Adrian Bontenbal has provided us with updated notes from his experiments in building a re-creation of Clara Rockmore's theremin. As you'll recall, Bob Moog shared his hand-drawn schematic for Clara's instrument over a decade ago. Adrian started with that schematic and built his own Rockmore theremin! Along the way, he ran into some snags and debugged some component values.
Now, he's back with more updates including a timbre selection circuit and a new tone decoder circuit that shows the player when they're striking a perfect 440Hz tone. This sounds like a very useful feature to me - something I wish more theremins had built-in.
Thanks to Adrian for sharing his work!
Read: Reader Re-Creates Clara Rockmore's Theremin (updated 6/25/2012)