It seems that every first teslastor has already assembled a "kacher". Every second it exploded, and every fourth tries to find out from me why it exploded. Therefore, today we will try to work on the errors in the kachar circuit.
The classic scheme looks like this:
It works quite simply - the current from the 220V network passes through the choke L1, is rectified by the diode D1 and the capacitor C1.
Resistors R1 and R2 are selected so that the transistor is at the opening threshold. When it opens, the current begins to flow through the L2 coil (this is the primary winding), while oscillations begin in the L3 resonator. Oscillations close the transistor (for this you need to choose the correct phasing of the windings), and then open it again and the circuit “starts up”.
Zener diode D2 protects the gate of the transistor from high voltage, and at the same time. provides a path for the secondary current to earth.
It would seem like a cool scheme! Very simple and even works. But, it also has several disadvantages.
Control
Especially for this article, I collected a classic cacher and it turned out that the current in the L3 resonator grows rather slowly. At the same time, the transistor is in the linear region (and is not open or closed), which is why it emits a lot of heat, and the transistor turns into a stove. It is especially cruel for the transistor when the oscillations do not begin - all the power supplied is allocated to it.To prevent the transistor from being in linear mode, we need a "real" driver. I used a ready-made IC, but I'm pretty sure that just a complementary pair of bipolar transistors can be used.
At the same time, it was necessary to add transformer power. I tried to make a self-powered circuit, but nothing good came of it. Our cacher began to look like this:
Here, resistor R1 provides a start by switching the output of the transistor at 50Hz. This circuit began to heat up much less, it starts without any configuration and works very stably.
The big drawback of such a start system is that if something goes wrong and the oscillations in the winding stop, the transistor will remain open and burn out like in a classic quality, a choke or some more intelligent start system can help, but we don't bother we will :)
Emissions
There are very large voltage spikes at the drain of the transistor. They appear due to the fact that when the transistor turns off, the primary winding, like any inductance, continues to maintain current through it. The current has nowhere to go and it charges the drain-source capacitance to a very high voltage.But we were lucky - MOSFET transistors, when the maximum voltage is exceeded, work like zener diodes - they break through, but, at the same time, they are not damaged. To limit the current through the transistor, the choke L1 serves.
This solution has two disadvantages -
- The transistor heats up for all the power that is not consumed (that is, the power for the power passed by the choke minus the power of the streamer), and it can be used as a boiler.
- The chokes themselves are quite large and you need to get a lot of them for decent power.
When the transistor is turned off, the primary winding charges the capacitor C4 (current flows along the L2-C4-D6 path), and when turned on, C4 discharges along the D7-\u003e L1-\u003e C4-\u003e Q1 path. As a result, the voltage at the drain of Q1 reaches 2x supply voltages, which is already quite acceptable.
Naturally, small needles above the supply voltage can slip, but they can be caught with a conventional suppressor:
Safety
Such a cacher is a very dangerous thing. Its streamer is not disconnected from the network in any way, consider it connected to the phase. People here are very fond of climbing the streamer with their hands, and they can very easily get terminated. For decoupling, you can try to use a Y2 capacitor, but since it does not work in the normal mode, no one can guarantee that it will not be punched, therefore, it remains only to use a current transformer to pick up the feedback signal:
Alternatively, you can run the cacher through a 220/220 isolation transformer as I did.
Tests
Much can still be improved in this small circuit, but these changes are enough for the circuit to start quite well, nothing warms up and everything works stably. I mocked it all up in "best breadboarding tradition" with an IRFP450 transistor, Tesla QCW coil, poop and twigs.The streamer immediately turned out to be of the order of the length of the secondary winding. Naturally, it is impossible to supply 220v directly to the IRFP450; it is designed for only 500v, and at 220v it will have 700v, therefore, it was necessary to power it through the LATR.
Coil L1 is wound on a frame from solder with a diameter of 2 cm, contains 20 turns of wire with a diameter of 0.5 mm, without a core.
conclusions
On the one hand, we got good results, and if we put the kaike-realties transistors more voltistically, this cacher can be connected directly to the network and get quite large streamers.On the other hand, the circuit turned out to be not much simpler than the classical half-bridge circuit, but, at the same time, it has safety problems, the load on the components is much greater here, and there are also a couple of unresolved points - for example, failure with a short circuit of the secondary winding. In general, if you want better results than in the picture, or you want a reliable tesla, I would not waste time on a kacher.
I welcome everyone. Before starting, a little history of what kind of Kacher Brovina is this
Today we will talk about Kachera Brovin on a field-effect transistor. The highlight of this unit will be the ability to regulate high-voltage discharges emanating from the terminal.
Options:
Consumption 3.4 amperes
Supply voltage 220-250 volts
Power 800 watts
I'll start with a diagram.
