely annoying! I do not even know, what else it is doing. When “on” a few green LEDs light – thats OK.

    3. Implied here, is they should use DIFFERENT LEDs, that are PHYSICALLY separate, to shine those colours.

      If it’s a single multi-colour LED, then anyone who is colourblind is stuffed identifying what that LED is trying to say. At least with multiple LEDs, it can be determined through position.

      There’s a reason why traffic lights never went to multi-colour LEDs in a single bezel.

  13. One must also consider various laws/regulations on what colors represent. Seems like some jurisdictions have stated that you can’t use a red LED on a device unless it only lights when there’s an actual dangerous condition.

    1. Is it against the law to turn on the red pixels on an OLED display? What if I make my own display out of discrete LEDs, can I use red ones? If I make a device to test red LED’s, how can I use it legally?

  14. Blue LEDs are particularly obnoxious in the bedroom. I use a piece of cloth bandage that I’ve blackened with a felt marker. Does a super job of dimming it down enough to not disturb, without blanking it.

  15. I bought a couple of 4 port USB chargers for my wife and I to take on a trip a couple years ago. The blue LED “status” lights on them are bright enough to use for reading in bed. Electrical tape enabled us to sleep with them in the room.

    1. Ridiculous how manufacturers opt for bright LEDs, a bright LED has more current flowing through it than a dim one, if they put a bigger resistor in series they’d decrease power consumption, maybe not by much for the device when operating but in standby mode the LED will probably be responsible for most of the devices power draw so diminishing nit could helpo efficiency at those times.

  16. Thumbs up! I have dimmed or cut a few of such indicators. One more stupid idea not mentioned in the article is using narrow angle bright leds – viewed from side they are barely (in sunlight) or normally visible but from front they are burning brown tracks in my eyes

    1. How have all these manufacturers forgotten how to add diffusers? Anything fairly opqaue or translucent helps turn a bright pinprick into a spread-out glow. And for manufacturers to be so stupid as to then to pay extra, not much in bulk quanitities but nonetheless more than for normal angle LEDs, for specialised narrow angle LEDs which make the problem worse is obscene.

  17. Ah just remembered the first device I encountered an obnoxiously bright LED on, the Sega GameGear it’s red but it’s damn bright, distracting from the game. That one got black insulating tape on with a tiny pinhole.

    1. I’ve found that severely bright blue LEDs often benefit from a layer of cardboard stuck over them before the insulating tape is applied. No pin holes and even then its still too bright.

          1. Sounds like you need “troubles tree”. to keep the parable short. At the end of the day, on hangs their trouble on the tree, so you can pick them up the next day, if they are still there, in many cases the aren’t there. That has to be much better, than risking a blown gasket

        1. Or if your blue backlit keyboard has a habit of randomly switching on the backlight when the PC is off. Mine especially does this when I plug my phone into the charger which is on the same powerstrip as the PC, though I cant fathom as to how

  18. A low-tech solution: Buy a roll of 80% window tint from an auto supply store (around $10). Cut out a neat square the size(s) you need and apply over the offending display or indicator. (Yes, I said “display,” as in clock radio or microwave oven.) Carefully use a blade to get the backing off and apply. You will have bubbles under there, but the brightness will now be decent! If applied neatly, the film will be unnoticeable on the device. Keep the roll handy, as you will need it when you acquire new tech!

    1. That’s a good idea. It cuts the blue in particular. I have a feeling though that window tints will be changing soon either voluntarily or through regulation. So might have to seek out older stock in the future. So here’s the thing, LED streetlighting is becoming more and more common, replacing the old high pressure sodium. LED streetlights are high power blue with a phosphor to make white. Sodium were very yellow/orange in hue. Now the factory tint on one of my vehicles, under sodium lights, inside the car, you barely knew you had a tint at night, you could see pretty well through it. However, under the LED street lights, it’s almost pitch black. You can see where the lights are, but the incident light off anything isn’t bright enough to see anything by the time it’s gone through the tint. I have to tap my brake pedal a lot while backing up to see anything behind me. Anyway, the change in the lighting has made it go from an effective 10 or 15% at night to a 95% Not sure what the daylight spec is, but it’s pretty dark. I would imagine that by the time LED lights get to be universally used, there will be some changes in tints.

