A polarized capacitor installed in the wrong direction (inversion of positive and negative poles) can put your assembly at risk. Apart from the fact that it won't work, it could cause irreparable damage to the assembly in general, and to sensitive components such as integrated circuits in particular.

Capacitor Overview

A capacitor is a passive electronic device that stores an electrical charge. It is made up of two electrical conductors, or "armatures", very close together, but separated by an insulator, or "dielectric".

It is used for:

• stabilizing a power supply (discharging during voltage drops and charging during voltage peaks);
• initialize the state of logic signals on power-up;
• filter interference at the terminals of integrated circuits;
• separate alternating current from direct current, the latter being blocked by the capacitor;
• energy storage (supercapacitor).

Different Capacitor Technologies

Depending on their role and use, some technologies are more appropriate than others.

You'll find:

Service voltage

Each capacitor is characterized by its operating voltage, i.e. the maximum electric field it can withstand. This field, known as the disruptive field, is the limit beyond which a spark shoots out between the two armatures, causing the capacitor to discharge (like lightning in a thunderstorm), generally accompanied by its destruction: capacitor breakdown !

The polarized capacitors used on this website

You will find below the different types and technologies of polarized capacitors used in the assemblies proposed on this site:

A polarized capacitor always shows an indication of its polarities. This indication varies according to model and manufacturer. Depending on the case, the indicator will show either the negative or positive pin:

• Electrolytic capacitors: it's easy to distinguish the poles. In general, the negative pin is indicated by a colored stripe running the length of the capacitor, indicating the negative pole ("-" sign). In addition, the negative pin is always shorter. In the case of an axial electrolytic capacitor, the positive side is additionally marked by a notch all around the case.
• SMD tantalum or ceramic capacitor: the positive pin is always marked by a line or a bevel in the component (or both).
• Polymer capacitor: the negative pin is indicated by a dark arc on the top of the case. The color of the arc may vary according to manufacturer and capacitor range (black, red, blue, violet...).

Unit of measurement for capacitor capacity

Capacitance is measured in Farad (F). This unit, too large for our assemblies, is broken down into :

Know how to read the value of a polymer capacitor

Each manufacturer has adopted its own rule for coding the characteristics of a capacitor. The two items of information of particular interest to us are:

• the capacitance of the capacitor (generally µF for a polarized capacitor);
• the maximum voltage that must not be exceeded to avoid damaging the component.

The value of capacity

In general, the capacitance value is always clearly marked on the component, but it should not be confused with the manufacturer's code. Knowing the standardized capacitor values will make it easier to distinguish the capacitance number from the batch number. Capacitance values are standardized in different series. The most common, the E12 series, offers the following values:

Examples:

• The value 1.0 authorizes capacitance values ​​whose first digit is "1" : 1µF, 10µF, 100µF, 1000µF ;
• The value 2.7 authorizes capacitance values ​​whose first two digits are "27" : 2.7µF, 27µF, 270µF or 2700µF ;
• etc...

Without clear marking of the unit of measurement, it is generally microfarad (µF).

The maximum voltage

Depending on the manufacturer, the voltage may be written in plain text or in code. Here's a list of the different standardized voltages and the associated code:

Examples

Some examples of how to read the information available on the top of a polymer capacitor, according to different manufacturers: