Capacitors Blog

The reliability of a potentiometer depends on its ability to continue performing its intended function. Since the primary function is to provide a continuous and proportional voltage output, the primary reliability considerations are continuity and proportional voltage output. A failure in continuity is always catastrophic, as the device is no longer acting as a potentiometer.

The primary constituents of continuity are:

• Wiper contact to conductive surface
• Continuous conductive surface
• Wiper (output) and excitation terminal continuity

Capacitor is an electromechanical device capable of storing electrical energy (electrons). It differs from a battery, as a battery produces electrical energy as a by-product of chemical activity. A capacitor can function in a circuit like a battery. Or a resistor, or an inductor, for that matter. It can also absorb energy, turning some into heat.

A farad of capacitance is a lot of capacitance. In high voltage, we generally deal in microfarads (mfd.) or picofarads (pf) which are one millionth of a farad and one millionth of 1 millionth of a farad, respectively. Infrequently used, a nanofarad is one thousandth of a microfarad.

Suntan Technology Company Limited
----All Kinds of Capacitors

A super capacitor is also known as a double-layer capacitor. It polarizes an electrolytic solution to store energy electro statically. Though it is an electrochemical device, no chemical reactions are involved in its energy storage mechanism. This mechanism is highly reversible, and allows the ultra capacitor to be charged and discharged hundreds of thousands of times.

A super capacitor can be viewed as two non reactive porous plates, or collectors, suspended within an electrolyte, with a voltage potential applied across the collectors. In an individual super capacitor cell, the applied potential on the positive electrode attracts the negative ions in the electrolyte, while the potential on the negative electrode attracts the positive ions. A dielectric separator between the two electrodes prevents the charge from moving between the two electrodes.

When used in a direct-current or DC circuit, a capacitor blocks the flow of current through it, but when it is connected to an alternating-current or AC circuit, the current appears to pass straight through it with little or no resistance. If a DC voltage is applied to the capacitors conductive plates, a current flows charging up the plates with electrons giving one plate a positive charge and the other plate an equal and opposite negative charge. This flow of electrons to the plates is known as the Charging Current and continues to flow until the voltage across both plates (and hence the capacitor) is equal to the applied voltage VC At this point the capacitor is said to be fully charged with electrons with the strength of this charging current at its maximum when the plates are fully discharged and slowly reduces in value to zero as the plates charge up to a potential difference equal to the applied supply voltage and this is show below.

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We started the development of capacitors with large capacitance and for high ripple current, ahead of other companies. Now, our capacitors for mid- to high-voltage have a high market share.

They have the following common features:

• Through the self-development of high-quality anode foil and electrolyte, high reliability and excellent cost performance have been achieved.
• Our products are used for the equipment that requires a large capacitance such as inverter and large power source.
• Lead-free/Conforming to RoHS Directive.

Suntan Technology Company Limited
----All Kinds of Capacitors

Variable capacitors are mostly used in radio tuning circuits and they are sometimes called 'tuning capacitors'. They have very small capacitance values, typically between 100pF and 500pF (100pF = 0.0001µF). The type illustrated usually has trimmers built in as well as the main variable capacitor.

Many variable capacitors have very short spindles which are not suitable for the standard knobs used for variable resistors and rotary switches. It would be wise to check that a suitable knob is available before ordering a variable capacitor.

Variable capacitors are not normally used in timing circuits because their capacitance is too small to be practical and the range of values available is very limited. Instead timing circuits use a fixed capacitor and a variable resistor if it is necessary to vary the time period.

Suntan Technology Company Limited
----All Kinds of Capacitors

Charging and discharging occurs by the absorption and release reaction of ions in the electric double-layer which is formed between the electrode layer and the electrolyte layer. Gold Capacitors are also called Electric Double Layer Capacitors.

Tantalum electrolytic capacitors exploit the tendency of tantalum to form a protective oxide surface layer, using tantalum powder, pressed into a pellet shape, as one "plate" of the capacitor, the oxide as the dielectric, and an electrolytic solution or conductive solid as the other "plate". Because the dielectric layer can be very thin (thinner than the similar layer in, for instance, an aluminium electrolytic capacitor), a high capacitance can be achieved in a small volume. Because of the size and weight advantages, tantalum capacitors are attractive for portable telephones, personal computers, and automotive electronics.

When sinusiodal or ripple voltage applied to DC Ceramic Disc Capacitors, be sure to maintain the peak-to-peak value or the Peak value of the sum of both AC + DC within the rated voltage.

When start or stop applying the voltage, resonance may generate irregular voltage.

When rectangular or Pulse Wave Voltage is applied to DC Ceramic Disc Capacitors, the self-heating generated by the capacitor is higher than the sinusoidal application with the same frequency. The allowable voltage rating for the rectangular or pulse wave corresponds approximately with the allowable voltage of a sinusoidal wave with the double fundamental frequency.

The allowable voltage varies, depending on the voltage and the waveform.

Silver mica capacitors, also known as silvered mica capacitors, rendered traditional mica capacitors obsolete. Instead of being clamped with foils these use sheets of mica coated on both sides with deposited metal. The assembly is dipped in epoxy. The advantages are:

1.greater stability, since there are no capacitive airgaps that can change dimension

2.airtight enclosure removes the risk of oxidation or corrosion of plates or connections.

3.greater capacitance per volume, since

• there are no airgaps between plates and mica,
• the conducting surfaces can be thinner.
• no clamping mechanism is needed