High voltage and more. High voltage and more DIY voltage converter 220 12 volts
Materials from blogger Aka Kasyan's channel were used. The circuit and assembly of a simple step-up voltage inverter from 12 to 220 Volts, with available components, is shown in detail. Powerful good circuits are difficult even for advanced radio amateurs, and unattainable for beginners. Therefore, a variant of the design of an inverter from parts of a non-working computer power supply was considered. The scheme was chosen to be simple so that everyone could repeat it. They do not require configuration, there are no options based on a PWM controller, which would complicate the task and make configuration difficult.
It is best to buy radio-electronic spare parts from this Chinese store.
A video tutorial is at the bottom of the post.
The circuit is presented for informational purposes only; it does not have stabilization, so the output voltage will deviate from the declared 220 volts. It also does not have any protection and the output is direct current. This means that AC motors and mains transformers cannot be connected to this output. You can connect a soldering iron, small incandescent lamps, and economy lamps, but it is still not highly recommended to use such a circuit for domestic purposes.
As a donor, a non-working computer power supply.
The 220 volt boost converter circuit is below.
From the block you will need: a power pulse transformer, a capacitor, a group stabilization choke, and a few more components, which are discussed below. To remove these components, you need to separate the board from the case. This is easy to do. To unsolder the transformer, we use a soldering iron and a desoldering pump. It is necessary to unsolder the radiator on which the main power transistors are located; insulating gaskets and washers are needed for them.
In addition to the elements removed from the computer power supply, you need an additional two resistors with a power of 2 watts or 1 watt, with a resistance from 270 to 470 ohms. You also need two UV 5408 diodes, you can use any ultrafast, with a current of at least 1 ampere, a voltage of 400 volts or higher, 2 zener diodes with a stabilization voltage from 5.1 to 6.8 volts, preferably 1.2 watts. N-channel field effect transistors Rf840 or more powerful Rf460 or 250 from the Rfp line. This circuit will contain 18 ampere 600 volt transistors, type 18N60.
The next element is the throttle. There are several independent windings on the group stabilization choke; they can be wound or the wires can be cut off, leaving one power winding. If the choke is wound from scratch, then the winding consists of a wire of 1.2-1.5 millimeters and contains from 7 to 15 turns.
Transformer. There is a secondary output winding, 2 contacts for them and a primary one. Note the tap and the two right contacts. You need two contacts on the left (the video was mirrored). We put a mark next to them; the power terminals of the transistors are connected to these contacts. Next, we connect our 1 microfarad capacitor in parallel to the same contact from the transformer.
Circuit installation
Transistors are installed on the heat sink. In the video, everything is assembled using a hinged installation for simplicity. We must bend the middle terminals of the transistors and connect them to the two right terminals of the transformer.
The mounted circuit diagram looks like this.
Now you need to connect a low-power incandescent lamp to the output winding and apply power to check the circuit’s functionality. You need to unsolder two electrolytic capacitors from the computer power supply. Based on these capacitors and diodes, we will create a symmetrical voltage multiplier, or.
Since the output voltage from the secondary winding of the transformer is approximately 100 volts, it needs to be raised. For this purpose, the multiplier increases the voltage by 2 times.
In addition to capacitors, two fast-acting diodes are needed. In this version, UF 5408, but you can use any diodes for 400-600 rings with a current above 2-3 amperes.
A small incandescent lamp with a power of about 60 watts burns at full heat, the batteries are low-power, but this does not interfere with the work process.
In conclusion, we can say that this simple inverter circuit operates over a wide range of supply voltages up to 12 volts. It starts working at 6 volts, giving an output of 220 volts. Simplicity and accessibility are the main advantages of the scheme. It is better to supply power through a 15-20 ampere fuse. It must be taken into account that a high voltage remains on the multiplier capacitors. Therefore, after disconnecting the device be sure to discharge the multiplier 40 watt incandescent light bulb.
Resistors are also drawn in the circuit; the capacitor is shunted by these resistors. These resistors are not installed in this project, but it is definitely recommended to use them.
