Passive Components Overview

What are Electronic Passive Components?

Electronic passive components are those in an electrical system or a computer system that do not need to have any electrical power in order to operate. They are not capable of power gain. Some of the different sorts of components include capacitors, fixed resistors, inductors, and surge protection components.

These sorts of components do not amplify or increase the power of the signal. However, it is possible for the passive components to boost voltage or current via an LC circuit that stores electrical energy. In general, there are two type of passive components — dissipative and lossless.

  • Dissipative — these components are not capable of absorbing power from external circuits over time. Most think of resistors when they think of dissipative passive components.
  • Lossless — these components do not have a net power flow into or out of the component. Some of the common examples include oscillators, transformers, capacitors, and inductors.

Most of the components, often called a two-port parameter, have two terminals linked via an electronic network. Some good examples of this would be electronic filters and transistors. Other passive components use circuit architecture. Examples would be capacitors and transformers.


How Are Passive Components Different from other Non-Passive Components?

All types of electrical components will fall into one of two categories — active or passive. Understanding the difference between these two categories is one of the keys to understanding how most electronic devices work.

The biggest difference between passive and non-passive, or active, components is whether they need an external source of power for their operation or not. The passive components do not, while the active components do. Components and devices that produce energy, as current or voltage, are active. Passive components will store or maintain energy instead. Another one of the key differences between the two is that active devices have the ability to control the energy flow, or current, in a circuit. Passive components are not able to do this in most cases, although they can limit the flow of current.


What is the Concept of Passive Components?


The basic concept behind passive components is that they drop energy rather than generate energy, as active components do. They can work without the application of power, and many are actually able to perform different sorts of functions. They have been useful for many different types of electronic devices in the past, and they are still a major part of electronics today.


What Are Passive Components Used For?

Passive components are in resistors, capacitors, inductors, connectors, and more today. The resistors are actually one of the simplest types of electronic components. As the name would suggest, they resist flow of current within a circuit. All types of electronic devices, and even cables, have some sort of resistance in them, and the resistor will determine just how much of a voltage drop it has. Capacitors are different and have a different use. They can smooth DC circuits, store power, offer signal coupling, decoupling, noise filtering, and tuned circuits.


Which Modern Devices Require Passive Components to Function?

Many different sorts of devices need to have passive components in order to function properly. The resistor, which is one of the most basic forms of passive component, is necessary for fuses, sensors, and heaters, as well as many types of lights. You will also find these in a host of other modern electronics items that you have around the house, including computers, microwaves, game consoles, digital cameras, MP3 players, cell phones, and televisions. Thermostats and rheostats utilize passive components, in the form of variable resistors, as well.


What Kind of Applications Need Passive Components to Function?

A host of different types of applications relies on passive components to function properly. One of these is filter applications. They use both resistors and capacitors, and it is possible to create designs that provide just the right frequencies and performance needed. Some of the filters include high pass filters, low pass filters, band pass filters, band stop filters, all pass filters, notch filters, and equalization filters.

Passive components are important for digital electronics and helping to keep them stable. They protect the microchips in these devices and ensure that they are not receiving too much noise from the power signal. Without the passive components, it would have the potential to cause strange and unpredictable behavior with the devices.

Capacitive sensing applications are starting to become more and more common in different types of devices, including consumer electronics. Capacitors are helpful in this field, and they are a major part of making sure the application is working properly. These sensing applications will measure things such as acceleration, fluid level, position, and humidity. They could also measure changes in the capacitor as well. Often, capacitors will be in devices that need to have the AC pass while blocking the DC current.


History of Passive Components

Since the dawn of the electronic device — of nearly any type — there has been a need for what passive components can offer. In the 1930s, the development of passive microwave components was getting underway, and as circuits started to evolve in the decades that followed, the need for newer and better passive components such as capacitors and resistors started to grow. They evolved with it, and many of the ones in use today are a fraction of the size of their counterparts from yesteryear. However, they are of a much better quality and can do the job far better.

As the electronics field continues to change and evolve, capacitors, resistors, inductors, and all other types of passive components will likely grow and change along with it. These changes promise to make electronics of all types more efficient and more reliable.


What Types of Passive Components Exist?

Passive components run the gamut when it comes to their form and function in different devices, and there are many types out there. The following is a list of some of the most common types of passive components found today, and information on what each of them does.

