Electric capacitor. Types of capacitors

In electrical stores, capacitors can most often be seen in the form of a cylinder, inside of which there are many strips of plates and dielectrics.

Capacitor - what is it?

A capacitor is part of an electrical circuit consisting of 2 electrodes that are capable of accumulating, focusing or transmitting current to other devices. Structurally, the electrodes are capacitor plates with opposite charges. In order for the device to work, a dielectric is placed between the plates - an element that prevents the two plates from touching each other.

The definition of condenser comes from the Latin word “condenso”, which means compaction, concentration.

Elements for soldering containers are used to transport, measure, redirect and transmit electricity and signals.

Where are capacitors used?

Every novice radio amateur often asks the question: what is a capacitor for? Beginners do not understand why it is needed and mistakenly believe that it can fully replace a battery or power supply.

All radio devices include capacitors, transistors and resistors. These elements make up a board or an entire module in circuits with static values, which makes it the basis for any electrical appliance, from a small iron to industrial devices.

The most common uses of capacitors are:

1. Filter element for HF and LF interference;
2. Levels sudden surges in alternating current, as well as for static and voltage on the capacitor;
3. Voltage ripple equalizer.

The purpose of the capacitor and its functions are determined by the purposes of use:

1. General purpose. This is a capacitor, the design of which contains only low-voltage elements located on small circuit boards, for example, devices such as a television remote control, radio, kettle, etc.;
2. High voltage. The capacitor in the DC circuit supports high-voltage industrial and technical systems;
3. Pulse. Capacitive generates a sharp voltage surge and supplies it to the receiving panel of the device;
4. Launchers. Used for soldering in those devices that are designed to start, turn on/off devices, for example, a remote control or control unit;
5. Noise suppressing. The capacitor in the AC circuit is used in satellite, television and military equipment.

Types of capacitors

The design of the capacitor is determined by the type of dielectric. It comes in the following types:

1. Liquid. Dielectric in liquid form is rare; this type is mainly used in industry or for radio devices;
2. Vacuum. There is no dielectric in the capacitor, but instead there are plates in a sealed housing;
3. Gaseous. Based on the interaction of chemical reactions and used for the production of refrigeration equipment, production lines and installations;
4. Electrolytic capacitor. The principle is based on the interaction of a metal anode and an electrode (cathode). The oxide layer of the anode is the semiconductor part, as a result of which this type of circuit element is considered the most productive;
5. Organic. The dielectric can be paper, film, etc. It is not able to accumulate, but only slightly level out voltage surges;
6. Combined. This includes metal-paper, paper-film, etc. The efficiency increases if the dielectric contains a metal component;
7. Inorganic. The most common ones are glass and ceramic. Their use is determined by durability and strength;
8. Combined inorganic. Glass-film, as well as glass-enamel, which have excellent leveling properties.

Types of capacitors

The elements of the radio board differ in the type of capacitance change:

1. Permanent. The cells maintain a constant voltage capacity until the end of their shelf life. This type is the most common and universal, as it is suitable for making any type of device;
2. Variables. They have the ability to change the volume of the container when using a rheostat, varicap or when the temperature changes. The mechanical method using a rheostat involves soldering an additional element onto the board, while when using a variconde, only the amount of incoming voltage changes;
3. Trimmers. They are the most flexible type of capacitor, with which you can quickly and efficiently increase the throughput of the system with minimal reconstruction.

Operating principle of a capacitor

Let's look at how a capacitor works when connected to a power source:

1. Charge accumulation. When connected to the network, the current is directed to the electrolytes;
2. Charged particles are distributed on the plate according to their charge: negative ones - into electrons, and positive ones - into ions;
3. The dielectric serves as a barrier between the two plates and prevents particles from mixing.

The capacitance of a capacitor is determined by calculating the ratio of the charge of one conductor to its potential power.

Important! The dielectric is also capable of removing the resulting voltage on the capacitor during operation of the device.

