When
I decided to explore what the theremin was all about I had not heard of
Lev Sergeyevich Termen or Robert Moog. It was Brian Wilson who brought
it to my attention in 1966. As fate would have it I later became friends
with Paul Tanner and his lovely wife Jan who lived not far from me.
My
friend had a nice whistle with his electro-theremin or
what he just called The Box.
Paul
Tanner
The
Tannerin
of Master Builder Tom Polk is of excellent design, construction and
sound.
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I had no approach
or knowledge when I started other than my Amateur Radio background to
lean on. To keep it simple I would
only used parts I could purchase from my local Radio Shack, a local chain
electronic store that was big here in the States. Some viewed this as limiting
myself, I viewed it as developing the discipline necessary in my
learning phase which still continues today.
The results
of my first theremin like build was pitch only that sounded like a mouse
getting its nuts squeezed. LOL
From the
first build I became obsessed with what in the process creates the big
natural sound and
not a cheap whistle or worse a distorted kazoo sound. I would eventually
figure out the answer rests in unique knowledge and
approach... rather than computer modeling and precision calculations.
- Below
are original Phoenix 2020 circuits that evolved over time -

The Electrodeum
Pitch Antenna approach came to me first, it created perfect pitch field
linearity. I did not know what I had until years later when I purchased
my first EtherWave Standard, to know what non-linear is. This was around
2003, because electronic engineers did not know how to computer model
it, most rejected trying it. Are the results better than series tuning,
I will let others verify that.

I think the
most difficult thing about theremin design to learn is how to keep the
two oscillators from interfering with one another which then causes
unwanted distortion in the audio signal.
The above is the last piece of
my theremin design that came during the making of this Phoenix 2020
webpage in 2018. L3 picks up the magnetic field from L1, L2 and L4 at
the base of the Electrodeum. (The Becker Electrode) The signals
heterodyne (mix) in the D1 diode, which is a beautiful phenomenon of
nature, while the rest of the time they just bounce around in space
ignoring one another.
Remember I mentioned
what develops the Big
Natural Sound? There
are seven aspects!
The
first step is through the Electrodeum,
the second step is using the MPSA42
transistors to excite
the Electrodeum, the next step is the inductive diode
detection. In the
audio section it using an audio
transformer and a
special little trick I figured out using the VO618A optocoupler
and last but not least it is the influence of the 555
on the sound. Out of all of this the combination has a Perfectly
Linear Pitch Field
making it a very playable musical instrument. Finding one of these ideas
might be 10,000 to 1 but all of them combined leads me to believe there
was some sort of spiritual guidance shining on my journey.
- I can
not emphasize enough the importance of a direct earth ground in all of
this -
The theremin if
understood gives you a mystical connection with mother earth.
The piano keyboard layout is man made, the theremin will match it
perfectly!
This all
could have been done with parts carried by Radio Shack at the beginning
of my journey. The thing that limited most was imagination and
inspiration. This approach could never have been found just using
Computer Modeling which I think stymies creative growth.
If an
engineer is throwing a lot of math around instead of results, he
probably does not have a clue!
PWM
volume control, more responsive (explained
soon)
PWM
Pitch Preview Volume in Reverse (explained
soon)
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