If you are thinking of doing an electronics project, you need to understand basic electronic components and their functions. Some of the components you're likely to encounter are resistors, capacitors, inductors, transistors, motors and diodes. You'll also likely be working with basic buildings blocks such as wires, breadboards on which you can build your projects, and batteries to provide power. If you're just getting started with electronics, look for tutorials online; they usually start with an electronic components list, just as recipes start with a list of ingredients.
Electronic Components and Their Uses
When you open modern electronic devices, you often see integrated circuit chips that look like black boxes mounted onto circuit boards. It's not possible to tell what electronic parts are inside these chips with the naked eye, but they contain miniature versions of many of the same components you can use to build and prototype your own projects.
Fundamentally, electronics revolves around the flow of microscopic particles called electrons through human-made circuits, where their energy is harnessed to do useful things such as generate heat, emit light, move objects or perform computations. Various components exist to control when and where electrons flow or to harness their energy for various tasks.
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Some of the components you'll encounter in electronics include resistors, which hold back the flow of electricity; inductors and capacitors, which store energy; relays and transistors, which are types of electronic switches; and diodes, which only let electricity flow in one direction. You'll also encounter various devices to let an electrical circuit interact with the world around it. These include sensors, which let circuits respond to conditions in the surrounding world; motors, which turn electrical energy into mechanical energy; and light-emitting diodes and lightbulbs, which use electricity to emit light.
Electrical circuits are often drawn with diagrams known as schematics, which use standard symbols and notation to indicate the types of components that should be included. Learning to read schematics is useful if you want to build electronic devices or understand how they work.
What Resistors Do
As the name implies, resistors resist the flow of electricity. They can be used to limit the amount of power going into other components to a level that's safe and doesn't damage the other equipment in a circuit. They typically turn electrical energy into heat energy, so you may notice a resistor heat up as you use it.
The amount of resistance a resistor provides is measured in ohms. When you buy resistors, you specify the resistance you want, and if you need to know the resistance of a resistor in your collection, you can usually find it by looking at colored bands printed on its surface. Memorize what the different colors indicate or look at an online chart.
Most resistors also specify a power rating in watts, which indicates how much electrical power can safely be run through them. Don't exceed that number or you may damage the resistor or even cause a fire.
Some resistors are variable resistors that can be adjusted to provide more or less resistance. The dials on traditional radios usually control variable resistors.
How Capacitors and Inductors Work
Capacitors and inductors are both used for storing energy in an electrical circuit. A capacitor usually consists of two metal plates positioned extremely close to each other but not touching. When an electric current runs through the capacitor, electrons build up on one of the two plates, while the other plate is depleted of electrons. When they're able, the electrons rush to balance themselves between the two plates, and their stored energy is harnessed somewhere in the circuit.
Capacitors can be used to store energy for when a quick burst of power is needed, such as in creating a bright flash in a camera. They can also be used to balance out fluctuations in energy from other sources, such as batteries or wall sockets. Be careful when working with powerful capacitors; if you touch a charged one, you can be shocked if the stored energy passes through your body.
Inductors store energy using a magnetic field. They're usually composed of tiny wires twisted into a coil, a shape that's advantageous for generating such a field. They naturally resist changes in the amount of electrical current flowing through them, which can be used to filter out noise in electrical circuits, such as fluctuating voltages from power or noise in a radio signal.
A capacitor's ability to store energy, or capacitance, is measured in units called farads, while an inductor's ability to do so is known as inductance and measured units called henrys.
Relays, Transistors and Vacuum Tubes
Often you want to use one part of a circuit to control whether electricity can flow through another part of the circuit. For example, you might want to use a heat or light sensor to turn on or off a warning light in certain situations, or you may want to display output on a screen depending on the results of a calculation.
Just as you can turn a light on or off using a mechanical switch, you can also do so using an electrical switch. One of the simplest types of electrical switches is called an electromechanical relay. It uses an electromagnet that generates a magnetic field when current runs through it to open or close a switch. Applying electricity to the magnet opens or closes a path for electricity elsewhere in the circuit.
Transistors serve a similar purpose except rather than work based on electromagnets, they work based on the chemical and physical properties at a microscopic level of the materials used to make them. Transistors can either be used as switches to open or close a circuit based on a voltage applied to a particular place or used as amplifiers, essentially replacing a small application of electrical current with a larger, proportional one.
Transistors are ubiquitous in today's electronics, and they're one of the basic building blocks of modern computing devices. Before they were invented and perfected, devices called vacuum tubes were used instead. Vacuum tubes are much larger, more expensive and less reliable than transistors.
One of the most famous observations about the evolution of contemporary technology is called Moore's Law, named for Intel co-founder Gordon Moore, who observed that about every 18 months, the number of transistors that engineers can fit onto a computer chip of a certain size doubles, while the costs are halved.
Input and Output Devices
Electrical circuits are ultimately only useful for their interactions with the outside world. Electronic devices help us communicate, generate light in the dark, make heat when it's cold, and move things from place to place. We also often want them to respond to changes in their environments without a human needing to turn a dial or flip a switch.
Lightbulbs and light-emitting diodes, or LEDs, are two common components for turning electrical energy into light. Light-emitting diodes are often more efficient than lightbulbs because they give off less waste heat and last longer. You can shop around for lightbulbs and LEDs that give off the amount of light you need in a color you like.
Electrical motors are used to turn electrical energy into mechanical energy. They're common in everything from children's toys to electric cars. Most work by using electromagnets to turn a rotating object.
A wide variety of electronic sensors is also available to alter the flow of electricity in a circuit based on various circumstances. Microphones convert the mechanical energy in sound into electrical energy, light sensors generate electrical energy or allow current to flow when light is present, and other types of sensors influence circuits based on moisture, heat or other environmental factors.