Digital voltage and current indication panel. Simple digital power supply. About printed circuit board

I present for your attention a proven scheme of a good laboratory power supply published in the Radio magazine No. 3, with a maximum voltage of 40 V and current to 10 A. The power supply is equipped with a digital display unit, with microcontroller control. The BP scheme is shown in Figure:

Description of the device. Optopara supports the voltage drop on the linear stabilizer approximately 1.5 V. If the voltage drop on the chip is increasing (for example, due to an increase in the input voltage), the Optocristone LED and, respectively, the phototransistor opens. Shi-controller turns off, closing the switching transistor. The voltage at the input of the linear stabilizer will decrease.

To increase stability, the R3 resistor is placed as close as possible to the DA1 stabilizer chip. Chokes L1, L2 - segments of ferrite tubes, attached to the conclusions of the valves of field transistors VT1, VT3. The length of these tubes is approximately half the output length. The L3 throttle is winding at two folded together ring magnetic cores K36x25x7.5 from the Permalloe MP 140. Its winding contains 45 turns that are wound into two wires PEV-2 with a diameter of 1 mm, laid evenly around the perimeter of the magnetic pipeline. The IRF9540 transistor is permissible to replace on IRF4905, and the IRF1010N transistor is on BUZ11, IRF540.

If you need with an output current exceeding 7.5 A, you need to add another DA5 stabilizer parallel to DA1. Then the maximum load current will reach 15 A. In this case, the L3 choke is wound with a harness consisting of four PEV-2 wires with a diameter of 1 mm, and increase the capacity of C1-SZ capacitors by about twice. Resistors R18, R19 are selected at the same heating of DA1 chip, DA5. Shi-controller should be replaced by another, allowing work at a higher frequency, for example, KR1156EU2.

Module of digital measurement of voltage and current Laboratory BP

The basis of the device is a microcontroller Pici6F873. On the DA2 chip, the voltage stabilizer is assembled, which is also used as exemplary for the built-in ADC microcontroller DDI. RA5 and RA4 port lines are programmed as ADC inputs for voltage and current measurement, respectively, A RA3 - to control field Transistor. The current sensor is the R2 resistor, and the voltage sensor is the resistive divider R7 R8. The current sensor signal enhances the DAI OU. 1. And the DA1.2 is used as a buffer amplifier.

Specifications:

• Voltage measurement, in - 0..50.
• Measuring current, a - 0.05..9.99.
• Protection thresholds:
• - by current. A - from 0.05 to 9.99.
• - by voltage. B - from 0.1 to 50.
• Power supply, in - 9 ... 40.
• Maximum current consumed, ma - 50.

Usually, a good laboratory supply unit has built-in devices - a voltmeter and an ammeter. The voltmeter allows you to accurately set the output voltage, and the ammeter will show the current through the load. In old laboratory power blocks were arrow indicatorsBut now there must be digital. Now the radio amateurs most often make such devices based on a microcontroller or ADC chip like KR572PV2, kr572pv5

But there are other microcircuits similar action. For example, there is a CA3162E chip, which is designed to create an analogue size meter with a result display on a three-digit digital indicator. The CA3162E microcircuit is an ADC with a maximum input voltage of 999 mV (at the same time, the readings "999") and a logic scheme that issues information about the result of the measurement in the form of three alternately changing binary-decimal four-digit codes on a parallel output and three outputs to survey the dynamic circuits. Indications. To get a complete instrument, add an decoder to work on the seven-segment indicator and the assembly of three seven depends on the output node scheme on the decoder and keys. Here uses LED indication on the scoreboard of three seven-segment indicators with common anodes. The indicators are included according to the dynamic matrix scheme, that is, all of their segment (cathode) conclusions are included in parallel. And for a survey, that is, sequential switching, common anode conclusions are used.