Principle of operation
The diagram shows that the device consists of three parts: a power supply unit, a control unit (breaker) and the cacher itself. The control unit is used to adjust the frequency and duty cycle of pulses that go to T1 (mosfet), which, in time with the frequency, then opens and closes, opening the transition between the drain-source. Thus, a current begins to flow through the open transition, closing the circuit of the kicker to the power supply, and a pulse is obtained. In this short period of time, a spark runs through the terminal. I will describe how it all works in a simple way: a voltage appeared on the power supply (the current went in 2 directions to the breaker and to T1), the breaker turned on, gave a pulse to the gate T1, the gate opened the transition, current flowed through the cacher and the circuit closed.
What to replace with what and how to make it work?
Control unit (breaker).
The breaker can be replaced with any generator of rectangular pulses, but in this article it is one so we will consider it in more detail. All ratings of parts except microcircuits can be changed by 10-30%, but the circuit will work differently, I recommend making the generator frequency up to 150 Hz.
This formula determines the frequency: 
.
Power Supply.
The entire device is powered from a 220 volt network; a 5 amp fuse is placed for protection. Actually the cacher is powered by 310 volts (220 volts rectified), I recommend taking the diode bridge for a current of at least 10 amperes and a voltage of at least 500 volts. The breaker is powered separately through a 220/12 volt decoupling transformer via a 1 amp 50 volt diode bridge and is shunted by a capacitor.
Kacher.
As a part, parts can be rejected by 10-20% of their nominal value. The field-effect transistor can be replaced with any similar or more powerful one that I advise you. You adjust the loop capacitor yourself, it is optimal 0.5-1 μF more and is not needed for the pulse mode.
Coils.
The primary winding of the qualifier is made with a wire of 2 squares, the number of turns is from 4 to 10. The secondary winding is wound with high-quality PLSHO 0.25 mm or any other, the number of turns is from 500 to 1000 (there is no more sense), I advise you to cover everything with varnish or epoxy at the end of the winding.
The L1 choke has a resistance of 15-40 ohms, it is located in the LDS lamps, it can be replaced with a resistor with the same resistance and a power of at least 100 watts.
Kacher's photo
Ready for use.
Control unit with power button.
Electronics.
List of radioelements
| Designation | A type | Denomination | amount | Note | Score | My notebook |
|---|---|---|---|---|---|---|
| IC1, IC2 | Programmable timer and oscillator | NE555 | 2 | Into notepad | ||
| T1, T2 | MOSFET transistor | IRFP460 | 2 | Into notepad | ||
| D1, D2 | Suppressor | 1.5KE12 | 2 | Into notepad | ||
| Br1 | Diode bridge | 15A 500V | 1 | Into notepad | ||
| Br2 | Diode bridge | 1A 50V | 1 | Into notepad | ||
| C1 | 1000 uF 16V | 1 | Into notepad | |||
| C2 | Capacitor | 0.6 uF | 1 | Into notepad | ||
| C2, C7 | Electrolytic capacitor | 5 uF | 2 | Into notepad | ||
| C3, C4 | Capacitor | 100 nF | 2 | Into notepad | ||
| R1, R2 | Variable resistor | 50 kΩ | 2 | Into notepad | ||
| R3, R4 | Resistor | 1 kΩ | 2 | Into notepad | ||
| R5 | Resistor | 100 ohm | 1 | Into notepad | ||
| R6 | Resistor | 50 kΩ | 1 |
High voltage entertainment is a lot of fun and little benefit. This means we definitely need to collect something like that. Probably the simplest power supply circuit for a Tesla coil is Brovin's caster. It can be assembled on a lamp, on a conventional or field-effect transistor. The scheme is unpretentious - it works without configuration.
Many legends circulate around Kecher Brovin because of the non-standard connection diagram of the transistor, which works in extreme modes - it breaks down inside itself and immediately recovers. We will not describe the dry theory, we only need the result.
I will give two diagrams for connecting the kacher.
For NPN transistor:
For a field-effect transistor:
It was decided to assemble the second circuit on a field-effect transistor since there were no other powerful transistors at hand.
My circuit consisted of: resistor R2 - 2 kOhm, resistor R1 - 10 kOhm, field-effect transistor VT1 - IRLB8721 (it was fixed on a powerful radiator because it gets very hot). The circuit was powered by 12 volts.
The secondary coil was wound on a sewer pipe with a thin wire. Approximately 800 turns. I clamped the pipe into a screwdriver and wound it as much as it would fit.
The primary winding was made 1.5 turns thick copper wire... It is better to make the winding diameter larger than the secondary. It is better to select the position and number of turns empirically in order to select the maximum voltage output.
An increase in the discharge power can be achieved not only by tuning the antenna, selecting resistors, but also by connecting a powerful choke with a large capacitor to the power input. Increasing the supply voltage proportionally increases the length of the discharges.
Kecher turned out not super powerful, but enough for pampering. It knocked out up to 7 mm in the air. I confidently lit gas-discharge lamps 20 cm from the winding, gave beautiful corona discharges in incandescent lamps.
It was decided to test the first circuit on the KT805AM transistor with the same resistor ratings as for the field one (2 kOhm and 10 kOhm). Surprisingly, the power of the discharges doubled, and the corona discharge burned steadily in the air. Since it was so flooded, I designed the installation in the form of a finished device.
In this review, we present to your attention a diagram of the assembly of a Brovin or Tesla transformer.
