Like everything else in the world, there’s more than one way to shear a sheep.. Or make a capacitor. We need something that stores a charge and quickly blasts it out. There are it turns out, a lot of ways to do this. Each type of capacitor has its own special advantages and disadvantages.
Three Major Types
We can broadly break capacitors down to three varieties: electrolytic, ceramic, and film. These all store and discharge power, but they come in different packages and do it all a little differently.
These are the big capacitors that power your compressor motor, sit in your computer’s power supply, and otherwise do heavy-lifting. They’re generally cylindricaly shaped and contain a liquid electrolyte between metal plates in a coil. The major advantage is in scale, these capacitors tend to start at a micro-farad and go up from there. Their major limitation is in frequency. They really cannot be used above 100khz. This limits them to ‘slow’ applications as power supply components.
Higher frequencies call for a faster, solid-state approach. These capacitors are composed of ceramics and metals, often layered like a sandwich back and forth inside a surface-mounted package. This type of capacitor is very difficult to replace, it’s a tiny component on a circuit board, requiring expensive microscopes and soldering equipment to replace. When these fail, you’ll normally replace the entire board they’re on. These can be found in the circuit boards for basically everything. They’re in your phone, computer, furnace controller, thermostat, and more.
This design is a little weird. These capacitors are incredibly scaleable, used everywhere from appliances to massive industrial scale applications. They’re built similar to ceramic capacitors, but with plastics and varying compositions of metals and oils, almost like an electrolytic capacitor. In function, they’re more like several capacitors in series, which reduces inefficiency.
The shear combinations of metals and plastics involved is what brings the flexibility. A manufacturer can make them work wherever they’re needed. The design doesn’t inherently face the same limits as the others because it acts like smaller capacitors put together, limiting some of the complications.
Is That All?
This is the most barebones look we could do. Most other capacitor designs stem from these three base concepts. There are further tantalum capacitors, metalized film capacitors, a half dozen different types of plastic-varieties used for the film capacitors, and more. A full look would be at least a dozen capacitors, each suited to a special application or need.