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.

Comments

  1. Chris C. says:

    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.

  2. aztraph says:

    It’s nice to know someone can build it from scratch, but using a microwave transformer is way over kill

  3. L7 says:

    Anyone know how much high voltage that crystal can tolerate before it shatters into shrapnel ?

    • Chris C. says:

      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. ;)

  4. echodelta says:

    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.

  5. biozz says:

    the way i turn off my alarm is a swift smack to the top of the alarm … i know that i would easily touch the XFR and get one hell of a shock XD

  6. Mr Midnight says:

    @Biozz

    Actually was thinking it would be funny if the inventor would get a girl to sleep over…

  7. bothersaidpooh says:

    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..

  8. bothersaidpooh says:

    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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