I volunteered to help a friends child with her science fair which we decided to do on sound. After seeing the chladni plate displays on YouTube I thought this would be a great display for the project. I assumed you could drive the plate with just a simple speaker but the lower frequences just bounced the salt right off while the higher had to be unbearable loud to even get the salt to move. Overall a regular speaker produced limited results for the loudness you had to deal with.
A lot of people use a piezo but I found this to be to small to produce a good effect. I ran across a website Cymatics
which had a link to a wave driver you could buy and after looking it over I realized it was just a modified speaker which could be easily made for cheap. This is my first instructable.