Attiny85 controlled watch winder for self-winding mechanical watches

Abstract

Abstract In mechanical self-winding movement, the center-anchored Rotating Weight rotates about its axis with physical motions of the hand. It thereby winds the mainspring only when worn and stops during lay-offs. A watch winder re-creates the physical motions to maintain the beat in the caliber, when not worn. The paper proposes a residential tourbillon watch winder for self-winding mechanical calibers. The main objectives of this paper are to minimize the working time of the winder and consequently optimize its power consumption. A significant trade-off between the winding and unwinding ratios of the mainspring is ensured, maintaining a higher former ratio using a single-phase 9 RPM Permanent Magnet Synchronous Motor. The proposed model states the sufficiency of the winder to work only for 60% of the time. The model uses Watchdog timer to rekindle Attiny85 Microcontroller from sleep mode for scheduling the working time of the winder. The disclosed model is deployed to a Seiko (7S26A) caliber and a Citizen (8200A) Caliber for a period of 26 days to validate the working. The results show that the proposed model with the Seiko caliber requires 41.1 h for winding while the commercial models require 70.99 h. Similarly with the Citizen Caliber, the proposed watch winder requires only 28.8 h which is 21.11 h less than the time required by commercial models.

Keywords

• Attiny85
• Watchdog timer
• Synchronous motor
• Watch winder
• Self-winding calibers
• Gear ratio