      I’m actually pondering putting on not just a reverse cam, but a left and right looking rear quarter cam, cars are getting LED and very blue HID lights these days too, and in a situation where I have to back out onto a road, I’m worried that looking over my right shoulder (LHD) through the car, through one of the rear tinted windows, I am not going to see some cars, bikes or e-bikes very easily at night.

  19. This, so very much this. I had to replace the resistors for the LEDs on the NTP-dongle for my nixie-clock, because the room was brightly lit at night. People still choose resistor values as if it was still 1978 when you had to pump 20mA through an LED to make it visible at all. With todays LEDs you barely need 1mA for indicator purposes.
    Regarding colors: I wish all indicators were a pretty color temperature orange, the color of a cozy camp fire, or a nixie clock. It’s also the color of a dimmed down incandescent lamp, perfect to get sleepy in the evening. If they all used amber LEDs, we would not have this cacophony of different colors emanating from 20 different gadgets in our rooms.

    1. Well some of it could be voodoo design, y’all seent this on Q&A sites “What resistor I need, how many ohm for drive LED?? Tell me now, I pay for internet” and somebody might say 330, while everyone else tells him to get stuffed.

    2. But LEDs are still spec’d for (at) 20mA :-) So you can if you want :-)
      Although I have observed blue LEDs which (dimmly) lit up with the resistance of my finger in series (at about 12V) started to be visible at 100nA.

  20. I have a pair of USB headphones that are festooned with blue LEDs. I can’t switch them off and they are too damn bright. Can’t Kapton them because headphones have a year of warranty left…

    For power indicator light I usually use either red, yellow or amber LED. Amber is the best IMHO. Puts me right into neon mood. My next mains-powered project might use genuine neon indicator, just for fun…

    1. Same here,

      I wanted to listen to some podcats in bed, but the blinking blue led on the side of the cans lights the whole room up keeping the missus awake.
      Black gaffer tape worked in the end.

      It has a red led to indicate it is charging. ????

      1. Yup. And that red LED is not as bright as the blue abomination. I hate blue LEDs in consumer electronics – they are tacky as hell. And some people use them in their DIY projects. Set ofcourse to full brightness…

  21. Excessive brightness and agree blue overused. Blue has its use as a ‘situaton’ indicator. Red has been a power on indicator for a very long time. Should be as bright as its ancient neon predecessors. NE bulbs also used with CDS photo cells were the first cheap optocoupler. Long life and cheap. Ye ol neon had a purpose also as a voltage indicator in polarity and AC. Gentle 60hz ‘hum’ red appearance in AC use sort of warm; inviting.
    Do miss the beautiful green glow of ‘magic eye’ tubes. So hard to find. Ha.

      1. They were used in a lot of things. Battery chargers, FM locks, SWR meters, audio peak levels, and so on. Was very much a featured item. Some had very specific gradients /segments. Like first generation bar graph display. In vacuum tube form. Green glow was just awesome when your radio blinked at you. Even saw a couple in a 60s animatronic (mostly mechanical) robot head for eyes. Very cool.

  22. It’s not just status lights, it’s backlights too. I got a Logitech G610 keyboard because I wanted a keyboard that wasn’t completely dark at night. It only has white LEDs, but they are really bright. They’re so bright that out of the four selectable brightness levels, only the lowest is tolerable to me in the daytime. I only need to see which key is which, not to use the keyboard as a book light.
    It also has a big lit-up Logitech “G” logo in the corner for no good reason, and very bright num/caps/scroll lock LEDs. I put a small piece of black gaffer tape over the logo, and another over all but a hair of the num lock LED, just enough to notice when it isn’t on.

      1. Possible. But you can not take your own car with you in the plane. So renting a vehicle is the only option.(If you stay longer than a day and do not want to pay extreme amounts for taxis.)

      2. When I rented from Hertz in Nashville (~10 years ago).
        I had planned on topping off the tank on the way to the airport before turning it in.
        I did not see ANY gas stations on the drive to the airport!
        So I turned it in 4 gallons low.
        Hertz charged me $9.99 a gallon to fill it up!

