SW501 a

	Brand:	Sellita
	Family:	Sellita SW500 Family
	Height:	7.90 mm
	Jewels:	25
	Reserve:	48 hours
	Frequency:	28,800 A/h
	Winding:	Automatic, Central Rotor Automatic Winding
	Diameter:	30.00 mm (13.25 ligne)
	Complications:	2-Button, Cam Switching Chronograph, Chronograph, Date, Day, Hacking Seconds, Quick Date Correction
	Hands:	12 Hour Chronograph Hand at 6:00, 15 Minute Chronograph Hand at 12:00, Central 60 Second Chronograph Hand, Central Hour Hand, Central Minute Hand, Date Window at 3:00, Day Window at 3:00, Small Seconds Hand at 9:00

Distinguishing Technical Characteristics
Central-Rotor Automatic Clockwise Balance Cock Screw Regulator Balance at 1:30 Central Rotor
Production: 2017 – Current
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

Sellita Cal. SW501 a is a clone of the ETA/Valjoux 7750 automatic chronograph with day and date. In production since 2009, Cal. SW500 is used by a wide variety of manufacturers and is sometimes even referred to as “7750”. One notable difference is the use of an eccentric screw regulator rather than the Valjoux index system. The “501 a” name has only been seen since 2017, though the availability of a 15 minute day-and-date SW500 movement from Sellita might pre-date this name.

This movement features the classic Valjoux 7750 subdial arrangement with running small seconds at 9:00, a 12 hour chronograph counter at 6:00 and a 15 minute chronograph counter at 12:00. Day and date windows are placed at 3:00.

Sellita SW500 and SW600 Technical Information

The Sellita SW500 and SW600 movements are based on the Valjoux 7750 design, itself based on the Valjoux 7733 and Venus 188. This movement is known for durability and flexibility and is used as a base in many watches, from entry-level chronographs to the famous IWC “Il Destriero Scafusia” grande complication. It is a large and relatively thick movement, measuring 13.25 ligne (30.00 mm) in diameter and 7.90 mm thick.

Although based on a classic design, the modern SW500 and SW600 is robust and full-featured. It operates at 4 Hz (28,800 A/h) with an efficient uni-directional central winding rotor. The day and date wheels feature crown-operated quick correction and a stop seconds (“hacking”) feature is included. The base movement has the famous Valjoux 6-9-12 subdial layout with small seconds at 9:00, but many Sellita versions have other subdial designs.

One major differentiator for the Sellita movements is the use of an eccentric screw for regulation rather than the traditional Valjoux articulated index.

Sellita SW500/SW501 variants

	Day and Date	Date Only	No Date
30 Minute Counter	SW500 a	SW500 b	SW500 c
15 Minute Counter	SW501 a	SW501 b	SW501 c