Capacitor Buying Guide: Meaning, types and things to consider before buying
Capacitor is a device which is used to store electric charge in an electric field, and its effect is called capacitance. Capacitors are widely used in electrical appliances and are indeed an essential component for proper and safe working of these appliances!
Capacitor is a passive two terminal electrical component, capacitors contain two electrical conductors, which are made of metals like aluminium, with an insulator or dielectric in between, separating the two conductors. This dielectric works to increase the charge capacity. The energy is stored in a capacitor as an electrostatic field.
A capacitor is said to have a larger capacitance when the separation or the dielectric is narrower, while the surface area of the conductors is large.
The use of a capacitor is that it blocks direct current and lets alternating current pass. In case of analog filter networks, a capacitor would help in making the power supply smoother. In case of electric power transmission systems, capacitors are used for providing stability to power and voltage. Similarly, different systems have different uses of capacitors, be it power conditioning or pulsing power, but one thing is sure, it is vital!
So, if you are looking for a capacitor but are unsure about which capacitor and what kind to buy, then you have stumbled upon the right place. We have compiled all the necessary information that will surely aid you in your buying journey.
Types of Capacitors:
Firstly, let us take a look at the types of capacitors that you might need depending upon your requirement.
For large capacitance an electrolytic capacitor is the right choice. One of the electrodes is of thin metal layer and the other is a semi liquid electrolyte solution, while the insulator is made of an oxide. These electrolytic capacitors are mainly used in DC power supply circuits, as they require larger capacitance and little voltage. This capacitor helps in coupling and decoupling. The only downside is that the voltage is very low. Other than that it is perfect for large capacitance.
In this Mica is used as the dielectric. Mica capacitor has two variations clamped capacitor and silver mica capacitor. The former is deemed outdated and is no more advised to use. The latter, however, is formed by sandwiching sheets of Mica with metals on either side. To protect this arrangement it is then hemmed with epoxy. This capacitor is ideal when small but stable capacitance is required. These also have a very less energy loss and high frequency.
Film capacitors use a plastic as dielectric. It is made by using the process used to draw films. There are two kinds available, radial lead and axial lead. The electrodes may be of aluminium or zinc. These have a large size and are expensive. But, since these are available in numerous voltage values. These are also not polarized, which implies they can be used with AC voltage. These are best known to provide low inductance and stability.
Ceramic capacitors use porcelain as dielectric, this porcelain is coated with ceramic with silver on either side. Since it takes the shape of a disc, it is often called disc capacitor. By changing the thickness of the disc, the capacitance can be altered. The voltage goes up to thousands. Ceramics can be manufactured at low price and they also come in various kinds of dielectric. These are best suited for high frequency circuits.
Non Polarized Capacitor-
Non polarized capacitors do not have polarities, i.e., positives or negatives. There are two types of non polarized capacitors. The first, plastic foil capacitor, is non polarized by properties, but the second type-electrolytic non polarized capacitor is just two capacitors placed back to back thus making them non polarized. These have small capacitance. These are the best fit for AC circuits and high frequency filtering.
A paper capacitor consists of a paper as dielectric which separates two tin foils. This construction is then rolled into a cylinder. This is the most primitive type of capacitor and is either not used at all, or the paper is replaced with other dielectrics like plastic.
Things to consider before buying a capacitor:
Now that you are well aware of the major kinds of capacitors that are available in the market, you might want to consider a few things that will help you decide which one you actually need.
Capacitors are generally polarized. They have a positive and a negative terminal. In such capacitors voltage is applied to one terminal and it moves in one direction. However, there are capacitors which are not polarized and the voltage in these can move in either direction. So, you need to make a decision about the polarity and direction.
With the increase in temperature, any electrical property of the capacitor gets increased. It is said to have a positive temperature coefficient. While, if there is a decrease in any property with decrease in temperature it is said to have negative temperature coefficient. Different capacitors have different levels of variation with temperature, which affects the overall performance if it is being used in any appliance which heats up. So, you need to make a wise decision in this aspect.
The dielectric loses some current while in operation. This current loss needs to be minimized as it degrades the performance. So, go for a capacitor that has a good insulation that can effectively minimize this loss.
Working voltage tells about the voltage, AC or DC, that can be applied continuously across the terminals over its lifespan. Different capacitors have different voltages. Electrolytic capacitors have low voltage, while ceramic capacitors have high voltage. So, be specific with your voltage requirement.
Capacitors have different ranges for all the electrical properties like capacitance, resistance and so on. So you must be sure of all the ranges you would want to have the capacitor in. Depending on the value ranges, you will be able to make out which type to go for.
The most important factor is the capacitance price. Depending upon the dielectric and the electrode material, the cost of the capacitance will vary. Capacitors that are to be used in household appliances can be availed at low prices, but if you are looking for capacitors for big factories or laboratories that deal with higher values and have larger tolerance, then you must be willing to spend more bucks.
This was all the must have information about capacitors that will thoroughly guide you to find the best type of capacitor at the best price. Work through all the tips and find the best suit for you. Do make sure you are willing to spend a little more if required for the quality of the product, as these devices although small, can immensely affect the overall functioning of the circuits or systems...!
Q. What is a capacitor used for?
A. The main usage of capacitors is to store electrical charges, which can be released to the circuit whenever required. Besides, these devices also used to filter voltages or bypass current from one circuit to another.
Q. What is a capacitor and how it works?
A. A capacitor is mainly an energy-storing device that is one of the most important components in all major electronic appliances like TV, computer, laptops, fans, washing machines, fridge, oven, and so on.
Q. What are the types of capacitors?
A. There are many other types of capacitors such as ceramic capacitor, electrolytic capacitor, tantalum capacitor, variable capacitor, paper capacitors, film capacitors, polarized capacitor, mica capacitor, super capacitors, teflon capacitors, special purpose capacitors and more.
Q. Are capacitors AC or DC?
A. You have both AC and DC capacitors. While AC Capacitor have no polarity, DC capacitors have polarity ( positive and negative).