I received a bare board and some of the SMD components for a OpenThereminV3, it is a semi-assembled kit that can be bought from Gaudi ( http://www.gaudi.ch/OpenTheremin/index.php?option=com_content&view=article&id=180&Itemid=115 ). The board I got was from a previous unsoldered kit where you have to buy all the components yourself. This totalled to another 35€ in parts as I do not have much SMD components in stock.
It is made as a shield that mounts directly on a Arduino Uno, which also makes the programmering very easy. Plug in USB, download source code from github, download the source to the controller and start playing on your new theremin!
The whole building process is very easy from just looking at the parts list and the schematic when you are in doubt, the silk screen layout is almost good enough to just use that along with parts list to solder it up correctly.
November 26, 2017
I made a video of the soldering and building process with a bit of testing it at the end 🙂
Here is some more detailed photos of the enclosure, antennas and boards inside. Starting with the Open Theremin V3 board where it is all soldered up and I am fairly satisfied with the result as I just used my regular soldering iron used for DIP components and a very thin solder.
The Arduino Uno board mounts directly on top of it and fits nicely inside of the enclosure.
I used 4 different colour knobs for the potentiometers so it was easier to remember which is volume, pitch, register and timbre, as I did not have anything in mind to use as a front with texts on.
The antennas is all done by hand and bend around a wine bottle, easily done and the result is absolutely perfect!
I did a quick test setup where it was just connected to a tube amplifier I have in my lab, in the future I will try to modify it for MIDI output which there is a separate guide on ( http://www.gaudi.ch/OpenTheremin/index.php?option=com_content&view=article&id=200&Itemid=121 )