15 Pieces - 20mm Piezo Disc Elements with 4" Leads - Acoustic Pickup - Cigar Box Guitar CBG - Touch Sensor…

These are awesome ... The only thing is that they are a bit small ... for what I was doing they had to be replaced by the larger ones but these work great and also produce good energy. They are like the size of a quarter maybe a little bigger but they are cool/

Not quite what I expected and not quite sure how to interface them to an arduino and/or a raspberry pi. The free ends need to be soldered to something in order to use them since they are twisted wire and not a pin end such as a breadboard wire. I am keeping them in the expectation that I will eventually figure out what to do with them.

the wires are way to short

They all worked. I took a knive and scored one on the white ceramic part into four sections (a "+" shape scratch). Then I soldered wires to each of those four slices of the "pie" and ran that to the X and Y and Z inputs on an old oscilloscope---IT IS NOW A FUNCTIONING SCANNING TUNNELING ELECTRON MICROSCOPE!!!I used it as a speaker instead of as a pickup for other uses too. I connected to a signal/function generator to make it vibrate, for testing sonoluminescence experiment setup.If you vibrate water on both sides of a spherical flask you can trap an air bubble in the center. If you do it just right that air bubble will GLOW in the dark!!!! Pistol Shrimp can do this naturally. I actually got it to work, although I used much LARGER piezo transducers as the speakers to output sound--these were just for testing, and for actually monitoring (microphone) some of the parameters for the experiment...just for fun.The photo is my scanning tunneling microscope."Logusz scanning tunneling microscope" and click on the "Science & Optics Blog" and you can see some of the electron microscope, sonoluminescence, etc. stuff.

The wiring is so delicate, more of these have broken than have stayed soldered after installation, in spite of being in a fixed position. They work, until they break, which they will. I'm getting tired of repairing them.

These worked really well for an led project I worked on for my daughter's drum set. I put 4/5 stars only because I wish they had an enclosure with some adhesive like some other piezo elements have.

Nice discs for my 3d printer leveling system and z probe. Well centered ceramic layer. The disc is pretty firm. Not as flexible as some cheaper discs which has made my system more accurate.

I bought these piezos to use as knock type sensors in a Arduino system. My oscilloscope indicated that they produced transients as high as 40 volts.. I ended up putting a 100 ohm resistor in series with the piezo, and a 1/2 meg to one meg resistor in parallel with the piezo, with a 5.1 volt zener diode in parallel with the resistor - and the zener cut negative excursions almost completely out, while positive excursions were clipped at 5 volts. That gave me nicely limited voltages. Sensitivity was cut, but things still worked and the scope didn't show any excursions.