Capacitors: How They Work
The capacitor is an extremely useful and common electronic component within modern circuits and devices. It is a passive electrical component used to store electrical energy in an electrical field. The function carried out by a capacitor is referred to as capacitance. Capacitors are made up of two closed conductors called plates separated by a dielectric material. An electric charge is created when the plates come into contact, with one plate accumulating the positive charge and the other plate accumulating the negative charge. As capacitors play an important role in electronic devices, there are many variants intended for different applications. This blog will explain each of the six types of capacitors, their functions, and their uniquities.
- Electrolytic Capacitor
These are typically used in applications where large capacitor values are needed. They feature a thin metal film layer for one electrode and a semi-liquid electrolyte solution for the second electrode. The dielectric plate is a thin layer of oxide, developed electromechanically. The insulation layer is extremely thin, allowing for capacitors to have large values of capacitance despite being small in size.
- Mica Capacitor
There are two types of mica capacitors: clamped & silver mica. Clamped mica capacitors are now considered obsolete due but silver mica capacitors remain in wide use. They are made by placing metal-coated mica sheets on both sides of the dielectric before the construction is encased in epoxy. Mica capacitors are low-loss capacitors, used at very high frequencies. They are very stable chemically, electrically, and mechanically due to their layered, crystalline structure.
- Paper Capacitor
Paper capacitors consist of two tin foil sheets separated by a thin piece of oiled or waxed paper. The foil and paper is then rolled into a cylinder and enclosed in a plastic capsule. The tin foil attaches to the external loads of the capacitor. Paper capacitors feature a capacitance range from 0.001 to 2.000 microfarads.
This type of capacitor is prepared through an extremely sophisticated process of film drawing. The film is manufactured to specially accommodate the properties of the capacitor it will be used in. Different materials such as polyester, metalized, polypropylene, PTE, and polystyrene film are all available. This type of capacitor provides stability, low inductance, and low cost. These capacitors are extremely popular in the aerospace and defense industries, due to their high heat resistance.
- Non-Polarized Capacitor
These are classified into two types - plastic foil capacitors and electrolytic non-polarized capacitors. The plastic foil capacitors are innately non-polarized, and the electrolytic capacitors are installed back to back, making them non-polarized with half the intended capacitance capability. Non-polarized capacitors require alternate current in their signal or power supply.
- Ceramic Capacitors
The final type of capacitor uses ceramic material as a dielectric. The ceramic dielectric is attached to the electrode and a connecting wire, which is then covered in a protected coating. The two most common types of ceramic capacitors are the multilayer ceramic capacitor (MLCC), and ceramic disc capacitor. Ceramic capacitors can range from 1 farad to 100 microfarad.
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