  23. It’s worth noting that the power LED in the Amiga 500 (and other Amiga models) performed three other functions. It had a half brightness mode that indicated when the audio filter was disabled. The Amiga also indicated when it crashed by pulsing this filter on and off, resulting in the power LED flashing dim/bright. Finally, when first turned on, the light would be dim, then going to full brightness when the CPU started running the boot code. Absence of this brightness change indicates a hardware failure. Very early versions of the A500 had a red power LED which was off instead of dim, so a crash had the power LED flashing on/off instead of bright/dim.

  24. What I thought was very stupid was when the activity LEDs for floppy drives were changed from Red to Green. ISTR a few early high density 1.2M drives with a red LED but every 1.44M drive I’ve seen has a green LED. Some early CD burners had a proper red LED to indicate when they were recording.

    What is extremely annoying are devices that turn themselves on when plugged in, or when they’re unpligged. The BlueTooth three way card reader (RFID, mag strip, chip) I have for PayPal does that. Plug it in to get it charged and the damn thing turns on and boots up. Turn it off when plugged in so it’ll charge faster, then when uplugged it turns itself on and boots up. Booting up takes a couple of minutes! Thus I cannot simply plug it in to charge, then unplug it and toss it in a bag when I go somewhere *then* turn it on when *I* am ready. Nope. I’m forced one way or another to waste 2 or three minutes just to ensure the thing is OFF when I’m not using it. The battery will stay up for months when it’s off and only monitoring for a USB connection state change so it can turn itself on.

  25. There’s actually a good argument that poorly chosen indicator colors were a contributing cause to the Three Mile Island disaster.

    The disaster was caused, in large part, by the operators loosing situational awareness due to confusing controls and status lights that were not standardized. For some valves and actuators, the status lights were indicative of mode, i.e. green for normal / red for alternate, for others, the lights were indicative of state, say, green for open, red for closed.

    But sometimes closed (red) is the right state and green (open) can cause a big explosive, mess.

    1. This is different from the TMI event, but it’s commonly misunderstood that the red/run green/stop convention is backwards from what we are used to—red light means stop and green means go.

      But it’s actually completely consistent: red=unsafe; green=safe. From this perspective it’s easy to see that a running fan or pump motor should be indicated with red due to possibility for injury from running machines.

      Another way to look at it: red means that I need to stop, and green means I’m ok to proceed.

      1. I guess the problem here is that in some industrial processes the state of the machine, valve, switch etc. can’t be said to be “safe” or “unsafe”, as it depends on the overall situation. Opening some valve might mean letting out hot steam with nasty chemicals, but keeping it closed might cause pressure buildup and explosion or breakdown somewhere else. What color should be indicating closed status?

        1. Like you said, it’s application specific and impossible to come up with a universal color code which makes sense in all situations. Which is why there are human factors engineers whose only job is to think about these things.

          The best you can do is come up with a set of rules for how these things work in your own plant, based on what minimizes the chance of incorrect operator action, and standardize on it.

          Also nuclear power plants have training centers with entire control rooms with every control and indicator replicated. They run scenarios, train diligently, and make corrections when someone makes a mistake.

      2. The same goes for RCDs, circuit breakers etc. in residential buildings. The ones I have use red for “ON” and green for “OFF” which was confusing for me at first, but makes perfect sense from the point of view of someone touching bare wires.

  26. Another thought on colors – years ago I was in the Smithsonian Air & Space museum, and I went by the Enola Gay exhibit.

    As part of the exhibit, they had the ‘safe’ plugs that were used in the bomb. IIRC, there were three safe plugs that had to be removed and three ‘arm’ plugs that had to be installed.

    They were color coded, and I remember having the classic engineer moment where I got obsessed over the proper color code for the plugs.

    Should green mean ‘safe’ and red mean ‘armed’, in which case red==boom?

    Or should green mean ‘ready to go’ and red mean ‘not ready’ in which case green==boom?

    You would *not* want to get that backwards, but it wasn’t at all obvious, at least to me.

    I could totally imagine one guy setting up the system in a lab in Los Alamos confident in the knowledge that the color code was totally obvious, and shipping a bomb case and two sets of plugs to the South Pacific, where the guys there pick the other option.

