» Electronics » Power supplies »Adjustable power supply - very simple, even a schoolboy can do. In detail

An adjustable power supply is very simple, even a schoolboy can do. In detail

And again, I am glad to welcome You Dear master friends!



Today, I want to talk with you about old and seemingly worthless dusting in the corner of an apartment or the garagecompleting your old computer. In particular, about an old computer power supply unit, not working people in your eyes, but still issuing its own 12V DC voltage.

The computer power supply, I can say with great confidence, is the perfect device for any master. From a computer power supply, you can make a good regulated source of constant voltage.

Today, the price of a laboratory power supply reaches ten thousand rubles. But, there is a good option, just remake the computer power supply into an adjustable laboratory power supply. Of course, it will not be so accurate, but it is quite suitable for the work of a home master. And it will cost YOU about 350-400 rubles. Having spent one and a half to two hours of your time, you will get a power supply for: 3.3 V, 5 V and an adjustable voltage of 12-35 Volts, a pretty decent power.

Adjustable power supplies are good in that they enable the master, the master, and simply the consumer, to regulate the output voltage. Such power supplies can be used for various purposes, for example: for checking incandescent lamps, LEDs, charging batteries and for powering various electrical and electronic devices in your workshop.

And to summarize, a power supply with voltage regulation at this modern stage is an absolutely necessary thing for any real man, with his hands growing not from n @ py. This simple device, due to its technical properties, can easily convert the voltage and current available in your electrical network to a level that is suitable for the consumption of a particular electronic device.

I want to offer a budget option for an adjustable power supply, as noted above, for accessories, it will cost you 350-400 rubles, agree 400 rubles is much less than 10 thousand.

This power supply, I’m sure, can be done by any novice master who has at least the idea that the current runs through the wires. In the article I will describe in detail the manufacturing process of the power supply, and if you are interested in this device, I will conduct detailed installation of all the wires and systems of this device in the video clip of the instruction.

The idea of ​​an adjustable power supply is very simple. Now in Chinese online stores appeared DC / DC converters. In our case, the boost converter with the declared power of 150 watts is taken as the basis. (Our Chinese friends, of course, as always overestimate these parameters, but there are probably 100 watts.), With a fixed power supply from 10 to 30V and an adjustable output voltage from 12 to 35V. Links to Aliexpress where you can purchase this converter and accessories for our power supply are available in the video clip.

Having powered this converter from our computer power supply unit with 12 volts of constant voltage, at the output we get an adjustable voltage of 12-35V. Also in the computer power supply there are fixed voltages 3.3V and 5V. We will also remove them on our device.

It has already become a tradition in our articles to talk a little about safety precautions. My advice to you: never check the availability of electricity in your tongue and you will have a wonderful Hollywood smile and a good, easily digestible speech. Do not stick your arms and legs in those places where the dog does not stick its tail, and you will still dance the gypsy and play the piano.
For safety, basically everything.

Getting to the production homemade.

In the beginning, for those who like to watch more than read, video clip instructions on how to make an adjustable power supply from an old computer unit:

Video clip of manufacturing a power supply:




Video clip connecting a multimeter DSN-VC288

100V and 10A (a detailed description of the ladies in a separate article):




Tools that are useful in the manufacture of our device:



1. Soldering iron.
2. Screwdrivers.
3. Drilling machine or drill.
4. Drills.
5. File or file.
5. Emery cloth.
6. Stationery knife.
7. Wrenches.
8. Measuring tool, at least a ruler.
9. Descriptive tool, pencil.
10. Kerner.
11. Pliers or pliers.
12. Cutting machine (grinder) with a cutting wheel and grinding.

Consumables Required:



1. Solder.
2. Soldering acid.
3. Bolts and nuts.
4. Installation wires.
5. Step-up voltage converter.
6. Voltammeter 100V, 10A.
7. Plugs, connectors and other trifles.
8. The switch.
9. Variable resistor.
10. Heat shrink tubes.

