Question about the oscillators of the EM theremin

Just done a quick frequency response analysis on your modification vs the original EM circuit - above 100kHz  your circuit poses far greater attenuation to the signal than the EM - I get a gain of about 10m for your circuit and about 21m for the original EM..

Reduce your C2 to 10n and it will stand a much better chance of working I think.

(or perhaps even better - increase C1 to 470pF.. C1@1n with C2@47n gives exactly the same frequency response as the original EM.. But dont forget that +/- 10% is likely for capacitor values - and this is where the original EM design scores - because the attenuation is determined by the resistors which have much higher tolerance, and variations of the coupling capacitor (C3 on the VFO) make little difference - this capacitor can be any value 5n to 20n, so 10n +/- 20% is no problem)   

Fred.

" I have read somewhere that the antenna has a difference in capacitance of about 40pF depending on wether the hand is close or not." - Daniel

Oh, wouldnt it be easy if the above was true! ;-) .. Alas, its NOT!

You are looking at a change of no more than about 1pF over the sensible playing range - you get a massive increase in capacitance as you get really close to the antenna (a few cm) but a 40pF change is never seen.. most of the playing area one is looking for changes of a few tens of femto farads!

Fred.