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Alteration of the power supply. Increase power

Greetings the inhabitants of our site!
Today, we, together with the author of the YouTube channel “AKA KASYAN”, will be engaged in increasing the power supply. As an experimental, we have a cheap charger for phones.

On it, the author will demonstrate the principle of rework, and you can use the same principle to rework other power supplies. The Chinese manufacturer claims that our power supply is five-volt and produces a current of up to 1A at the output, but now, let's check it.

As a meter, we have a high-precision usb tester. The load is a variable wire resistor or rheostat.


We turn on the tester to the charger and see that the voltage is really within 5V.
Well, it's time to load this miracle.


Here we clearly see that with an output current of more than 800 mA, the output voltage drops below 5V, and with a current of 850 mA the drawdown is very hard - this is the limit. If you ship more, protection will work. Based on this, we can say that the parameters declared by the manufacturer are overestimated, but even with a current of 800 mA such a unit will not last long. 400-500 mA output currents are more or less safe for him, this is enough for ordinary dialers, but not for smartphones.

As a result, using the data obtained, we can say that the power supply is within 4 watts. Remember this number and analyze the block.


Everything is budgetary inside, the quality of the board itself is not so hot. It was built according to a rather popular topology - a self-generating switching power supply with current protection and stabilization of the output voltage.

The block is built on only one transistor, as a rule, this is a high-voltage bipolar transistor.


There is another transistor in the circuit, a protection system is built on it, but more on that later.
Feedback or voltage stabilization is based on an optocoupler and an ordinary zener diode.


In general, if you look carefully, the board provides a seat for installing a voltage reference source, but the manufacturer decided to save money and installed a regular zener diode.

But if everything is done correctly, then such a simple circuit on a single transistor will work very well for many years. Now for the rework. First, we throw out the output rectifier (here there is a single-ampere Schottky diode 1n5819).

Next, we rummage through the reserves and find almost any Schottky diode with a current of 2-3A, in this case it is a 3 amp sb340.

It is quite large and is located next to the output electrolytic capacitor. Capacitors do not like heating, and the diode will just warm up, so it was installed on the back of the board, that is, on the side of the tracks.

From the plus line, just in case, the author strengthened the track with solder.

Next, we solder the input and output capacitors, both of them are electrolytic. The output costs 10V 470 microfarads, at the input of the high-voltage 400V 2.2 microfarads. The output capacitor should preferably be supplied with a low internal resistance. You can tear out such capacitors from computer power supplies.

The author found a capacitor at 1000 microfarads, in principle, enough for 470 microfarads. The second capacitor is replaced by the same, only 4.7 uF. Ideally, it is desirable to put the microfarad at 10, but there is not enough space in the case, so this is the solution.

Capacitors must be checked for serviceability: leakage, loss of nominal capacity and internal resistance. Then the fun begins. We evaporate the pulse transformer, remove the tape and throw the trance into boiling water for a minute, so that the glue weakens, and then carefully disconnect the halves of the core.

After that we remove the layer of adhesive tape and under it we find a thin winding - this is our basic winding, it is wound with a 0.15 mm wire and consists of 13 turns. By the way, the secondary winding of the transformer also contains 13 turns, this winding is carefully removed. After our alteration, it will need to be wound back, but the length of the wire is no longer enough, so the wire from it will no longer be useful to us. It is wound with a wire of 0.3 mm, hence such an insignificant output current.

Then we take a wire of 0.45 mm, put it in two and wind 13 turns onto the frame. There was a winding of 0.3 mm, and it became 2 by 0.45 mm, there is enough space on the frame.

All windings are wound in exactly the same order and direction as in the case of factory winding, so as not to confuse the beginning and end of the windings. That is, take a couple of pictures before the unwinding process, so as not to confuse anything. The insulation is heat-resistant tape. Next, we wind the base winding exactly as it was originally wound and again we put the insulation.

Everything is ready, it remains to assemble the transformer. Before assembly, carefully clean both the frame and the core halves from the old glue. We are assembling the transformer, the halves can be pulled together with tape or a drop of superglue, but this should be done only after we make sure that everything is working properly.


We put the transformer in place and, probably, you thought that was all? And no! We have yet to deceive the defense system. It’s a blessing to deceive defense in such a simple scheme. In general, we track the emitter circuit of our main transistor.