Capacitor Characteristics

The characteristics are conventionally divided into points:

1. The amount of deviation. Before entering the store, each capacitor must undergo a series of tests on the production line. After testing each model, the manufacturer indicates the range of permissible deviations from the original value;
2. Voltage value. Mostly elements with a voltage of 12 or 220 Volts are used, but there are also 5, 50, 110, 380, 660, 1000 and more Volts. In order to avoid capacitor burnout and dielectric breakdown, it is best to purchase an element with a voltage reserve;
3. Permissible temperature. This parameter is very important for small devices operating on a 220 Volt network. As a rule, the higher the voltage, the higher the permissible temperature level for operation. Temperature parameters are measured using an electronic thermometer;
4. Availability of direct or alternating current. Perhaps one of the most important parameters, since the performance of the designed equipment completely depends on it;
5. Number of phases. Depending on the complexity of the device, single-phase or three-phase capacitors can be used. To connect an element directly, a single-phase one is sufficient, but if the board is a “city”, then it is recommended to use a three-phase one, as it distributes the load more smoothly.

What does capacity depend on?

The capacitance of the capacitor depends on the type of dielectric and is indicated on the case, measured in uF or uF. It ranges from 0 to 9,999 pF in picofarads, while in microfarads it ranges from 10,000 pF to 9,999 µF. These characteristics are specified in the state standard GOST 2.702.

Note! The larger the electrolyte capacity, the longer the charging time, and the more charge the device can transfer.

The greater the load or power of the device, the shorter the discharge time. In this case, resistance plays an important role, since the amount of outgoing electrical flow depends on it.

The main part of the capacitor is the dielectric. It has the following number of characteristics that affect the power of the equipment:

1. Insulation resistance. This includes both internal and external insulation made from polymers;
2. Maximum voltage. The dielectric determines how much voltage the capacitor is capable of storing or transmitting;
3. The amount of energy loss. Depends on the configuration of the dielectric and its characteristics. Typically, energy dissipates gradually or in sharp bursts;
4. Capacity level. In order for a capacitor to store a small amount of energy for a short period of time, it needs to maintain a constant volume of capacitance. Most often, it fails precisely because of the inability to pass a given amount of voltage;

Good to know! The abbreviation “AC” located on the element body denotes alternating voltage. The accumulated voltage on the capacitor cannot be used or transmitted - it must be extinguished.

Capacitor Properties

The capacitor acts as:

1. Inductive coil. Let's take the example of a regular light bulb: it will light up only if you connect it directly to an AC source. This leads to the rule that the larger the capacity, the more powerful the luminous flux of the light bulb;
2. Charge storage. Properties allow it to quickly charge and discharge, thereby creating a powerful impulse with low resistance. Used for the production of various types of accelerators, laser systems, electric flashes, etc.;
3. The battery received charge. A powerful element is capable of maintaining the received portion of current for a long time, while it can serve as an adapter for other devices. Compared to a rechargeable battery, a capacitor loses some of its charge over time, and is also not able to accommodate a large amount of electricity, for example, for industrial scale;
4. Charging the electric motor. The connection is made through the third terminal (operating voltage of the capacitor is 380 or 220 Volts). Thanks to the new technology, it has become possible to use a three-phase motor (with a phase rotation of 90 degrees), using a standard network;
5. Compensator devices. It is used in industry to stabilize reactive energy: part of the incoming power is dissolved and adjusted at the output of the capacitor to a certain volume.

Video

Capacitors, like resistors, are among the most numerous elements of radio engineering devices. About some properties of a capacitor- "storage" I have already talked about electric charges. At the same time he said that the capacitance of a capacitor will be greater, the larger the area of ​​​​its plates and the thinner the dielectric layer between them.

