In this article you can find detailed information step by step instructions for inverter manufacturing AC at 220 V 50 Hz 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 enough large number secondary windings, you will need to use a volt-ohmmeter to measure all 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.
(not TDA1555, but more serious microcircuits) require a power supply with bipolar power supply. And the difficulty here arises not in the UMZCH itself, but in the device that would increase the voltage to the required level, transmitting a good current to the load. This converter is the heaviest part of a homemade car amplifier. However, if you follow all the recommendations, you will be able to assemble a proven PN using this scheme, the diagram of which is given below. To enlarge it, click on it.
The basis of the converter is a pulse generator built on a specialized widespread microcircuit. The generation frequency is set by the value of resistor R3. You can change it to achieve the best stability and efficiency. Let's take a closer look at the design of the TL494 control chip.
Parameters of the TL494 chip
Upp.chip (pin 12) - Upp.min=9V; Upit.max=40V
Permissible voltage at input DA1, DA2 no more than Upit/2
Acceptable parameters of output transistors Q1, Q2:
Uus less than 1.3V;
Uke less than 40V;
Ik.max less than 250mA
The residual collector-emitter voltage of the output transistors is no more than 1.3V.
I consumed by the microcircuit - 10-12mA
Allowable power dissipation:
0.8W at ambient temperature +25C;
0.3W at ambient temperature +70C.
The frequency of the built-in reference oscillator is no more than 100 kHz.
- sawtooth voltage generator DA6; the frequency is determined by the values of the resistor and capacitor connected to the 5th and 6th pins;
- stabilized reference voltage source DA5 with external output (pin 14);
- voltage error amplifier DA3;
- error amplifier for current limit signal DA4;
- two output transistors VT1 and VT2 with open collectors and emitters;
- dead zone comparator DA1;
- comparator PWM DA2;
- dynamic push-pull D-trigger in frequency division mode by 2 - DD2;
- auxiliary logic elements DD1 (2-OR), DD3 (2ND), DD4 (2ND), DD5 (2-OR-NOT), DD6 (2-OR-NOT), DD7 (NOT);
- constant voltage source rated 0.1B DA7;
- DC source with a nominal value of 0.7 mA DA8.
IRFZ44N field-effect transistors swing the load (power transformer). Inductor L1 is wound on a ferite ring with a diameter of 2 cm from a computer power supply. It contains 10 turns of double wire with a diameter of 1 mm which are distributed throughout the ring. If you don’t have a ring, you can wind it on a ferite rod with a diameter of 8 mm and a length of a couple of centimeters (not critical). Board drawing in Lay format - download in .
We warn you, the robotic capability of the converter unit greatly depends on the correct manufacturing of the transformer. It is wound on a 2000NM ferite ring with dimensions of 40*25*11 mm. First you need to round off all the edges with a file and wrap it with linen tape. The primary winding is wound with a bundle that consists of 5 cores 0.7 mm thick and contains 2 * 6 turns, that is, 12. It is wound like this: we take one core and wind it with 6 turns evenly distributed around the ring, then we wind the next one close to the first and so on 5 cores The wires are twisted at the terminals. Then, on the wire-free part of the ring, we begin to wind the second half of the primary winding in the same way. We get two equal windings. After this, we wrap the ring with electrical tape and wind the secondary winding with 1.5mm wire 2*18 turns in the same way as the primary. To ensure that nothing burns out during the first start-up, you need to turn on the transformer primary through a 40-60 W lamp through 100 Ohm resistors in each arm, and everything will hum even with random errors. A small addition: there is a small defect in the filter block circuit; parts c19 r22 should be swapped, since when the phase is rotated, attenuation of the signal amplitude appears on the oscilloscope. In general, this step-up voltage converter can be safely recommended for repetition, since it has already been successfully assembled by many radio amateurs.
To connect household devices to the car’s on-board electrical system, an inverter is required that can increase the voltage from 12 V to 220 V. There are sufficient quantities of them on store shelves, but their price is not encouraging. For those who are a little familiar with electrical engineering, it is possible to assemble a 12-220 volt voltage converter with your own hands. Two simple circuits we'll figure it out.
Converters and their types
There are three types of 12-220 V converters. The first is from 12 V to 220 V. Such inverters are popular among motorists: through them you can connect standard devices - TVs, vacuum cleaners, etc. Reverse conversion - from 220 V to 12 - is required infrequently, usually in rooms with severe operating conditions (high humidity) to ensure electrical safety. For example, in steam rooms, swimming pools or baths. In order not to take risks, the standard voltage of 220 V is reduced to 12, using appropriate equipment.
