Let's Design and Build a (mostly) Digital Theremin!

It's All A Trick!

My playing technique consists of a series of what most Thereminists would consider to be tricks, cheats, or crutches.  And you know what?  I don't care!  I'm having fun and almost feel like I'm singing sometimes, and that's plenty for me.  All I ask is that a musical instrument pull me in and make me want to play it, and so few do (but I'm a dabbler, in constant need of a quick and easy fix).  The tricks:

1. The near pitch field is linearized and
2. the antenna is a plate, so I don't have to change my fingering when playing over the entire field. 
3. Indeed, I play with an extremely relaxed note spacing of 4 half notes per open/closed hand so I don't even have a fingering technique to speak of, and my vibrato is just waving my hand like a dead mackerel (Peter Pringle says this is bad technique, and it likely is on a typically tight analog Theremin, where fingering tends to be essential). 
4. I use highly aggressive though subtle sounding pitch correction, and
5. I watch the LED tuner like a hawk. 

With all of these things together, honestly just about anyone could be playing simple tunes pretty passably in a couple of months without everyone cringing.  And with the relaxed pitch field I don't have to use a special sit/standing chair to casually stand normally at the thing and stay in tune without a frozen statuesque pose. 

Will all these tricks keep me from being the next Katica or Grégoire?  I mean, what were the chances in the first place? ;-)  And I have no desire to perform publicly anyway.

I had high hopes for the "RESPONSE" knob on the Claravox to yield significantly wider note spacing like I use, which could be fundamentally transformative to the various approaches to Theremin playing, but unfortunately it doesn't seem to have the range necessary to do this.  And I now understand why the Claravox only has pitch quantization, and not true pitch correction, as it lacks any form of responsive absolute pitch feedback mechanism.  I can play a cappella all day long with zero drift from where I started.

Kit Progress

Today I made a jig to quickly and easily test all the I/O at the expansion connector.  Also finally spent a lot of time analyzing the new AFE PWB and coil box arrangement:

Initially saw gobs of scary noise and interference, which traced back to the same old low 5V cause, and powering the USB via my tablet charger rather than the Amazon basics crappy USB extension cable off my PC fixed that.  The capacitors I printed on the PWB seem to be working as well as the plug-in NP0 caps, so I think I'll go with those as they are basically free, variable in 0.5pF steps, and should be able to withstand much higher voltage.  Will need to print for at least a week straight to finish things out, hope my Ender 3 hangs in there.

Tried swapping the pitch and volume boxes, but after seeing yet again the interference that higher frequencies cause lower frequencies, I'll stick with keeping the pitch above the volume, as the pitch is much more critical, and I've never really noticed any interference on the volume side.  This is "non-traditional" in a standard practices Theremin design sense, but I've never seen any interaction between the D-Lev fields (unless it was operating ungrounded), and I think analog Theremins maybe cut corners here to minimize the size and cost of the volume side inductors.

Another experiment I tried today was to leave the volume side AFE disconnected, which causes the LC DPLL to constantly "hunt" for lock.  It didn't seem to affect the pitch side, so pitch only sculpture mode should be a pretty simple hardware subset of the full Theremin mode kit.

Dewster < “My playing technique consists of a series of what most Thereminists would consider to be tricks, cheats, or crutches.  And you know what?  I don't care!  I'm having fun and almost feel like I'm singing sometimes, and that's plenty for me.  All I ask is that a musical instrument pull me in and make me want to play it, and so few do (but I'm a dabbler, in constant need of a quick and easy fix).”

For the vast majority of people who just want to make music - without worrying about public performances, the only thing that is truly important is to have FUN! No need to apologize for that! While the ultimate goal of most instrumentalists is to “sing” with their instrument, playing the theremin seems to require skills that more closely resembles singing than playing an instrument (and then trying to get that instrument to sing). So, don’t apologize for “cheating.” After all, the RCA instruments were originally promoted as something “everyone can play.” I think that what you done with the D-Lev will appeal to a broad range of musicians - rank amateurs and those with considerable expertise. I’m eager to hear how it will be received by others.

I know that I’m finding the D-Lev to be very useful for me, although I use some of the tools you’ve provided, like the tuner differently. I have found that I really like the tuner when I’m practicing scales and intervals. I like it a lot! However, other than to find my starting pitch, I don’t watch it at all. Regardless, it’s fun to play!

After all, the RCA instruments were originally promoted as something “everyone can play.”  - ContraDude

I think about that a lot.  I guess it's standard marketing, but it was also a time before prepackaged entertainment and social media took over everyone's lives, and people had to actively entertain themselves in order to fill their lives with music.

Duke, Duke, Duke, Duke of Coils, Coils, Coils*

Today I wound seven 1mH (pitch) and eight 2mH (volume) coils for the D-Lev kits.  They still need leads and clear heat shrink, but most of the tedious work is done.  There's a huge difference between winding 30AWG and 32AWG (not to mention fewer turns)!

*To be sung like the hooker in "The Man With Two Brains".

Oh (milli-) Henry!

Coils with wire leads & clear heatshrink tubing on the outside.  All measured and ready to go.  On to building 16 AFE PWBs.  Still 3D printing coil & AFE boxes, should be done with those in a day or so.  Running low on Army green PETG, and Amazon seems to be out of stock too, may have to switch to white for the last couple.  I probably should have used clear so people could see inside them.

Found 3 bad encoders!  Name brand (Bourns) from a reputable vendor (Mouser)!  I tested the all the switch contacts for continuity before mounting them and found nothing wrong. But on the D-Lev they worked fine in one direction but were intermittent in the other direction (some detents produced no change, and fast spins produced very little change).  3/80 is almost 4% bad, which is insane.  Never saw this level of failure from the cheap Chinese encoders off eBay.  Sure, they can wear out after a lot of use, but they always work fine when new.  I'm testing everything I can before soldering, but this caught me by surprise, really awful.  The Bourns are supposedly rated for a healthy 100k spins, but this doesn't bode well.

AFE build

Soldered up 16 AFE's today:

Ran out of strip socket so made yet another Amazon order (I'm super quick on the "checkout" trigger finger these days).  They had the Army green PETG in stock so I ordered a reel of that too.

I've never soldered so much in my life!

And at night, do you dream that you are still assembling D-Lev theremins ? 

Logo Plates

Playing around with the logo plate artwork:

Tried moving the radiating circles inside the 'D' but it ended up looking like a Target ad.  I'm partial to the simpler one at the top and the one at the bottom (both sans circles) and so am planning on shipping one of each with the kits.

"And at night, do you dream that you are still assembling D-Lev theremins ?"  - Mr_Dham

I dream of electric sheep!

Playing around with the logo plate artwork:Tried moving the radiating circles inside the 'D' but it ended up looking like a Target ad.  I'm partial to the simpler one at the top and the one at the bottom (both sans circles) and so am planning on shipping one of each with the kits." < Dewster

I agree, the “Target” version simply doesn’t cut it! Personally, my favorite remains the “Quasquicentennial” version (similar to number 2 above) that you posted earlier! LOL!