Fig.1 Now closer to the scheme. On the figure 1. The voltmeter scheme measuring voltage from 0 to 100V (0 ... 99.9V) is shown. The measured voltage enters the conclusions 11-10 (input) of the chip D1 through the divider on the R1-R3 resistors. Condenser SZ eliminates the effect of interference on the measurement result.
The R4 resistor establishes the instrument to zero, in the absence of input voltage and the R5 resistor, the measurement limit is set so that the measurement result corresponds to the real, that is, it can be said to be calibrated by the device.
Now about the outputs of the chip. The logical part of CA3162E is built on the logic of TTL, and the outputs also with open collectors. At the outputs "1-2-4-8", a binary-decimal code is formed, which periodically replaces, providing consistent data transmission of three discharges of the measurement result. If the TTL decoder is used, such as the KR514IM2, then its inputs are directly connected to these inputs D1, if the CMOS logic decryctor or MOP will be applied, then its inputs will be used to plus with the help of resistors. It will need to be done, for example, if instead of the KR514IID2 will be used the K176ID2 or CD4056 decoder.
The outputs of the decoder D2 through the current-brassing resistors R7-R13 are connected to the segment conclusions of the LED indicators H1-NH. The segment conclusions of all three indicators are connected together. The transistor keys of VT1-VT3 are used to survey indicators, the database of which commands are submitted from the H1-from the D1 chip. These conclusions are also made according to the open collector scheme. Active zero, therefore, transistors of the R-P-PR structure are used.


Fig.2Ammeter diagram is shown on figure 2.. The scheme is almost the same. Except for the entrance. Here instead of a divider costs the shunt on a five-time resistor R2 with a resistance of 0.1 from. With this shunt, the device measures the current to 10a (0 ... 9.99a). Installation on zero and calibration, as in the first diagram, is carried out by resistors R4 and R5.
By selecting other divisors and shunts, you can specify other measurement limits, for example, 0 ... 9.99v, 0 ... 999ma, 0 ... 999v, 0 ... 99.9a, it depends on the output parameters of the laboratory power supply, in which will be installed these indicators. Also, on the basis of these schemes, you can make an independent measuring device for measuring voltage and current (desktop multimeter). It should be noted that even using liquid crystal indicators, the device will consume a significant current, since the logical part of CA3162E is built on TTL logic. Therefore, a good device with autonomous nutrition Not sure it's going to happen. But the automotive voltmeter (Fig. 4) will be quite good.
Feed devices with constant stabilized voltage 5V. In the power supply, which they will be installed, it is necessary to provide for such a stress with a current at no lower than 150mA.

On the figure 3. The diagram of connecting the meters in the laboratory source is shown.
Now about the details. Perhaps the most difficult-supplied, these CA3162 chips. From the analogs, only NTE2054 is known to me. There may be other analogs that I do not know about.
With the rest much easier. As already mentioned, the output scheme can be made on any decoder and the corresponding indicators. For example, if the indicators are with a shared cathode, then the KR514IM2 is needed to replace on the CR514IM1 (the basement is the same), and the transistors VT1-VT3 drag down, connecting their collector to a minus power, and emitters to common cathodes of indicators. You can use CMOS logic decoders, tightening their inputs to the power plus with the help of resistors.
Now about establishing. In general, it is completely simple. Let's start with a voltmeter. First, the conclusions 10 and 11 d1 closed with each other, and the adjustment R4 will set zero testimony. Then, we remove the jumper, closing the conclusions 11-10 and connect to the terminals "Load" an exemplary device, for example, a multimeter-adjusting voltage at the source output, tighten the calibration of the device so that its readings coincide with the multi-meter testimony.
Next, establish an ammeter. At first, without connecting the load, adjust the resistor R5 set its testimony to zero. Now they need a constant resistor resistance 20 from and no lower than 5W. Install the voltage 10V on the power supply and connect this resistor as a load. Adjust R5 so that the ammeter showed 0.50 A.
You can perform calibration and an exemplary ammeter, but it seemed more convenient to me with a resistor, although of course the accuracy of the resistance resistance is very affected by the quality of calibration.
Fig.4
In the same way, a car voltmeter can be made. The diagram of such an instrument is shown on figure 4.. The scheme from shown in Figure 1 differs only in the input and power circuit. This device is now powered by the measured voltage, that is, measures the voltage coming to it as nourishing. The voltage from the on-board network of the car through the R1-R2-R3 divider enters the input of the D1 chip. The parameters of this divider are the same as in the diagram in Figure 1, that is, for measurement within 0 ... 99.9V. But in the car, the voltage is rarely more than 18V (more than 14.5V already a malfunction). And rarely falls below 6V, unless falling to zero full disabling. Therefore, the device really works in the interval of 7 ... 16V.
Power 5V is formed from the same source using the A1 stabilizer section.

Many already know that I feed weakness to all kinds of power supplies, here is two in one. This time there will be an overview of the radio constructor, which allows you to collect the basis for the laboratory power supply unit and the option of its real implementation.
I warn you, there will be many photos and text, so reserve coffee :)

For a start, I will explain a little what it is and why.
Almost all radio amateurs use such a thing in their work as laboratory block Nutrition. Whether it is complicated with software control or very simple on LM317, but it still performs almost the same thing, nourishes different loads in the process of working with them.
Laboratory power supplies are divided into three main types.
With impulse stabilization.
With linear stabilization
Hybrid.