The third option is, rather, a stabilizer based on two converters. First, the standard 220 V is converted to 12 V, then back to 220 V. This double conversion allows you to have an ideal sine wave at the output. Such devices are necessary for the normal operation of most electronically controlled household appliances. In any case, during installation it is strongly recommended to power it through just such a converter - its electronics are very sensitive to the quality of power, and replacing the control board costs about half the boiler.
Pulse converter 12-220V 300 W
This circuit is simple, the parts are available, most of them can be removed from a computer power supply or purchased at any radio store. The advantage of the circuit is its ease of implementation, the disadvantage is the non-ideal sine wave at the output and the frequency is higher than the standard 50 Hz. That is, devices that require power supply cannot be connected to this converter. You can directly connect not particularly sensitive devices to the output - incandescent lamps, iron, soldering iron, phone charger, etc.
The presented circuit in normal mode produces 1.5 A or pulls a load of 300 W, at a maximum of 2.5 A, but in this mode the transistors will noticeably heat up.
The circuit was built on the popular TLT494 PWM controller. Field-effect transistors Q1 Q2 should be placed on radiators, preferably separate ones. When installing on one radiator, place an insulating gasket under the transistors. Instead of the IRFZ244 indicated in the diagram, you can use IRFZ46 or RFZ48, which are similar in characteristics.
The frequency in this 12 V to 220 V converter is set by resistor R1 and capacitor C2. The values may differ slightly from those shown in the diagram. If you have an old non-working power supply for your computer, and it contains a working output transformer, you can put it in the circuit. If the transformer is not working, remove the ferrite ring from it and wind the windings with copper wire with a diameter of 0.6 mm. First, the primary winding is wound - 10 turns with the output from the middle, then, on top - 80 turns of the secondary.
As already said, such a 12-220 V voltage converter can only work with a load that is insensitive to power quality. To be able to connect more demanding devices, a rectifier is installed at the output, the output voltage of which is close to normal (diagram below).
The circuit shows high-frequency diodes of the HER307 type, but they can be replaced with the FR207 or FR107 series. It is advisable to select containers of the specified size.
Inverter on a chip
This 12-220 V voltage converter is assembled on the basis of a specialized KR1211EU1 microcircuit. This is a generator of pulses that are removed from outputs 6 and 4. The pulses are antiphase, with a short time interval between them to prevent the simultaneous opening of both keys. The microcircuit is powered by a voltage of 9.5 V, which is set by a parametric stabilizer on a D814V zener diode.
Also in the circuit there are two high-power field-effect transistors - IRL2505 (VT1 and VT2). They have a very low open resistance of the output channel - about 0.008 Ohms, which is comparable to the resistance of a mechanical key. Permissible direct current is up to 104 A, pulsed current is up to 360 A. Such characteristics actually make it possible to obtain 220 V with a load of up to 400 W. Transistors must be installed on radiators (with a power of up to 200 W it is possible without them).
The pulse frequency depends on the parameters of resistor R1 and capacitor C1; capacitor C6 is installed at the output to suppress high-frequency surges.
It is better to take a ready-made transformer. In the circuit, it is turned on in reverse - the low-voltage secondary winding serves as the primary, and the voltage is removed from the high-voltage secondary.
Possible replacements in the element base:
- The D814V zener diode indicated in the circuit can be replaced with any one that produces 8-10 V. For example, KS 182, KS 191, KS 210.
- If there are no capacitors C4 and C5 of type K50-35 at 1000 μF, you can take four 5000 μF or 4700 μF and connect them in parallel,
- Instead of an imported capacitor C3 220m, you can supply a domestic one of any type with a capacity of 100-500 µF and a voltage of at least 10 V.
- Transformer - any with a power from 10 W to 1000 W, but its power must be at least twice the planned load.
When installing circuits for connecting a transformer, transistors and connecting to a 12 V source, it is necessary to use large cross-section wires - the current here can reach high values (with a power of 400 W up to 40 A).
Inverter with pure sine wave output
The circuits of daytime converters are complex even for experienced radio amateurs, so making them yourself is not at all easy. An example of the simplest circuit is below.
In this case, it is easier to assemble such a converter from ready-made boards. How - watch the video.
The next video shows how to assemble a 220 volt converter with pure sine wave. Only the input voltage is not 12 V, but 24 V.
And this video just tells you how you can change the input voltage, but still get the required 220 V at the output.
A 12V/220V inverter is a necessary thing on a household. Sometimes it’s simply necessary: the network, for example, has disappeared, and the phone is dead and there’s meat in the refrigerator. Demand determines supply: for ready-made models of 1 kW or more, from which you can power any electrical appliances, you will have to pay somewhere from $150. Possibly over $300. However, making a voltage converter with your own hands in our time is a task accessible to everyone who knows how to solder: assemble it from ready set the component will cost three to four times less + a little work and metal from scrap trash. If there is one for car batteries, you can generally spend 300-500 rubles. And if you also have basic amateur radio skills, then, after rummaging around in stashes, it is quite possible to make a 12V DC/220V AC 50Hz inverter for 500-1200 W for nothing. Let's consider the possible options.