The basic unit of electrical capacitance is the farad (abbreviated F, named after the English physicist M. Faraday. However, 1 F - This is a very large capacity. The globe, for example, has a capacitance of less than 1 F. In electrical and radio engineering, a unit of capacitance equal to a millionth of a farad is used, which is called a microfarad (abbreviated μF). There are 1,000,000 microfarads in one farad, i.e. 1 microfarad = 0.000001 F. But this unit of capacitance is often too large. Therefore, there is an even smaller unit of capacitance called the picofarad (abbreviated pF), which is a millionth of a microfarad, i.e. 0.000001 µF; 1 µF = 1,000,000 pF. All capacitors, whether constant or variable, are characterized primarily by their capacitances, expressed in picofarads and microfarads, respectively.

On circuit diagrams, the capacitance of capacitors from 1 to 9999 pF is indicated by integers corresponding to their capacitances in these units without the designation pF, and the capacitance of capacitors from 0.01 μF (10000 pF) and more— in fractions of a microfarad or microfarads without the designation μF. If the capacitance of the capacitor is equal to an integer number of microfarads, then, in contrast to the designation of capacitance in picofarads, a comma and a zero are placed after the last significant digit. Examples of designation of capacitor capacities in the diagrams: C1 = 47 corresponds to 47 pF, C2 = 3300 corresponds to 3300 pF; C3 = 0.47 corresponds to 0.047 µF (47000 pF); C4 = 0.1 corresponds to 0.1 µF; C5 = 20.0 corresponds to 20 µF.

A capacitor in its simplest form consists of two plates separated by a dielectric. If a capacitor is connected to a DC circuit, the current in this circuit will stop. Yes, this is understandable: direct current cannot flow through the insulator, which is the dielectric of the capacitor. Including a capacitor in a DC circuit is equivalent to breaking it (we do not take into account the moment of switching on, when a short-term capacitor charging current appears in the circuit). This is not how a capacitor behaves in an alternating current circuit. Remember: the polarity of the voltage at the terminals of the AC source changes periodically. This means that if you include a capacitor in a circuit powered by such a current source, its plates will be alternately recharged at the frequency of this current. As a result, alternating current will flow in the circuit.

A capacitor, like a resistor and a coil, provides resistance to alternating current, but it is different for currents of different frequencies. It can pass high frequency currents well and at the same time be almost an insulator for low frequency currents. Radio amateurs, for example, sometimes use electrical lighting network wires instead of external antennas, connecting receivers to them through a capacitor with a capacity of 220– 510 pF. Was this capacitor chosen by chance? No, not by chance. A capacitor of such a capacity passes high-frequency currents well, which are necessary for the operation of the receiver, but has great resistance to alternating current with a frequency of 50 Hz flowing in the network. In this case, the capacitor becomes a kind of filter, passing high-frequency current and blocking low-frequency current.

The capacitance of a capacitor to alternating current depends on its capacitance and current frequency: the greater the capacitance of the capacitor and the frequency of the current, the lower its capacitance. This capacitor resistance can be determined with sufficient accuracy using the following simplified formula

RC = 1/6fC
π (more precisely 6.28, sinceπ = 3.14).

where RC is the capacitance of the capacitor, Ohm; f - current frequency, Hz; C is the capacitance of this capacitor, F; digit 6 - value 2 rounded to whole unitsπ (more precisely 6.28, sinceπ = 3.14).

Using this formula, let's find out how a capacitor behaves in relation to alternating currents if we use power wires as an antenna. Let's say that the capacitance of this capacitor is 500 pF (500 pF = 0.0000000005 F). Mains frequency 50 Hz. Let's take 1 MHz (1,000,000 Hz) as the average carrier frequency of the radio station, which corresponds to a wave length of 300 m. What resistance does this capacitor have to the radio frequency?

Rc = = 1/(6·1000000·0.0000000005) ~=300 Ohm.

What about alternating current?

Rc = 1/(6·50·0.0000000005) ~= 7 MOhm.

