Several times I was rescued by power supplies, the circuits of which have already become classic, remaining simple for anyone who has soldered something electronic at least once in their life.

Similar circuits were developed by many radio amateurs for different purposes, but each designer put something of his own into the circuit, changed calculations, individual components of the circuit, conversion frequency, power, adjusting it to some needs known only to the author himself...

I often had to use such circuits instead of their bulky transformer counterparts, reducing the weight and volume of my structures, which needed to be powered from the network. As an example: a stereo amplifier on a microcircuit, assembled in an aluminum case from an old modem.

There is no particular point in giving a description of the operation of the circuit, since it is classical. I will only note that I refused to use a transistor operating in avalanche breakdown mode as a triggering circuit, because unijunction transistors type KT117 work much more reliably in the launch unit. I also like running on a dinistor.

The figure shows: a) pinout of old KT117 transistors (without a tongue), b) modern pinout of KT117, c) arrangement of pins on the circuit, d) analogue of a unijunction transistor on two ordinary ones (any transistors of the correct structure will do - p-n-p structures (VT1) of type KT208, KT209, KT213 , KT361, KT501, KT502, KT3107; n-p-n structures (VT2) type KT315, KT340, KT342, KT503, KT3102)

UPS circuit based on bipolar transistors

UPS circuit based on field-effect transistors

The circuit on field-effect transistors is somewhat more complicated, which is caused by the need to protect their gates from overvoltage.

Error. Turn diode VD1 in reverse!

All winding data of transformers are shown in the figures. The maximum load power that can be supplied by a power supply with a transformer made on a 3000NM 32×16X8 ferrite ring is about 70W, and on a K40×25X11 of the same brand is 150W.

Diode VD1 in both circuits, it disables the trigger circuit by applying a negative voltage to the emitter of the unijunction transistor after the converter has started.

Of the features- power supplies are turned off by closing winding II of the commutating transformer. In this case, the lower transistor in the circuit is turned off and generation is interrupted. But, by the way, generation failure occurs precisely because of the “short-circuiting” of the winding.

The blocking of the transistor in this case, although it clearly occurs due to the closure of the emitter junction switch by the contact, is secondary. In this case, a unijunction transistor will not be able to start the converter, which can be in this state (both switches are locked at direct current through the practically zero resistance of the transformer windings) for any length of time.

A correctly calculated and carefully assembled power supply design, as a rule, is easy to start under the required load and behaves stably in operation.

Konstantin (riswel)

Russia, Kaliningrad

Since childhood - music and electrical/radio equipment. I re-soldered a lot of different circuits for different reasons and just for fun, both my own and others’.

Over 18 years of work at North-West Telecom, he has made many different stands for testing various equipment being repaired.
He designed several digital pulse duration meters, different in functionality and elemental base.

More than 30 improvement proposals for the modernization of units of various specialized equipment, incl. - power supply. For a long time now I have been increasingly involved in power automation and electronics.

Why am I here? Yes, because everyone here is the same as me. There is a lot of interest here for me, since I am not strong in audio technology, but I would like to have more experience in this area.

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Many people who are starting to get acquainted with impulse generators begin to collect what is simpler.
Including this diagram:

I also started with her.

It’s a completely working circuit, but if you expand it a little, you’ll get a decent switching power supply for beginners and more.
Something like that:

Most of the parts were soldered from old computer power supplies and old monitors. In general, I collected it from what normal people throw into a landfill.
This is what the assembled SMPS looks like:

And here is the power supply with a load. 4 lamps of 24 volts. Two pieces in each shoulder.

I measured the total voltage and current in one arm. After half an hour of operation with a load, the radiator heated up to about 50*.
In general, the result was a 400-watt power supply unit. It is quite possible to power 2 amplifier channels of 200 Watt each.

The main problem for beginners is winding the transformer.
The transformer can be wound on rings, or the trans can be pulled out of the computer power supply.
I took a trans from an old monitor, and since monitors have a trans with a gap, I took two at once.

I throw these trances into a jar, fill it with acetone, close the lid and smoke.

The next day I opened the jar, one trance fell apart on its own, the second one had to be moved a little with my hands.

Since two trances will make one, I unwound one reel. I don’t throw anything away, everything will be useful for winding a new trance.
You can, of course, cut off the ferrite to remove the gap. But my old monitors are like dirt and I don’t bother with grinding off the gap.
I immediately rearranged the legs, the pinout was the same as in the computer trance, and threw away the extra ones.

