What Are Electrolytic Capacitors and How Are They Used?

As a form of capacitor that is able to store much more electrical charge than other types, electrolytic capacitors are found in a number of common electrical circuits. The main feature of this type of capacitor is its use of an electrolyte, which is a liquid or gel that has a high concentration of charged particles or ions. By using these ions to store their electrical charge, electrolytic capacitors are able to hold a large amount of charge in a small space. This makes them especially useful for projects where space is limited, such as on aircraft. However, there are certain applications that they may be less suited for. Here, we will explain some key information about electrolytic capacitors in more detail, including some key characteristics to keep in mind so as to avoid potential malfunction.

How Are Electrolytic Capacitors Made?

Electrolytic capacitors can come in a number of different designs, but in general, they are produced by combining two conductive foils often made from aluminum, and a paper spacer that has been soaked in electrolytes. Additionally, electrolytic capacitors require both an anode (positive charged electrode) and a cathode (negatively charged electrode), so the anode is created by coating one of the conductive film layers with an oxide layer, and the other film layer is left uncoated to act as the cathode. The anode, soaked paper, and cathode are then stacked together and rolled into a cylindrical shape. With both the anode and cathode then connected to pins, they are finally ready to be attached to a circuit. Ultimately, this design is important for determining the capacitance of the device because factors such as the thickness of the electrolyte affect how much charge the capacitor will be able to hold.

Important Characteristics of Electrolytic Capacitors

Electrolytic capacitors are excellent devices for storing a great amount of charge within a small space, though using them the incorrect way can cause major issues. Here are some characteristics to pay attention to so you can avoid causing any damage to your device.

Firstly, electrolytic capacitors have a capacitance value that can typically drift as the capacitor gets older. While effective in certain applications, electrolytic capacitors generally have tolerance levels of around 20% which is why they are used in applications that do not require high precision. It should also be noted that the method in which electrolytic capacitors are made makes it so that the device is forward biased and polarized. This means that the voltage on the positive side always needs to be higher than the voltage on the negative side for the capacitor to function properly. If the polarity is ever reversed, then the capacitor will start to break down, damaging its internal components. Finally, since some electrolytes can be toxic or corrosive, care should always be taken when performing any work on electrolytic capacitors to make sure operators are safe. For this reason, a safety device is always fitted in the capacitor in the event of it overheating or short-circuiting, but extra precautions should be taken when conducting maintenance.

Where Are Electrolytic Capacitors Used?

Electrolytic capacitors are used for a wide array of applications and are found in a number of common electrical circuits. Generally, these capacitors are best for assemblies that require high capacitance values, but not high precision levels. As such, they are used in a variety of filtering applications to minimize the amount of voltage ripple like in audio amplification circuits where they can decrease the hum in a circuit. Electrolytic capacitors may also be employed as a low-pass filter in input and output smoothing if the signal is a DC signal with a faint AC component.


Electrolytic capacitors are one of the most common forms of capacitors which you can buy. Using an electrolyte to store extra charge, they are often employed in applications that require high charge storage capabilities in a limited space. If you are in need of electrolytic capacitors for your assembly, you can rely on ASAP Aviation Supplies with our inventory of more than 2 billion new, used, obsolete, and hard-to-find parts, including a large selection of high-quality capacitors. Many products in our inventory are subjected to rigorous quality assurance measures, tests, verifications, and assessments to ensure the quality of our items. To begin the purchasing process on any items of interest, simply submit a Request for Quote (RFQ) form from our website, and expect to receive a competitive quote for your comparisons in 15 minutes or less!


February 12, 2021

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