For the technically inclined, the article also features a look inside the inner workings of a vacuum tube.
On a side note, the article mentions that the theremin remains "mostly obscure". This reminds me of the "mostly harmess" rating given to the planet Earth in the book "The Hitchiker's Guide to the Galaxy". I'm dreaming of the day when world theremization has spread to the point that people no longer think of the theremin as an obscure instrument.
