COMPONENTS - PASSIVE
When a beginner to electronics first looks at a circuit
board full of
components he/she is often overwhelmed by the diversity of
these next few sections we will help you to identify
some of the
simple components and their schematical symbol. Then you
should be able
to call them resistors and transistors instead of
later sections we will go into the workings of each
try to familiarize yourself with the basics for now.
Electronic component are classed into either being
devices or Active devices.
A Passive Device is one that contributes no power gain
to a circuit or system. It has not control action and does
any input other than a signal to perform its function. In
"A components with no brains!" Examples are Resistors,
Active Devices are components that are capable
of controlling voltages or currents and can create a
switching action in
the circuit. In other words, "Devices with smarts!"
Examples are Diodes,
Transistors and Integrated circuits.
This is the most common component in electronics. It
is used mainly
to control current and voltage within the circuit.
You can identify a simple
resistor by its simple cigar shape with a wire lead
coming out of each
end. It uses a system of color coded bands
to identify the value of the component (measured in
Ohms) *A surface mount
resistor is in fact mere millimeters in size but
performs the same function
as its bigger brother, the simple resistor. A
potentiometer is a variable
resistor. It lets you vary the resistance with a
dial or sliding control
in order to alter current or voltage on the fly.
This is opposed to the
"fixed" simple resistors.
Capacitors, or "caps", vary in size and shape - from
a small surface
mount model up to a huge electric motor cap the size
of a paint can. Whatever
the size or shape, the purpose is the same - It
storage electrical energy
in the form of electrostatic charge. We will get
into the mechanics and
further properties of this later. The size of a
capacitor generally determines
how much charge it can store. A small surface mount
or ceramic cap will
only hold a minuscule charge. A cylindrical
electrolytic cap will store
a much larger charge. Some of the large electrolytic
caps can store enough
charge to kill a person. Another type, called
Tantalum Capacitors, store
a larger charge in a smaller package.
You may remember from science class that adding
to a coil of wire produces a magnetic field around
itself. This is how
the inductor works. It is charged with a magnetic
field and when that field
collapses it produces current in the opposite
direction. Inductors are
used in Alternating Current circuits to oppose
changes in the existing
current. The mechanics of this will be described
later. Most inductors
can be identified by the "coil" appearance. Others
actually look like a
resistor but are usually green in color.
A. Air Core, B. Iron Core, C. Powered Metal Core.