Transistors can be used at voltages that are not as high as indicated above. You can limit yourself to a much lower voltage, for example 40-55 V, for example irfz44n is suitable, the main condition is that they hold current and have the minimum possible channel resistance, this determines the heating of the circuit and drawdown under load. In other words, the lower the resistance of the field-effect transistor channel, the more O More power can be obtained with less heating of the transistors.
Comments (41):
#1 Snow White February 19 2015
Perfetto. Excellent This circuit seems to be what I was looking for about the transistor, very interesting. If you increase the number of turns, say three times, the current on KT 817 will also drop to 0.6. It doesn't work fast enough, is this the reason for the high current?
To be honest, I haven’t tried to increase the turns. As for the performance speed, yes, that’s why it was replaced with KT940. the current can be reduced further. From the lamp, take only the lamp itself and throw the board out of it. then the current is in the range of 0.3-0.35A..
#3 Selyuk May 12 2015
Everything is very “simple”, but where can I get the transformer cups??
#4 root May 12 2015
In the transformer design of this high-voltage converter there is no gap between the ferrite cups, so you can try using a ferrite ring or frame from a pulse transformer with a ferrite core (you can take it from a non-working computer power supply).
You will need to experiment with the number of turns and output voltage.
#5 pavel June 01 2015
What is the principle for calculating a transformer and selecting transistors for this inverter? I would like to make one with a power supply of 60 volts.
The cups were taken because they were just there, and the number of turns in such a core is needed less. I haven’t tried ferrite rings; it works fine on regular W-shaped ferrite. I don’t remember how many turns I wound, the primary one seemed to be 12 turns with 0.5mm wire, and the booster one was done by eye until the frame on the core was filled. The transformer was taken from a 4 by 5 cm monitor.
#7 Egor October 05 2015
I have a question for you: how many ohms is the resistor on the left at 220???
I'm just not very good at electronics)))
#8 root October 05 2015
If there are only numbers next to the resistor, that means the resistance is in Ohms. In the diagram, the resistor has a resistance of 220 ohms.
Tell me, is it possible to use your circuit to power the MTX-90 thyratron and not from 12, but from a 3.7 volt battery?
If possible, what are the best transistors to use? The MTX-90 has a small operating current - from 2 to 7 mA, and the voltage for ignition needs about 170 volts, well, you can experiment with this with a transformer (about voltage).
I don’t even know what to answer. Somehow I didn’t think about it.. Why do you need to power the thyratron from this circuit? In principle, it will work, of course, the only question is how... from 3.7 volts it is also possible, but the windings must be recalculated or selected experimentally.
#11 Oleg December 13 2015
People, tell us how to make an inverter from transistors from a Chinese typewriter on a control panel. Is it possible to install a ring ferrite core and is it possible to make a 3-fold difference in turns? I should make an inverter this way just for fun and to make it easier. And is it possible to set the input voltage to somewhere around 3V?
Please answer! I will be glad if you answer all my questions! I'm waiting for your answers!
#12 Alexander December 17 2015
I have 30/10 ferrite cups, is it possible to wind a trans on them and what number of turns should be wound, at least approximately.
#13 Alexander January 24 2016
Everything works great there, both the 15 watt lamp and the 20 watt one. More powerful transistors are simply needed. KT940 can be left alone, but 814 could at least be replaced with KT837. And if the current is high, you don’t need to rewind anything, you just need to increase the value of the resistor to 3.1k. And the transformer is not necessarily of this size, even a pulse generator will work from charging, transistors will still play a special role. p.s. These transistors have a power of no more than 10 watts
#14 Eduard February 01 2016
What kind of transistor can I replace KT814 with? Can I use 13005 or KT805?
#15 Alexander February 03 2016
Change it to KT805 - you'll scrape off a lot of power, because according to the datasheet, KT805 can give up to 60 watts
KT814 is p-n-p conductivity, and KT805 and 13005 are n-p-n..., of course you can’t Eduard...
#17 Mars May 11 2016
Instead of KT814 I installed KT816.15W lamp pulled.
#18 sasha November 06 2016
I installed KT805 and KT837. primary 16v.0.5mm. secondary 230v. 0.3mm. lamp 23W. glows great.
