Felsa

Felsa was a Swiss watch movement manufacturer founded in Grenchen in 1918 that developed the pioneering Bidynator series of automatic movements with a patented bi-directional winding rotor. Designer Friedrich Meyer invented the mechanism, patented around 1946-1947, enabling the rotor to wind the mainspring in both directions - a first that revolutionized automatic watches and became an industry standard. The Bidynator debuted with Cal. 410 (men's) and Cal. 380 (ladies') in 1942, though WWII delayed full production. The refined Cal. 690 followed in 1947, offering a 43-hour power reserve, with variants like 691, 696, and 698 produced through the 1960s. Meyer's innovation outperformed earlier uni-directional rotors by using a clever lever system that engages different gears based on rotor direction. Felsa supplied movements to brands like Fluva Genève, Enicar, Bulova, Angelus, and Engleton. The company's robustness and design led Ebauches SA to specialize Felsa in automatics alongside ETA and A. Schild. Felsa joined Ebauches SA in 1928, which became part of ASUAG in 1931. Ebauches SA merged into ETA between 1979-1985, absorbing Felsa into what is now the modern ETA, part of the Swatch Group.