When I first got into making Theremins I ordered the Theremin Vision kit. I had a hard time getting it to work at first, but finally got it running OK.

At the moment I only seem to get about 12″ of usuable range.

My reference oscillator runs at about 1.67MHz and the sensor oscillator is running at 1,54MHz.

A 4013 flip-flop does the necessary combining and filtering. A 14 bit ripple counter then gives a range of frequency responses.

Hooking up a piezo buzzer to any one of the “bit” output lines creates an audio tone – just like the original Theremin.

Did the Sam Ash MIDI clinic last night, and learned one valuable lesson about the Theremin. If you leave it in your car, in the sun, it don’t work no more…

Had to take off the lid and leave it for about an hour to cool down so that the coils dropped back into tune.

I recently got off my butt and finished the case and MIDI interface for the Theremax.

This video shows how bad I am at playing the Theremin. The first clip shows the continuous mode where the pitch antenna is controlling the pitch bend wheel. The second shows a more discrete approach, with a blues like scale mapped to the pitch antenna.

Still really hard to play though…

Still a long way to go with this, it really needs a “Theremin VST” with special control mappings to become as expressive as the real thing.

The next thing I need to examine is scaling the pitch response to give a more linear feel to the instrument. Along with some kind of calibration mode.

I am seriously hooked on building my own synths and effects now. The modular approach to sound design is really engaging, and the fact that I have to build the modules myself means that I’m willing to invest much more time in using them than some of the modern digital gear.

I found a great site – Music From Outer Space – full of module plans and designs for effects units.

I’m going to be following some of the designs and slowly putting together a modular synthesizer in an old piano cabinet I have at home.

Another great site is this one Tonepad – guitar FX schematics and designs.

I just completed testing on my build of the PAiA Vocoder kit. This was a tough one, and officially I’m not done yet, as I have to get the noise reduction mod fitted and working.

Here’s a video that explains a good testing strategy once completed…

…and here’s a video that demonstrates what the Vocoder effect is…

The Vocoder kit can be obtained from here.

Thanks to Scott at PAiA for his help in getting this up and running.

I finally found a place just south of Indianapolis near Edinburgh where the light pollution was low enough to get this shot of the Milky Way – I’m assuming it’s the Milky Way and not just some really high clouds.

It was a 30 second exposure at F2.8 with a fish-eye lens. I used the Nikon D300 camera.

Milky Way

30 seconds is about the limit for fixed exposures. The next step is to get my telescope mount calibrated so that I can use it to track the rotation of the earth and make longer exposures.

Hmmmm, so after a long period of flawless service, my copy of Wordpress has started to run out of memory.

When I try to upload images I get “Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 2144 bytes) in /blog/wp-admin/includes/image.php on line 147″

It looks like the amount of memory allocated to PHP has been overrun, I’m still looking into how to either fix it, or allocate some more memory.

Which is a shame, as I’ve got a bunch of new stuff to post about…

Like my new Vocoder build.

UPDATE: I added a line to the .htaccess in the root of the website to increase the memory allocated to PHP to 64Mb – this seems to have fixed the problem (for now).

After I finished the 9700 I was looking for a way to test it as a whole. The one thing missing from the PAiA website was a test patch with a sound file, so that you can check to see if all the bits are doing what they should.

I think that my synth is actually working OK, and all the problems I had were just down to bad patch cables.

Here’s an image of my latest test patch, that tests the MIDI, OSC, modulators, filter, trigger, gate, and ADSR.

Click here for the patch image.

This patch uses the VCO modulator to create the rhythmic PW pulsing effect, then the VCF modulator in cycle mode to create a simultaneous slow rising and falling sweep. The MIDI Trigger and Gate outputs are patched through to the ADSR in the VCA.

Note: I accidentally wired the switch backwards on the VCA, so even though it is set to ‘Cycle’ it’s really in ADSR mode.

And here’s the patch in action…

I’m really impressed, this is with no effects or anything, just the synth. Even the Juno’s needed a bit of chorus to liven up the sound.

I bough 15 dollars worth of stuff from Walmart the other day, just so I could make one of these:

I got the idea from the excellent http://www.cibomahto.com/ website.

Keeps me entertained for hours, but then I’m that kind of person…

I just spent about a week building the 9700s modular synth. It took a bit longer than anticipated – but these things really can’t be rushed.

I now know why analog synth gear costs so much – it takes forever to assemble!

I hooked up the Theremax theremin to the CV of the VCO just to see what would happen.
(The oscilloscope is a general USB module from Measurement Computing.)

The range is a bit shallow – maybe there’s something I can do about that with an op-amp or two…

That’s got the 9700 completed, next on the list is the vocoder…