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The capacitance of certain capacitors decreases as the component ages. In ceramic capacitors, this is caused by degradation of the dielectric. The type of dielectric and the ambient operating and storage temperatures are the most significant aging factors, while the operating voltage has a smaller effect. The aging process may be reversed by heating the component above the Curie point. Aging is fastest near the beginning of life of the component, and the device stabilizes over time. Electrolytic capacitors age as the electrolyte evaporates. In contrast with ceramic capacitors, this occurs towards the end of life of the component.

Capacitors, especially ceramic capacitors, and older designs such as paper capacitors, can absorb sound waves resulting in a microphonic effect. Vibration moves the plates, causing the capacitance to vary, in turn inducing AC current. Some dielectrics also generate piezoelectricity. The resulting interference is especially problematic in audio applications, potentially causing feedback or unintended recording. In the reverse microphonic effect, the varying electric field between the capacitor plates exerts a physical force, moving them as a speaker. This can generate audible sound, but drains energy and stresses the dielectric and the electrolyte, if any.

The Decoupling capacitor is used to decouple the IC from the power source. The By-Pass capacitor reduces the trace length from the power source to a trace length from the IC to the decoupling capacitor ~ a reduction from many inches to less then an inch. A reduction of 20nH an inch in trace inductance is achieved by introducing a decoupling capacitor in between the IC and its power source. Assuming the power source is a regulator 12 inches away, and the by-pass capacitor is placed within an inch of the IC, the trace inductance is reduced from 240nH to 20nH.

Electronic capacitors are one of the most widely used electronic components. These electronic capacitors only allow alternating or changing signals to pass through them, and as a result they find applications in many different areas of electronic circuit design. Suntan supply a wide variety of types of capacitor including electrolytic, ceramic, tantalum, plastic, sliver mica, and many more. Each capacitor type is introduced in www.suntan.com.hk.

The choice of the correct capacitor type can have a major impact on any circuit. The differences between the different types of capacitor can mean that the circuit may not work correctly if the correct type of capacitor is not used.

Although the construction techniques and materials used to manufacture multilayer ceramic and tantalum capacitors are completely different, the basic applications still remain the same. Capacitors in the 0.1 - 22µF range are used mainly for digital circuit decoupling and filtering. Acting as local supplies of charge, capacitors assist power supplies in remaining at a constant DC voltage despite the continuous switching of digital signal circuitry. Capacitors also function as simple, single pole filters and can be used in conjunction with other devices (resistors and inductors) to create higher order filter circuits.

As much as tantalums and ceramics are both capacitors, they do have many different properties. The case sizes and capacitance values available will first be studied. The impedance curves, the parasitic inductance (ESL) and equivalent series resistance (ESR) for each of the technologies will also be outlined. Then the electrical performance under a variety of conditions, such as temperature and DC bias, will be examined.

The function of capacitors in a circuit is often explained with comparison to a water tank.  When a capacitor is compared to a water tank, the battery can be considered as the pump filling the tank with water.

On the circuit, water is similar to dislocation, and the water quantity in the tank can be expressed as the changed quantity pumped in to the capacitor.  Thus, the capacitor’s area corresponds to the dislocated quantity as the tank’s area corresponds to water quantity.

We know that a long and narrow vertical tank can hold just as much water as the short, wide and horizontal tank can. However, the vertical tank has more pressure due to the water than the horizontal one. In the same idea, we can think that for a large capacity, there is a low voltage, and short and wide capacitor, and for a low capacity, there is a high voltage, and long and narrow capacitor.

When the capacitor is connected to the circuit while receiving energy from active components(Battery), one electrode of the capacitor bears a positive electric charge, and the other electrode becomes negative.  The electric charge on the electrode will conduct the opposite charge on the whole.  The electric charge conducted like this is called Permittivity.

The electronics circuits and modules section of this website aims to provide a pot-pourri of electronics design ideas and circuits that can be used within electronics hardware designs. It focuses on providing easy to use designs that can be implemented into electronic product designs, using easy to use formulae and design ideas.

Resistors and capacitors can be considered as the staple components used in electronic circuits. While resistors and capacitors are most commonly used with other active devices, they may also be used on their own in resistor or capacitor circuits, or circuits using combinations of the two.

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.

Zener diodes are manufactured with zener voltages ranging anywhere from a few volts to hundreds of volts. This zener voltage changes slightly with temperature, and like common carbon-composition resistor values, may be anywhere from 5 percent to 10 percent in error from the manufacturer's specifications. However, this stability and accuracy is generally good enough for the zener diode to be used as a voltage regulator device in common power supply circuit in Figure below.

Capacitance is the ability to store electric charge. In its simplest form a capacitor consists of two parallel plates or electrodes that are separated from each other by an insulating dielectric. It is found that when a battery or any other voltage source is connected to the two plates as shown a current flows for a short time as it charges up. It is found that one plate of the capacitor receives an excess of electrons, while the other has too few. In this way the capacitor plate or electrode with the excess of electrons becomes negatively charged, while the capacitor electrode becomes positively charged.

If the battery is removed the capacitor will retain its charge. However if a resistor is placed across the plates, a current will flow in the resistor until the capacitor becomes discharged.