Hello Hauke, Your discs are similar in hole type and spacing to a
small organ I have called a Diana. My organ has outside drive, and
the discs you have appear to be center drive. I suspect that your
discs were made for an organ of the same family though.
Schmidt & Co. of Leipzig, known as the Phoenix Musikwerke, made several
models. The Lucia was a 12-note scale and used a 12 cm. disc, according
to the Bowers "Encyclopedia." That sounds like the discs you have.
Although on page 751 the Encyclopedia says it plays cardboard discs, it
mentions metal discs elsewhere.
These tiny organettes have a sweet sound and the musical arrangements
are very good for the limited scale available. Hope someone has a
machine to play your discs.