Wiz tells me it's old tech.

New to me. 

Oops.

I blame the new buttons.

Several bands used one until Moog came up with his synthesizer. The Beatles were well known to experiment with just about anything that made sound, as was Pink Floyd. I don't know if they used one on Ummagumma, but I wouldn't doubt it.

Listen to the Theremin on "Good Vibrations" by The Beach Boys, that was one of the first Theremins used in music.

I guess I really am a redneck.  Being from the sticks, I never heard of a theremin until now.

Back in 92 I played around with a schematic for a Theremin that I got from an electronics library book set I bought from Publishers Clearing House. It was a real pita to find all the parts for it. Some of the components, resistors, caps and stuff I already had. It was the copper ball I had a deuce of a time finding. By that time flushometers were being made out of plastic so finding a copper float, old style flushometer, was almost impossible. Took me a couple of months to find one and that in an antique shop. Never did get around to building it. What fascinated me was the no hands on approach. Didn't have to touch it to make noise. Long before that though I had read a few articles about it in the library so dummy me wanted to buy one. I was a lot more ignorant back in those days and I didn't know it wasn't available.

Very cool!

haunting sound it is... nice.