Wire Symbols
Electronic
Circuit Symbol
Description
Component
Used to connect one component to
Wire
another.
Wire Circuit Symbol
Wires Joined
One device may be connected to
another through wires. This is
represented by drawing “blobs” on the
point where they are shorted.
Wires Joined Circuit Symbol
Unjoined
When circuits are drawn some wires
Wires
may not touch others. This can only be
shown by bridging them or by drawing
them without blobs. But bridging is
Wires Not Joined Circuit
commonly practised as there will not
Symbol
arise any confusion.
Power Supply Symbols
Electronic
Circuit Symbol
Description
Component
Cell
Used to provide a supply for a circuit.
Cell Circuit Symbol
Battery
A battery has more than a cell and is
used for the same purpose. The smaller
terminal is negative and the larger one
Battery Circuit Symbol
DC Supply
is positive. Abbreviated as ‘B’.
Used as a DC power supply, that is, the
current will always flow in one
direction.
DC Supply Circuit Symbol
AC Supply
Used as AC power supply, that is, the
current will keep alternating directions.
AC Supply Circuit Symbol
Fuse
Used in circuits where a probability of
excessive current flows. The fuse will
break the circuit if excessive current
Fuse Circuit Symbol
flows and saves the other devices from
damage.
Transformer
Used as an ac power supply. Consists
of two coils, the primary and secondary
that are linked together through an iron
core. There is no physical connection
between the two coils. The principle of
Transformer Circuit Symbol
mutual inductance is used to obtain
power. Abbreviated as ‘T’.
Earth/Ground
Used in electronic circuits to represent
the 0 volts of the power supply. It can
also be defined as the real earth , when
Earth Circuit Symbol
it is applied in radio circuits and power
circuits.
Resistor Symbols
Electronic
Circuit Symbol
Description
Component
A resistor is used to restrict the
Resistor
amount of current flow through a
device. Abbreviated as ‘R’.
Resistor Circuit Symbol
Rheostat
A rheostat is used to control the
current flow with two contacts.
Applicable in controlling lamp
Rheostat Circuit Symbol
Potentiometer
brightness, capacitor charge rate, etc.
A potentiometer is used to control the
voltage flow and has three contacts.
Have applications in changing a
Potentiometer Circuit
mechanical angle change to an
Symbol
electrical parameter. Abbreviated as
‘POT’.
Preset
Presets are low cost variable resistors
that are used to control the charge flow
with the help of a screw driver.
Preset Circuit Symbol
Applications where the resistance is
determined only at the end of the
circuit design.
Capacitor Symols
Electronic
Circuit Symbol
Description
Component
Capacitor is a device that is used to
Capacitor
store electrical energy. It consists of
two metals plates that are separated by
Capacitor Circuit Symbol
a dielectric. It is applicable as a filter,
that is, to block DC signals and allow
AC signals. Abbreviated with the letter
‘C’.
Capacitor –
Capacitor can be used in a timer circuit
Polarized
by adding a resistor.
Capacitor-Polarised Circuit
Symbol
Variable
Used to vary the capacitance by turning
Capacitor
the knob. A type of variable capacitor
is the trimmer capacitor that is small in
Variable Capacitor Circuit
size. The notations are all the same.
Symbol
Diode Symbols
Electronic
Circuit Symbol
Description
Component
Diode
A diode is used to allow electric
current to flow in only one direction.
Abbreviated as ‘D’.
Diode Circuit Symbol
Light Emitting
LED is used to emit light when a
Diode (LED)
current is passed through the device.
It is abbreviated as LED.
LED Circuit Symbol
Zener Diode
After a breakdown voltage, the
device allows current to flow in the
reverse direction as well. It is
Zener Diode Circuit Symbol
Photo Diode
abbreviated as ‘Z’.
Photodiode works as a photodetector and converts light into its
corresponding voltage or current.
Photo Diode Circuit Symbol
Tunnel Diode
Tunnel Diode is known for its highspeed operation due to its application
in quantum mechanical effects.
Tunnel Diode Circuit Symbol
Schottky Diode
The Schottky Diode is known for its
large forward voltage drop and hence
has great applications in switching
Schottky Diode Circuit
circuits.
Symbol
Transistor Symbols
Electronic
Component
Circuit Symbol
Description
This is a transistor with a layer of
NPN Transistor
P-doped semiconductor fixed
between two layers of N-doped
semiconductors that act as the
emitter and collector. Abbreviated
Transistor NPN Circuit Symbol
PNP Transistor
as ‘Q’.
This is a transistor with a layer of
N-doped semiconductor fixed
between two layers of P-doped
semiconductors that act as the
emitter and collector. Abbreviated
Transistor PNP Circuit Symbol
Phototransistor
as ‘Q’.
The working of a
phototransistoris similar to that of
a bipolar transistor with a
difference that it converts light into
its corresponding current. The
Phototransistor Circuit Symbol
phototransistor can also act as a
photodiode if the emitter is not
connected.
Field Effect
Like a transistor, a FET has three
Transistor
terminals, the Gate, Source and
Drain. The device has an electric
Field Effect Transistor Circuit
Symbol
field that controls the conductivity
of a channel of one type charge
carrier in a semiconductor
substance.
N-Channel
The Junction Field Effect
Junction FET
Transistor (JFET) is the simplest
type of FET with applications in
Switching and voltage variable
resistor. In an N-channel JFET an
N-type silicon bar has two smaller
n-channel Junction Field Effect
pieces of P-type silicon material
Transistor (JFET) Circuit
diffused on each sides of its middle
Symbol
part, forming P-N junctions.
