Electronics and Electrical Symbols

Electronic and Electrical Symbols are very important in Electrical and Electronics Engineering which virtually represents the actual components in a circuit.In this post, we will be showing different electrical and electronic engineering related symbols and schematic of the circuits and components with description.

RESISTORS SYMBOLS

RESISTOR TYPES & SYMBOL

It is the symbol of a fixed resistor. Both of these symbols represent a fixed resistor in NEMA & IEC standards systems.

Attenuator

An attenuator works opposite to the amplifier. It reduces the power of the signal without distorting it. It dissipates the signal’s power within its own resistor network. The symbol of attenuator is given above.
Preset Resistor
It is a variable resistor whose resistance is adjusted during manufacturing or designing of the circuit. It is not changed during normal use of the circuit. The resistance of preset resistor is changed using a screwdriver.
Non Reactive Resistor
These resistors, also known as non-inductive resistors, have pure resistance. A common wire wound resistor has inductance due to the magnetic field produced by the winding. Non-reactive resistors have special winding designs to cancel each other’s magnetic fields.
Impedance
The impedance is a complex quantity made of real & imaginary part. The real part represent the resistance & the imaginary part represents the reactance.
Heating Element
This component converts the electrical energy into heat energy. The current flow through the heating element generates heat energy due to its resistance.
Protective Resistor
These both symbols represent a protection resistor. It operates like a resistor that limits the current flow & if the current exceeds its certain limit then it blow out opening the circuit.
Memristor
Memristor or also known as memory resistor is a hypothetical non-volatile memory component whose resistance depends on the current that has been passed through it in the past. It remembers its last known resistance when it is Powered OFF/ON.
Shunt Resistor
A shunt resistor (also known as current shunt) is a resistor with low & precise resistance used to measure the current through it. The current is measured by the voltage drop across it. Thus it acts as a current sensor.
Resistor Array
Resistor array is a combination of multiple resistors in a single packaging. It contains multiple individual resistors denoted by the number in the symbols e.g 8 in this case.  The resistors are not connected together except for its one side which is connected with VCC for pull up & GND for pull down. They are used for saving space & cost of placing.

SPECIAL RESISTORS SYMBOLS

SPECIAL RESISTOR SYMBOL

It is a light dependent resistor i.e. its resistance depends on the intensity of the light. The resistance of LDR decreases with increase in the light intensity.
Thermistor
Thermistor or thermal resistor is a type of resistor whose resitance depends on its surrounding temperature. It either decrease or increase with the temperature depnding on the type of thermistor.
NTC & PTC Thermistor
NTC stands for negative temperature coefficient & PTC stands for positive temperature coefficient. The NTC Thermistor resistance decrease with increase in the temperature & denoted by –t° sign. The PTC thermistor resistance increase with increase in temperature & denoted by +t° sign.
Varistor VDR
Varistor or VDR (voltage dependent resistor) is a type of resistor whose resistance depends on the voltage applied. Its resistance varies with the change in the applied voltage. These symbols (some of them are old & new) represent varistor.
Iron Hydrogen Resistor
It is positive temperature coefficient resistor made of iron wire inside hydrogen filled bulb. Its resistance increase with temperature which is due to the increase in the current flow. The increasing resistance opposes the increase in current. Thus they are used in stabilizing circuit.
Magneto resistor
Magneto resistor or MDR (Magnetic dependent resistor) is a type of resistor whose resistance depends on the external magnetic field. It resistance changes with change in magnetic field intensity & It is a used as a magnetic sensor for sensing magnetic field.
Resistance thermometer or RTD
Resistance temperature detector (RTD) is a temperature sensor whose electrical resistance changes with the temperature. The material used in RTD’s has very accurate relation between the resistance & temperature. It can be measured by supply of constant current & the voltage drop across the resistor.

