Wires
Electronic Component | Circuit Symbol | Description |
Wire |
Used to connect one component to another.
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Wires Joined |
One device may be connected to another
through wires. This is represented by drawing “blobs” on the point where
they are shorted.
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Unjoined Wires |
When circuits are drawn some wires may
not touch others. This can only be shown by bridging them or by drawing
them without blobs. But bridging is commonly practised as there will not
arise any confusion.
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Power Supplies
Electronic Component | Circuit Symbol | Description |
Cell |
Used to provide a supply for a circuit.
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Battery |
A battery has more than a cell and is
used for the same purpose. The smaller terminal is negative and the
larger one is positive. Abbreviated as ‘B’.
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DC Supply |
Used as a DC power supply, that is, the current will always flow in one direction.
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AC Supply |
Used as AC power supply, that is, the current will keep alternating directions.
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Fuse |
Used
in circuits where a probability of excessive current flows. The fuse
will break the circuit if excessive current flows and saves the other
devices from damage.
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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 mutual inductance is used to obtain power. Abbreviated as
‘T’.
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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 it is applied in radio circuits and power circuits.
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Resistor
Electronic Component | Circuit Symbol | Description |
Resistor |
A resistor is used to restrict the amount of current flow through a device. Abbreviated as ‘R’.
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Rheostat |
A rheostat is used to control the current flow with two contacts. Applicable in controlling lamp brightness, capacitor charge rate, etc.
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Potentiometer |
A potentiometer
is used to control the voltage flow and has three contacts. Have
applications in changing a mechanical angle change to an electrical
parameter. Abbreviated as ‘POT’.
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Preset |
Presets
are low cost variable resistors that are used to control the charge
flow with the help of a screw driver. Applications where the resistance
is determined only at the end of the circuit design.
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Capacitor
Electronic Component | Circuit Symbol | Description |
Capacitor |
Capacitor
is a device that is used to store electrical energy. It consists of two
metals plates that are separated by a dielectric. It is applicable as a
filter, that is, to block DC signals and allow AC signals. Abbreviated
with the letter ‘C’.
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Capacitor - Polarized |
Capacitor can be used in a timer circuit by adding a resistor.
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Variable Capacitor |
Used to vary the capacitance by turning
the knob. A type of variable capacitor is the trimmer capacitor that is
small in size. The notations are all the same.
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Diode
Electronic Component | Circuit Symbol | Description |
Diode |
A diode is used to allow electric current to flow in only one direction. Abbreviated as ‘D’.
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Light Emitting Diode (LED) |
LED is used to emit light when a current is passed through the device. It is abbreviated as LED.
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Zener Diode |
After a breakdown voltage, the device allows current to flow in the reverse direction as well. It is abbreviated as ‘Z’.
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Photo Diode |
Photodiode works as a photo-detector and converts light into its corresponding voltage or current.
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Tunnel Diode |
Tunnel Diode is known for its high-speed operation due to its application in quantum mechanical effects.
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Schottky Diode |
The Schottky Diode is known for its large forward voltage drop and hence has great applications in switching circuits.
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Transistor
Electronic Component | Circuit Symbol | Description |
NPN Transistor |
This is a transistor with a layer of
P-doped semiconductor fixed between two layers of N-doped semiconductors
that act as the emitter and collector. Abbreviated as ‘Q’.
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PNP Transistor |
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 as ‘Q’.
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Phototransistor |
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 can
also act as a photodiode if the emitter is not connected.
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Field Effect Transistor |
Like a transistor, a FET
has three terminals, the Gate, Source and Drain. The device has an
electric field that controls the conductivity of a channel of one type
charge carrier in a semiconductor substance.
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N-Channel Junction FET |
The Junction Field Effect 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 pieces of P-type silicon material diffused on each sides of its
middle part, forming P-N junctions.
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P-Channel Junction FET |
P-channel JFET is similar in
construction to N-channel JFET except that P-type semiconductor base is
sandwiched between two N-type junctions. In this case majority carriers
are holes.
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Metal Oxide Semiconductor FET | Given Below |
Abbreviated as MOSFET. MOSFET is a three terminal device and is controlled by a gate bias. It is known for its low capacitance and low input impedance.
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Enhancement MOSFET |
The enhancement 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 a current results
when a voltage is applied across the drain-source terminals. Abbreviated
as e-MOSFET.
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Depletion MOSFET |
In the depletion-mode construction a
channel is physically constructed and a current between drain and source
is due to voltage applied across the drain-source terminals.
Abbreviated as d-MOSFET.
