Tab Electronics Guide to Understanding Electricity ... - Sciences Club

6 Chapter One
the tube manufacturers would identify their tubes with certain generic
numbers. In other words, a 12AU7 tube would always be labeled 12AU7,
regardless of the manufacturer. Unfortunately, this tradition did not
carry over into the solid-state field. Although there are generic numbers
for solid-state components, they are only used occasionally. Instead, you
must rely on the manufacturer’s cross-references, which are supplied in
their data books. For example, suppose you needed to replace a defective
transistor labeled NTE 130. If you had some NTE 130s in your personal
stock, or if your local electronics shop carried the NTE line of components,
you would simply use another NTE 130 as a replacement. But, if
you didn’t have one and the local parts store only carried the SK line of
components, you would have to cross-reference the NTE 130 to its SK
equivalent. In this case, it would be an SK3027. When you consider that
there are dozens of major parts manufacturers, each using their own
unique part numbers, you begin to appreciate the usefulness of an
exhaustive cross-reference library.
Cross-referencing will also play an important role in acquiring a
respectable parts inventory. All of the large surplus and wholesale electronics
houses offer many electronic components at buy-out or wholesale
prices. In most cases, you will have to cross-reference these parts to
know if you can use them. In addition, if you salvage parts from used
equipment to place in an inventory, you will have to cross-reference the
used parts to know what they are.
One final word on cross-referencing electronic parts—it is not as difficult
as it may seem from just reading this book. On receipt of your
first few data books, spend a few minutes scanning through the crossreference
section. You should easily recognize how the parts are
arranged according to sequential numbers and letters.
Electronics data books also provide the detailed specifications for
electronic parts. When you begin to build or design electronics projects,
you will need a working knowledge of the specifics of the various parts
you intend to use. For example, the device parameters will define the
electrical conditions for reliable operation (breakdown voltage, power
dissipation, maximum current, etc.), and the pictorial diagrams will provide
the necessary mechanical information (case style, lead designation,
pin definitions, etc.).
If you have not understood some of the terms I have used in describing
and explaining data books, don’t worry. When you have a chance to
skim through one, much of what is written here will become clear. The
rest will be understood as you begin to build a few of the projects covered
in the following chapters. The important thing to do right now is