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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.

A typical application for high capacitance, high voltage capacitors is a bulk filter capacitor shown in Figure 1 in a bipolar transistor totem pole configuration high voltage, high capacitance MLCCs are commonly used as input capacitor filters.

To obtain the required capacitance and high voltage rating the MLCCs are often placed in parallel or stacked vertically. This requires careful soldering and attachment processing, due to the larger case sizes required for the application. The basic function of the input capacitor filter is to hold up the rectified power bus line voltage as well as for filtering common mode noise.

Common mode noise flows asymmetrically through both input lines. The current into the load is supplied by the input filter capacitor bank rather than from the power supply, until the point at which the input voltage again equals the voltage across the filter capacitor, see wave forms in Figure 2.

A quartz crystal resonator depends on the piezo-electric effect to work. This effect converts a mechanical stress in a crystal to a voltage and vice versa. In this way the piezo-electric effect converts the electrical impulses to mechanical stress which is subject to the very high Q mechanical resonances of the crystal, and this is in turn linked back into the electrical circuit.

The quartz crystal can vibrate in several different ways, and this means that it has several resonances, all on different frequencies. Fortunately the way in which the quartz crystal blank is cut from the original crystal itself can very significantly reduce this. In fact the angle of the faces relative to the original crystal axes determines many of its properties from the way it vibrates to its activity, Q, and its temperature co-efficient. There are three main ways in which a crystal can vibrate: longitudinal mode, low frequency face shear mode, and high frequency shear. A cut known as the AT cut used for most crystals used in traditional radio and electronics circuits uses the high frequency shear mode.

Vibrational modes of a quartz crystal resonator
(For the sake of clarity, the movements have been greatly exaggerated)

A transmission line arrester also known as a transmission line surge arrester is any arrester that is applied out on the transmission line to reduce the possibility.

The resulting wave when an electrical variation in a circuit such as a transmission line takes the form of translation of energy along a conductor, such energy being always equally divided between current and potential forms. The traveling waves propagate at close to the speed of light and can generate surges at 2-4 times the initial impulse under certain circumstances.

Impulse protective levels of an arrester:

a) Fast front protective level: The highest of either the steep current residual voltage or the front-of-wave impulse spark over voltage.

b) Standard lightning impulse protective level: The highest of the residual voltage at nominal current or 1,2/50 lighting impulse spark over voltage.

c) Switching impulse protective level: The highest of either the maximum residual voltage for the specified switching current or the specified switching impulse spark over voltage.

Kingtronics is a manufacturer of Trimming Potentiometer. Trimming potentiometers are Kingtronics' first products. On Kingtronics' trimming potentiometers body, we mark "King" due to insufficient space. “Kingtronics” and "Kt" are our brand too. So, Kingtronics trimmers, Kingtronics potentiometers, King trimmers, and King potentiometers all mean potentiometers which produced by Kingtronics International Company.Our products are well crossed to Bourns Brand parts. We offer Kingtronics potentiometers (with Kt Mark trimming potentiometer) include following part number: RKT-3006, RKT-3266, RKT-3296, RKT-3299, RKT-3323, RKT-3329, RKT-3362, RKT-3386, RKT-3318, RKT-3306, RKT-3309, RKT-065, RKT-105H, RKT-C3305, RKT-3361, RKT-3540S, RKT-3590. Our trimming potentiometers are RoHS compliant.

Now Kingtronics offer Bourns equivalence. If you want more details , please visit website:www.kingtronics.com  for full specification.

If you have any inquiry about Trimming Potentiometer , pls contact info@kingtronics.com.

Welcome to check our price!

Application range:

Peace project(police),telecom "global E-eye"(telecom),road monitoring(police), Community Monitoring(building management), monitoring of environment(environment protection),expressway monitoring, etc.

System specification:

The lightning protection of monitoring system of CCTV is relatively complicated firstly we should understand the main reason why the monitoring system was damaged by the lightning and the possible lightning invaded route, specially, the outdoor monotoring equipment suffer from serious damage of lightning. only analysis on basis of the reason of damage, research and discussion on the laying, shield and earthing mode of signal and power line, the lightning protection device of monitoring system device can be selected and used accurately.

The TV monitoring systemis consisting of three parts as below:

1,The former part: composed of monochrome (colour television) vidicon, len, holder, hood , bracket, etc.

2, transmission part:coaxial-cable,wire,Multi-core wire,fibre,which transmiss video,audio or control signal by way of overhead in air,burial under ground or wall following laying.

3, computer roomterminal part: composed of matrix, monitoring device, hard disk video recorder,etc.

The equivalent series resistance is the resistive element (R1) of the quartz crystal equivalent circuit. (see Equivalent Circuit below) This resistance represents the equivalent impedance of the crystal at natural resonant frequency (series resonance) ESR is measured by a Crystal Impedance (CI) meter.

ESR values are generally stated as maximum values expressed in ohms. The ESR values vary with frequency, mode of operation, holder type, crystal plate size, electrode size, and mounting structure.

It is worth noting that the ESR value at a given frequency for an AT- strip crystal design is generally higher than that of the standard (round blank) design. This becomes more significant at lower frequencies. When transitioning from a series resonant through-hole HC-49/U type crystal to a smaller surface mount type utilizing an AT-strip crystal, some consideration may be given to the difference in the ESR values produced by different cuts.

The ESR becomes critical when resistance values reach a point were the oscillator circuit cannot adequately drive the crystal. Sluggish start-up or unwanted modes of operation may result.

Equivalent Circuit:

The equivalent circuit (shown in Figure A) depicts electrical activity of a quartz crystal unit operating at its natural resonant frequency. The shunt capacitance (Co), represents the capacitance of the crystal electrodes plus the capacitance of the holder and leads. R1, C1, and L1 compose the "motional arm" of the crystal, and are referred to as the motional parameters. The motional inductance (L1) represents the vibrating mass of the crystal unit. The motional capacitance (C1) represents the elasticity of the quartz, and the resistance (R1), represents bulk losses occurring within the quartz.