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What Are the Differences Between Fixed and Variable Capacitors?

Capacitors are a type of device that stores energy similar to a battery. However, the charge in a battery is stored as chemical energy, whereas the charge in a capacitor is stored in the form of an electrostatic field. As such, they are commonly found in power supply units, air conditioning systems, appliances, lighting systems, and more. In general, the majority of capacitors can be classified as either fixed or variable with different usages for each.

What Are Capacitors?

As stated before, capacitors store energy in the form of an electric field. In general, capacitors cannot store as much energy as a battery, but they can charge and release their energy much faster. This makes capacitors very useful so that they have become a common component in nearly every circuit board. Due to their quick charging and release, capacitors are usually hooked up into a circuit for the purpose of maintaining a steady stream of current despite regular interruptions. For example, you could link a capacitor to a battery on one end and an LED on the other. While the battery is still connected and has a charge, it will continually feed energy to the capacitor which will then charge up and send current to the LED. If the battery needed to then be disconnected and replaced, the capacitor would take over, emptying its charge until it runs out or a new battery is installed. As such, a capacitor can be added to a circuit to maintain a current during small interruptions, minimizing potential downtime.

What Is the Difference Between Fixed and Variable Capacitors?

Though many variations exist, the majority of capacitors can be separated into two categories: fixed and variable. As the name would suggest, fixed capacitors have a fixed capacitance. This means that the capacity of the device to hold an electric charge will remain at the same value and cannot be adjusted. Of the two types, fixed capacitors are the most common and have far more applications than variable capacitors. However, there are certain operations that can only work with variable capacitors. Rather than remaining fixed, the capacitance of these devices can be adjusted throughout their service life. Additionally, they can be broken down into several subtypes. For example, trimmer capacitors are used in radio frequency (RF) applications, whereas tuning capacitors are used to resonate frequencies. Other specialized types exist for different applications. To suit different environments and demands, both varieties can come in varying materials, such as ceramic or plastic with a film foil.

Applications for Capacitors

The most common use for capacitors is energy storage, but they can also be used for power conditioning, signal coupling or decoupling, electronic noise filtering, and remote sensing applications. When considering the two categories, fixed capacitors are used in most circuits as a way to safeguard and control the flow of current. Conversely, the adjustability of variable capacitors makes them useful in specialized applications, such as filters, where they can be adjusted to provide a desired frequency response. Variable capacitors are also found in sensors and controls where the ability to adjust the level of current is required.


Capacitors are energy-storing components that can be found in circuitry across many operations. By providing fast charging and rapid release of stored energy, they can be used to help safeguard, filter, or control the flow of current in an electrical system. On Industrial Part Numbers, you can find a wide array of quality-tested IT hardware and electrical components, such as fixed and variable capacitors. To find a specific part or browse our various offered items, you may use our easy-to-navigate online catalog and search tools. We invite you to take advantage of our 24/7x365 RFQ service to receive quotes for your comparison on any item of interest within just 15 minutes of receiving your completed form.


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