ETA 2894-2
Produced by ETA (Swatch Group) since 1996
automatic modular construction with ETA 2892 base movement and chronograph plate, 28,800 bph, 28 mm diameter, 6.1 mm height, 37 jewels, 47 h power-reserve, lever/cam design
very common, often used in mid-priced models with a Tricompax (3,6,9) helper-dial outlay, due to the modular construction, crown and pushers are not on the same line
Examples of watches that use this movement: Omega automatic Speedmasters with helper dials at 3,6 and 9. Chopard Mille Miglia chrono, Ulysse Nardin Marine Chronograph, Hublot Navy, Girard Perregaux "Pour Ferrari"
THE VALJOUX 7750 CHRONOGRAPH
BY WALT ODETS
If there is a single movement ubiquitous in modestly-priced contemporary chronographs, it is the Valjoux 7750. Introduced in 1974--five years after the famed Zenith El Primero automatic--the movement has been supplied in both 21,600 and 28,800 beat versions. It uses an automatic-winding module attached to the top of the movement, winding in one direction by means of a single double-click wheel. Initially using 17 jewels, current versions run in 25. The 7750 is 13.25 ligne (30 millimeter) design, 7.9 millimeters thick.
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Hope this answers it for you. 2894 is newer, slimmer, more jewels - basically a module on a 2892 which is a wonderful movement! I would say the 2894 is more refined.
The VJ 7750 is an amazingly reliable movement, though.
Both are excellent. It's a U-Pik-Em