How to determine the polarity of electrolytic capacitors, where is the plus and minus? How to correctly determine the polarity of a capacitor - step-by-step instructions Indication of the minus of a capacitor on a printed circuit board

An electrolytic capacitor is a strange electronic component that combines the properties of a passive element and semiconductor device. Unlike an ordinary capacitor, it is a polar element.

Instructions

1. For domestically produced electrolytic capacitors, the ends of which are located radially or axially, to determine the polarity, find the plus sign located on the housing. The outcome closest to which it is placed is positive. Some old Czech-made capacitors are marked in a similar way.

2. Capacitors of coaxial design, in which the housing is designed to be connected to the chassis; usually prepared for use in anode voltage filters of devices made on lamps. Because it is correct, in most cases the negative plate is placed on the body, and the positive plate is placed on the central contact. But there may be exceptions to this rule; therefore, if in doubt, look for markings on the device body (plus or minus designation) or, if there is none, check the polarity using the method described below.

3. A non-standard case appears when checking electrolytic capacitors of type K50-16. Such a device has a plastic bottom, and the polarity marking is placed directly on it. Occasionally, the minus and plus signs are arranged in such a way that the totals pass directly through their centers.

4. An outdated type capacitor could be mistaken for a diode by the uninitiated. Typically, the polarity on its body is indicated by the method described in step 1. If there is no marking, know that the result, located on the side of the body thickening, is connected to the correct lining. Do not disassemble such capacitors under any circumstances - they contain toxic substances!

5. The polarity of modern imported electrolytic capacitors, regardless of their design, can be determined by the strip located next to the negative result. It is applied in a color contrasting to the color of the body, and is intermittent, i.e. seems to consist of minuses.

6. To determine the polarity of an unmarked capacitor, assemble a circuit consisting of a continuous voltage source of several volts, a one-kilo-ohm resistor and a microammeter, combined in steps. Completely discharge the device, and only then connect it to this circuit. Once fully charged, read the device readings. After this, disconnect the capacitor from the circuit, completely discharge it again, plug it into the circuit, wait until it is fully charged and read the new readings. Compare them with the previous ones. When connected in positive polarity, the loss is noticeably less.

Automotive stores sell lead-acid batteries of direct polarity (all domestic cars are equipped with them) and reverse polarity (installed on some foreign-made cars). Before buying a battery, you need to correctly identify it polarity .

You will need

Voltmeter

Instructions

1. The service life of every battery is limited and, as usual, is no more than five years. Having worked for the allotted time, the time inevitably comes to replace the power unit. And if the task of owners of domestically produced cars is to choose a battery of the appropriate capacity and give preference to a certain brand, then owners of imported cars need to find out before purchasing polarity battery

2. To achieve this task, the battery is removed from the battery socket and positioned in such a way that when visually inspected from above, its terminals must be at the bottom. Please note that one of them is slightly thinner than the other (it is negative).

3. If the negative terminal is located on the left (bottom) of the battery, then the battery has reverse polarity.

4. In cases where the thinner terminal on the right is larger, the battery has straight polarity.

5. To finally make sure that the polarity of the battery is determined correctly, attach a voltmeter to it. In this case, the scarlet probe of the device removes voltage from the thick terminal, and the black probe from the thin one. The reading on the scale without the minus sign confirms the battery parameters being studied.

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Pay attention!
Installing a battery with the wrong polarity into a car is scary because you won't be able to connect cables to its terminals.

Any diode changes its conductivity depending on the polarity of the voltage applied to it. The location of the electrodes on its body is not indicated invariably. If there is no corresponding marking, you can determine which electrode is connected to which output on your own.

Instructions

1. First of all, determine polarity voltage on the probes of the measuring device you are using. If it is universal, set it to ohmmeter mode. Take any diode on the body of which the location of the electrodes is indicated. In this designation, the “triangle” corresponds to the anode, and the “stripe” corresponds to the cathode. Try connecting the probes to the diode in different polarities. If it conducts current, then the probe with the correct potential is connected to the anode, and with a negative potential - to the cathode. Remember that polarity in the resistance measurement mode on pointer instruments may differ from that indicated for the voltage and current measurement modes. But on digital devices it is traditionally identical in all modes, but it still doesn’t hurt to check.

