Auto dimmer hacked into keyboard backlight


As the title says, [José Faria] added the ability to adjust his keyboard backlight based on ambient light levels. But that’s just one of the things he did during his hacking extravaganza with this Razer BlackWidow Ultimate.

When he first received the peripheral he didn’t like the blue LEDs used as backlights. So he removed all of them and put in white ones. He doesn’t talk too much about that but we’d image it was a ton of work. The new color was pleasing, but then the ability to adjust their brightness started to irritate him. There are four predefined levels and that’s all you get. Even the GUI which has a slider for adjustment couldn’t go outside of those levels.

His solution was to augment the controller with his own. He patched in an AVR chip to the transistor which controls the low side of the LED circuits. While at it he also noticed that the keyboard case was actually translucent. This let him hide a photosensor inside which automatically adjusts the light levels. But he did it in a way that still allows him to use the original functionality with the flip of a switch. See for yourself after the break.


  1. josh says:

    I just got rid of mine this week! The room I do a lot of computing in gets kinda of dark at night. With the keyboard even at the lowest level, it brightened up the room so it was hard to get any work done with the “lamp” shining in my face.

    It did have the nice “clicky” feel to it like the old type M. Even that got to be too loud for the kids and wife at night.

  2. vonskippy says:

    Might want to have a professional look into your OCD when you spend that much time on the color and intensity of a KEYBOARD BACKLIGHT.

    • Praxis says:

      “Someone enjoys doing something that I don’t, they obviously must have something wrong with them.”

    • XOIIO says:

      Might want to go to a different site if you make stupid comments like that.

      This is about modifying/improving something, not OCD, it’s hacking because you can, it’s something you enjoy, and it’s something that hasn’t been done before.

    • Exit151 says:

      It’s funny that you say that, because I’m typing this on a Sony Vaio that does happen to contain this EXACT same feature. Why is that funny? Well, for one, this feature is not standard faire on desktop keyboards, and while I don’t know the guy or gal whose work went into designing this system for Sony, I’ll bet he’s more wealthy that most of us now. Kudos for this hack I say, I’m all in favor of adding an automated system to my backlit keyboard and found this really cool.

  3. truthspew says:

    All these lit up keyboards – I don’t even need to see the keyboard. As long as you give me a little reference like the bumps on the F and J keys there’s no need to look at the thing.

  4. rasz says:

    I really wanted to have a keyboard with lit up keys … until I got one :/
    Now I have normal keyboard and LED strip glued under my monitor shelf

  5. brian says:

    Now that’s a hack!! Good job to José.

  6. SYNTRONIKS says:

    I wish it wasn’t so expensive. I bought the blackwidow MAC version to use on PC. I won’t detail my hacking adventure but it works alright! And for $64 for a pro mechanical keyboard, sure. Right on for hacking an Atmel chip in there. I would love some backlights!!! (My circuit board has the thru-holes for it, just only one populated LED for the Razer logo.)

  7. strider_mt2k says:

    Nice hack!
    My Logitech G11 has a three level brightness control built in, so it never occurred to me to need an auto adjuster, but seeds have been planted!

  8. TehMeh says:

    He could have saved himself a lot of effort by just depositing a glow-in-the-dark phosphor over his blue LEDs to make them white.

    • cocasdaneve says:

      I never saw that on sale, where can I get it? Isn’t it hard to apply a uniform coating?

      • NewCommentor1283 says:

        it stopped being on sale when people switched to LCD … ;)
        picture tube + hammer = phosphor

        PPS: (high vaccum) picture tubes are dangerous and can kill you

        • cocasdaneve says:

          Oh, that never crossed my mind, that’s not a bad idea…

          It did took me around 2 or 3 hours to replace the LEDs, but scraping phosphors from a nasty CRT, finding a binding agent and then applying it in all the LEDs is not my idea of “could have saved himself a lot of effort” :)

          Besides, I did this because I am a bit pedantic regarding lighting colors, wouldn’t it be hard to get the proper mix of phosphors and then making it uniform? White LEDs are really cheap on eBay in 100 pcs packets.

          • cutandpaste says:

            Hammer, leather work gloves, dust mask, plastic scraper, compressed air, large paper funnel, clear nail polish, calm wind.

            Stand beside it, and break the neck, just a little. Wait for the vacuum to disappear. Smash the front off. Shake it and/or blow it off to remove broken glass. Lay it on the ground, face-down. Remove shadow mask if still attached. Apply plastic scraper. Make a pile. Funnel it into your nail polish bottle using gravity. Shake vigorously before application.

            …though frankly, I’d probably forego the dust mask and safety glasses and break the whole neck off at once, just because I like things that implode.

    • notme says:

      I never saw the usefulness of a backlit keyboard until I got a desktop computer with a big monitor. I found that the brightness of the monitor murdered my night vision, meaning that I wouldn’t be able to see my keyboard until my eyes adjusted (which is not useful when you’ve got to make quick actions in whatever game you’re playing). Have a logitech K800, which I like very much. That said, I despise blue LEDS in consumer electronics. They make me feel like I’ve got a migraine.

      • NewCommentor1283 says:

        the “headache” is because the pure-blue aka “royal blue”
        is harmful to your eyes when in darkness.
        the pain is caused by (i think) a swelling in the eyeball.
        as a result, eye damage(wear?) can occur

        blue LEDs are often classed as class one eye injury hazard
        you never see that for green or red LEDs

        PS: im NOT talking about “LASER class 1″… im talking about “LIGHT class 1″…

        • cocasdaneve says:

          Blue light is generally bad for contrast, I believe that’s the reason most sunglasses filter blue out.

          I don’t think low intensity blue LEDs are harmful, though. The unpleasant sensation is probably just a bit of eyestrain from the low contrast. The same eyestrain would probably happen if you read blue text on a black background on your monitor.

          • NewCommentor1283 says:

            ive done WAYYYYYY too much staring into BRIGHT,
            FOCUSED blue light that is flashing…
            all the while TRYING in vain to adjust flashing circuits
            to sync to the red and green circuits… causes a lasting migraine.
            stareing from 6 inches away for 12 hours and youll be in pain for another 12 hours afterward.

            i ended up realising i could put a sheet of paper between
            (during adjusting/testing) and not get hurt at all

            im fast with circuits but slow with common sense!

          • NewCommentor1283 says:

            PS sync was the wrong word
            PPS some but not all blue LEDs have warnings on the static bags they come with.
            depends on viewing angle and brightness

          • cutandpaste says:


            3M red vinyl electrical tape FTW. Lets enough blue through to allow the indicator to be clearly seen, while completely killing the brightness of it. Removable later.

            If the lights are big, a red-ish gel filter (Ebay or a local pro audio/lighting shop) will work also.

            I have 3M tape on the ridiculously bright blue power LED on one of the LCD monitors on my desk. (the other monitor was rather a lot more expensive, and allows me to change the color from eye-burning blue to amber or green and dial down the intensity using OSD controls.)

            Or, you know: If you’re adjusting circuit-level stuff for future production, just put a resistor in series with it. Seriously. ;)

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