“It’s all part of the genie gig—phenomenal cosmic power... itty bitty living space.” In terms of this itty-bitty electrical component, the Genie in Disney’s Aladdin had it right. Capacitors provide a large amount of power in a compact vessel and are used in a wide range of electronics. They are a passive electrical mechanism charged by a current, with the ability to store energy within an electric field. This capability can be utilized to power a camera flash, remote signal, or even switch AC current to DC smoothly.
So how do these things work? Imagine a bar of chocolate covered Oreo on a stick. Though not edible and probably not nearly as delicious, a capacitor consists of two metal plates that act as conductors (the cookies), and dielectric material in their middle (the cream). These components are then dipped in a resin (the chocolate). This assembly is also attached to two electrical terminals that connect it to power and ground sources (the stick).
Now that we can imagine the structure, let’s look at how the capacitor holds its charge. An electrical current enters the capacitor and reacts with a metal plate, causing negative electrons to get trapped. The insulator material, or dielectric component, is non-conductive, and as one metal plate gathers electrons, the second plate becomes positively charged. With this interaction, an electrical field is formed, allowing the capacitor to hold a charge or a constant feed of tension between the negative and positive plates.
The versatility of these components has led to the development of the three most common variations: ceramic capacitor, the electrolytic capacitor, and the supercapacitor. Each of these works similarly to standard capacitor operations but vary in their level of charge and vulnerability to current leakage.
A ceramic capacitor is most often used on a breadboard or circuit board. They are the most rudimentary, the cheapest to acquire, and they leak the least amount of current. Despite these benefits, ceramic caps hold only a small charge and are not powerful enough for applications requiring higher voltage and/or higher electrical storage.
An electrolytic capacitor is most often seen on a circuit board. Capacitors of this category hold and generate a massive electrical charge while maintaining a compact design. Uniquely, these devices are also polarized. Due to this, they require specific wiring systems to function properly and are equipped with anode (+) and cathode (-) pins. Anodes connect to higher voltages and cathodes connect to lower voltages. These capacitors have the least current leak efficiency and are not best for storing energy.
Last, but certainly not least in energy storage, are supercapacitors. Energy storage and discharge capabilities of the supercapacitor rank the highest among these units. They release their charge all at once, resulting in a shorter lifespan and vulnerability to high voltage situations.
If you are considering the use of a capacitor, there are a few variables to keep in mind. Size, max voltage, and current leakage are all elements that you will want to check with any capacitor. Overall, capacitors are small electrical units capable of high energy storage and discharge. The itty-bitty battery like structures can benefit any project needing a smoother current, capacitor coupling, tuning, or energy storage.