#19 Eduard November 19 2016
March. counter question, what then can replace the KT940, so that the KT814 can be replaced with KT805 or 13005 and change the power polarity? An idea arose: I removed the 12-volt pulse transformer from the electronic transformer for halogen lamps, there is just a secondary of 12-14 turns and The primary is about 150-200 turns. If you deploy it as a booster and plug it into this circuit? I think it should work, but if you replace the combination of KT814 and KT940 with something more modern, then you can squeeze out up to 40 W of power? I also want to try it on the UC3845 PWM controller , the circuit there is generally primitive: a UC3845 microcircuit, in its circuit a frequency-setting resistor and a film capacitor, an IRFZ44 field-effect transistor and a transformer from an electronic transformer included in the circuit as a step-up, as a result we have up to 100 W of power at 12 volts
and why "..940 volts in the old colors in abundance.. everyone has nowhere to put it... replace it with any reverse transistor, but you want 805, then yes..940 on forward conduction.... and change the polarity... but again -why do everyone have so many of these in their bins...
#21 pavel February 09 2017
why do you need to increase the power of the circuit :)? What, will you use KrAZ batteries (190 a/h)?? this circuit makes sense, as a friend correctly said, if you use a bulb from a lamp with a burnt-out circuit. Otherwise, to hell with the button accordion: an LED lamp from the same battery, with the same light output, will illuminate many times longer!..
#22 pavel February 09 2017
Now about the transistors: you can change them, but you need to remember that any power transistor provides its declared power only when using an appropriate heat sink. this fact directly affects the dimensions of the entire device. and where will you get energy saving? l ampu more powerful than 30 watts = 150? I haven't seen it on sale. and I already talked about the battery for such a “pacifier” :). so, know your limits, inventors, good luck!
#23 Eduard February 24 2017
March, I just have a problem with the Soviet KT940 and KT814. Basically in my reserves I have imported powerful high-frequency bipolar transistors 13005 for 5 amperes 400 volts, and the like. They managed to light the flask at full brightness from a 30 W energy-saving device, while the transistor was slightly warm. And the Soviet KT814 and KT805 ARE GLUGGY BY THEMSELVES BOIL QUICKLY EVEN WITH A RADIATOR
I would not say that the KT805 is buggy... depending on which one you use. in plastic they are unreliable, there is such a thing, and then for some 80 years. take 805 in metal, it’s generally an indestructible transistor. However, it is necessary to emphasize the fact that they are buggy not because they are bad, but because they did not fall into entirely capable hands, just
But you can even install imported microwave transistors, it will work!!! verified!!. In this article, I wasn’t trying to create a miniature lamp, but rather how to fix a burnt-out lamp at minimal cost. to serve again
the 814 collector should be grounded through a 10 µF capacitor, otherwise when switching the surge is very large.
The 814 transistor is in a half-open state - however, it needs a radiator.
It was easier to use a blocking generator.
what other 10 microfarad capacitor, what nonsense, is it really not clear from the photo that the miniature radiator will all fit into a pack of cigarettes. and using a blocking generator is no easier. there you need at least three windings. and the transistor will heat up there no less!!!