Options: Global
A 12-220 V voltage converter to power a load up to 1000 W or more can generally be made independently in the following ways (in order of increasing costs):
- Place a ready-made unit in a case with a heat sink from Avito, Ebay or AliExpress. Search for "inverter 220" or "inverter 12/220"; you can immediately add the required power. It will cost approx. half the price of the same factory one. No electrical skills required, but - see below;
- Assemble the same one from the kit: printed circuit board + “scattered” components. It can be purchased there, but diy is added to the request, which means self-assembly. Price still approx. 1.5 times lower. You need basic skills in radio electronics: using a multimeter, knowledge of the wiring (pinouts) of the terminals of active elements or the ability to look for them, the rules for including polar components (diodes, electrolytic capacitors) in the circuit and the ability to determine what current and what cross-section wires are needed;
- Adapt a computer uninterruptible power supply (UPS, UPS) to the inverter. A working used UPS without a standard battery can be found for 300-500 rubles. You don’t need any skills - you simply connect the car battery to the UPS. But you will have to charge it separately, also see below;
- Choose a conversion method, a diagram (see below) in accordance with your needs and the availability of parts, calculate and assemble completely yourself. It may be completely free, but in addition to basic electronic skills you will need the ability to use some special measuring instruments(also see below) and perform simple engineering calculations.
From a finished module
Assembly methods according to paragraphs. 1 and 2 are actually not that simple. The housings of ready-made factory inverters also serve as heat sinks for powerful transistor switches inside. If you take a “semi-finished product” or “loose”, then there will be no housing for them: given the current cost of electronics, manual labor and non-ferrous metals, the difference in prices is explained precisely by the absence of the second and, possibly, the third. That is, you will have to make a radiator for powerful keys yourself or look for a ready-made aluminum one. Its thickness at the location where the keys are installed should be at least 4 mm, and the area for each key should be at least 50 square meters. see for each kW of power output; with blowing from a 12 V computer fan-cooler 110-130 mA – from 30 sq. cm*kW*key.
For example, there are 2 keys in a set (module) (they can be seen, they stick out from the board, see on the left in the figure); modules with keys on the radiator (on the right in the figure) are more expensive and are designed for a certain, usually not very high power. There is no cooler, the power required is 1.5 kW. This means you need a radiator of 150 sq. see. In addition to this, there are also installation kits for keys: insulating heat-conducting gaskets and fittings for mounting screws - insulating cups and washers. If the module has thermal protection (there will be some other piece sticking out between the keys - a thermal sensor), then a little thermal paste to glue it to the radiator. Wires - of course, see below.
From UPS
The 12V DC/220V AC 50Hz inverter, to which you can connect any devices within the permissible power limit, is made from a computer UPS quite simply: the standard wires to “your” battery are replaced with long ones with clamps for the car battery terminals. The wire cross-section is calculated based on the permissible current density of 20-25 A/sq. mm, see also below. But because of a non-standard battery, problems can arise - with it, and it is more expensive and more necessary than a converter.
UPS also uses lead-acid batteries. This is today the only widely available secondary chemical power source that is capable of regularly delivering large currents (extra currents) without being completely “killed” in 10-15 charge-discharge cycles. In aviation, silver-zinc batteries are used, which are even more powerful, but they are monstrously expensive, are not widely available, and their service life is negligible by everyday standards - approx. 150 cycles.
The discharge of acid batteries is clearly monitored by the voltage on the bank, and the UPS controller will not allow the “foreign” battery to be discharged beyond measure. But in standard UPS batteries the electrolyte is gel, while in car batteries it is liquid. The charging modes in both cases are significantly different: the same currents cannot be passed through the gel as through a liquid, and in a liquid electrolyte, if the charge current is too low, the mobility of the ions will be low and not all of them will return to their places in the electrodes. As a result, the UPS will chronically undercharge the car battery; it will soon become sulfated and become completely unusable. Therefore, a battery charger is required for the inverter on the UPS. You can make it yourself, but that's another topic.
Battery and power
The suitability of the converter for a particular purpose also depends on the battery. A boost voltage inverter does not take energy for consumers from the “dark matter” of the Universe, black holes, the holy spirit, or anywhere else just like that. Only from the battery. And from it he will take the power supplied to consumers, divided by the efficiency of the converter itself.
If you see “6800W” or more on the body of a branded inverter, believe your eyes. Modern electronics make it possible to fit even more powerful devices into the volume of a cigarette pack. But let’s say we need a load power of 1000 W, and we have a regular 12 V 60 A/h car battery at our disposal. The typical value of inverter efficiency is 0.8. This means that it will take approx. 100 A. For such a current, wires with a cross-section of 5 square meters are also needed. mm (see above), but that’s not the main thing here.
