This article is intended for people who can quickly distinguish a transistor from a diode, know what a soldering iron is for and which side to hold it by, and have finally come to the understanding that without a laboratory power supply their life no longer makes sense...
This diagram was sent to us by a person under the nickname: Loogin.
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Here I will try to explain in as much detail as possible - step by step how to do this with minimal costs. Surely everyone, after upgrading their home hardware, has at least one power supply lying under their feet. Of course, you will have to buy something in addition, but these sacrifices will be small and most likely justified by the end result - this is usually about 22V and 14A ceiling. Personally, I invested $10. Of course, if you assemble everything from the “zero” position, then you need to be prepared to shell out about another $10-15 to buy the power supply itself, wires, potentiometers, knobs and other loose items. But, usually, everyone has a lot of such rubbish. There is also a nuance - you will have to work a little with your hands, so they should be “without displacement” J and something similar may work out for you:
First, you need to get hold of an unnecessary but serviceable ATX power supply unit with a power >250W by any means necessary. One of the most popular schemes is Power Master FA-5-2:
I will describe the detailed sequence of actions specifically for this scheme, but all of them are valid for other options.
So, at the first stage you need to prepare a donor power supply:
- Remove diode D29 (you can just lift one leg)
- Remove jumper J13, find it in the circuit and on the board (you can use wire cutters)
- The PS ON jumper must be connected to ground.
- We turn on the PB only on a short time, since the voltage at the inputs will be maximum (approximately 20-24V) Actually, this is what we want to see...
Don't forget about the output electrolytes, designed for 16V. They might get a little warm. Considering that they are most likely “swollen”, they will still have to be sent to the swamp, no shame. Remove the wires, they get in the way, and only GND and +12V will be used, then solder them back.
5. Remove the 3.3 volt part: R32, Q5, R35, R34, IC2, C22, C21:
6.
Removing 5V: Schottky assembly HS2, C17, C18, R28, or “choke type” L5
7.
Remove -12V -5V: D13-D16, D17, C20, R30, C19, R29
8.
We change the bad ones: replace C11, C12 (preferably with a larger capacity C11 - 1000uF, C12 - 470uF)
9.
We change the inappropriate components: C16 (preferably 3300uF x 35V like mine, well, at least 2200uF x 35V is a must!) and resistor R27, I advise you to replace it with a more powerful one, for example 2W and take the resistance 360-560 Ohms.
We look at my board and repeat:
10.
We remove everything from the legs TL494 1,2,3 for this we remove the resistors: R49-51 (free the 1st leg), R52-54 (... the 2nd leg), C26, J11 (... the 3rd leg)
11.
I don’t know why, but my R38 was cut by someone and I recommend that you cut it too. It participates in voltage feedback and is parallel to R37. Actually, R37 can also be cut.
12. we separate the 15th and 16th legs of the microcircuit from “all the rest”: for this we make 3 cuts in the existing tracks and restore the connection to the 14th leg with a black jumper, as shown in my photo.
13.
Now we solder the cable for the regulator board to the points according to the diagram, I used the holes from the soldered resistors, but by the 14th and 15th I had to peel off the varnish and drill holes, in the photo above.
14.
The core of loop No. 7 (the regulator's power supply) can be taken from the +17V power supply of the TL, in the area of the jumper, more precisely from it J10. Drill a hole into the path, clear the varnish and go there! It is better to drill from the print side.
This was all, as they say: “minimal modification” to save time. If time is not critical, then you can simply bring the circuit to the following state:
I would also advise changing the high-voltage condensers at the input (C1, C2). They are of small capacity and are probably already pretty dry. There it will be normal to be 680uF x 200V. Plus, it’s a good idea to redo the L3 group stabilization choke a little, either use 5-volt windings, connecting them in series, or remove everything altogether and wind about 30 turns of new enamel wire with a total cross-section of 3-4mm 2 .
To power the fan, you need to “prepare” 12V for it. I got out this way: Where there used to be a field-effect transistor to generate 3.3V, you can “settle” a 12-volt KREN (KREN8B or 7812 imported analogue). Of course, you can’t do it without cutting tracks and adding wires. In the end, the result was basically “nothing”:
The photo shows how everything harmoniously coexisted in the new quality, even the fan connector fit well and the rewound inductor turned out to be quite good.
