Chinese voltmeter wiring diagram. We connect the Chinese digital voltammeter. To power supply

Prelude

While somehow studying the vast expanses of the Internet for Chinese usefulness, I came across a digital voltmeter module:

The Chinese "rolled out" these performance characteristics: 3-digit red color display; Voltage: 3.2~30V; Working temperature: -10~65"C. Application: Voltage testing.

It didn’t quite fit me in the power supply (the readings are not from zero - but this is a retribution for the power from the circuit being measured), but it’s inexpensive.
I decided to take it and sort it out on the spot.

Schematic diagram of the voltmeter module

In fact, the module was not so bad. I soldered the indicator, drew a diagram (the numbering of parts is shown conditionally):

Unfortunately, the chip remained unidentified - there is no marking. Maybe it's some kind of microcontroller. The value of the capacitor C3 is unknown, I did not begin to measure it. C2 - presumably 0.1mk, also did not solder.

File in place...

And now about the improvements that are needed to bring this "display" to mind.

1. In order for it to start measuring a voltage of less than 3 Volts, you need to unsolder the jumper resistor R1 and apply a voltage of 5-12V from an external source to its right (according to the diagram) contact pad (higher is possible, but undesirable - the DA1 stabilizer is very hot). Apply the minus of the external source to the common wire of the circuit. Apply the measured voltage to the standard wire (which was originally soldered by the Chinese).

2. After the revision according to item 1, the measured voltage range increases to 99.9V (previously it was limited by the maximum input voltage of the DA1 stabilizer - 30V). The division factor of the input divider is about 33, which gives us a maximum of 3 volts at the input of DD1 at 99.9V at the input of the divider. I applied a maximum of 56V - I don’t have any more, nothing burned out :-), but the error also increased.

4. To move or completely turn off the point, you need to solder the R13 10kΩ chip resistor, which is located next to the transistor, and instead solder a regular 10kΩ 0.125W resistor between the pad farthest from the tuning chip resistor and the corresponding control segment output DD1 - 8, 9 or 10.
Normally, the point is illuminated at the middle digit and the base of the transistor VT1, respectively, is connected to the pin through a 10kΩ CHIP. 9DD1.

The current consumed by the voltmeter was about 15mA and varied depending on the number of illuminated segments.
After the described alteration, all this current will be consumed from an external power source, without loading the measured circuit.

Total

And in conclusion, a few more photos of the voltmeter.

factory condition

With soldered indicator, front view

With soldered indicator, rear view

I have already done a couple of reviews of a similar thing (see photo). I ordered those devices not for myself, for friends. A handy device for homemade charging, and not only. I also envied and decided to order already for myself. I ordered not only a voltammeter, but also the cheapest voltmeter. I decided to assemble a power supply for my homemade products. Which of them to put was determined only after I assembled the product completely. Surely there will be people who are interested.
Ordered November 11th. There was a small discount. Even though the price is low.
The parcel went for more than two months. The seller gave the left track from Wedo Express. But still the package arrived and everything works. Formally, there are no complaints.
Since it was this device that I decided to implant in my power supply, I’ll tell you a little more about it.
The device came in a standard plastic bag, “bubbled” from the inside.

The item is currently unavailable. But this is not critical. Ali now has a lot of offers from sellers with a good rating. Moreover, the price is steadily decreasing.
The device was additionally sealed in an antistatic bag.

Inside the actual device and wires with connectors.

Key connectors. On the contrary, do not insert.

The sizes are just tiny.

We look at what is written on the seller's page.

My translation with corrections:
- Measured voltage: 0-100V
- Circuit supply voltage: 4.5-30V
- Minimum resolution (V): 0.01V
- Consumption current: 15mA
- Measured current: 0.03-10A
- Minimum resolution (A): 0.01A
Everything is the same, but very briefly, on the side of the product.

I immediately took it apart and noticed that minor details were missing.

But in the previous modules, this place was occupied by a capacitor.

But their price was also different.
All modules look like twin brothers. Connection experience is also available. The small connector is designed to power the circuit. By the way, at a voltage below 4V, the blue indicator becomes almost invisible. Therefore, we follow the technical characteristics of the device, we do not supply less than 4.5V. If you want to use this device to measure voltages below 4V, you need to power the circuit from a separate source through a "connector with thin wires."
The current consumption of the device is 15mA (when powered by 9V "crown").
Connector with three thick wires - measuring.

There are two accuracy controls (IR and VR). Everything is clear in the photo. Resistors are dark. Therefore, I do not recommend twisting it often (you will break it). The red wires are the leads for voltage, the blue ones are for current, the black ones are “common” (connected to each other). The colors of the wires correspond to the color of the glow of the indicator, do not get confused.
The head chip is unnamed. It once was, but it was destroyed.

And now I will check the accuracy of the readings using the exemplary installation P320. I applied calibrated voltages 2V, 5V, 10V, 12V 20V, 30V to the input. Initially, the device underestimated by one tenth of a volt at certain limits. The error is insignificant. But I adjusted myself.