Car enthusiasts know: if you ran the starter for 20 minutes, buy it new battery. True, new machines have time limits for its operation, so perhaps they don’t know. And certainly not everyone knows that the starter of a car, once spun up, takes a current of approx. 75 A (within 0.1-0.2 s at startup - up to 600 A). The simplest calculation - and it turns out that if the inverter does not have automatic equipment that limits the battery discharge, then ours will run out completely in 15 minutes. So choose or design your converter taking into account the capabilities of the existing battery.
Note: This implies a huge advantage of 12/220 V converters based on computer UPSs - their controller will not allow the battery to drain completely.
The service life of acid batteries does not noticeably decrease if they are discharged with a 2-hour current (12 A for 60 A/h, 24 A for 120 A/h and 42 A for 210 A/h). Taking into account the conversion efficiency, this gives a permissible long-term load power of approx. 120 W, 230 W and 400 W respectively. For 10 min. load (for example, to power a power tool), it can be increased by 2.5 times, but after this the ABC must rest for at least 20 minutes.
Overall, the result is not entirely bad. Of the ordinary household power tools, only the grinder can take 1000-1300 W. The rest, as a rule, cost up to 400 W, and screwdrivers up to 250 W. A refrigerator from a 12 V 60 A/h battery will work through an inverter for 1.5-5 hours; quite enough to take the necessary measures. Therefore, making a 1 kW converter for a 60 A/h battery makes sense.
What will be the output?
In order to reduce the weight and size of the device, with rare exceptions (see below), voltage converters operate at increased frequencies from hundreds of Hz to units and tens of kHz. No consumer will accept a current of such frequency, and the loss of its energy in conventional wiring will be enormous. Therefore, inverters 12-200 are built for the following output voltage. types:
- Constant rectified 220 V (220V AC). Suitable for powering telephone chargers, most power supplies (PS) of tablets, incandescent lamps, fluorescent housekeepers and LED lamps. With a power of 150-250 W, they are perfect for hand-held power tools: their power consumption is about DC decreases slightly and torque increases. Not suitable for switching power supplies (UPS) of TVs, computers, laptops, microwave ovens, etc. with a power of more than 40-50 W: these necessarily have the so-called. a starting unit, for the normal operation of which the mains voltage must periodically pass through zero. Unsuitable and dangerous for devices with power transformers on iron and AC electric motors: stationary power tools, refrigerators, air conditioners, most Hi-Fi audio, food processors, some vacuum cleaners, coffee makers, coffee grinders and microwave ovens (for the latter - due to the presence of a rotation motor table).
- Modified sine wave (see below) - suitable for any consumers, except for Hi-Fi audio with a UPS, other devices with a UPS from 40-50 W (see above) and, often local security systems, home weather stations, etc. with sensitive analog sensors.
- Pure sinusoidal - suitable without restrictions, except for power, for any electricity consumers.
Sine or pseudosine?
In order to increase efficiency, voltage conversion is carried out not only at higher frequencies, but also with heteropolar pulses. However, powering many consumer devices with a sequence of different polarity rectangular pulses(the so-called meander) is impossible: large surges on the meander fronts with even a slightly reactive load will lead to large energy losses and can cause a consumer malfunction. However, it is also impossible to design the converter for sinusodal current - the efficiency will not exceed approx. 0.6.
A quiet, but significant revolution in this industry occurred when microcircuits were developed specifically for voltage inverters, forming the so-called. a modified sinusoid (on the left in the figure), although it would be more correct to call it pseudo-, meta-, quasi-, etc. sinusoid. The current shape of the modified sinusoid is stepped, and the pulse fronts are prolonged (the meander fronts are often not visible at all on the screen of a cathode-ray oscilloscope). Thanks to this, consumers with transformers on iron or noticeable reactivity (asynchronous electric motors) “understand” the pseudosine wave “as real” and work as if nothing had happened; Hi-Fi audio with a network transformer on hardware can be powered by a modified sine wave. In addition, the modified sinusoid can be sufficiently in simple ways smooth out to “almost real”, the differences from the pure one on an oscilloscope are barely noticeable by eye; Converters of the “Pure Sine” type are not much more expensive than conventional ones, on the right in Fig.
However, it is not advisable to run devices with capricious analog components and UPSs from a modified sine wave. The latter are extremely undesirable. The fact is that the middle platform of the modified sinusoid is not a pure zero voltage. The UPS starting unit from a modified sine wave does not operate clearly and the entire UPS may not exit the startup mode into operating mode. The user sees this at first as ugly glitches, and then smoke comes out of the device, as in the joke. Therefore, the devices in the UPS must be powered from Pure Sine type inverters.
