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The Difference Between Fixed and Variable Inductors

30 May, 2019 | Quest Components

The Difference Between Fixed and Variable Inductors

An inductor, also known as a choke, a reactor, or a coil, is a passive two-terminal electrical energy storage device made from a core that is surrounded by a coiled, insulated wire. When electric current flows through the inductor, its magnetic field stores energy. Inductance is the amount of energy that an inductor can store. Its unit of measure is the henry, named for American scientist Joseph Henry.

Common Applications for Inductors

Inductors are used in many different applications, primarily analog circuits and signal processing. Very large inductors can be paired with filter capacitors to remove ripple from power supplies, while very small inductors can prevent radio frequency interference. In switched-mode power supplies, inductors may be used as energy storage devices for DC current, keeping current flowing when the switch is “off” and allowing the output voltage to exceed the input voltage.

An inductor connected to a capacitor creates a tuned circuit that serves as a resonator for oscillating current. These are often used in radio transmitters and receivers, as well as in electronic oscillators. A transformer consists of two multiple inductors with mutual inductance. Transformers are an important part of any power grid.

Fixed Inductors

A fixed inductor will always have the same inductance. Types of fixed inductors include air-core, iron-core, and ferrite-core. Fixed inductors tend to be more compact and more convenient than variable inductors, making them an excellent choice for applications in which steady inductance is desired.

Variable Inductors

A variable inductor lets the user control the inductance by changing the position of its ferrite core. Moving the core deeper into the coil increases the permeability, which increases the inductance. Moving the core further out of the coil lowers the permeability and, consequently, the inductance. Variable inductors are commonly used in radio and other applications that require specific tuning. A variable inductor is also used in highly sensitive applications since a fixed inductor may not be perfectly aligned in these situations.

Inductor Problems

Although they are very common and highly useful, inductors are not without problems. They can both create and suffer from electromagnetic interference. Their size prevents their use on semiconductor chips. Therefore, inductors are increasingly being replaced on modern electronic devices, particularly those that are small and portable. For example, the gyrator can mimic the behavior of an inductor in a capacitor. Still, for many applications, a genuine inductor is the best choice.

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Here at Quest Components, we are committed to providing you with the information you need to help your business continue to run smoothly. An ISO 9001:2015 Certified Company headquartered in Industry, CA, Quest Components specializes in passive and active board level components. We also provide a variety of services to OEMs (original equipment manufacturers) and CEMs (contract electronics manufacturers) across the globe. Contact Quest Components today at 626-333-5858 for all your electronic component needs!

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