Open.Theremin V3 Build Instructions

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Published: Tuesday, 18 October 2016 07:56

The Open.Theremin is a DIY (do it your self) project to build your own real theremin. With the open source hardware and software description you can learn about it's functionality, build your own and adapt it to your needs. The electronic circuit is available as a assembled and tested board in a kit with easy to solder electronic and mechanical parts. The electronic circuit needs to be combined with an Arduino UNO, the popular open source electronic development platform and a pair of antennas to make it a playable instrument.

Contents of the kit:

Building step by step:

1. Complete the shield - solder the pins, the push button, LEDs and the knobs
2. Connect a pair of antennas
3. Connect an audio system such as an active speaker or audio system
4. Set up and Grounding
5. Programming the arduino
6. Starting the auto-calibration

And you theremin is ready to play.

Here is the detailed in instruction manual:

Antennas

You can basically use any electrically conductive material as antennas. The picture shows how to connect two aluminium rods (can be found in most hardware stores) with an inner diameter of 4 mm using the supplied spring plugs (banana plugs). The total length per antenna should be around 40 to 50 cm. You can easily bend antennas form aluminium tubes of 6 mm diameter by hand to the desired shape. To build the theremin into a case you can also use stiff wire to connect the antennas.

The following drawing shows how typical theremin antennas would be bent:

Open.Theremin V3 - Next Generation Theremin

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Published: Tuesday, 18 October 2016 06:19

Open Theremin is an open source hardware and software project with a great community of musicians and people interested in the world of electronic music instruments . The aim is to build a next generation, digital version of the legendary music instrument. With more than 1000 Open.Theremins in the world the new version 3 was built based on many community ideas and inputs.

The Open.Theremin V3 was built on the experience with the previous versions of good quality and affordable digital theremins such as the Open.Theremin.UNO. The electronic shield was completely redesigned and integrates a lot of new and exciting features. The layout and graphics are designed by the Berlin based inventor and artist Niklas Roy. Four good quality ALPS knobs, a big button and two 5mm square LEDs make a simple and intuitive interface. The black circuit board with golden letters fits well on an Arduino.UNO and makes a most compact theremin instrument (100 mm x 60 mm).

Open.Theremin V3 with with Antennas.

Features

Full auto-calibration was since the beginning of the project the most requested feature and is now fully implemented. Uwe Kutschki, development engineer from Germany, Thüringen made important contributions in implementing it and now it is here. The valuable feedback from Swiss Theremin player Coralie Ehinger helped to make the new Open.Theremin a playable and real theremin. Here the full list of features:

• Pitch and volume antenna with excellent linearity
• Full digital auto-tuning (one button press)
• Pitch and volume can be manually fine tuned during play
• Sensitivity of the pitch antenna can be changed in 4 registers
• 8 preprogrammed audio wave forms can be selected
• Mute function
• Waveform can be reprogrammed freely (stored in a look-up table)
• Arduino compatible shield for easy re-programming and mollifications for own uses.
• Completely open source hardware and software
• USB powered, no extra power supply required, battery supply possible
• 12bit digital audio converter
• Control Voltage (CV) option

Open Theremin V3 - Schematics

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Published: Tuesday, 18 October 2016 07:21

The Open.Theremin V3 is designed on KiCad, the open source PCB design software. The schematics includes different clearly separated functional blocks.

Open.Theremin V3 Schematic - click on the schematics to get a PDF version.

Functional blocks:

PITCH: Variable and fixed frequency pitch oscillators. LC and quartz resonators operating at 500kHz output frequency.

VOLUME: Identical variable and fixed frequency oscillators for volume. Different centre frequency of 460kHz to avoid interference.

AUTOTUNING: Auto-tuning circuit based on a BB914 variable capacitance diode. Software controlled through voltage generated by 2x 12bit DAC (MCP4922).
Frequencies of the two variable oscillators as well as the Arduino quartz frequencies are measured to characterize the antennas and tune the oscillators automatically.

MIXER: Digital mixer based on a D-Flip-Flop 74HC74

AUDIO DAC: 12bit audio converter  (MCP4921) with rail-to-rail operational amplifier

ARDUINO AND INTERFACE: Arduino UNO, distance of hand to antenna is converted to a digital value and audio signal generated through a look up table

Open Source Hardware

The source code on GitHub can be found here.

The Community Theremin

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Published: Monday, 19 July 2010 20:28

Welcome to the Open.Theremin Website.
Open.Theremin is a open hardware and open software project.


Coralie Ehinger playing the Open.Theremin

Coralie Ehinger is a Swiss theremin player and organizer of the first Swiss theremin festival N / O / D / E. She runs etheremin, a French theremin platform and gives lectures on the history and the art of playing the theremin at schools.

For more information on the newest arduino theremin shield see Open.Theremin V4 and check out the News.

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