The first to have a pulse controlled power supply in their composition, or simply pulse block Power supply with lowering PWM converter. I have already overlooked several variants of these power supplies. .
Advantages - high power with small dimensions, excellent efficiency.
Disadvantages - RF ripples, the presence of capacious capacitors at the output

The second does not have any PWM transducers aboard, all adjustment is carried out by a linear way, where the excess energy is simply dispersed on the adjusting element.
Pluses are almost complete absence of pulsations, there is no need for condensers at the exit (almost).
Cons - efficiency, mass, envelope.

Third are the combination of either the first type with the second, then linear stabilizer It feeds on the slave-lowering of the converter (the voltage at the PWM of the converter is always supported at a level slightly higher than the output, the rest is regulated by the transistor operating in linear mode.
Either this is a linear BP, but the transformer has several windings that switched as needed, thereby reducing the losses on the adjusting element.
The minus this scheme is only one, complexity, it is higher than that of the first two options.

Today we will talk about the second form of power supplies, with a regulating element operating in linear mode. But consider this power supply on the example of the designer, it seems to me that it should be even more interesting. After all, in my opinion this is a good start for a novice radio amateur, collect yourself one of the main appliances.
Well, or as they say, the correct power supply must be heavy :)

This review is more focused on beginners, experienced comrades are unlikely to find something useful in it.

I ordered a constructor for review, which allows you to assemble the main part of the laboratory power supply unit.
The main characteristics are such (from the stated shop):
Input voltage - 24 volts alternating current
Output voltage adjustable - 0-30 volts direct current.
Output current adjustable - 2ma - 3a
Pulsation output voltage - 0.01%
Printing size - 80x80mm.

A little about packaging.
The designer came in the usual polyethylene package, closed into a soft material.
Inside in an antistatic package with a latch, all the necessary components lay, including a printed circuit board.

Inside everything was a mound, but at the same time did not suffer, the printed circuit board partially protected the radio components.

I will not list everything that is included, it's easier to do it later along the review, I will just say that I just had enough, even something left.

A little about pCB.
The quality is excellent, the scheme in the kit does not go, but all the rates on the board are indicated.
The board is double-sided, covered with a protective mask.

Coverage of fees, tinning, and the quality of the textolite is excellent.
I got only in one place to tear the patch with the print, and then after I tried to have a non-rigid detail (why, it will be further).
In my opinion the most that for a novice amateur, spoil will be hard.

Before installation, I figured the diagram of this sides.

The scheme is quite thoughtful, although not without flaws, but will tell about them in the process.
The scheme looks through several main nodes, I separated them by color.
Green - adjustment knot and stabilization
Red - adjustment knot and current stabilization
Violet - node indicating the transition to current stabilization mode
Blue - source of reference voltage.
Separately there:
1. Entrance diode bridge and filter condenser
2. Silence control unit on VT1 and VT2 transistors.
3. Protection on the VT3 transistor, turning off the output while power operating amplifiers Will not normal
4. Fan power stabilizer, built on a 7824 microcircuit.
5. R16, R19, C6, C7, VD3, VD4, VD5, a node for forming a negative power supply pole of operating amplifiers. Due to the presence of this node, the BP will not work simply from DC, it is necessary that the AC input from the transformer is necessary.
6. C9 output capacitor, VD9, output protective diode.

First, silent the advantages and disadvantages of the circuit solution.
Pros -
Pleases the presence of a stabilizer to power the fan, but the fan is needed for 24 volts.
Very pleases the presence of a power source of negative polarity, it greatly improves the operation of BP on currents and stresses close to zero.
In view of the presence of a negative polarity source in the circuit, protection has been protected, until this voltage, the BP output will be disconnected.
BP contains a source of a support voltage 5.1 volt, this allowed not only correctly adjusting the output voltage and current (with such a scheme, the voltage and current are adjusted from zero to a maximum of linearly, without "humps" and "failures" in extreme values), and allows you to manage Power supply from the outside, simply changing the control voltage.
The output capacitor is a very small container, which allows you to safely check the LEDs, there will be no current throw until the output capacitor is discharged and the BP will not enter the current stabilization mode.
The output diode is necessary to protect BP from feeding the reverse polarity voltage to its output. True diode is too weak, it is better to replace to another.

