A 50W Speaker Made Of Light Bulbs

When we think of a speaker, we are likely to imagine a paper cone with a coil of wire somewhere at the bottom of it suspended in a magnetic field. It’s a hundred-plus-year-old technology that has been nearly perfected. The moving coil is not however the only means of turning an electrical current into a sound. A number of components will make a sound when exposed to audio, including to the surprise of [Eric], the humble incandescent light bulb. He discovered when making an addressable driver for them that he could hear the PWM frequency when they lit up, so he set about harnessing the effect for use as a speaker.

Using an ESP32 board and with a few false starts due to cheap components, he started with MIDI files and ended up with PWM frequencies. It’s an interesting journey into creating multiple PWM channels from an ESP32, and he details some of his problems along the way. The result is the set of singing light bulbs that can be seen in the video below the break, which he freely admits is probably the most awful 50 W speaker that he could have made. That however is not the point of such an experiment, and we applaud him for doing it.

For more MIDI-based tomfoolery, take a look at the PCB Tesla coil.


27 thoughts on “A 50W Speaker Made Of Light Bulbs

    1. I mean audio signals are necessarily AC. Why would it need to be DC? I assume there’s also a 60hz hum that just isn’t manifesting much because of the awful low frequency response of a dang light bulb. It’s a feature, not a bug!

      1. Pulsed DC is AC. It just has a square wave instead of a sinusoidal one. Even if it has an additional DC voltage added to it (2.5v to 5v pulsed DC) you can still run it through a transformer to get the AC out of it(-1.25v to 1.25vAC). Or, 0 to 5v pulsed DC would be -2.5 to 2.5vAC. In other words math is fun.

  1. Heh heh, I wonder if you’d get better sound out of mushroom bulbs, thinking they’d project out the front/top of the bulb better, but also you might be able to explode them by trying too hard (Get them vibrating just right/wrong)

    Now I’ve heard buzzing and singing out of incandescents before, but my Uncle told me he knew someone near an AM transmitter that had to have theirs screwed in really tight, because if they were only lightly on the contact the oxide layer would diode and the AM station could be heard from the bulbs, I thought he was shitting me at the time.

    1. You are making me want to hop in the car with an inverter and an incandescent lamp and turn it on while parked by a local AM radio tower. Still, I’d hate to have to explain to the authorities just what I was doing if they got curious. :-) Perhaps I should take one of them with me since some of them are my friends. :-)

          1. Hey, just like vacuum tubes! A light bulb is kind of a vacuum tube, right? Just a totally passive one. You could make a killing. Just be sure you coat the screw threads and little center contact with gold and platinum or whatever.

  2. You need one of those old car head lights from the 70’s, better yet, a big truck head light, the kind with the whole glass and mirror (not those new insert and twist bulbs). I bet it will give better bass (think woofer).

    1. No. That was never a thing. People freaked out about it and hoarded anyway. Kind of like with guns when people have a gun ban panic. In fact, I bet there’s nearly a 1:1 ratio of people who are gun hoarders also being incandescent hoarders.

      1. You know nothing about gun hoarders. Many of them are also KNOWLEDGE hoarders and know that LEDs are better in a crisis. They actually read stuff and learn rather than watching the boob-tube all the time letting thier brains rot.

    2. My recollection isn’t always the best, but as far as I remember, the laws were never geared towards consumer ownership or usage of such incandescent lighting. They wanted the companies to stop manufacturing them, and figured that as the supplies dwindled and demand skyrocketed, people would naturally migrate to more efficient lighting technology. The same applied to older florescent lighting like the T8 fixtures/tubes, if I remember correctly. Ironically, I don’t recall these laws ever mentioning the higher voltage sodium or mercury vapor lighting commonly used in street lighting, though a lot of municipalities were/are switching to LED to save money regardless.

      The shop where I worked at the time had probably 40 8-foot T8 fixtures in each building, and several mercury vapor lamps outside as security lights, with the last building (used as warehousing, of sorts) using 16 sodium lamps as it’s sole lighting, except for the small office up front. The owner used to go crazy if someone would leave the lights in the warehouse on for more than 5 minutes if nobody was actually in the warehouse..

      1. WalMart sells cool white 4 foot T8 LED tubes in packs of 10 at a price so low they cost little more per tube than T12 or T8 fluorescents. Even better, they’re universal ones that work with magnetic ballasts, found in most T12 fixtures, and electronic ballasts, found in nearly all T8 fixtures. Thus they’re a plug n play job. No need to pay an electrician to modify the fixtures. Power use is marginally higher than for direct wire LED tubes.

        I’ve told several business owners about them and how much electricity *and money* they could save. The LED tubes only use 17 watts. A 4 foot T12 is 40 watts, a 4 foot T8 is 32 watts. Look at the ceiling of some large store and count 200+ 4 foot tubes, that would add up to a huge savings that would quickly pay back the cost of the LEDs. If only WalMart sold an 8 foot version. A local store has over 800 8 foot T8 tubes in their main area. No idea how many they have in the storage, office and other sections. Probably adds up to at least 1,000 tubes.

  3. I once had a non-working Konami Scramble Bootleg board that was watchdogging and I noticed that one of the 8255 emitted sound that matched some of the crap on the data bus. I tried swapping it with different versions from three different manufacturers (Intel, NEC and Matsushita) and they all sounded the same.
    After fixing the game, none of the chips made any noise.

  4. Could one just run some regular audio output from an amplifier at a very high power or maybe through a transformer to match voltage for what the bulbs want? Then you could just throw a record on it.

  5. Remember light organs? They flickered incandescent bulbs that were painted various colors or were behind pieces of colored glass or plastic in some “art” piece that hung on a wall. A microphone and some simple circuitry made them respond to sound.

    Now with this setup a light organ can live up to its name. “My light organ has 16 bulb polyphony!”

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.