Variable & Adjustable Resistors

VARIABLE RESISTOR SYMBOL

A variable resistor also known as potentiometer or rheostate has a variable resistance. It has three terminals. The two of them have fixed resistance while the third terminal move over the resistive trace or wire to increase or decrease the resistance. They are used for increasing or decreasing  the current flow in a circuit during its normal operation.
Continuous Variable Resistor
Such type of variable resistor has a continuous resistance i.e. the sliding or rotating the contact gives out a continuous value of resistance. It can achieve infinite numbers of resistance values ranging from min to max.
Step Variable Resistor
This type of variable resistor’s resistance increase or decreases in steps . The contacts does not slide smoothley but jumps from steps . Each step movement increase or decrease a fixed amount of resistance.
Carbon pile Variable resistor
This type of variable resistor is made up of carbon discs clamped together between two metal plates. Increasing or decreasing the presure between these metal plates increases the resistance of the device.
Variable Resistor with ON/OFF switch
This type of variable resistor has a builting switch that breaks or make the contact between the two termianls.
Preset Resistor
Preset resistor is a variable resistor that is only operated during menufacturing and tuning a circuit. they are not operated during the normal use of a circuit. there design are not as rigid as a variable resitors (Potentiometer etc).

CAPACITORS & CONDENSERS SYMBOLS

CAPACITOR & CONDUNCER SYMBOL

Capacitor is an electronic component that stores energy in its electric field. It is the symbol of a generic capacitor. It is a non-polar capacitor having fixed capacitance value. It can be connected in either direction. The second symbol represents an obsolete capacitor symbols used for non-polar capacitors.
Polarized Electrolytic Capacitor
Such type of capcitors uses electrolyte as one of its electrode that is why they are polarized. The have positive and negative terminals and the top of these symbols represent the positive terminals. A polarized capacitor must be connected in circuit accordingly, otherwise it will blow up. The first two symbols are used in UK while the next two symbols in US . The 5^th symbol for capacitor is used in japan.
Variable Capacitor
This symbol represents a variable capacitance whose capacitance can be varied during normal operation. The capacitance is varied by increasing or decreasing the effective area between the plates that effects the capacitance of the capacitor. They are used in LC tuning circuits.
Trimmer Capacitor
It is also a variable capacitor whose capacitance is used to calibrate a circuit during manufacturing or troubleshooting a circuit. The capacitance of such capacitor is not noramlly changed by users during operation.
Bipolar Capacitor
They are also known as non polar electrolytic capacitor. It is made of two electrolytic capacitor in such design that they can be used in any polarity. They differ from generic ceramic non polar capacitor by having large capacitance.
Feed through Capacitor
This type of capacitor is designed for DC power supply in RF systems. It supply the pure DC signal & also filters any RF component from it.
Voltage Dependent Capacitor
The capacitance of such capacitor depend on the applied voltage. Increasing or decreasing the supply voltages changes the size of the dielectric gap between the plates which increases the capacitance.
Temperature Dependent Capacitor
These capacitors capacitance depends on its surrounding temperature. The temperature increase or decrease may increase or decrease the capacitance of the capacitor. They are used in temperature sensing application.
Differential Capacitor
It is a variable capacitor with two operate stator and one common rotor. Moving the rotor increases the capacitance in one section & simultaneously decreases it in the other section. However the total capacitance remains the same.
Split Stator Capacitor
As the name suggest, such type of variable capacitor has two set of stators that are separated at 180° . A common shaft  rotates  the rotor that has the same vanes placed 180° apart. Such capacitors do not have the 90° limitation of a generic variable capacitor.
Dual Ganged Capacitor
It is the combination of two variable capacitor. The variable rotor of these both capacitors is controlled using a single shaft. Thus they provide variable capacitance in both capacitors by moving a single rotor.
Butterfly Capacitor
Such type of variable capacitor has two separate stators opposite to each other mounted on the body of the capacitor. The rotor whose plates are also butterfly shaped, rotates between these two stators. The capacitance in such capacitor varies equally between either stator & rotor. They are used in symmetrically tuned circuits.
Tempatrimmer
Tempatrimmer or also known as thermotrimmer is a small trimmer capacitor with a variable temperature coefficient. They are used in stabilizing the drifting VFos.

