An ammeter is an electrical measuring device designed to record the strength of a direct or alternating current flowing in a circuit - that is, current measuring device... connected in series with the section of the electrical circuit where the current is supposed to be measured. Since the current that it measures depends on the resistance of the circuit elements, the resistance of the ammeter should be as low as possible (very small). This makes it possible to reduce the influence of the current measuring device on the measured circuit and increase their accuracy.

The instrument scale is calibrated in μA, mA, A and kA, and a suitable instrument is selected depending on the required accuracy and measurement limits. An increase in the measured current strength is achieved by including shunts and magnetic amplifiers in the circuit. This allows you to increase the limit of the measured value of the current.

Ammeter connection diagrams

Figure - Diagram of direct connection of the ammeter

Figure - Scheme of indirect connection of an ammeter through a shunt and a current transformer

Scope of application of ammeters

Instruments for measuring current have found application in various fields. They are actively used at large enterprises related to the generation and distribution of electrical and thermal energy. They are also used in:

- electrical laboratories;

- automotive industry;

- exact sciences;

- construction.

But not only medium and large enterprises use this device: they are in demand among ordinary people. Almost any experienced auto electrician has a similar device in his arsenal, which makes it possible to measure the indicators of electrical consumption of devices, car assemblies, etc.

Types of ammeters

Based on the type of reading device, they are divided into devices with:

- with a pointer;

- with a light indicator;

- with a writing device;

- electronic devices.

5. Electrodynamic devices are designed to measure the magnitude of the current in circuits / alternating currents increased frequencies(up to 200 Hz). They are sensitive to overloads and external electromagnetic fields. But due to the high accuracy of measurements, they are used as control devices for checking operating ammeters.

- Measurement error 1%

- Discreteness of indication 0.1 A

- power supply -100 ... -400 V, 50 (+1) Hz Overall dimensions 90x51x64 mm

The performance and durability of household electrical appliances depend on the quality of the electricity received. As a rule, to the failure of electronic equipment, be it refrigerators, televisions or washing machines, results in an increase above acceptable limits. The most dangerous is a prolonged increase above the permissible level. In this case, the power supplies of electronic equipment fail, the windings of the electric motors overheat, and fire often occurs.

2. Laboratory ammeter E537

This device (ammeter E537) is designed to accurately measure the current in AC and DC circuits.

Accuracy class 0.5.

Measurement ranges 0.5 / 1 A;

Weight 1.2 kg.

Specifications ammeter E537:

Measurement range end value 0.5 A / 1 A

Accuracy class 0.5

Normal frequency range (Hz) 45 - 100 Hz

Operating frequency range (Hz) 100 - 1500 Hz

Overall dimensions 140 x 195 x 105 mm

3. Ammeter CA3020

The digital device of the basic model is produced in several typical modifications, depending on the base value of the parameters of the measured current. When ordering this model of a digital ammeter, you need to declare which basic parameter of the current strength you will have to work with: 1 A, 2 A or 5 A.

Basic parameters of the measured current, In-1 Ampere (CA3020-1), 2 Ampere (CA3020-2) or 5 Ampere (CA3020-5);

Limits of measured currents from 0.01 In to 1.5 In;

The frequency range for the measured currents is from 45 to 850 Hertz;

The boundaries of the basic permissible existing error ± 0.2% to the optimal value of the parameters of the measured current strength;

Power supply - AC network with voltage (85-260) Volts and frequency (47-65) Hertz or constant (120 - 300) Volts;

The power consumed by the device is not more than 4 VA;

Dimensional dimensions 144x72x190 mm;

Weight is not more than 0.55 kg;

The power consumed by the measuring circuit of the 3020 series does not exceed: for CA3020-1 - 0.12 VA; for CA3020-2 - 0.25 VA; for CA3020-5 - 0.6 VA.

Connecting an ammeter through a shunt. Selection and calculation of the device. Ammeter of the switching circuit

How to connect an ammeter to take readings

Electrical circuits have become an integral part of modern life. They permeate almost everything, and people do not even think that if an electric current disappears, our world will be in serious danger. What is current, can it be measured and what will these readings give for an ordinary person?

