One handed theremin?

Hello!

I have a question that I have thought about for a while, so I thought I should come here and ask the experts...
Is it possible to make a one handed theremin?

My thought is that the box between the pitch antenna and the volume loop antenna includes the volume antenna all the way to where the pitch antenna begins. Moving the hand that decide the pitch upwards or downwards would then decide the volume too. A bit tricky perhaps, but that way it would be possible to play two theremins at once. One with the left hand and one with the right hand. :) That would be cool.

So, would it work or do the laws of physics work against my idea?
Im sorry if this topic is already discussed somewhere. I tried searching but couldn't find anything like it...

[b]EDIT:[/b] Btw, im not actually going to build one, Im just curious to know if its possible. Im going to buy a theremin though! I recently found out about the instrument and fell in love with the Celia Sheen plays Midsomer Murders on Theremin (http://www.youtube.com/watch?v=YTZK9FNgK74) youtube clip.

What you suggest is possible, but has several aspects which make it less useful than one would imagine.. "A bit tricky perhaps" is a severe understatement..

First, one would need to carefully design the volume antenna circuit - a standard circuit usually has the problem that it loads the pitch antenna, and therefore vertical hand movement will cause both a pitch and volume change.. It is not easy to overcome this problem.. it happens to some extent with 'normal' theremins but the problem is less noticable because capacitance of each hand to ground is a small proportion of the body's total capacitance to ground.. use a single hand for both pitch and volume and one is effectively sharing a common 'plate' of a capacitor coupled to both pitch and volume circuits - interaction is inevitable.

There are ways to overcome the above - but I have not been able to achieve this with 'conventional' theremin circuits.. and even with my best implementation I still do not believe there is enough accuracy for control of pitch and volume simultaneously... One can get away with minor deviations if dealing with control of volume or harmonics, but we are just too sensitive to pitch variations IMO to tolerate the deviations which result from attempting to control pitch and anything else using a single hand.

Fred.