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On the eight basic functions of metal film capacitors
Mar 02, 2019

1.Isolated dc. This is not only the function of the metal film capacitors, but also the basic function of all capacitors, which is to prevent the dc from passing through and let the ac pass through.


2. Coupling. The coupling effect of the metal film capacitor is to act as a connection between two circuits, allowing the ac signal to pass through and be transmitted to the lower circuit. In the circuit, coupling is used as a component to transmit the front signal to the back and, and isolate the front from the influence of the back, so as to make the circuit debugging more simple and the performance more stable.


3. Filtering. Capacitance filter function is very important in the circuit, the capacitor behind the CPU is basically this role. When the capacitor USES the filtering function, the larger the frequency f is, the smaller the impedance Z of the capacitor will be. At low frequencies, capacitance C and impedance Z are relatively large, so useful signals can pass through smoothly. At high frequencies, capacitance C is already small due to impedance Z, which is equivalent to short-circuiting high frequency noise to GND.


4. Bypass: the capacitors used in the bypass circuit are called bypass capacitors. In the circuit, if the signal of a certain frequency band needs to be removed from the signal, the bypass capacitor circuit can be used.


5. Temperature compensation. The temperature compensation function of capacitors is mainly to compensate for the influence of other components' insufficient adaptability to temperature, so as to improve the stability of the circuit.


6. High-frequency vibration elimination: the capacitance used in the high-frequency vibration elimination circuit is called high-frequency vibration elimination capacitance. In the audio negative feedback amplifier, in order to eliminate the high-frequency self-excitation that may appear in the vibration, this kind of capacitor circuit is adopted to eliminate the high-frequency noise that may appear in the amplifier.


7. Neutralization. Capacitors used in neutralizing circuits are called neutralizing capacitors. In radio and intermediate frequency amplifiers, and in television high frequency amplifiers, this neutralizing capacitor circuit is used to eliminate self-excitation.


8. Timing. Capacitors used in timing circuits are called timing capacitors. In the need to charge through the capacitor, discharge time control circuit using timing capacitor circuit, capacitor plays a role in controlling the size of the time constant.

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