Similar to a resistor, it is usually referred to as a capacitor for short, represented by the letter C.

As the name suggests, a capacitor is a “container for storing electric charge.” Although there are many types of capacitors, their basic structure and principles are the same.

Two pieces of metal that are very close together are separated by a substance (solid, gas or liquid) to form a capacitor.

The two pieces of metal are called plates, and the substance in the middle is called the medium. Capacitors are also divided into fixed capacity and variable capacity.

But the common ones are fixed-capacity capacitors, and the most common ones are electrolytic capacitors and ceramic capacitors.

 

Different capacitors have different capacities for storing charge.

It is stipulated that the amount of charge stored when a capacitor is applied with a DC voltage of 1 volt is called the capacitance of the capacitor. The basic unit of capacitance is farad (F).

But in fact, farad is a very uncommon unit, because the capacity of capacitors is often much smaller than 1 farad, commonly used microfarad (μF), nanofarad (nF), picofarad (pF) (picofarad is also called picofarad) )Wait.

Their relationship is: 1 farad (F) = 1000000 microfarads (μF) 1 microfarad (μF) = 1000 nanofarads (nF) = 1000000 picofarads (pF)

 

In electronic circuits, capacitors are used to block direct current through alternating current, and are also used to store and release charge to act as a filter to smooth the output pulse signal.

Small-capacity capacitors are usually used in high-frequency circuits, such as radios, transmitters, and oscillators.

Large-capacity capacitors are often used for filtering and storing charges. And there is another feature. Generally, capacitors above 1μF are electrolytic capacitors, while capacitors below 1μF are mostly ceramic capacitors.

Of course there are others too, such as monolithic capacitors, polyester capacitors, and small-capacity mica capacitors.

Electrolytic capacitors have an aluminum shell filled with electrolyte and lead out two electrodes as positive (+) and negative (-) poles. Unlike other capacitors, they cannot be connected to the wrong polarity in the circuit, while other capacitors are There is no polarity.

 

Connect the two electrodes of the capacitor to the positive and negative poles of the power supply. After a while, even if the power supply is disconnected, there will still be residual voltage between the two pins (after learning a later tutorial, you can use a multimeter to observe), we say capacitors Stored charge.

A voltage is built up between the plates of the capacitor to accumulate electrical energy. This process is called the charging of the capacitor.

There is a certain voltage across the charged capacitor. The process of releasing the charge stored in the capacitor to the circuit is called the discharge of the capacitor.