Minuses.
The current-measuring shunt has too high resistance, because of this, when operating with a load current, 3 amps is released about 4.5 watt heat. The resistor is designed for 5 watts, but heating is very large.
The input diode bridge is dialed out of 3 amp diodes. According to good, there should be diodes at least 5 amps, since the current through diodes in such a scheme is 1.4 from the weekend, respectively, in the operation of the current through them there may be 4.2 amps, and the diodes themselves are calculated for 3 amps. It makes it easier for the situation that pairs of diodes in the bridge work alternately, but still it is not entirely right.
Large minus is that Chinese engineers, when selecting operating amplifiers, chose OU with a maximum voltage of 36 volts, but did not think that the diagram was the source of the negative voltage and the input voltage in this version is limited at 31 volts (36-5 \u003d 31 ). With input 24 volts of alternating current, the constant will be about 32-33 volts.
Those. OU will work in the exhaust mode (36 is maximum, regular 30).

I will also talk about the pros and cons, as well as about modernization later, and now I will go to the assembly itself.

To begin with, lay out everything that is included. This will facilitate the assembly, and it will simply be clearly seen that they have already installed, and what else remains.

I recommend starting an assembly from the lowest elements, as if you first set high, then the low then it will be inconvenient to put.
It is also better to start with the installation of those components that are more identical.
I will start with resistors, and it will be resistors with a par 10 com.
Resistors are qualitative and have accuracy of 1%.
A few words about resistors. Resistors have color labeling. This may seem uncomfortable. In fact, it is better than diguristic labeling, since the marking is visible in any position of the resistor.
It is not necessary to scare the color marking, at the initial stage you can use, and eventually it will be possible to determine it already without it.
For understanding I. convenient work With such components, you only need to remember two things that the novice radio amateur will be useful in life.
1. Ten basic marking colors
2. Nominal ratios, they will not be much useful when working with accurate resistors of the E48 and E96 resistors, but such resistors are much less common.
Any radio amateur with experience lists them simply by memory.
1, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.7, 3, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1.
All other denominations are multiplying these 10, 100, etc. For example, 22k, 360k, 39.
What gives this information?
And it gives that if a resistor of a series of E24, then for example, a combination of colors -
Blue + green + yellow in it is impossible.
Blue - 6.
Green - 5.
Yellow - x10000.
those. According to the calculations, there are 650K, but there is no such nominal in series of E24, there are either 620 or 680, it means that either the color is not recognized, or the color is changed, or the resistor is not a series of E24, but the latter is rare.

Well, enough theory, let's go further.
The conclusions of the resistors before installing I form, usually using a tweezers, but some use a small homemade device for this.
Cutting outputs are not in a rush, it happens that they can come in handy for jumpers.

By installing the main amount I reached single resistors.
It may be harder here, it will be more often.

I don't immediately solder the components, but I just bite and bend the conclusions, and we first webly, and then bend.
It is done very easily, the board holds in the left hand (if you are right-hand), the installed component is pressed at the same time.
In the right hand, there are side handers, we bite the conclusions (sometimes even several components at once), and the side of the side of the windings immediately bend the conclusions.
It all is done very quickly, after a while already on automation.

So they reached the last small resistor, the nominal value of the required and what remains coincides, is not bad :)

By installing resistors proceed to diodes and stabilion.
Small diodes here are four, these are popular 4148, Stabilians two at 5.1 Volta each, so it's very difficult to get confused.
They also formulate conclusions.

The cathode is marked with a strip, as well as on diodes and stabilods.

At least a fee and has a protective mask, but I still recommend bending the conclusions so that they do not fall on nearby walkways, in the photo the withdrawal of the diode will benthered away from the track.

Stabilians on the board are also marked as marking on them - 5V1.

Ceramic capacitors in the scheme are not very much, but their marking can confuse a novice radio amateur. By the way, it also obeys the number of E24.
The first two digits - nominal in picofarades.
The third digit is the number of zeros to add to the nominal
Those. for example 331 \u003d 330pf
101 - 100pf
104 - 100000 PF or 100 NF or 0.1MKF
224 - 220000PF or 220NF or 0.22MKF

The bulk of passive elements is established.

After that, go to the installation of operating amplifiers.
I guess I would recommend buying panels to them, but I fell as it is.
On the board, as well as on the chip itself, the first conclusion is marked.
The remaining conclusions are considered counterclockwise.
The photo shows a place for an operational amplifier and how it should be put.