And here is the result: a capacitor with a capacity of 500 pF provides 20,000 times less resistance to high-frequency current than to low-frequency current. Earnestly? A capacitor of smaller capacity provides even greater resistance to the alternating current of the network.

The capacitance of a capacitor to alternating current decreases with an increase in its capacitance and current frequency, and vice versa, increases with a decrease in its capacitance and current frequency.

The property of a capacitor not to pass direct current and to conduct alternating currents of different frequencies in different ways is used to separate pulsating currents into their components, retain currents of some frequencies and pass currents of other frequencies.

How are constant capacitors constructed?

All capacitors of constant capacity have conductive plates, and between them - ceramics, mica, paper or some other solid dielectric. Based on the type of dielectric used, capacitors are called ceramic, mica, or paper, respectively. The appearance of some ceramic constant capacitors is shown in Fig. 1

Rice. 1. Ceramic constant capacitance capacitors

They use special ceramics as a dielectric, with plates— thin layers of silver-plated metal deposited on the surface of ceramics, and the leads are brass silver-plated wires or strips soldered to the plates. The capacitor housings are covered with enamel on top.

The most common ceramic capacitors are the KDK (Ceramic Disc Capacitor) and KTK (Ceramic Tubular Capacitor) types: For a KTK type capacitor, one plate is applied to the inner and the second to the outer surface of a thin-walled ceramic tube. Sometimes tubular capacitors are placed in sealed porcelain "cases" with metal caps at the ends. These are KGK type capacitors.

Ceramic capacitors have relatively small capacitances - up to several thousand picofarads. They are placed in those circuits in which high-frequency current flows (antenna circuit, oscillatory circuit) for communication between them.

To obtain a capacitor of small size, but with a relatively large capacity, it is made not from two, but from several plates, stacked and separated from each other by a dielectric (Fig. 2). In this case, each pair of adjacent plates forms a capacitor. By connecting these pairs of plates in parallel, a capacitor of significant capacity is obtained.

Rice. 2. Mica capacitors

This is how all capacitors with a mica dielectric are designed. Their plates— The plates are sheets of aluminum foil or layers of silver deposited directly on mica, and the leads are pieces of silver-plated wire. Such capacitors are molded with plastic. These are KSO capacitors. Their name contains a number characterizing the shape and size of the capacitors, for example: KSO-1, KSO-5. The higher the number, the larger the size of the capacitor. Some mica capacitors are produced in ceramic, waterproof cases. They are called SGM type capacitors. The capacitance of mica capacitors ranges from 47 to 50,000 pF (0.05 µF). Like ceramic ones, they are intended for high-frequency circuits, as well as for use as interlocking and for communication between high-frequency circuits.

In paper capacitors (Fig. 3), the dielectric is paraffin-impregnated thin paper, and the plates are foil. Strips of paper together with the covers are rolled into a roll and placed in a cardboard or metal case. The wider and longer the plates, the greater the capacitance of the capacitor.

Rice. 3. Paper and metal-paper capacitors of constant capacity

Paper capacitors are used mainly in low-frequency circuits, as well as for blocking power supplies. There are many types of capacitors with paper dielectric. And all of them have the letter B (Paper) in their designation. Capacitors of the BM type (Small Paper) are enclosed in metal tubes, filled at the ends with a special resin.

KB capacitors have cardboard cylindrical cases. Capacitors of the KBG-I type are placed in porcelain cases with metal end caps connected to plates from which narrow lead petals extend.

Capacitors with a capacity of up to several microfarads are produced in metal cases. These include capacitors of the KBG-MP, KBG-MN, KBGT types. There may be two or three of them in one building.

The dielectric of capacitors of the MBM type (Metal-paper Small-sized) is varnished capacitor paper, and the plates are layers of metal less than a micron thick deposited on one side of the paper. A characteristic feature of capacitors of this type— the ability to self-heal after electrical breakdown of a dielectric.

A special group of constant-capacity capacitors are electrolytic ones (Fig. 4).

