Here it is in action.
This is what happens when you hook up a speaker to the output going to the tube and let it feed back to the input piezo pickup.
Here's what happens when you talk at it. Although its not quite as sensitive to voice once it's put together, because the pickup is *almost* in contact with whatever it's set on. But you can tilt the whole thing back and it works pretty well.
And of course any time I see an electron beam I just *have* to bust out the magnets.