The laws of current behavior are studied at school, and, in principle, every high school student knows about the directed motion of charged particles. This movement of electrons inside a conductor is called electricity. But any movement in nature - let that movement of water in a river, movement of air masses or charges, can make a certain useful work... And this is already interesting from a practical point of view. Knowing the power, duration of exposure, the direction of application of any force, you can use it in solving certain life issues.

Therefore, scientists are so busy studying the environment and creating instruments that allow everything to be measured and calculated. To get an idea of the current, an ammeter was invented. It allows you to determine the number of charged particles that per unit time pass through a known cross-section of the conductor, that is, the current strength.

What is an ammeter, its types

An ammeter can measure the current in any electrical circuit. This device is easy to recognize, it is denoted by the Latin letter A. Since the current is of different magnitude, ranging from milliamperes and above, there are devices of different power or universal in which the measurement limit changes. Moreover, for direct and alternating current, different types ammeters.

By the principle of the device, devices are:

Electromagnetic execution.
Magnetoelectric.
Thermal.
Detector type.
Induction.
Electrodynamic system.
Photovoltaic.
Thermoelectric.

A magnetoelectric device can determine the current strength in circuits connected to constant voltage. Detector and induction type - measure alternating currents. All other types can be universal.

High sensitivity and accuracy of indications are possessed by ammeters of electrodynamic and magnetoelectric design.

How to connect an ammeter to an electrical circuit

An ammeter of any type is connected in series with the load in an electrical circuit. Then the same current flows through it as through the circuit. In order not to influence the current, not to obstruct it, the device is made with a low input resistance. It must be remembered that by connecting the ammeter in parallel with the load (incorrect connection), all the current will go through it according to the principle of least resistance. Forgetting how to connect an ammeter, you can simply burn the device!

Before choosing a device, you need to know the type of current - alternating or direct. After that, taking the appropriate ammeter (in the marking of the scale, the sign of the wave is usually indicated for alternating voltage and a straight line for a constant) set the maximum measurement limit on it and only then think about how to connect the ammeter to the circuit. After that, it is necessary to take the readings of the device. If they are significantly less than the set measurement limit, for example, the arrow is in the first half of the scale counting from zero, then it is necessary to move the limit down by one. Readings are considered more accurate when the arrow is located in the second half of the scale.

Measurement of DC values

Direct currents are present in many electronic circuits, especially for power supplies, various chargers. To repair such devices, craftsmen just need to know how to connect an ammeter. In practice, an ordinary person, not associated with radio electronics, can also apply this knowledge, for example, to determine how much the charge holds. accumulator battery from the camera.

Take a fully charged battery. Let's assume its nominal voltage is 3.5 volts (V). A light bulb is selected for this denomination and a circuit is assembled: a battery - a measuring device - a light bulb. Record what the ammeter shows. For example, a light bulb consumes a current of 150 milliamperes (mA), and a capacity of 1500 milliampere-hours (mAh) is written on the battery, this means that good battery should deliver a current of 150 mA for about 10 hours!

Measurement of AC values

Any household electrical appliance is a load that draws alternating current. But, considering the issues of domestic use of electricity, power remains an important concept, because it is paid for kilowatts (kW). What is an ammeter in this case? Indirect measurement device. With the help of it, the current is recognized and applying the formula:

P = IU (Ohm's law), where I is the current (A), U is the voltage (V),

calculate the power (P) (W).

For example, information about its parameters is lost on the device, in this case, measurements cannot be done. Or you need to calculate the power consumption of electricity of a building, where it is simply impossible to take into account all the devices. Then a powerful ammeter is connected at the input from the power panel and measurements are taken. But in the latter case, you need an admission that only professional electricians have!

Non-contact method of measuring current

Sometimes break the electrical circuit to turn on measuring device technically impossible, but you need to measure the current (with regard to conventional and high-voltage electrical circuits). How to connect an ammeter in this case? For this, a device for non-contact current measurement was developed - a current clamp. Its principle of operation is based on the fact that any current passing through a conductor creates a certain electromagnetic field. The magnitude of this field is the greater, the greater the current strength. By measuring the field strength index and converting this data, the real value of the force is obtained, expressed in amperes.

This is a very convenient way to take measurements, because you do not need to think for a long time how to connect an ammeter. You can connect the clamp directly to the insulated wire to the charger and any electrical circuit and take readings.

