Is there a positive or negative AC capacitor? How capacitors distinguish between positive and negati

Non-polar capacitors, that is, there is no need to distinguish between positive and negative electrodes, and they can be used casually, including monolithic capacitors, ceramic capacitors, metal film capacitors (this is a cylinder, but it is a non-polar capacitor), mica capacitors, paper oil immersion capacitors, etc.;

There are polar capacitors, and positive and negative electrodes must be distinguished, mainly referring to electrolytic capacitors, including aluminum electrolytic capacitors.

Niobium electrolytic capacitors, tantalum electrolytic capacitors, etc., these capacitors are also made into cylinders and patches, so they cannot be identified by the judgment method of friends upstairs. In addition, solid-state capacitors and supercapacitors.

It is also a part of the electrolytic capacitor, so it is also polar.

Here are a few correct ways to identify the positive and negative electrodes of an electrolytic capacitor:

1. Identification of positive and negative electrodes of bolt-type electrolytic capacitors. Bolt-type aluminum electrolytic capacitors have clear positive and negative grade marks on the bushing, and the positive electrode is represented by "+" and the negative electrode is represented by "-". Most of the bolt capacitors are on the terminals on the cover plate.

There will be a "+" logo engraved next to it.

2. Distinguish between the positive and negative electrodes of aluminum electrolytic capacitors of solder lugs. Solder sheet aluminum electrolytic capacitors are also known as horn capacitors, and at present, all manufacturers use the "negative electrode identification", that is, the solder pin corresponding to the "-" identification of the sleeve is the negative electrode. The positive and negative electrodes of electrolytic capacitors are also distinguished on the cover plate, most of which are identified by "embossing" the negative electrode, and some electrolytic capacitor manufacturers directly print the "+" logo on the rivet.

3. Identification method of positive and negative electrodes of electrolytic capacitors in lead structure. The electrolytic capacitor of the lead structure is also marked as a "negative electrode", that is, the lead corresponding to the "-" identification of the sleeve is the negative electrode. There is also the identification of the length of the lead, the long lead is the positive pole, and the short lead is the negative pole.

4. Identification method of positive and negative electrodes of chip aluminum electrolytic capacitors. Chip aluminum electrolytic capacitors are also called chip aluminum electrolytic capacitors, chip aluminum electrolytic capacitors are without bushing, so the bottom of the aluminum shell is printed with capacity, voltage, positive and negative electrodes and other relevant information, as shown in the figure below, half of the black is printed as the negative electrode.

There should be no positive or negative difference between AC capacitors, only capacitance and withstand voltage, volume and frequency regulations.

The 6UF 450V AC capacitor is a non-polarized capacitor. The access circuit does not need to be polarized.

How to distinguish between positive and negative electrodes of capacitors is as follows:

1. The electrolytic capacitor distinguishes the positive and negative poles, and the side end pin of the capacitor sleeve with white silver edge and a word mark is the negative pole of the capacitor; The new capacitor pin is long with a positive end of the capacitor.

2. The bolt electrolytic capacitor distinguishes the positive and negative electrodes, and the ports with + marks on both sides of the white silver edge of the capacitor sleeve are the positive electrodes of the capacitors; The capacitor sleeve has a white silver edge and a word mark on the port, which is the negative electrode of the electric carrying land capacitance.

3. The chip aluminum electrolytic capacitor distinguishes the positive and negative electrodes, and the corresponding port of the black and gray semicircle at the top of the capacitor sleeve cylinder is the negative electrode of the capacitor, and the other port is the positive electrode of the capacitor.

4. Tantalum capacitors are distinguished from positive and negative poles, and one end of the capacitor body is marked by a word at both ends of the capacitor is the negative pole of the capacitor, and the other section is the positive pole of the capacitor. There is no positive and negative distinction between ceramic capacitors and CBB capacitors, so remember to check the withstand voltage range of the capacitor before use.

Classification of capacitance:

1. Bypass. A bypass capacitor is an energy storage device that provides energy to the local device, which can homogenize the output of the regulator and reduce the load demand. Like a small, flushable rechargeable battery, a bypass capacitor can be charged and discharged into the device.

In order to minimize the impedance, the bypass capacitor should be as close as possible to the power supply pin and ground pin of the load device.

2. Decoupling. Decoupling, also known as decoupling. In terms of circuits, it is always possible to distinguish between the source of the drive and the load being driven.

If the load capacitance is relatively large, the driving circuit should charge and discharge the capacitor in order to complete the signal jump, and when the rising edge is relatively steep, the current is relatively large, so that the driving current will absorb a large power supply current.