We make the inverter ourselves
So, for now it is clear that it is best to make an inverter for an output of 220 V 50 Hz, although we will also remember about the AC output. In the first case, to control the frequency you will need a frequency meter: the norm for fluctuations in the frequency of the power supply network is 48-53 Hz. AC electric motors are especially sensitive to its deviations: when the frequency of the supply voltage reaches the tolerance limits, they heat up and “go away” from the rated speed. The latter is very dangerous for refrigerators and air conditioners; they can irreparably fail due to depressurization. But we don’t need to buy, rent or beg for a loan an accurate and multifunctional electronic frequency meter - we don’t need its accuracy. Either an electromechanical resonant frequency meter (pos. 1 in the figure) or a pointer of any system, pos. 2:
Both are inexpensive, sold on the Internet, and in large cities in electrical specialty stores. An old resonant frequency meter can be found at the iron bazaar, and one or the other, after setting up the inverter, is very suitable for monitoring the network frequency in the house - the meter does not respond to connecting them to the network.
50 Hz from computer
In most cases, 220 V 50 Hz power is required by consumers that are not particularly powerful, up to 250-350 W. Then the basis for a 12/220 V 50 Hz converter can be a UPS from an old computer - if, of course, one is lying around in the trash or someone is selling it cheap. The power delivered to the load will be approx. 0.7 from the rated UPS. For example, if “250W” is written on its body, then devices up to 150-170 W can be connected without fear. You need more - you must first test it on a load of incandescent lamps. It lasted 2 hours – it can deliver such power for a long time. How to make a 12V DC/220V AC 50Hz inverter from a computer power supply, see the video below.
Video: a simple 12-220 converter from a computer power supply
Keys
Let's say there is no computer UPS or you need more power. Then the choice of key elements becomes important: they must switch high currents with minimal switching losses, be reliable and affordable. In this regard, bipolar transistors and thyristors are confidently becoming a thing of the past in this area of application.
The second revolution in the inverter business is associated with the advent of powerful field-effect transistors (“field transistors”), the so-called. vertical structure. However, they have revolutionized the entire technology of power supply for low-power devices: it is becoming increasingly difficult to find a transformer on iron in household appliances.
The best of the high-power field devices for voltage converters are insulated gate induced channel (MOSFET), e.g. IFR3205, left in the figure:
Due to the negligible switching power, the efficiency of an inverter with a DC output on such transistors can reach 0.95, and with an AC 50 Hz output 0.85-0.87. Analogues of MOSFET with a built-in channel, e.g. IFRZ44, provide lower efficiency, but are much cheaper. A pair of one or the other allows you to bring the power in the load to approx. 600 W; both can be paralleled without problems (on the right in the figure), which makes it possible to build inverters with a power of up to 3 kW.
Note: The power loss of switching switches with a built-in channel when operating on a significantly reactive load (for example, an asynchronous electric motor) can reach 1.5 W per switch. Keys with an induced channel are free from this drawback.
TL494
The third element that made it possible to bring voltage converters to their current state is the specialized TL494 microcircuit and its analogues. All of them are a pulse-width modulation (PWM) controller that generates a modified sine wave signal at the outputs. The outputs are multi-polar, which allows you to control pairs of keys. The reference conversion frequency is set by one RC circuit, the parameters of which can be changed within wide limits.
When is a permanent job enough?
The circle of 220 V DC consumers is limited, but it is they who need autonomous power supply not only for emergency situations. For example, when working with power tools on the road or in the far corner of your own site. Or it is always present, say, at the emergency lighting of the entrance to the house, hallway, corridor, local area from a solar battery that recharges the battery during the day. The third typical case is charging your phone on the go from the cigarette lighter. Here the output power is needed very little, so the inverter can be made with just 1 transistor according to the relaxation generator circuit, see next. video clip.
Video: boost converter on one transistor
Already for 2-3 meals LED light bulbs need more power. When trying to “squeeze” it, the efficiency of blocking generators drops sharply, and you have to switch to circuits with separate timing elements or full internal inductive feedback; they are the most economical and contain the least number of components. In the first case, to switch one switch, the self-induction EMF of one of the transformer windings is used together with a timing circuit. In the second, the frequency-setting element is the step-up transformer itself due to its own time constant; its value is determined primarily by the phenomenon of self-induction. Therefore, both inverters are sometimes called self-induction converters. Their efficiency, as a rule, is no higher than 0.6-0.65, but, firstly, the circuit is simple and does not require adjustment. Secondly, the output voltage is more trapezoidal than square wave; “demanding” consumers “understand” it as a modified sine wave. Disadvantage: field switches in such converters are practically inapplicable, because often fail due to voltage surges on the primary winding during switching.