    For what it’s worth, I think pale blue is the standard for ‘inert’, so at least we got that.

  27. This article is bang on point. Aside from PCs, keyboards, wifi routers, network switches, Tivo boxes, refrigerators, kids toys and various others, another appliance or fixture which gets my goat is heated towel rails. I go for a pee at 2 am in the morning and my eyes are immediately drawn to the bright blue light on the towel rail which illuminates our whole bathroom at night.

    Modern LED alarm clocks are a travesty of over illumination too (as if that horrible alarm sound used by nearly every cheapo and not so cheapo alarm clock since 1980 was not enough). I’m now using a 70s Sanyo click clack radio alarm clock which is illuminated by a tiny old school bulb. It emits just enough light that I can read the clock at night but not enough to notice if I’m not seeing what the time is. Another bonus is that when I’m reading at night, I can hear the ever so slightly tone of the clock turning over an hour so I know its time to turn off the light at 11:00 pm.

    Now if only I could find the correct sized and rated linear pot to replace the volume control so I can use the radio function…

    1. Perhaps you should connect the towel rail with a timer, so it does not waste energy while you sleep at all.
      My current alarm clock has big amber 7 seg numbers which are dimmed nicely between 23h and 5 in the morning. Before I had one with big blue lit negative LCD numbers. They dimmed with a light sensor, but the contrasts was not very good, so the “black” background transmitted more than enough blue light ´, especially on an angle to disturb some guests.
      Luckily I myself are not that sensitive for light with my sleep. The only thing which is a real No Go is noise. A clock in my bedroom must not have any moving parts, must not tick or clack.

  28. Another aspect is size.
    I recently switched back to through hole LEDs from tiny 0603 single pixels. At least you can see there is an off LED when it is off.

    There is a distinct difference between simple and complex systems. In simple systems you typically want more system information out, In complex systems you want less. In complex systems the predominant problem is data overload.

    For this reason I like the dark cockpit philosophy. Only draw attention to failures. Unfortunately we do need to be reassured that the system is operational, so we need one, just one, green or blue flashing or breathing LED. The activity tells us the CPU is active.

    The Ideal rack of equipment functioning without failures need has one CPU LED per enclosure to be flashing. Any more indicate failures, and these failure LEDs are to be RED.

    At startup, all LEDs turn on for a second or two. This acts as a globe test, to reassure the technician that the LED driver hardware is functioning correctly. And helps detect watchdog timeouts. Unfortunately designing for globe tests sometimes need more pins as it meens not just wiring LEDs across relay coils.

    A clear, consistent, indicator design philosophy, that is the price you pay for being able to debug a system you designed decades ago. Over the phone. From a beach. On the other side of the planet.

    1. There are also opposite examples: My HP keyboard here has so tiny indicator lights: about 0,8mm dim white that you have to shade it with your hand from daylight to see if CAPS LOCK IS ACTIVE.

      1. And Apple does the opposite thing as well. No indication lights on their Macbooks. Not even one that shows if the storage is being accessed. So if you Mac is hanging, there is no way to see if it’s crashed or just very busy with something.

    2. SAAB, (the fighter jet manufacturer) included in their cars an button called black panel, that turnedd off all lights that wasn’t needed. If something happened, an over temp for exmple, it lit up that meter.

      That’s so brilliantly simple and useful, why hasn’t anyone else adapted to it?

      American cars with red dash lights are the worst, exept bright blue ones

  29. A friend pointed me to something called lithographers tape that is very useful for covering annoying multi-color indicator LEDs. It’s a ruby red translucent tape that filters out all but the red and some orange light from the indicator.

    If you have white LED indicators, they will appear as a deep red. If you have indicators that are blue in certain modes, the blue will be completely blocked. Any modes with a red indication (like a standby mode) will be visible.

    Electrical tape or nail-polish are still cheaper if you just want to block all the light but I’ve found the lithographers tape to be really helpful for several monitors with multi-color LEDs and a room HEPA filter that decided to use both white and blue indicators for some reason.