INDUCTORS SYMBOLS

INDUCTOR SYMBOL

Generic Fixed Inductor
This is the symbols used for representing a generic Inductor whose inductance value is fixed. An inductor is also known by many names such as coil , choke etc. stores energy inside magnetic field.
Variable Inductor
This type of inductor has variable inductance. Its inductance can be changed during the operation of the circuit such as in radios.
Step Variable Inductor
The inductance of such variable inductor can be varied in steps rather than in a continuous manner. They have designed (fixed) value of resistance per step.
Inductor with polarity
Such inductors have a dot on one side of its terminal. The dot convention of the inductor shows the direction of the current entering the inductor & they are used while coupling inductors for maximum mutual inductance.
Iron Core Inductor
This is a type of inductor whose core is made up of iron (Ferromagnetic material). The iron core increases the inductance of the inductor due to its high magnetic permeability.
Ferrite Core Inductor
As the name suggests, these inductors have ferrite core. The ferrite material provide high magnetic permeability as well as low electrical conductivity to reduce the losses inside the core. They are used in high frequency applications.
Variable Ferrite Core Inductor
It is a type of ferrite core that has variable inductance. The inductance of such inductors is varied by screwing in & out the core inside the coil.
Preset Ferrite Core Inductor
The preset inductors are also variable inductor but there inductance is varied at the time of manufacturing or tuning a circuit. Their inductance is not changed during normal use of the circuit.
Shielded Inductor
Such type of inductors core is designed to contain its magnetic field inside. There is little to know leakage flux that could interfere with other nearby components. These are used in compact PCBs where space managing is the utmost requirement.
Electromagnet Solenoid
A solenoid is a cylindrical coil made of a conductor which produces magnetic field when electricity passes through it. It is also known as Electromagnet.
Electromagnetic Deflection Coil
Such type of coil is used in CRT (cathode ray tube) where it produces the magnetic field to deflect or change direction of the electron beam both vertically and horizontally.
Bifilar Inductor
The coil of bifilar inductor is made up of two conductors running in parallel with each other. The winding conductors can be antiparallel (reverse direction of current) to cancel the magnetic field produced by each other. They can be in parallel to double fold the magnetic field produced by the coil.
Variometer
The variometer is a variable inductor that provide a continuous change in inductance by moving the two coils inside one another that are connected in series.
Saturable Core Inductor
This type of inductor is deliberately designed to saturate its core to decrease its inductance & inductive reactance. This results in high AC current carrying capability.
Electric Motor Inductor
It is the graphical representation of the coil (winding) used inside AC machines which converts the electrical energy into mechanical energy through induction.
Analog Delay Line
It is a coil designed to produce a time delay or phase change in the analog signal. Just like digital buffers are used to produce time delay in digital signal.