#28 IamJiva August 14 2017
blocking generator serves the same purpose, to provide feedback (bring the microphone to the speaker so that it buzzes), if you did without a microphone, why don’t you need it, here you got by adding a transistor, in blocking you can get by with one transistor, and turn the phase around with turns of the winding, which (allow ) can be independently connected in any polarity. You can squeeze out a lot of watts, but it’s difficult, part of the energy (for powerful lamps is significant, up to 90%) is lost on the diode bridge and electrolyte (in the lamp rectifier) that are cheap (especially if powerful) and 50Hz are suitable, at 50kHz smoke can already come from them and the voltage never appears to start the lamp, 50Hz diodes (simple, that is, not ultrafast or Schottky) do not have time to lock, and drain the charge back into the winding or somewhere else, this causes heating of everything and incorrect operation of the generator, the electrolyte has inductance (series) , and a short pulse it only “recognizes” but is in no hurry to carry out the order, while waiting for the command to set it aside... the current begins to increase to infinity or as long as they give, for 50Hz instantly, for 50kHz - never... the transistor needs to be fast, it can get warm and NO way, IRF840 2 pcs correctly used provided on 4 4 ohm columns of 500wt each, 2000 Wt power in class D powered by +-85V (170V) TL494 PWM, Ir2112 driver in the gates, 4 pcs ultrafast diodes shunt the SI and IC, varistors 400V BC 30V SI
2kW drum and bass power, they were a little warm on the same radiators as here, at the output there is a choke from the fuel assembly and 200 turns, at 2500wt they burned out without warning
It would be a good idea to bypass the output transformer of the primary with a diode, or better yet with a varistor (from flyback impulses possible in the event of a load disconnection, the selection of transistors and turns of the primary for maximum efficiency is as important and valuable as the ratio of sugar and vinegar with water + time on the timer in the microwave, so go away and take out the lollipops, the circuit works like a juggler you’ve never seen, they hope for the ease of transferring the ideal-harmony-efficiency-power to another circus and there’s no need for a jacket
One question for the author. This converter will pull an electric razor from Kharkov, Agidel, Berdsk, etc.
I need just such a miniature one that I can always build it into my shaving machine.
Just don’t write that there are plenty of battery-powered and wind-up electric shavers on sale. My dear to me.
She's been with me half my life.
Good luck.
#30 root January 21 2018
To power a 220V electric razor from the car's on-board network, it is better to assemble some more reliable and powerful voltage converter. Here are a few similar schemes:
- Voltage inverter 12V to 220V from available parts (555, K561IE8, MJ3001)
- Simple voltage inverter 13V-220V for car (CD4093, IRF530)
Thanks for the links, but it’s too expensive and difficult to assemble on your knees.
I don't have such details. But the old color.tel. and there is a tape recorder. It's all there
People write that you can increase the power by replacing transistors with 805.837.
An electric razor consumes 30 watts. Maybe it will. What do you think?
I came across the Variom A ROM.
The trouble is that the P216G transistors can no longer be found, and one of them is not working. According to the parameters, the GT701A seems to be suitable, but here’s how to determine the resistors. There are only 4 of them, two pairs. I don’t think it will work just replacing both P216Gs with GT701A. Tell.
#33 root February 05 2018
Agu1954, P216 transistors can be replaced with GT701A or P210V. Below are the main operating limits of these transistors:
- P216G: Ukb, max=50V; Ik max=7.5A; Pk max=24W; h21e>5; f gr.>0.2 MHz;
- P210V: Ukb, max=45V; Ik max=12A; Pk max=45W; h21e>10; f gr.>0.1 MHz;
- GT701A: Ukb, max=55V; Ik max=12A; Pk max=50W; h21e>10; f gp.=0.05 MHz;
Replace two transistors P216 with GT701A (P210V). For safety reasons, the first connection of the circuit to the battery is made through a 3A fuse.
P.S. Please ask questions not related to the diagram given in the publication on the forum or in our social groups VK and FB.
#34 Sergey February 16 2018
#35 root February 16, 2018
Hello, Sergey. An old, and no longer working, postal address was indicated. Fixed it with a new one.
#36 Sergey February 16 2018
This converter operates at a frequency far greater than 50Hz. somewhere in the region of 20-50 kHz. Even if you increase the power by replacing transistors with more powerful ones, the razor will still not work. the engine simply cannot physically operate at a frequency of tens of kilohertz
#38 Petro Kopitonenko November 19 2018
To lower the frequency of the current on the converter, you must try to increase the number of turns of the transformer, both the primary and secondary windings. Where am I coming from? 50 hertz transformers have a large number of turns. And high-frequency ones have a small number of turns. This is the same as in oscillatory circuits, the frequency depends on the number of turns. I soldered an experimental converter with a factory transformer at 50 hertz. There, two primary windings are wound with 40 turns instead of 10 turns according to the circuit. I could hear the transformer humming at a frequency of about 40 hertz by ear. If it was a frequency of 50 kilohertz, I would not hear anything!!!