  30. One of the best articles ever on Hackaday.

    I once bought a rack-mount KVM for a server room management console. It had transparent buttons for each device, with a green and amber LED in each one, LABELED so you could tell what was happening… then came the goddamned POWER LED… the brightest goddamned Blue 3mm LED ever made. I covered it with electrical tape just to block it out… turns out it was bright enough to shine through that and match the intensity of the green LEDs. Without the tape, it just lit up the server room all on its own.

  31. I dislike blue LEDs for another, I believe not yet mentioned reason: blue leds “wander around” when I move my head.

    I _believe_ this is caused by refractive properties of my rather strong glasses. Imagine a small blue number display. When I look at it “crooked”, through edge of glasses, then those blue numbers are perfectly readable, but appear displaced, floating high above their intended position, and do not stay still. Worse than blue are purple leds – instead of single source of purple light I see separated red and blue. For some reason I have no such problem with other colors, greens and reds and yellows stay where they supposed to be.

  32. I really hate the red blinking “OFF” LED of my coffee machine. A red blinking LED in my understanding is a warning sign. Probably the designer just could not leave it constantly on to fulfill some energy savings requirements. But he could, for sure, just turn it off constantly, if the machine is switched off.
    As it is built to illuminate one of these translucent silicone buttons, any method of covering it, would also probably be short lived.

  33. Ah yes, I’ve removed several leds from devices like hygro/thermometers, video streaming devices with piercing blue leds, harddrive enclosures etc. There’s one that I’ve not been able to remove, a charging led for my tablet (huawei mediapad iirc). it’s a piercingly bright led just above the screen when charging, which I do at night. I want to read at night before sleeping but this led was driving me crazy. I just put some black tape over it. While I was at it, I’ve taped the fingerprint scanner as well as it always triggers something at times you don’t want things to trigger. I never use it anyway. Android tablets are getting rarer these days so choosing something else is just a different compromise.

  34. I chopped a chunk of the LED lead in my Samsung Qi charger, I have no need for my charger to tell me it’s sending power to my phone when my phone can tell me that very same thing.

  35. Heh. I have one of those sunrise alarm clocks. They slowly turn on a light to simulate a sunrise, which makes your waking up a little less traumatising.

    So, this alarm clock (not a Philips, by the way, but a rebranded Chinese thing) features an LCD for the clock part.

    But the designers obviously realised that the LCD will not be readable when it’s dark. So they thoughtfully added a backlight to it.

    This backlight has the feature of providing two brightnesses: Stellar class O0 or Stellar class O2 . The backlight itself was brighter than the light that simulates the dawn.

    And they took the unholy decision to use a BLUE backlight! Completely messing up your sleep, and capable of making even the sanest person become psychotic within a few days.

    Why, for God’s sake, why?!!?!

    Of course I hacked it the next day. But still… Why?!?!?!!?

  36. SO IT ISN’T JUST ME AFTER ALL!!!! My house is punctuated with black electrical tape. But I use a single hole punch to make a very satisfying “black hole” that sucks all the light in. If something is off, I want it totally off.

    1. Unfortunately these days we _want_ inefficiency on websites. The longer a user stays on your site looking for the information they are trying to find, the more time they can be served advertising. It sucks.

      1. If I’m convinced the info is there, I don’t bother with the site nav and make it spill it’s guts with google-fu, or if it’s all fluff and no substance, I go somewhere better.

        Also, meet my pet peeve, a raging hatred for craptastic mobile styled sites served to desktop browsers.

  37. Every time I enter my living room in the night (on the way to the kitchen :P), I am startled about the amount of light there is from all of these devies that I have there.

    No wonder my cat always wants to sleep in my bedroom. It’s the only place in the house that’s (close to) dark!

  38. Some routers and switches use PCB mounted LEDs sending light to the outer case via a single shared plastic light pipe. This makes them completely useless as status indicators, as the light from one LED illuminates the entire light pipe. It’s all or nothing. Try handling tech support for these – “Which light is flashing?” “All of them.”

    1. There should be a zero light bleed light pipe for each LED. BIVAR has flexible zero light bleed pipes. Makes me wonder what light pipes are made of, if you can bend them. Fiber optic light guides?

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