Dhruva CD Super

This box is made in India by a company called Radel.  It produces a constant drone that I use for intonation practice (fiddle and voice), improvisation and interval experimentation, and composition.  You can select from the following: 1) single note; 2) perfect 4th; 3) perfect 5th; or 4) one constant note with one or two other tunable/sweepable pitches.  Great fun for parties!