Open.Theremin Tweaks

Yasushi Yoshida

Musician and audio equipement designer Yasushi Yoshida experimented a lot with the Open.Theremin and came up with many improvements, tweaks and fun stuff that you should not miss. He publishes all his findings on his independent blog AudioHologram . Most of it written in Japanese language I try to give you an overview of his great work here:


Open.Theremin on Arduino Mega 2560- link1, link2

Open.Theremin on Arduino Leonardo - link1

Open.Theremin with special core - link

Testing the VCO - link1, link2, link3, link4, link5

Special coils and capacitors for improved temperature stability - link1 - link2

High end shielded connectors - link

Open.Theremin with LED - link

Control Voltage - link

Pitch and Volume Knob and wave table switching - link1, link2 , link3

This feature has been integrated in the extended version of the Open.Theremin V2.0


Elmo' A MacDonald

The following code written by Elmo replaces the "Volume" function of the Open_Theremin_UNO_expanded with an LFO Rate knob.

This varies the Tremolo Rate from OFF to almost Ring Modulation. An existing wavetable is used as a LFO "signal" to amplitude-modulate the output.

A sample is taken at every iteration of mloop...

The lowest LFO rate advances through the wavetable one sample at a time.
Higher rates "skip" samples to advance through the wavetable faster.

The pot1 value determines how many samples are "skipped" each time mloop runs.
Slower LFO rates get a better-defined shape (exactly as required).

Download the code here:



Uwe Kutschki

Open.Theremin with VarioCaps for autotuning. The idea is around for a while and is definitely on the wish list of many of you. So here it is, Uwe designed a schematic and even sent me a first prototype - wow. The software also needs some extra code and I did not get to open his Target 3000 files yet. I will post more as available.

Schematic of Open.Theremin.UNO with VarioCaps for autotuning by Uwe Kutschki.

Uwe is development engineer and likes to work on music and electronics. He also has some more ideas for improvement and is even thinking of design a luxury version of the Open.Theremin some day.


Thank you all for your great work.