Now the regulator. To simplify the task with different shunts out there, we do this: we buy a ready-made ammeter and voltmeter in China, or on the local market (you can probably find them from resellers there). You can buy combined. But we must not forget that their current ceiling is 10A! Therefore, in the regulator circuit it will be necessary to limit the maximum current at this mark. Here I will describe an option for individual devices without current regulation with a maximum limitation of 10A. Regulator circuit:
To adjust the current limit, you need to replace R7 and R8 with a 10 kOhm variable resistor, just like R9. Then it will be possible to use the all-measures. It's also worth paying attention to the R5. IN in this case its resistance is 5.6 kOhm, because our ammeter has a 50mΩ shunt. For other options R5=280/R shunt. Since we took one of the cheapest voltmeters, it needs to be modified a little so that it can measure voltages from 0V, and not from 4.5V, as the manufacturer did. The whole alteration consists in separating the power and measurement circuits by removing diode D1. We solder a wire there - this is the +V power supply. The measured part remained unchanged.
The regulator board with the arrangement of elements is shown below. The image for the laser-iron manufacturing method comes as a separate file Regulator.bmp with a resolution of 300dpi. The archive also contains files for editing in EAGLE. Latest off. The version can be downloaded here: www.cadsoftusa.com. There is a lot of information about this editor on the Internet.
Then we screw the finished board to the ceiling of the case through insulating spacers, for example, cut from a used lollipop stick, 5-6 mm high. Well, don’t forget to make all the necessary cutouts for measuring and other instruments first.
We pre-assemble and test under load:
We just look at the correspondence of the readings of various Chinese devices. And below it is already with a “normal” load. This is a car main light bulb. As you can see, there is almost 75W. At the same time, do not forget to put an oscilloscope in there and see the ripple of about 50 mV. If there is more, then we remember about the “large” electrolytes on the high side with a capacity of 220uF and immediately forget after replacing them with normal ones with a capacity of 680uF, for example.
In principle, we can stop here, but in order to give more nice view device, so that it does not look 100% homemade, we do the following: we leave our den, go up to the floor above and remove the useless sign from the first door we come across.
As you can see, someone has already been here before us.
In general, we quietly do this dirty business and begin to work with files of different styles and at the same time master AutoCad.
Then we sharpen a piece of three-quarter pipe using emery and use enough soft rubber required thickness cut them out and use superglue to sculpt the legs.
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As a result, we get a fairly decent device:
There are a few things to note. The most important thing is not to forget that the GND of the power supply and the output circuit should not be connected, so it is necessary to eliminate the connection between the case and the GND of the power supply. For convenience, it is advisable to remove the fuse, as in my photo. Well, try to restore as much as possible the missing elements of the input filter, most likely the source code does not have them at all.
Here are a couple more options for similar devices:
On the left is a 2-story ATX case with all-in-one hardware, and on the right is a heavily converted old AT computer case.
The long-term construction is finally over! And now you can see a full-fledged multi-channel laboratory power supply.
Laboratory power supply housing
The first task was to make the case. The idea of purchasing a plastic case for REA quickly disappeared due to high cost on him with these dimensions. Well, the toad is strangling to pay more than a thousand for a piece of plastic. Therefore, it was decided to use 6 mm foamed PVC.
We cut PVC to the required dimensions:
Let’s imagine what it will look like and mark it out:
On front side We mark and make holes for the display elements, voltage regulation and terminals.
We glue the body and try on the transformer.
Transformer TSA-70-6, but rewound to suit your needs
On one part it produces 25 volts 0.6 A, on the other part bipolar power supply +15 volts 0 - 15 volts 0.6 A. I don’t remember the winding data, but it’s not difficult to calculate.
Internals of a laboratory power supply
Maybe someone has already understood what parts the power supply is assembled from; those who don’t understand or don’t know are already assembled boards for single-polar and bipolar power supplies from previous articles:
The source board is based on KR142EN12 and KR142EN18.
Unipolar source board based on KR142EN12
For assembly and configuration of these blocks with circuits and printed circuit boards, see separate articles.
We continue the assembly. DSN-DVM-368 was used. I have already written about them. Miniature and fully working indicators.
First start.
Then we connect everything else. And we get chaos from the wires.
The top view shows that another power supply is installed for the digital indicators of the voltmeters. It was not possible to power it from ready-made power supplies because the indicators have the same common minus and minus measurements, which will not allow taking correct readings.