The emitter is connected to the input minus through a resistor. This is a low-resistance resistor with a resistance of several ohms, sometimes less, in this case, a resistor of 5.6 ohms.
We have this resistor as a current sensor and at the same time limits the current through the transistor. Protection works in a simple way: the more powerful the output load, the greater the voltage drop across this resistor, and at a certain moment this drop will be enough to trigger a low-power transistor. Opening it, it closes the base of the power transistor to ground and it closes, and, therefore, the output voltage disappears. Everything is very simple.

We change the resistor to a similar one, only with a resistance of 2.2 to 3.3 ohms.

Now everything, it remains only to repeat the test that we did at the beginning. The first start-up of the unit must be done through a 5-10 W safety lamp, this is mandatory, and in no case touch the board during operation, but it is better to close it with something dielectric.



As you can see, at a current of 1 - 1.3 A, we do not observe any noticeable drawdown. The output power of the power supply was almost 8 watts, but at the beginning it was only 4 watts. Result on the face.

This is of course cool, but the core of the transformer needs to be changed, it is now creeping out of one place to provide such power, in short, it works beyond its capabilities. Further, the author straightened out some crookedly soldered components and updated the soldering; in such budget blocks it is extremely unreliable. Well, in the end it will not be superfluous to clean everything from the flux and the power supply is, in principle, ready.



You can end here. Thank you for attention. See you soon!
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36 comments
Burner
I thought, since I had already disassembled the core, increase the gap in proportion to the current. To save induction. And then if the trance flies into saturation, the current in it grows too quickly. Extra dangerous heating of the transistor.
I soldered a 0.18 mm copper to the transistor flange. I have. On the MJE13005, by the way, I made 15 watts power supplies, they turned out to be quite good.
Quote: Guest Serge
2 A PSU is easy to buy for 2 raccoons.
This is where there is such a glorious place?
Guest serge
hands plus. but is it worth it to fix the gimor? 2 A PSU is easy to buy for 2 raccoons. :) only if there is a lot of free time, a big zashashnik of radio parts and an indefatigable desire to create ... and the core of the trance may not be able to withstand the increased load. will not bask in a childish way ...
Anonimus
The spread is not so great - according to this topology, almost all low-power (up to 100-200 watts) power sources are monitors, duty on duty in bp computer and so on. The difference is only in power. Well and of course the circuits are a little complicated for the stability of the results in mass production, and to increase energy efficiency.
Or do you still train on the charges from mobile phones?
In what you are right of course, but it is very difficult to master the repair of computer equipment, repairing wooden bills! smile
Anonimus
Quote: Korolev
I ask the help of specialists

But where do the specialists come from then? Without experience, I immediately repaired the welding inverter. Or did you still train on the charges from mobile phones? I believe that before you started kalym for money, there were a lot of training on something cheap.
a little confirmation of theory by practice
By the way, you can try to slightly increase the frequency of the generator, without rewinding the transformer, though you had to drill a lot of small holes in the case for cooling.
Then with what or what do you give up for repairs to specialists, or do you immediately buy a new one?
It depends on the situation, sometimes it’s really easier to buy a new one (time is money), sometimes I repair it myself, sometimes I ask the help of specialists. But in this particular article we are talking about a really cheap question! smile
Anonimus
Quote: Korolev
My time is more precious to me, especially when I huddle! smile