Why do you need to control the charge current in the battery

It seems what is simpler: I connected the car battery to the charger, waited ten hours and the job is done - it is charged. In fact, it is very important to control the charging current, overcharging is just as harmful as an incompletely charged battery. This can lead to a reduction in its service life. Therefore, it is advisable to think about how to connect the ammeter to the charger.

When the circuit is assembled and turned on, the ammeter shows the magnitude of the charge current. If the battery is healthy but discharged, it will gradually take charge. That is, the charge current will begin to decrease slowly (over several hours) until it stops at a certain value. When this happens, it is advisable to disconnect the battery from the charger. If there is a sharp decrease in the current from the initial value (within half an hour), then the battery may be faulty.

Very good chargers have a function for adjusting the charging current. Then, at the beginning of the process, you should set the charge current ten times less than the nominal capacity of the battery, which is indicated in its technical parameters.

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Connecting ammeters in AC and DC networks

We come across current measurement very often. In order to find out the power of the device, the cross-section of the cable for its power supply, the heating of wires and other elements - it all depends on the strength of the current. In order to directly measure this force, a device called an ammeter was invented. The ammeter is connected to the measured circuit only in series. Why? Let's take a look below.

As you know, the current strength is the ratio of the number of charges ∆Q that have passed through a certain surface during the time ∆t. In the SI system, it is measured in amperes A (1 A = 1 C / s). In order to measure the amount of passed charges, the ammeter must be connected to the circuit in series.

To minimize the effect of the measuring resistance of the ammeter and, accordingly, reduce the power losses during measurement, it is made as small as possible. If an ammeter with such an internal resistance is connected in parallel, a short circuit will occur in the circuit. An example of a wiring diagram:

Direct current is measured by direct assessment devices in the range of 10-3 - 102 A, electronic analog, digital, magneto-electric, electromagnetic, electrodynamic devices - milliammeters and ammeters. If the current exceeds 100 A, a shunt is used:

Shunts are usually made for different currents. A shunt is a copper plate that has a certain resistance. When current flows through the plate, some voltage falls on it, according to Ohm's law U = I * R, that is, a voltage appears between points 1 and 2, which will act on the coil of the device.

The shunt resistance is usually selected from the ratios:

Where Ri is the resistance of the measuring winding of the device, is the shunting coefficient, I is the measured one, and Ii is the maximum permissible current of the measuring mechanism.

If an alternating current is measured, then it is important to know what value is being measured (amplitude, average, effective). This is important, since all scales are usually calibrated in terms of the effective values.

Variable values above 100 μA are usually measured with rectifying microammeters, and below 100 μA - with digital microammeters. For measurements in the range from 10 mA to 100 A, rectifier, electrodynamic, electromagnetic devices are used that operate in the frequency range up to several tens of kilohertz, as well as thermoelectric ones, the frequency range of which is up to hundreds of megahertz.

To measure variables from 100 A and above, devices are used, but using current transformers:

A current transformer is a device in which the primary winding is connected to a current source (or, as seen from the figure below, the primary winding is "put on" a bus or cable), and the secondary winding is connected to the measuring winding of some measuring device (the winding of a measuring device or sensor should have low resistance).

Various methods and means are used to measure various kinds of currents. In order to correctly measure the required value and not cause any harm, you need to correctly apply each measurement method.

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Don't know how to connect an analog ammeter

If you have a conventional analog ammeter and you do not know how to connect it, then this is very easy to do. In addition to an ammeter, you need a SHUNT, since the ammeter measures the voltage drop across the shunt. The wiring diagram for an ammeter with a shunt looks like this (figure below). If there is no shunt, then you can do it yourself, and more on that later in the article.

If there is an ammeter and there is no shunt to it, then you can do it yourself. As a shunt, you can take a piece of copper wire, the thickness of this wire depends on the current strength that will be measured. For example, for currents up to 10A, you can take a wire with a cross section of 1.5 kV, if the current is up to 30A, then it is better to take a 2.5 kV wire.

A piece of about 30 cm is needed, it must be stripped completely of insulation. Next, we connect this wire instead of the shunt, in the picture below I think everything is clear.

