Basics of Capacitor: Capacitor Symbols (2024)

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A capacitor's main purpose is to store charge. Electrons build up on one plate of a capacitor when it is linked to a power source, while an opposite but equal charge builds up on the other plate.

Basic Concepts of Capacitors

An electrical energy source that is passively stored in an electric field is called a capacitor. It is made up of two conducting plates and a dielectric, which is an insulating substance. An electric field forms across the dielectric when a voltage is applied between the plates, which causes an electrical charge to build up.

Figure 1: Capacitor

Main purpose of types of capacitors is to store charge. Electrons build up on one plate of a capacitor when it is linked to a power source, while an opposite but equal charge builds up on the other plate. The surface area, spacing, and kind of dielectric material all affect how much charge a capacitor can hold. The unit of measurement for this is farads (F).

Types of Capacitors You should know

Type of Capacitor	Subcategories	Description
Ceramic Capacitors	Class 1: NP0, C0G Capacitor	Very stable, minimal change in capacitance with temperature. Used in timing and precision applications.
	Class 2: X7R Capacitor	Good stability, suitable for bypass and decoupling applications over a wider temperature range.
	Class 2: Y5V Capacitor	High capacitance value, significant capacitance change with temperature. Used where size and cost are critical.
	Class 2: Z5U Capacitor	Used for bypass and decoupling; not suitable where tight capacitance tolerance is needed.
Electrolytic Capacitors	Aluminum Electrolytic	High capacitance, polarized. Ideal for power supply filters and audio amplifiers.
	Tantalum Electrolytic	Higher stability and reliability than aluminum, polarized. Used in medical and military applications.
	Niobium Electrolytic	Similar to tantalum, cost-effective, and used in various electronic applications.
Film Capacitors	Polyester Film (Mylar)	Good dielectric strength, used in coupling and decoupling applications.
	Polypropylene Film (PP)	Excellent electrical properties, used in high-frequency and power applications.
	Polystyrene Film (PS)	Low cost, high stability, used in filters and timing circuits.
	Polyethylene Naphthalate (PEN)	High temperature and frequency performance, suitable for demanding environments.
Super Capacitors	Double-layer (EDLC)	Used for rapid charge and discharge cycles such as in-memory backup systems.
Super Capacitors	Pseudo Capacitors	Combines capacitor-like and battery-like properties for energy storage and high-power applications.
Variable Capacitors	Air Variable	Manually adjustable, used in radio tuning and frequency adjustment.
	Trimmer Capacitors	Small, variable capacitors for device tuning during manufacturing or in-field adjustments.
	Vacuum Variable	High voltage, stable tuning applications, used in high power and radio frequency systems.

A Guide to Capacitor Symbols

Image	Capacitor symbol	Type of Capacitor
	Figure 2: Bipolar Capacitor Symbol	Bipolar Capacitor
	Figure 3: Butterfly Capacitor Symbol	Butterfly Capacitor
	Figure 4: Differential Capacitor Symbol	Differential Capacitor
	Figure 5: Feed through Capacitor Symbol	Feed through Capacitor
	Figure 6: Generic Capacitor Symbol	Generic Capacitor
	Figure 7: Polarized Electrolytic Capacitor Symbol	Polarized Electrolytic Capacitor
	Figure 8: Split Stator Capacitor Symbol	Split Stator Capacitor
	Figure 9: Trimmer Capacitor Symbol	Trimmer Capacitor
	Figure 10: Variable Capacitor Symbol	Variable Capacitor

