Capacitors: Fixed & Variable Capacitors


A capacitor is a type of electronic component that is capable of storing energy in the form of an electric field. As a passive component that features two terminals, capacitors are regularly implemented within circuits to add capacitance. With a variety of types existing across the market, capacitors can benefit a range of applications including energy storage, power conditioning, suppression and coupling, digital memory, and much more. To best understand what capacitors are and how they may be used for a particular system, it can be helpful to be aware of the most common types and their functionalities.

In their most basic form, capacitors contain two conducting surfaces that are parallel to one another while separated by air or a dielectric non-conducting material. Connected to a voltage source, one plate is positively charged while the other negatively charged. Somewhat similar to a battery, the capacitor will retain this charge until its plates come into contact, causing the energy to instantly dissipate.

Fixed capacitors are one of the two main categories for classification, and they are types that have non-adjustable conducting surfaces. For fixed capacitors, the most common types include paper, plastic, ceramic, and electrolytic capacitors. Paper capacitors are ones in which a wax covered paper serves as the dielectric. Layered in aluminum and then rolled into a cylinder, two wires can be added to connect the capacitor to a voltage source so that it may serve high voltage applications. With plastic capacitors, plastics are used as the dielectric and such components may be film foil or metalized film types. Ceramic capacitors are a type that can gather a large charge for limited spaces, and their ceramic materials serve for efficient insulation. With the mica capacitor, stability and reliability is provided for both low and high voltage applications. Mica capacitor types also come in two forms, those being stacked mica capacitors and silver-mica capacitors. Lastly, electrolytic capacitors have large capacitance capability, and they utilize aluminum oxide sheets for their dielectric and electrolytic soaked paper for their conductor.

Variable capacitors are the other major capacitor type, and they can change their capacitance through the physical or electronic adjustment of plates. For variable capacitors, tuning, trimmer, mechanical, and electronic capacitors all serve as the most common types. The tuning capacitor type is one regularly used in radio equipment, allowing for the user to tune into stations. For early radios, a knob would be provided in order to adjust the distance between capacitor plates. Trimmer capacitors are regularly used for the calibration of newly manufactured equipment, and they may often be found on printed circuit boards for making small adjustments. The mechanical capacitor features semi-circular plates that are connected to a knob, allowing for their capacitance to quickly be adjusted in an easy way. Lastly, electronic capacitors are capable of changing their capacitance as they are induced with DC voltage. This can be very beneficial for applications such as multi-meters, allowing them to measure voltage, resistance, and amperage.

With the various types of capacitors, numerous applications can benefit from their ability to store electric charges. If you are in need of capacitors or other electronic components for your operations or maintenance endeavors, look no further than ASAP Aviation Unlimited. As a premier purchasing platform owned and operated by ASAP Semiconductor, we serve as an online distributor of aircraft parts that have been sourced from top global manufacturers that we trust. To ensure that our customers only receive what is best, we subject each and every item to through quality assurance testing and inspection prior to shipment, and we are the only independent distributor with a strict no China sourcing pledge. Get started today and see how we can serve as your strategic sourcing partner for your operational needs.



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