How to make your own piezoelectric speaker

Piezoelectric speakers are found all around you, from musical greeting cards to the tweeters in your car stereo setup. Making your own piezo speakers is actually very easy, as [Steven] shows us after replacing the speaker in a clock radio.

Piezo speakers require a small crystal with piezoelectric properties, so this build is the perfect followup to [Steven]’s tutorial for making Rochelle salt crystals. After attaching two strips of aluminum foil to his Rochelle salt crystal, [Steven] took the wires that previously went to the clock radio speaker, connected them to the crystal, and turned on the radio. When attached to a tin can, the newly created piezo speaker created a little bit of sound, but the results weren’t very impressive.

To boost the sound output of his homemade speaker, [Steven] needed to increase the voltage across his piezo speaker. At first he tried a doorbell transformer with somewhat better results, but much more sound was produced when he used a transformer taken from a microwave oven.

After experimenting with his microwave transformer and Rochelle salt, [Steven] moved on to piezo elements found in BBQ and cigarette lighters. These homemade speakers were much clearer than the chunk of Rochelle salt he was using previously, and surprisingly produced about the same audio quality as a commercially made piezo speaker [Steven] picked up at Radio Shack.

You can check out the build video for [Steven]’s crystal speaker after the break.

14 thoughts on “How to make your own piezoelectric speaker

  1. If you’re going to throw a microwave oven transformer in the mix, why stop there? Try an electrostatic speaker while you’re at it.

    1. If he had one around the house. But a small audio transformer will do as well, not too expensive. But then it’s not really intended as a speaker system.

      1. A microwave transformer was all I had. But I actually went out and bought the doorbell transformer and tried that first, not knowing about audio transformers at the time.

          1. That depends on where you get your parts. Most of mine came from stuff that was thrown out: food can, rubber band (mail is often wrapped in these, as well as some vegetables), transformer from old microwave oven, piezo crystal from piezo speaker in microwave oven, old alarm clock, aluminum foil from the kitchen, even the wires can come from the microwave oven or other thrown out electronic hardware. I made my own piezo crystal by making Rochelle salt. Due to the high cost of cream tartar, that cost around $20. See here for how to make Rochelle salt:

            or here:

            http://rimstar.org/materials/piezo/how_to_make_rochelle_salt_piezoelectric_crystal.htm

    1. If you make it perfectly anhydrous by first heating the crystal in an oven to drive off moisture, it would take a lot of voltage to punch through it due to its thickness. But from there, as Rochelle salt progressively absorbs moisture from the atmosphere (being deliquescent, it can even do so to the point where it melts into a liquid solution), expect less from it.

      Your average thin piezo element in a tweeter can handle only 25V, maybe a little more. Above that it slowly degrades as a result of the excessive flexure causing cracks, though you might not notice it for a while. At 200V, you will notice it in a few seconds. ;)

  2. Can the salts be set on a large planer surface. That may make some noise.
    The output transformer from a tube era table radio used in reverse would work quite well.

  3. I emailed Jeri and someone else about this a while back, to see if Rochelle salts would work as a cheap way to get X-rays using a sub standard vacuum and a Peltier module.

    Unfortunately Rochelle salts tends to sublimate in a vacuum so unless someone can figure out a workaround (encase it in silicates maybe?) its not going to work.
    LiTaO3 as used in the original experiment is crazy expensive..

  4. I even looked into making barium metal by evaporating it onto a surface but the problem is that with this method it oxidises before all the oxygen is gettered out.
    Turbopumps are much $$$ for a reason, the cheapest I could find without shipping & gouging was $200+ ..

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