Basic concepts

Active and Passive Components | Basic Electronics

Hello guys. In my today’s article, I am going to cover a basic but most essential topic, that is necessary to understand. The topic covers an explanation about active and passive components and a basic understanding of various active and passive components. So let’s start with the topic ” active and passive components”.

What are the active components?

Active components are those which are capable to amplify or modify the signal or produce gains in amplitude or power. These are the components able to modify the electrical signal. There are different active components used according to their requirement.

These components provide devices the ability to alter the signal. These components can perform an independent operation.

Types of Active components

  • Transistor:- Transistors are a three-terminal semiconductor device made by sandwiching either N-type between a pair of two Ptype or a P-type between a pair of two N-type materials. It is an electronic component that works as a switch between various electrical stages or can be used for amplification or regulation of current or voltage signals. Transistors play a crucial role in the field of electronics. Basically, transistors are classified as BJT (Bipolar Junction Transistor) and FET(Fied Effect Transistor) or MOSFET(Metal Oxide Field Effect Transistor). Based on the material type, they are of two types:-

NPN:- Transistors made by sandwiching a P-type material between two N-type channels.

PNP:- Transistors having N-type material sandwiched between P-type.

active and passive components
  • Diode:- Diodes are a two junction component made by sandwiching 2 PN or NP together. The main job of a diode is rectification, i.e converting AC to DC. There are also other important uses of a diode such as Flyback protection and current and voltage regulation. Different types of diodes for the different purpose shown in below image:-
active and passive components
  • SCR:- Silicon Controlled Rectifier. SCRs are semiconductor devices with 4 layer material, i.e p-n-p-n junctions. SCRs are used for controlling current and power in thyristor circuits. It is basically a Schottky diode with one extra terminal called gate.
active and passive components
  • MOSFETs:- MOSFETs are Metal Oxide Field-Effect Transistors. They are also transistors but used for high-speed switching and powerful conditions. They play a crucial part in the field of power electronics. Current regulation, Voltage regulation, high-speed switching, power amplification.
  • ICs:- Integrated Circuits. ICs are Integrated Circuits, in these, there are several components and circuitries integrated. They are capable of performing several operations independently with just addition with some small passive components. It can visibly reduce the circuitry size. Some examples of ICs are IC555, CD4017, CD4047,etc.

What are Passive Components?

Passive components are those components that do not modify, change or produce electrical signals. Instead, they store energy in the form of voltage and current. There are different passive components:-

  • Inductor:- Inductor is a passive component that is a coil of wire wounded across a piece of a core. It is basically consisting of insulated wire and a core. It stores electrical energy in the form of a magnetic field induced by an EMF. Inductors generate inductance. It is basically used for filtering the input signal passing through them. It’s mainly found in FM transmitters, TVs, Battery chargers, etc. in almost all electronic devices. The standard unit of inductance is henry , denoted by H.
  • Resistor:- Resistor is a semiconductor device whose task is to oppose the flow of electric current. Its ability to reduce the flow of current is called resistance. The resistance value is measured in standard unit Ohms. Resistors are of two types:- 1. Fixed resistors and 2.Variable Resistors under which comes potentiometers, presets.
active and passive components


active and passive components
  • Capacitor:- Capacitor is a passive component that stores electrical energy in the form of the electric field. Capacitors have a medium between two plates to store the electric charge. This medium is called Dielectric. The ability of a capacitor to store the charge is capacitance. The capacitance of a capacitor is measured in farads and denoted by uf.

There are many types of capacitors like Radial, metallic, polyester, ceramic, etc. based on their scope of use. But, basically, they are classified as Polarised and Non-Polarised.

Polarised are ones having negative and positive terminal.

Non-Polar are ones without a negative and positive terminal.

  • Transformer:- It is a passive device works on the principle of inductance and does the task of voltage step-up or step -down. It has two coils primary for input and secondary for output.
active and passive components
  • Thermister:- It is also a type of resistor which is temperature-dependent. Its resistance depends on the temperature. NTC and PTC are an example.
active and passive components

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Hello everyone, I am Abhishek Sharma. I am an Engineer, a passionate blogger, an Electronics circuit designer, and the Founder of Electroinvention. I love making cool electronics circuits and gadgets. I also do SEO(Search Engine Optimization) work and also, I am a student of Computer Science.

4 Replies to “Active and Passive Components | Basic Electronics

      1. you mention that active components are those that can modify signal into some extend or amplify or inverting …what about transformer is used to transform signal from higher to lower or vice versa …can u explain more about that thank you?

        1. Hi Brian, Very good question. Transformers doesn’t change signal from one form to another, they only increase or decrease its amplitude but does not generate or inject any additional signal or power. It just increases or decreases voltage, but the signal and power remain the same.
          Transformer is a device which have pairs of inductors and works over the concept of mutual induction.

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