Some more reference data:
There is some interesting data on the Tannerin, theremin and other stuff in the book Electronic and Experimental Music And the Google "look inside" link given <- reveals pages 49 to 62 which covers the whole topic lightly. (in fact, I found the preceding and following pages enthralling and informative, covering a lot of topics related to ribbon and fingerboards as well)
To emulate the original Tannerin sound, I believe one only wants a pure audio sine wave, as this instrument was based (I believe) on a Heathkit audio signal generator which only outputs a sine wave of quite high purity. The Tannerin is not a theremin of any kind, and does not produce its sound from heterodyning.
Im a little bothered by this - Wondering if my instrument needs to have the option to output a high purity non-heterodyne produced sine wave in order to have the option of sounding like a Tannerin.. Still not 100% sure whether heterodyning adds something I cant see on my kit, but still sometimes feel is there..
Yeah, I know.. the above goes against everything I said earlier in reply to Peter, LOL.. But I cant help it - I am sure that everything about theremins can be scientifically observed given the right equipment - but only 99.999% sure ;-)
Fred.