Active VS passive components
If you look at any assembled circuit board, you’ll see many things on its surface. These are the components – the bread and butter of electronics. Each one has a different role, but the common ones make up around 80% of the projects you’ll be working on.
What are components?
Basic devices that affect electrons and their associated fields are called electronic components. They make an electronic circuit function. Components have several electrical terminals (leads) used for connecting to other components or creating an electronic circuit. The circuit is usually created by soldering the components to a PCB (printed circuit board) . It will direct and control the electric current to do various functions.
Before you start building electrical projects, you have to understand some common electrical components and how they interact with one another. After all, you wouldn’t build a house without understanding how the materials worked together beforehand. The first thing to know is that components can be either active or passive. In this tutorial, we’re going over the most common components.
Active components can inject power into a circuit, electrically control or amplify the current. Generally speaking, they have “an active role” in the circuit. They manipulate the flow of electricity in some way.
Diodes allow the current to go in only one direction. They have a very high resistance for currents going in another direction, blocking it in the process. They essentially convert the alternating current into the direct current. Diodes come in many shapes and sizes, while the light-emitting diodes, or LEDs , are among the most popular.
Transistors are three-terminal semiconductor devices. They are used to amplify electrical signals and switch devices. There are two types of transistors used in electronic circuits – bipolar junction transistor (BJT) and field-effect transistor (FET).
Integrated circuits (ICs) are multiple components combined into one. There is a wide variety of integrated circuits and it would be impossible to go over what each of them does. They range from the very simple ones to the very complex ones with over a billion circuit elements. You’ll want to reference the IC’s datasheet when working with them because of this. They are so widely used that you can find an integrated circuit in virtually every electronic device today.
Passive components, as the name suggests, are the opposite of the active components. They won’t control or amplify the current or do anything of the sort. They can only attune the electrical signal. You can think of them as components that consume and store energy.
Resistors are used to limit the flow of the current. This is of utmost importance. If they weren’t used, the components would take in too much of the current and burn up. This opposing force is called the resistance and is measured in ohms (Ω).
Capacitors are components that can store electrical energy in an electrical field. This is called charging. When capacitors are releasing the energy, it is called discharging. It is measured in farads (F). They allow alternating current to flow through, but not direct current.
Similar to capacitors, the inductors store electrical energy. They produce the so-called inductance, a tendency of a conductor to oppose the change in the electric current flowing through. The unit of inductance is henry (H). Unlike capacitors, they store energy in a magnetic field. They allow direct current to flow through, but not alternating current.
Transformers are components with no moving parts that transfer electrical energy from one electrical circuit to one or more others. This is done with a changing magnetic field.
Switches are simple electronic components that can connect or disconnect the conducting path in a circuit. A switch can operate manually or as a sensing element. The most common switch is the light switch, the one used to turn on the light in a room.
The importance of having both types of components
Just because passive components can’t give energy continuously to the circuit, that doesn’t mean they shouldn’t be used. Quite the opposite. Imagine if you didn’t use resistors in your projects. The current would be too strong and you could damage the components in the circuit. Now add the right resistor and your circuit functions well and no component gets damaged.
Another great example is having inductors or capacitors in a project. If there are none, the energy supplied by the active device will not be stored anywhere. It will flow continuously until the device is switched off. This is bad if we want to use the stored energy when the voltage source is inactive. When the device is turned off, the capacitor will start discharging, providing energy to the circuit.
Without passive components, active components wouldn’t be able to accomplish their tasks. Similarly, without active components, passive components wouldn’t have much use. Think of it like building a house. You need bricks and other materials, just like you need passive components. With electricity, heating, and plumbing, you’re adding functionality to that house, or active components.
If you’re having trouble recognizing whether the component is active or passive, don’t worry. It’s really simple to figure it out. The main difference is that active components require a power source to perform their tasks. Transistors need the power so they can amplify it, but switches can’t change their states without it.
The best way to learn about how the components work together is by building projects. Check our tutorials page to find something fun to make and learn more about active and passive components.
Products used in this tutorial
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