Getting Started with ElectronicsIntroduction to Electronics and Electricity Written by Alvaro Soto-Fernandez

The City University of New YorkArchitectural Technology Dept.

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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 pressure produced by the pump, This can be compared 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