A capacitor, which makes proper uses of another electrolyte to achieve more capacitance than the other form of capacitor, is known as an electrolytic capacitor. It is a liquid substance with a highly influential mixture of anion subatomic particles. Usually, three various types of capacitors are termed as an electrolytic capacitor. They are as follows
Aluminium electrolytic capacitor
Tantalum electrolytic capacitor
Niobium electrolytic capacitor
A particular type of electrolytic capacitor with the capacity to store hundreds and thousands of farads more electric charge is called supercapacitors. They are often familiar as a double-layer electrolytic capacitor.
Electrolytic Capacitor Uses
All the capacitors under the electrolytic capacitor are neutralized. That is, the voltage of anode is always higher than that of the cathode. Due to the capability of massive electric charge storage, they are mostly employed to deliver low-pass signals. In electrical supply, they are profoundly implemented for noise filtering or decoupling.
Sometimes they are used in input and output smoothing. They are employed as a low-frequency filter if the signal is a DC one with a feeble AC constituent.
Electrolytic capacitors are mostly found working as filters in loud-speakers. It aims to decrease the amplifier’s vibration. The vibration of the prime one is a 50Hz 60 Hz electrical sound persuaded from the mains supply. It could be heard if expanded.
Features of Electrolytic Capacitor
Let's discuss some features of the electrolytic capacitor:
Accumulation of Capacitance
The electrical features of it depend mostly on the involved electrolyte and the anode. The ability to store an electric charge of the electrolytic capacitors, have huge forbearances 20% and accumulates at the minimum rate as the time goes on. An aluminium capacitor is implemented for this. Whose very little capacitance is 47µF can be anticipated to have a value of something between 37.6µF to 56.4µF.
Tantalum capacitors are also able to tolerate high, but their maximum working voltage is at the bottom. So they can't work as a substitute for aluminium capacitors.
Electric Charge Storage Capacity, Worth, and Forbearances
The electrolyte and anode are mostly defined as the electrical features of a device. The results and the capacity to store electric charges are dependent on temperature and frequency. The capacitor with non-solid electrolytes contents shows a tremendous capacity over temperature and frequency than the solid electrolytes content capacitor. The basic measuring unit of the electric storage ability of an electrolyte capacitor is microfarad. The value of capacitance, which is mentioned by the producers in the datasheets, is known as nominal capacitance or rated capacitance. If the value of a device's electrical storage capacity is measured at 1kHz frequency, it will be a 10 per cent deduction of 100/110Hz. The temperature there will be 200 c.
The capacity tolerance can be defined as the percentage of the permitted digression of the measured capacitance from the rated value. Some capacitors are very easy to use following the series of their endurance. Their values are stated hereunder:
From the E3 series, the capacitance and tolerance capacity measured is ±20%, letter code "M."
In the series E6, measured capacitance and tolerance is ±20%, letter code "M."
For the E12 series, the valued capacitance and tolerance is±10%, letter code "K."
Advantages and Disadvantages of Electrolytic Capacitors
Most of the storage capacity levels that the electronic capacitors have been obtained from a layer of gas on one plate. It is possible only with the involvement of absolute polarity. The formula will be like: capacitance (C) is the magnitude of charge (Q) on every plate divided by the voltage (V) involved with the plates: C=Q/V. The presence of this gaseous layer and generous dielectric effect provides an electrolytic capacitor, comparatively more capacitance in volume, than the other forms of capacitors.
There are disadvantages, too, regarding the use of electrolytic capacitors. The possibility of leakage currents is very high in these capacitors. Value tolerances, equivalent series resistance capacity, and short life-span are some other drawbacks of these electrolytic capacitors.
Applications of Electrolytic Capacitors
It is used to prevent voltage fluctuations in different filtering devices.
When DC signal is weaker than AC, it is used as an input-output smoothing filter
These types of capacitors are primarily employed for filtering noise or decoupling in electric supply.
