Of the Theremin Making

Giorgio Necordi’s short report about the making of his transistor theremin.

After a long wait it’s time to come out and unveil the instrument based on my long time experiments with theremins. This is the theremin you can hear in the “theremin samples” section of the thereminvox.com library The entire instrument was completed during 2003 and revised many times during 2004 and 2005. What follows is a collection of specifications, images and mechanical details of the instruments.

Instrument specifications
Musical range:5 1/2 octaves – 3 octaves above middle C
Controls:Pitch tuning, volume tuning,waveform, high tones cutoff, mute switch, power switch, power on led
OutputsAudio, tuner/pitch preview
Power supply:External – 11.50 Volt
Volume antenna:standard loop antenna
Pitch antenna:telescope rod antenna partially opened
Playing arc linearity enhancer:Big air coil
Pitch oscillators frequency work:210 KHz
Volume oscillator frequency work:440 KHz
Necotron transistor theremin. Frontal view.
Frontal view.
Necotron transistor theremin. Orthogonal view.
Orthogonal view. The instrument controls stick out from the window on the main chassis.
Necotron transistor theremin. Back view.
Back view. The back panel flap down to access the innner area.
Necotron transistor theremin. Back view with back panel removed.
The back panel was removed to show the inner area as well.
Necotron transistor theremin. Electronics and air antenna coils.
Electronics and air antenna coils are mounted on a single panel. The panel can be suitably extracted from the main chassis.

Necotron transistor theremin. Electronics.
The electronics are held inside a internal metal enclosure. Antenna coils are hand wound with #32 AVG enameled copper wire.
Necotron transistor theremin. Instrument controls.
The instruments controls are mounted on the frontal panel of the internal enclosure. Note the prototype circuit built on a perforated board.
Necotron transistor theremin. Back panel with trimming screws.
On the back panel of the internal enclosure are located the trimming screws of the oscillators frequency.
Necotron transistor theremin. External chassis.
External chassis physical dimensions. All measures are in millimeters.
Necotron transistor theremin. Internal enclosure mounting.
Internal enclosure mounting. All measures are in millimeters.
Necotron transistor theremin. Internal enclosure.
Internal enclosure physical dimensions. All measures are in millimeters.
Necotron transistor theremin. frontal panel layout.
Frontal panel layout.

8 thoughts on “Of the Theremin Making

      • iiro
        iiro says:

        > >
        > > Hi,
        > >
        > > I would be interested to have a copy of the circuit
        > diagram
        > > (and coil specs) that you used. Any chance you could
        > add
        > > them to the story?
        >

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