Introduction to electronics and electricity.

1. Getting Started with Electronics
Introduction to Electronics and Electricity
Written by Alvaro Soto-Fernandez
The City University of New York
Architectural Technology Dept.

2. Getting Started with Electronics
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Introduction
Acquiring a basic understanding of electronics and
the fundamentals of electricity is a key component
when working with Physical Computing. While is true
that the Arduino platform makes building circuits from
scratch and programing hardware something very
simple, almost unnoticed. An understanding of how
current, voltage and resistance work will be useful
when expanding the digital toolset at your disposal.
There are many resources, books and online tutorials
to learn about electronics; Charles Platt, Make:
Electronics by O’Reilly is one of the most popular and
simple guides used by many designers and artists.

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The basic Electrical Circuit
The basic electrical circuit Fig.1 will turn and electrical
device ON and OFF. for example, to Light up a small
fan you will need a small battery, Wire and a switch.
If you have a fresh battery and turn the switch On the
LED will light up. This happens because the Electrons
in the battery have a mutual repulsion. Once we open
a pathway for them to scape (by turning the switch
ON), the mutual force of propulsion is what creates an
electrical current.
Fig. 1 -Simple electrical Circuit

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The Water Analogy
In a simple Hydraulic system, shown in Fig. 2 two
factors are key for the function of the system: the
pressure of the water (determined by the power of the
pump) and the amount of water that will flow in the
pipes (this depends of the size of the pipes and the
resistance that the wheel will provide to the stream of
water hitting it.
If you want the wheel to spin faster, you need to
increase the size of the pipe and increase the pressure
that the pump can achieve.
The important parts of the system are: first, the
pressureproducedbythepump,This canbecompared
to the Voltage of the battery, Voltage is measured in
Volts, named after Alessandro Volta. The inventor of
the first battery. Second the resistance that the pipes
and wheel offer to the flow of water is analogous to
Resistance, which is measured in Ohms (after the
German Physicist Georg Ohm). Third the flow of water
is compared current, and is measured in amperes,
after Andre-Marie Ampere, electromagnetism pioneer.
Ohm demonstrated that in a circuit the Voltage, the
Current, and the resistance are all related to each
other.
In simple terms, the more resistance you add to the
flow the less current will travel through the circuit.
From that, the only formulae one really needs to learn
V (Voltage) = R (Resistance) * I (Current)
I = V/R
Fig. 2 -Hydraulic System

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Parallel and Series | batteries
parallel and series connections are useful when using
electronics to control voltage and resistance.
If we want to increase voltage to run an electronic
component e.g LED, motors etc, we would have to
connect our batteries end to end, positive to negative,
in series to double the voltage Fig.3.
If we want to run two electronic components, we could
potentially provide two connections from the battery/
ies, and the force (voltage) will be the same for each
electronic component. However, the battery/ies will
drain twice as fast. But if we wire two batteries side by
side, in parallel Fig. 4, we would get the same voltage
and the batteries will last twice as long.
Fig. 3 -batteries in series Fig. 4 -batteries in parallel

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Parallel and Series | Resistors
Resistors are color coded with stripes allowing you
to identify its resistance value. These values can
be somehow complicated to memorize so there are
several tools you can use, from color charts available
in books like Platt, Make Electronics, to online resistor
color code calculators. But the fastest and easiest
way to determine the value of a resistor is using a
multimeter Fig. 5
Resistors can also be connected in parallel or series
to increase the resistance in a circuit. Resistors in
series are oriented so that one follows the other Fig.6.
Resistors in parallel are oriented side by side Fig 7.
Two equal-valued resistors in series, double the total
resistance because electricity has to pass through
two barriers in succession.
Two equal-valued resistors in parallel, divide the total
resistance by two because electricity has two paths
which it can take, instead of one.
Fig. 5 - Multimeter
Fig. 6 -Resistors in series
Fig. 7 -Resistors in parallel

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Switches
Switches are useful to toggle electricity in a circuit. The
switch shown in Fig. 9 is a Toggle Switch. the center
terminal of this switch is called the pole. Because you
can flip, or throw, this switch to make two possible
connections, it is called a Double-throw switch (SPDT).
Fig. 9 Double Throw Switch