Then in the Old Man program I calculate the voltage and current I need.
I adjust the calculations to the wire that is available.
Coil length 26.5mm. I have 0.69 wire. I consider 0.69 x 2 (double wire) x 38 turns / divided by 2 (layers) = 26.22 mm.
It turns out that 2 wires of 0.69 will lie in exactly two layers.

Now I’m preparing copper tape for winding the secondary. It is easy to wind the tape, the wires do not get tangled, do not fall apart and lie turn to turn.
I wind it with four 0.8mm wires at once, 4 semi-windings.
I hammered 2 nails into the rail, pulled 4 wires, coated it with glue.

While the tape is drying, I wind the primary. I tried to wind two identical trances, in one I wound the entire primary, in the other I wound half of the primary, then the secondary and at the end the second half of the primary (since computer trances are wound). So I didn’t notice any difference in the work of both trances. I don’t bother anymore and wind the primary intact.
In general, I wind it: I wound one layer of primary, since I don’t have a third hand to support it, I wrap it with narrow tape in one layer. When the trans heats up, the tape will melt, and if a turn has been loosened somewhere, the tape will stick together like glue. Now I’m winding the film tape, the one from the disassembled trance. and finish the primary.

I insulated the primary, put a screen (copper foil) just so that there was no full turn, it should not converge by 3-5mm.
I forgot to take a picture of the screen.
The tape has dried, and this is how I wrap the secondary one.

I wound a layer of recycled material, aligned the row with narrow strips from the disassembled trance, insulated it, wound the secondary material, insulated it

I stuck the ferrites in, pulled them off with narrow tape (about 10 layers), filled them with varnish from a can on top and bottom so that the trans would not cycle and the fan would be warm. Let it dry.
As a result, the finished transformer:

It took about 30 minutes to wind the trance. And about an hour to prepare and strip it and tin the wires. ARCHIVE:Download Chapter.

In amateur radio practice, many homemade designs remain unattended on shelves for the reason that they do not have a power supply. One of the most repeatable designs is the low frequency power amplifier, which also needs a power source. Network transformers for powering powerful amplifiers cost a lot of money, and their size and weight are sometimes inappropriate. For this reason, switching power supplies have recently found widespread use. These units are fully electronic and operate in pulse mode. Due to the increased operating frequency, it is possible to dramatically reduce the size and weight of the power supply. The circuit diagram for such a power supply was found on one of the foreign sites; without thinking twice, I decided to repeat the design.

The design is particularly simple and cheap; in my case, I spent only $5 on transistors and a microcircuit; everything else can be found in a non-working computer power supply.
The power of such a unit can reach up to 400 watts; for this you only need to change the diode rectifier and electrolytes, instead of 220 uF, set it to 470.

You can take a ready-made rectifier from a computer power supply or assemble a bridge from diodes with a current of 3 A or more, the reverse voltage of the diodes is at least 400 Volts.

The first start-up of the circuit must be carried out with a 220 Volt 100 - 150 watt incandescent lamp connected in series, so that the circuit does not explode if installed incorrectly.

The type of power supply, as already noted, is switching. This solution dramatically reduces the weight and size of the structure, but works no worse than the ordinary network transformer we are used to. The circuit is assembled on a powerful IR2153 driver. If the microcircuit is in a DIP package, then a diode must be installed. As for the diode, please note that it is not an ordinary one, but an ultra-fast one, since the operating frequency of the generator is tens of kilohertz and ordinary rectifier diodes will not work here.

In my case, the entire circuit was assembled in bulk, since I assembled it only to test its functionality. I barely had to adjust the circuit and it immediately started working like a Swiss watch.

Transformer— it is advisable to take a ready-made one, from a computer power supply (literally any one will do, I took a transformer with a pigtail from an ATX 350 watt power supply). At the output of the transformer, you can use a rectifier made of SCHOTTTKY diodes (can also be found in computer power supplies), or any fast and ultra-fast diodes with a current of 10 Amps or more, you can also use our KD213A.

Connect the circuit to the network through a 220 Volt 100 watt incandescent lamp; in my case, all the tests were done with a 12-220 inverter with short-circuit and overload protection, and only after fine tuning I decided to connect it to the 220 Volt network.

How should the assembled circuit work?

