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Introduction to Fixed, Array, Variable, & Network Capacitors | Questcomp.com

06 Nov, 2019 | Quest Components

Introduction to Capacitors

A capacitor is a tool for storing energy. It is different from a battery in that it stores energy in an electromagnetic field rather than in a chemical state. There are different types of capacitors that are made of different materials with different capacities.

If you have experience using capacitors in electrical circuits you may already know which types are available and how you use them. But if you’re new to new to the electronic component industry or to using capacitors, here is some basic information to get you started.

What Does a Capacitor Do?

A capacitor, when added to a circuit, stops the flow of electricity as it is moving through the circuit and captures it, thus creating an electromagnetic field that stores that energy. The energy builds within the electromagnetic field until it reaches capacity (the amount of energy it is capable of holding). The electricity then moves on through the rest of the circuit.

How Does a Capacitor Work?

A basic capacitor consists of two metal plates positioned parallel to each other with an insulating material between them. The insulating material (called a dielectric) could be waxed paper, mica, ceramic, plastic, or even a liquid gel. The electric current cannot pass through the capacitor because of the dielectric, so it creates an electric charge between the plates, or a voltage.

When direct current passes over a capacitor it causes the plate at one end to accumulate a positive charge (by gathering protons) and the plate at the other end to accumulate a negative charge (by gathering electrons). In this way the capacitor is similar to a standard household use battery with a positive and negative end.

A capacitor is actually more like a rechargeable battery. It collects energy until the voltage within the capacitor is the same as the voltage being applied. It is then considered to be fully charged.

Types of Capacitors

Fixed Capacitors: A fixed capacitor has a specific capacitance that is not adjustable. It is only able to hold a certain fixed amount of charge or energy. For example, the multilayer ceramic capacitor GRM188R71E104KA01D is a fixed capacitor from Murata Manufacturing and has a fixed capacitance of 100nf (or sometimes referred to as 0.1uf) and a fixed voltage of 25 volts.

Variable Capacitors: A variable capacitor can be mechanically adjusted to change the amount of energy it can hold, or its capacitance. This variable ceramic capacitor, TZBX4R200BB110T00, is surface mounted with a vertical adjuster. You can adjust the capacitance value of this part from anywhere in the range of 4.5pf to 20pf. The voltage will remain the same though, and is not adjustable.

Arrays and Network Capacitors: An array or network of multiple capacitors saves physical space on a circuit board and reduces the cost of placing multiple capacitors of the same value (this is important for mass production). Since every designer/engineer is constantly striving to reduce the size of whatever device they are designing, capacitor arrays help them accomplish that by saving space. Otherwise, by using multiple individual capacitors, the total space needed on the circuit board would be greater. An example would be a 4-capacitor array network capacitor, such as ECJRVB1C104M. This Panasonic capacitor array has a capacitance value of 100nf (or sometimes referred to as 0.1uf) at 16 volts per individual capacitor. So, if the circuit called for 4 100nf, 16 volt capacitors, just one of the ECJRVB1C104M can be used instead.

What Determines the Amount of Energy a Capacitor Can Hold?

There are a few different factors in a capacitor that affect the amount of energy or voltage that a capacitor can hold in its electromagnetic field.

Size of the plates. The larger the metal plates that hold the charge between them, the greater the capacitance.

Distance between the plates. The closer together the metal plates are, the greater the capacitance.

Dielectric material The dielectric material that exists between the plates affects the capacitance. Examples of dielectrics categorized by type:

  • Polarized capacitors: electrolytics, tantalums
  • Medium Loss, Medium Stability: High-K ceramic, paper, plastic
  • Low Loss, High Stability: polystyrene, Low-K ceramic, mica

Why Are Capacitors Important?

What does a capacitor do for a circuit that is beneficial? Generally speaking, a capacitor improves the electrical performance of the circuit. Its ability to store energy can be helpful in many ways when it comes to a variety of electronics.

Prevent a voltage spike. In systems where voltage could potentially spike or surge without warning, the capacitor can absorb that impact, preventing damage to other electrical components.

Absorb audio noise. A voltage spike could also cause an audio disturbance that may be quite loud. The capacitor can absorb the sudden increase in voltage and prevent an audio disturbance.

Prevent disruption of power. If there are gaps in the power supply, the stored energy in the capacitor can keep the voltage even so that there is no disruption of power.

Achieve optimum power factor. In high power systems, adding capacitors to achieve an optimum power factor can keep costs down.

Find an Extensive Inventory of Capacitors at Quest Components

Whatever type of capacitors you’re looking for, from fixed capacitors to arrays and network capacitors, you can find it at Quest Components. Search current inventory of Questcomp capacitors here.

If you’re not sure what type of capacitor would best suit your needs, call (623) 333-5858 today to speak with a representative, or reach out to us via our Contact Us Page. At Quest Components, we understand electronics and strive to get you the parts you need promptly. We look forward to serving you.

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