The so-called capacitor is the electronic component that holds and releases the charge. The basic working principle of the capacitor is charging and discharging, of course, rectification, oscillation and other functions. In addition, the structure of the capacitor is very simple, mainly composed of two positive and negative electrodes and an insulating medium sandwiched between them, so the type of capacitor is mainly determined by the electrode and the insulating medium. There are many uses for capacitors, mainly as follows:

1. DC blocking: The role is to prevent DC from passing and let the AC pass.

2. Bypass (decoupling): Provides a low impedance path for some of the parallel components in the AC circuit.

3. Coupling: as a connection between two circuits, allowing AC signals to pass through and transmit to the next level of electricity

4. Filtering: This is very important for DIY, the capacitance on the graphics card is basically this effect.

5. Temperature compensation: compensates for the influence of other components on the temperature, and compensates to improve the stability of the circuit.

6. Timing: Capacitors are used in conjunction with resistors to determine the time constant of the circuit.

7. Tuning: System tuning of frequency-dependent circuits such as cell phones, radios, and televisions.

8. Rectification: Turns the semi-closed conductor switching element on or off at a predetermined time.

9. Energy storage: Stores electrical energy for release when necessary. For example camera flash, heating equipment, etc. (The energy storage level of some capacitors is now close to the level of lithium batteries, and the energy stored in one capacitor can be used by one mobile phone for one day.