Home | Site Map | Components | 555 | Symbols | Study | Books | Construct | Solder | Projects | FAQ | Links | Privacy
Electronics Club
electronicsclub.info

Circuit Symbols

Wires | Supplies | Output devices | Switches | Resistors | Capacitors | Diodes | Transistors | Audio & Radio | Meters | Sensors | Logic gates | Download symbols

Next Page: Electricity and the Electron
Also see: Circuit Diagrams

Circuit symbols are used in circuit diagrams which show how a circuit is connected together. The actual layout of the components is usually quite different from the circuit diagram.

To build a circuit you need a different diagram showing the layout of the parts on stripboard or printed circuit board.

Temporary and trial circuits are often built on breadboard which does not require soldering.

Wires and connections

 Component   Circuit Symbol  Function of Component
Wire wire symbol To pass current very easily from one part of a circuit to another.
Wires joined wires joined symbol A 'blob' should be drawn where wires are connected (joined), but it is sometimes omitted. Wires connected at 'crossroads' should be staggered slightly to form two T-junctions, as shown on the right.
Wires not joined wires crossing but not joined symbol In complex diagrams it is often necessary to draw wires crossing even though they are not connected. The simple crossing on the left is correct but may be misread as a join where the 'blob' has been forgotten. The bridge symbol on the right leaves no doubt!

Power Supplies

 Component   Circuit Symbol  Function of Component
Cell cell symbol Supplies electrical energy.
The larger terminal (on the left) is positive (+).
A single cell is often called a battery, but strictly a battery is two or more cells joined together.
Battery battery symbol Supplies electrical energy. A battery is more than one cell.
The larger terminal (on the left) is positive (+).
Solar Cell solar cell symbol Converts light to electrical energy.
The larger terminal (on the left) is positive (+).
DC supply DC power supply symbol Supplies electrical energy.
DC = Direct Current, always flowing in one direction.
AC supply AC power supply symbol Supplies electrical energy.
AC = Alternating Current, continually changing direction.
Fuse fuse symbol A safety device which will 'blow' (melt) if the current flowing through it exceeds a specified value.
Transformer transformer symbol Two coils of wire linked by an iron core. Transformers are used to step up (increase) and step down (decrease) AC voltages. Energy is transferred between the coils by the magnetic field in the core. There is no electrical connection between the coils.
Earth
(Ground)
earth symbol A connection to earth. For many electronic circuits this is the 0V (zero volts) of the power supply, but for mains electricity and some radio circuits it really means the earth. It is also known as ground.

Output Devices: Lamps, Heater, Motor, etc.

 Component   Circuit Symbol  Function of Component
Lamp (lighting) lamp (lighting) symbol A transducer which converts electrical energy to light. This symbol is used for a lamp providing illumination, for example a car headlamp or torch bulb.
Lamp (indicator) lamp (indicator) symbol A transducer which converts electrical energy to light. This symbol is used for a lamp which is an indicator, for example a warning light on a car dashboard.
Heater heater symbol A transducer which converts electrical energy to heat.
Motor motor symbol A transducer which converts electrical energy to kinetic energy (motion).
Bell bell symbol A transducer which converts electrical energy to sound.
Buzzer buzzer symbol A transducer which converts electrical energy to sound.
Inductor
(Coil, Solenoid)
inductor symbol A coil of wire which creates a magnetic field when current passes through it. It may have an iron core inside the coil. It can be used as a transducer converting electrical energy to mechanical energy by pulling on something.

Switches

 Component   Circuit Symbol  Function of Component
Push Switch
(push-to-make)
push-to-make switch symbol A push switch allows current to flow only when the button is pressed. This is the switch used to operate a doorbell.
Push-to-Break Switch push-to-break switch symbol This type of push switch is normally closed (on), it is open (off) only when the button is pressed.
On-Off Switch
(SPST)
SPST on-off switch symbol SPST = Single Pole, Single Throw.
An on-off switch allows current to flow only when it is in the closed (on) position.
2-way Switch
(SPDT)
SPDT switch symbol SPDT = Single Pole, Double Throw.
A 2-way changeover switch directs the flow of current to one of two routes according to its position. Some SPDT switches have a central off position and are described as 'on-off-on'.
Dual On-Off Switch
(DPST)
DPST switch symbol DPST = Double Pole, Single Throw.
A dual on-off switch which is often used to switch mains electricity because it can isolate both the live and neutral connections.
Reversing Switch
(DPDT)
DPDT switch symbol DPDT = Double Pole, Double Throw.
This switch can be wired up as a reversing switch for a motor. Some DPDT switches have a central off position.
Relay relay symbol An electrically operated switch, for example a 9V battery circuit connected to the coil can switch a 230V AC mains circuit.
NO = Normally Open, COM = Common, NC = Normally  Closed.

