Ceramic capacitors: description, types

What is ceramics? In everyday life, so called products made by the method of calcining the mass, mainly clays. In the same technique, ceramic means materials with a similar structure, although there are no clays at all, or it is present in a small amount. These include capacitor ceramics, which are used as dielectric capacitors.

Ceramic Capacitors

Such products are characterized by high electrical performance, small size and low cost. Ceramic capacitors are widely used in the circuits of radio equipment. They come with a constant capacity and trim.

Types of capacitors with a constant capacity

Thermostable ceramic capacitors are used in the circuits of generators and heterodyne high stability. Thermocompensating elements are used to restore the temperature. A special group consists of ferro-ceramic capacitors in which ferroelectric ceramics are used as a dielectric - a material with a very high permittivity (up to several thousand) in a certain temperature range. The products mentioned differ from the high-frequency ceramics with a larger capacity at the same dimensions.

Ceramic tubular capacitor (КТ-1, КТ-2) is a thin-walled tube, the outer and inner surfaces of which are covered with a layer of silver.

The ceramic disk condenser (KD1, KD2) and disk ferro-ceramic models (KDS1, KDS2, KDS3) are a round ceramic plate with an overlay in the form of thin layers of silver.

A ceramic, molded plastic element (KOB1, KOB2, KOB3) is a ceramic cylinder, on the base of which also plates are applied.

Color scale and its meaning

Different colors, in which the products of CT, CD, CD, etc., are painted, indicate the stability of their capacity when the temperature changes. Blue, blue and gray paint is used if the capacitance of the capacitor changes slightly in temperature. Such elements are called thermostable. Red and green colors mean that when the temperature rises, the capacity of the items decreases markedly - they are heat-compensating capacitors. The orange color indicates that if the temperature changes over a wide range, the capacity of the product will change quite strongly (however, at room temperature the capacity remains stable).

Types of ceramic trimmer capacitors

These products are designed to fit (adjust) the parameters of the oscillatory circuits, they are also called semi-variable. Let's briefly review each of them.

The pottery ceramic tuning capacitor consists of a ceramic base (stator) and a ceramic movable disk (rotor). The disk on the axis is attached to the stator, and it can be rotated with a screwdriver. Silver plates, shaped like sectors, are plotted on the plane of both components. The material of the rotor is a dielectric. During rotation, the relative arrangement of the plates, respectively, and the capacitance between them change.

Condenser trimmer ceramic tubular (CPT) - the very name indicates that the product in question has the form of a tube. On its inner surface is also applied a thin silver immobile lining - a metal rod with a screw thread. When rotating (achieved by means of a screwdriver), the capacity changes due to the insertion or withdrawal of the rod from the tube.

Capacity of ceramic capacitors

Another 10-20 years ago, due to the difficulties associated with the production of these capacitors, the products were classified as a low-capacity instrument. More recently, a ceramic capacitor of 1 μF would have surprised no one, but an element at 10 μF was perceived as exotic.

But today, the development of technologies has allowed some manufacturers of radio components to announce the achievement of a capacitance limit in such capacitors up to 100 μF, but, they assure, and this is not the limit.