It can be seen that it shows almost perfectly. Adjusted the right resistor (VR). When the trimmer is rotated clockwise, it adds, when rotated counterclockwise, it decreases the reading.
Now I'll see how it measures the current strength. I power the circuit from 9V (separately) and supply an exemplary current from the P321 installation

The minimum threshold from which it starts to correctly measure the current is 30mA.
As you can see, the current measures quite accurately, so I won’t turn the adjusting resistor. The device measures correctly even at currents greater than 10A, but the shunt starts to heat up. Most likely, the current limit is for this reason.

At a current of 10A, I also do not recommend driving for a long time.
More detailed calibration results are summarized in a table.

I liked the instrument. But there are shortcomings.
1. The inscriptions V and A are painted, so they will not be visible in the dark.
2. The instrument measures current in one direction only.
I would like to draw attention to the fact that it would seem that the same devices, but from different sellers, can be fundamentally different from each other. Be careful.
On their pages, sellers often publish incorrect connection diagrams. In this case, there are no complaints. That's just a little of it (scheme) changed to a more understandable eye.

With this device, in my opinion, everything is clear. Now I'll tell you about the second device, about the voltmeter.
I ordered on the same day, but from a different seller:

Bought for US $1.19. Even with today's exchange rate - funny money. Since in the end I did not install this device, I will go through it briefly. With the same dimensions, the numbers are much larger, which is natural.

This device does not have a single tuning element. Therefore, you can only use it in the form in which it was sent. Let's hope for Chinese good faith. But I'll check.
The installation is the same P320.

More details in the form of a table.

Although this voltmeter turned out to be several times cheaper than a voltammeter, its functionality did not suit me. It does not measure current. And the supply voltage is combined with the measuring circuits. Therefore, it does not measure below 2.6V.
Both devices are exactly the same size. Therefore, replacing one with another in your homemade product is a matter of minutes.

I decided to assemble the power supply on a more universal voltammeter. The devices are inexpensive. There is no burden on the budget. The voltmeter is still in stock. The main thing is that the device is good, and there will always be an application. Just from the store and got the missing components for the power supply.
I have been idle for several years now with such a set of homemade.

The scheme is simple but reliable.

It is pointless to check the completeness, a lot of time has passed, it is too late to make claims. But everything seems to be in place.

The trimmer resistor (complete) is too dumb. I see no point in using it. Everything else will fit.
I know all the disadvantages of linear stabilizers. I have neither the time, nor the desire, nor the opportunity to fence something more worthy. If you need a more powerful power supply with high efficiency, then I'll think about it. Until then, what has been done.
First I soldered the stabilizer board.
I found a suitable case at work.
I rewound the secondary of the torroidal trance to 25V.

Picked up a powerful radiator for the transistor. All this stuffed into the body.
But one of the most important elements of the circuit is the variable resistor. I took a multi-turn type SP5-39B. The output voltage accuracy is the highest.

Here's what happened.

A little unsightly, but the main task is completed. I protected all electrical parts from myself, I also protected myself from electrical parts :)
It remains to "retouch" a little. I will paint the case from a spray can and make the front panel more attractive.
That's all. Good luck!

I plan to buy +64 Add to favorites Liked the review +63 +137

A miniature Chinese voltmeter can simplify the process of measuring 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 affiliate programs, you can also get a tangible discount.

To charger

Fans of independently designing chargers will appreciate the opportunity to observe the volts 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 ammeter, which is no larger than a matchbox, you can easily monitor the state of the electrical network. One of the tangible problems that beginner electricians have is the language barrier and wire markings that differ from the standard. Not everyone will immediately understand which wire to connect where, and instructions are usually only in Chinese.

100 V / 10 A devices are very popular with independent designers. It is also desirable that the device has a shunt to refine the connection process. A notable advantage of this device is that it can be connected to the power supply of the charger or to an independent 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 negative. It must also be connected to negative.
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 network.

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

To power supply

Power supplies play an important role, align the network readings to the desired state. If not operated correctly, they can severely damage expensive equipment by 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.

A variety of models can be ordered from China, but for standard devices powered by a home network, those that measure current from zero to 20 A and voltage up to 220 V are suitable. Almost all of them are small and can be installed in small power supply cases.

Most devices can be adjusted using built-in resistors. In addition, they have high accuracy, almost 99%. The display shows six positions, three for voltage and current. They can be powered both from a separate and from a built-in source.

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

Three thin ones. 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 made through a special female connector, or by soldering.

*Soldering connection is more reliable, with slight vibrations, the socket mount of the device may become 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 of the PSU. Thus, a general negative 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 connect to the electrical load.

If the connection is incorrect, the instrument panel will show zero values. In order for the measurements to be as close as possible to the real ones, it is necessary to correctly observe the polarity of the supply contacts. Only connecting a thick red wire to the load will give an acceptable result.

Note! You can only get accurate voltage values on a regulated power source. In other cases, the display will show only the voltage drop.

