How Quartz Watches Work

February 18, 2018

Clock | Kawayee

The clocks that use Quartz need hardly any moving components. That's why it's currently used in even the most expensive timepieces.It is so accurate and reliable that clocks put Quartz very prominently, as a selling point.

How Quartz Watches work

Quartz Crystals

The trouble with a pendulum or ordinary watches is that you will have to constantly wind them. If you forget, they will stop and you would have no idea what time it is. Another difficulty with pendulum clocks is that they depend on gravity, which varies slightly in different parts of the world. That means a pendulum clock will tell time differently at high altitudes than at sea level! Pendulums also change in length as temperature changes. It expands on warm days and contracts on cold days, which makes them even less accurate.

Quartz watches solve all these problems. They are battery powered and use very little electricity. This means the battery can often last several years before you need to replace it. They are also a lot more accurate than pendulum clocks. Quartz watches work in a very different way than pendulum clocks or ordinary watches. They still have gears inside them to count the seconds, minutes, and hours and sweep the hands around the clock face. However, the gears are regulated by a small crystal of quartz instead of a pendulum or a moving balance wheel. Gravity doesn't affect it so a quartz watch will tell the time just as well when you are climbing Mount Everest as it does when you are at sea.

Quartz sounds exotic but it is actually one of the most common minerals on Earth. It is made from a chemical compound called silicon dioxide. You can find it in the sand and most types of rock. The most interesting thing about quartz is that it is piezoelectric. This means if you applied pressure on a quartz crystal, it would generate a small electric current. The opposite is also true. If you pass electricity through quartz, it will vibrate at a precise frequency.

Inside a quartz clock or watch, the battery sends electricity through the quartz crystal using an electronic circuit. The quartz crystal vibrates back and forth at a precise frequency of exactly 32768 times each second. The circuit counts the number of vibrations and halves them 15x to get to one per second. These pulses 

Inside a Quartz Watch

In theory, it works like this:

  1. The battery provides current to a microchip circuit.
  2. The Microchip circuit will make the quartz crystal oscillate 32768 times per second.
  3. The Microchip circuit will detect the crystal's oscillations and turns them into regular electric pulses, by halving it 15x to get one per second.
  4. Electric pulses drive miniature electric stepping motor. This converts electrical energy into mechanical power.
  5. Electric stepping motor turns gears.
  6. Gears move hands around the clock face to keep time.

Why do Quartz Watches gain or lose time at all?

If quartz is this magnificent, why are quartz watch not able keep time with perfect accuracy forever. Why does it still gain or lose seconds occasionally? The answer is that Quartz vibrates at slightly different frequencies at different temperatures or pressures. This affects its timekeeping ability by a tiny degree. In theory, if you keep a watch on your wrist all the time, it will keep time better than if you take it on and off. However, even if the quartz crystal could vibrate at a perfect constant frequency, the way it is mounted in the circuit, tiny imperfections in the watch, friction and so on can also introduce minute errors in timekeeping. All these effects are just enough to introduce an inaccuracy of up to a second a month in typical quartz clocks and watches.

Conclusion

That is as much as I am going to tell you. If you want to find out more, you might like to take a look at the following sources. Be warned that they are complex and hard to follow unless you have some knowledge of electronic engineering.

Quartz watches will need special care & maintenance, check out our article on it.

Be sure to check out our stylish collection of Quartz Watches

Further reading

General

  • Crystal oscillator: A detailed introduction from Wikipedia. This is one of those baffling Wikipedia articles likely to only make sense to people who know enough about the subject to write the article in the first place. 

History

  • The Evolution of the Quartz Crystal Clock by Warren A. Marrison, The Bell System Technical Journal, Vol. XXVII, pp. 510-588, 1948. This is a superb, fascinating, definitive, and detailed paper setting out the history of quartz timekeeping, written by one of its pioneers.[Archived via the Wayback Machine and available in various other formats from the Internet Archive.]
  • Modern developments in precision clocks by A. L. Loomis (Loomis Laboratory) and W. A. Marrison, IEE Electrical Engineering, Vol. 51, No. 2, February 1932. Another classic account from the archives by two of the key pioneers. (Subscription article electronically uploaded in 2013.)

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