An example of a circuit with external timing elements is given in pos. 1 pic:
The author of the design was unable to squeeze more than 11 W out of it, but apparently, he confused ferrite with carbonyl iron. In any case, the armored (cup) magnetic circuit in his own photo (see figure on the right) is in no way ferrite. It looks more like an old carbonyl one, oxidized on the outside with time, see fig. right. It is better to wind the transformer for this inverter on a ferrite ring with a ferrite cross-sectional area of 0.7-1.2 square meters. cm. The primary winding should then contain 7 turns of wire with a copper diameter of 0.6-0.8 mm, and the secondary winding should contain 57-58 turns of wire 0.3-0.32 mm. This is for straightening with doubling, see below. For “pure” 220 V - 230-235 turns of wire 0.2-0.25. In this case, when replacing KT814 with KT818, this inverter will deliver power up to 25-30 W, which is enough for 3-4 LED lamps. When replacing KT814 with KT626, the load power will be approx. 15 W, but the efficiency will increase. In both cases, the key radiator is from 50 square meters. cm.
At pos. 2 shows a diagram of the “antediluvian” converter 12-220 with separate windings feedback. It's not that archaic. First, the output voltage under load is trapezoidal with rounded fractures and no spikes. It's even better than a modified sine wave. Secondly, this converter can be designed without any modifications in the circuit for a power of up to 300-350 W and a frequency of 50 Hz, then a rectifier is not needed, you just need to install VT1 and VT2 on radiators from 250 kW. see each. Thirdly, it protects the battery: when overloaded, the conversion frequency drops, the output power decreases, and if you load it even more, the generation stops. That is, to avoid over-discharging the battery, no automation is required.
The procedure for calculating this inverter is given in the scan in Fig.:
The key quantities in it are the conversion frequency and the working induction in the magnetic circuit. The conversion frequency is selected based on the material of the available core and the required power:
| Type Magnetic cores | Induction/conversion frequency | |||
|---|---|---|---|---|
| Up to 50 W | 50-100 W | 100-200 W | 200-350 W | |
| “Power” iron from power transformers with a thickness of 0.35-0.6 mm | 0.5 T/(50-1000)Hz | 0.55 T/(50-400)Hz | 0.6 T/(50-150)Hz | 0.7 T/(50-60)Hz |
| “Sound” iron from UMZCH output transformers with a thickness of 0.2-0.25 mm | 0.4 T/(1000-3000)Hz | 0.35 T/(1000-2000)Hz | - | - |
| “Signal” iron from signal transformers with a thickness of 0.06-0.15 mm (not permalloy!) | 0.3 T/(2000-8000)Hz | 0.25 T/(2000-5000)Hz | - | - |
| Ferrite | 0.15 T/(5-30) kHz | 0.15 T/(5-30) kHz | 0.15 T/(5-30) kHz | 0.15 T/(5-30) kHz |
This “omnivorousness” of ferrite is explained by the fact that its hysteresis loop is rectangular and the working induction is equal to the saturation induction. The decrease in the calculated values of induction in steel magnetic cores compared to typical ones is caused by a sharp increase in switching losses of non-sinusoidal currents as it increases. Therefore, from the core of the power transformer of the old 270 W “coffin” TV in this 50 Hz converter it will be possible to remove no more than 100-120 W. But - without fish, there is cancer in fish.
Note: If you have a steel magnetic core with a deliberately oversized cross-section, do not squeeze the power out of it! Let the induction be better - the efficiency of the converter will increase, and the shape of the output voltage will improve.
Straightening
It is better to rectify the output voltage of these inverters using a circuit with parallel voltage doubling (item 3 in the figure with diagrams): the components for it will cost less, and the power losses on a non-sinusoidal current will be less than in a bridge. Capacitors should be taken “power”, designed for high reactive power (designated PE or W). If you put “sound” ones without these letters, they may simply explode.
50 Hz? It's very simple!
A simple 50 Hz inverter (item 4 in the figure above with diagrams) is an interesting design. For some types of standard power transformers, the intrinsic time constant is close to 10 ms, i.e. half a period of 50 Hz. By adjusting it with timing resistors, which will also act as limiters for the control current of the switches, you can immediately obtain a smoothed 50 Hz square wave at the output without complex formation circuits. Transformers TP, TPP, TN for 50-120 W are suitable, but not just any kind. You may have to change the resistor values and/or connect 1-22 nF capacitors in parallel with them. If the conversion frequency is still far from 50 Hz, it is useless to disassemble and rewind the transformer: the magnetic circuit glued with ferromagnetic glue will fluff up, and the parameters of the transformer will deteriorate sharply.