The procedure for manufacturing an adjustable power supply:






















1. Find an old, working computer power supply.
2. Open thoroughly but gently clean from accumulated dust and dirt.
3. To remove excess wires from the bundle, leave black minus power, yellow 12V plus, orange 3.3V plus, red 5V plus, and green to turn on the power supply.
4. On the front panel of the power supply, drill and drill holes for mounting control devices, control knobs and voltage relieving connectors from our device.
5. Solder the tuning resistor from the step-up voltage converter, solder a 10 kΩ variable resistor in its place.
6. Solder the wires of the power supply unit, it is shown in detail in the video clip, do not panic, everything is very simple, the main problem is not to burn your fingers with a soldering iron :-).
7. On the front panel, place and secure the multimeter, control knob, switch and voltage relieving connectors.
8. Connect the prepared wires to the multimeter, control knob, switch and relays.
9. Place and raise the step-up voltage converter connected to the power supply unit and fix it in our power supply unit. The full-time position is shown in the video.
10. Assemble the case of the resulting power supply.
11. Connect the power supply to the 220V network.
12. Click on the switch to turn on the device.
13. A voltage should be displayed on the multimeter.
14. Set up and test the regulated power supply under load.

Technical analysis:



Pros:

1. budget costs for component structures.
2.sufficient compactness.
3. Easy to manufacture.
4. Easy operation.

Minuses:

1. Insufficient accuracy of the device, from 10 mA.
2. The voltage is adjustable from 12V. 3.3 and 5V fixed voltage. But we are working on it.



That's all for today! Good luck to you!
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124 commentary
It was a deal. But once I decided to stop, just stopped, without any craving and dreams about the smoke. However, returning to the samosad, not everyone will be able to grow it now, and many already have no idea what it is and it's not just about youth.
Let’s increase the current 10 times, what we get ...
We get two banks of 470.0 X 400 V! And on your capacitors we get Xc = 135 Ohm,
Хс = 1 / ωС, where ω is the circular frequency equal to the product 2πf, С is the circuit capacity in farads
!
And the devil knows him smiles
Let us estimate: at almost 300 mA, the inclusion of 47.0 μF gives a drop of 3 mA, i.e. 1%, imperceptibly. Let’s increase the current 10 times, what we get ...
Oh well, Friday night and 10 times the problem drinks
ino53
Yes, the circuit works.
Interestingly, what capacitors are needed for currents of 2-3A? scratch
So many copies are broken, And religion doesn’t allow winding up the necessary secondary housing? Well, yes, it’s hard for ARDUIN to add it here! xaxa
brnjh1
I have not heard such a wonderful expression, I take it into service ...
It’s better to overeat than not to sleep, it’s better to sleep than not to eat, it’s better to be healthy and rich than poor and sick!
yes
R555
We got a capacitor with a capacity as one and dimensions like two
Get half the capacity of one capacitor! Total = C1 * C2 / (C1 + C2) nea
Author
Quote: Valery
I don’t want to quit!

As Mark Twain used to say - Quitting smoking is easy, how many times have I done it ...
2Dem
Soon there will be a choice to either eat or smoke ...
And you didn’t have to smoke a sediment?
Valery
I heard about some "swollen ears", that "I get up to smoke at night" ... I don’t have that
And I, unfortunately, already have it! I don’t smoke for more than an hour - my ears swell, I begin to have fun for no reason at all, at night I get up to smoke every 1.5 - 2 hours. I understand the air brawlers well, while flying, I am stocking up with all sorts of rubbish under my tongue, chewing ...
My friend quit smoking, coded with a grandmother of some kind, drove right into the neighboring region. I asked him that I began to take care of health? And he answered, no, it just became expensive to smoke.

He did not go to the grandmother alone, but as a whole crowd, I know many. So, from the smoke, the grandmother encoded them normally. It seems that only one resumed.