P-Channel
P-channel JFET is similar in
Junction FET
construction to N-channel JFET
except that P-type semiconductor
p-channel Junction Field Effect
Transistor (FET) Circuit
Symbol
Metal Oxide
Given Below
base is sandwiched between two Ntype junctions. In this case majority
carriers are holes.
Abbreviated as MOSFET.
Semiconductor
MOSFET is a three terminal
FET
device and is controlled by a gate
bias. It is known for its low
capacitance and low input
impedance.
Enhancement
The enhancement MOSFET
MOSFET
structure has no channel formed
during its construction. Voltage is
applied to the gate, so as to develop
a channel of charge carriers so that
e-MOSFET Circuit Symbol
a current results when a voltage is
applied across the drain-source
terminals. Abbreviated as eMOSFET.
Depletion
In the depletion-mode construction
MOSFET
a channel is physically constructed
and a current between drain and
source is due to voltage applied
across the drain-source terminals.
d-MOSFET Circuit Symbol
Abbreviated as d-MOSFET.
Logic Gate Symbols
Gate
Standard Symbol
IEC Symbol
Description
If all the
AND
inputs of an
Gate
AND gate are
HIGH, then
the output
AND GATE Symbol
AND Gate IEC Symbol
will also be
HIGH. If any
one of them is
LOW, the
output will
also be LOW.
NAND
Short form for
Gate
NOT AND
Gate. Of all
the inputs are
HIGH, the
NAND Gate Symbol
NAND Gate IEC Symbol
output will be
LOW. If any
one input is
LOW, the
output will be
HIGH.
OR
If any one of
Gate
the input is
HIGH, the
output will
also be HIGH.
OR Gate Symbol
OR Gate IEC Symbol
If both inputs
are LOW, the
output will
also be LOW.
NOR
Short form for
Gate
NOT OR. If
both inputs
are LOW, the
output will
NOR Gate Symbol
NOR Gate IEC Symbol
also be LOW.
For other
cases, the
output will be
HIGH.
EX-
Short form for
OR
Exclusive
Gate
NOR. If both
inputs are
either in
EX-OR Gate Symbol
EX-OR Gate IEC Symbol
LOW state r
HIGH state,
the output
will be LOW.
If both inputs
are different,
the output
will be HIGH.
EX-
Short form for
NOR
Exclusive
Gate
NOT OR. If
both the
inputs are the
EX-NOR Gate Symbol
EX-NOR Gate IEC Symbol
same, the
output will be
HIGH. If both
are different,
the output
will also be
different.
NOT
Also known
Gate
as the inverter
Gate. There is
only one input
for this gate.
NOT Gate Symbol
NOT Gate Symbol
If the input is
HIGH, the
output will be
LOW. If the
input is LOW,
the output
will be HIGH.
Meters
Electronic
Circuit Symbol
Description
Component
Voltmeter is used to measure the
Voltmeter
voltage at a certain point in the
circuit.
Voltmeter Circuit Symbol
Ammeter
An Ammeter is used to measure the
current that passes through the circuit
at a particular point.
Ammeter Circuit Symbol
Galvanometer
A galvanometer is used to measure
very small currents in the order of 1
milli ampere or less.
Galvanometer Circuit
Symbol
Ohmmeter
Resistance of the circuit is measured
using an Ohmmeter.
Ohmmeter Circuit Symbol
Oscilloscope
An oscilloscope is used to measure
the voltage and time period of signals
along with their shape display.
Oscilloscope Circuit Symbol
Sensor Symbols
Electronic
Circuit Symbol
Description
Component
It is abbreviated as LDR. Light
Light
Dependent Resistor is used to convert
Dependent
light into its corresponding resistance.
Resistor
(LDR)
Instead of directly measuring the light,
LDR Circuit Symbol
it senses the heat content and converts
it onto resistance.
Thermistor
Instead of directly measuring the light,
a thermistor senses the heat content
and converts it into resistance.
Thermistor Circuit Symbol
Abbreviated as ‘TH’.
Switch Symbols
Electronic
Circuit Symbol
Description
Component
This is an ordinary switch that passes
Push Switch
current only upon pressing.
Push Switch Circuit Symbol
Push to Break
The push to break switch is usually
Switch
kept in the ON state (closed). It turns
to OFF state (open) only when the
Push to Break Switch Circuit
switch is pressed.
Symbol
Singe Pole
Also known as the ON/OFF switch.
Single Throw
This switch allows the flow of
Switch
current only when it is kept ON.
On Off Switch (SPST) Circuit
Abbreviated as SPST.
Symbol
Single Pole
Also known as the 2-way switch. It
Double Throw
can be also called as an ON/OFF/ON
Switch
switch as it has an OFF position in
2-Way Switch (SPDT) Circuit
Symbol
the center. The switch causes the
flow of current in two directions,
depending on its position. It can be
abbreviated as SPDT.
Double Pole
Abbreviated as DPST. Can also be
Single Throw
called as a dual ON-OFF switch. This
Switch
is used to isolate between the live and
Dual On-Off Switch (DPST)
Circuit Symbol
neutral connections in the main
electrical line.
Double Pole
Abbreviated as DPDT. The switch
Double Throw
uses a central OFF position and is
Switch
applied as reversing switch for
motors.
DPDT Circuit Symbol
Relay is abbreviated as ‘RY’. This
Relay
device can easily switch a 230 Volt
AC mains circuit. It has three
switching stages called Normally
Open (NO). Normally Closed (NC),
Relay Circuit Symbol
and Common (COM).