This French Army Fullerphone known as ‘Appareil de télégraphie secrète’ was developed
in World War 1 after one the British Fullerphone designs. It had a telephone embodied.
When preparing this page no other information was found as in a German World War
2 datasheet ‘Kennblätter fremden Geräts, Heft 13, Nachrichtengerät’. (Foreign Equipment
Data Sheets, Volume 13, Signal Equipment. See also WftW Compendium 3).
I am still looking for a larger original photo, including further information.
Circuit diagram of a French variation of the Fullerphone. This model had a built-in
telephone with an inductor calling device M. The buzzer/chopper was L with coil I;
contact 2 was connected to single headphone E1. Two batteries P1 and P2 were required.
A potentiometer P was provided for balancing out certain forms of DC earth potentials.