How to identify capacitors.

Capacitors are devices designed to store electrical charges. The amount of charge that a capacitor can store is called capacitance. Capacitors are basically made up of a dielectric material and a conductive material. Dielectric materials can be ceramic, paper, air, among others. The conductive material is usually aluminum. Both in sheets, the dielectric is always between the plates of conductive materials, where the electric field is formed. Dielectric is the insulating material that when subjected to a given electrical charge has its dielectric strength broken, and starts to behave as a conductor.

Capacitors have been used since the dawn of electronics, and since then they have undergone improvements and new models have emerged for different needs. There are several types of capacitors, such as ceramic, electrolytic capacitors, tantalum capacitors, adjustable capacitors, SMD capacitors, etc. Capacitors are used in electronic circuits, voltage sources, sensors, oscillators, among other places and functions. It is very easy to find it in some electronics, but it is often difficult to read the specifications of the capacitor.

Capacitors are simple devices to handle, the greatest care when talking about capacitors is always their polarization. It is very important to polarize it in the correct way (larger terminal on the positive, smaller terminal on the negative), because if it is polarized in the wrong way this device can explode and be obviously damaged. A point that usually brings doubts to those who use the capacitor, or to those who do not know the device, are the numbers described on the surface of this device. Now see some parameters covered in the capacitors:


It is the amount of charge that the capacitor is capable of storing, measured in Farad (F). In the capacitor description, this parameter is specified with submultiples, for example, µF, nF, or pF.

Some capacitors specifically name capacitance, such as ceramic capacitors. In whole numbers (100, 300, etc.) it has the unit of measurement in pF, and in decimal numbers (0.1; 0.40; etc.).

Working voltage

Ideal or maximum voltage for the capacitor to perform its function in the circuit without complications or risks to the process. Expressed in volts (V) or kilovolts (kV).


Due to the capacitive characteristics of the capacitor, the nominal values ​​can work in a negative and positive, expressed and percentage variation. For example, a 10 µF capacitor with 10% tolerance can have values ​​of 11 µF and 9 µF.

It is not common to use a color table for capacitor specifications (only in old models), as is done with resistors. The table below is an encoding used by manufacturers. She uses numbers instead of colors to indicate each character. This table is used for capacitors with 5 characters, where the first three refer to the capacitance value, the fourth to tolerance and the fifth to working voltage.

Table for reading capacitors.

This makes it much easier to read and interpret the data described on the capacitors, to use them correctly and for the situation to which it is specified.

Capacitor types

As stated earlier, what differentiates one capacitor from another is the dielectric material used in each one. Ceramic capacitors, for example, have dielectric material, ceramic, and so on. Visually we can also identify different capacitors, taking into account that each one has a different design. In order to identify whether a capacitor is in good working condition, tests are carried out with devices, such as multimeters.