Everything fell into place.
We tidy up a little and cut off the excess.
To make it more convenient to use, I decided to design the front panel. I made it in CDR and laminated it
Now the assembly is complete and you can use it
What we end up with:
2 independent adjustable channels
Possibility of parallel or serial connection of channels
1 channel bipolar:
15 V per polarity
current 0.6 A
Channel 2 unipolar
Indication: 3-digit LCD displays for current and voltage simultaneously
Post Views: 396
In the previous article we made a printed circuit board and soldered the main parts onto it, and today we will “sculpt” the case for our power supply.
Of course, I don’t pretend to be original, since I made the cases for my designs according to ready-made drawings, and if possible, I always tried to pack my designs into ready-made cases with minimal alteration for myself, and therefore, too great experience I don’t have cases in invention.
Here I will tell you only the process of manufacturing the case and the possible arrangement of power elements on the front panel and on the base inside. And it’s up to you to make it exactly this way, in this sequence, and from such materials. Moreover, if you have a ready-made case, or you can assemble it yourself, then skip this part.
I have some left over from the renovation MDF panel and an aluminum corner, which I decided to use. First of all, we place the elements of the power supply on the future base in the way they will be located and so that there is easy access to them.
We cut off the excess.
On the base, we must indicate the sides: “front”, “back”, “left” and “right”.
Mark and cut off a piece for the front wall.
Cut off a corner. Make the length of the corner 2-4 mm shorter than the length of the body wall.
Now let's dock front part housing from the bottom.
To ensure that the holes between the aluminum and wooden parts match perfectly, we proceed as follows: mark the first hole on the front wall, then apply the corner as it should be fixed, and firmly squeeze both parts. We go through with a thin drill wooden part through, punching a hole in the corner (left side of the picture).
To fasten the parts, I used bolts and nuts with a diameter of M3, respectively, and drilled the holes with a drill with a diameter of 3 mm.
We drill out all the holes on the front and rear walls of the case with a larger diameter drill to a truncated cone so that the screw head can hide in it. I drilled with a drill with a diameter of 8mm.
Now we install the aluminum corner in place, align it along the wall, and thin drill punch the second hole. We also drill this hole to a 3mm diameter, and use a screw and nut to fasten the second side of the front wall and the corner.
All other parts of the body are assembled together in the same way.
See the pictures below for the assembly process.
To fasten the top and side walls of the case we will make a threaded connection.
Using a thin drill, we go right through the wooden part and punch a hole in the corner. But now we drill a hole in the corner with a drill with a diameter of 2.5 mm, and use an M3 tap to cut the thread.
To fasten the top and side walls, select bolts with beautiful heads, since we will not hide these bolts.
There should be a box like this somewhere.
Now on the front wall we mark places for a voltmeter, a switch, a variable resistor and a block for the output voltage.
The largest part is the voltmeter, so we mark and cut it out first, and then we place all the other elements of the front wall relative to it. It is convenient to mark and draw a circle with a caliper.
Using a thick drill we go in a circle, and with a round file we adjust the hole for the voltmeter.
The next step is to mark the location of the block from which the output voltage will be taken. Your pad may be different from mine.
Place the toggle switch to turn on the power supply above the block.
For the variable resistor we make a special mount that will be attached to the base of the case. Here I used a part from a children's construction set.
And the last thing to do to finish the rough and dirty work is to drill ventilation holes in the base of the case under the transformer, radiator and in the back cover of the case.
Now it is advisable to close the screw heads on the front and rear walls of the case.
Here you can use factory-made wood putty, or you can collect sawdust from an MDF panel, mix it with PVA glue until it reaches the consistency of thick sour cream, and seal the holes with a spatula.
We let it dry for twelve hours and remove the excess with fine sandpaper, and if there are any rough spots left, then we again dilute the sawdust with glue, but to the consistency of liquid sour cream, and fill in all the rough edges.
Once it’s all dry, we go over it again with fine sandpaper and start painting.
I chose the paint in spray cans, since it dries quickly, there is no need to use a brush, and it goes on smoothly. The front panel will white, and everything else is black. It is advisable to paint in the fresh air.
Now we are gradually putting the power supply in order.
On the front panel we insert a milliammeter, a switch, a block for the output voltage and a variable resistor slider.
