Electrical symbols and electronic circuit symbols are used for drawing schematic diagram.
The symbols represent electrical and electronic components.
| Symbol | Component name | Meaning |
|---|---|---|
| Wire Symbols | ||
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Electrical Wire | Conductor of electrical current |
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Connected Wires | Connected crossing |
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Not Connected Wires | Wires are not connected |
| Switch Symbols and Relay Symbols | ||
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SPST Toggle Switch | Disconnects current when open |
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SPDT Toggle Switch | Selects between two connections |
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Pushbutton Switch (N.O) | Momentary switch - normally open |
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Pushbutton Switch (N.C) | Momentary switch - normally closed |
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DIP Switch | DIP switch is used for onboard configuration |
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SPST Relay | Relay open / close connection by an electromagnet |
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SPDT Relay | |
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Jumper | Close connection by jumper insertion on pins. |
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Solder Bridge | Solder to close connection |
| Ground Symbols | ||
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Earth Ground | Used for zero potential reference and electrical shock protection. |
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Chassis Ground | Connected to the chassis of the circuit |
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Digital / Common Ground | |
| Resistor Symbols | ||
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Resistor (IEEE) | Resistor reduces the current flow. |
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Resistor (IEC) | |
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Potentiometer (IEEE) | Adjustable resistor - has 3 terminals. |
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Potentiometer (IEC) | |
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Variable Resistor / Rheostat (IEEE) | Adjustable resistor - has 2 terminals. |
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Variable Resistor / Rheostat (IEC) | |
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Trimmer Resistor | Preset resistor |
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Thermistor | Thermal resistor - change resistance when temperature changes |
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Photoresistor / Light dependent resistor (LDR) | Photo-resistor - change resistance with light intensity change |
| Capacitor Symbols | ||
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Capacitor | Capacitor is used to store electric charge. It acts as short circuit with AC and open circuit with DC. |
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Capacitor | |
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Polarized Capacitor | Electrolytic capacitor |
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Polarized Capacitor | Electrolytic capacitor |
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Variable Capacitor | Adjustable capacitance |
| Inductor / Coil Symbols | ||
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Inductor | Coil / solenoid that generates magnetic field |
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Iron Core Inductor | Includes iron |
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Variable Inductor | |
| Power Supply Symbols | ||
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Voltage Source | Generates constant voltage |
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Current Source | Generates constant current. |
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AC Voltage Source | AC voltage source |
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Generator | Electrical voltage is generated by mechanical rotation of the generator |
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Battery Cell | Generates constant voltage |
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Battery | Generates constant voltage |
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Controlled Voltage Source | Generates voltage as a function of voltage or current of other circuit element. |
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Controlled Current Source | Generates current as a function of voltage or current of other circuit element. |
| Meter Symbols | ||
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Voltmeter | Measures voltage. Has very high resistance. Connected in parallel. |
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Ammeter | Measures electric current. Has near zero resistance. Connected serially. |
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Ohmmeter | Measures resistance |
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Wattmeter | Measures electric power |
| Lamp / Light Bulb Symbols | ||
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Lamp / light bulb | Generates light when current flows through |
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Lamp / light bulb | |
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Lamp / light bulb | |
| Diode / LED Symbols | ||
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Diode | Diode allows current flow in one direction only - left (anode) to right (cathode). |
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Zener Diode | Allows current flow in one direction, but also can flow in the reverse direction when above breakdown voltage |
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Schottky Diode | Schottky diode is a diode with low voltage drop |
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Varactor / Varicap Diode | Variable capacitance diode |
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Tunnel Diode | |
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Light Emitting Diode (LED) | LED emits light when current flows through |
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Photodiode | Photodiode allows current flow when exposed to light |
| Transistor Symbols | ||
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NPN Bipolar Transistor | Allows current flow when high potential at base (middle) |
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PNP Bipolar Transistor | Allows current flow when low potential at base (middle) |
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Darlington Transistor | Made from 2 bipolar transistors. Has total gain of the product of each gain. |
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JFET-N Transistor | N-channel field effect transistor |
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JFET-P Transistor | P-channel field effect transistor |
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NMOS Transistor | N-channel MOSFET transistor |
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PMOS Transistor | P-channel MOSFET transistor |
| Misc. Symbols | ||
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Motor | Electric motor |
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Transformer | Change AC voltage from high to low or low to high. |
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Electric bell | Rings when activated |
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Buzzer | Produce buzzing sound |
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Fuse | The fuse disconnects when current above threshold. Used to protect circuit from high currents. |
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Fuse | |
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Bus | Contains several wires. Usually for data / address. |
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Bus | |
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Bus | |
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Optocoupler / Opto-isolator | Optocoupler isolates connection to other board |
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Loudspeaker | Converts electrical signal to sound waves |
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Microphone | Converts sound waves to electrical signal |
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Operational Amplifier | Amplify input signal |
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Schmitt Trigger | Operates with hysteresis to reduce noise. |
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Analog-to-digital converter (ADC) | Converts analog signal to digital numbers |
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Digital-to-Analog converter (DAC) | Converts digital numbers to analog signal |
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Crystal Oscillator | Used to generate precise frequency clock signal |
| ⎓ | Direct current | Direct current is generated from constant voltage level |
| Antenna Symbols | ||
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Antenna / aerial | Transmits & receives radio waves |
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Antenna / aerial | |
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Dipole Antenna | Two wires simple antenna |
| Logic Gates Symbols | ||
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NOT Gate (Inverter) | Outputs 1 when input is 0 |
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AND Gate | Outputs 1 when both inputs are 1. |
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NAND Gate | Outputs 0 when both inputs are 1. (NOT + AND) |
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OR Gate | Outputs 1 when any input is 1. |
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NOR Gate | Outputs 0 when any input is 1. (NOT + OR) |
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XOR Gate | Outputs 1 when inputs are different. (Exclusive OR) |
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D Flip-Flop | Stores one bit of data |
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Multiplexer / Mux 2 to 1 | Connects the output to selected input line. |
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Multiplexer / Mux 4 to 1 | |
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Demultiplexer / Demux 1 to 4 | Connects selected output to the input line. |
