Theremin construction.

[Martin Czech]

At 800kHz the field is allready electro-magnetic.  A closed thin alu
foil housing should therefore eliminate radiation, the problem is: you
(the player) do not want to be enclosed!  Since the Theremin is driven
by hand capacitance any antenna shielding would destroy the performance
due to shunting this capacitance via enclosure capacitance.

I.e. the field is there to interact with you, so you will always emit
a lot of (unallowed) radiation.

Perhaps you need to have a Theremin room, all walls plated with 1.0mm alu.
This will also eliminate EMI into your Theremin.

Watch out for the federal post agency! If they detect you it could be
an expensive experience!

m.c.


:::X-Sender: uzs159 at mailout.uni-bonn.de
:::Date: Tue, 08 Aug 2000 14:16:11 +0200
:::To: synth-diy at node12b53.a2000.nl
:::From: René Schmitz <uzs159 at uni-bonn.de>
:::Subject: Theremin construction.
:::Content-Transfer-Encoding: quoted-printable
:::
:::Hi all,
:::
:::I'm working on a tube theremin. I've started with the two pitch
:::oscillators, which work at arround 800kHz. I've hooked up a simple
:::germanium diode as "demodulator", and this thing already sounds quite nice.
:::(Although in the end, I'll use grid rectification.)
:::However what annoys me - and probably my neighbors too - is that it acts as
:::a little AM transmitter. I guess its the magnetic field, since ferrite
:::antennas 
:::don't pick up the electric field.
:::
:::How would I go about shielding it?
:::
:::Bye,
::: René
:::-- 
:::uzs159 at uni-bonn.de
:::http://www.uni-bonn.de/~uzs159
:::
:::