Such a shunt is no worse than a factory one, except of course appearance... And calibrating the ammeter is quite simple. We need a second ammeter, which is connected in series with our shunt. You can before our homemade shunt, or after. We connect the energy consumer to the power source and see how much the second ammeter shows. Next, we look at our ammeter and on a homemade shunt we move the contacts of the ammeter, bring them closer or remove them from each other so that the readings on both ammeters are the same. That's all, when the readings of the ammeters are the same, then it remains only to solder the contacts from the ammeter to the shunt so that they do not move and the ammeter does not go astray.

After that, the ammeter is ready to work, and the homemade shunt can be placed in some kind of case or hidden from the eyes if you don't like it. In addition, the shunt can be made not only from copper wire. A metal plate will do, even a simple bolt where you can clamp the wires from the ammeter with nuts and adjust the distance between the wires to calibrate the device.

Below in the photo is my ammeter with a homemade shunt.

I did not measure the length of the active zone of the shunt, so I cannot say at what distance to solder the wires from the ammeter. Well, the cross-section of the copper wire can be different and the ammeter itself, too, so you still have to calibrate this. I did this with a multimeter. A few more photos of an ammeter with a homemade shunt.

This is how it looks from the back side, you can see how the wires come out of the ammeter and how they are connected to this copper shunt

I think it's clear how the ammeter works and how to connect the shunt. The shunt is connected in series, that is, in the rupture of one of the wires going to the energy consumer. You can put a shunt on a plus or minus one. If the needle of the ammeter deviates in the wrong direction, then you just need to turn the shunt over. And so the ammeter measures the voltage drop across the shunt, the voltage drop there in millivolts.

Factory shunts, in my opinion, are almost all with a voltage drop of up to 75 mV, and the shunt must be selected according to the characteristics of the ammeter. If the ammeter is 50A and 75mV, then the shunt must be bought the same, otherwise the ammeter will show incorrectly. "I hope this information helped you, thanks for reading and leave your comments.

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AMMETER DIAGRAM

Certain circuits and devices, such as power amplifiers, car chargers, and laboratory power supplies, may have currents of up to 20 amperes or more. It is clear that a couple of amperes can be easily measured with an ordinary cheap multimeter, but what about 10, 15, 20 and more amperes? Indeed, even at not very large loads, the shunt resistors built into the ammeters for a long measurement time, sometimes even hours, can overheat and, in the worst case, will melt.

Professional instruments for measuring high currents are quite expensive, so it makes sense to assemble the ammeter circuit yourself, especially since there is nothing complicated here.

Electrical circuit of a powerful ammeter

The circuit, as you can see, is very simple. Its operation has already been tested by many manufacturers, and most industrial ammeters work in the same way. For example, this scheme also uses this principle.

Drawing of the board of a powerful ammeter

The peculiarity lies in the fact that in this case a shunt (R1) with a very low resistance value - 0.01 Ohm 1% 20W is used - this makes it possible to dissipate very little heat.

Ammeter circuit operation

The operation of the circuit is quite simple, when a certain current passes through R1, there will be a voltage drop across it, it can be measured, for this, the voltage is amplified by the OP1 operational amplifier and goes further to the output through pin 6 to an external voltmeter turned on at the 2V limit.

The settings will be to set the output of the ammeter to zero in the absence of current, and to calibrate, comparing it with another, exemplary instrument for measuring current. The ammeter is powered by a stable symmetrical voltage. For example, from 2 batteries of 9 volts. To measure current, connect the sensor to the line and a multimeter in the 2V range - see the readings. 2 volts will correspond to a current of 20 amperes.

With a multimeter and a load such as a small light bulb or resistance, we will measure the load current. Connect the ammeter and get current readings using a multimeter. We recommend that you run several tests with different loads in order to compare the reading with the reference ammeter and make sure everything is working correctly. You can download the printed plate file here.

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What is a shunt? This word is borrowed from of English language("Shunt", and literally means "branch"). Physically, this is comparable, since most of the current flows through this element, connected in parallel to the measuring device, and a smaller part is branched off into the device itself. In this, its principle of operation is similar to the bypass installed in heating systems.

To understand the need to turn on the ammeter through the shunt, let us briefly recall its design.

