What Is a Capacitor and What Is It Used For?

Learn how capacitors work and what they're used for so that you can properly implement them in your next DIY project.

Once known as condensers, capacitors are one of the most common components used in circuitry. It’s easy to follow DIY guides that use components like this without knowing what they are for or how they work, but it doesn’t take much to learn.

So, what is a capacitor, and how do they work? Let’s find out.

What Is a Capacitor?

Capacitors (originally called electrical condensers) are analog electrical components that can collect and store electrical energy. As a direct current flows into a capacitor, it charges with energy and releases an alternating current flow back into the circuit.

Most capacitors have a positive and negative terminal in the form of legs, pads, or plates. Current flows into one of these legs, through the capacitor's body, and out of the other leg.

These components give engineers the ability to control electrical energy within a circuit. Voltage spikes get ironed out, and energy can be stored for later use, all using clever chemistry inside the capacitor itself.

Capacitors are often compared to batteries, but they are quite different. Unlike batteries, you can discharge a capacitor almost instantly, and they aren't made for long-term energy storage.

What Is Capacitance?

Capacitance is the ability of a component to store electric charge and can be measured with units called Farads. A capacitor with high capacitance (say 1.0F) can store more energy than one with low capacitance (say 1.0mF).

While capacitance is important when choosing a capacitor, the voltage limits of the component are also critical.

What Is a Capacitor Used For?

Capacitors are ubiquitous in the modern world. You don't see them, but these components are at home in just about every electrical and electronic device you use. So, what does a capacitor do in these devices?

Let's look at some of the most common applications for capacitors.

• Camera flashes: Before LEDs hit the scene, camera flashes used small filament bulbs to produce light. A vintage camera couldn't provide enough power to create a bright flash without an overly-large body. Capacitors solved this problem by charging up and storing energy before every flash. This is an example of pulsed power.
• Computers: Volatile storage, like RAM, loses the data stored when it loses power. This creates a problem when power supplies need to be changed, but a capacitor can solve this problem by providing temporary power. This is an example of energy storage.
• Analog stereo equipment: Amplifiers and other analog stereo equipment require precision circuitry to provide clean audio. Capacitors smooth current fluctuations in circuits like this, reducing hum and unwanted noise. This is an example of power conditioning.

Here, we merely scratched the surface of capacitor use throughout the world. Several everyday devices contain dozens, if not hundreds, of capacitors that perform unique roles.

Using Capacitors for DIY Projects

Now that you have a basic understanding of how a capacitor works, you can use these components for various applications. Putting capacitors to work in your own circuits will take some learning, but it will be worth it. Therefore, it's worth doing some research for yourself to spark your inspiration.