Common Symbols in Electrical Circuit Diagrams

Common Symbols in Electrical Circuit Diagrams

Resistor Symbols

• Standard Resistor: A zigzag line or rectangle.
• Variable Resistor: A zigzag line with an arrow across it.
• Fixed Resistor: A rectangle with leads extending from each side.

Inductor Symbols

• Standard Inductor: A coiled line or series of loops.
• Variable Inductor: A coiled line with a dashed line or an arrow indicating variability.

Ground Symbols

• Earth Ground: Three horizontal lines, the top line shorter than the bottom.
• Chassis Ground: A series of lines that descend in size, often depicted with a triangle.

Capacitor Symbols

• Standard Capacitor: Two parallel lines (plates) with a gap between them.
• Polarized Capacitor: Similar to a standard capacitor but one plate is curved to indicate polarity.

Battery Symbols

• Single Cell Battery: A series of alternating long and short lines (long line positive, short line negative).
• Multiple Cells Battery: Multiple sets of the single cell symbol placed in series.

Resistor Symbols

• Standard Resistor: Represented as a zigzag line or rectangle, indicating a component that resists electric current.
• Variable Resistor: Depicted as a zigzag line with an arrow, allowing for adjustable resistance in a circuit.
• Fixed Resistor: Illustrated as a rectangle with leads extending from either side, signifying a resistor with constant resistance.

Inductor Symbols

• Standard Inductor: Shown as a coiled line or a series of loops, symbolizing a component that stores energy in a magnetic field when electrical current flows through it.
• Variable Inductor: Illustrated with a coiled line and either a dashed line or an arrow, indicating the ability to change inductance.

Ground Symbols

• Earth Ground: Represented with three horizontal lines, where the top line is shorter than the bottom, indicating a reference point in the electrical circuit for safety and stability.
• Chassis Ground: Depicted as a series of descending lines, often in a triangular shape, denoting a common ground reference for the metal enclosure of a device.

Capacitor Symbols

• Standard Capacitor: Illustrated as two parallel lines (plates) separated by a gap, representing a device that stores electrical energy in an electric field.
• Polarized Capacitor: Similar to a standard capacitor but with one curved plate to indicate the correct polarity for connection.

Battery Symbols

• Single Cell Battery: Visualized as alternating long and short lines, with the long line representing the positive terminal and the short line the negative terminal.
• Multiple Cells Battery: Consists of multiple sets of the single cell symbol connected in series, indicating the cumulative voltage output from several cells linked together.

Resistor Symbols

• Standard Resistor: Represented by a zigzag line or rectangle, indicating resistance in the circuit.
• Variable Resistor: Displays a similar shape to a standard resistor but includes an arrow which indicates it can be adjusted.
• Fixed Resistor: Often shown as a rectangular box, indicating a constant resistance value.
• Mismatched Resistor: Appears with a dotted line or special notation, used to indicate a specific functionality or type.

Diode Symbols

• Standard Diode: Illustrated by a triangle pointing to a line, representing the direction of current flow from anode to cathode.
• Zener Diode: Same as a standard diode but adds a bent line at the cathode, indicating its function in voltage regulation.
• Light Emitting Diode (LED): Depicted as a standard diode symbol with two arrows pointing outward, representing emitted light.

Power Source Symbols

• Battery: Illustrated by a series of long and short parallel lines, each representing a cell in the battery.
• Single Cell: Represented by one pair of long and short lines, indicating a single electrochemical cell.
• DC Power Supply: Shown as a circle with plus (+) and minus (-) signs, denoting direct current with specific polarity.
• AC Power Supply: Represented by a sine wave symbol or a circle containing a wave, illustrating alternating current.

Transistor Symbols

• NPN Transistor: Illustrated as a circle with three leads, with the arrow pointing outward from the emitter, indicating current flow direction.
• PNP Transistor: Similar to the NPN but the arrow points inward toward the emitter, signifying a different current flow direction.
• Field-Effect Transistor (FET): Depicted with variations based on gate types, typically includes representations of gate, drain, and source connections.

Capacitor Symbols

• Standard Capacitor: Shown as two parallel lines (plates) with a space in between, indicating energy storage. One line may be curved for polarized capacitors.
• Electrolytic Capacitor: Similar to the standard symbol, but marked with a plus sign on one plate to show polarity.
• Variable Capacitor: Similar to a standard capacitor but includes an adjustment mechanism, often represented with a line or gap beside the plates.