The ‘Hugoniot Organ’. Charles-Emile Hugoniot . France, 1921.

Hugoniot's patent for a tone-wheel sound generator December 1919
A diagram from Hugoniot’s patent for a tone-wheel sound generator December 1919

CharlesEmile Hugoniot ( died; France, 1927 ) was a French mechanic, researcher and inventor of early electronic musical instruments. Hugoniot was awarded seven patents in France from 1919-1923 for various methods of sound generation including tone-wheels and photo-electrical tone generators.

Starting in 1919, Hugoniot began a process of improving existing sound generation devices of the period, first; Thaddeus Cahill’s electro-magnetic tone-wheels (from Cahill’s patent’s that would have been known to him in France) and continuing to electromagnetic steel discs and photo-electrical methods possibly influenced by the South African physicist, Hendrik van der Bijl’s patents from 1916. By doing so, Hugoniot introduced these new methods to a French group of electronic engineers.

Hugoniot Appears to have constructed only one instrument–  a photo-electric organ described in his patent (FR550.370) In 1921. The instrument was one of the first to use a photoelectric technique to generate sound: Hugoniot projected a light beam onto a selenium photo-voltaic cell through an array of 12 rotating discs cut with with concentric rings of radial slits. The frequency (and speed of rotation) generated an electrical pulse from the photo-voltaic cell that equated to an octave pitch.

Hugoniot’s died in 1927 before he could develop his ideas any further than prototypes yet he left behind a legacy of innovation that influenced a new generation of French pioneering instrument designers including Pierre Toulon and Givelet & Coupleaux.

Hugoniot's patent for a photo-electrical sound generator August 1921
Hugoniot’s patent for a photo-electrical sound generator August 1921

With this scheme the various types of wave forms for different timbres may be placed in radial sectors on a disk; another disk carrying the scanning slits in circular tracks rotates before this wave-form disk. A source of light and photocell complete the translating arrangements. Each slit track scans its corresponding wave cycle at a speed corresponding to one pitch of an approximate tempered scale. Thus, one wave and one slit track serve for each tone frequency of the tempered scale. Naturally the lowest pitch tracks are nearest the center and the highest are nearest the circumference of the scanning disk.

Another interesting arrangement is that used by Lesti and Sammis in the Polytone. Here, instead of using a series of similar wave-form cycles on a continuous track, with a single scanning device, only one complete such cycle is used with periodic scanning by a series of similar scanning slits, equispaced on a continuous track. The slit spacing is precisely equal to the wave-form lengths, so that this wave form is repeated at the scanning frequency; i.e., the number of slits passing it per second. The same method was disclosed as early as 1921 by the French inventor Hugoniot, who described an electrical musical instrument of this type in his patent’

A description of Hugoniot’s photo-electrical sound generation method from ‘Electronic Music and Instruments’ Institute of Radio Engineers, 1936


Bush, D., & Kassel, R. (2004;2006;). The organ: An encyclopedia. London: Taylor and Francis. doi:10.4324/9780203643914 P.167

‘Electronic Music and Instruments’ By Benjamin F. Miessner (Miessner Inventions, Inc., Millburn, New Jersey) . Institute of Radio Engineers. 1936. (

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