2. If you are testing a directly heated vacuum diode, first of all, find that it has a combination of pins between which the current passes independently of the polarity of the connection of the measuring device. This is the filament, which is also the cathode. Use the reference book to find the rated filament voltage diode. Apply a continuous voltage of the appropriate magnitude to the filament. Connect the probe of the device on which the negative potential is located to one of the pins of the filament, and with the positive probe touch the remaining ends of the lamp in turn. Having found a pin that, when touched with a probe, displays a resistance less than infinity, conclude that this is the anode. Directly heated strong vacuum diodes (kenotrons) can have two anodes.

3. At the vacuum diode with indirect heating, the heater is isolated from the cathode. Having found it, apply alternating voltage to it, the effective value of which is equal to that indicated in the reference book. After this, among the other results, find two of them, between which current flows at a certain polarity. The one to which the probe with a positive potential is connected is the anode, the opposite one is the cathode. Remember that many indirectly heated vacuum diodes have two anodes, and some have two cathodes.

4. A semiconductor diode each has two outputs. Accordingly, everyone can connect the device to it using two methods. Find the arrangement of the element in which current passes through it. A probe with a positive potential will be connected to the anode, and a probe with a negative potential will be connected to the cathode.

At first glance, indicate on the speaker polarity It makes no sense that alternating voltage is applied to it. But when there are several dynamic heads in the speaker system, they need to be turned on in phase. It is customary to designate the following heads on the results: polarity, at which the diffuser moves forward.

Instructions

1. Make a special probe to test the speakers. To do this, take a regular pocket flashlight based on an incandescent lamp. Remove the switch from it, and instead of the latter, connect two probes. They must strictly have insulated handles, so that at the moment the voltage is turned off, a self-induction voltage appears on the head outputs. Check polarity voltage on the probes using a control voltmeter. Label them accordingly. Make sure that if the probes are shorted, the lamp lights up.

2. Unplug the amplifier and each stereo system (including the outlet). Disconnect both ends of the dynamic head from the rest of the speaker system circuits. Connect the probes to the ends of the head without touching either the ends or the metal parts of the probes. IN at the moment keep an observant eye on the diffuser. If it moves outward when connected, and inward when disconnected, polarity positive. If it is tracked the opposite picture, change polarity connecting the probes, then repeat the check. After this, mark on the dynamic head frame with a permanent felt-tip pen polarity, corresponding to the polarity of connecting the probes.

3. Carry out a similar operation for the remaining speakers within one speaker system. Regardless of how they are connected (directly or through a crossover), connect them in phase so that the red contact on the rear wall of the speaker corresponds to the positive results of the heads.

4. Also check and, if necessary, redo the second one. sound system. After closing the cabinets of both speakers, check whether they are correctly connected to the amplifier. The cable used to make this connection has special red marks. In all cases, connect the conductor with a mark to the red terminal, and the conductor without a mark to the black one.

5. Turn on the stereo complex. Compare its sound with the one that took place before the alteration.

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It would seem, why indicate the polarity on the speaker of a stereo system? It is supplied with alternating voltage. However, if there are several acoustic heads in the system, they must be turned on in phase. The results of one or the other head indicate the polarity value at which the diffuser moves in the forward direction.

You will need

– pocket flashlight with incandescent lamp;
– probes with insulated handles;
– indelible marker;
– voltmeter.

Instructions

1. To determine the polarity of the speaker, make a probe device. Take an ordinary pocket flashlight with an incandescent lamp. Disconnect the switch from it, instead of which you will need to connect two probes. The probes must have insulated handles, since when the voltage is turned off, a self-induction voltage appears at the head ends.

2. With the support of a test voltmeter, check the polarity on the probes, and then apply the appropriate markings to the probes. When the probes close, the lamp should light.

3. Turn off the amplifier and the entire speaker system, and unplug the cord from the outlet. After this, disconnect the results of the dynamic head from the rest of the system circuits. Next, connect both probes to the results of the head, avoiding touching the results and the metal parts of the probes themselves. And look at the diffuser carefully. If it moves outward when connected, and inward when disconnected, then the polarity is positive. If the opposite picture is observed, it is necessary to change the polarity of connecting the probes, and then repeat the test.