#39 David June 13 2019
Or you can use a ready-made transformer in this circuit. For example, step-up transformer TP 30-2, just connect in reverse (to the 15 volt output winding)
#40 root June 15 2019
The circuit requires a high-frequency transformer; TP 30-2 or another network transformer with Sh-like or toroidal iron will not work here.
#41 Dmitry October 06 2019
Good day! The primary of the transformer must be equipped with a snubber. With the second transistor you are practically switching the inductance. And don’t care that the voltage is low! With a snubber chain it will be easier for transistors. Someone above already suggested shunting the 814 collector with a capacitance, but it went unheard. But better, of course, is a classic snubber - diode, resistor, capacitor.
In this article you can find detailed step-by-step instructions for making a 220 V 50 Hz AC inverter from a 12 V car battery. Such a device is capable of delivering power from 150 to 300 W.
The circuit diagram of this device is quite simple..
This circuit operates on the principle of Push-Pull converters. The heart of the device will be the CD-4047 board, which works as a master oscillator and also controls field-effect transistors that operate in switch mode. Just one transistor can be open; if two transistors are open at the same time, a short circuit will occur, as a result of which the transistors will burn out; this can also happen in case of improper control.
The CD-4047 board is not designed for high-precision control of field-effect transistors, but it copes with this task perfectly. Also, for the device to operate, you will need a transformer from an old 250 or 300 W UPS with a primary winding and a middle positive connection point from the power source.
The transformer has a fairly large number of secondary windings; you will need to use a volt-ohmmeter to measure all the taps and find a 220V network winding. The wires we need will give the highest electrical resistance of approximately 17 ohms, you can remove the extra leads.
Before you start soldering, it is advisable to double-check everything again. It is recommended to select transistors from the same batch and the same characteristics; the capacitor of the driving circuit often has a small leakage and a narrow tolerance. Such characteristics are determined by a transistor tester.
Since the CD-4047 board has no analogues, you need to purchase it, but if necessary, you can replace the field-effect transistors with n-channel ones with a voltage of 60V or more and a current of at least 35A. Suitable from the IRFZ series.
The circuit can also operate using bipolar transistors at the output, but it should be noted that the power of the device will be much less when compared with a circuit that uses “field switches”.
Limiting gate resistors should have a resistance of 10-100 ohms, but it is preferable to use 22-47 ohm resistors with a power of 250 mW.
Often the master circuit is assembled exclusively from the elements indicated in the diagram, which has precise settings at 50 Hz.
If you assemble the device correctly, it will work from the first seconds, but when starting it for the first time, it is important to be on the safe side. To do this, instead of a fuse (see diagram), you need to install a resistor with a nominal value of 5-10 Ohms or a 12V light bulb, in order to avoid the transistors exploding if mistakes were made.
If the device operates stably, the transformer will make sound, but the keys will not heat up. If everything works correctly, the resistor (bulb) needs to be removed, and power is supplied through the fuse.
On average, the inverter consumes energy when the robot is idling from 150 to 300 mA, depending on the power source and the type of transformer.
Then you need to measure the output voltage, the output should be about 210-260V, this is considered a normal indicator, since the inverter does not have stabilization. Next, you need to check the device by connecting a 60-watt light bulb under load and letting it run for 10-15 seconds; during this time the keys will heat up a little, since they do not have heat sinks. The keys should heat up evenly; if the heating is not uniform, you need to look for where errors were made.
We equip the inverter with the Remote Control function
The main positive wire should be connected to the middle point of the transformer, but for the device to start working, a low-current positive must be connected to the board. This will start the pulse generator.
A couple of suggestions about installation. Everything is installed in the computer power supply case; the transistors should be installed on separate radiators.
If a common heat sink is installed, be sure to isolate the transistor housing from the heatsink. The cooler is connected to a 12V bus.
One of the significant disadvantages of this inverter is the lack of short circuit protection and if it occurs, all transistors will burn out. In order to prevent this, you must install a 1A fuse at the output.
To start the inverter, a low-power button is used, through which plus will be supplied to the board. The power busbars of the transformer should be fixed directly to the radiators of the transistors.
