Valjoux is not a watch brand: it's an ébauche manufacture founded in Les Bioux, in the Vallée de Joux, that for nearly a century supplied chronograph movements to practically every major watchmaking house. From the Valjoux 23 of 1916 to the 7750 of 1974, this line of calibers defined the architecture of the modern mechanical chronograph more than any other manufacturer.
The Valjoux 23 is the starting point. Thirty-eight millimeters gross diameter — no, wait: 29.5 mm by 5.8 mm thick — column wheel with nine pillars, large balance, central Y-shaped bridge. From 1916 to 1974, adopted by Patek Philippe, Audemars Piguet, Vacheron Constantin. In 1938 the Valjoux 72 was born, a direct derivative of the 23 with the addition of a 12-hour totalizer: three counters, manual winding, 18,000 hourly beats until 1960, then updated to 21,600 in the 726 caliber. The 72 equipped Heuer, Rolex, Tudor and dozens of smaller houses. It was the standard engine of quality chronographs in those years.
Parallel to this lived less well-known but technically interesting variants. The Valjoux 88 added moon phase and triple calendar to the 72. The Valjoux 65, sixteen lines, was used by Eberhard as the basis for its flyback, renamed caliber 16000. The V23 family — with variants 234, 235, 236 and 237 — offered flyback and calendar in combinations that are rather rare on the secondary market today. The Valjoux 92 is immediately recognizable by its oscillating pinion, which commands the minute totalizer: a constructive detail that collectors learn to identify quickly.
In 1974 ETA, already part of the ASUAG Group like Valjoux, introduced the 7750: automatic chronograph, rotor winding, cam activation instead of column. The choice of cams was pragmatic — robustness, ease of service, production cost — not a technical compromise. The system works well, even though purists still prefer the column wheel for the fluidity of transitions. From the 7750 derive the 7751 with full calendar, the 7753 with counters at 3-6-9, and the more recent A05 that returns to that symmetrical layout. Sellita built its own SW510 on the same architecture. Joux-Perret with the L111 followed a similar evolutionary path. Chinese clones like the SL4617 by Liaoning Peacock replicate the 7750 scheme for the entry market.
From the bench I've seen pristine Valjoux 72s after sixty years of service and worn-out 7750s after ten. The difference often lay in the owner's care, not in the caliber.