4. On the head frame, mark the polarity, preferably with a permanent marker, which corresponds to the polarity of connecting the probes.

5. Do the same operations for the remaining speakers of the speaker system. And it doesn’t matter whether they are connected through a crossover or directly, it is necessary to connect them in phase so that the positive results of the heads correspond to the red contact on the back wall of the speaker itself.

6. Check and modify, if necessary, the second speaker system. Check by closing the housings of the 2 speakers whether their connection to the amplifier is positive. You can mark the cable making such a connection with red marks. In any case, the conductor with the mark should be connected to the red terminal, and the one without the mark should be connected to the black terminal.

7. Turn on the stereo system and compare the sound it makes now with the sound it made before your intervention.

Physicians and psychophysiologists long ago drew attention to the fact that one color or another has an identical effect on all people. For example, scarlet color has a stimulating effect, purple disturbs, blue calms, and green creates a feeling of stability in life.

The most famous expert, the one who studied the impact of colors on people's state of mind, is Max Luscher. He identified four psychotypes of people, based on their color preferences.

Color Personality Types

Red psychotype

People who prefer red are very energetic, they can be compared to an “indestructible motor”. They, as usual, are constantly excited and love this state. As a result of stress, they often experience nervous exhaustion and irritation.

Yellow psychotype

For people of this type, the most important thing is their personal will and the likelihood of self-realization. They love experiments and are not afraid of changes in life. Because of their autonomy, they often feel unsatisfactorily loved and lost.

Blue Psychotype

For these people, the most important thing in life is a peaceful pace of life; they love peace and tranquility. Because they choose to live a “smooth existence” without surprises or unplanned actions, these people often feel sad and alienated when they are around the people who love them.

Green psychotype

People of this temperament love to control the situation and themselves. They calculate the development of events in advance, know what they want to get and what they are willing to give for it. Spontaneity is not one of their qualities. For these people, it is important how they look in the eyes of others and they will take advantage of every opportunity in order to increase their rank.

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Pay attention!
Completely discharge the capacitor before checking and touching its results. When assembling or repairing the structure, always install the device only in the correct polarity; on the contrary, it may break.

Symptoms when capacitors fail are varied. These include freezes and blue screens and simply the computer’s reluctance to turn on. Usually one comes to the conclusion about a hardware problem after installing a “clean” system and installing “native” drivers on it. If freezes and BSODs are observed on a bare system with the correct drivers, we check the hardware.

Another reason for freezes is the failure of elements on the motherboard. Perhaps the most common failures are capacitors.

The breakdown can be easily identified by swollen caps of the capacitors. The top caps of the capacitors are made with a cross-shaped “notch” precisely so that it is easy to identify a non-working capacitor. Capacitors can fail for several reasons. The most common is a low-quality batch. Simply put, it’s a factory defect. Such capacitors will last for about two or three years and then “leak”. The second reason is time. With age, the electrolyte in them dries out, and the capacity decreases. The third reason is overheating. If the capacitor is located near a hot processor, the risk of its failure increases.

Where do we start?

Of course - by turning off the computer from the network. Remember - we perform all manipulations only with the equipment turned off. In this case, it is advisable to disconnect not only the power cable from the system unit, but also all other wires and cables. Power can come from the monitor via a VGA cable; the network card can also be powered by active network equipment.

Remove the cover from the system unit (the left one when looking at the unit from the front). The system (motherboard) board must be unscrewed from the case. We remove all expansion cards, unscrew all the fastening screws that secure the motherboard to the wall. Disconnect the power cables from the power supply. Disconnect the wiring harness going to the front panel of the case. Just in case, sketch out the connection of all wiring to the board. The processor can not be removed from the board.

We find damaged capacitors. We carefully look at the markings. We need to know the capacitance and operating voltage. For example, 1000mF, 6.3V. We run to the nearest electronics store and buy capacitors with the same ratings. Please note that capacitors with a maximum operating temperature of 105 degrees are installed in computer boards. Such capacitors are called “low-impedance” or you can simply say in a store “I need computer capacitors.” The sellers are aware. So, the capacitors have been purchased. By the way, take a thing or two in reserve. If something goes wrong, there will be something to replace it with. Or another faulty one will be discovered. Or it will be left for later.