In the chips, I'm not all conclusions, but only a couple, usually this is the extreme conclusions on the diagonal.
Well, it is better to bite them so that they stick to about 1mm above the board.

Everything, now you can go to the soldering.
I use the most ordinary soldering iron with temperature control, but quite enough and the usual soldering iron with a capacity of about 25-30 watts.
Solder diameter 1mm with flux. I specifically I do not specify the solder brand, since on the coil of a non-rigid solder (the native coils 1kg weighing), and the name of it is not familiar to him.

As I wrote above, the board is high-quality, it rolls very easily, no fluxes I applied, enough only what is in the solder, you just need to not forget sometimes shaking an extra flux with sting.

Here I made a photo with an example of a good soldering and not very.
A good soldering should look like a small droplet enveloping output.
But in the photo there are a couple of places where the solder is clearly not enough. This will be held on a double-sided platter with metallization (there the solder is also in the hole in the hole), but it cannot be done on a one-sided board, with time such a soldering can "fall off".

Transistor's conclusions should also be previously defined, it is necessary to do this so that the output is not deformed near the base of the body (Aksakala will recall the legendary CT315, which believed the conclusions to be laid out).
Powerful components I form a little different. Molding is made so that the component stood over the board, in this case the heat will be less transmitted and it will not destroy it.

This looks the molded powerful resistors on the board.
All components soldered only from the bottom, the solder that you see on the top of the board penetrated through the hole due to the capillary effect. It is advisable to solder so that the solder penetrates a little on the upper part, it will increase the reliability of the soldering, and in the case of heavy components, their better stability.

If before this conclusions of the components, I molded with a pincelet, then small pliers with narrow sponges will already be needed for diodes.
Form conclusions as well as the resistors.

But when installing there are differences.
If the components with subtle conclusions first take place, then bite, then the diodes are the opposite. You simply do not drive such a conclusion after biting, therefore, we first begin the conclusion, then we are biting superfluous.

The power node is assembled using two transistors included according to the Darlington scheme.
One of the transistors is installed on a small radiator, better through the thermal paste.
In the kit there were four screw M3, one goes here.

Couple photo of almost soldered board. I will not paint the terminal workers and other components, it is intuitive, and it can be seen by photography.
By the way, about the terminalnikov, the board has terminal blocks to connect the input, output, fan power supply.

I have not yet rinsed the fee, although I often do it at this stage.
It is due to the fact that there will be another small part of the revision.

After the main assembly stage, we left the following components.
Powerful transistor
Two variables of the resistor
Two connectors for installation on the fee
Two connectors with wires, by the way, the wires are very soft, but a small cross section.
Three coils.

Initially, the manufacturer conceived to place variable resistors on the board itself, but so they are as inconvenient that I did not even solder them and showed just for example.
They cost very close and regulate will be extremely uncomfortable, although really.

But thanks for not forgotten to give a wire with connectors, it is much more convenient.
In such a form, the resistors can be taken to the front panel of the device, and install the fee in a convenient location.
Along the way spared a powerful transistor. This is usual bipolar transistorbut having a maximum dispel power up to 100 watts (naturally when installed on the radiator).
There are three screws left, I did not understand where to even apply them if at the corners of the board, then you need four if you fix a powerful transistor, then they are short, in general a riddle.

You can feed the board from any transformer with output voltage up to 22 volts (in the characteristics stated 24, but I explained the above why this voltage cannot be applied).
I decided to use a long-lying transformer for a romance amplifier. Why for, not from, but because he has not yet stood anywhere :)
This transformer has two second-volt power windings, two auxiliary 16 volts and shielding winding.
The voltage is indicated for the input 220, but since we now have a standard 230, then the output voltages will be slightly higher.
The calculated transformer power is about 100 watts.
Weekend power windings I rang up to get more current. You could certainly use a straightening scheme with two diodes, but it will not be better with her, therefore left as it is.

For those who do not know how to determine the power of the transformer, I took off a small video.

First trial inclusion. On the transistor, I installed a small radiator, but even in this form it was quite large heating, since the BP is linear.
Current and voltage adjustment occurs without problems, everything has earned immediately, because I have already completely recommended this constructor.
The first photo is the stabilization of the voltage, the second current.

For a start, I checked that it issues a transformer after straightening, as this determines the maximum output voltage.
I got about 25 volts, not thick. The capacity of the filter capacitor is 3300MKF, I would advise it to increase it, but even in this form, the device is perfectly operational.