This inverter is a weekend dacha converter. It will not drain the car battery for the same reasons as the previous one. But it is enough to illuminate a house with a veranda with LED lamps and a TV or a vibration pump in a well. The conversion frequency of an established inverter when the load current changes from 0 to maximum does not exceed the technical norms for power supply networks.
The windings of the original transformer are routed like this. In typical power transformers, there is an even number of secondary windings for 12 or 6 V. Two of them are “set aside”, and the rest are soldered in parallel into groups of an equal number of windings in each. Next, the groups are connected in series so that you get 2 half-windings of 12 V each, this will be a low-voltage (primary) winding with a midpoint. Of the remaining low-voltage windings, one is connected in series with the 220 V mains winding; this will be the step-up winding. An additive is needed because... The voltage drop across switches made of bipolar composite transistors, together with its losses in the transformer, can reach 2.5-3 V, and the output voltage will be underestimated. Additional winding will bring it up to normal.
DC from the chip
The efficiency of the described converters does not exceed 0.8, and the frequency varies noticeably depending on the load current. The maximum load power is less than 400 W, so it’s time to think about modern circuit solutions.
The circuit of a simple converter 12 V DC/220 V DC for 500-600 W is shown in the figure:
Its main purpose is to power hand-held power tools. Such a load is not demanding on the quality of the supplied voltage, so the keys are taken cheaper; IFRZ46, 48 are also suitable. The transformer is wound on ferrite with a cross-section of 2-2.5 square meters. cm; A power transformer core from a computer UPS is suitable. Primary winding - 2x5 turns of a bundle of 5-6 winding wires with a copper diameter of 0.7-0.8 mm (see below); secondary - 80 turns of the same wire. No adjustment is required, but there is no monitoring of battery discharge, so during operation you need to attach a multimeter to its terminals and do not forget to look at it (the same applies to all other homemade voltage inverters). If the voltage drops to 10.8 V (1.8 V per cell) - stop, turn off! It dropped to 1.75 V per cell (10.5 V for the entire battery) - this is already sulfation!
How to wind a transformer on a ring
On quality characteristics of an inverter, in particular, its efficiency is quite strongly influenced by the stray field of its transformer. The fundamental solution to reduce it has long been known: the primary winding, which “pumps” the magnetic circuit with energy, is placed close to it; secondary ones above it in descending order of their power. But technology is such a thing that theoretical principles in specific designs sometimes have to be turned inside out. One of Murphy's laws states approx. so: if the piece of hardware still doesn’t want to work as it should, try doing the opposite in it. This fully applies to a high-frequency transformer on a ferrite ring magnetic core with windings made of relatively thick rigid wire. Wind the voltage converter transformer on a ferrite ring like this:
- The magnetic circuit is insulated and, using a winding shuttle, a secondary step-up winding is wound onto it, laying the turns as tightly as possible, pos. 1 in Fig.:
- Tightly wrap the secondary part with tape, pos. 2.
- Prepare 2 identical wire harnesses for the primary winding: wind the number of turns of half the low-voltage winding with a thin unusable wire, remove it, measure the length, cut off the required number of winding wire segments with a reserve and assemble them into bundles.
- Additionally, the secondary winding is insulated until a relatively flat surface is obtained.
- Wind the “primary” with 2 bundles at once, arranging the wires of the bundles with tape and evenly distributing the turns over the core, pos. 3.
- Call the ends of the bundles and connect the beginning of one to the end of the other, this will be the middle point of the winding.
Note: on electric circuit diagrams the beginnings of the windings, if relevant, are indicated by a dot.
50 Hz smoothed
A modified sine wave from a PWM controller is not the only way to get 50 Hz at the inverter output, suitable for connecting any household electricity consumers, and it wouldn’t hurt to “smooth” that too. The simplest of them is the good old iron transformer; it “irons” well due to its electrical inertia. True, finding a magnetic core for more than 500 W is becoming increasingly difficult. Such an isolation transformer is switched on to the low-voltage output of the inverter, and a load is connected to its step-up winding. By the way, most computer UPSs are built according to this scheme, so they are quite suitable for this purpose. If you wind the transformer yourself, then it is calculated similarly to the power one, but with a trace. features:
- The initially determined value of the working induction is divided by 1.1 and applied in all further calculations. This is necessary in order to take into account the so-called. non-sinusoidal voltage shape factor Kf; for a sinusoid Kf=1.
- The step-up winding is first calculated as a 220 V mains winding for a given power (or determined by the parameters of the magnetic circuit and the value of the working induction). Then the found number of turns is multiplied by 1.08 for powers up to 150 W, by 1.05 for powers of 150-400 W and by 1.02 for powers of 400-1300 W.
- Half of the low-voltage winding is calculated as a secondary voltage of 14.5 V for bipolar switches or with a built-in channel and 13.2 V for switches with an induced channel.
