Passive Component Circuit Symbols

- circuit symbols or circuit diagram symbols for passive components including capacitors, resistors, and inductors.

There are many different circuit symbols for passive components.

This page provides circuit symbols for passive components including resistors, capacitors, inductors and transformers.

As these circuit diagram symbols for some passive components, particularly resistors vary according to the geographical location where they were generated, those for US and European commonly used versions are given where possible.

The circuit symbols are based on those that appear to be most widely used.

Resistor circuit diagram symbols

The selection of resistor circuit diagram symbols:

The standard resistor symbol used within Europe based on the rectangle shape
Resistor (Europe)

The standard European resistor symbol showing the resistor element as a rectangular shape and the slider as an arrow entering the long side of the rectangle
Potentiometer (Europe)

The circuit symbol for the varibale resistor showing an arrow across the rectangle
Variable resistor (Europe)

The US standard for a resistor schematic symbol showing the jagged line indicating the resistance in the wire
Resistor (US)

US standard schematic circuit symbol for a potentiometer
Potentiometer (US)

The US standard circuit schematic symbol for a variable resistor
Variable resistor (US)

The circuit schematic symbol for a light dependent resistor. The arrows indicate the incoming light.
Light dependent resistor, LDR

The circuit schematic symbol for a light dependent resistor
Thermistor (temperature dependent resistor)

Capacitor circuit diagram symbols

The selection of capacitor schematic symbols:

The schematic symbol for a non-polar capacitor showingt he two parallel solid lines depicting the parallel plates of the component.
Capacitor (Fixed non-polar)

The schematic symbol for a variavble capcitor showing an arrow across the plates to indicate it is variable
Variable capacitor (Operator adjustable)

Schematic symbol for a preset capacitor with a flat headed arrow across the plates of the capacitor.
Variable capacitor (Preset)

Polarised capacitor schematic symbol as used in Europe. This shows the positive plate non-solid and a + mark by its side to indicate the polarity
Capacitor (Fixed polar Europe)

The schematic symbol typically used withn the USA to indicate a polarised capacitor such as an electrolytic. Here the negative plate is indicated by the curved line.
Capacitor (Fixed polar US)

Inductor circuit diagram symbols

The selection of inductor schematic symbols:

Schematic symbol for a basic air cored indctor - symbol shows the coil only and no core.

Schematic symbol for a ferrite cored inductor - the symbol shows the coil and the dotted lines represent the ferrite core
Inductor with ferrite core

Iron cored inductor symbol - the coil is shown as the looped wire and the iron core as the solid lines.
Inductor with laminated / iron core

Schematic symbol for an indiuctor with a tap.
Inductor with tap on the coil
(Note: the position of the tap can be moved to indicate approximately where on the coil the tap is positioned).

Transformer circuit diagram symbols

The selection of transformer schematic symbols:

Schematic symbol for a basic air cored transfomer - it can be seen that there are no lines alongside the coil and this indicates it is air cored.
Transformer with air core
(Note: turns on either side of the transformer may be alterd to indicate step up or step down).

Schematic symbol for a ferrite cored transformer - the dotted lines alongside the coils indicate the presence of a ferrite core.
Transformer with ferrite core

Symbol for an iron cored transfomer - the solid lines between the two coils indicate a laminated iron core
Transformer with laminated or iron core

Schematic symbol for a transformer with a centre tap - often the tap is positioned to give a very broad indication of the measure of the turns ration in each section.
Transformer with centre tap

Schematic symbol indicating a transformer with a variable core such as those used in radio intermediate frequency amplifiers where the core is adjusted for tuning.
Transformer with adjustable core
(Typically used for tuning, e.g. as in IF transformers, etc).

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