COMPONENTS - ACTIVE
When a beginner to electronics first looks
at a circuit board full of components he/she is often
overwhelmed by the
diversity of do-dads. In these next few sections we
will help you
to identify some of the simple components and their
Then you should be able to call them resistors and
of "Whatchamacallits". In later sections we will go into the
each component. Just try to familiarize yourself with
Electronic component are classed into either being
or Active devices.
Active Devices are components that are capable of
or currents and can create a switching action in the
circuit. In other
words, "Devices with smarts!" Examples are Diodes,
Transistors and Integrated
NOTE: Most Active components are semiconductors. More on
this in later
A Passive Device is one that contributes
no power gain (amplification) to a circuit or system. It
has not control
action and does not require any input other than a signal
to perform its
function. In other words, "A components with no brains!"
Examples are Resistors, Capacitors and
Diodes are basically a one-way valve for electrical
current. They let
it flow in one direction (from positive to negative)
and not in the other
direction. Most diodes are similar in
appearance to a resistor and
will have a painted line on one end showing the
direction or flow (white
side is negative). If the negative side is on the
negative end of the circuit,
current will flow. If the negative is on the
positive side of the circuit
no current will flow. More on diodes in later
Light Emitting Diodes:
LEDs are simply diodes that emit light of
one form or another.
They are used as indicator devices. Example: LED lit
equals machine on.
They come in several sizes and colors. Some even
emit Infrared Light which
cannot be seen by the human eye.
The transistor is possibly the most important
invention of this decade.
I performs two basic functions. 1) It acts as a
switch turning current
on and off. 2) It acts as a amplifier. This makes an
output signal that
is a magnified version of the input signal. More on
transistors in later
Transistors come in several sizes
depending on their application.
It can be a big power transistor such as is used in
power amplifiers in
your stereo, down to a surface mount (SMT) and even
down to .5 microns
wide, such as in a microprocessor or Integrated
Integrated Circuits, or ICs, are complex circuits
inside one simple
package. Silicon and metals are used to simulate
transistors, etc. It is a space saving miracle.
These components come in
a wide variety of packages and sizes. You can tell
them by their "monolithic
shape" that has a ton of "pins" coming out of them.
are as varied as their packages. It can be a simple
timer, to a complex
logic circuit, or even a microcontroller
(microprocessor with a few added
functions) with erasable memory built inside.
Microprocessors and other large scale ICs are very
complex ICs. At
their core is the transistor which provides the
logic for computers, cars,
TVs and just about everything else electronic.
Packages are becoming smaller
and smaller as companies are learning new tricks to
make the transistors