Hardware Reference
In-Depth Information
Electronic Basics
You are delving into a new world of electronics by using the Raspberry Pi's GPIO pins.
If you have never created any electronic circuits before, following the tutorials in this
adventure will be a good place to learn basic electronics. To get started, you should
become familiar with the electronic concepts and components in the following list.
•
Current
is the rate at which electrical energy lows past a point in a circuit. It is
the electrical equivalent of the low rate of water in pipes. Current is measured in
amperes (A). Smaller currents are measured in milliamperes (mA).
•
Voltage
is the diference in electrical energy between two points in a circuit. It is
the electrical equivalent of water pressure in pipes, and it is this pressure that
causes a current to low through a circuit. Voltage is measured in volts (V).
•
Resistors
are electrical components that resist current in a circuit. For example,
LEDs can be damaged by too much current, but if you add the correct value
resistor in series with the LED in the circuit to limit the amount of current, the
LED will be protected. Resistance is measured in
ohms
. You need to pick a resis-
tor with the correct value to limit the current through a circuit; the value of a
resistor is shown by coloured bands that are read from left to right. he exercises
in this adventure will use some resistors and explain how to read the value.
•
A
diode
is a device that lets current low in only one direction. A diode has
two terminals, called
anode
and
cathode
. Current will low through the diode only
when positive voltage is applied to the anode, and negative voltage to the
cathode.
•
A
light-emitting diode
or
LED
is a diode that lights up when electricity passes
through it. An LED is an example of an output device. LEDs allow current to
pass in only one direction. hey come in a variety of colours, and have one short
leg and one long leg, which helps you to determine which way round they need
to be placed in a circuit for current to low through them. he exercises in this
adventure will use some LEDs.
•
A
capacitor
is used to store an electric charge. he capacity that this component
has is measured in farads (F). A farad is a very large quantity, so most of the
capacitors you see will be measured in microfarads.
•
A
breadboard
is a reusable device that allows you to create circuits without need-
ing to solder all the components. Breadboards have a number of holes into which
you can push wires or jumper cables and components to create circuits. he two
columns of holes on either side of the breadboard, between red and blue lines, are
for power. he column next to the red line is for positive connections and the
column next to the blue line is for negative connections (see Figure 8-4 for an
example of a breadboard). he exercises in this adventure use a breadboard.
•
Jumper cables
can be used to connect the GPIO pins on the Raspberry Pi to
a breadboard or other components. hey are reusable and do not require
