Are you thinking of the theremin, perhaps? I believe it is an Etherwave from Moog... The theremin is the earliest electronic instrument, being invented over 80 years ago.
I can't answer the Joe questions for him, but he has up to this point used it in his performance of The Ballad of John Henry, both the studio recording and live. He has used it live also in his Just Got Paid medley...
Rock On & Keep the Faith,
Rocket
"He still doesn't charge for mistakes!
"
http://jbonamassa.com/tour-dates/"Everybody wants ta get inta the act!"
“Now, this isn’t your ordinary party crowd, here. I mean, there are professionals in here.”