FUSES, CIRCUIT BREAKER & PROTECTION

FUSE SYMBOL

Fuse
These are some of the symbolic representation of a generic fuse in any electrical circuit. A fuse is used for protection of any electrical device from overcurrent. It has a small wire or metal which melts due to large current & Opens the circuit blocking the flow of faulty currents. The IEC, IEEE & ANSI provide different representation systems.
Thermal Fuse
The symbol for a thermal fuse used in any electrical circuit diagram. A thermal fuse is a temperature sensitive switch. It operates on the temperature rather than the current unless the current is sufficient to increase the temperature above the threshold point.
Fuse Switch
This symbol represents a fused switch.  A fuse switch performs the action of switching by physically removing the fuse because the fuse is the part of the switch.
Isolator Switch Disconnector
It is a also known as disconnector switch or isolator switch is used for isolating and completely de-energizing the circuit. It is an off-load device. The symbol above represent an isolator switch.
Fuse switch Disconnector
It is the symbol for fuse switch disconnector. It is a fuse in series with a switch. It can switch the device manually and also provide the protection against overcurrent by breaking the circuit.
Protection Resistor
These both symbols represent a protection resistor. It operates like a resistor that limits the current flow & if exceeds its certain limit then it blow out opening the circuit.
Fast Blow Fuse
The symbolic representation of a fast blow fuses in any electrical circuit. Fast blow fuse instantly blow when the current exceeds beyond its maximum limit. It is the most common type of fuse used in electrical equipment which are sensitive to high current.
Slow Blow Fuse
On the contrary to fast blow fuse, the Slow blow fuse can tolerate high current for a short period of time. it will blow out after a short period of time when the current exceeds the maximum limit. Motors require huge current upon starting, a slow blow fuse can withstand this current without blowing.
Fuse with Striker
Such type of fuse is also known as striker fuse. It has a striker pin that works as an indicator for showing the fuse condition. The pin pulls out when the fuse blow.
Fuse With Alarm Contact
The symbolic representation fo fuse with alarm contact. Such fuses have a builtin alarm circuit for displaying the status of the fuse. When the fuse blow, the circuit activates and shows a light or any other indication.
Fuse with Separate Alarm Contact
This symbol represents a fuse with separate alarm contact.
3 linked Fuses with release of any Striker
This is the symbolic representation of the 3 linked fuses which releases with the release of any of the three strikers.
Oil Type Fuse
It is the symbol for oil Fuse. It is used in distribution switchgear that are immersed in the oil. The oil is used as coolant to increase its breaking capacity.
Circuit Breaker
These are all the symbols used for generic circuit breaker. Circuit breaker is an automatically operated switch that protects the appliances from short circuit or heavy load current. It opens the circuits once the current flow crosses its maximum limit.
Non Draw out Circuit Breaker
Fixed Mounted Breakers or Non draw out circuit breaker is represented by the symbol given above. This type of breaker is fixed & during maintenance, the power flow through the breaker needs to be stopped.
Draw out Circuit Breaker
Draw out circuit breaker has two parts i.e. base which is fixed & the sliding breaker which can be removed without interrupting the power flow. Such type of circuit breakers is used where continuous power is necessary even during maintenance.
Thermal Switch
A thermal switch operates on the temperature. It controls the flow of current depending on the temperature. It opens the circuit when the temperature increases above its rating & closes when the temperature drops from certain point. Above given is the symbol of thermal switch
Network Protector
A Network protector is used between the secondary terminal of the distribution transformer & the load network. Its function is to break the connection when it detects any reverse flow of current to prevent any loss.
Threaded Circuit Breaker
This symbol represents a threaded circuit breaker.
Single Pole Circuit Breaker
This symbol represents a single pole circuit breaker. It has only one Hot wire & when there is any overload or short circuit it trips.
Double Pole Circuit Breaker
This one represents a circuit breaker with two poles. Such type of circuit breakers has two separate hot wires going through it. When a short circuit or an overload occurs in any of the two hot lines, the circuit breaker trips both the lines.
Three Poles Circuit Breaker
This symbol represents circuit breaker with three poles. Such kind of breakers is used in three phase systems in industries. It connects three phases & whenever there is an overload or short circuit in any phase, the circuit breaker trips all three phases simultaneously.
Isolator Circuit Breaker
Isolator Circuit breaker is used for isolating the load from the source completely. It is an off load manual device. It has slightly less current capacity then circuit breakers. It provides a visual confirmation of an open circuit & a necessary precaution during maintenance.
Lightning Arrester / Surge Protector
It is the symbol used for lightning arrester. It is a device used for protection against lightning or high surge currents in line. It has a two terminals i.e. high voltage terminal & ground terminal. The lightning arrestor diverts the surges from lightning to the earth.
Spark Gap
These are some of the symbols used for spark gap. It is made of two conductors with small gap in between which is filled with gas. The gas ionizes when the voltage exceeds the gas breaking point & it creates a spark. It is used in spark plug for fuel ignition and as switching devices for pulse power application like discharging the capacitor at high voltage/current.
Double Spark Gap
This type of spark gap has two small gaps between the conductors which creates double spark. Above given is the symbol for double spark gap.
Surge Arrestor / Gas Discharge Tube
Surge arrestor or Gas discharge tube is made of hermetically sealed gas chamber. Whenever the voltage exceeds certain limit, an arc is formed which short circuit the whole current flow thus protecting the equipment.
Telephone Line Protector
The symbol for telephone line protector which protects the telephone line from the surges or lightning to prevent any damage to the conductor or the equipment.
Lightning Rod
This is the symbolic representation of a lightning rod. It is a metal rod placed on top of any building. This rod is connected to the ground with a conductor. When a lightning strike the building, the rod catches the lightning & transmits the power to the ground bypassing the building & preventing any damage.
Thermostat
A thermostat controls the temperature surrounding it & maintains it by switching the cooling or heating equipment on & off. The symbol for thermostat is given above.
Cartridge Circuit Breaker
The symbols shows a cartridge circuit breaker. These circuit breakers hold a cartridge fuse which breaks upon exceeding its current limit. It can be replaced easily.

