Kingtronics Blog

Crystal oscillators are used in a variety of applications. In some instances crystal oscillators may be used to provide a cheap clock signal for use in a digital or logic circuit. In other instances they may used to provide an RF signal source. In view of the fact that quartz crystals offer a very high level of Q and they are stable, crystal oscillators are often used in oscillator circuits to provide stable, accurate radio frequency signals.

There is a great number of different types of circuit that can be used for crystal oscillators, each one having its own advantages and disadvantages. One of the most common circuits used for crystal oscillators is the Colpitts configuration as shown below.

In this configuration, the crystal operates in a parallel mode. When running in this mode, the crystal should be presented with a load capacitance to operate on its correct frequency. This load capacitance is specified with the crystal and is typically 20 or 30 pF. The crystal oscillator circuit will be designed to present this capacitance to the crystal. Most of this will be made up by the two capacitors C1 and C2, although the remaining elements of the circuit will provide some capacitance.

Functionally, Zener diodes are used as regulators, limiters and to control output switching. When used as regulators, the constant reverse voltage of Zener diodes allows for the regulation of output voltage against both variations in the input voltage from an unregulated power supply and from variations in the load resistance. The current traveling through Zener diodes changes to keep the voltage within the threshold of Zener action and the maximum power it can dissipate. Zener regulators tend to most efficiently function when constant voltage is applied, especially when used in conjunction with regulated power supplies, and for limiter applications.

Zener limiters are constructed with two opposing Zener diodes. Each individual diode can limit one side of a sinusoidal waveform to Zener voltage while keeping the other side near zero. When the two opposing Zener diodes are paired, the waveform is limited to Zener voltage on both polarities.

Zener diodes are also used to control output switching. In this application, Zener diodes switch the output between voltages. This is determined by the changes in input voltage through the diode. The output circuit amounts to a Zener regulator that switches from one Zener voltage to the other on transition through the Zener diode.

Kingtronics supply all kinds of Zener Diodes BZV55C & ZMM55C, http://www.kingtronics.com/pdf/BZV55C.pdf has detailed introduce Zener Diode’s features and types.

Multilayer ceramic capacitors consist of electrodes, the interleaved ceramic dielectric and the external terminal connectors. The capacitance is given by the description:

A = Electrode area
n = Number of active layers
d = Distance between electrodes
εr = Dielectric relative
ε0 = Dielectric constant

Whilst the values “A x n” and “d” are respectively determined by the production process the dielectric constant is a function of the ceramic material used.

Tantalum capacitors are manufactured from a powder of pure tantalum metal pressed to form a slug around a tantalum wire and subsequently vacuum sintered at high temperature. The resulting slug, although of high mechanical strength and density, is also highly porous giving a large internal surface area. This forms the positive "plate" of the capacitor. A dielectric layer of tantalum pentoxide is anodized on the surface of the tantalum anode, the cathode is formed by layers of manganese dioxide. Electrical contact is established by the deposition of carbon onto the surface of the "slug". The cathode connection is then made by means of conductive contact to a lead frame. Packaging is carried out to meet individual specification and customer requirements.

The tantalum capacitors must be used in such a conditions that the sum of the working voltage and ripple voltage peak values does not exceed the rated voltage.

Ceramic capacitors have a variety of different ceramic dielectrics as the basis of the capacitor. Ceramic dielectrics are made from a variety of forms of ceramic dielectric. The exact formulas of the different ceramics used in ceramic capacitors vary from one manufacturer to another but common compounds include titanium dioxide, strontium titanate, and barium titanate.

The actual performance of the ceramic capacitors is highly dependent upon the dielectric used. Using modern dielectrics, very high values are available, but it is also necessary to check parameters such as the temperature coefficient and tolerance. Different levels of performance are often governed by the dielectric used, and therefore it is necessary to choose the type of dielectric in the ceramic capacitor.

Kingtronics www.kingtronics.com  produce and sell Ceramic Capacitors all types. Multilayer Ceramic Capacitors are available in four series in Kingtronics: AKT Series Axial Lead, Axial MLCC Capacitors(Multilayer Ceramic Capacitors), MKT Series Radial MLCC Capacitors(Multilayer Ceramic Capacitors), LKT Series Chip MLCC.

Tantalum SMD capacitors are widely used to provide levels of capacitance that are higher than those that can be achieved when using ceramic capacitors. The capacitor technology that is used within SMD tantalum capacitors is based on the solid tantalum capacitor technology. This is robust and enables very small capacitors to be made.

For many years tantalum capacitors were used in SMD applications because electrolytic capacitors were not able to survive the high temperatures of the soldering process. Now that electrolytic capacitor technology has been developed to withstand the soldering process, these capacitors are now also widely used. Despite this, the other advantages of tantalum capacitors are employed in many circuits, and they are still used in vast quantities.

There are many different types of diodes that are available for use in electronics design. Different semiconductor diode types can be used to perform different functions as a result of the properties of these different diode types.

Semiconductor diodes can be used for many applications. The basic application is obviously to rectify waveforms. This can be used within power supplies or within radio detectors. Signal diodes can also be used for many other functions within circuits where the "one way" effect of a diode may be required.
 
Kingtronics sell many different types of diode, in our website we have a full products list of diode & rectifiers, please go to Products link and have a view.

There is a common intermediate configuration, when both electrodes are located on the same probe, but the return electrode is much larger than the active one. Since current density is higher in front of the smaller electrode, the heating and associated tissue effects take place only (or primarily) in front of the active electrode, and exact position of the return electrode on tissue is not critical. Sometimes such configuration is called sesqui polar, even though the origin of this term in Latin (sesqui) means a ratio of 1.5

Kingtronics (www.kingtronics.com ) sell 2-Electrode arresters and 3-Electrode arresters. Surge arresters are designed to protect electrical equipment from damaging effects of spikes and transients caused by lightning, utility switching, isolation arcing, electrical motor cycling, or any other sudden change in electrical power flow on incoming AC power lines.

A common element in electronic devices is a three-terminal resistor with a continuously adjustable tapping point controlled by rotation of a shaft or a knob. These variable resistors are known as potentiometers when all three terminals are present, since they act as a continuously adjustable voltage divider. A common example is a volume control for a radio receiver.

Accurate, high-resolution panel-mounted potentiometers (or "pots") have resistance elements typically wirewound on a helical mandrel, although some include a conductive-plastic resistance coating over the wire to improve resolution. These typically offer ten turns of their shafts to cover their full range. They are usually set with dials that include a simple turns counter and a graduated dial. Electronic analog computers used them in quantity for setting coefficients, and delayed-sweep oscilloscopes of recent decades included one on their panels.

Quartz crystals use the piezoelectric effect to convert the incoming electrical impulses into mechanical vibrations. These vibrations are affected by the mechanical resonances of the crystal, and as the piezoelectric effect operates in both directions, the mechanical resonances affect the electrical stimuli, being reflected back into the electrical circuit.

Today, quartz crystal filters can be designed with pass bands ranging from frequencies in the kilohertz region up to many Megahertz - with the latest technology this can rise to 100 MHz and more. However for the best performance and lowest costs the passband of the filter is generally kept to below about 30 MHz or so.