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

Operating voltage DC 4.5 to 30 V.
Power consumption less than 20 mA.
Dual color red and blue display. Resolution 0.28 inches.
Performs measurements in the range 0 - 100 V, 0 - 10 A.
Lower limit 0.1 V and 0.01 A.
Error 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 source.
Red connects to the load, and then to power.

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

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

Thick cords are connected in the same way as in the previous example.
Thin red is connected to the plus of a third-party source.
Black with minus.
Yellow with source plus.

This voltmeter, ammeter is also convenient because it is implemented in an already calibrated state. But even if inaccuracies were noticed in its operation, 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 crowded with manufacturers who provide a wide variety of choices. However, not every device brings positive emotions from use. For a large number of goods, it is not always possible to find a reliable and inexpensive copy.

Proven and reliable voltmeters include:

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

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

Chinese Voltmeter Ammeter Calibration

Over time, any technology wears out. Since the operation of measuring instruments is affected not only by their own malfunctions, but also by failures in the connected devices, sometimes you need to do some adjustment.

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

All 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 suitable 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.

When designing battery chargers and various power supplies, many radio amateurs use ready-made Chinese-made voltmeters-ammeters, which can be easily bought on the Internet, for example, on the Aliexpress website. Moreover, the cost of such ready-made devices is very attractive, and many suppliers, in addition to everything, carry out free delivery of goods to the buyer. Having found the most advantageous offer, we ordered a pair of WR-005 devices for testing, designed to measure voltage up to 100 Volts and current up to 10 Amperes. The order came, everything is in order with the blocks, there is no mechanical damage, but there was no passport or instructions describing how to connect the device. This was the reason for writing this article, because, most likely, we are not the only ones who are faced with issues of connecting the WR-005 to measurement circuits.

Similar measuring devices can be designed for other measurement parameters, but in any case, you will have two connectors on the board:

● The first connector has two thin wires, usually red and black. They serve to supply voltage to the measuring circuit. The supply voltage has a very wide range, you can apply from 4 to 30 volts, the red wire is positive, the black wire is negative. When power is applied to the circuit, the indicator will glow.
● The second connector is three-wire, the wires are thick, designed to connect the device to measuring circuits. But let's deal with the colors of the wires.

Apparently, indicators were produced earlier in which thick wires were black, red and yellow, so you can find this picture on the Internet:

In our case, this connector has blue, black and red wires, and the black wire is in the connector in the middle, so we decided to double-check them again.

As it turned out, globally nothing has changed:

● The black wire, as in the previous version, is a common wire (COM);
● Red wire - voltage measurement;
● Blue wire - current measurement.

For those who do not quite understand: the black thick wire is connected to the minus of the source, the red to the plus (the voltmeter will start to show), the blue thick wire is connected to the load, and from the second end of the load it goes to the plus of the source (the ammeter shows).

About the shunt. In devices up to 10 amperes, the shunt is built-in (soldered directly into the board), over 10 amperes, as a rule, an external shunt should be included, see the pictures below:

Our version of the device with a built-in shunt:

The external shunt looks like this:

Even after a correct connection, there is no guarantee that the readings of the voltmeter and ammeter will be correct, so it is worth checking them using, for example, an external multimeter. If necessary, you can correct the readings using trimming resistors located on the board of the WR-005 device.

The microcircuit on which the device is assembled does not have any identification marks, but the circuit diagram is as follows:

In conclusion, I would like to say that after connecting and testing the device, it showed itself on the positive side, the build quality is not bad, the reading errors correspond to those declared by the supplier, that is, the voltage error is 0.1 Volt, the current error is 0.01 Ampere, the current consumption of the measuring circuit does not exceed 20 mA. Any electronics is prone to fail over time, so how long this voltmeter-ammeter will serve us - time will tell. But, in principle, for such money, we believe that the WR-005 is a worthy purchase with quick installation and connection in devices that need to display digital indications of current and voltage parameters.

If anyone knows the brand of the microcircuit used in the device circuit, please write in the comments.

DIYers, designing, developing and implementing a variety of charger or power supply circuits, are constantly faced with an important factor - visual control of the output voltage and current consumption. Here, Aliexpress often lends a helping hand, promptly supplying Chinese digital measuring instruments. In particular: a digital ampervoltmeter is a very simple device, affordable and displays quite accurate information data.

But for beginners, commissioning (connecting an ammeter voltmeter to the circuit) can be a problematic task, because the measuring device comes without documentation and not everyone can connect the wires quickly marked with color.

An image of one of the most popular voltammeters among homemade people is posted below,

this is a 100 volt/10 amp ammeter and comes with a built-in shunt. Many radio amateurs often purchase such measuring instruments for their homemade products. The digital device can be powered both from separate sources,

and from one operated and measured voltage source. But here a small nuance is hidden, it is necessary to observe the condition - the voltage of the power source used was within 4.5-30 V.

For DIYers who are not yet entirely clear: we connect a thick black wire to the minus of the power supply, a thick red wire to the plus of the power supply (the readings of the voltmeter scale will light up),

we connect the thick blue wire to the load, the second end from the load comes to the plus of the power supply (the readings of the ammeter scale will light up).