Hardware Hacking Projects for Geeks

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Part II: Advanced Hacks, Tools, and Techniques

Prefixes are often added to the capacitance value, so that you can avoid

writing out large numbers. Table II-2 gives the common prefixes and their

value multiplier.

Table II-2. Capacitance value prefixes

Prefix Symbol Value multiplier

Pico p 10E-12

Nano n 10E-9

Micro

µ

10E-6

Milli m 10E-3

Kilo K 10E3

Mega M 10E6

Giga G 10E9

For example, if a capacitor has a value of 10 pico-Farads (10 pF), it has a

value of 10 x 10E-12 Farads (10E-12 is scientific notation for 1 divided by

10 to the 12th power).

Types of capacitors

There are a large number of capacitor types. Each type has different char-

acteristics and is used for different applications. A few of the more common

types are listed here with their general characteristics.

Electrolytic

The electrolytic capacitor is most like a regular battery. It contains layers

of metal foil surrounded by an electrolyte paste (thus the name “electro-

lytic”).

These capacitors are generally used for low-frequency filtering such as with

power supplies and audio circuits. They can have values from a few tenths

of a micro-Farad to over one Farad. The value tolerance of electrolytic

capacitors is typically large; plus or minus 20 percent is not uncommon.

The values of these capacitors vary greatly with temperature. When a high-

frequency signal is applied to this type of capacitor ...