Using the early work at Bell Labs, AT&T eventually established their Frequency Control Products division, later spun off and known today as Vectron International. With accuracies of up to 1 second in 30 years (30 ms/y, or 0.95 ns/s), quartz clocks replaced precision pendulum clocks as the world's most accurate timekeepers until atomic clocks were developed in the 1950s.

In 1928, Warren Marrison of Bell Telephone Laboratories developed the first quartz-crystal clock. In 1925, Westinghouse installed a crystal oscillator in its flagship station KDKA, and by 1926, quartz crystals were used to control the frequency of many broadcasting stations and were popular with amateur radio operators. Since broadcast stations were assigned frequencies only 10 kHz (Americas) or 9 kHz (elsewhere) apart, interference between adjacent stations due to frequency drift was a common problem. Prior to crystals, radio stations controlled their frequency with tuned circuits, which could easily drift off frequency by 3–4 kHz. Quartz crystal oscillators were developed for high-stability frequency references during the 1920s and 1930s. Other early innovators in quartz crystal oscillators include G. Cady built the first quartz crystal oscillator in 1921. Nicholson at Bell Telephone Laboratories, although his priority was disputed by Walter Guyton Cady. The first crystal-controlled oscillator, using a crystal of Rochelle salt, was built in 1917 and patented in 1918 by Alexander M. Paul Langevin first investigated quartz resonators for use in sonar during World War I. Piezoelectricity was discovered by Jacques and Pierre Curie in 1880. Very early Bell Labs crystals from Vectron International Collection Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.

However, in applications where small size and weight is needed crystals can be replaced by thin-film bulk acoustic resonators, specifically if ultra-high frequency (more than roughly 1.5 GHz) resonance is needed. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. As of 2003, around two billion crystals are manufactured annually. Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. Once a quartz crystal is adjusted to a particular frequency (which is affected by the mass of electrodes attached to the crystal, the orientation of the crystal, temperature and other factors), it maintains that frequency with high stability. The quartz oscillates at a stable resonant frequency, behaving like an RLC circuit, but with a much higher Q factor (less energy loss on each cycle of oscillation). A voltage applied to the electrodes on the crystal causes it to change shape when the voltage is removed, the crystal generates a small voltage as it elastically returns to its original shape. However, other piezoelectricity materials including polycrystalline ceramics are used in similar circuits.Ī crystal oscillator relies on the slight change in shape of a quartz crystal under an electric field, a property known as inverse piezoelectricity. The most common type of piezoelectric resonator used is a quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. Nicholson, Walter Guyton CadyĪ crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. A miniature 16 MHz quartz crystal enclosed in a hermetically sealed HC-49/S package, used as the resonator in a crystal oscillator.Īlexander M.

10 foot quartzcrystal