The Junghans J80 / 12 was the first German movement with power reserve indicator. During this time, some customers did not trust the automatic winding, therefore Junghans decided to solve this problem with a display of the power reserve. With this watch to Junghans ventured into the field of automatic watches.
Anders als bei den herkömmlichen Junghans J80 verwendete man eine autokompensierende Flachspirale und eine Spezial-Nickel-Unruh, deren Ausgleichsschrauben im Reif versenkt sind. Die Entwickler ließen sich das Differential-Getriebe zur Ermittlung der Gangreserve patentieren, der Rotor besitzt einen Schwermetallreif, der beidseitig über einen Wippen-Wechsler bis zu einer Gangreserve von 40 h aufzieht.
Here is an example for the version with a black dial.
In the archiv of the Workshop you can find the revision of a Junghans J80/12 with the black dial.
Hour and minute hands are questionable original. It already is, however, the second watch that I see with exact that hand variant. Maybe the watch was but delivered from the factory that way.
Again, I find it difficult in some caliber allocation. With the above list I tried to provide some clarity on the different caliber and their designations.
The movements were produced at the same time with or without divided wheel bridge. There are versions with 7, 11, 13, 15, 16 and 17 jewels.
There's caliber Junghans J80 with various imprints on the bridge: J80S; J80M (was probably Meister).