Inside the field of a permanent magnet is a coil - a frame. The measured current flows along its turns. Depending on the value of the measured parameter, the position of the coil relative to the constant magnetic field changes. The arrow of the device is rigidly fixed on its axis. The greater the measured current, the more the pointer deflects.

In order for the frame to be able to rotate, its axis is fixed in the thrust bearings, or hung out on the braces. When using thrust bearings, the current of the frame passes through the spiral springs, but if the moving part of the device is suspended on braces, then they are current conductors.

It follows from this design that the amount of current in the frame is structurally limited. Springs and braces cannot simultaneously be sufficiently elastic and have a large cross-section.

Ammeter connection via current transformer

Expanding the measurement range of the ammeter is possible if you use an additional device called a current transformer. It works on the principle of a conventional transformer, but the primary winding contains only a few turns. When the measured current passes through it, its value in the secondary winding will be several times less.

But such transformers have appropriate dimensions and are used only in industrial networks. In small-sized devices, their use is impractical.

Connecting an ammeter through a shunt

If the device is connected directly to the measuring circuit, without a current transformer, it is called a direct connection ammeter.

Without a shunt, you can use devices designed for a small current strength, of the order of milliamperes. By shunting the measuring winding with a resistance greater than its own, we can change the measurement limit. The switching circuit does not differ in complexity: the measured current passes through the shunt, and an ammeter is connected in parallel to it.

The first Kirchhoff's law comes into play here. The measured current is divided into two: one flows through the frame, the other through the shunt.

They will relate to each other as follows:

Calculation of shunt resistance

It follows that, knowing the total deflection current of the measuring system (Ipr) and the internal resistance of the frame (Rpr), it is possible to calculate the required shunt resistance (Rsh). And thereby change the measurement limit of the ammeter.

But, before converting a milliammeter into an ammeter, you need to solve two difficult problems: find out the total deflection current of the measuring system and its resistance. You can find this data by knowing the type of milliammeter that is being converted. If this is not possible, a series of measurements will have to be taken. Resistance can be measured with a multimeter. But for the second parameter, you will need to supply current to the device from an external source, measuring its value using a digital ammeter.

But this calculation of the shunt for the ammeter will not be accurate. It is impossible to provide the required measurement accuracy with the help of available tools. The shunt measuring system is highly sensitive to the error in determining the initial data. Therefore, in practice, the shunt resistance is accurately adjusted and the ammeter is calibrated.

Fitting the measuring system

For the manufacture of factory products, materials are used that do not change their characteristics over a wide temperature range. Therefore, the best option is to select a ready-made shunt and fit it for your own purposes by reducing the cross-section and length of its conductor to match the calculated value. But for the manufacture of a shunt for an ammeter, you can also use improvised materials: copper or steel wire, even paper clips will do.

Now you need a power supply with a voltage regulator to supply the required current. For the load, you can use a resistor of appropriate power or incandescent lamps.

First, we achieve compliance with the full deviation of the arrow of the device at the maximum value of the measured value. At this stage, we select the resistance of our homemade product to the maximum possible coincidence with the final risk on the scale.

Then we check if the intermediate risks coincide with their corresponding values. If not, we disassemble the ammeter and redraw the scale.

And when everything worked out, we install the finished device in its place.

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Quite often in our life a situation arises in which we need to measure the current strength. For what? To find out the estimated power of a particular equipment, for example. To determine the potential level of heating of the cable, and so on. For approximately these purposes, we will need an alternating current ammeter. It is he who serves to measure the current strength. By the way, with the help of the device, you can measure the strength of not only alternating, but also direct current. How do I use this tool?

Connection

To understand how to connect an ammeter, you need to understand the principle of the measuring range. That is, the instrument operates within a specific range, measuring from μA values to kA values. Taking into account the technical connection diagram, the maximum current level of the scale should be outstripped. The connection itself takes place in series, and not in parallel with the existing load. Otherwise, there is a danger of overvoltage of the device. Accordingly, it will become non-functional, in other words, it will burn out.

An important point is that the measured current is highly dependent on the total resistance of the circuit. It follows from this that the internal resistance of the device should be extremely small. Otherwise, the accuracy class of the results may be questionable. After all, the equipment itself will affect the numeral. To understand more precisely, you need an ammeter connection diagram.