Examples of circuit solutions for 12-200 V 50 Hz converters with an isolation transformer are shown in the figure:
On the one on the left, the keys are controlled by the so-called master oscillator. a “soft” multivibrator, it already generates a meander in blocked fronts and smoothed fractures, so no additional smoothing measures are required. The instability of the frequency of a soft multivibrator is higher than that of a regular one, so to adjust it you need a potentiometer P. With keys on the KT827, you can remove power up to 200 W (radiators from 200 sq. cm without blowing). Keys on KP904 from old junk or IRFZ44 allow you to increase it to 350 W; single ones on IRF3205 up to 600 W, and paired ones on them up to 1000 W.
An inverter 12-220 V 50 Hz with a master oscillator on TL494 (on the right in the figure) maintains the frequency firmly in all conceivable operating conditions. To more effectively smooth a pseudosinusoid, the so-called phenomenon is used. indifferent resonance, in which the phase relationships of currents and voltages in the oscillatory circuit become the same as with acute resonance, but their amplitudes do not increase noticeably. Technically, this can be solved simply: a smoothing capacitor is connected to the boost winding, the capacitance value of which is selected according to the best shape of the current (not voltage!) under load. To control the shape of the current, a 0.1-0.5 Ohm resistor is connected to the load circuit at a power of 0.03-0.1 of the rated value, to which an oscilloscope with a closed input is connected. The smoothing capacitance does not reduce the efficiency of the inverter, but you cannot use computer programs for simulating low-frequency oscilloscopes to configure it, because the input of the sound card they use is not designed for an amplitude of 220x1.4 = 310 V! The keys and powers are the same as before. case.
A more advanced 12-200 V 50 Hz converter circuit is shown in Fig.:
It uses complex compound keys. To improve the quality of the output voltage, it uses the fact that the emitter of planar epitaxial bipolar transistors is doped much more heavily than the base and collector. When TL494 applies a closing potential, for example, to the base of VT3, its collector current will stop, but due to the resorption of the emitter space charge, it will slow down the closing of T1 and voltage surges from the self-induction emf Tr will be absorbed by circuits L1 and R11C5; they will “tilt” the fronts more. The output power of the inverter is determined by the overall power Tr, but not more than 600 W, because It is impossible to use paired powerful switches in this circuit - the spread in the value of the gate charge of MOSFET transistors is quite significant and the switching of the switches will be unclear, which is why the shape of the output voltage may even worsen.
Choke L1 is 5-6 turns of wire with a diameter of 2.4 mm on copper, wound on a piece of ferrite rod with a diameter of 8-10 m and a length of 30-40 mm in increments of 3.5-4 mm. The throttle magnetic circuit must not be short-circuited! Setting up a circuit is quite a painstaking task and requires a lot of experience: you need to select L1, R11 and C5 according to the best shape of the output current under load, as in the previous one. case. But Hi-Fi, powered from this converter, remains “hi-fi” to the most demanding ears.
Is it possible without a transformer?
Already the winding wire for a powerful 50 Hz transformer will cost a pretty penny. Magnetic cores from “coffin” transformers up to 270 W overall are more or less available, but in an inverter you cannot squeeze more than 120-150 W out of this, and the efficiency will be 0.7 at best, because “coffin” magnetic cores are wound from a thick tape, the eddy current losses in which are large at non-sinusoidal voltage on the windings. Finding an SL magnetic core made of a thin strip capable of delivering more than 350 W at an induction of 0.7 Tesla is generally problematic, it will be expensive, and the entire converter will be huge and heavy-lifting. UPS transformers are not designed for frequent operation in long-term mode - they heat up and their magnetic circuits in inverters degrade quite quickly - the magnetic properties deteriorate greatly, the power of the converter drops. Is there a way out?
Yes, and this solution is often used in branded converters. This is an electric bridge made of keys on high-voltage power field effect transistors with a breakdown voltage of 400 V and a drain current of more than 5 A. Suitable from the primary circuits of computer UPSs, and from old trash - KP904, etc.
The bridge is powered by a constant 220 V DC from a simple 12-220 inverter with rectification. The arms of the bridge open in pairs, crosswise, alternately, and the current in the load included in the diagonal of the bridge changes direction; The control circuits of all keys are galvanically separated. In industrial designs, the keys are controlled by special devices. IC with optocoupler isolation, but in amateur conditions both can be replaced with an additional low-power inverter 12 V DC - 12 V 50 Hz, powered by a small transformer on hardware, see fig. The magnetic core for it can be taken from a Chinese market low-power power transformer. Due to its electrical inertia, the quality of the output voltage is even better than a modified sine wave.
Comments (40):
#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 from charging will work, special role the transistors will still play. 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 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: led lamp from the same battery, with the same light output, it 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 battery perform 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.