Since it was necessary to apply a normal radiator for further check, then I switched to the assembly of a future design, since the radiator installation depended on the planned constructive.
I decided to apply IGLOO7200 lying radiator. According to the manufacturer's application, such a radiator is able to disperse up to 90 watts heat.

The device will be used the Z2A case in theory of Polish production, the price of about 3 dollars.

Initially, I wanted to move away from the chassis came from my readers, in which I collect all sorts of electronic things.
To do this, I chose a slightly smaller body and bought a fan with a mesh to it, but I did not turn into it all the filling and the second case was purchased and the second fan, respectively.
In both cases, I bought Sunon fans, I really like the products of this company, also in both cases bought fans for 24 volts.

So, on the idea, I had to install a radiator, a board and a transformer. There is even a little space on the expansion of the filling.
Turn the fan inside did not work in any way, because it was decided to place it outside.

Place the mounting holes, cut the thread, screw it for fitting.

Since the selected case has an internal height of 80mm, and the board also has such a size, then I secured the radiator so that the fee is obtained symmetrically with respect to the radiator.

The conclusions of the powerful transistor also need to be modified slightly so that they are not deformed when the transistor is pressed to the radiator.

A slight retreat.
The manufacturer for some reason was conceived a place to install a rather small radiator, because of this, when setting a normal, it turns out that the fan power stabilizer and the connector will interfere with it.
I had to fall out, and the place where they were, stuck with scotch, so that there was no connection with the radiator, since there is a voltage.

I cut extra tape from the opposite side, otherwise it turned out as it was completely inaccurarately, we will do on the flush :)

This looks like a printed circuit board with a finally installed radiator, the transistor is installed through the thermal colon, and it is better to apply good thermal plaistersince the transistor dispels the power comparable to powerful processor. about 90 watts.
At the same time, I immediately made a hole for installing the fan speed regulator board, which eventually had to reap :)

To set the zero and unscrewed both regulators to the leftmost position, turned off the load and set the zero at the output. Now the output voltage will be adjusted from zero.

Further a few tests.
I checked the accuracy of maintaining the output voltage.
Idling, voltage 10.00 volts
1. Load current 1 amp, voltage 10.00 volts
2. Load current 2 amps, voltage 9.99 volts
3. Load current 3 amps, voltage 9.98 volts.
4. Load current 3.97 amps, voltage 9.97 volts.
The characteristics are quite good, if you wish, you can still improve them by changing the connection point of resistors. feedback By voltage, but as for me, enough and so.

I also checked the level of ripples, the check took place at a current of 3 amps and 10 volts output voltage

The level of ripples amounted to about 15mB, which is very good, though thought that in fact the pulsation shown in the screenshot was rather diagnosed from an electron load than from the BP itself.

After that, I started assembling the device itself as a whole.
Started from installing a radiator with a power supply board.
To do this, I placed the installation site of the fan and power connector.
The hole was not completely round, with small "cuts" at the top and below, they are needed to increase the strength of the rear panel after cutting the hole.
The greatest complexity usually represent the holes of a complex form, for example, under the power connector.

A large hole is cut out of a big pile of small :)
The drill + drill with a diameter of 1mm sometimes creature wonders.
Drills holes, many holes. It may seem that it is long and tedious. No, on the contrary, it is very fast, the complete drilling of the panel takes about 3 minutes.

After that, I usually put the drill slightly more, for example, 1.2-1.3mm and I pass as a cutter, it turns out such a break:

After that, we in the hands of a small knife and cleaned the resulting holes, at the same time cut a little plastic if the hole was slightly smaller. Plastic is quite mild, therefore it is convenient to work.

The last stage of preparation drills the fasteners, one can say that the main work on back panel Finished.

We establish a radiator with a board and a fan, trying on the resulting result, if necessary, "we refund with a file".

Almost at the very beginning I mentioned refinement.
I will refine a little.
For a start, I decided to replace my native diodes in the input diode bridge on Schottky diodes, I bought four pieces 31dq06 for this. And then I repeated the error of the developers of the board, buying diodes on the inertia to the same current, and it was necessary for a greater. But still the heating of the diodes will be less, since the fall on Schottky diodes is less than on the usual.
In second place, I decided to replace the shunt. I was not satisfied not only that it was heated as an iron, but the fact that it falls about 1.5 volts, which can be used in the case (in the sense of the load). To do this, I took two domestic resistors 0.27 1% (it will also improve stability). Why did not make the developers, it is not clear, the price of solving is absolutely the same as in the variant with the native resistor at 0.47 Ohm.
Well, rather as an addition I decided to replace the native capacitor of the filter 3300MKF better and capacious Capxon 10000 μF ...

