Safekipedia

Quartz clock

Adapted from Wikipedia · Adventurer experience

A close-up of a quartz watch showing the time.

Quartz clocks and quartz watches are special kinds of timepieces that use a tiny piece of quartz crystal to keep very accurate time. Inside these clocks, an electronic part called an oscillator is controlled by the vibrations of the quartz crystal. These vibrations happen at a very steady rate, which helps the clock keep perfect time.

Circuit board of an e block from a chronograph-wristwatch. The quartz crystal oscillator can be seen on right.

Because of this clever use of quartz, quartz clocks are much more accurate than older mechanical clocks. They can tell time much better.

When digital electronics became popular in the 1980s, making these clocks smaller and cheaper, quartz timekeepers became the most common way people keep track of time. Today, you’ll find them not just in wall clocks and wristwatches, but also in computers and many other devices that need to know the time.

Explanation

Disassembled analog quartz clockwork; quartz crystal oscillator (top left), Lavet-type stepping motor (left) with a black rotor sprocket and connected white and transparent gears (right). These gears control the movement of the second, minute and hour hands.

Quartz clocks and watches use a special crystal called quartz to keep time. When electricity passes through quartz, it vibrates at a steady rate. This helps the clock stay very accurate.

Inside the clock, a tiny piece of quartz shakes back and forth many times each second. This shaking creates a signal that the clock uses to count seconds, minutes, and hours. Most quartz clocks shake the quartz 32,768 times each second. This number is special because it is a power of two, which makes it easy for the clock’s electronics to count time. This helps the clock keep good time even when the temperature changes.

Mechanism

Picture of a quartz crystal resonator, used as the timekeeping component in quartz watches and clocks, with the case removed. It is formed in the shape of a tuning fork. Most such quartz clock crystals vibrate at a frequency of 32768 Hz.

Quartz clocks use a tiny piece of quartz that shakes back and forth very quickly. This shaking happens exactly 32,768 times every second. This helps the clock keep very accurate time. The quartz piece is usually shaped like a small tuning fork and is very small. Because of this precise shaking, quartz clocks are much more accurate than older clocks.

Accuracy

Quartz clocks and watches are very good at keeping time because they use a special piece of quartz that vibrates in a steady way. This helps them stay more accurate than older clocks. A good quartz watch or clock might only be off by about 15 seconds over 30 days, which means it could lose or gain less than half a second each day.

Temperature can affect how well a quartz clock keeps time, but designers have smart ways to handle this. Watches are often made to work best when worn on a person’s wrist, using body heat to stay steady. Some very accurate clocks can keep time within just a few seconds all year. Special designs and tools help make sure these clocks stay precise, even when the temperature changes a lot.

Quartz crystal aging

Quartz crystals used in clocks are made in very clean places and kept safe in special sealed containers. Even so, the time kept by these crystals can change a little over time. This change, called aging, is usually smaller than changes caused by temperature.

Things like stress, losing the seal on the container, or getting dirty can make the crystal’s time change a bit. Most of these changes happen in the first year the crystal is used, and then they slow down. Some crystals can be treated with heat before they are put in clocks to make them age faster. This helps keep the clock more accurate for longer. Better clocks often use crystals that have been treated this way.

Chronometers

Quartz chronometers are used to keep very exact time. They often have a special crystal oven to keep the crystal at the same temperature. Some can check themselves and use "crystal farms" to find the best average time from many measurements.

External magnetic interference

Analog quartz clocks use special motors that work with a magnetic field. Strong magnets nearby can bother these motors. This might make the clock hands stop, move too fast, or even go backward. Moving the clock away from the magnet usually helps.

Digital quartz clocks are usually safe from everyday magnets because they don’t use these motors. But very strong magnets, like those in MRI machines, can harm quartz clock parts.

History

Quartz was discovered to have special properties in 1880. In 1921, the first quartz crystal oscillator was made. In 1927, the first quartz clock was created. It used a quartz crystal to keep very accurate time.

In the 1930s and 1940s, quartz clocks were used in labs for exact time measurements. In the 1960s, the first quartz watches were made. These watches were expensive at first, but they became cheaper and more common as technology improved. By the 1980s, quartz clocks and watches were used in many everyday items like kitchen timers, alarm clocks, and watches. Today, quartz timepieces are very accurate and need little care because they have very few moving parts.

Four precision 100 kHz quartz oscillators at the US Bureau of Standards (now NIST) that became the first quartz frequency standard for the United States in 1929. Kept in temperature-controlled ovens to prevent frequency drift due to thermal expansion or contraction of the large quartz resonators (mounted under the glass domes on top of the units) they achieved accuracy of 10−7, roughly 1 second error in 4 months.

Early quartz clocks for consumers

One of the first experimental quartz controlled clocks, built by Warren Marrison at Bell Labs in 1927. A vacuum tube oscillator controlled by the 100 kHz quartz crystal (under dome at top) is divided down by vacuum tube counters and runs the synchronous clock on front. Accuracy was 0.01 second per day

First European quartz clock for consumers "Astrochron", Junghans, Schramberg, 1967

First quartz wristwatch movement, Caliber 35A, Seiko, Japan, 1969

Images

An Omega Constellation Megaquartz chronometer, a precise timekeeping device used by the French Navy for navigation at sea.
A colorful wooden clock showing the time with hour, minute, and second hands.
A close-up of a quartz watch’s inner workings, showing parts like the battery, oscillator, and motor that help tell time.
A modern titanium wristwatch with Eco-Drive technology, featuring a chronograph and world time functions.
The first European consumer quartz clock called 'Astrochron' made by Junghans in 1967.
A wall clock with hour and minute marks, displayed in a sunny conservatory.
The first quartz wristwatch movement, introduced by Seiko in 1969, which revolutionized timekeeping with its accuracy.

Related articles

This article is a child-friendly adaptation of the Wikipedia article on Quartz clock, available under CC BY-SA 4.0.

Images from Wikimedia Commons. Tap any image to view credits and license.