Electrical and Electronic Components – Functions & Symbols

Component Image

Component Symbol

Component Name Description/Function

Antenna

Antenna is a device for converting radio frequency (RF) current from a radio transmitter into an electromagnetic signal (radio wave) radiated into space, or for capturing a small portion of the electromagnetic wave from space and then feeding it into a receiver for amplification.

BatteryA battery is a device consisting of one or more cells that produces electricity from a chemical reaction and is used as a source of power.

Capacitor

A capacitor is an electronic component made up of two conductors (plates), separated by a dielectric or insulating material, which accumulates electric charge when connected to a power source. Common uses for capacitor:- Stores electric charge. Acts as a filter to smooth out variations in a direct

current. Blocks DC and permits AC in a circuit. Couples or bonds electrical signals from one part

of the circuit to another.

Fixed or Non-polarized Capacitor

A capacitor with no implicit polarity and, therefore, can be connected either way in a circuit.

Polarized Capacitor A capacitor with positive and negative leads and can be connected only one way in a circuit.

Variable or Tuning Capacitor

A capacitor whose capacitance may be intentionally and repeatedly changed mechanically or electronically. Used mostly in radio tuning circuits, hence, the name tuning capacitor.

Trimmer/Padder

A miniature variable capacitor designed for providing extremely small increases in capacitance. It is a trimmer when connected in parallel with another capacitor and a padder when connected in series with another capacitor.

Crystal

A wafer of natural quartz or any piezoelectric material having a definite thickness that vibrates to create an electrical signal with a very precise frequency. Its main uses are in oscillator circuits, clocks, radios, computers and cellphones.

Diode A semiconductor component which allows current to flow through it in only one direction. When the correct voltage polarity is applied, the diode is in a “forward bias” condition, and when the polarity is incorrect, it is in a “reverse bias” condition. A diode can be used:- As a rectifier that converts AC to DC for a power

supply device. To detect or separate the signal from radio

frequencies. As an on/off switch that controls current.

Light Emitting Diode (LED)

A LED is a semiconductor component that emits light when current flows through it. Used mainly as an indicator lamp in many devices.

PhotodiodeA photodiode is a semiconductor component that allows current flow when exposed to light.

Zener Diode

A Zener diode is a special kind of diode which allows current to flow in the forward direction same as an ideal diode, but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, " or "Zener voltage."

Fuse

A fuse is a protective device having a short length of wire that melts or blows when the current that passes through it exceeds a specified or predetermined value.

Inductor

A coil or solenoid that generates magnetic field that induces or creates voltage. Inductor has two types: an air core whereby it is just a wound of wire and a magnetic core which is a coil of wire wound on a ferrite.

Variable Inductor

An inductor with a core that can be moved into or out of the coil, increasing or decreasing the number of turns of a coil, which in turn increases or decreases the inductance.

Integrated Circuit (IC)

Also called a chip, an IC is a miniaturized electronic circuit consisting of several interconnected active devices (transistors, diodes) and passive components (resistors, capacitors, etc.) fabricated together on a thin substrate of semiconductor material (usually a silicon).

Operational Amplifier (Op Amp)

Op Amp is a form of linear IC that has two inputs, called inverting and non-inverting, and a single-ended output which produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals.

LoudspeakerA loudspeaker (or "speaker") is a transducer that produces sound in response to an electrical audio signal input.

MeterA meter is an electrical or electronic measuring instrument having a dial or digital display as an indicator.

AmmeterAmmeter is a measuring instrument used to measure electric current in a circuit. Its unit of measurement is called ampere (A).

OhmmeterAn ohmmeter is a measuring instrument used to measure the electrical resistance. The unit of measurement is called ohm (Ω).

Voltmeter

A voltmeter is a measuring instrument used to measure the potential difference or voltage between two points in an electric circuit. The unit of measurement is called volt (V).

MicrophoneA microphone is a transducer or sensor that converts sound into an electrical signal.

Relay

A relay is an electromechanical device having one or more contacts that are opened and closed by a magnetic field. This magnetic field is generated by its own built-in electromagnet that can be activated by an external circuit.

Resistor

A resistor is an electronic component that resists or reduces the flow of current in a circuit. There are two kinds, fixed and variable. A variable resistor has a resistance track made of carbon or cermat (a mixture of metal and ceramic) with a wiper that slides along the track to pick off selected voltages.

Potentiometer

A potentiometer is a variable resistor with three terminals, two of which are connected to the voltage source and the third one to the wiper to select a specific voltage from that source.

Rheostat

A rheostat is a variable resistor with two terminals, one of which goes to one end of the track and the other goes directly to the wiper to vary the level of the source.

Thermistor

A thermistor is a temperature-sensitive resistor having a high resistance when it’s cold and a very low resistance when it’s heated. Usual application is in transistor bias-stabilization circuits and also widely used as inrush current limiters, temperature sensors, & self-regulating heating elements.

Thyristor

A thyristor is a semiconductor device that consists of four alternating layers of N-type and P-type material and functions as a bistable switch – it starts conducting when its gate receives a pulse of current.

Transformer

A transformer is a device consisting of two or more coils coupled together by magnetic induction that transfers electrical energy from one circuit to another. Usual application is to convert a 220-volt AC line into a lower secondary winding voltage.

Transistor

A transistor is an active semiconductor device that controls the flow of electric current and is used in a variety of applications such as a switch, amplifier, rectifier and oscillator. It has three electrical connections or electrodes which are called base, emitter and collector.

Phototransistor

A phototransistor is a light-sensitive transistor. It is an ordinary transistor that conducts electric current when light shines on it. Its base is usually left unconnected in a circuit.