Model 1910 'Marty'

[FABphones]

Wiring schematics - Model 1910 'Marty'

[dsk]

Interesting solutions, if I understand this right it is possible to use on CB and LB power supply as this:
dsk

[countryman]

Correct, it could be wired for LB or manual CB use. Then a capacitor would go into the battery box.
The upper diagram in FABphones post is an earlier version of the Marty, the photographed sticker is a later model already providing an anti sidetone coil.

IIRC also early german manual phones could be wired for LB or CB operation. Check www.erel.de : http://www.erel.de/INH/10/1010050/1010050s.gif
The gothic print is hard to read.