To control the coupling of signals between amplifier stages and to store power in flash lamps is another function of these capacitors.
FAQs on Electrolytic Capacitor
1. What is an electrolytic capacitor and what is its basic working principle?
An electrolytic capacitor is a type of polarised capacitor known for its high capacitance-to-volume ratio. Its working principle is based on creating an insulating dielectric layer through an electrochemical process. The anode (+) is a metal foil which, through anodization, forms an extremely thin layer of metal oxide. This oxide layer acts as the dielectric. A conductive liquid or solid electrolyte acts as the cathode (-), allowing for a very close spacing between plates and thus a very high capacitance in a compact size.
2. What are the main types of electrolytic capacitors students should know about?
There are three primary types of electrolytic capacitors, distinguished by the anode material and electrolyte used:
- Aluminium Electrolytic Capacitors: These use high-purity aluminium foil for the anode and typically a liquid electrolyte. They are the most common type, offering a wide range of capacitance and voltage ratings.
- Tantalum Electrolytic Capacitors: These use tantalum for the anode and a solid electrolyte (manganese dioxide or a conductive polymer). They offer superior frequency characteristics and stability in a smaller package than aluminium types.
- Niobium Electrolytic Capacitors: Similar to tantalum capacitors, these use niobium metal for the anode and are known for their reliability and stability.
3. Why is observing the correct polarity so crucial when using an electrolytic capacitor?
Observing polarity is critical because an electrolytic capacitor is designed to work with DC voltage in one direction only. The thin oxide dielectric layer is maintained by the correct forward voltage bias. If you connect it with reverse polarity, the insulating oxide layer breaks down, causing a short circuit. This can lead to rapid overheating, gas build-up, and may cause the capacitor to vent or even explode, damaging the circuit and posing a safety risk.
4. What are the key advantages of using electrolytic capacitors over other types like ceramic or film capacitors?
The primary advantage of electrolytic capacitors is their exceptionally high capacitance-voltage (CV) product per unit volume. This means they can provide a very large amount of capacitance in a small physical package, which is something ceramic or film capacitors cannot achieve as efficiently. This makes them indispensable for applications requiring high capacitance values, such as power supply filtering, energy storage, and signal coupling in audio circuits.
5. What are some common real-world applications of electrolytic capacitors?
Due to their high capacitance, electrolytic capacitors are found in many electronic devices. Common applications include:
- Power Supply Filtering: Smoothing out the rectified DC voltage to reduce ripple and noise.
- Audio Circuits: Used for coupling and decoupling signals between amplifier stages to block DC components.
- Camera Flashes: Storing a large amount of energy and releasing it quickly to power the flash tube.
- Timing Circuits: Used in combination with resistors to create time delays.
- Motor Starters: Special non-polarised electrolytic capacitors are used to provide an initial phase shift to start single-phase AC motors.
6. Can a standard electrolytic capacitor be used in an AC circuit? Explain the reasoning.
No, a standard electrolytic capacitor cannot be used in a pure AC circuit. The alternating nature of the current would constantly reverse the voltage across the capacitor. During the negative half-cycle, the reverse voltage would destroy the delicate dielectric oxide layer, leading to component failure. They are strictly designed for DC circuits or for AC signals that have a significant DC bias, ensuring the voltage across the capacitor never becomes negative.
7. What is the fundamental difference in construction between an electrolytic and a non-electrolytic (e.g., ceramic) capacitor?
The fundamental difference lies in the dielectric material and polarity. In an electrolytic capacitor, the dielectric is an incredibly thin metal oxide layer formed electrochemically on the anode, which is why it's polarised. In a non-electrolytic capacitor, such as a ceramic or film type, the dielectric is a stable, manufactured insulating material placed between two metal plates. This construction is more robust but results in lower capacitance for a given size and makes the capacitor non-polarised, allowing it to be used in any orientation in both AC and DC circuits.