Rice. 4. Electrolytic capacitors

In terms of its internal structure, an electrolytic capacitor is somewhat reminiscent of a paper capacitor. It contains two aluminum foil strips. The surface of one of them is covered with a thin layer of oxide. Between the aluminum strips there is a strip of porous paper impregnated with a special thick liquid.— electrolyte. This four-layer strip is rolled up and placed in an aluminum cylindrical cup or cartridge.

The dielectric of the capacitor is an oxide layer. The positive plate (anode) is the tape that has an oxide layer. It is connected to a petal isolated from the body. The second, negative plate (cathode) paper, impregnated with electrolyte through a tape on which there is no oxide layer, is connected to the metal body. Thus, the body is a negative terminal, and the petal isolated from it is the terminal of the positive plate of the electrolytic capacitor. This is how, in particular, capacitors of the KE and K50-3 types are designed. KE-2 capacitors differ from KE type capacitors only in the plastic bushing with thread and nut for mounting on the panel. Aluminum housings of K50-3 capacitors have the shape of a cartridge with a diameter of 4.5– 6 and length 15-20 mm. conclusions— wire Capacitors of type K50-6 are designed similarly. But their electrode terminals (plates) are isolated from the housings.

On circuit diagrams, electrolytic capacitors are depicted in the same way as other capacitors of constant capacitance - with two " dashes, but put a sign near the positive facing« + » .

Electrolytic capacitors have large capacitances— from fractions to several thousand microfarads. They are designed for use in circuits with pulsating currents, such as AC rectifier filters, for coupling between low frequency circuits. In this case, the negative electrode of the capacitor is connected to the negative pole of the circuit, and the positive— with its positive pole. If the switching polarity is not observed, the electrolytic capacitor may fail.

The nominal capacitances of electrolytic capacitors are written on their cases. The actual capacity may be significantly greater than the nominal capacity.

The most important characteristic of any capacitor, in addition to capacitance, is also its rated voltage, i.e. the voltage at which the capacitor can operate for a long time without losing its properties. This voltage depends on the properties and thickness of the dielectric layer of the capacitor. Ceramic, mica, paper and metal-paper capacitors of various types are designed for rated voltages from 150 to 1000 V or more.

Electrolytic capacitors are produced at rated voltages from several volts to 30– 50 V and from 150 to 450 – 500 V. In this regard, they are divided into two groups: low-voltage and high-voltage. Capacitors of the first group are used in circuits with relatively low voltage, and capacitors of the second group— in circuits with relatively high voltage.

When selecting capacitors for your designs, always pay attention to their rated voltages. In a circuit with a voltage lower than the rated one, capacitors can be turned on, but in a circuit with a voltage higher than the rated voltage, they cannot be turned on. If there is a voltage on the capacitor plates that exceeds its rated voltage, the dielectric will break through. A broken capacitor is unusable.

Now about variable capacitors.

The structure of the simplest variable capacitor is shown in Fig. 5. One of its lining - the stator is stationary. Second rotor— attached to the axle. When the axis rotates, the overlap area of ​​the plates, and with it the capacitance of the capacitor, changes.

Rice. 5. The simplest variable capacitor

Variable capacitors used in tuned oscillating circuits of receivers consist of two groups of plates (Fig. 6, a) made of sheet aluminum or brass. The rotor plates are connected by an axis. The stator plates are also connected and isolated from the rotor. When the axis rotates, the plates of the stator group gradually enter the air gaps between the plates of the rotor group, causing the capacitance of the capacitor to smoothly change. When the rotor plates are completely removed from the gaps between the stator plates, the capacitance of the capacitor is smallest; it is called the initial capacitance of the capacitor. When the rotor plates are fully inserted between the stator plates, the capacitance of the capacitor will be greatest, i.e., maximum for a given capacitor. The maximum capacitance of the capacitor will be greater, the more plates it contains and the smaller the distance between the moving and stationary plates.