Shunt

How to connect an ammeter if the current required for measurement exceeds the capabilities of the device? For this, a variety of shunts are used. They allow you to expand the measurable current range. The load will be distributed in favor of the shunt, it will take over most of it. In fact, the shunt will simply show a decrease in current, which the device will fix. In this case, it will work on the principle of a millivoltmeter, however, its readings will be in amperes, which means that the final information will be correct.For a more detailed understanding, a circuit for connecting an ammeter through a shunt is required.

Where is the ammeter used?

The DC ammeter is used everywhere. If we exclude household needs, then the first option would be large industrial enterprises. Naturally, only those who, in one way or another, are engaged in the creation (generation) and further consumption of electrical or thermal energy. In addition, the device has found wide application in construction. No serious project goes without this little helper.

Variety of equipment

The ammeter device can be quite different depending on the model. If we classify them according to the type of reading, it is possible to distinguish arrow, light and electronic options. The DC ammeter can be different as well as the ways of its functioning. Here the row is wider, and it is worth dwelling on it in more detail.

Electromagnetic ammeters are required for measuring alternating current with a low frequency. Ammeter circuit of this type the simplest, respectively, they are the cheapest on the market. If you are wondering what the name of a device for measuring current strength with a high frequency is, then this is a thermoelectric meter. The principle of operation of an ammeter of this kind consists in the operation of a conductor and a thermocouple. The conductor, using the current passing through it, heats the thermocouple, which serves as a way to calculate the current strength.

Ferrodynamic devices are required for stressful environments with increased magnetic field... They are more resistant to external and internal influences. The latest technology is the digital ammeter. These are the most progressive models that are not afraid of strong stress and mechanical damage. They are much easier to learn and use. How to connect a digital ammeter? In most cases, unless the manufacturer has indicated otherwise, just like the usual one.

On this, the main types of ammeters can be considered exhausted. Some users, however, think that we missed one view. Namely a voltmeter.

Differences between a voltmeter and an ammeter

First, let's just take a look at the etymology of words. It is immediately clear that the devices originated from the words "ampere" and "volt". And although the first one can be connected to the same circuit as the voltmeter, their purpose is completely different. Ampere is a unit of measure for current, while volt is a unit of voltage. So how does an ammeter differ from a voltmeter? That's right, the first measures strength, and the second measures tension.

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When making homemade power supplies or chargers, craftsmen often equip such devices with digital voltammeters. The price of such devices fluctuates in the region of several dollars, and their accuracy allows you to completely forget about dial gauges. Given the wide range of modern voltammeters, you may encounter the problem of connecting them. Today our article is devoted to the most popular voltammeters and their connection schemes. Also, in addition to the standard circuit, we will describe how to connect the voltammeter to the charger.

How to connect a voltammeter to a charger - a selection of diagrams

We have selected 4 of the most common voltammeters that craftsmen use in their devices. The measuring ranges of most devices are 0-100 V, and also have a built-in 10 A shunt. The connection principle is very similar, but there are some nuances.

Voltammeter TK1382 can be purchased at a price of 3.5-5 USD. The device has two calibration resistors: voltage adjustment, current adjustment.

Measured voltage 0-100 V; current 0-10 A. The power supply of the device must be within 4.5-30 V.

YB27VA connection diagram

Voltmeter ammeter YB27VA has similar parameters for the range of current and voltage measurements. The only difference is the different board layout and wire color coding.

The approximate price is 3.5-4.5 cu, there are also trimmer resistors on the board.

DSN-VC288 connection diagram

Voltmeter ammeter DSN-VC288 is also one of the most popular among radio amateurs. Its price fluctuates within 4 USD.

Many who have come across such devices complain about the poor quality of the calibration resistors.

BY42A connection diagram

Anyone who needs high measurement accuracy can use the BY42A voltammeter. Such a device will give one more decimal place.

Voltmeter ammeter BY42A is designed for a higher measured voltage - up to 200 V, but the supply voltage of the device should be within 3.8-30 V.

Also BY42A can be found in two versions of the board, but the color coding of the wires remains the same.