But, the old woman invited them to code for vodka - everyone refused flatly xaxa
Well yes.))))...
For the flood, Nikolai is not atrocious yet ...
Okay, good night .. Tomorrow morning drive far away ... (By the way, in Grodno)))
......
I envy, I had to go to be encoded when I began to crap with green muck. bad
In general, a cool discussion of homemade work turned out! xaxa
Come on ... Tell someone in the 90s that a pack of cigarettes will be an average of one and a half dollars !!! Everyone would say in a panic that they would definitely “then have to quit!” ... In the same way, we’ll adapt to five dollars! Look, all of Europe has been smoking for so long.)))
That's real ... I don’t have a "chemical dependence", although I have been smoking for 30 years !! I heard about some "swollen ears", that "I get up to smoke at night" ... I don’t have that.I never want to smoke, but often I want to smoke.)))). I am the absolute choleric! I can’t "stand still".))) I always have to do something! And so, "smoke" - this is exactly what may take for a while.
If I have something interesting to do - I do not light! (Then I feel sorry for this time!)))). I smoke a lot, when you need to think a lot - then it's good to sort out a cigarette in your fingers and look at the smoke.))) I always smoke with coffee. (I often drink coffee!) Purely because it is “tasty.”))) And while thinking something, again, it's good! ...
I do not like to go out with someone to smoke - why ?. You can just talk to him. And when you talk to someone - why NOT smoke? After all, there is some ACTION! And the smoking process, as an action - is not needed! (But in another way I do not need him))). Therefore, I always smoke alone. In a smoking company, often not smoking, I participate in a conversation. Then, when I was alone, I light a cigarette and think over the conversation.
I don’t want to quit! I like the process ..
I can! Checked. (For the sake of interest, I didn’t smoke for six months. I announced to the matchmakers that I’ll extinguish this cigarette, and I’ll smoke the next one on December 31, New Year. (It was June 2 — my DR). I didn’t smoke without much tension. Just, somehow .. It’s boring ... And I wanted exactly this ACTION - to Smoke. But this action had a result - a test, that means there was an incentive to “finish to the end” and the joy that it “easily and evenly” turns out. (It’s like in homemade products - when everything goes smoothly.))))
When I lit, the first time was "tasteless." Even a cough appeared and .... How would I explain ... I wanted to smoke (action), but it was very unpleasant to drag out ... It spun from cigarettes. I even thought that maybe during this time something has worked out with this variety? Type, changed the recipe. It was okay ... I had to again slowly get involved, because I didn’t want to drop it.
... Well, something like that ... Nicotine doesn’t catch me like a drug ... I don’t understand why.
The Russian government has taken care of you. They say expected +36 to excise duty after NY, which means a minimum of +50 in retail. Soon there will be a choice to either eat or smoke ... But smoking is easier to quit than it is)))
Author
Quote: R555
You don’t have to quit drinking

It’s easier to quit drinking, but smoking ... is a disaster.
Valery , the opposite is true. You don’t need to quit drinking, you don’t really drink. But smoking must be tied preved
And I also like to jokingly say that "I will smoke !!! But I will not give up drinking!"
Capacitors 47.0 * 400 V, KD247 diodes, in series with a 60 W lamp and a 1 Ohm resistor as a current-measuring shunt



Yes, the circuit works.
I have made non-polar from a polar (electrolyte) many times and I think that this will work both in the sound circuits of the amplifier and in the power supplies.

I will try to state the advantages and disadvantages of this method.

We take 2 electrolytes with the same capacitance and voltage and combine them plus to plus. The remaining 2 minuses will be the findings of the created non-polar capacitor.

Merits. Received a non-polar capacitor with doubled operating voltage.

Disadvantages. We got a capacitor with a capacity of one and dimensions like two.

Not very fun when it comes to capacitors in the power supply.
Author
Quote: Valery
Better to overeat than not to sleep !!!

