How to test Rochelle salt crystals or piezoelectric crystals. In this case I measure the voltage using an oscilloscope. I also give a few pointers on how to use the oscilloscope. I also show that the crystals have polarity.

See also this video on how to make Rochelle salt crystals:
   • How to make Rochelle salt piezoelectr...  

And here's where I use my large crystal to make a speaker for a radio in my " How to Make Piezoelectric Crystal Speaker" video:
   • How to Make Piezoelectric Crystal Spe...  

And I even press it against a window's glass to make a speaker in my "Piezoelectric Speaker - small crystals/window as speaker" video:
   • Piezoelectric Speaker - small crystal...  

For more see:
http://rimstar.org/materials/piezo/ro...

To see how to make a larger crystal from a seed crystal:
http://www.seawhy.com/xlone.html

For how to get more powerful piezoelectric crystals, see "How to take Piezoelectric Igniter from Lighter fr Spud Gun":
   • How to take Piezoelectric Igniter fro...  

and "How to get Piezoelectric Crystal from BBQ Ignitor/Sparker":
   • How to get Piezoelectric Crystal from...  

http://rimstar.org