【DESCRIPTION】：In the power supply circuit, the rectifier circuit changes AC into pulsating DC, and a large capacity electrolytic capacitor is connected after the rectifier circuit. By using its charge discharge characteristics, the pulsating DC voltage after rectification becomes relatively stable DC voltage. In practice, in order to prevent the supply voltage of each part of the circuit from changing due to the load change, the output end of the power supply and the power input end of the load are generally connected with tens to hundreds of micro capacitors

Because the large capacity electrolytic capacitor usually has a certain inductance, which can not effectively filter out the high frequency and pulse interference signals, a capacitor with the capacity of 0.001-0.lpf is connected in parallel at both ends of the capacitor to filter out the high frequency and pulse interference. Coupling effect: in the process of low-frequency signal transmission and amplification, in order to prevent the static working points of the front and rear circuits from affecting each other, the capacitor coupling is often used In order to prevent the loss of low frequency components in the signal, electrolytic capacitors with larger capacity are generally used.