The Termen Effect
There are so many fascinating
fundamentals of nature that come together in the simplicity of
heterodyne theremin design, Lev Sergeyevich Termen was chosen to make these discoveries!
"Beyond 4 inches (10cm)
the belief hand
capacitance alone controls
the RF heterodyne theremin pitch is a factoid."
The hand-capacitance notion "has been" used as a simple
way to explain things!
are true hand
capacitance controlled theremins in the digital realm, but they lack sensitivity to aerial
fingering and will require you to use your entire palm for
Beyond 4 inches (10cm)
RF heterodyne theremin pitch variations are caused from
hand capacitance influences and changes in the
. This resistance is the total RF electro-magnetic power
transfered from the pitch antenna divided by the square of the net current flowing into the
pitch antenna. The pitch field is a dual
electrical/magnetic equilibrium, not just a capacitive field
as so commonly stated.
Here are a couple of different
Can pure hand-capacitance be
demonstrated as not completely logical?
Make a $10 "Lev" LC tuned antenna and it will reveal that the note intervals of the higher octaves next to the antenna
can be made wider than
the lower notes near the outside 18". This is in reverse of what
the pure hand-capacitance
logic would demonstrate.
"LC" of the tightly "coiled" tunable Lev
Antenna is the main feature that
gives you a
perfectly linear pitch field tuned to just below the
pitch oscillator frequency.
linear octaves can be available for play?
This is determined by the amount of energy from the pitch oscillator
which is "Driving the Antenna".
Three perfectly linear octaves are common but with good
oscillator design over
Three components influence what is occurring at the pitch
antenna. These are inductance, capacitance and
resistance. In the "RF heterodyne theremin",
pitch change occurs by variations in pitch oscillator
capacitance but not purely from your hand acting like a capacitor
plate. It is the loading effect of your hand near the pitch
antenna which changes the capacitance reactance
Xc of the pitch
capacitance is involved in the RF heterodyne theremin
model but it does not work alone!"
Below talks about
your standard un-tuned theremin and then a uniquely tuned one.
The closer your hand is to
an un-tuned pitch antenna
of a heterodyne theremin the denser the energy field. The energy in the heterodyne theremin pitch field is
"extremely" low. The Thereminist neutral body
mass is a good "neutral reservoir" to absorb this energy
from the emanating RF energy and capacitive interaction. The theremin players hand/arm has less resistance
than the air space so
your forward playing pitch fingers transfer energy into your body
Your body's ability to
absorb a charge is demonstrated when you scuff your feet on the
carpet then get an electric shock when you touch the
The heterodyne theremin must have a good earth ground, not
theremin earth ground is poor you will hear distortion in the wave shape of
the RF heterodyne generated theremin tones. The theremin RF
energy relies on
weak ground currents and uses the
earth ground as part of the antenna system.
As the Thereminist hand approaches an un-tuned
pitch antenna, an
increase in the energy transfer
occurs in the antenna. This decreases the "capacitance-reactance Xc" of the
L1 antenna side pitch oscillator.
This loading capacitance-reactance has the same effect as
slightly increasing the capacitor value in the LC circuit of the pitch oscillator.
The frequency now goes lower as it feeds more current into the
pitch antenna. As
the antenna side oscillator goes lower the
theremin tone goes higher
as the pitch oscillator frequency
moves lower, away from the reference oscillator
frequency. The theremin tone is the difference of the two RF
oscillators, simple so far, eh?
In a Tuned theremin Lev Antenna the overall LC
of the coiled design "regulates" with perfect linearity, relative to a
musical scale, the amount of energy capacitively transferred
between the player and the pitch
antenna. The Lev Antenna energy level determines the number of
playable octaves in the theremin pitch field.
energy transfers near the Speed of Light.
is an instantaneous change"
so not an actual energy flow or
LC oscillators that
are typically used in a RF heterodyne theremin, tuned to the same RF frequency
with their two coils in proximity will influence one another's wave
Very loosely coupled, the oscillators will lock into
synchronization. This creates the "Null Point" where no theremin sound is heard.
The Null Point is also the "zero point"
where the reactance Xc &
XL of both oscillators equal
zero when both their frequencies match. The
moment before the theremin locks onto the null point is where the theremin demonstrates its
maximum sensitivity. A well tuned RF heterodyne theremin
antenna can give a
response to your neutral body mass over two meters away or
lets say 6' to 8'. (This response distance is quite remarkable for such
a low capacitance and energy field, but not very useful for music.)
The RF heterodyne theremin's audio frequency (sound) is the diode detected
or mixed AM
frequency difference of the two
RF oscillators after breaking out of the Null Point.
This process of heterodyning or beating the oscillators frequency with your interaction in
the theremin RF electro-magnetic pitch field creates:
audible musical tones known as the "Termen Effect".
When perfect pitch linearity occurs
it's Lev Sergeyevich's gift for you. .