ETA Valjoux 7750

Speed1×

Rotor swings and winds the mainspring

00:00:00.0

At zero · press Start

Real time: the balance beats 8× a second, but the center wheel needs an hour per turn — the upper train barely moves. That is correct.

Space play / pauseE explode · R reset view · W wristS chrono start / stop · X resetEsc deselect

Technical sheet

ETA Valjoux 7750

The cam-operated automatic chronograph: small seconds at 9, counters at 12 and 6, day-date at 3.

Manufacturer: ETA (Valjoux), Swatch Group
Calibre: 7750
Type: Automatic chronograph (cam-operated, oscillating pinion), small seconds, 30-minute and 12-hour counters, day and date
Frequency: 4 Hz
Beat rate: 28,800 vph
Jewels: 25
Diameter: 30 mm
Power reserve: 54 h
Escape wheel: 20 teeth · 40 beats / rev
Balance amplitude (model): 280°

Features

Winding: Automatic, unidirectional rotor
Seconds: Small seconds at 9 o’clock
Calendar: Day and date
Hacking: Yes — seconds stop when the crown is pulled
Chronograph: Cam-operated, oscillating-pinion coupling
Counters: Central seconds · 30-minute counter at 12 · 12-hour counter at 6

Watches with this movement

Breitling Chronomat (1984)Valjoux 7750
Fortis F-2001 alarm chronograph (1997)7750 base with an alarm
IWC Da Vinci Perpetual Calendar Chronograph (1985)IWC 79261, 7750 base with a perpetual calendar module
IWC Doppelchronograph 3711Split-seconds development on a 7750 base (Richard Habring)
TAG Heuer Carrera Calibre 16 (2005 relaunch)TAG Heuer Calibre 16, 7750 base (later Calibre 16s use the Sellita SW500)

Going train

Arbor	Wheel	Pinion	True speed
Mainspring barrel	84	—	1 rev / 7 hours
Center wheel	80	12	1 rev / hour
Third wheel	75	10	8 rev / hour
Fourth (seconds) wheel	84	10	1 rev / minute
Escape wheel	20	7	12 rev / minute

Disclaimer

An approximation of the Valjoux 7750 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 25 jewels, typical 54 h power reserve (ETA; press figures range from about 42 to 48 h), Ø 30.00 mm (13¼ lignes), 7.90 mm height, unidirectional self-winding, cam-operated chronograph with oscillating pinion, small seconds at 9, 30-minute counter at 12, 12-hour counter at 6, day and date at 3 and stop-seconds are published figures. Tooth counts, wheel sizes, the positions and outlines of the bridges and the chronograph levers, cam, hammer and brake are an approximation (their geometry is not published); the tooth counts make the fourth wheel turn once a minute and the escape wheel match 28,800 vph. Parts are drawn larger than life and the stack is taller than the real 7.90 mm. The escapement and chronograph motions are kinematic models.

Sources