Electronic Circuit Symbols : Importance & Reference Designators

Electronics is a branch of engineering, which deals with electronic and electrical circuits like Integrated circuits, Transmitters, and Receivers, etc. The electronic circuit is defined as it is a combination of various electronic components that allow the flow of electric current. The electronic components consist of two or more terminals, that are used to connect one component to another component to design a circuit diagram. The electronic components are soldered on circuit boards to make a system. If you want to focus on core side projects like electronics/ electrical, you should know the basic concepts of electronic circuit symbols and their usage. This article gives an overview of electronic circuit symbols with their functionality.

Electronic symbols are very essential to know while designing circuits for a project or while making a PCB for a project. If we don’t know the symbols of the schematic circuit, it is extremely hard to create a project. Here this article discusses most of the circuit symbols of electronic components and their functions. The names of circuit symbols are active, passive, wires, switches, power supplies, diodes, transistors, resistors, sensors, logic gates, etc.

What is a Circuit Diagram?

A circuit diagram can be defined as a graphical representation of an electronic circuit. This diagram includes different electronic components with standardized representations of symbols when a symbolic circuit uses simple component images. Not like a layout or block diagram, an electronic circuit diagram illustrates the actual connections. An electronic circuit provides the whole lane for the flow of current.

This circuit includes three fundamental things to function like a voltage source, a conductive lane to facilitate the flow of current, and a bulb that uses the flow of current to function. Apart from this, an electronic circuit includes a number of electronic components to provide different functionalities which illustrated the relative location of all the elements with their connections.

What are Electronic Circuit Symbols?

Electronics circuit symbols are represented virtually with the help of circuit diagrams. In every circuit, there are standard symbols that are used to signify the components. There are different electronic circuits symbols are used to signify basic electronic devices. The circuit symbols are mostly used to draw the electronic circuits like switches, wires, sources, ground, resistor, capacitor, diodes, inductors, logic gates, transistors, amplifiers, transformer, antenna, etc. These electrical and electronics circuit symbols are used in circuit diagrams to explain how a circuit is interconnected.

Electronic circuit symbols are signs or drawings or pictograms of different components to signify electronic components in a schematic diagram of an electronic circuit. Although, these component symbols change based on countries due to some common principles fixed by ANSI & IEC to signify the components.

The electronic circuit symbols mainly involve wires, power supplies, resistors, capacitors, diodes, transistors, meters, switches, sensors, logic gates, audio devices, and other components.

Importance of Electronic Circuit Symbols

Electronic symbols are mainly used for shortening the drafting as well as to understand the circuit diagram. These symbols are identical throughout the industry. The addition of a dot, line, letters, shading & numbers provides an exact meaning of a symbol. In order to understand the circuits with their associated meaning of symbols; one should know the fundamental form of different symbols.

These symbols are necessary to do the circuit designing which are represented by electronic drawings to convey the information regarding wiring, layouts, equipment location, and its details so that arrangement of components can be done easily.

Reference Designators of Components

The reference designators of different electronic components are listed below.

• The attenuator is denoted with ‘ATT’
• The bridge rectifier is denoted with ‘BR’
• The battery is denoted with ‘BT’
• The capacitor is denoted with ‘C’
• A diode is denoted with ‘D’
• Fuse is denoted with ‘F’
• The integrated circuit is denoted with ‘IC’ or ‘U’
• Jack connector is denoted with ‘J’
• The inductor is denoted with ‘L’
• The loudspeaker is indicated with ‘LS’
• The plug is indicated with ‘P’
• The power supply is indicated with ‘PS’
• Transistor is indicated with ‘Q’ or ‘TR’
• The resistor is indicated with ‘R’
• The switch is indicated with ‘S’ or ‘SW’
• The transformer is denoted with ‘T’
• The test point is denoted with ‘TS’
• A variable resistor is indicated with ‘VR’
• The transducer is indicated with ‘X’
• Crystal is indicated with XTAL
• Zener diode is indicated with ‘Z’ or ‘ZD’

Electronic Circuit Symbols for Digital Logic Schematics

Digital logic schematic symbols include the following.

SR Flip-Flop

It is a bistable device and the main function of this is to store 1-bit data on its 2-complementary outputs.

