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 distinguished by high electricalindicators, 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 capacitorsThey are used in the circuits of generators and heterodyne of high stability. Thermocompensating elements are used to restore the temperature. A special group consists of ferro-ceramic capacitors, in which a ferroelectric ceramics is used as a dielectric - a material with a very high permittivity (up to several thousand) in a certain temperature range. These products differ from high-frequency ceramics with a larger capacity for the same size.

The ceramic tubular capacitor (KT-1, KT-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 of the heel 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 CT products are painted,CDS, CD, etc., 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 noticeably - these are heat-compensating capacitors. The orange color indicates that in the case of a change in the temperature regime over a wide range, the capacity of the product will vary 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.

Condenser, trim, ceramic (CPC)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. When rotating, the relative arrangement of the plates, respectively, and the capacitance between them change.

Condenser, trim, ceramic, tubular(CCPT) - the very name indicates that the product in question is in 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 withproduction of the mentioned capacitors, the products were referred to the category of low-capacity devices. 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 declare that they have reached the capacity limit in such capacitors up to 100 microfarads, but, as they assure, this is not the limit.