The world needs standardized LEDs which adjust brightness

I’m sure, like me, you have lots of electronic gadgets that have status LEDs on them. Some of these just show the thing is on, some blink when it’s doing things. Of late, as blue LEDs have gotten cheap, it has been very common to put disturbingly bright blue LEDs on items.

These become much too bright at night, and can be a serious problem if the device needs to be in a bedroom or hotel room. Which things like laptops, phone and camera chargers and many other devices need to do. I end up putting small pieces of electrical tape over these blue LEDs.

I call upon the factories of Shenzen and elsewhere to produce low cost, standardized status LEDs. These LEDs will come with an included photosensor that measures the light in the room, and adjusts the LED so that it is just visible at that lighting level. Or possibly turns it off in the dark, because do we really need to know that our charger is on after we’ve turned off the lights?

Of course, one challenge is that the light from the LED gets into the photosensor. For most LEDs, the answer is pretty easy — put a filter that blocks out the colour of the LED over the photosensor. If you truly need a white LED, you could make a fancy circuit that turns it off for a few milliseconds every so often (the eye won’t notice that) and measures the ambient light while it’s off. All of this is very simple, and adds minimally to the cost. (In fact, the way you adjust the brightness of an LED is typically to turn it on and off very fast.)

Get these made and make it standard that all our gear uses them for status LEDs. Frankly, I think it would be a good idea even for consumer goods that don’t get into our bedrooms. My TV rooms and computer rooms don’t need to look like Christmas scenes.

You can probably do this

You can probably do this easily enough with a small microcontroller (one of those SOT23-6 chips should work fine) and your choice of LED.
PWM to control the brightness, with sensing of ambient light during the "off" part of the PWM.
Multiplies the cost of the indicator by 10x to 20x, though. (LEDs costing pennies, tiny microcontrollers costing dimes...)
Use of an "off" LED for brightness sensing is pretty well-documented, though I'm not entirely sure that it practically includes the levels of "dark room" vs "somewhat illuminated room at night"

Yes, full microcontroller too expensive

I feel that use of a full microcontroller is the wrong path here. The circuitry needed to do this is super simple, you would barely even call it an IC, and indeed, it has to not add much cost on top of the LED. Apparently you can even use the LED as a photodiode when its off, or have your own phototransistor which would then drive the timer in your PWM. But it’s just a couple of parts, and the idea is to promote the function as important so they get made in the hundreds of millions and don’t cost much more than the bare LED.

Maybe you could get Adafruit

Maybe you could get Adafruit to stock a version? Get the idea into heads of next-generation of designers.

I wonder if the reason they're so bright is that products are competing for attention on the shelf - brightest LED in a brightly lit Best Buy wins. They are never seen in the dark before purchase. Same as how all the TVs on display have brightness & color saturation turned up way too much.

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Post new comment

His name is Brad Templeton. You figure it out.
Please make up a name if you do not wish to give your real one.
The content of this field is kept private and will not be shown publicly.
Personal home pages only. Posts with biz home pages get deleted and search engines ignore all links
  • Allowed HTML tags: <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.

More information about formatting options