Stories, craft
& keeping time.

Power

Wound mainspring

Timing

Balance & hairspring

I think of a mechanical watch as stored energy being released with remarkable patience. Winding tightens a mainspring; as it unwinds, it drives gears and hands. The balance wheel and hairspring oscillate, while the escapement meters out the motion and keeps that oscillation going.

Manual winding puts energy in through the crown. An automatic movement uses a rotor moved by the wrist to wind the same kind of spring; many also allow hand winding. What interests me is how much precision emerges from this small assembly of moving parts.

“Automatic” describes how the spring is wound, rather than a different timekeeping principle.

Power

Electrical energy

Timing

Quartz oscillator

Quartz appeals to me as a beautifully direct use of an oscillator. A circuit maintains and counts the vibrations of a quartz crystal, commonly at 32,768 times per second. Dividing that frequency down gives the watch its timing signal.

In a conventional analogue quartz watch, a battery supplies the electricity and a stepper motor moves the hands through gears. A digital display can use the same timing principle. The familiar one-second tick is a design choice in many movements, rather than the definition of quartz itself.

The crystal supplies the timing reference; the battery supplies the energy.

Power

Light → rechargeable cell

Timing

Quartz oscillator

A solar quartz watch adds a useful answer to the power question. A solar cell converts light into electricity and stores it in a rechargeable cell. The quartz oscillator still does the timekeeping, and the stored charge lets the watch run when it is dark.

I like the practicality of using an everyday energy source in such a small device. “Solar” tells us how the watch is charged; it does not mean the hands are driven directly by sunlight. Light exposure and the available power reserve still matter.

A different way to replenish electrical energy, with quartz timing underneath.

Power

Rotor → generator → rechargeable cell

Timing

Quartz oscillator

Seiko’s Kinetic is an interesting meeting of moving machinery and electronic timekeeping. Movement of the wrist turns an oscillating weight, which drives a small electrical generator. The resulting energy is stored in a rechargeable cell and powers a quartz movement.

The rotor can make it sound similar to an automatic mechanical watch, but it is doing a different job: generating electricity rather than winding a mainspring. That distinction is the part I find most useful when explaining Kinetic.

The wearer supplies motion; a quartz oscillator supplies the rhythm.

Power

Wound mainspring

Timing

Quartz reference & electromagnetic brake

Spring Drive is especially interesting to me because it separates the source of power from the way that power is regulated. A mainspring drives the hands through gears. A rotating glide wheel also generates the tiny amount of electricity needed by a quartz oscillator and an integrated circuit, without a battery.

The circuit compares the glide wheel’s speed with the quartz reference and controls an electromagnetic brake. This replaces the conventional balance-and-escapement regulation and gives the seconds hand its continuous glide. Mechanical, electrical and electromagnetic processes all have a distinct role.

The spring drives the hands; the quartz-controlled brake regulates their pace.