  • Capacitors — a capacitor is a component that can actually gather and hold a charge in a way that is similar to what a battery does. It can hold the charge even when the voltage is no longer applied. Many different sorts of capacitors exist including film capacitors, mica capacitors, ceramic capacitors, electrolytic capacitors, aluminum electrolytic capacitors and tantalum electrolytic capacitors. They use capacitors for energy storage, pulse weapons, power conditioning, suppression and coupling, motor starters, signal processing, and more. A large number of different types of electronics use capacitors today.
  • Ferrite Cores — the cores made from ferrite, a ceramic compound that includes a mix of iron and another type of metal. Ferrite is common in many types of electrical components, including antennas. This magnetic core features wound components, such as windings from a transformer and inductors. It is useful because it offers low electrical conductivity along with high magnetic permeability. The most common uses for ferrite cores are for signal transformers and power transformers. They are useful for many different sorts of electronics devices large and small. The signal transformers using the cores are generally small and have higher frequencies. The power transformers are larger and they have lower frequencies. The cores come in different shapes as well, called shell, cylindrical, and toroidal.
  • Fixed Resistors — a fixed resistor is a part of an electrical circuit. The resistor helps to reduce the flow of current through the circuit. Resistors come in two different types, fixed and variable. The fixed resistors have a specific and predetermined value and are unable to change. When people choose fixed resistors, they need to consider the value, as well as the tolerance and the upper power rating to make sure it will work properly with the device. Tolerance will let them know the performance boundaries, while the power rating will show the upper power limit the resistor can handle. Two different types of fixed resistor exist — metal film and carbon. Carbon resistors are good for general usage and are generally cheaper. The metal film resistors are high quality and are best when the device needs a higher tolerance.
  • Inductors — these passive components will store energy within their magnetic field and then provide the circuit with that energy when it needs it. They have a cylindrical core that has a number of coils of conducting wire around it. These are different from capacitors, since they store energy in an electric field and inductors store their energy in a magnetic field. Inductors attempt to maintain a constant current.
  • Passive Filters — the passive filters are helpful for providing circuits with the right frequency characteristics to work properly. Some of the common examples of these sorts of filters include low pass filters, which remove higher frequencies in circuits and high pass filters, which filter, or remove the lower frequencies. They are often used in amplifiers. Other types include band pass filters, band stop filters, ceramic filters, and TV SAW filters.
  • Rotary Encoders — another term for rotary encoders is shaft encoders. These devices change or convert the motion or position of an axle or shaft to an analog or digital code. The two main types of rotary encoders are incremental and absolute. They are useful in many different fields, including robotics, computer input devices, robotics, rotating radar platforms, and industrial controls.
  • Sounder — a sounder, sometimes called an electric bell, utilizes electromagnets and electrical current to work. They are actually quite similar to buzzers.
  • Buzzer — a buzzer is a device used for audio signaling. The buzzers use useful for alarms, timers, and similar items. They can even confirm keystrokes on a keyboard and clicks on a mouse. The devices could be mechanical, electromechanical, or piezoelectric. They often work in conjunction with passive components in electronic devices and systems.
  • Microphone Components — the components that make up a microphone circuit work together to create an acoustic to electric sound. They use transducers and sensors that can convert the sound that it picks up into an electrical signal. Microphones that utilize this simple setup are in many different sorts of common devices today, not simply microphones one sees on stage. Some of the other types of applications include phones, hearing aids, radios, VoIP, and much more.
  • Surge Protection Componentssurge protectors are a part of nearly every home and office today. They provide your expensive electronic devices with a bit of added protection so they do not receive a surge of electricity, which would ultimately destroy them. The main components in the surge protector can include the MOV, or metal oxide varistor, transient voltage suppression diode, thyristor surge protection device, gas discharge tube, selenium voltage suppressor, carbon block spark gap overvoltage suppressor, quarter-wave coaxial surge arrestor, and series mode surge suppressors. Having surge protection of sufficient quality for all of the electronic devices in the home is always a good idea.
  • Variable Resistor — the variable resistor is different from the fixed resistor in that it lets the user have more control over the amount of resistance in the circuit. When the resistance increases, the current decreases and vice versa. The variable resistors have two components. The element is the material that provides the resistance, and it is on one of two track types, either logarithmic or linear. The other component of the resistors is the movable component, and this allows one to set the resistance. Usually, this is a knob or a slider of some type. One of the most common examples of a variable resistor would be a potentiometer.

The preceding are some of the most common types of passive components. They find their way into so many of the different devices people use on a daily basis that you are likely using them all the time without ever really seeing them or understanding just how important they really are.