DC - AC Circuits

973 Pages·2004·8.11 MB·English

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Introduction to Electricity and Electronics
The field of electricity and electronics is exciting and rewarding, and it
has a major impact on the lives of nearly every person in the world.
This chapter will highlight a few applications of electronics and
describe several of the endless career opportunities in electronics. You
will learn about the composition of matter, including particles that are
so small they cannot be seen—even with a microscope. This chapter
will also introduce you to many of the units used to measure electrical
quantities. Since the measurement of electrical quantities requires the
use of both very small and very large numbers, you will also learn some
new methods for manipulating and expressing numbers.
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1.1 Electronics in Today’s World
It is not practical to list all the applications of electronics devices and circuits. First, the list
KEY POINTS would be unbelievably long. Second, new applications are being added so quickly, you
could never reach the end of the list. The following section illustrates the wide range of
Nearly every person in
the civilized world is existing applications by describing a few of the major fields that utilize electronics.
directly affected by elec-
tronics on a daily basis.
Applications
COMPUTERS
All forms of modern computers are electronic devices. Computers are used to control such
diverse systems as airplane navigation and flight, business record keeping, automotive
emissions monitoring, elevator operation and scheduling, satellite communications, and
environmental control. Figure 1-1 shows a computer system being used to simplify the
measurement and display of complex electronic measurements.
COMMUNICATIONS
Communications takes a wide range of forms, including telephone systems, fiber-optic
links, microwave transmissions, private and commercial radio networks, cellular phone
systems, television, satellite links, and underwater communications for submarines.
AGRICULTURE
Electronics is used for many agricultural applications, including livestock monitoring and
feeding, automatic equipment controls, livestock environmental control, tractor engine
control, and dairy production control and monitoring.
Figure 1-1. Electronic computers are used in many fields.
(Courtesy of National Instruments)
Introduction to Electricity and Electronics 33
CONSUMER ELECTRONICS
Consumer electronics includes such common items as televisions, video cassette recorders
(VCRs), radios, stereo systems, laser disk players, home security systems, and many elec-
tronic convenience items.
AUTOMOTIVE ELECTRONICS
This area includes automotive sound systems, emissions control, engine control, radar
sensors, two-way radios, mobile telephones, garage door openers, and complete onboard
monitoring systems.
MARINE ELECTRONICS
Marine electronics includes sonar equipment, navigational systems, communications
equipment, emergency beacons, marine telephones, and many engine control and moni-
toring devices.
AEROSPACE APPLICATIONS
There are incredible numbers of electronic systems aboard commercial and military
aircraft. These include systems for navigation, weapons control, communications, auto-
pilot, automatic electronic identification, environmental control, and electronic counter-
measures for interfering with enemy electronics. Of course, aerospace applications extend
to include the various forms of spacecraft and satellites, which have an extensive array of
electronic systems. Figure 1-2 shows a spacecraft application of aerospace electronics.
INDUSTRIAL ELECTRONICS/ELECTRICITY
Industrial electronics is a broad classification that includes such things as automated
factory equipment, computerized monitoring and control for chemical processes, auto-
mated warehouses, and many forms of process control systems for monitoring and
controlling manufacturing processes.
ROBOTICS
Robots are essentially a subset of industrial electronics. They are computer-controlled
machines that can perform repetitive tasks with exceptional precision, Figure 1-3 (See
page 5). Some robots are mobile and resemble a vehicle. Others consist of a mechanical
arm and hand that can be positioned very accurately.
SPORTS
There are numerous electronics applications in sports such as timers, scoreboards, elec-
tronic training equipment, speed-measuring equipment, communications systems, and
video equipment.
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Figure 1-2. A satellite tethered to the space shuttle to gather
data on a variety of plasma physics and electrodynamics
experiments. (Courtesy of NASA)
MEDICAL ELECTRONICS
Many medical procedures rely on sophisticated electronics devices. A few of these include
x-ray machines, laser surgery, ultrasound imaging, magnetic resonance imaging (MRI), heart-
pacing equipment, artificial kidneys, electrocardiograms, and many other diagnostic tools.
CAD/CAM
Computer-aided design (CAD) and computer-aided manufacturing (CAM), collectively
called CAD/CAM, describe an integrated manufacturing environment where all phases of
a product’s development are done with the aid of a computer. Once a designer has final-
ized the design of a new product with an engineering computer, the engineering computer
then communicates directly with other computers to order and distribute materials, and
to actually build the new product.
Although the preceding applications only begin to scratch the surface of all existing appli-
cations for electronics devices, they do illustrate the extreme range of electronics applica-
tions. An interesting experiment is to try to name fields that have absolutely no
relationship with electronics. It’s very hard to do. For example, fields such as fishing, hog
Introduction to Electricity and Electronics 55
Figure 1-3. A modern industrial robot. (Courtesy of Stäubli)
KEY POINTS
raising, model building, spelunking, and scuba diving, which seem to be unrelated to elec-
There are tremendous
tronics, all benefit from applied electronics.
career opportunities for
electronics technicians.