If you connect an energy meter to the output of the converter, you will be able to see that the outgoing frequency and voltage are within the permissible limits. If you get a value greater or less than 50Hz, you need to adjust it using a multi-turn variable resistor, it is installed on the board.
When it is necessary to create mains voltage in a car, special 12-220 converters are usually used. There are inexpensive standard inverters on sale for about 20-30 dollars. However, the maximum power of such devices is, at best, about 300 watts. In some cases, this power may not be enough.
You can get power for a powerful amplifier through small transformations. It is enough just to replace the secondary winding on a standard inverter. After this, you can get any value of the input voltage. For example, the power of a 400 Watt inverter will increase to 600 Watts.
To increase power at home, experts recommend using a simple method. It will be necessary to replace the high-power bipolar switches with IRF 3205.
An inverter is used for operation, to which it is possible to connect 4 pairs of output transistors. Therefore, the device, after carrying out the necessary work, will be able to produce a power of about 1300 watts. If you buy a ready-made inverter with such parameters, its cost will increase to 100-130 dollars.
It is worth noting that the traditional push-pull circuit of the device does not contain protection against overheating, short circuit and output overloads.
The generator is based on a TL 494 microchip, which has an additional driver. It is necessary to replace low-power bipolar transistors with domestic analogues (KT 3107).
In order not to use powerful switches to supply power, the inverter is equipped with a remote control circuit.
In the driving part of the device, special SCHOTTTKI diodes type 4148 are used (domestic KD 522 is also suitable). The transistor in the remote control circuit is replaced with KT 3102.
After this, you can move on to the most important part of the project - the transformer. This element is wound on a pair of glued 3000 NM rings. Moreover, the size of each of them is 45x28x8. For a tighter fixation, the rings can be wrapped with tape.
Then the rings are wrapped on top with fiberglass (the cost in the store is no more than $1). It is quite acceptable to replace this material with fabric electrical tape.
Fiberglass is cut into small strips about 2 cm wide and no more than 50 cm long. The material for work has high heat resistance, and thanks to the thin base, the insulation looks neat.
For the primary winding you need 2x5 turns of wire, that is, 10 turns with a tap from the middle. The work is carried out with a wire with a diameter of 0.7-0.8 mm, and 12 wires are used for each arm. The process is presented more clearly in the following photographs.
The tourniquet is stretched, and 5 turns are evenly wound on both arms, stretching them across the entire ring. The windings must be the same.
The resulting elements have four outputs. The beginning of the first winding must be soldered to the end of the second. The solder location will be a tap for a power voltage of 12 V.
At the next stage of work, the ring must be insulated with fiberglass and covered with a secondary winding.
The secondary winding increases the output voltage. Therefore, when carrying out work you need to be as careful as possible and follow all safety precautions. It is worth remembering that high voltage is dangerous. Installation of the device is carried out only with the power turned off.
The winding of the rings is carried out using a pair of parallel strands of 0.7-0.8 mm wire. The number of turns is about 80 pieces. The wire is distributed evenly throughout the ring. At the final stage, the product is additionally insulated with fiberglass.
When the inverter assembly is completed, you can begin testing it. The device is connected to a battery; for starters, a battery with a voltage of 12 V from an uninterruptible power supply will do. In this case, the “plus” of power will go to the circuit through a 100-watt halogen lamp. It is worth paying attention that this lamp should not be lit before or during work.
After this, you can proceed to checking the field keys for heat generation. With a correctly assembled circuit, it should be practically zero. If there is no input load and the transistors are overheating, then you need to look for a non-working component in the device.
If the testing was successful, you can install the transistors on one common heat sink. For this purpose, special insulating gaskets are used.
The circuit diagram in *.lay format is in the archive file and will be available after downloading.
Such an inverter is designed to produce alternating current 220 V 50 Hz from a car battery or any 12 V battery. The inverter power is about 150 W and can be increased to 300.
