Since the early 1970ies, Bifora (Bidlingmaier in Schwäbisch Gmünd, Germany) also offered battery-powered movement, the smallest of them was the caliber B10, a ladies' watch movement with a diameter of 8 1/4 lignes. It was clear, that native electromechanical movements are just an intermediate step to quartz movements, and so in 1973 already, the first inhouse quartz movement was released, the caliber B12, which based largely on the electromechanical predecessors (B10 and B11).Video on YouTube
In place of the balance, you find a rocking lever, which noisily changes once per second its position and advances the gear train.
As you can easily see, the whole construction is quite complicated, additionally, it uses an early long quartz (MTQ-22) and a large trimmer capacitor, so that these movements were not produced very long.
It’s noteable, that the gear train uses not much space, but the battery (Type 313) more.
In terms of features, this movement has got a hacking second, a day-date indication and a date quickset mechanism.
Since this movement is a very fragile construction and still in working condition, it was not taken apart, and so the dial side cannot be shown, since also the very flat second hand would have been harmed beyond repair. Those who are interested on details, should definitely take a look to the richly illustrated article of the Bifora B12 at CrazyWatches.pl.
In the lab
The specimen shown here is fully working, but loses a few seconds per day, in sum about one minute per week. This can be either to a dry movement (no wonder, after more than 40 years) or an aged quartz crystal, for which there hardly will exist spare parts and more.
For archiving purposes, this doesn't matter, since the movement runs in general.
|Size:||13''' (measured: 29,3mm)|
|Number of jewels:||5|
|Construction type:||pillar construction|
|Production period:||1973 - 197?|
Flume: K3N1 1|
|Mentioning in literature (years):||1975|