Home-brewed Theremins ... and other strange devices


Theremin Construction / Test Videos

The "musical performances" are intended to present the "voice" which can be achieved with simple circuit arrangements, based on the original work of Leon Theremin. They claim no musical beauty or properness.

Rockmorizer Kosmos-XN Theremin Test (2016)

Rockmorizer Kosmos-XN Theremin Test (2016)

To test the general circuits of a Rockmorizer Silicon Theremin instrument, a modified Kosmos experimentation board was used. The circuit is close to the techniques later applied in the Rockmorizer Silicon 2017 Theremin instrument which is based on the original design of Leon Theremin, producing the sound spectrum which is assumed to be close to the instrument of Clara Rockmore. The circuit generates a single-sine audio signal which is formed to rectangular like pulses with appropriate pulse-width to match the desired sound spectrum.

US-Tube 'UST' Kosmos Theremin Test (2015)

US-Tube 'UST' Kosmos Theremin Test (2015)

To test the general circuits of the C. Rockmore-  and L. Rosen tube Theremins, a modified Kosmos experimentation board was used which holds vintage 1920s tubes (3x #27 tube, 1x #24 tube). Due to limited board space, the volume control was realized applying ‘modern’ Noval tubes.

Russian Miniature-Tube Theremin Test (2015) Part 1.

Russian Miniature-Tube Theremin Test (2015) Part 1

To test the general circuits of a low voltage miniature tube Theremin instrument, applying Russian miniature-tubes, the ‘Russian Miniature-Tube Theremin’ was realized using a modified Kosmos experimentation board. Surprisingly, this experimental Theremin prototype showed awesome formant effects when the setting of the proper pulse-pause ratio was met according to the original designs of Leon Theremin.

Russian Miniature-Tube Theremin Test (2015) Part 2.

Russian Miniature-Tube Theremin Test (2015) Part 2

The ‘Russian Miniature-Tube Theremin’ may serve as a basis for the development of a beautiful sounding low voltage tube Theremin instrument. It must be noted, that the formant effects are caused mainly by using vintage 1920s interstage transformers. Those have to be replaced in the final ‘modern’ circuit, preserving the formant filtering.

Etherwave Standard Theremin simplest ever ‘Lower-Register’ (bass range extension) modification (01-2018)

EW simplest lower-register modification

For those who only like to expand the lower register, preserving the EWS Theremin sound and circuit, a very simple solution has been found. The EW Standard Theremin bass modification only applies a trimmer capacitor of 1pF to 4pF and a 150kOhm standard resistor as described in the ‘Etherwave Standard Theremin simplest ever lower-register modification’.

Etherwave Standard Theremin 'Rockmore-Sound' Modification Test (05-2020)

EW Theremin 'Rockmore-Sound' Modification

It is possible to implement a simplified (rectangular) audio-shape, which is quite close to the Rockmore instrument sound, using the already existing components of the EW Standard Theremin and adding a few additional parts, as described at EWS Theremin Rockmore-Sound Modification’.

Rockmorizer RT-6SH2P Tube Theremin Test (03-2020)

Rockmorizer RT-6SH2P Tube Theremin Test

The RT-6SH2P Tube Theremin applies Russian 6SH2P (6ж2п / 6AS6) dual-control tubes. It is realized for circuit testing at a modified Kosmos experimentation board which can hold up to five 7-pin miniature tubes; only four are used in the RT-6SH2P circuit. This theremin was designed to test the application of 6SH2P (6ж2п / 6AS6) tubes for generating the Rockmore sound (limited single-sine pulse sound spectrum).

Rockmorizer RT-6SH2P-X Tube Theremin Test (10-2020)

RT-6SH2P-X Theremin sound & pictures demonstration video

The RT-6SH2P-X Theremin represents the extended version of the RT-6SH2P tube Theremin. In contrast to the simplified RT-6SH2P tube Theremin, where the volume is controlled by a bowden thread, the RT-6SH2P-X enables the player to fully control volume and pitch by the wave of the hands without touching the instrument.  

FRANZIS Theremin Kit Modification Test (09-2020)

FRANZIS Theremin Kit Modification Test Video

To save the FRANZIS Theremin kit from being thrown into the trash can, attempts have been made to convert the unit to a playable nicely sounding Theremin instrument with (simplified) volume control, usable pitch response and grounding facility.  

 Vintage Devices Collection Videos

Radiostat-Heilgeraet (Violet Wand)

Radiostat-Heilgeraet (Violet Wand)

This vintage 1920s Radiostat-Heilgeraet generates high voltage RF, enlightening neon lamp tubes of various shapes which have to be positioned to locations of the human body which have to be ‘healed’. In general, this vintage quack devices apply chopper/vibrator units to drive a parallel L/C resonator, consisting of a coil with high lumped capacity. Due to the high L/C ratio, the generated RF voltage as well as the provided currents are quite high – just as well as the radio interference.