I put the block on glue, and with reverse side The front panel bent the contact petals for strength.
On the base I attached a transformer, a radiator, a board and a variable resistor.
Let's finish here, and in part we will calibrate the voltmeter scale and finally assemble the power supply. And if your transformer has a voltage on the secondary winding of more than fourteen volts, then you will learn how it is possible to further increase the output voltage of the power supply by 3 - 5 volts.
Good luck!
A short overview of the device housing for programmable power supply modules RD type DPS5005/DPS5015
There will be assembly, some photos of what happened.
Finally received the long-awaited package with a metal case for my DPH3205 (or DPS5015) power supply module.
This is a case ordered from Ruideng Technologies (RD) (with a discount that the seller gives on the next product for reviewing the purchase on YouTube). 
Case dimensions approximately 130x120x50 mm. 
The housing is suitable for both single display modules and modules with a power card. Just pay attention to this when ordering (different configurations, the seller adds fasteners for the board inside and drills holes. You can buy an economy version and do everything yourself, but the difference of $1 is not worth it) 
The case is universal, can be used for DPS5005 together with a powerful Lipo battery 
As a matter of fact, I initially chose it in chipidip and similar stores. This is a standard case, for which you will either need to cut a complete panel according to the dimensions of the module or make it yourself. 
The price is about 600 rubles plus delivery for a standard plastic case. And taking into account the discount for the previous order, the cost of mine was not much more expensive. In the end I chose it.
So, the case came in a foam box, wrapped in soft packaging. 
Inside is a neatly packaged instrument case from RD (flat, gray) with free crocodiles (GIFT is written on the package) 
The case is heavy, plus a fairly large kit designed for mounting programmable DPS/DPH/DP modules. The set weighs just under 450 grams. 
But the body profile itself without panels weighs 290 grams. Take this into account. That is, the version of the power supply without a battery, without an external power source and on modules like DPS5005 will weigh about 300g, but the version with DPS5015 is already approaching 400g plus an external source. 
The body consists of profiled metal (aluminum extrusion) halves, which are inserted into one another along a special groove. Some instrument cases for power electronics (for example, car inverters) are made according to this scheme, where cooling is required and the case simultaneously plays the role of a radiator.
There is a profile fin for heat dissipation. 
And this is what lay inside the case. These are two panels, crocodiles, mounting printed circuit board, fan, toggle switch, sockets and other terminals (4 mm plugs, 5 pcs). 
Housing delivery set. There are even wires of the required length (2.5 sq mm), silicone legs, and a power switch. 
And here appearance metal panels. Everyone is present required holes and nothing needs to be modified 
Trying on the DPS5005 panel 
Power converter board up to 5V for fan. It is also a circuit board for connecting power sockets and wires from the On-Off switch. 
Complete fan 40x40, attention, 5V. The cord is quite long, I don’t even know what it’s for. Possible for a second body (versatility). In theory, you need to either cut it to size, according to the location, or solder a similar socket into the board. 
Assembling both body panels 
Glue the silicone feet to the lower half of the body 
We cut, strip and crimp the wires. I apologize in advance for the glamorous background for the photo. 
We install the power module (large board with a controller) for DPS5015 or DPH3205.
Pictured is DPH3205 
This photo shows the “trying on” of DPS5015 
We assemble the body, or rather, we slide the halves into one another along the slide 
Next you need to install both panels 
Here is a photo of the case with the module assembled 
Here is a photo of the included module 
Panel close-up 
More photos of the case
Complete photo 
Front view 
Another photo 
Looks very good 
It doesn’t fit on the back wall, as the terminals at the back get in the way. 
The seller has detailed video about the process of installing modules into the case
To connect an external power supply, as well as a load, I use a set of wires with banana terminals. 
Instead of conclusions.
The case is of high quality, although a little expensive. If we compare it with the same, the latter costs about $50, has a smaller V and A bit capacity, and does not have programmable presets or memory. But GOPHERT is almost twice as compact.
An external DC power supply GOPHERT is not required, it is powered by 220V. 
As a plus of my design: This is versatility, since I can connect any power source available, and after use, turn it off and return it to its place. In the case of the DPH3205, I can use a 6V power supply to get up to 32V. Another benefit of versatility: for $50 I can use the DPS5015 module and get performance levels