Soldering old capacitors

It's time to turn on the soldering iron. Please note that elements on modern boards are soldered with lead-free solder, which has a melting point higher than the solder we are familiar with. The soldering iron will need to be heated to 300 degrees (approximately).

We take the payment in hand. It is advisable to ground yourself and have a soldering iron with a grounded tip. Statics is an insidious thing.

We take the capacitor with one hand and use a soldering iron on the other hand to heat the solder point of one leg of the capacitor on the other side of the board. The condenser can be rocked from side to side to move the leg. Solder one leg. We warm up the second one. They pulled out the capacitor. We repeat the procedures for the remaining damaged capacitors. Make sure that when the legs heat up, the soldering iron does not slip and remove small elements from the motherboard. Take your time.

Preparing landing sites

After all the diseased capacitors have been soldered off, you need to take care of the mounting holes for the healthy ones. For such purposes, a special solder suction is usually used. But most likely you don’t have one, so take a needle and carefully expand the holes on both sides. The solder is quite soft and should yield. Don’t overdo it; if you take an awl, you can break the board. The motherboard is multi-layered and a small crack can damage it forever.

Installing new elements

We insert all the capacitors into their places.

Observe polarity. On capacitors, the negative leg is usually marked with a strip on the body. In addition, the minus leg is shorter, the plus leg is longer. The board also has a polarity marking. The minus half is indicated by a white semicircle.

ATTENTION! On some boards (rarely) the polarity is reversed and the semicircle indicates “plus”. Before desoldering old elements, look at the polarity and markings.

The capacitors are inserted, we turn the board over and bend the legs of the capacitors so that they do not fall out.

Soldering

We have come to the most important stage - soldering. Without biting off the legs, place the soldering iron tip directly to the board near the leg. We bring the solder wire to the capacitor leg and lightly touch the soldering iron with the wire. The solder immediately melts and drips down the leg onto the seat. With proper skill it turns out beautifully and quickly. Solder all the legs.

Cleaning up

We take wire cutters and bite off the legs of the capacitors. Don't leave long legs sticking out. They can reach the walls of the case and something will definitely burn. Take care of your eyes! The legs usually fly off from the nippers in any direction. They may get in the eye. It is better to use the nippers with one hand and hold the leg being bitten off with the other hand.

Assembly

As they say, reassemble in reverse order. We first connect all the wiring from the front panel harness to the motherboard. Then wire from the power supply, USB tails, power to the case fans. We screw the board to the wall. We insert expansion cards (video, network, etc.). Connect the power and turn it on.

It works - close the case cover and enjoy.

They are the second most common and widely used component in electronic circuits, after resistors. Indeed, in any electronic device, be it a multivibrator with 2 transistors or a computer motherboard, these radioelements are used in all of them.

A capacitor has the ability to accumulate charge and subsequently release it. The simplest capacitor consists of 2 plates separated by a thin layer of dielectric. The capacitance of a capacitor depends on its capacitance and the frequency of the current. The capacitor conducts AC and does not miss the constant. The capacitance of the capacitor is greater, the larger the area of the plates (plates) of the capacitor, and the greater, the thinner the dielectric layer between them.

The capacitances of parallel connected capacitors add up. The capacitances of series-connected capacitors are calculated using the formula shown in the figure below:

Capacitors come in both fixed and variable capacitance. The latter are called and abbreviated as KPE (variable capacitor). Fixed capacitors can be either polar or non-polar. The figure below shows a schematic representation of a polar capacitor:

Electrolytic capacitors are polar. Tantalum capacitors are also produced, which differ from aluminum electrolytic capacitors in that they are more stable, but are also more expensive. Electrolytic capacitors are subject to faster aging compared to non-polar ones. Polar capacitors have positive and negative electrodes, plus and minus. The photo below shows an electrolytic capacitor:

For Soviet electrolytic capacitors, the polarity was indicated on the body with a plus sign near the positive electrode. For imported capacitors, the negative electrode is indicated with a minus sign. If the operating conditions of electrolytic capacitors are violated, they can swell and even explode. For electrolytic capacitors, in order to avoid explosion, special notches are made on the housing cover during their manufacture:

