Clock Drive Rotor

Wall-clock rotor (approximately 8 mm long). © Eugene Brennan

The mechanism (also called the movement) or working parts in a quartz battery clock is a bit simpler than in a traditional wind-up clock.

At the heart of the clock is a quartz oscillator, which generates a pulse every second. An oscillator is a device that does something regularly, like a pendulum that swings back and forth, a tuning fork vibrating, a string on a guitar or the air in an organ pipe. All these are mechanical oscillators, but there are also electronic oscillators.

An electronic oscillator generates a voltage signal that repeats itself at a set frequency. In the case of the oscillator in a clock, this runs at several thousand hertz or cycles per second. An electronic component called a quartz crystal sets the frequency of the oscillator to about 32,768 Hz with a high degree of accuracy. The frequency is divided down and reduced so that it eventually becomes 1Hz or 1 cycle per second. The output of the oscillator drives an electromagnet that acts on a tiny magnetic rotor, flipping it half a turn every second. The rotor has gear teeth that mesh with a train of other gear wheels and this eventually turns the hands of the clock.

Quartz clock mechanism. © Eugene Brennan

A closer look. © Eugene Brennan