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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.

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)

 

 Updated 1.26.19

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