Clock oscillators are electronic circuits that are used to time certain events. They can be used to control the speed at which the second hand of a watch ticks. These devices can be made out of a number of materials, though the most common and most precise material is quartz crystal. These devices use an electronic stimulus to create a mechanical motion.
Applying an electrical current to a clock oscillator causes it to vibrate or oscillate at its natural frequency. The natural frequency of materials commonly used in these circuits is a narrow and stable one. The rigid oscillation frequency means that engineers can use the numerical information about that frequency when determining the timing of clock oscillators. The frequency can be used to mark seconds or other units of time using a simple mathematical formula and the known frequency of the device. Computers, radio transmitters, and radio receivers use clock oscillators to control timing.
Time can be measured using clock oscillators. The material of the oscillator, whether quartz, ceramic or another stable material, oscillates at a predictable rate when an electrical stimulus is applied to it. The natural frequency of the oscillator can change based on the shape, size and cut of the material, which means the oscillator must be tested and calibrated before use. Most clock oscillators used in watches are shaped like tuning forks.
The quartz crystal is the most common device used in clock oscillators because it has a very precise natural frequency. Quartz crystal is also not particularly reactive to chemicals, so very little change in the structure of the crystal happens over time, making quartz crystal oscillators accurate for a great number of years. Though temperature and pressure can affect the range of signals it will pick up, adaptations to the crystal and its circuit can lessen the effects of these external changes.
The principle used in clock oscillators was first discovered by the Curie brothers in 1880. Called the piezoelectric effect, the conversion of electricity into mechanical motion or the opposite — the inverse piezoelectric effect. This method of generating motion was much more stable than older models, which relied solely on mechanics. One of the first industries to embrace the concept of the piezoelectric effect was the watch industry, which switched from mechanical watches that required winding to crystal clock oscillators that kept time with very little degradation.