Capacitor, Functions and Types

By | September 4, 2021

Capacitors are the most widely used passive electronic components in circuits after resistors. Capacitors are passive electronic components that can store electric current for a certain period of time. Capacitors are like batteries, but with a lower charge-holding capacity.

The inventor of the Capacitor is Michael Faraday, an Englishman. His name was then used in the capacitor value unit, but because farada is a very large value, the naming is often converted into smaller units, in order of smallest:

1nF = 1000pF (pico Farad)

1µF = 1,000,000pF (piko Farad)

1µF = 1000nF (nano Farad)

1 Farad = 1,000,000µF (micro Farad)

 

Capacitor Symbol

In electronic circuits this component is abbreviated to the letter C, here are the symbols on the circuit:

capacitor symbol

 

Types of Capacitors

Based on the value, it can be divided into 2,  Fixed Value Capacitors and Variable Value Capacitors (the value can be changed) , the following is an explanation

Fixed Value Capacitor

This type of capacitor has a capacitance value that cannot be changed and is generally made of material, mica, paper, or ceramics. The value range can  from the pico farad unit to the largest unit, the farad.

The way to read the capacitor code is very easy, namely by looking at the body of the component which consists of 3 numbers where the first and second digits are values ​​while the third digit is a multiplier or the number of zeros. There are several types of Fixed Capacitors, namely:

  1. Ceramic Capacitor

Ceramic Capacitors are capacitors made of ceramic material. Capacitors of this type are usually thin round or square. Because of its non-polar nature, ceramic capacitors can be installed back and forth in electrical circuits. For the value itself usually has a small capacitance from 1pF (piko farad) to 0.1 uF (micro farad) but the voltage rating is very low.

How to read this ceramic capacitor, for example, if we have a capacitor with the code 103, it means that the 10 and 3 digits behind it become 10,000 pF which in larger units becomes 10 nF (nano Farad).

ceramic capacitor

 

  1. Polyester or Mylar Capacitor

In this type,  the insulating material consists of polyester, most of which tolerances range from 5-10%. From its shape it is usually box-shaped and there is no (+) / (-) polarity. The range of values ​​is also quite varied but generally in clear capacity and low voltage usage.

Because the tolerance is large enough, it is usually not used in high-frequency circuits or circuits with large currents, but in power supply circuits it is quite widely used.

The following is the form of a Polyester / Mylar capacitor:

polyester capacitor

  1. Mica Capacitors

As the name implies, the insulating material uses mica and its use is usually in high-frequency RF circuits. This is because of its low tolerance and high stability as well as excellent temperature resistance and most importantly it can be used at high voltages so the price is also quite expensive.

Another function of the capacitor apart from being an RF oscillator is also as a filter, coupling or decoupling. The following is the form of a Polyester capacitor:

mica capacitor

 

  1. Electrolytic Capacitor

Capacitors are also commonly called elko is a type that is quite widely used and is generally in the form of a tube. In the installation must be careful because it has a polarity (+) and (-) if it is reversed, the consequences are fatal because it can explode.

The value of its capacity is also usually large with a high voltage as well. Capacity can range from 0.47 uF to Farad units. The insulating material consists of a liquid electrolyte to store electrical energy which is then wrapped again with aluminum.

The use of electrolytic capacitors is usually in low-frequency circuits such as amplifiers, or power supply circuits. The following is the form of an electrolytic capacitor:

Electrolytic Capacitor

 

  1. Paper Capacitors

The insulating material consists of a layer of paper combined with a layer of aluminum to store the charge and usually the capacitance value ranges from 300 pF to 4 uF only with legs that have no polarity so it’s not a problem if it is reversed.

Generally used in electronic circuits that have high current and voltage. Here is the shape of a paper capacitor:

paper capacitor

 

  1. Tantalum Capacitors

This type of tantalum is widely used because it provides a varied range of capacities and good tolerances, so it is widely used on mainboard PCs or on cellphone and laptop modules.

What must be remembered, although the shape is similar to ceramic or polyester capacitors which do not have a polarity, the tantalum type has a polarity so that it should not be reversed for installation. Named tantalum capacitor because the positive terminal leg uses tantalum metal. The following is the physical form of a tantalum capacitor:

tantalum capacitor

 

From the price it is also expensive because there are several advantages, namely very efficient where the components are small but the capacitance is large, another advantage is that it can be used in a wide frequency range, for example at high frequencies.

Just compare it with electrolytic capacitors which do have a large capacitance but can only be used in low-frequency circuits. There is another advantage that it is resistant to temperatures from -55C to +125C which makes it very suitable for use in circuits that are required to have high durability.

Variable Value Capacitors

The purpose of the variable is that it can be changed as needed and there are only 2 types of capacitors, namely Varco (Variable Condensator) and Trimmer.

Both have low capacitance and there is a mechanical control to be able to change the capacitance which is not more than 500 pF, this type of variable capacitor is widely used in L/C circuits that function to regulate frequencies such as radio.

  1. Trimmer

To change the capacitance on the trimmer, a minus screwdriver is needed because the adjusting shaft is very small. The trimmer consists of 2 metal plates combined with mica material, the way the trimmer works is when the shaft is rotated it will change the plate distance so that the capacitance changes.

Because the adjusting shaft can only be done with a minus screwdriver, it is usually only for fine tune circuits / one setting. The maximum value of this type of capacitor is only 100 pF, the following is the symbol and physical form of the trimmer:

trimmer capacitor

 

trimmer capacitor symboil

  1. Varco (Variable Condensator)

In this type there is a shaft to change the capacitance of its own shape, usually in the form of a box with a capacity value ranging from 100 pF to 500 pF. The function of this capacitor is widely used in RF circuits, for example on radios. The following is the symbol and physical form of Varco:

variable capacitor

variable capacitor symbol