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Theremax Schematic

The Theremax manual goes into much greater detail than the following brief design analysis. Hand and body motions in proximity to the sensing antennas produce frequency changes in a Hartley oscillator operating at approximately 750kHz.  The signal from this variable oscillator is mixed with a constant reference frequency in a ring modulator and the result…

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Theremax Tuning Revised

A quick tuning method (no test lead jump used): Back all four tuning slugs fully out (ccw).  Turn L1 and L4 one turn in.  Connect the audio output to an amp/speaker and set the Volume control R83 to about 3:00.  Set the Velocity to max.  Slowly adjust L3 inwards through it’s range listening for a…

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Theremax Controls

Controls Pitch & Volume Trim – these control provide a vernier null of the reference and variable heterodyneing oscillators in the Pitch and Volume control circuitry. Pitch CV – controls the range of control voltage produced in response to hand proximity to the vertical pitch antenna on the right side of the instrument.  Clockwise rotation increases range…

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On Theremin Tone

by John Simonton The 1929 RCA theremin is often used as a touchstone to assay the timbre of presently manufactured instruments. Nearly everyone notices that classic theremins have a very “string-like” voice. Also, like natural instruments, different pitches have subtly different timbres; the lowest registers can speak in nearly a vox humana. Some listeners find the…

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Theremin FAQ

MODS and More What is the range of the theremax. One octave? Two octaves? How hard is it to build my own case? Does the bottom have to be metal? Can I use the PAiA MIDIBrain with my Theremax? My oscillators drift and I have to keep tweaking the tuning … Can I get a…

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