Electrolytic Capacitor: A Key Component in Electronic Circuits

by Yuvi K - December 24, 2023

What is an Electrolytic Capacitor?

An electrolytic capacitor (इलेक्ट्रोलिटिक कैपेसिटर) is a type of capacitor that is used in electronic circuits to store electrical energy and provide short-term electrical power. It consists of two metal foils wrapped in a dielectric material, which is usually a combination of an ion-conducting fluid and a non-conducting polymer. The metal foils are connected to the two electrical terminals, and when voltage is applied across the the terminals, an electric current is induced that flows through the dielectric material, charging the capacitor.

Uses and Benefits of Electrolytic Capacitors

Electrolytic capacitors are widely used in a variety of electronic circuits and devices such as power supplies, digital audio systems, amplifiers, and RF communication circuits. They offer a number of important benefits such as:

High capacitance – Electrolytic capacitors are available in capacitance values ranging from 1 μF up to 470 μF, making them ideal for use in circuits where high capacitance is needed.
High-Ripple Currents – Electrolytic capacitors are capable of handling high ripple currents, making them suitable for use in power supplies.
Low Impedance – Electrolytic capacitors have very low impedance when compared to other types of capacitors, making them ideal for use in applications where high frequency signals must be filtered.
Low Cost – Electrolytic capacitors are relatively inexpensive, making them a cost-effective solution for many applications.

Working of Electrolytic Capacitor

When a voltage is applied across the two terminals of an electrolytic capacitor, a current is induced which flows through the dielectric material. This current polarizes the electrodes in the capacitor, resulting in the accumulation of electrons on one electrode, and the depletion of electrons on the other. This separation of charge creates an electric field which stores the electrical energy in the capacitor.

The current induced by the applied voltage continues to charge the capacitor until the voltage reaches a certain level. At this point, the current flow stops and the charge begins to dissipate as the field begins to collapse. As the voltage is reduced, the charge on the electrodes of the capacitor gradually decreases, and the stored energy is released.

Types and Working of Electrolytic Capacitors

There are two primary types of electrolytic capacitors: aluminum and tantalum. Both types are polarized and consist of two metal foils, but the dielectric material used in each type is different.

Aluminum Electrolytic Capacitors

Aluminum electrolytic capacitors employ an aluminum foil connected to a liquid electrolyte to form the dielectric material. When voltage is applied across the electrodes, electric current passes through the liquid, causing the positively charged ions to form a “double layer” on the surface of the aluminum. This double layer accumulates and store electrical energy, creating a potential difference between the two electrodes.

Tantalum Electrolytic Capacitors

Tantalum electrolytic capacitors employ a tantalum foil combined with a solid manganese dioxide electrolyte, which creates a very thin dielectric layer on the surface of the foil. When voltage is applied across the electrodes, electrons are forced into the surface of the tantalum, giving it a negative charge and allowing it to store electrical energy.

Advantages, Disadvantages and Applications of Electrolytic Capacitors

Advantages

High capacitance values
Low leakage current
Good tolerance
Low cost

Disadvantages

Require a voltage to be applied, otherwise they may fail to charge
Less stable than ceramic capacitors
Limited to relatively low ripple currents
Voltage rating decreases with increasing capacitance

Applications

Electrolytic capacitors are used in a variety of applications, such as power supplies, digital audio systems, amplifiers, and RF communication circuits, among others. They are especially popular in switched-mode power supplies due to their ability to handle high ripple currents.

Conclusion

In conclusion, electrolytic capacitors are an important component in many types of electronic circuits and devices. They offer high capacitance values, low leakage current, and good tolerance, making them well-suited for many applications. Furthermore, they are relatively inexpensive and easy to obtain, making them a cost-effective and readily available solution.