Using a voltammeter in your car charger, you can not only visually monitor the battery charging process, but also diagnose the battery condition in a timely manner. It will be enough to connect the charger, where the voltammeter is installed, to the battery, and we will see what voltage is on it now.

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Designation diode bridge in the diagram

Corner wardrobe drawings and diagrams photo

A piece of about 30 cm is needed, it must be stripped completely of insulation. Next, we connect this wire instead of the shunt, in the picture below I think everything is clear.

Such a shunt is no worse than a factory one, except of course the appearance. And calibrating the ammeter is quite simple. We need a second ammeter, which is connected in series with our shunt. You can before our homemade shunt, or after. We connect the energy consumer to the power source and see how much the second ammeter shows. Next, we look at our ammeter and on a homemade shunt we move the contacts of the ammeter, bring them closer or remove them from each other so that the readings on both ammeters are the same. That's all, when the readings of the ammeters are the same, then it remains only to solder the contacts from the ammeter to the shunt so that they do not move and the ammeter does not go astray.

Below in the photo is my ammeter with a homemade shunt.

This is how it looks from the back side, you can see how the wires come out of the ammeter and how they are connected to this copper shunt

A miniature Chinese voltmeter can simplify the process of measuring the voltage and the amount of current consumed on a power supply or homemade charger. Its cost rarely exceeds 200 rubles, and if you order it from China through partnership programs, you can also get a tangible discount.

To the charger

Those who like to design chargers on their own will appreciate the opportunity to observe the voltages and amperes of the network, without the help of bulky portable devices. It will also appeal to those who work on expensive equipment, the operation of which can be adversely affected by a regular drop in mains voltage.

With the help of a Chinese ampere-voltmeter, which is no larger than a match box, you can easily monitor the condition electrical network... One of the tangible problems faced by newcomers to electricians can be the language barrier and different wire markings. Not everyone will immediately understand which wire to connect to, and the instructions are usually only in Chinese.

Devices for 100 V / 10 A are very popular among independent designers. It is also desirable that the device has a shunt to refine the connection process. A tangible plus this device is that it can be connected to the power supply of the charger or to a self-contained battery.

* The voltage of the power supply of the ammeter, voltmeter should be in the range from 4.5 to 30 V.

The connection diagram is as follows:

The black wire is a minus. It must also be connected to a minus.
The red wire, which should be thicker than the black one, is a plus and must be connected to the power supply accordingly.
The blue wire connects the load to the mains.

If everything was connected correctly, two scales should be highlighted on the scoreboard.

To the power supply

Power supplies perform important role, align the network readings to the desired state. If not properly operated, they can severely harm expensive equipment, causing overheating. In order to avoid problems during their operation, and especially in cases where the power supply is made by hand, it is advisable to use an inexpensive ammeter, voltmeter.

From China you can order the most different models, but for standard devices powered by home network suitable are those that measure current from zero to 20 A, and voltage up to 220 V. Almost all of them are small-sized and can be installed in small power supply cases.

Most devices can be adjusted using built-in resistors. In addition, they are highly accurate, almost 99%. The scoreboard displays six positions, three for voltage and current. They can be powered either from a separate or from a built-in source.

To connect a voltmeter, you need to deal with the wires, there are five of them:

Three thin. Black minus, red plus, yellow to measure the difference.
Two fat ones. Red plus, black minus.

The first three cords are most often combined for convenience. The connection can be carried out through a special socket connector, or using a solder.

* The connection by soldering is more reliable, with slight vibrations, the socket mount of the device may come loose.

Step by step connection:

It is necessary to decide from which power source the device will operate, separate or built-in.
Black wires are connected and soldered to the minus PSU. Thus, a general minus is created.
In the same way, you need to connect the thin red and yellow contacts. They are connected to the power supply.
The remaining red contact will be connected to the electrical load.

At wrong connection the instrument panel will show zero values. In order for the measurements to be as close as possible to the actual ones, the polarity of the supply contacts must be correctly observed. Only connecting the thick red wire to the load will give an acceptable result.

Note! Accurate voltage values can only be obtained from a regulated power supply. In other cases, the display will only show the voltage drop.

