Switzerland / USA · Developed 1950s; released 1960
Tuning-Fork Watch (Accutron)
Partially verifiedThe first commercially successful electronic watch, bridging mechanical and quartz eras.
A transistor-driven tuning fork vibrating at 360 Hz drives the hands through a tiny index wheel, giving the characteristic hum.
How to verify this yourself
Search the relevant national patent office archive (Espacenet covers most European and US specifications) by inventor name and date range; confirm the number from the specification itself, not secondary sources.
Manufacturers known to have used it
- Bulova
Diagram
Sources & references
- Smithsonian National Museum of American History, Accutron holdings
- Bulova published history
Where sources disagree, the disagreement is stated rather than resolved silently.