Variable Capacitor – Electronic Or Mechanical Storehouse Of Energy

A variable capacitor is a condenser, which is useful in storing energy by creating electric fields. The specialty of this device is that the ability to retain power can be changed either repeatedly and intentionally through electronic or mechanical ways.

The capacitance of the variable capacitor may be changed throughout the lifespan of the device itself. A mechanical construction is used in the capacitors, which allows changing the distance between the various sets of plates, or precisely, the area of the overlapping plate surface, including the variable capacitance diodes. All these change their nature of capacitance due to the application of reverse voltage bias.

Uses and Applications of a Variable Capacitor

Capacitors usually deal with almost every person on this earth. The most common device that we use in our daily lives, the radio, depends on the variable capacitor values for receiving the various channels over the air. The capacitor helps in adjusting the radio to accept the variety of frequencies over which the different channels are broadcasted. Tuner of the radio is a very common example of a variable capacitor.

In fact, without this wonder device, the transmission of television would have been practically impossible. The capacitance of the semiconductors, which is controlled through bias voltage, determines the function of the supersensitive transformers. This in turn helps in the radical change of direct voltage into an alternating voltage pattern.

The main advantage of this device is that while it helps in storing electrical or mechanical charges, it can simply be adjusted according to needs for storing a variable amount of electricity. These capacitors are commonly found in radio sets, as channel tuners. These devices can be used to change the storage quantity of electrical or mechanical charge. A typical variable capacitor has a comparatively lower capacity of storing the charge.

The method of variable capacitance is even applied in pressure sensors and even the microphones.

Types of Variable Capacitors

Several types of variable capacitor are available. They are as follows:

  • The air variable capacitor is a device possessing a rotating and a fixed set of metallic plates that is positioned in a meshed-fashion. They are separated by air. The energy-retaining power is controlled through rotation of a set of plates that vary in overlapping with the fixed set of plates.
  • The vacuum variable capacitor usually consists of cylinders that are mounted inside an evacuated glass enclosure in order to obtain a high rating of breakdown voltage. While adding to higher voltage capacitance, this device reduces the chances of arching in between the different plates.
  • A variable tuning capacitor is usually used in the process of varying the frequency of resonance of a relatively oscillatory circuit.


  • A high voltage variable ceramic capacitor is able to retain and supply a very high amount of energy or electricity that can be also controlled. The retaining capacity of energy along with the rate of flow can be adjusted through the device.

For an average person, a variable capacitor is an uncommon term. Little did they know that without these necessary device, the daily activities would’ve have been a different story.