Due to the inductance in the circuit, the resistance will produce **, and this current is actually a kind of noise relative to the normal situation, which will affect the normal operation of the pre-stage, which is called "coupling". The decoupling capacitor plays the role of a "battery" to meet the change of the current of the driving circuit and avoid coupling interference between them.

3. Filtering. Theoretically (i.e., assuming the capacitor is pure capacitance), the larger the capacitance, the smaller the impedance, and the higher the frequency of passage. However, in fact, most capacitors over 1 F are electrolytic capacitors, which have a large inductance component, so the impedance increases when the frequency is high.

Sometimes you will see a large capacitance electrolytic capacitor connected to a small capacitor in parallel, then the large capacitor filters the low frequency, and the small capacitor filters the high frequency.

Capacitors have positive and negative poles.

Ordinary electrolytic capacitors: Identification method 1: The one marked with "--" on the shell of the capacitor is the negative pole, and the other pole is the positive pole.

The color of the negative electrode is generally gray-white, and the end of the positive electrode is mostly black. Identification method 2: In the newly purchased capacitors, among the unused capacitors, the two pins are long to represent the positive pole of the capacitor, and the short one is the negative pole of the capacitor.

It should be noted that the capacitance is divided into positive and negative polar capacitance, which is commonly referred to as electrolytic capacitance.

Capacitor, as the name suggests, is a container of electricity, in the circuit, mainly plays the role of voltage stabilization, isolation, filtering, decoupling, energy storage, etc., in the transformer, it is mainly voltage stabilization, and some power supplies use electrode capacitors, which play a filtering role.

Whether the capacitor is divided into positive and negative poles is divided into two cases:

1. Non-polar capacitors, that is, there is no need to distinguish between positive and negative electrodes, and they can be used casually, including multilayer capacitors, ceramic capacitors, metal film capacitors (this is a cylinder, but it is a non-polar capacitor), mica capacitors, paper oil immersion capacitors, etc.;

2. There are polar capacitors, and positive and negative electrodes must be distinguished, mainly referring to electrolytic capacitors, including aluminum electrolytic capacitors, niobium electrolytic capacitors, tantalum electrolytic capacitors, etc., these capacitors are also made into cylinders, and there are also patches, in addition, solid capacitors and supercapacitors are also part of electrolytic capacitors, so they are also polar.

Capacitance, also known as "capacitance", refers to the amount of charge stored at a given potential difference, denoted as c, and the SI unit is farad (f). Generally speaking, the charge will move under force in the electric field, and when there is a medium between the conductors, it hinders the movement of the charge and makes the charge accumulate on the conductor, resulting in the accumulation and storage of charge, and the amount of stored charge is called capacitance. Capacitance refers to the ability to hold an electric charge.

Any electrostatic field is made up of many capacitors, and where there is an electrostatic field, there is a capacitance, and the capacitance is described in terms of an electrostatic field. It is generally believed that an isolated conductor and infinity constitute a capacitance, and the grounding of the conductor is equivalent to being connected to infinity and connected with the earth as a whole.

Generally, electrolytic capacitors need to distinguish between positive and negative poles, and other capacitors do not.

There are two types. One is the electrodeless capacitance, which does not distinguish between positive and negative.

There is also a pole capacitor, which is divided into positive and negative poles, such as electrolytic capacitor, which is divided into positive and negative electrodes, and cannot be reversed. If it's reversed, it will explode.

Some of the electric Zen disfigurements have positive and negative poles, and some do not. Ordinary common electrolytic capacitors, two feet are not one long. The long one is the positive electrode, and the short one is the negative one.

SMD tantalum electrolytic capacitors with a positive electrode on one side of the ribbon. Others, such as hermaphroditic electrolytic capacitors, polyester capacitors, ceramic capacitors, variable and trimmer capacitors, are not positive or negative.

Capacitor role:

1. Coupling: The capacitance used in the coupling circuit is called the coupling capacitance.

This type of capacitive circuit is widely used in resistor-capacitive coupling amplifiers and other capacitive coupling circuits to play a role in direct flow AC.

2. Filtering: used in filter circuits.

The capacitor in is called the filter capacitor.

This capacitor circuit is used in power supply filtering and various filter circuits, and the filter capacitor removes the signal in a certain frequency band from the total signal.

3. Decoupling: The capacitor used in the decoupling circuit is called the decoupling capacitor, which is used in the DC voltage supply circuit of the multi-stage amplifier, and the decoupling capacitor eliminates the harmful low-frequency cross-connection between each stage of the amplifier.

On the surface of a general pin with three pins, there are surface positive and negative electrodes.

If not, it is generally a non-polarized capacitor.