SWITCHES & PUSH BUTTONS SYMBOLS

SWITCHES SYMBOL

SWITCHES SYMBOL

Generic Switch Symbol
It is the symbol of a generic switch in open condition.
Open Switch
This is a generic symbol for an open switch. A switch is a component that can break or make the circuit. An open switch represents a break circuit & it stops the flow of current through it.
Closed switch
It is a generic symbol for closed switch. a closed switch means the circuit is complete & current can flow through it.
Thermal Magnetic Switch
It is the symbol of thermal magnetic switch. it incorporates both electromagnetic  and thermal breaking. During huge current spikes, electromagnet instantaneously breaks the circuit without any delay. But its bimetallic strip provides a little delay when the current exceeds its limit.
Limit Switch
The given symbol represent a limit switch. it is operated by mechanical parts of any machine which is used in control systems. It is activated by any other objects or machines parts when it comes in contact with its actuator.
Telegraph Key
Telegraph key is represented by this symbol. It is a special electrical switch designed for transmitting text messages in Morse code. It connects & disconnects the circuit creating pulses of different length called “dots” & “dashes”.
Differential Switch
Differential switches operate on the difference between the phase line current & the neutral line current. If there is any current difference (due to fault current), then it breaks the circuit.
Pulse Counter Switch
This switch’s actuator is operated by a pulse counter. Whenever the pulse counter reaches a fixed value the switch activates and switches the circuit connected with it.
Switch SPDT
It is the symbol for single pole double throw (SPDT) switch. Such kind of switch has three terminals with one common terminal. The common terminal is connected with either one of the other two terminals.
Slide Switch SPDT
Slide switch has a slider that slides back and forth in position for making & breaking the current flow in the circuit. The symbol given is an SPDT slide switch also known as single pole double throw switch.
Switch DPST
DPDT stands for double pole single throw. It has two poles, means two different circuits can be connected to it and one throw means that it has only one ON (close loop) position. It either switches ON or OFF the two circuits at the same time.
Switch DPST One close before other
It is also a DPST Switch but such type of switch has one modified pole which closes (make contact) before the other one during closing position. They are used in specific applications where a connection needs to be made before the other one.
Switch DPDT
DPDT stands for double pole double through. It is two SPDT Switches combined with common lever. DPDT switch can switch two different circuits at the same time. In either of the two positions, each circuits has close connection with separate terminals.
Switch DPMT
DPMT stands for double pole multi throw. This switch has two poles i.e. it can switch two independent circuits. Each circuit can be switched to multiple terminals.
Switch SP4T
It is the symbol for switch having single pole and 4 throws. It has 4 position & it can switch a single circuit by connecting it with any of the 4 terminals.
Rotary Switch
It is the symbol used for rotating or rotary switch. it has knob which rotates around its axis & it switches the common terminal to any of the output terminals. Rotary switches can have multiple levels (poles) for switch multiple separate circuits & multiple throws.
On-Delay Switch
On-delay switch instantaneously switch form ON(close) to OFF(Open) position. But during siwtching from OFF position to ON postion it takes some time delay. The symbolic representation for On-Delay Switch is given above.
ON OFF Delay Switch
This type of switch has time delay function whenever it switches. Switching from ON to OFF or from OFF to ON, in both situations the switch takes some time delay.
Generic Push Button Switch
It is the symbol of a Single pole single throw generic pushbutton switch. It has an actuator which switches the circuit ON & OFF by pushing.
Rotary Closed Switch
It is the symbol of a rotary switch in closed (ON) Postion. It is a single pole switch in Make contact position. It has no automatic return position.
Rotary Open switch
It is the symbol of a rotary switch in open (OFF) Position.
NO Push Button
It is a NO (Normally Open) Push button. Normally, it remains in open(OFF) position. Pressing the pushbutton switches it into ON (Close) position but releasing the button return the switch into OFF (open) position.
NC Push Button
This is a normally close push button which remains Closed (ON position) normally. It switches into OFF position by pressing the button but after releasing, it returns to Closed position.
Push button Lockable
This is the symbol of a push button with lockable feature. It automatically return to its normal position but it can be locked in the desired position.
Positive opening Push Button mushroom head
It is a push button with mushroom head. It is positive opening switch means its contacts are open when the device is in its corresponding open position.
Positive make Contact Push Button
