Learning Home Electronics – Building Circuits on Your Own – Part 1

Electrical circuits basics

Designing and building electrical circuits is a fascinating hobby. Before building any electrical circuit we must learn the language called “electronics”. Like any other language, there are some basic rules that we must know and understand. These rules will help us reading and designing simple and complicated electronic circuits. This book’s main target is to teach the electronics language to readers that are not familiar with electronics by using group of rules and simple equations that describe the behavior of every electronic component and the relationship between the components in the circuit.

Basic electronic circuit can be separated to three sections: Power supply, wires, load.

Power supply (battery, wall mounted transformer etc.) drives current through the wires to the load (Lamp, Phone, motor, TV, etc.). If you would like to design electrical circuit to light a lamp or powering alarm or driving a motor with commands from a computer, you must understand the behavior of the components in the design according to their datasheets that are available from the component’s manufacturers. Understanding each component behavior will help you set the appropriate conditions to each of the components on your design. Your goal as a circuit designer is to know how to choose the best components to make your design work.

There are some basic electronic components that can be found in almost every electronic design. In the first article we will learn what are these basic components and their behavior in the electronic circuit, but first we must learn some basic terms and definitions.

Numbers Scientific notation

Scientific notation is a method for writing very small or very large numbers is a short way. For example: K [Kilo] = 1000, m [mili] = 1/1000.

Large and small numbers are very common in electronics


1. 0.003 ampere current = 3mA (3 mili ampere) or 3*10-3

2. capacitor with size of 0.0000000007 Farad = 7nF (7 Nano Farad) or 7*10-9

3. frequency with size of 20,000,000,000 Herz = 20GHz (20 Giga Herz) or 20*109

Electric wire (conductor)

Electric wire is called a conductor because it is made of a conductive material that can flow current. There are many types of conductors with many parameters and shapes, but don’t worry, there are only several common conductors that can be used in an electronic circuit according to the signals that are active in the design. We will soon find out what type of conductor can be used for each of our electronic designs. The conducting wire is like a pipe that helps the current flow from one point to another in the circuit. The conducting wire is usually covered with isolating material (usually plastic/nylon) that prevents the conductor to be shorted with other conductors on the electronic circuit. Many circuits are made of a printed card where the conductors are printed and are part of the card (some of them are hidden in internal layers of the card).

Electric current

Electric current is defined as a flow of electrons through a conductor (similar to water flow inside a pipe). Electric current is defined by size and direction. We can calculate the size of electric current in every conductor in the circuit according to the components and connections between them.

Size of electric current in a conductor

Electric current has the symbol “I” and measured with “ampere” units. The size of the electric current is relative to amount of electric charges flowing inside the conductor during time. We will see soon how to calculate the size of electric current in the electronic circuit.

Direction of electric current

In addition to the electric current size there is also a direction to the current flow inside the conductor. Direction of current inside a conductor is the opposite direction of the electric charges flow.

This is the first article of series of article on – learning home electronics hobby.

Source by John Derek

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