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Logic Gates
Gate | Standard Symbol | IEC Symbol | Description |
AND Gate |
If all the inputs of an AND gate are
HIGH, then the output will also be HIGH. If any one of them is LOW, the
output will also be LOW.
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NAND Gate |
Short form for NOT AND Gate. Of all the
inputs are HIGH, the output will be LOW. If any one input is LOW, the
output will be HIGH.
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OR Gate |
If any one of the input is HIGH, the output will also be HIGH. If both inputs are LOW, the output will also be LOW.
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NOR Gate |
Short form for NOT OR. If both inputs are LOW, the output will also be LOW. For other cases, the output will be HIGH.
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EX-OR Gate |
Short form for Exclusive NOR. If both
inputs are either in LOW state r HIGH state, the output will be LOW. If
both inputs are different, the output will be HIGH.
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EX-NOR Gate |
Short form for Exclusive NOT OR. If both
the inputs are the same, the output will be HIGH. If both are
different, the output will also be different.
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NOT Gate |
Also known as the inverter Gate. There
is only one input for this gate. If the input is HIGH, the output will
be LOW. If the input is LOW, the output will be HIGH.
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Meters
Electronic Component | Circuit Symbol | Description |
Voltmeter |
Voltmeter is used to measure the voltage at a certain point in the circuit.
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Ammeter |
An Ammeter is used to measure the current that passes through the circuit at a particular point.
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Galvanometer |
A galvanometer is used to measure very small currents in the order of 1 milli ampere or less.
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Ohmmeter |
Resistance of the circuit is measured using an Ohmmeter.
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Oscilloscope |
An oscilloscope is used to measure the voltage and time period of signals along with their shape display.
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Sensors
Electronic Component | Circuit Symbol | Description |
Light Dependent Resistor (LDR) |
It is abbreviated as LDR. Light Dependent Resistor
is used to convert light into its corresponding resistance. Instead of
directly measuring the light, it senses the heat content and converts it
onto resistance.
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Thermistor |
Instead of directly measuring the light,
a thermistor senses the heat content and converts it into resistance.
Abbreviated as ‘TH’.
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Switches
Electronic Component | Circuit Symbol | Description |
Push Switch |
This is an ordinary switch that passes current only upon pressing.
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Push to Break Switch |
The push to break switch is usually kept in the ON state (closed). It turns to OFF state (open) only when the switch is pressed.
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Singe Pole Single Throw Switch |
Also known as the ON/OFF switch. This switch allows the flow of current only when it is kept ON. Abbreviated as SPST.
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Single Pole Double Throw Switch |
Also known as the 2-way switch. It can
be also called as an ON/OFF/ON switch as it has an OFF position in the
center. The switch causes the flow of current in two directions,
depending on its position. It can be abbreviated as SPDT.
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Double Pole Single Throw Switch |
Abbreviated as DPST. Can also be called
as a dual ON-OFF switch. This is used to isolate between the live and
neutral connections in the main electrical line.
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Double Pole Double Throw Switch |
Abbreviated as DPDT. The switch uses a central OFF position and is applied as reversing switch for motors.
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Relay |
Relay
is abbreviated as ‘RY’. This device can easily switch a 230 Volt AC
mains circuit. It has three switching stages called Normally Open (NO).
Normally Closed (NC), and Common (COM).
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Audio and Radio Devices
Electronic Component | Circuit Symbol | Description |
Microphone |
This device is used for converting sound to its corresponding electrical energy. Abbreviated as ‘MIC’.
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Earphone |
Does the reverse process of microphone and converts electrical energy into sound.
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Loudspeaker |
Does the same operation as an earphone, but converts an amplified version of the electrical energy into its corresponding sound.
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Piezo-Transducer | It is a transducer that converts electrical energy into sound. | |
Amplifier |
Used to amplify a signal. It is mainly used to represent a whole circuit rather than just one component.
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Aerial |
This device is used to transmit/receive signals. Abbreviated as ‘AE’.
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Output Devices
Electronic Component | Circuit Symbol | Description |
Lighting Lamp |
This is used to provide light for the output.
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Indicator Lamp |
Used to convert electrical energy into light. The best example is the warning light on a car dashboard.
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Heater |
This transducer is used to change electrical energy into heat.
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Inductor |
Inductor is used to produce a magnetic
field when a certain current is passed through a coil of wire. The wire
is coiled on a soft iron core. Have applications in motors, and tank
circuits. Abbreviated as ‘L’.
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Motor |
This device is used to convert electrical energy into mechanical energy. Can be used as a generator as well. Abbreviated as ‘M’.
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Bell |
Used to produce a sound as the output, according to the electrical energy produced as the input.
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Buzzer |
It is used to produce an output sound corresponding to the electrical energy in the input.
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