• The keys are cold, without an output load (even with an output load of 50 watts, my keys remained icy).
• The microcircuit should not overheat during operation.
• Each capacitor should have a voltage of about 150 Volts, although the nominal value of this voltage may deviate by 10-15 Volts.
• The circuit should operate silently.
• The microcircuit's power resistor (47k) should overheat slightly during operation; a slight overheating of the snubber resistor (100 Ohm) is also possible.

The main problems that arise after assembly

Problem 1. We assembled a circuit; when connected, the control light that is connected to the output of the transformer blinks, and the circuit itself makes strange sounds.

Solution. Most likely there is not enough voltage to power the microcircuit, try reducing the resistance of the 47k resistor to 45, if that doesn’t help, then to 40 and so on (in 2-3kOhm steps) until the circuit works normally.

Problem 2. We assembled a circuit; when power is applied, nothing heats up or explodes, but the voltage and current at the transformer output are negligible (almost zero)

Solution. Replace the 400V 1uF capacitor with a 2mH inductor.

Problem 3. One of the electrolytes gets very hot.

Solution. Most likely it is not working, replace it with a new one and at the same time check the diode rectifier, maybe it is because of the non-working rectifier that the capacitor receives a change.

The switching power supply on the ir2153 can be used to power powerful, high-quality amplifiers, or used as a charger for powerful lead batteries, or as a power supply - all at your discretion.

The power of the unit can reach up to 400 watts, for this you will need to use a 450-watt ATX transformer and replace the electrolytic capacitors with 470 µF - and that’s it!

In general, you can assemble a switching power supply with your own hands for only $10-12, and that’s if you take all the components from a radio store, but every radio amateur has more than half of the radio components used in the circuit.

Good afternoon My opinion: The scheme (first) will work, all you need is there! Tips to replace the driver, add capacity, etc. there are unfounded ones. If you change something, then this is a separate scheme and other discussions. The weak point is capacitors with a midpoint of 200 V! Yes, it will work, but if the capacitor could, he expressed his wishes to increase the breakdown voltage to 350 V! Just a filter is half the trouble, but decoupling the load and working on the transformer winding is another matter. We count, if you are not too lazy: 310 V (for example, power supply) + 150 V (EMF of the transformer inductance discharge) = 460 V. Half is equal to 230 V. Or maybe “BANG!” - maybe, but it will be “p-sh-sh-sh-i-k!” and the capacitor will leak. Seems to be explained clearly. And the scheme will work and will give what it was calculated for! Fact! Protection! The best defense is the one that is simple! Those. fuse at both input and output. The fuse response speed is sufficient for a key pulse current of 25 A! Do you understand that this is enough? Enough. To obtain maximum efficiency, you need to select the pulse frequency for the transformer used, this is obvious because The ferrite was heated to 100 degrees. lost properties, the calculation will be adjusted. How to choose is simple. We measure the current consumption of the circuit after the rectifier. By changing the frequency from higher to lower we find the moment the current increases - stop! We increase the frequency by 1-2 kHz. All! How to change the frequency? Simply, replace the resistor Rt with a trimmer of higher resistance (without fanaticism). You also need to select the frequency for the transformer from the computer's power supply. The range of operating frequencies is from 32 KHz to 55 KHz. Good luck to everyone. As for the second scheme, this is a variant of all the errors of the first and some other schemes from the Internet! Why? The first and most important thing in the “datasheet” IR2153 IRF740 is a clear contradiction: the breakdown voltage is not less than 600 V. and the keys are 400 V. The gate capacitance for 2153 (load) is no more than 1000 pF, and for 740 = 1400 pF. Yes, the light bulbs will glow, but with this unit you are doomed to buy more than one set of parts. The output voltage will sags - there is no required pulse steepness. If the efficiency is below the maximum, we warm the environment. In general, the selection of parts for the (second) scheme is a mistake! For 740 you need a driver 2155 (manufacturer's recommendations) with a capacity of up to 2200 pF in load. Scheme - experiment with explosion! Assemble strictly with glasses and gloves! What would I pair? Keys STP5NK60C (or 4NK60, 6NK60, 7NK60...) When choosing a key, look at the current at 100 g - 2-3 A is enough, and of course the gate capacity =< 1000 пф. Остальное все рабочее, правда я бы подобрал частоту и ток драйвера как описал выше. Напомню: запас в электронике не всегда уместен. Скажем взять ключи на пробой в 1000 в - это неправильно. IRF740 - отличные ключи для применения в Китае, напряжение сети 110 - 120 в. Как то так.