All of the positions
Career Opportunities
require a thorough
understanding of basic
Because there is such an endless list of electronics applications, there is a similar list of
electronics and a knowl-
possible career opportunities in the field of electronics. The following career positions were
edge of the characteris-
selected to show the range of opportunities. The job titles are generic. Many companies
tics of electronic
refer to similar positions by different job titles. components.
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BENCH TECHNICIAN
A bench technician troubleshoots and repairs defective electronic equipment that has been
brought to the shop, Figure 1-4. The equipment may be any type of electronic device.
Some examples are consumer products, computers, telephones, and medical devices.
FIELD SERVICE TECHNICIAN
The field service technician goes to the customer’s site to perform equipment calibration,
troubleshooting, and repair. Some equipment that is serviced in this manner includes
computers, radar installations, security systems, environmental control systems, and
point-of-sale (POS) terminals.
INDUSTRIAL TECHNICIAN/ELECTRICIAN
This technician performs the tasks of both bench and field service technicians, but is
generally limited to a single site. For example, an industrial technician working for a
chemical company would install, calibrate, and repair many types of industrial electronics
equipment within her employer’s facility—both in the plant and in the repair shop.
ENGINEERING TECHNICIAN
An engineering technician—also called a research and development (R&D) technician—
generally works in a laboratory environment. He builds prototype systems, installs and
Figure 1-4. Bench tech at work. (Courtesy of National Instruments)
Introduction to Electricity and Electronics 77
tests modifications to existing equipment, and plays a key role in the development cycle
for new products. This technician often serves as a coordinator between the engineering
and manufacturing departments during the early production phase of a product.
APPLICATIONS ENGINEER
Many technicians become applications engineers once they have become experts on their
employer’s products. An applications engineer meets with customers, analyzes their appli-
cations, and shows the customer how to effectively utilize the products sold by her
company. This position requires strong technical skills and well-developed interpersonal
skills.
TECHNICAL WRITER
Most companies produce documentation to accompany their products. Some of the docu- KEY POINTS
mentation is proprietary and is used only within the company. Other documentation,
In addition to technical
such as the operator’s manual, is delivered to the customer. A technical writer develops this
skills, the successful tech-
documentation. nician also needs to
develop interpersonal
If you want to succeed in career positions similar to those cited here, then you will want
skills and communication
to master the concepts and techniques presented in this text. This text is about basic skills.
electronics. An understanding of basic electronics is essential for success in any branch
of electronics.
Important Milestones
This section is included to provide you with a brief historical perspective. Figure 1-5
shows a time line extending from the seventeenth century with several key milestones
along the way. Each milestone marker lists a major invention or discovery that helped
shape the field of electronics. The time line represents over 330 years of electronics
developments.
It is particularly interesting to note that the rate of significant discoveries is KEY POINTS
continuing to increase. For example, the first nine discoveries listed in Figure 1-5
The development of new
account for 241 years of the time line. The next six developments occurred over a
devices and new technol-
52-year period. The last three milestones shown in Figure 1-5 cover only 18 years. A ogies is continuing at an
complete chart of all significant discoveries in electronics would be enormous, but it incredible, and increas-
would provide even more evidence of the tremendous increase in the rate of important ingly rapid, rate.
discoveries.
Electronic Components
As you study the material in this and subsequent texts, you will learn the electrical charac-
teristics of many electrical and electronic components. This section is meant to introduce
you to the physical appearance of some of the components you will be studying. Similar
devices can often have dramatically different appearances. As a technician, you must learn
to recognize a component from its physical appearance. You will learn the operation of
some of these components later in this text.
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1832
1660
1821
Generator
Static electricity
machine
1796 Motor
1844
Battery
Long distance
1876 telegraph
Telephone
1883
1896
Edison effect
Radio
transmission
1911
Super-
conductivity
1901 1906
Transatlantic Vacuum tube
radio amplifiers
1939
Electronic
television
1947
1946
Transistor
Universal
computer
1958 1975
Integrated Personal
circuits 1960 computer
Ruby
laser 1987
Ceramic
superconductors
1993
Hand-held
satellite receivers
Figure 1-5. Today’s electronics is a result of many historic discoveries.
Introduction to Electricity and Electronics 99
RESISTORS
Resistors are used to limit the amount of current flow in an electrical circuit. Resistors vary
in size from less than 0.04 inch to well over 12 inches in length. They are generally
coded—either with numbers or colored bands—to indicate their value. Figure 1-6 shows
examples of several resistor types.
(a) (b)
Figure 1-6. (a) Resistors vary in value and physical appearance. Their value is indicated with a printed
number or with color-coded bands. (b) The schematic symbol for a resistor.
CELLS AND BATTERIES
You are already familiar with several types of cells and batteries that are used as sources of
voltage: flashlight battery (D cell), 9-volt transistor radio battery, AAA cell, 12-volt car
battery, watch battery, and so on. Figure 1-7 shows several typical cells and batteries. Some
batteries are small enough to fit inside a watch or hearing aid. Others have a volume of
several cubic feet and weigh hundreds of pounds.
(a) (b) (c)
Figure 1-7. (a) Batteries vary in voltage, current capacity, chargeability, and physical
appearance. (Courtesy of Duracell) (b) Schematic symbol for a cell. (c) Schematic
symbol for a battery.