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Limited resources of natural quartz crystal suitable for direct electronic or optical use are available throughout the world. World dependence on these resources will continue to decline because of the increased acceptance of cultured quartz crystal as an alternative material; however, use of cultured quartz crystal will mean an increased dependence on lascas for growing cultured quartz.

Trends indicate that demand for quartz crystal devices should continue to grow, and consequently, quartz crystal production should remain strong well into the future. Growth of the consumer electronics market (for products such as personal computers, electronic games, and cellular telephones) will continue to drive global production. The growing global electronics market may require additional production capacity worldwide.

In the past several years, cultured quartz crystal was increasingly produced in the world, primarily in Asia. Electronic applications accounted for most industrial uses of quartz crystal; other uses included special optical applications.Virtually all quartz crystal used for electronics was cultured rather than natural crystal. Electronic-grade quartz crystal was essential for making filters, frequency controls, and timers in electronic circuits employed for a wide range of products, such as communications equipment, computers, and many consumer goods, such as electronic games and television receivers.

Quartz crystal is the best material for frequency-control oscillators and frequency filters in electronic circuits.

Kingtronics offers leaded quartz crystal HC49U, HC49S and SMD quartz crystal HC49SMD.If you want more details ,please visit website www.kingtronics.com for full specification.

Multi-layer ceramic chip (MLCC) capacitors are used quite often in dc-dc converter input and output filters. They have low ESR, low ESL, and low cost. They also have no major reliability problems associated with them.

All these properties make them suitable for power management applications. There are still, however, some issues to consider when using these capacitors in dc-dc converter circuits. Some ceramic capacitors can lose a lot of their value under certain conditions. This lost capacitance can degrade the transient response of a dc-dc converter, or it can even make the control loop of the converter unstable.

Telephone / fax / modem protection

Telephones, faxes and modems are equipped with sophisticated but sensitive electronics. Typical circuits used to protect them with surge arresters are shown in following Fig.

These arresters protect against common-mode interference voltages, i.e. surge voltages that appear in both lines to ground. In the event of an over voltage, the arrester protects both exchange lines by conducting the surge current away to ground.

Transducers

Potentiometers are also very widely used as a part of displacement transducers because of the simplicity of construction and because they can give a large output signal.

Computation

In analog computers, high precision potentiometers are used to scale intermediate results by desired constant factors, or to set initial conditions for a calculation. A motor-driven potentiometer may be used as a function generator, using a non-linear resistance card to supply approximations to trigonometric functions. For example, the shaft rotation might represent an angle, and the voltage division ratio can be made proportional to the cosine of the angle.

Tantalum capacitors are manufactured from a powder of relatively pure tantalum metal. The typical particle size is between 2 and 10 μm. Figure  below shows increasing surface area powders. Surface area is expressed in capacitance (C) in microfarads (µF) times voltage (V) in volts (V) per gram of powder (CV/g) Note the very great difference in particle size between the powders.

One advantage of remembering this layout for a bridge rectifier circuit is that it expands easily into a polyphase version in Figure below

Electronic-grade quartz crystal is single-crystal silica that is free from all visible defects and has piezoelectric properties that permit its use in electronic circuits for accurate frequency control, timing, and filtration. These uses generate practically all the demand for electronic-grade quartz crystal. A smaller amount of optical-grade quartz crystal is used as windows and lenses in specialized devices including some lasers.

More natural quartz crystal was consumed in electronic and optical applications until 1971, when cultured quartz crystal took the lead. Since that time cultured (synthetic) quartz has replaced natural crystal in practically all these applications. The use of natural quartz crystals for carvings and other gemstone applications continued; quartz crystals for this application are discussed in the Gemstones Annual Report of the U.S. Bureau of Mines.

Despite the fact that Schottky barrier diodes have many applications in today's high tech electronics scene, it is actually one of the oldest semiconductor devices in existence. As a metal-semiconductor devices, its applications can be traced back to before 1900 where crystal detectors, cat's whisker detectors and the like were all effectively Schottky barrier diodes.

The Schottky diode symbol used in many circuit schematic diagrams may be that of an ordinary diode symbol. However it is often necessary to use a specific Schottky diode symbol to signify that a Schottky diode rather than another one must be used because it is essential to the operation of the circuit. Accordingly a specific Schottky diode symbol has been accepted for use. This Schottky diode symbol is shown below:

Variable resistors used as potentiometers have all three terminals connected.

This arrangement is normally used to vary voltage, for example to set the switching point of a circuit with a sensor, or control the volume (loudness) in an amplifier circuit. If the terminals at the ends of the track are connected across the power supply then the wiper terminal will provide a voltage which can be varied from zero up to the maximum of the supply.

The equivalent series resistance (ESR) of a solid tantalum capacitor is frequency dependent. The curves of Figure 6 are typical of the capacitor values noted, with measurements being made by contacting lead wires 1/4 inch from the ends of the capacitor cases. Since ESR decreases with frequency, AC performance at higher frequencies is considerably better than would be predicted from the 120 Hz ratings.