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Capacitor uses - essential tips about where to use the different types of capacitor

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Capacitor Uses and Applications

- a tutorial, overview or summary of the different applications and uses for the different types of capacitor.

Capacitors are used in virtually every area of electronics, and they perform a variety of different tasks. Some capacitors are used for coupling, others for decoupling, while others may be used in filters, and some may be used for power supply smoothing. Again some capacitors will be used in low frequency circuits, and others in high frequency circuits.

There are many different types of capacitor, ranging from ceramic capacitors, to electrolytic capacitors, and silver mica capacitors to various forms of plastic (e.g. polyester) capacitors. Each capacitor type has its own advantages and disadvantages and therefore the uses of the capacitor can be different. Some are better for high frequency uses, whereas others can be used for low frequency applications. Indeed it is necessary to have the right capacitor for the right use of the circuit is to work properly.

Choosing the right capacitor use for the right capacitor is all part of the design process for a circuit. Using the wrong type of capacitor can easily mean that a circuit will not work.

Capacitor types

There are many different types of capacitor that are available today. Each has its own advantages and disadvantages and this means that it is necessary to choose the best capacitor for each use. A list below gives some of the types of capacitor and their advantages and disadvantages.

  • Ceramic capacitor   As the name suggests, ceramic capacitors use ceramic as the dielectric between the plates of the capacitor. These capacitors have a low loss and dependent upon the type of ceramic they use, this will govern their temperature stability. In addition to this ceramic types normally perform well at high frequencies. Values are generally available from a few picofarads up to around 0.1uF.

  • Electrolytic capacitor   This type of capacitor offers a very high level of capacitance per unit volume. They a polar and therefore have to be incorporated into the circuit wit the correct polarity. While they offer a high level of capacitance, the maximum frequencies at which they can operate is limited to around 100 kHz.

  • Plastic film capacitor   There is a variety of types of plastic film capacitor, offering many different properties. Types include polycarbonate, polyester, mylar, polystyrene, and each have their own properties.

  • Silver mica capacitor   These capacitors use mica as the dielectric and have silver plates. They offer a high degree of performance for radio frequencies and in particular they offer a low temperature co-efficient (typically around 50 ppm / C). Although expensive they are ideal for applications such as filters and RF oscillators. However as other ceramic and some plastic film capacitor types have been developed with very good levels of performance, silver mica capacitors are used much less than previously.

  • Tantalum capacitor   This is a form of electrolytic capacitor that uses a tantalum based compound as the dielectric. It has exceedingly high levels of capacitance per unit volume. Like the standard aluminium electrolytic capacitor it is polar, and very sensitive to incorrect polarity voltages or voltages exceeding the maximum rated working voltage.


The Art of Electronics

Paul Horowitz and Winfield Hill

The Art of Electronics





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