This is what the resulting design with replaced components and set payment Fan thermocontrolle.
It turned out a bit of collective farm, and besides, I accidentally threw one patch on the board when installing powerful resistors. In general, it was possible to calmly apply less powerful resistors, for example, one resistor for 2 watts, I just did not have this in stock.

Low components were also added below.
Resistor by 3.9K, parallel to the extreme connector contacts to connect the current adjustment resistor. It is needed to reduce the voltage of adjustment as the voltage at the shunt is now different.
A pair of capacitors by 0.22mkf, one in parallel to output from the current adjustment resistor, to reduce the tip, the second simply on the output of the power supply, it is not particularly needed, I just accidentally took out a couple immediately and decided to apply both.

The entire power part is connected to the transformer along the way, a board with a diode bridge and a capacitor to power the voltage indicator is installed.
By and large, this fee is optional in the current version, but to feed the indicator from the limit 30 volts for it. My hand did not rose and I decided to use an additional 16 volt winding.

The following components were used to organize the front panel:
Terms for connecting the load
A pair of metallic handles
Power switch
Red Light Filter, declared as a light filter for KM35 enclosures
To indicate the current and voltage, I decided to use the fee left after writing one of the reviews. But I was not satisfied with small indicators and therefore were bought larger with a number 14mm, and a printed circuit board was made to them.

At all this solution Temporary, but I wanted to even temporarily make carefully.

Multiple stages of front panel preparation.
1. Blacksmith in front of the front panel of the front panel (I use the usual lyaout sprint). The advantage of using the same enclosures is that it is very simple to prepare a new panel, since the necessary dimensions are already known.
We apply the printout to the front panel and in the corners of square / rectangular holes drills the marking holes with a diameter of 1mm. The same drill chop the centers of the rest of the holes.
2. According to the resulting holes, place the place of cut. We change the tool for a thin disc mill.
3. Slap straight lines, in front of it is clearly in size, the back is slightly more, so that the rubber was the most complete as possible.
4. We take out the cut slices of plastics. I usually do not throw them away, as they can still come in handy.

Similar to the preparation of the rear panel process the resulting holes with a knife.
I recommend drilling a large diameter, it does not "eat" plastics.

We try what we did, if necessary, we refirm with the help of the noer.
I had to slightly expand the hole for the circuit breaker.

As I wrote above, for the indication I decided to use the fee left from one of the past reviews. In general, this is a very bad solution, but for a temporary option more than a suitable, I will later explain why.
We drag out the indicators and connectors from the board, the old indicators and new ones are ringing.
I painted the Codoolevka of both indicators so as not to get confused.
In the native version four-digit indicators were applied, I applied three-bit. Since I did not have any more in the window. But since the fourth discharge is needed only to display the letter A or U, then their loss is not critical.
LED Display Limit Mode I placed between indicators.

I prepare everything you need, with an old board I drop out a resistor on 50mom, which will be used as before, as a toko-measuring shunt.
Here is a problem with this shunt and is associated. The fact is that in this version, I will have a voltage drop at a 50mw output for each 1 ampere of the current current.
You can get rid of this problem in two ways, apply two separate meters, for current and voltage, while drinking a voltmeter from a separate power source.
The second way is to establish a shunt in the positive Pole of BP. Both options were not suitable for a temporary solution, so I decided to step on my own perfectionism and make a simplified version, but far from the best.

For the design, I used the mounting racks remaining from the DC-DC converter board.
With them I got very comfortable designThe indicator board is attached to the ampervoltmeter board, which in turn is attached to the board of power terminals.
It turned out even better than I expected :)
Also on the board of the power terminals, I placed a toko-measuring shunt.

The resulting design of the front panel.

And then I remembered that I forgot to establish a more powerful protective diode. I had to dope it later. I used the diode left after replacing diodes in the input bridge of the board.
Of course, for a good need to add a fuse, but this is not in this version.

But the current and voltage adjustment resistors I decided to put better than those that offered the manufacturer.
Natives are quite high-quality, and have a smooth move, but these are ordinary resistors and as for me a laboratory power supply must be able to more accurately adjust the output voltage and current.
Even when I thought to order a BP fee, I saw in the store and ordered a review and them, especially since they had the same nominal.

In general, I usually apply other resistors for such purposes, they combine two resistors at once, for coarse and smooth adjustment, but in lately I can not find them on sale.
Can someone know their imported analogues?

