For folks who are interested in the subject matter: electronic tuning fork movements, like the Accutron 214, are amazingly elegant bits of engineering. Both the time regulation and motive power are provided by a tuning fork (vs the balance wheel and mainspring), which is kept oscillating through electromagnetism (vs the escapement) in one of the first consumer applications of the transistor. The movement was designed and started being manufactured in the late 1950s.

Max Hetzel's patents are a good starting point - https://www.accutrons.com/tuning-fork-watch-patents