The circuit operates as a Push-Pull type converter. The heart of the inverter is the CD4047 microcircuit, which acts as a master oscillator and simultaneously controls field-effect transistors. The latter operate in key mode. Only one of the transistors can be open. If both transistors open at the same time, a short circuit will occur and the transistors will burn out instantly. This can happen due to improper management.
The CD4047 chip, of course, is not designed for high-precision control of field workers, but it copes with this task quite well.
The transformer was taken from a non-working UPS. It is 250-300 W and has a primary winding with a middle point where the plus from the power source is connected.
There are many secondary windings, so you need to find a 220 V network winding. Using a multimeter, the resistance of all taps that are on the secondary circuit is measured. The required leads should have the highest resistance (in the example, about 17 Ohms). All other wires can be bitten off.
It is recommended to check all components before soldering. It is better to select transistors from the same batch with similar characteristics. The capacitor in the frequency-setting circuit must have low leakage and a narrow tolerance. These parameters can be checked with a transistor tester.
A few words about possible replacements in the scheme. Unfortunately, the CD4047 chip has no Soviet analogues, so you need to buy it. “Field switches” can be replaced with any n-channel transistors that have a voltage of 60 V and a current of 35 A. Suitable from the IRFZ line.
The circuit also works great with bipolar transistors at the output, although the power will be much lower than when using field-effect transistors.
Gate limiting resistors can have a resistance of 10 to 100 ohms. It is better to set from 22 to 47 Ohms with a power of 250 mW.
The frequency-setting circuit must be assembled only from those elements indicated in the diagram. It will be finely tuned to 50 Hz.
A correctly assembled device should work immediately. But the first launch must be done with insurance. That is, in place of the fuse according to the diagram, install a resistor with a nominal value of 5-10 Ohms, or a 12 V (5 W) lamp, so as not to blow up the transistors if problems arise.
If the converter is working normally, the transformer makes a sound, and the keys should not heat up at all. If this is the case, then the resistor can be removed and power supplied directly through the fuse.
The average current consumption of an inverter at idle can be between 150 and 300 mA, but this will depend on the power supply and the transformer used.
Next, the output voltage is measured. In the example, the values were from 210 to 260 V. This is within normal limits, since the inverter is not stabilized. Now you can turn on the load, for example, a 60 W lamp. You need to drive the inverter for about 10 seconds, the keys should heat up a little, since they do not yet have heat sinks. The heating on both keys should be uniform. If this is not the case, then look for jambs.
The inverter is equipped with a Remote Control function.
The main power plus is connected to the midpoint of the transformer. But for the inverter to work, it is necessary to apply a low-current plus to the board. This will start the pulse generator.
A few words about installation. As always, everything fits well in the computer's power supply case. Transistors are installed on separate radiators.
If a common heat sink is used, it is necessary to isolate the transistor housings from the radiator. The cooler was connected directly to the 12 V bus.
The biggest drawback of this inverter is the lack of short circuit protection. In this case, the transistors will burn out. To prevent this from happening, a 1 A fuse is needed at the output.
A low-power button supplies plus from the power source to the board, that is, it starts the inverter as a whole.
The power busbars from the transformer are attached directly to the radiators of the transistors.
By connecting a device called an energy meter to the output of the converter, you can make sure that the voltage and frequency are within normal limits. If the frequency differs from 50 Hz, then it must be adjusted using a multi-turn variable resistor, which is present on the board.
During operation, when no load is connected to the output, the transformer is quite noisy. When the load is connected, the noise is negligible. This is all normal, since rectangular pulses are supplied to the transformer.
The resulting inverter is unstabilized, but almost all household appliances are designed to operate in the voltage range from 90 to 280 V.
If the output voltage is higher than 300 V, then it is recommended to connect a 25-watt incandescent light bulb to the output in addition to the main load. This will reduce the output voltage to a small extent.
In principle, it is possible to power commutator motors from a converter, but they heat up 2 times more than when powered from a pure sine wave.
The same thing happens with consumers that have an iron transformer. But it is not recommended to connect asynchronous motors.
The weight of the device is about 2.7 kg. This is a lot when compared with pulse inverters.
Attached files:
How to make a simple Power Bank with your own hands: diagram of a homemade power bank