It is also a push button with positive make contact (Close position). Its contact closes when the position of the switch corresponds to the close position of the switch.
Timer Switch
It is the symbol for a timer switch. it basically makes and breaks contact when the timer runs out. The timer sets the timer using mechanical clockwork. It provide a time delay for specific applications.
Delayed Closing Switch
It is the symbol of a switch whose contact does not close immediately but it takes a little time delay.
Fast Closing Switch
This symbol represents a fast closing switch. This switch instantly closes (turn ON) after switching its position.
Delayed Opening Switch
It is a delayed opening switch. During switching its position form ON to OFF, its contacts are still close for some time.
Fast Opening Switch
This switch instantly opens its contacts during switching thus making a fast open situation.
Push to Make Switch
This symbol represents a push button switch in open position or also known as push to make switch. Manually pressing & holding the push button will closes its contact into ON position. After releasing the push button, the  switch return to Open condition.
Push to Break Switch
This switch is normally in close condition i.e. the circuit is complete. When you press the button and hold it, it breaks the circuit. Upon releasing the button, it returns to its normal close condition.
Push Button Limit Switch
It is a push button limit switch. Limit switch are actuated by the motion of mechanical parts of machines or other objects etc. it switches circuits that control other parts of a machine.
Push button Double Pole Limit Switch
It is also a limit switch but it has two pole i.e. it control two separate circuit. this type of switch breaks one circuit and closes the other one.
Joystick Switch
Joystick is a switch with a lever or stick connected to the base. The directional movement of the stick connects the different terminals of the switch. it is used in gaming controller pads, in cranes & trucks in the industry.
Push Button SPDT
This is a single pole double throw push button. There is no open position is this switch. It makes contact (ON state) in both positions. Pushing & holding the button will switches the circuit unto the other terminal. Releasing the button will return the contact to its original position.
Push Button DPDT
This is a double pole double throw switch. it switches two separate circuit but pressing the button will break one circuit and closes the other one. Also upon releasing the button, the switching will be reversed.
Float Switch
Float switch is a switch that controls a circuit or machine inside a tank full of liquid. It detects the level of the liquid and switches ON or OFF when the liquid level rises or fall.
Thermal Switch
Thermal switch is temperature dependent switch that switches a circuit when it crosses a preset temperature. However, it returns to its normal position when the temperature becomes normal.
NC Thermal Switch
It is a normally closed thermal switch that is in ON (close) position during room temperature. When the temperature increases above a fixed point, it breaks the circuit. when the temperature reduces below the point it switches ON the circuit.
NO Thermal Switch
It is also a thermal switch it is normally open in room temperature.  Increasing the temperature makes the contact switching it into ON position & reducing it switches it into OFF position.
Selector Switch
Selector switch is a rotary switch with two or more than 2 positions. It can switch one or more than one circuits at the same time.
Starter
Also known as electronic fluorescent starter is used to soft start the fluorescent lamp by preheating the cathode and send a controlled pulse to the lamp to start glowing.
Mercury Switch
Mercury switch has mercury inside a vessel in between the two terminals of the switch. The movement of the mercury closes & opens the circuit when the vessel is tilted. The mercury is a conductor & it connects the terminals when it touches it. Mercury switch can be used where there is motion like tilting, rolling etc.
Foot Operated Switch
This symbol represents a foot operated or foot pedal switch. it is a single pole switch which control a circuit or motor usually used in controlling heavy machinery. It has a very rugged design because it is being operated by foot.
Switch DPST BBM
It is a double pole single throw switch with break before make (BBM) mechanism. It switches two circuits but first it breaks (open) one circuit and then makes (close) the other one.
Proximity Switch
Proximity switch is a sensor that detects an object with in close range. It is non-contact sensor switch. Whenever an object comes in its range, it switches & corresponding circuit is activated. This circuit can be an alarm or counter or any type of logic circuit.
Neon Lamp Switch
This is a simple single pole single throw switch with a neon lamp. The neon lamp acts an indicator for showing the flow of current through the switch.
DIP Switch
DIP stands for dual inline package. it is made from packing multiple switches together in a dual inline package (DIP). Due to Its compact size, it is used in PCB (printed circuit).