Video Related to Capacitor Symbols

Some Common Capacitor Symbols You Should Know

Image	Capacitor symbol	Type	Description
	Figure 11: Disc ceramic Capacitor Symbol	Disc ceramic Capacitor	Disc ceramic capacitors are widely used in electronic circuits. On both sides of the ceramic discs are metal electrodes. Disc ceramic capacitors have a stable and reliable dielectric, which makes them adaptable.
	Figure 12: Multilayer Ceramic Capacitor Symbol	Multilayer Ceramic Capacitor (MLCC)	Metal electrodes are placed on opposite sides of ceramic layers in multilayer ceramic capacitors, or MLCCs. Ceramic layers are stacked as dielectrics to get the desired capacitance.
	Figure 13: Metalized Film Capacitor Symbol	Metalized Film Capacitor	Metalized film capacitors use a thin plastic film as the electrode and one or both sides coated in metal as the dielectric. Aluminum or zinc is deposited onto the plastic sheet through metalization.
	Figure 14: Mica Capacitor Symbol	Mica Capacitor	Thin mica sheets with metal electrodes on either side are known as mica capacitors. They are low-loss and stable for high-frequency applications. Mica capacitors are needed in RF, filter, and high-precision timing circuits.
	Figure 15: Aluminum Electrolytic Capacitor Symbol	Aluminum Electrolytic Capacitor	Aluminum oxide is used as a dielectric in aluminum electrolytic capacitors. They are widely used in electrical circuits due to their inexpensive cost, high voltage, and high capacitance.
	Figure 16: Tantalum Electrolytic capacitor symbol	Tantalum Electrolytic capacitor	Tantalum electrodes are used in tantalum electrolytic capacitors. These capacitors are widely used in electrical circuits due to their high capacitance density, stability, and dependability.
	Figure 17: Niobium Electrolytic Capacitor Symbol	Niobium Electrolytic Capacitor	Niobium oxide dielectrics are found in niobium electrolytic capacitors. They need to be connected correctly since they are polarized similarly to tantalum electrolytic capacitors.
	Figure 18: Aluminum Polymer Capacitor Symbol	Aluminum Polymer Capacitor	Conductive polymers are used in aluminum polymer capacitors in place of liquid or gel electrolytes. They are more dependable, stable, and age- and temperature-resistant.
	Figure 19: Variable Vacuum Capacitor Symbol	Variable Vacuum Capacitor	Two conducting plates that are vacuum-separated make vacuum capacitors. These capacitors are appropriate for high-power RF circuits in transmitters, transceivers, and amplifiers because of their high voltage rating and capacitance density.
	Figure 20: Variable Air Gap Capacitor Symbol	Variable Air Gap Capacitor	A little air gap divides the two conducting plates of an air gap capacitor. They are used in high-frequency, high-voltage applications where other capacitors would not function.
	Figure 21: Ceramic Trimmer Capacitor Symbol	Ceramic Trimmer Capacitor	Ceramic trimmer capacitors adjust the capacitance in a circuit. They have two conductive plates with one on a moveable arm to change the capacitance value and the other two separated by a ceramic dielectric material.
	Figure 22: Film Trimmer Capacitor Symbol	Film Trimmer Capacitor	Another variable capacitor used to adjust circuit capacitance is the film trimmer capacitor. They have two conductive plates with one on a moveable arm to change the capacitance value and the other two separated by a thin layer of dielectric substance.
	Figure 23: Supercapacitor Symbol	Supercapacitor	Supercapacitors can display both positive and negative polarity indicators. Supercapacitors are used in electronics, electric vehicles, and renewable energy systems to provide high power and fast charge/discharge cycles.
	Figure 24: Motor Run and Start Capacitor Symbol	Motor Run and Start Capacitor	The choice and installation of the motor run and start capacitor determine performance and dependability. Take into account the capacitance, voltage, and other features when selecting a capacitor for a motor application.

CapacitorSymbol Naming Rules

Primary name (letter)		Material (letter)		Type (numeric or alphabetic)					Serial number (number)
Symbol	Meaning	Symbol	Meaning	Symbol	Meaning
Symbol	Meaning	Symbol	Meaning	Symbol	Ceramic Capacitor	Mica Capacitors	Organic capacitor	Electrolytic Capacitors
C	Capacitor	A	Tantalum electrolytic	1	Round	Non-sealed	Non-sealed	Foil	Use numbers to indicate the serial number to distinguish the capacitor's external dimensions and performance indicators.
		B	Non-polar organic films such as polystyrene	2	Tube	Non-sealed	Non-sealed	Foil
		C	High-frequency ceramic dielectric	3	Stacked	Seal	Seal	Sintered Powder, Non-Solid
		D	Aluminum electrolysis	4	Monolith	Seal	Seal	Sintered Powder, Solid
		E	Electrolysis of other materials	5	Piercing		Piercing
		G	Alloy electrolysis	6	Pillar, etc.
		H	Composite dielectric	7				Unpolarized
		I	Vitreous enamel	8	High Pressure	High Pressure	High Pressure
		J	Metalized paper media	9				Specialty
		L	Polyester and other polar organic films	G	High Power Type
		N	Niobium electrolytic	T	Stacked Chip Type
		O	Glass film	W	Trimmer Type
		Q	Lacquer film	J	Metallized Type
		T	Low-frequency porcelain	Y	High Voltage Type
		V	Mica paper
		Y	Mica
		Z	Paper

Different Standards for Capacitor Symbols

Standard	Region/Country	Non-Polarized Capacitors Description	Polarized Capacitors Description	Visual Notes/Identifiers
IEC	International	Two straight, parallel lines	One straight line and one curved line, indicate polarity	Simple and uniform lines; widely recognized in Europe
ANSI	United States	Two straight, parallel lines	Lines can be straight or curved with a plus (+) sign on the positive side	Clear polarity indication, common in the US
JIS	Japan	Two straight, parallel lines	Often marked with polarity, using straight or slightly modified lines	Polarity is often more explicitly marked than in IEC/ANSI
GOST	Russia	Similar to IEC but may include slight variations	Explicit polarity markings, possibly using different symbols	Unique elements that cater to Russian engineering standards
GB	China	Two straight, parallel lines, closely following IEC	Slight variations from the IEC style, with clear polarity indications	Adaptations may reflect specific Chinese documentation practices