JK Flip-Flop

In JK FF (Jack Kilby), the ‘J’ letter is used for Set as well as the ‘K’ letter is used for Reset through internal feedback

D Flip-Flop

In D Flip-flop, D stands for Delay or Data, is one kind of flip-flop with a single input which toggles among its 2- complementary o/ps

Data Latch

Data latch is used to store 1-bit data on its only input once enable pin (EN) is LOW & gives the data bit output clearly once the EN pin is HIGH

4-1 Multiplexer

A Multiplexer is used to transmit the data through one of its inputs pins to a particular output line

1-4 Demultiplexer

A Demultiplexer is used to transmit the data through its single input pin to one of the different output lines

Wires

A wire is a two-terminal, single, and flexible material, that allows the flow of power through it. These are mainly used to connect the power supplies to the PCB( Printed Circuit Board) and in between the components. The different types of wires will be as

Wires: A single wire with two terminals will pass the current from one component to another.

Wires Jointed: When two or more wires are connected that is called as wires jointed. The joining or shorted of wires at one point is indicates the “blob”.

Wires not Jointed: In complex circuit diagrams, some wires may not connect with others, in this case, bridging is commonly utilized.

Electronic Circuit Symbols for Power Supplies

A Power supply/ power supply unit is an electronic device, that supplies electric energy to an electrical load. The flow of an electric current will be measured in terms of Watts. The function of the power supply is, it converts energy from one form to another according to our requirement. The various types of power supplies are

Cell Circuit: Supplies electrical energy from a larger terminal (+) positive sign.

Battery Circuit: A Battery is two or more cells, the function of the battery circuit is the same as the cell circuit.

DC Circuit Symbol: Direct current (DC) always flows in one direction.

AC Circuit Symbol: AC (Alternating Current) flows periodically reverses direction.

Fuse Circuit: The fuse will flow sufficient current and it is used to provide overcurrent protection.

Transformer: It is used to produce AC power supply, energy is transferred in between primary and secondary coils in the form of mutual inductance.

Solar cell: It will convert light energy into electrical energy.

Earth: It supplies the 0V to the circuit that will connect to the earth.

Voltage Source: It will supply voltage to the circuit elements.

Current Source: It will supply current to the circuit elements.

AC Voltage Source: It will supply the AC voltage to the circuit elements.

Controlled Voltage Source: It generates controlled voltage to the circuit elements.

Controlled Current Source: It generates controlled current to the circuit elements.

Resistors

A Resistor is a passive element that opposes current flow in a circuit. It is a two-terminal element, dissipates its energy in the form of heat. The resistor will damage due to the overflow of electric current through it. Resistance is measured in units of ohms and resistance, resistor color code calculator is used to calculate the value of the resistor according to its colors.

Resistor: It is a two-terminal component, that restricts the flow of current.

Rheostat: It is a two-terminal component, that is used to adjust the flow of current.

Potentiometer: A potentiometer is a three-terminal component that will adjust the voltage flow in the circuit.

Preset: Preset is a low-cost adjustable resistor that operates by using small tools like Screwdrivers.

Capacitors

A Capacitor generally referred to as a condenser, is a two-terminal passive component that will capable of storing energy in the form of electricity. These are the rechargeable batteries mainly used in the power supply. In the capacitors, electrical plates differ by a dielectric medium, and these act like a filter that allows only AC signals and blocks DC Signals. The capacitors are classified into various types that are discussed below.

Capacitor: A capacitor is used to store the energy in electrical form.

Polarized Capacitor: Stores electrical energy these must be a one way round.

Variable Capacitor: These capacitors are used to control the capacitance by adjusting the Knob.

Trimmer Capacitor: These capacitors are used to control the capacitance by using a Screwdriver or similar tools.

Diodes

A Diode is an electronic component with two terminals that are anode and cathode. It allows electron current flow from the cathode to anode but it blocks another direction. The diode will have low resistance in one direction and high resistance in another direction. The diodes are classified into various types that are discussed below.

Diode: A diode allows the current flow in one direction.

Light Emitting Diode: It will emit the light when the electric current flows through it.

Zener Diode: It will allow a constant electric current after the breakdown voltage.

Photo Diode: Photodiode will convert light into respective current or voltage.

Tunnel Diode: The tunnel diode is used for very high-speed operations.

Schottky Diode: Schottky diode is for forwarding low voltage drop.

Transistors

The transistors are invented in 1947 at Bell Laboratories to replace vacuum tubes, which will control the flow of current and voltage in the circuits. It is a three-terminal device and amplifies the current, transistors plays an important role in all modern electronics.

NPN transistor: A P-type doped semiconductor material is placed in between two N-type semiconductor materials. The terminals are the emitter, base, and collector.

PNP transistor: A N-type doped semiconductor material is placed in between two P-type semiconductor materials. The terminals are an emitter, base, and collector.

Phototransistor: It is similar to bipolar transistors, but it converts light to current.

Field Effect Transistor: FET controls the conductivity with the help of an electric field.

N-channel JFET: The Junction Field Effect Transistors are simple of FET for switching.