DIODES SYMBOLS

DIDOE SYMBOL

Generic Diode
This symbol represents a generic diode or a rectifier diode. It is an electronic component made of semiconductor that allow current flow in one direction and block it in reverse direction.

Zener Diode
Zener diode is a type of diode that allows the flow of current in forward direction as well as reverse direction but when the reverse voltage reaches the breakdown voltage known as Zener voltage.

Schottky Diode
This type of diode made from of a small junction between an N-type semiconductor and a metal. It has no P-N junction like normal diodes. Due to which, it has very low forward voltage drop and fast switching because there is no capacitive junction (P-N junction).
Backward Diode
It is a type of diode that operates as a tunnel diode in forward bias & zener diode in reverse bias. but its tunneling effect & zener breakdown voltages are much reduced. It is used in rectification of a small voltage signal (0.1 to 0.6v).

Tunnel Diode
This type of diode is made from heavily doped P & N semiconductor that works on the principle of the tunneling effect. Tunneling is the phenomenon of escaping electrons between the PN junction due to heavy doping. Tunnel diode has a negative resistance region where the current decrease with increase in voltage & they are operated in this region.

PIN Diode
It is a three-layer diode where PIN stands for  P-layer, I-layer & N-layer. The ‘I‘ intrinsic semiconductor layer is placed between heavily doped P and an N-type semiconductor. The I layer blocks high voltage in reverse bias. Due to poor reverse recovery time, they are not used in high frequency applications.

LED – Light Emitting Diode
LED (Light emitting diode) is a type of P-N junction diode that emits light when configured in forward bias. It converts electrical energy into light energy & the color of the light depends on the energy gap of the semiconductor.

LED Bi-color
It is a type of LED that has two different colors of LEDs connected in antiparallel inside single package. It can emit two different colors depending on its polarity. Changing the direction of current activates the LED with another color.

Photo Diode
A photo diode converts light energy into electrical energy. When light hits the P-N Junction it creates an electron-hole pair which flows out as electrical current. this symbol represent a photo diode.

Bi-directional Photo Diode
A generic photo diode is designed to operate in only reverse bias. This type of photo diode operates in both directions.

Common Cathode Photo Diode
This type of photo diode is made from two diodes in a single package with one common terminal i.e. cathode.

TVS Diode
Transient voltage suppression diode is a type of diode that is used for suppressing high voltage spikes. It is used for protecting circuit in reversed bias (Unidirectional TVS)

Thermal Diode
Thermal diode also known as Peltier diode is a type of diode whose thermal resistance is different in one direction than in the other direction. So it allows the heat flows in one direction leaving the other side cooler.

Laser Diode
Laser diode, just like LED it converts electrical energy into light energy. but the light produced by Laser diode produces coherent light (laser beam). It is used in optical communication, laser pointer, CD drives and laser printer etc.

Magnetically Sensitive Diode (MSD)
As the name suggests, these diodes are sensitive to magnetic field. & can be used as magnetic field sensors.

Step Recovery Diode
Step recovery diode or snap diode which instantaneously blocks the current flow when its direction is reversed. This is because of the low doping of PN junction.

Varactor / Vericap Diode
Varactor or vericap diode is a voltage controlled capacitor that has a variable PN junction capacitance. Its capacitance varies by changing the reverse voltage.

Seven Segment Display
Seven segment displays is made of 7 LEDs in specific pattern. It is used for displaying decimal numerals and English alphabets. However it can be designed to display numerous characters.

5×7 LED dot Matrix Display
It is made of LEDs in 5×7 matrix pattern that is why it is known as dot matrix display. It has 5 columns and 7 rows of dot shaped LEDs next to each other. It is used for displaying characters & shapes in digital devices.

Silicon Controlled Rectifier (SCR)
SCR or thyristor is a diode made from PNPN junction. SCR is activated (to conduct current) if the forward voltage increases its forward breakdown voltage or through a positive gate pulse

Shockley Diode
It is a PNPN diode just like SCR but it does not have any gate control input. it is only triggered by applying forward voltage higher than its breakdown voltage.

Bridge Rectifier
It is also known as full wave rectifier. It is made up of four diodes that converts the AC signal into DC signal. the process of conversion from AC to DC is known as Rectification.

Variable Bridge Rectifier
This type of bridge rectifier is made up of SCR (thyristors). The thyristors switching time can be controlled by its gate input. thus this rectifier output can vary by controlling its gate input.

Three Phase Rectifier
A three phase rectifier converts the three phase electrical signal into a DC rectified output. it is a modified form a full wave bridge rectifier where 2 pair of diodes converts each phase.