A popular voltmeter model that is often used by radio amateurs. Possesses the following characteristics:

Operating voltage DC 4.5 to 30 V.
Power consumption less than 20mA.
The display is two-color red and blue. Resolution 0.28 inches.
Performs measurements in the range 0 - 100 V, 0 - 10 A.
The lower limit is 0.1 V and 0.01 A.
The margin of error is 1%.
Temperature conditions of work from -15 to 75 degrees Celsius.

Connection

Using a voltmeter, you can measure the current voltage in the power supply network. To do this, you need the following:

Connect the black thick wire to the minus of the power supply.
Red is connected to the load, and then to the power supply.

This wiring diagram does not require the use of a thin black contact.

If a third party power supply is used, the connection will be as follows:

The thick cords are connected in the same way as in the previous example.
Subtle red connects to the plus side of a third party source.
Black with a minus.
Yellow with a plus source.

This voltmeter, ammeter is also convenient in that it is implemented in an already calibrated state. But even if inaccuracies were noticed in its work, they can be corrected using two tuning resistors on the back of the device.

What are the most reliable digital voltmeters

The electrical equipment market is overflowing with manufacturers who provide a wide variety of choices. However, not every device brings positive emotions from use. For a large number of products, it is not always possible to find a reliable and inexpensive copy.

Trusted and reliable voltmeters include:

TC 1382. Inexpensive Chinese, the average price of which rarely rises above 300 rubles. Equipped with tuning resistors. Carries out measurements in the ranges 0-100 Volts, 0-10 Amperes.
YB27VA. Almost a twin of the previous voltmeter, it differs in wire marking and a reduced price.
BY42A. It is more expensive than previous models, but also has an increased upper measurement limit of 200 V.

These are the most popular representatives of this type of voltmeter, which can be freely purchased for alteration on the radio market or ordered via the Internet.

Calibration of Chinese voltmeter ammeter

Over time, any technique wears out. Since the operation of measuring devices is affected not only by their own faults, but also by failures in the connected devices, sometimes it is necessary to make adjustments.

Most models have special resistors on their case. By rotating them, you can redo the zero values.

Everything measuring instruments have a measurement error, which is indicated in the documentation.

Conclusion

The inclusion of inexpensive voltmeters in the circuit avoids problems with inappropriate mains voltage. For a small fee, you can find out if the equipment works in the right conditions. To connect them, you need to know the marking of all wires and the location of the plus and minus of the energy source.

Shunt

How to connect an ammeter if the amount of current required for measurement exceeds the capabilities of the device? For this, a variety of shunts are used. They allow you to expand the measurable current range. The load will be distributed in favor of the shunt, it will take over most of it. In fact, the shunt will simply show a decrease in current, which the device will fix. In this case, it will work on the principle of a millivoltmeter, however, its readings will be in amperes, which means that the final information will be correct.
For a more detailed understanding, a circuit for connecting an ammeter through a shunt is required.

Where is the ammeter used?

The DC ammeter is used everywhere. If we exclude household needs, then the first option would be large industrial enterprises. Naturally, only those who, in one way or another, are engaged in the creation (generation) and further consumption of electrical or thermal energy.
In addition, the device has found wide application in construction. No serious project goes without this little helper.

Variety of equipment

The ammeter device can be quite different depending on the model. If you classify them by the type of reference, you can distinguish arrow, light and electronic options.
A DC ammeter can be different as well as the way it functions. Here the row is wider, and it is worth dwelling on it in more detail.

Electromagnetic ammeters are necessary for measuring alternating currents with a low frequency. The ammeter circuit of this type is the simplest, respectively - they are the cheapest on the market.
If you are wondering what is the name of a device for measuring high frequency current, then this is a thermoelectric meter. The principle of operation of an ammeter of this kind consists in the operation of a conductor and a thermocouple. The conductor, using the current passing through it, heats the thermocouple, which serves as a way to calculate the current strength.

Ferrodynamic devices are required for stressful environments with increased magnetic fields. They are more resistant to external and internal influences. The latest technology is the digital ammeter. These are the most progressive models that are not afraid of strong stress and mechanical damage. They are much easier to learn and use. How to connect a digital ammeter? In most cases, unless the manufacturer has indicated otherwise, just like the usual one.

On this, the main types of ammeters can be considered exhausted. Some users, however, think that we missed one view. Namely a voltmeter.