In the capacitors shown in Fig. 5 and 6, a, the dielectric is air. In small-sized variable capacitors (Fig. 6, b), the dielectric can be paper, plastic films, or ceramics. Such capacitors are called solid dielectric variable capacitors. With smaller dimensions than air dielectric capacitors, they can have significant maximum capacitances. It is these capacitors that are used to tune the oscillatory circuits of small-sized transistor receivers.

Rice. 7. One of the designs of a block of variable capacitors

Single capacitors and blocks of variable capacitors with an air dielectric require careful handling. Even slight bending or other damage to the plates leads to a short circuit between them. Correction of the same capacitor plates- it's a complicated matter.

Capacitors with a solid dielectric also include tuning capacitors, which are a type of variable capacitor. Most often, such capacitors are used to tune circuits to resonance, which is why they are called tuning capacitors. The designs of the most common tuning capacitors are shown in Fig. 8. Each of them consists of a relatively massive ceramic base and a thin ceramic disk. On the surface of the base (under the disk) and on the disk, metal layers are applied in the form of sectors, which are the plates of the capacitor. When the disk rotates around its axis, the overlap area of ​​the sectors-plates changes, and the capacitance of the capacitor changes.

The capacity of tuning capacitors is indicated on their cases in the form of a fractional number, where the numerator is the smallest and the denominator is the largest capacity of the given capacitor. If, for example, 6/30 is indicated on a capacitor, this means that its smallest capacitance is 6 pF, and its largest is 30 pF. Trimmer capacitors usually have the smallest capacitance 2 – 5 pF, and the highest up to 100– 150 pF. Some of them, such as KPK-2, can be used as variable capacitors to configure simple single-circuit receivers.

Capacitors, like resistors, can be connected in parallel or in series. Connecting capacitors is most often resorted to in cases where there is no capacitor of the required value at hand, but there are others from which the required capacitance can be made. If you connect capacitors in parallel (Fig. 8, a), then their total capacitance will be equal to the sum of the capacitances of all connected capacitors, i.e.

Commun = C1 + C2 + C3, etc.

So, for example, if C1 = 33 pF and C2 = 47 pF, then the total capacitance of these two capacitors will be: Total = 33 + 47 = 80 pF. When capacitors are connected in series (Fig. 8, b), their total capacitance is always less than the smallest capacitance included in the chain. It is calculated by the formula

Comm = C1 · C2/(C1 + C2)

For example, let's say that C1 = 220 pF and C2 = 330 pF; then Total = 220 · 330/(220 + 330) = 132 pF. When two capacitors of the same capacitance are connected in series, their total capacitance will be half the capacitance of each of them.

Rice. 8. Parallel (a) and series (b) connections of capacitors

According to another version (as we know, the plausibility of historical facts of very high frequencies is quite difficult to prove), Muschenbroek specifically tried to “charge” the water in the jar. At that time, scientists and researchers still believed that electricity was a kind of liquid that was found in any charged body or object. So, the scientist deliberately lowered the electrode of the electric machine into the water, and then, taking the jar with one hand and accidentally touching the electrode with the other, he again felt a powerful electric shock. And since the experiment was carried out in the city of Leiden, this jar, a prototype of a capacitor, began to be called the Leiden jar.

There is another version of the event. Around the same time - in 1745 rector of the cathedral in Pomerania - German clergyman Ewald Jugen von Kleist tried to conduct a scientific experiment in order to “charge” holy water with electricity and thereby make it even more useful. He also used an electric machine, which were quite popular at the time. True, he did not put the electrode itself into the jar, but used a metal nail as a conductor. Having accidentally touched a nail, I also felt the full force of electricity.

In this form, the capacitor existed for the following 200 years. Scientists and researchers modified it a little - they coated the jar inside and out with metal, removed the water, and used it for various experiments in the field of studying electricity.