Electrolytic capacitors can also explode if they are mistakenly applied at a voltage higher than what they were designed for. In the photo of the electrolytic capacitor above, you can see the inscription 33 μF x 100 V., this means its capacity is equal to 33 microfarads and the permissible voltage is up to 100 volts. A non-polar capacitor in the diagrams is designated as follows:

Non-polar capacitor image on the diagram

The photo below shows film and ceramic capacitors:

Film

Ceramic

Capacitors are distinguished by the type of dielectric. There are capacitors with solid, liquid and gaseous dielectric. With a solid dielectric these are: paper, film, ceramic, mica. There are also electrolytic capacitors, which have already been discussed above, and oxide-semiconductor capacitors. These capacitors differ from all others in their high specific capacitance. Many, I think, have seen the following digital designation on imported capacitors:

The figure above shows how you can calculate the value of such a capacitor. For example, if a capacitor is marked 332, this means that it has a capacity of 3300 picofarads or 3.3 nanofarads. Below is a table, by consulting which you can easily calculate the value of any capacitor with this marking:

There are capacitors in SMD design, the most common in amateur radio designs, I think, are types 0805 and 1206. An image of a non-polar SMD capacitor can be seen in the figures below:

The industry also produces so-called solid-state capacitors. Instead of an electrolyte, they have an organic polymer inside.

Variable capacitors

Like resistors, some special capacitors can change their capacitance if necessary during the tuning process. The figure shows the device of a variable capacitor:

The capacitance in variable capacitors is adjusted by changing the area of parallel capacitor plates. Capacitors are divided into variable ones, which have a handle for rotating the shaft, and trimmers, which have a slot for a screwdriver, and also consist of moving and non-moving parts.

In the figure they are designated as rotor and stator. Such capacitors are used in radio receivers to tune to the desired broadcast frequency. The capacity of such capacitors is usually small and equal to a few - a maximum of hundreds of picofarads. This is how a variable capacitor is designated in the diagrams:

The following figure shows a trimmer capacitor. The trimmer capacitor is designated in the diagrams as follows:

Such capacitors are usually adjusted only once during the assembly and configuration of electronic equipment.

The following figure shows the structure of a trimmer capacitor:

The capacitance of a capacitor is measured in Farads. But even 1 Farad is a very large capacity, so parts per million Farads, microfarads, as well as even smaller ones, nanofarads and picofarads are usually used for designation. Converting from microfarads to picofarads and back is very easy. 1 microfarad is equal to 1000 nanofarads or 1,000,000 picofarads. Capacitors, among other things, are used in oscillating circuits of radio receivers, in power supplies to smooth out ripples, and also as isolation circuits in amplifiers. Review prepared AKV.

Discuss the article CAPACITOR

This integral element of almost all electrical circuits is available in several modifications. The need to determine the polarity of a capacitor applies to electrolytic capacitors, which are, due to design features, something between a semiconductor and a passive circuit element. Let's figure out how this can be done.

Methods for determining capacitor polarity

By labeling

For most domestic electrolyte capacitors, as well as a number of states of the former socialist camp, only a positive conclusion is indicated. Accordingly, the second one is a minus. But the symbolism may be different. It depends on the country of manufacture and year of manufacture of the radio component. The latter is explained by the fact that over time they change regulatory documents, new standards come into force.

Examples of capacitor plus designation

There is a “+” symbol on the body near one of the legs. In some episodes it passes through its center. This applies to cylindrical capacitors (barrel-shaped), with a plastic “bottom”. For example, K50-16.
For capacitors of the ETO type, the polarity is sometimes not indicated. But you can determine it visually by looking at the shape of the part. The “+” terminal is located on the side with a larger diameter (in the figure there is a plus at the top).

If the capacitor (the so-called coaxial design) is intended for installation by connecting the housing to the “chassis” of the device (which is a minus of any circuit), then the central contact is a plus, without any doubt.

Minus symbol

This applies to imported capacitors. Next to the “–” leg, on the body there is a kind of barcode, which is a broken strip or a vertical row of dashes. Alternatively, a long strip along the center line of the cylinder, one end of which points to the minus. It stands out from the general background with its shade.

By geometry

If the capacitor has one leg longer than the other, then this is a plus. Basically, imported products are also labeled in a similar way.

