What Is an Inductor? A Practial Guide for Hobbyists

The inductor is a simple component, and how it works is also pretty simple. The only problem is that most explanations do not explain it in a simple way.

So, what is an inductor? Well, it’s kind of a strange component. At the most basic level, it is just a coil of wire. And it’s easy to make one — just make some loops with a wire.

But wires actually create magnetic fields. And that means the inductor behaves in an interesting way and can do interesting stuff.

A simple homemade inductor

The Inductor in a Circuit

If you’re learning electronics, the first important question is: What does the inductor do in a circuit?

An inductor will resist changes in current.

In the circuit below, you have an LED and a resistor in series with an inductor. And there’s a switch to turn the power on and off.

Without the inductor, this would just be a normal LED circuit and the LED would turn on right away when you flip the switch.

But the inductor is a component that resists changes in current.

When the switch is off, there is no current flowing. When you flip the switch on, the battery will try to get current flowing. That means there is a change in current which the inductor will resist.

So instead of the current going from zero to maximum right away, it will gradually increase up to its maximum current.

(The maximum current for this circuit is set by the resistor and the LED.)

Since the current decides the light intensity of the LED, the inductor makes the LED fade in instead of turning on instantly.

Animation showing the current through inductor and LED

Note: You’d need a very large inductor to be able to see the LED fade in the circuit above. It’s not something that you’d use an inductor for. But use it as a mental image of what the inductor does in a circuit.

What Happens When You Disconnect the Inductor?

The inductor also resists the current from switching off instantly. The current won’t just stop flowing in the inductor in an instant.

So when you switch off the power, the inductor will try to continue the current flow.

It does this by quickly increasing the voltage across its terminals.

It actually increases so much that you can get a little spark across the pins of your switch!

This spark makes it possible for the current to keep flowing (through the air!) for a fraction of a second until the magnetic field around the inductor has broken down.

That’s why it’s common to place a diode in reverse across the coil of a relay or a DC motor (called a flyback diode). This way, the inductor can discharge through the diode instead of creating high voltages and sparks in the circuit.

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How Inductors Works

Any wire with current flowing through it has a small magnetic field surrounding it.

When you wind the wire into a coil, the field becomes stronger.

If you wind the wire around a magnetic core, such as steel or iron, you’ll get an even stronger magnetic field.

This is how you create an electromagnet.

The magnetic field around it depends on the current. So when the current changes, the magnetic field changes.

When the magnetic field changes, a voltage is created across the inductor’s terminals that oppose this change.

What Can You Use Inductors For?

It’s not that common to see discrete inductors in the typical example circuits for beginners. So if you’re just starting out, you probably won’t come across them just yet.

But they are very common in power supplies. For example, to create a buck or boost converter. And they are common in radio circuits to create oscillators and filters.

What you will come across much more often though, is electromagnets. And they are basically inductors. You’ll find them in almost everything that moves from electricity. Like relays, motors, solenoids, speakers, and more.

And a transformer is basically two inductors wound around the same core.

If you want to learn how the other electronic components work, continue to the basic components in electronics.

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21 thoughts on “What Is an Inductor? A Practial Guide for Hobbyists”

  1. Good sir or ma,please i want know how to build the motherboard of lnverter and how to arrange the compoment please tell me what to do

    Reply
  2. Thanks Dear,I appreciate your efforts in educating us.
    Sir,I believe students learn easily when difficult problems are presented graphically.
    Sir, please can you explain how an inductor work as a filter and as an Oscillator using circuit diagrams the way you did in transistor and LDR circuit explanations.
    Thanks sir as I wait for your response.

    Reply
  3. im afraid to make a coil, because i read somewhere that everything depending on how to create a coil. I dont know how that stands true, but i cant just create coils myself. The coil wire are very expensive and i have to know the exact thickness of a coil wire in mm², the exact number of turns, the exact distance between turns, the thickness of enamel… All i said, is true, or i can make coils, worrying only about thickness and turns of a wire?

    Reply
  4. Me and my freind are starting a company where we are selling electronic kits and the first kit we are creating is an fm radio and he left me the responsibility because I know more about electronics than him. But I have never made a successful FM radio and need some help do you have any advice?

    Reply
    • My advice would be to find several sources for FM circuit schematics and try to build several of them. Hopefully you’ll make one of them work. Then try to understand why that worked and the others didn’t.

      Reply

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