By the way, the word “capacitance”, which is now used to denote the value of modern capacitors, is a tribute to the past. After all, initially this element was a glass vessel (jar), which had a certain volume or capacity. By the way, Leyden jars were of different volumes and the larger, the more area the electrodes covered them from the inside and outside. , as is known, even from a school physics course, the larger the area of ​​the capacitor’s electrodes, the greater its capacity.

A capacitor is a common two-pole device used in various electrical circuits. It has a constant or variable capacity and is characterized by low conductivity; it is capable of accumulating a charge of electric current and transmitting it to other elements in the electrical circuit.
The simplest examples consist of two plate electrodes separated by a dielectric and accumulating opposite charges. In practical conditions, we use capacitors with a large number of plates separated by a dielectric.

The capacitor starts charging when the electronic device is connected to the network. When the device is connected, there is a lot of free space on the electrodes of the capacitor, therefore the electric current entering the circuit is of the greatest magnitude. As it is filled, the electric current will decrease and disappear completely when the device’s capacity is completely filled.

In the process of receiving an electric current charge, electrons (particles with a negative charge) are collected on one plate, and ions (particles with a positive charge) are collected on the other. The separator between positively and negatively charged particles is a dielectric, which can be used in various materials.

When an electrical device is connected to a power source, the voltage in the electrical circuit is zero. As the containers are filled, the voltage in the circuit increases and reaches a value equal to the level at the current source.

When the electrical circuit is disconnected from the power source and a load is connected, the capacitor stops receiving charge and transfers the accumulated current to other elements. The load forms a circuit between its plates, so when the power is turned off, positively charged particles will begin to move towards the ions.

The initial current in the circuit when a load is connected will be equal to the voltage across the negatively charged particles divided by the value of the load resistance. In the absence of power, the capacitor will begin to lose charge and as the charge in the capacitors decreases, the voltage level and current in the circuit will decrease. This process will only complete when there is no charge left in the device.

The figure above shows the design of a paper capacitor:
a) winding the section;
b) the device itself.
On this picture:

1. Paper;
2. Foil;
3. Glass insulator;
4. Lid;
5. Frame;
6. Cardboard gasket;
7. Wrapping;
8. Sections.

Capacitor capacity is considered its most important characteristic; the time it takes to fully charge the device when connecting the device to a source of electric current directly depends on it. The discharge time of the device also depends on the capacity, as well as on the load size. The higher the resistance R, the faster the capacitor will empty.

As an example of the operation of a capacitor, consider the operation of an analog transmitter or radio receiver. When the device is connected to the network, the capacitors connected to the inductor will begin to accumulate charge, electrodes will collect on some plates, and ions on others. After the capacity is fully charged, the device will begin to discharge. A complete loss of charge will lead to the start of charging, but in the opposite direction, that is, the plates that had a positive charge this time will receive a negative charge and vice versa.

Purpose and use of capacitors

Currently, they are used in almost all radio engineering and various electronic circuits.
In an alternating current circuit they can act as capacitance. For example, when you connect a capacitor and a light bulb to a battery (direct current), the light bulb will not light. If you connect such a circuit to an alternating current source, the light bulb will glow, and the intensity of the light will directly depend on the value of the capacitance of the capacitor used. Thanks to these features, they are now widely used in circuits as filters that suppress high-frequency and low-frequency interference.

Capacitors are also used in various electromagnetic accelerators, photo flashes and lasers due to their ability to store a large electrical charge and quickly transfer it to other low-resistance network elements, thereby creating a powerful pulse.

In secondary power supplies they are used to smooth out ripples during voltage rectification.

The ability to retain a charge for a long time makes it possible to use them for storing information.

Using a resistor or current generator in a circuit with a capacitor allows you to increase the charging and discharging time of the device’s capacitance, so these circuits can be used to create timing circuits that do not have high requirements for temporal stability.

In various electrical equipment and in higher harmonic filters, this element is used to compensate reactive power.