Using a multimeter

This method of determining the polarity of a capacitor is practiced if its markings are difficult to read or completely erased. To check, you need to assemble a circuit. You will need either a multimeter with an internal resistance of about 100 kOhm (mode – I= measurement, limit – microamps)

or source DC+ millivoltmeter + load

What to do

Completely discharge the capacitor. To do this, it is enough to short-circuit its legs (with the tip of a screwdriver or tweezers).
Connect the container to the open circuit.
After the charging process is completed, record the current value (it will gradually decrease).
Discharge.
Include it in the diagram again.
Read the instrument readings.

If the positive probe of the multimeter was connected to the “+” of the capacitor, then the difference in readings should be insignificant. If the polarity is reversed (plus to minus), then the difference in the measurement results will be significant.

Recommendation. It is advisable to determine the polarity with the device in any case. This will allow you to simultaneously diagnose the part. If an electrolyte with a large nominal value is charged relatively quickly from a source of 9±3 V, then this is evidence that it has “dried up”. That is, it has lost part of its capacity. It is better not to put it in the circuit, since its operation may be incorrect, and you will have to make additional settings.

Electrical capacitors are common components of any pulsed, electrical or electronic circuit. Their main task is to accumulate charge, which is why they are called passive devices. Electric capacitors consist of two metal electrodes in the form of plates (plates). A dielectric is placed between them, the thickness of which is much less than the dimensions of the plates themselves.

General information

When included in electrical circuit Polarity determination for such elements is not necessary. But there are electrolytic capacitors, which are considered unusual electronic components, since they combine the functions of not only a storage element, but also a semiconductor device. They are characterized by a larger capacity compared to others and small overall dimensions. The capacitor leads themselves are located radially (on different sides of the device) or axially (on one side).

These devices are widely used in many electrical and radio equipment, computers, measuring instruments, etc. For them, the definition of polarity and correct connection to the network are required.

Pay attention! They can explode if a voltage higher than designed is mistakenly applied to them. Its value is mainly indicated by the manufacturer on the product body.

Polarity of domestically produced capacitor

The polarity designation symbols may vary depending on the manufacturer and the time of manufacture of the radio component. It is clear that over time, regulations defining the standardization system change. How to find out the polarity:

IN former countries It was customary in the USSR to designate only the positive terminal on such devices. On the body you need to find the “+” sign; the end to which it is closest is the anode. Accordingly, the second one is a minus. Czech capacitors of older releases have similar markings;
The bottom of electrolytic capacitors type K50-16 is made of plastic, where the polarity is written. There are cases where the plus and minus signs are placed so that the terminals intersect their centers;
There are also devices of non-standard design that provide connection to the chassis. They have mainly found application in lighting lamps, namely in anode voltage filters (always positive). Such capacitors have a plate - the cathode is connected negatively and is brought out to the body, and the anode is a terminal coming out of the element;

Pay attention! This type may have completely opposite polarity, so be sure to study the markings on the device.

The often discontinued series of capacitors ETO appearance confused with diodes. They are also marked, but if the markings are erased, then the end that comes out of the thickening of the body is the anode. Such devices cannot be disassembled; they contain harmful substances;
The polarity of current electrolytic capacitors of various designs can be easily determined by the stripe near the minus terminal. Usually it is made as a broken line and applied with bright paint.

By appearance, one can also conclude about the polarity: a longer leg (lead) indicates “plus”.

Determining polarity when markings are erased

In this case, you need to assemble a simple electrical circuit:

Before this, it is imperative to discharge the capacitor used, for example, short-circuit its legs using a screwdriver;
In a certain circuit, we connect in series a direct current source (an ordinary battery), a millivoltmeter, a resistor with a resistance of 1 kOhm, a microammeter and our discharged device;
Then on this diagram voltage is applied, and the electrolytic capacitor will begin to accumulate charge;
After it is fully charged, it is necessary to record the readings of the device by measuring the current strength;
Next, remove and discharge the drive. This can be done by connecting the two outputs of the device to a lamp. If it goes out, it means our capacitor is discharged;
We reassemble the circuit and charge the polar element again;
We take new current readings and compare them with the data obtained for the first time. If the “+” of the capacitor was connected to the plus of the millivoltmeter, then the presented measurement data will differ slightly. The opposite result will mean that the polarity of the drive is reversed.