The RS Theremin Ultimate 2c Dual Voice

The Ultimate 2c - Bookmark this private development web address!

RS Theremin - Ultimate 2c
100% Radio Shack

Build this Ultimate 2c - a "true heterodyne theremin voice"
as Lev Sergeyevich Termen discovered in his laboratory.

All of my theremin boards are "Pitch Only", I use an external
Cds photo resistor technique to control the volume.

New RS Illusion PDF theremin board as of 06.22.08

Important: Improvements for the Ultimate 2c

Analog Ultimate 2c Sound Bytes

Excuse my flat notes, I am not a musician. LOL

upper_reg_r.mp3 (270kb) 07.19.07 A4 466 hz tune, then a three octave jump with easy playing at A7 3600 hz.

Above is an upward pitch sweep to show how perfect pitch linearity allows the extremely high notes
to play with precision next to the Lev Antenna. "You could have my control in a week if you can whistle."

levbrato1.mp3 (185 kb) 08.04.07 Analog sound with Levbrato, a method of real time auto-vibrato control.

Listen to how noise free these samples are below, the gradual fade-in and the
non-distortion of the sound using the CdS photo resistor, not to mention perfect vibrato.

clara_test7.mp3 (225 kb) 04.03.07 The Clara sound comes from a yet to be revealed external technique.

clara_test8.mp3 (180 kb) 04.04.07

In Windows Internet Explorer press F11 to expand to a larger view.

Schematic from 07.18.07

New RS Illusion PDF theremin board as of 06.22.08

Original board date 7.18.07

Lev's Antenna for Total Theremin Note Control
C4 & L3 seen on the above photo are part of Lev's Antenna.

Improvements of the Ultimate 2c over the Ultimate 2b below:

The Lev Antenna must be used for the ideal response. This Ult-2c board L1 coil modification (two 100 uh chokes) creates a solid five or more linear octaves instead of the just over the three Ult-2b original. It is also a bit more sturdy in design.

Adding a tickle loop wire draped over the L2 coil can sometimes improve the audio wave shape .

I added voltage regulation to the new Ultimate 2c pc board (zener D3) . This minimizes retuning due to pitch drift caused from minimal battery decay over the playing session. It also separates the operating oscillator voltage of the transistors from the amplification chip TL082 voltage. The oscillators seem to sound better for pitch & wave shape around 5.2 volts. The IC chips work better powered from 6 to 9 volts.

Visit My Lab

The ideal layout for a theremin is in a vertical format. I have all the right components hanging off of cardboard on a wood stick. This gives me temporary freedom from any construction influences. The blue marble has a CdS photo resistor under it. I have no doubt that the crude structure you are looking at in the photo surpasses even the finest theremin out there, in response and natural voice.

This narrow design allows for a pillow case type sleeve to cover and protect it. The antenna spring can have a wooden dowel inside for rigid support and make it removable. You want a clean stand alone look.