I have not heard such a wonderful expression, I take it into service ... :-)))
Those. like this:

I don’t know, I don’t know how many times the guys in this scheme tried to start three-phase motors - without success.
(About starting cond. And others. Is not necessary)
I think the capacitors will be charged, but the diodes will not discharge, and they will stand. However, I’ll go to solder, turn on through the light bulbs described by me, and, if there is something interesting, take a picture.
.....
The author of this scheme used polar electrolytes per 100 volts (C3, C4), with a total of 40 volts in the shoulder. He claims that he powered the amplifier on the TDA7294 and he did not get anything warm, except bridges.Personally, I think that it was worth using non-polar electrolytes, but they seem to be up to 220uF.
I think you're right about "BAM !!!"
Only ripples will be greater: the rectifier is half-wave, therefore, to compensate for this capacity, it is necessary to significantly increase.
Quote: ino53
And about the polarities C3 and C4, how right?
That's right - in each arm, turn on the capacitors counter-sequentially and each bypass with a counter diode. That is, there will be not 2 capacitors, but 4 and 4 diodes.
Better to overeat than not to sleep !!! )))))
Author
Quote: R555
Kaput will come to them

The voltage should be much lower than the rated voltage of the capacitors, then they will survive ...
Yes, Valery You missed a very interesting. However. it is better for you xaxa

You are sure that you would have inserted your sharpest word, and to us, without that, a little ...

Read in the chat.
Author
Quote: Valery
missed something interesting?

Who sleeps a lot, he eats little :-)))
Why did I miss something interesting?))))))
Fuck it !! Here you go! ))) Always like that!)))
And about the polarities C3 and C4 I think so. Kaput will come to them the first time they are turned on. xaxa Bah! The change on the polar capacitor is tin. But, on the other hand, maybe, thanks to the bridge diodes, the polarities and voltages are always approximately equal on both outputs of these air conditioners.

Do you know the correct answer? If you know, tell me.
Yes, but it bothers me that in this circuit the change is supplied to the second bridge through 2 air conditioners of 470 microfarads, is this the same some drawdown going under load?
And about the polarities C3 and C4, how right?
......
Carefully, they are not very volts. And this is if more current is needed.

And further.
Quote: brnjh1
Quote: R555
Now I will turn on and configure

We want to see ... victory
Midpoint in a trance is optional.
Yes, by the way, but not 4 but 2 diodes, instead of a bridge, you can put 2 powerful diodes. Stop! Schottky. They seem to be in the same computer PSUs.
I like this option more, because the secondary winding of the transformer without a midpoint (tap) is easier to find.
Well guys, comments - this is not the place for you to sort things out - go to the PM or exchange contacts.

Srach cleaned, for the first time without warning, and upon repetition measures will be taken ...
Author
Quote: R555
Now I will turn on and configure

We want to see ... victory
Another option, but here the permissible current of the diodes should be twice as much, and the capacitance is cond. - at 4.
..
Of course smile
It's okay, it happens in the park.
ino53 , I'm sitting in soldering, and the beech is near, the site is open. What was thought. You said that there seems to be a common bridge in those factory BPs, but I doubted it. And now the Mayak-202 mafon circuit has surfaced in my head. There, after all, there is one bridge and one trance, and I know exactly two polar ones in Pitalovo UM.

Then it turns out, you can take one powerful trance, one good bridge and make channels on two bourgeois adjustable microcircuits on radiators?

Get a great PSU, no impulse noise. Well, the fact that the current through the channels will give out Amperes for 2 "total" is enough for a laboratory PSU. Quality BP.

What do you think about this? Will it turn out with one trance and one bridge? In my opinion, you can’t figure it out without a glass xaxa The campaign needs to draw a diagram ...
And about multichannel, from my own. (In order of boasting boast not_i
No, with one common rectifier this will not work, or rather it will work and will work. Until you want to get two polar explorers with a midpoint.

And connect the plus and minus channels to get the midpoint. Well then, well, you understand ...

As we at the institute liked to speak at lectures, one teacher, "Each spit has its own bypass." xaxa
Sorry, repeat
.....
No problem, with a ready trance (so as not to mess with rewinding) - well, two days of leisurely work.

We advise you to read:

Hand it for the smartphone ...