We need:
- winding wire;
- NPN transistor;
- 47 kOhm resistor;
- Light-emitting diode;
- plastic or polypropylene pipe 140 mm long and 22 mm in diameter;
The winding wire does not need to be purchased as it is present in every charger or power supply unit. If you decide to remove the wire from the power supply, then we note that it is wrapped around a "W" or "E" shaped transformer. One of the coils on the transformer has a thick, rather short wire. The wire on the second coil is much thinner and much larger. In any case, the transformer must be disassembled to get to the wire. This can be done by knocking on the body with a hammer, due to which the varnish will gradually break and the transformer will fall apart.
Next, you need to remove the layer of electrical tape on the wires and release the winding wire.
Let's start with the coil. First you need to find the length of the wire of one turn. To do this, multiply the number Pi (3.14) by the outer diameter of the pipe. If you use a pipe with a diameter of 22 mm, you get 6.9 cm.
Now we take the length of the turn and multiply it by the required number of turns. In the case of the author, there will be 450 of them. As a result, it turns out that we need 31 m of wire to make a coil of 450 turns on the pipe, which the author uses.
Next, on the desktop, we measure the distance of one meter. This is necessary to accurately mark the wire.
We wrap the coil. This can be done manually, but you can also build a simple unit from a screwdriver or drill and make the winding easier.
Next, we take a 47 kΩ resistor, one LED, a coil and an NPN transistor. The author does not advise using small transistors, since they cannot withstand high voltages and loads. The best of all the transistors that the author used was the BD241 transistor.
Let's start the very assembly of the circuit, which the author makes on the BreadBoard for greater clarity.
The diagram shows that the plus goes through the resistor and goes to the transistor, but also goes to the coil, from where it also goes to the transistor. Therefore, the first thing we do is connect the transistor.
The pinout of the transistor is simple. We represent it in the figure below, where B means basic, C is a collector
We connect the resistor to the base leg.
The second plus should go to the coil, which in this case is a simple wire with five turns around the wire that was wound in the beginning. We connect one end of the wire to the collector. We connect the other end of the wire to one contact from the coil.
We connect the second contact from the coil directly to the plus.
Kacher differs from the blocking generator by the electron plasma generated in the p-n-junction, due to which we obtain a sufficiently high output voltage without using a high-voltage transformer. This can be seen if you collect the simple diagram below. The only transformer in it is two windings on ferrite rings for 20 and 5 turns. Despite its simplicity, with 12V power supply, the circuit gives at the output X1 about 1700 Volts of impulse voltage (no load).
The circuit can operate in two modes: economical (open switch SA1) and normal (contact SA1 closed). In economical mode, at 12V power supply, the device consumes a current of 200..300mA.
The most interesting detail in the circuit is the TV1 ferrite transformer. It is wound on two 10mm diameter ferrite beads folded together. 
The collector winding is 5 turns, and the base winding is 20, moreover, if the first one winds clockwise, then the second turns counterclockwise. It is desirable to use the wire in fluoroplastic insulation, with a diameter of 0.05-0.3mm. It is better to wind the collector winding with a thicker wire.
Different transistors have been tested for this circuit. The regularity was found out as follows: the higher the rated maximum collector-emitter voltage, and the steeper the I - V characteristic of the transistor, the higher the voltage can be obtained at the output. The pulse high voltage MJE13005 was ideal. It will need to be installed on a small radiator.
Chokes L1 and L2 are standard, for 100μH. Choose capacitors for a voltage of at least 100V.
Customization
Here you need an oscilloscope with a high-impedance output, the probe of which must be located near the output of X1. Better not to connect directly, because high voltage can damage the oscilloscope. Set R1 to the middle position, open the SA1 switch, and connect the 12V power supply. If the oscilloscope does not show any pulse pulses, then change the terminals of the TV1 base winding.
If there is no oscilloscope, then the device can be configured using the "Avramenko plug". It needs to be connected with one single input to the output of the kahara.
When the card is running, the HL1 LED will glow despite the fact that the other end of this simple device is not connected anywhere.
Depending on the tasks to be solved, it may be necessary to connect the crawler to different loads. The simplest thing is to power a 220V fluorescent lamp through a diode (preferably SF56) and a smoothing capacitor. With SA1 closed and 15V supply voltage, you can light a 10-watt bulb.
Some tasks require fast charging of the capacitor to high voltages. This can be done according to the previous scheme, but the capacitor should be. non-electrolytic and rated for a voltage of 2000V. Also, in this case, instead of one, you need to put 4 diodes connected in series.
The most interesting connection is a long line, usually a coaxial cable. Its braid is connected to the common wire of the circuit, and the central core is connected to the X1 output.
And what will happen if instead of one transistor you put two in the kahar circuit and make them work alternately? Read about it.
Materials used
- Korotkov D.A. Development and research of powerful generators nanosecond pulses based on drift sharp recovery diodes and deep level dinisters
- Pichugina M.T. Powerful impulse energy
Gorchilin Vyacheslav, 2014
* Reprinting of the article is possible subject to the installation of a link to this site and the observance of copyright