Resistors

 Component   Circuit Symbol  Function of Component
Resistor resistor symbol A resistor restricts the flow of current, for example to limit the current passing through an LED. A resistor is used with a capacitor in a timing circuit.
Some publications use the old resistor symbol:  old zig-zag resistor symbol
Variable Resistor
(Rheostat)
rheostat symbol This type of variable resistor with 2 contacts (a rheostat) is usually used to control current. Examples include: adjusting lamp brightness, adjusting motor speed, and adjusting the rate of flow of charge into a capacitor in a timing circuit.
Variable Resistor
(Potentiometer)
potentiometer symbol This type of variable resistor with 3 contacts (a potentiometer) is usually used to control voltage. It can be used like this as a transducer converting position (angle of the control spindle) to an electrical signal.
Variable Resistor
(Preset)
preset symbol This type of variable resistor (a preset) is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment. Presets are cheaper than normal variable resistors so they are often used in projects to reduce the cost.

Capacitors

 Component   Circuit Symbol  Function of Component
Capacitor capacitor symbol A capacitor stores electric charge. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but pass AC signals.
Capacitor, polarised polarised capacitor symbol A capacitor stores electric charge. This type must be connected the correct way round. A capacitor is used with a resistor in a timing circuit. It can also be used as a filter, to block DC signals but pass AC signals.
Variable Capacitor variable capacitor symbol A variable capacitor is used in a radio tuner.
Trimmer Capacitor trimmer capacitor symbol This type of variable capacitor (a trimmer) is operated with a small screwdriver or similar tool. It is designed to be set when the circuit is made and then left without further adjustment.

Diodes

 Component   Circuit Symbol  Function of Component
Diode diode symbol A device which only allows current to flow in one direction.
LED
Light Emitting Diode
LED symbol A transducer which converts electrical energy to light.
Zener Diode zener diode symbol A special diode which is used to maintain a fixed voltage across its terminals.
Photodiode photodiode symbol A light-sensitive diode.

Transistors

 Component   Circuit Symbol  Function of Component
Transistor NPN NPN transistor symbol A transistor amplifies current. It can be used with other components to make an amplifier or switching circuit.
Transistor PNP PNP transistor symbol A transistor amplifies current. It can be used with other components to make an amplifier or switching circuit.
Phototransistor Phototransistor symbol A light-sensitive transistor.

Audio and Radio Devices

 Component   Circuit Symbol  Function of Component
Microphone microphone symbol A transducer which converts sound to electrical energy.
Earphone earphone symbol A transducer which converts electrical energy to sound.
Loudspeaker loudspeaker symbol A transducer which converts electrical energy to sound.
Piezo Transducer piezo transducer symbol A transducer which converts electrical energy to sound.
Amplifier
(general symbol)
amplifier symbol An amplifier circuit with one input. Really it is a block diagram symbol because it represents a circuit rather than just one component.
Aerial
(Antenna)
aerial symbol A device which is designed to receive or transmit radio signals. It is also known as an antenna.

Meters and Oscilloscope

 Component   Circuit Symbol  Function of Component
Voltmeter voltmeter symbol A voltmeter is used to measure voltage.
The proper name for voltage is 'potential difference', but most people prefer to say voltage!
Ammeter ammeter symbol An ammeter is used to measure current.
Galvanometer galvanometer symbol A galvanometer is a very sensitive meter which is used to measure tiny currents, usually 1mA or less.
Ohmmeter ohmmeter symbol An ohmmeter is used to measure resistance. Most multimeters have an ohmmeter setting.
Oscilloscope oscilloscope symbol An oscilloscope is used to display the shape of electrical signals and it can be used to measure their voltage and time period.

Sensors (input devices)

 Component   Circuit Symbol  Function of Component
LDR LDR symbol A transducer which converts brightness (light) to resistance (an electrical property).
LDR = Light Dependent Resistor
Thermistor thermistor symbol A transducer which converts temperature (heat) to resistance (an electrical property).