Resistors are quite high-quality, angle of rotation of 3600 degrees, or by simple - 10 full revolutions, which ensures the rearrangement of 3 volts or 0.3 amps by 1 turnover.
With such resistors, adjustment accuracy is approximately 11 times more accurate than normal.

New resistors in comparison with relatives, the envelope is certainly impressive.
Along the way, I have a little rooted wire to resistors, it should improve noise immunity.

She packed everything into the case, in principle there was even a little place left, there is where to grow :)

I connected the shielding winding with the grounding conductor connector, board additional nutrition Located right on the terminals of the transformer, it is certainly not very neat, but I have not yet invented another option.

Check after assembly. It all started almost the first time, I accidentally confused two discharge on the indicator and could not understand that it was not so adjustable, after switching everything became as it should.

The last stage is the inclination of the light filter, the installation of the handles and the assembly of the case.
The light filter has a thinning around the perimeter, the main part is interinted into the window window, and a more subtle part is glued with double-sided tape.
The handles were initially calculated under the diameter of the shaft of 6.3mm (if not confused), new resistors have thinner, it was necessary to wear a pair of layers of heat shrink.
The front panel I decided not yet to make it no matter and there are two reasons:
1. The management is so intuitive that there is no particular sense in inscriptions.
2. I plan to refine this power supply, because changes are possible in the front panel design.

Couple photo of the resulting design.
Front view:

Back view.
Attentive readers probably noticed that the fan is so that blows hot air from the housing, and does not pump cold between the risaries.
I decided to do so because the height radiator is slightly less housingAnd so that hot air does not get inside, I put the fan on the contrary. This of course, noticeably reduces the efficiency of heat removal, but allows you to slightly ventilate and the space inside the BP.
Additionally, I would recommend to make several holes from the bottom of the lower half of the hull, but it is rather an addition.

After all alterations, I turned out to be a little less than in the original version, and amounted to about 3.35 amps.

And so, I will try to spite the advantages and cons of this board.
pros
Excellent manufacturer quality.
Almost proper circuitry of the device.
Full set of details for assembling power supply stabilizer board
Well suits novice radio amateurs.
In minimal form, only a transformer and radiator also requires, in a more expanded ampervoltmeter.
Fully workable after assembly, albeit with some nuances.
The absence of capacious capacitors at the output of BP is safe when checking LEDs, etc.

Minuses
The type of operating amplifiers is incorrectly selected, due to this, the input voltage range must be limited to 22 volts.
Not very suitable summary of the current measurement resistor. It works in a normal thermal mode for him, but it is better to replace it, as heating is very large and can harm the surrounding components.
The input diode bridge operates at a maximum, it is better to replace diodes to more powerful

My opinion. In the process of assembly, I had the impression that the scheme was developed two different people, one applied the correct control principle, the source of the reference voltage, the source of the negative polarity, protection. The second incorrectly chosen the shunt, operational amplifiers and the diode bridge under this.
I really liked the scheme engineering, but I first wanted to replace the operational amplifiers at first, I even bought microcircuits with a maximum working voltage of 40 volts, but then changed my mind. But the rest of the decision is quite correct, the adjustment is smooth and linear. The heating of course is, without him anywhere. In general, as for me, for a novice radio amateur, this is a very good and useful designer.
Surely there will be people who will write what is easier to buy ready, but I think that it is most likely to collect and more interesting (probably the most important thing) and more useful. In addition, many are quite calmly at home there is a transformer and radiator from the old processor, and some kind of box.

Already in the process of writing a review, I had even more feeling that this review would be the beginning in a series of reviews dedicated to the linear power supply, there are thoughts on refinement -
1. Transfer the indication and control circuit into a digital variant, possibly connecting to a computer
2. Replacing the operational amplifiers to high-voltage (I do not know what)
3. After replacing OU, I want to make two automatically switchable steps and expand the output voltage range.
4. Change the principle of measuring the current in the indication device so that there is no voltage drawdown under load.
5. Add the ability to disconnect the output voltage with the button.

That's probably all. Perhaps I still remember something and supplement, but I'm waiting for comments with questions.
Also in the plans to devote a few more reviews to designers for beginner radio amateurs, maybe someone will have suggestions about certain designers.

Not for the faint of heart

At first I did not want to show, but then I decided to make a photo yet.
On the left of the power supply that I enjoyed many years before.
This is a simple linear BP with a 1-1.2 amper exit at a voltage of up to 25 volts.
Here I wanted to replace it with something more powerful and correct.

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