P-channel JFET: P-type semiconductor is placed in between N-type junctions.

Enhancement MOSFET: Similar to MOSFET but an absence of conducting channel.

Depletion MOSFET: The current flows from source to drain terminal.

Meters

A Meter is an instrument used for measuring voltage and current flow in electrical and electronic components. These are used to measure the resistance and capacitance of the electronic components.

Voltmeter: It is used to measure voltage.

Ammeter: It is used to measure current.

Galvanometer: It is used to measure small currents.

Ohmmeter: It is used to measure the electrical resistance of a particular resistor.

Oscilloscope: It is used to measure the voltage with respect to time for signals.

Switches

A Switch is an electrical/electronic component that will connect electrical circuits when the switch is closed, otherwise, it will break an electrical circuit when the switch is open.

Push switch: It will pass the current flow when the switch is pressed.

Push to break switch: It will block the current flow when the switch is pressed.

Single pole single throw switch (SPST): Simply, it is an ON/OFF switch that allows flow only when the switch is in ON.

Single pole double throw switch (SPDT): In this type of switch current flows in two directions.

Double pole single throw switch (DPST): It is a dual SPST switch, mainly used for electrical lines.

Double pole double throw switch (DPDT): It is a dual SPDT switch.

Relay: A relay is a simple electromechanical switch made up of an electromagnet & a set of contacts. These are found hidden in all sorts of devices.

Audio Devices

These devices convert an electric signal into sound signals and vice versa, which will be audible to humans. These are input/output electronic components in the circuit diagram.

Microphone: converts sound or noise signal to an electrical signal.

Earphone: converts an electrical signal to a sound signal.

Loudspeaker: converts the electrical signal to sound signal but it will amplify version.

Piezo- transducer: converts flow of electrical energy to sound signal.

Bell: It converts the electrical signal to a sound signal.

Buzzer: converts an electrical signal to a sound signal.

Sensors

Sensors will sense or detect moving objects and devices, it will convert those signals into electrical or optical. For example, a temperature sensor is used to sense the temperature present in the room. The various types of sensors are

Light-dependent Resistor: These sensors will sense light.

Thermistor: These sensors will sense heat or temperature.

Logic Gates

Logic gates are the main building blocks in the digital circuits, logic gates will have two or three inputs and a single output. The output produced by logic gates based on a certain logic. Basic Logic gate values represent in binary if we observe their truth tables.

AND Gate: The output value is HIGH when two inputs are HIGH.

OR Gate: The output value is HIGH when one of the inputs is HIGH.

NOT Gate: The output is the complement of the input.

NAND Gate: The complement of the AND gate is a NAND gate.

NOR Gate: The complement of the OR gate is a NAND gate.

X-OR Gate: The output is HIGH when an odd number of HIGH occurs in its inputs.

X-NOR Gate: The output is HIGH when an even number of HIGH occurs in its inputs.

Electronic Circuit Symbols for Other Components

These are some of the electronic/electrical components that are utilized in an electronic circuit or electrical circuit design.

Lighting Lamp: It is a bulb that will glow when a certain current flows.

Indicator Lamp: It will convert electricity to light.

Inductor: It will generate a magnetic field when current flows through it.

Antenna: It is used to transmit and receive radio signals.

Phototransistor

A phototransistor is a device used to convert the energy from light to electrical to generate both voltages as well as current.

Opto – Isolator

This component transmits electrical signals among two isolated circuits with the help of light. These are used to avoid high voltages which affect the system by getting the signal.

Operational Amplifier

An operational amplifier or op-amp is used to amplify the variation between the two inputs to generate a voltage gain that is 100,000 times higher than the difference. The o/p voltage cannot be high as compared with the power-supply voltages.

7 Segment Display

There are several display devices are available in the market where 7-segment is one of the types of display. In this, each display includes seven separate light-emitting diodes which are arranged in a model to display 0 to 9 numbers & an additional LED is used for the decimal point.

Motor

A motor is a transducer that changes the energy from electrical to kinetic.

Solenoid

A wire coil that is used to create a magnetic field once the current flows through it is known as a solenoid. It includes an iron core within the coil which is used as a transducer to change the energy from electrical to mechanical by dragging on something.

Variable Resistor

This resistor includes two contracts that are used to manage the flow of current. For instance, motor speed control, controlling the brightness of the lamp, charge flow rate adjustment into a capacitor within a timing circuit.

Thus, this is all about electronic symbols for circuits. Hope this article gives you brief information by reading the above article. Furthermore, for any queries regarding this article or electronics projects, please share your valuable suggestions by commenting in the comment section below. Here is a question for you, what are active and passive components?