Logic Gates

Logic gates process signals which represent true (1, high, +Vs, on) or false (0, low, 0V, off).
For more information please see the Logic Gates page.
There are two sets of symbols: traditional and IEC (International Electrotechnical Commission).
Gate Type Traditional Symbol IEC Symbol Function of Gate
NOT NOT gate traditional symbol NOT gate IEC symbol A NOT gate can only have one input. The 'o' on the output means 'not'. The output of a NOT gate is the inverse (opposite) of its input, so the output is true when the input is false. A NOT gate is also called an inverter.
AND AND gate traditional symbol AND gate IEC symbol An AND gate can have two or more inputs. The output of an AND gate is true when all its inputs are true.
NAND NAND gate traditional symbol NAND gate IEC symbol A NAND gate can have two or more inputs. The 'o' on the output means 'not' showing that it is a Not AND gate. The output of a NAND gate is true unless all its inputs are true.
OR OR gate traditional symbol OR gate IEC symbol An OR gate can have two or more inputs. The output of an OR gate is true when at least one of its inputs is true.
NOR NOR gate traditional symbol NOR gate IEC symbol A NOR gate can have two or more inputs. The 'o' on the output means 'not' showing that it is a Not OR gate. The output of a NOR gate is true when none of its inputs are true.
EX-OR EX-OR gate traditional symbol EX-OR gate IEC symbol An EX-OR gate can only have two inputs. The output of an EX-OR gate is true when its inputs are different (one true, one false).
EX-NOR EX-NOR gate traditional symbol EX-NOR gate IEC symbol An EX-NOR gate can only have two inputs. The 'o' on the output means 'not' showing that it is a Not EX-OR gate. The output of an EX-NOR gate is true when its inputs are the same (both true or both false).

Sets of circuit symbols to download

You can download complete sets of all the circuit symbols shown above. The sets are 'zipped' for convenience and they are provided in three formats:
  • WMF circuit symbols (32K) - Windows Metafiles.
    These vector drawings are the best format for printed documents on most computer systems, including Windows where they can be used in Word documents for example. They can be enlarged without loss of quality. If you are not sure which format is best for you I suggest you try this one first.

  • GIF circuit symbols (43K) - Graphics Interchange Format.
    These bitmap images are the best format for web pages but they print poorly and their bitmap nature will become obvious if they are enlarged. You can download individual symbols by saving the images used above on this page.

  • Drawfile circuit symbols (29K) - for RISC OS (Acorn) computers.
    These high quality vector drawings are suitable for almost all documents on a RISC OS computer. All the symbols were originally drawn in this format. They print perfectly and can be enlarged without loss of quality. Sorry, this format is NOT suitable for Windows computers.


Next Page: Electricity and the Electron | Studying Electronics
© John Hewes 2014, electronicsclub.info (based in the UK)
No part of this website may be reproduced in any way commercially without my prior permission.

Rapid

Hobbycraft
Site Map

Top of page

Home
Downloads
Books
FAQ
Contact
Discounts
Links

Construction
 - Breadboard
 - Stripboard
 - PCB

Soldering
 - Tools
 - Workbench

Components
 - Capacitors
 - Connectors
 - Diodes
 - ICs ('Chips')
 - CMOS logic ICs
 - 74 series ICs
 - Lamps
 - LEDs
 - Relays
 - Resistors
 - Switches
 - Transistors
 - Variable Resistors
 - Others
 - Starter Kit

555 Timer IC

Study
 - Block Diagrams
 - Circuit Diagrams
 - Circuit Symbols
 - Electricity/Electron
 - Series & Parallel
 - Voltage & Current
 - Meters
 - Multimeters
 - Resistance
 - Ohm's Law
 - Power & Energy
 - AC & DC Signals
 - Oscilloscopes
 - Power Supplies
 - Transducers
 - Voltage Dividers
 - Transistor Circuits
 - Analgoue & Digital
 - Logic Gates
 - Capacitance
 - Impedance
 - Counting
 - Quantities & Units
Projects
 - Dummy Alarm
 - Quiz
 - Traffic Light
 - Dice
 - Model Lighthouse
 - Simple Tester
 - Flashing LED
 - Electronic 'Lock'
 - Adjustable Timer
 - Light Alarm
 - Xmas Decoration
 - Railway Signal
 - Level Crossing
 - Lead Tester
 - 'Random' Flasher
 - Heart Badge
 - Valentine Heart

More Projects

Kits for Children

Electronics Club

Tsohost
Use coupon code
electron10 for 10%
discount off hosting
Privacy Policy & Cookies
This website does not collect any personal information unless you contact me by email. If you send me an email your name, email address, and any other personal information you supply will be used only to respond to your message. Your personal information will never be given to any third party without your permission.
This website displays affiliate advertisements. If you click on these advertisements the advertiser will know you came from this site and I may be rewarded if you become their customer. No personal information is passed to advertisers.
This website uses StatCounter cookies to estimate the number of unique visitors. No personal information is stored in the cookies. If you would like further information or wish to refuse these cookies please visit the StatCounter website.
To learn how to delete and control cookies from your browser please visit AboutCookies.org.