Then with what or what do you give up for repairs to specialists, or do you immediately buy a new one?
Anonimus
The question here is more about getting skills, a little confirmation of the theory by practice and a little bit of practical necessity.
Guest Sergey
Answer only one question. So I will give you such a PSU for exactly such an alteration. How much money will you take from me?
Lottery however
I completely agree with you, but when I choose, I look at dimensions and weight, the chances of winning increase! smile
Unfortunately, often, until you buy, you won’t know what the PSU parameters really are. Lottery, however. ((
The specimen being developed on the nameplate indicated overestimated data, perhaps the "rationalizers" were advised: iron allows you to make a BP that meets the declared characteristics. If there is time, why not finalize the unit, in fact earn two hundred in an hour, saved on buying a new PSU.
Guest Vladimir
In general, the game is not worth the candle. It’s easier to buy a more powerful power supply all the more. that they are like dirt.
Guest Igor
Uh ... Do you really recommend that everyone reassemble the transformer? Okay details, but trans ..
Guest Vitaliy
easier to buy a new one
This is an ordinary, civilian dog! And what does an army dog ​​do when there is nothing to do? That's right - paints the booth! This is a joke and not a hint. The author is good at something - what patience, but messing around with a not-so-interesting penny thing, the right word, there are many more interesting things.
I’ve been engaged in this for many years. The lamp fits any one up to 60 volts. You can use a variable resistor 30_40 watts. The circuit is proven, but the transistor fails during prolonged use. To avoid this, he needs an additional heat sink, ideally replace the transistor 1301 to 1305
Before sculpting a PSU to a column, read the instructions for it. And there it is written in Russian in white: “FORBIDDEN to make changes to the design” or something like that. Not enough gas explosions in your houses? Yes, even if the windows are plastic - the danger is even higher. You are not only risking ruining yourself, but also the whole staircase, people who are completely innocent of your disregard for security.
5 watts?
light bulb for a refrigerator or sewing machine
Quote: Guest Vlad
If in the gas column you need to file say 24 volts
Further, this theoretical opus is not worth reading. ((
Voldemar
When the dog does not do figs, she licks the eggs. Another question, what idiots have put so many likes, probably the author himself?
Guest Sergey
Everything is described correctly, except "we throw trance in boiling water for a minute"! Water can penetrate between the turns of the primary winding, and this is a breakdown and interturn short circuit. Typically, such transformers have a primary “winding” winding. It is better to heat with a regular hairdryer.
Guest Vlad
a problem with the connections, but you can take from the block not to bother with foreign parts and pulse circuits to assemble the usual straightened on a 220 to 12 transic and the whole thing is a stub circuit in any radio technology magazine and I was surprised to learn that there are no new generation domestic parts in nature
Guest Vlad
If you need to supply say 24 volts and a small current (to the electronics control board) in the gas column, this is, apart from say separate 220 volts, then I advise you not to bother with similar simple AC-DC converters, which are still not designed for round-the-clock operation, I advise proceed as follows - find in the house a LITTLE PULSE feeder for 9-12 volts (this kind of good was usually a lot before) with a current of up to 0.7-1 amperes, after the bridge, plug in a fresh high-quality (better LowESR) electrolytic capacitor and hang it on the floor from a feeder a ready-made step-up DC-DC converter to MT3608. What are the advantages: in this circuit you will have only one electrolyte, and even one operating at 50 Hz, in the event of a power surge MT3608 will simply be unloaded, and when the voltage drops, MT3608 still holds up to 2A, well, if suddenly MT3608 It’s going to happen, the worst thing that will happen is that the control board will receive not 24V DC, but 9-12 volts.
All this is applicable naturally if the currents consumed by your geyser and the final electrical power (at low voltage) will correspond to the devices used - i.e. a feeder of the appropriate power and the rated current at the DC-DC output is not higher than 1A (2A for MT3608 in a jump). This circuit is working, I have a double-circuit gas boiler working in which I am tired of changing the FSD210 in an AC-DC converter.
I would highly advise against climbing into gas equipment with my own modifications. Batteries stand there - let them stand.
the question of the penny of what he can do doesn’t say ... He just does ...
No need so categorically all under one comb! Yes, I won’t bother with cheap penny, I’ll go and buy it! My time is more precious to me, especially when I huddle! smile
It’s easier in a 5-volt PSU (from a router for example) to install a linear stabilizer and it will be fine. About 5 years ago, I did similar, it still works.
Max
A person who "does everything himself for 100" doesn’t say a penny about what he can do himself ... He just does ...
Guest Vladimir
Something I did not meet so simple with an optocoupler! I'm more interested in the ability to adjust the power supply for use in a gas column. Now it’s not a problem to find or buy a more powerful power supply, say from an e-book.
I, unlike you, can do everything for 100, for me there is absolutely no difference what to do or what to repair, I always thought that a talented person is talented in everything, go to my YouTube channel and I’m not hiding just a visitor .
Guest Leonid
It seems to me that such a block is easier to assemble from scratch yourself than to remake Chinese junk.
Guest Vlad
Hemorrhoids for someone who does not know how to do anything, for example, I really liked the alteration, I’ll definitely do it.
Such a "hemorrhoids" because of a penny thing.
The first start-up of the unit must be done through a 5-10 W safety lamp,
The lamp is rare, not easy to find. ;)

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