Basic Concepts of Multimeter

Feature	Description	Details and Examples
Type	Analog vs. Digital Multimeters	Analog uses a needle; Digital uses an LCD.
Measurements	Voltage, Current, Resistance, and Continuity	Voltage: AC/DC; Current: AC/DC; Resistance measured in ohms; Continuity with audible beep.
Additional Functions	Capacitance, Frequency, Temperature, Duty Cycle, Diode Test	Capacitance in farads; Frequency for electronic troubleshooting; Temperature with a probe.
Probes and Leads	Types of probes and their uses	Standard pointed probes for direct contact; Alligator clips for clipping to components and wires.
Safety Features	Protects both the user and the multimeter	Input protection against overvoltage, fused leads to prevent overload, CAT ratings ensure appropriate use in different electrical environments.
Usage	Proper setting and interpretation	Always select the correct measurement type and range; Read digital display or analog scale accurately. Avoid parallax errors in analog meters.
Maintenance	Ensuring long-term accuracy and safety	Regular calibration, especially after a drop or significant event; Inspection of leads and probes for wear or damage.
Common Ranges	Typical measurement ranges available on most multimeters	Voltage up to 600V; Current up to 10A; Resistance up to 40MΩ.
Input Impedance	Affects the measurement accuracy, especially in high-resistance circuits	Typically 10 MΩ in digital multimeters, which is suitable for most applications.
Accuracy	The precision of measurements, usually a percentage of the reading	Digital multimeters typically offer accuracy better than 1% for most measurements.

How to use a multimeter to measure capacitors

Step	Description	Details & Tips
1. Safety First	Discharge the capacitor.	Avoid shocks by ensuring the capacitor is fully discharged.
2. Set Multimeter	Select the capacitance measurement mode (Cap mode).	Use auto-ranging if available, otherwise, select a manual range close to the expected capacitance.
3. Connect Probes	Attach the probes to the capacitor terminals.	Red to positive, black to negative; for non-polarized capacitors, the connection direction doesn't matter.
4. Read Value	Observe the display for the capacitance reading.	Wait until the reading stabilizes; values are usually in pF, nF, or μF.
5. Check Accuracy	Compare the reading with the capacitor's labeled value.	Consider tolerance; significant discrepancies might indicate a faulty capacitor.
6. Troubleshoot	Address any issues if readings are inconsistent or out of range.	Ensure full discharge, firm probe contact, and correct multimeter settings.
7. Disconnect	Safely remove probes and turn off the multimeter.	Always store your tools properly to avoid damage.

How to Create Capacitor Symbol in Altium

1. Open Altium Designer

Launch the software and open a new or existing project.

2. Create Schematic Library

Navigate: File > New > Library > Schematic Library.

This opens a new schematic library tab.

3. Create a New Component

In the schematic library tab, right-click in the Components list and select New Component.

Enter the name of your component, e.g., "Capacitor".

4. Draw the Capacitor Symbol

Select Place > Line from the top menu to draw the capacitor plates.

Draw two parallel lines for a non-polarized capacitor. For a polarized capacitor, vary the line lengths.

5. Add Pins

Select Place > Pin.

Click at the ends of each line to place pins. These represent the electrical connections.

6. Configure Pins

Double-click each pin to open the pin properties dialog.

Set properties such as pin name and electrical type (e.g., Passive, Electrical).

7. Define Component Properties

With the symbol selected, fill out the Properties panel with details like designator (e.g., C?), description, etc.

8. Save the Schematic Library

Click File > Save As to save your library with an appropriate name in a designated location.

9. Compile and Add Library to the Project

Right-click the library in the Projects panel and select Compile Library.

Add the library to your project: Project > Add Existing to Project.

10. Place the Capacitor in a Schematic

Open a schematic sheet, then Place > Component, and select the capacitor from your library.

Click to place the capacitor in the schematic.

FAQs About Capacitor Symbol

What is a capacitor symbol?

A capacitor is represented graphically in electronic schematics by the symbol "capacitor," which is usually two parallel lines. To show polarity, polarized capacitors may have one straight line and one curved line.

In Altium Designer, how can I make a symbol for a capacitor?

In Altium Designer, to build a symbol for a capacitor, open a new schematic library, make a new component, draw the capacitor plates using the 'Place Line' tool, add pins, adjust properties, save the library, compile it, and add it to your project so that it can be used in schematics.

What distinguishes the symbols for polarized and non-polarized capacitors?

Two parallel lines are used to symbolize non-polarized capacitors. Similar to electrolytes, polarized capacitors are shown with a single curved line representing the negative terminal and a single straight line representing the positive terminal.

Is it possible to change an existing Altium Designer capacitor symbol?

Yes, you can alter an already-existing symbol by choosing it, making the required adjustments, and saving the modifications after opening the schematic library where it is kept. Recompile the library after making any changes.

Why do certain schematic diagram symbols for capacitors have different shapes?

Different capacitor kinds (such as ceramic, electrolytic, and tantalum), each with special characteristics and applications in circuits, are frequently indicated by different shapes or changes in the symbols. The changes to the symbols aid in quickly distinguishing between various kinds.

How can I make sure the industry criteria for my capacitor symbol are met?

When creating your symbols, consult industry standard documents such as IEEE or IEC rules. Maintaining compliance with these standards contributes to the readability and compatibility of many platforms and teams.

After inserting my capacitor symbol into a diagram, what should I do if it is not visible?

Verify that the library was added to the project and compiled correctly. In your schematic, double-check that the layer and visibility settings aren't obscuring the symbol.