Capacitors are silver plated

What is a silver mica capacitor?

Silver mica capacitors are high precision, stable and reliable capacitors. They are available in small values, and are mostly used at high frequencies and in cases where low losses (high Q) and low capacitor change over time is desired. Mica has been used as a capacitor dielectric since the mid-19th century.

What is a polarised capacitor?

The simplest form of capacitor consists of two parallel conducting plates, separated by a non-conducting (dielectric) material. The orientation of the capacitor in a circuit depends on the type of dielectric used. A polarised capacitor must be connected so that conventional current enters the capacitor via its positive terminal.

Are polyester capacitors polarised?

The polyester, mica and ceramic types described below are non-polarised, while the electrolytic types are polarised. In polyester capacitors, two strips of polyester film (the dielectric) are wound between two strips of aluminium foil (the conducting plates). Each strip of foil is connected to one of the capacitor's leads.

What are the different types of variable capacitors?

Another type of variable capacitor is the trimmer capacitor, a small variable capacitor used to make fine adjustments to the capacitance of a circuit. The second capacitor illustrated below shows the mica compression type, in which metal foil and mica sheets are compressed to a greater or lesser degree by turning a screw.

Why are silver-mica capacitors used at high frequencies?

Silver-mica capacitors are useful at high frequencies, because of their low resistive and inductive losses and high stability over time. Delved in India, Central Africa and South America, the most commonly used are the muscovite and phlogopite mica.

What is the maximum capacitance a plate can produce?

The maximum capacitance that can be achieved with the plates fully interleaved is in the order of 500 pF for a single unit. Another type of variable capacitor is the trimmer capacitor, a small variable capacitor used to make fine adjustments to the capacitance of a circuit.