The Common Role Of Capacitors in Circuits
May 16, 2022
Capacitors are essential components in electronic circuits and are also widely used in power systems. Capacitive element, referred to as capacitor, is a "container" that stores electric charge. According to the international unified regulations, the amount of charge that can be stored when a capacitor is applied with a DC voltage of 1 volt is the capacitance of the capacitor, represented by the letter C. A common unit of capacitance is microfarads (μF).
The functions of capacitors in the circuit mainly include the following 8 points:
1. Play the role of coupling
It refers to the capacitor in the coupling circuit. It is called coupling capacitor when used in AC amplifiers and other capacitive coupling circuits. The front and rear stages are connected through the coupling capacitor, which plays the role of blocking DC and AC.
2. Play the role of filtering
The capacitors used in the filter circuit are called filter capacitors, which are used in power filters and various filter circuits. The filter capacitors can effectively filter out harmful signals in a certain frequency band.
3. Play the role of decoupling
The capacitors used in decoupling circuits are called decoupling capacitors and are used in the DC power supply circuit of multi-stage amplifiers. Decoupling capacitors eliminate harmful low-frequency cross-connections between amplifiers at all levels.
4. Play the role of bypass
Capacitors used in bypass circuits are called bypass capacitors. If a certain frequency band needs to be removed from the signal in the circuit, it is often bypassed with a capacitor. According to the different frequencies of the removed signal, there are full frequency domain (all AC signals) bypass capacitor circuits and high frequency bypass capacitor circuits.
5. Play the role of timing
Refers to the capacitor used in the timing circuit called the timing capacitor. In circuits that need to control the time by charging and discharging the capacitor, the capacitor plays the role of controlling the time constant.
6. Play the role of differentiation and integration
Capacitors used in differential circuits are called differential capacitors. In order to obtain the peak trigger signal in the trigger circuit, a differential capacitor circuit is often used to obtain the peak pulse trigger signal from various types of mainly rectangular pulse signals. Capacitors used in integrating circuits are called integrating capacitors. For example, in the synchronizing separation circuit of TV field scanning, the integrating capacitor circuit is used, and the field synchronizing signal can be taken out from the field composite synchronizing signal.
7. Play the role of compensation
Refers to the capacitor used in the compensation circuit called compensation capacitor, such as reactive power compensation in the power grid. It uses the principle that the current of the capacitor on the line is just the opposite of the inductor current. As long as the number of capacitors connected to the line matches the inductive component of the load, the generated capacitive current can eliminate or reduce the reactive power absorbed by the load into the grid. . In this way, the burden of electrical circuits and transformer equipment can be reduced, and the utilization rate of electrical circuits and transformer equipment can be improved.
8. Play the role of frequency division
It means that the capacitor in the frequency division circuit is called the frequency division capacitor. In the speaker frequency division circuit of the speaker, the tweeter works in the high frequency band through the frequency division capacitor, the intermediate frequency speaker works in the middle frequency band, and the low frequency speaker works in the low frequency band.
