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How to assemble a high-voltage generator with low current. High voltage generator. HV generator testing

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My generator high voltage (H.V.) I use in many of my projects ( , ):

Elements -
1 - switch
2 - varistor
3 - E/m interference suppression capacitor
4 - step-down transformer from the UPS
5 - rectifier (Schottky diodes) on the radiator
6 - smoothing filter capacitors
7 - voltage stabilizer 10 V
8 - rectangular pulse generator with duty cycle adjustable by variable resistor

10 - IRF540 MOSFETs connected in parallel, mounted on a radiator
11 - high-voltage coil on a ferrite core from a monitor
12 - high voltage output
13 - electric arc

The source circuit is quite standard, based on the flyback converter circuit ( flyback converter):

Input circuits

Varistor serves for overvoltage protection:

S- disk varistor
10 - disc diameter 10 mm
K- error 10%
275 - max. AC voltage 275 V

Capacitor C reduces interference generated by the generator in the power supply network. It is used as an interference suppression capacitor X type.

Constant voltage source

Transformer - from an uninterruptible power supply:

Transformer primary winding Tr connected to mains voltage 220 V, and the secondary to a bridge rectifier VD1.

The effective voltage value at the output of the secondary winding is 16 V.

The rectifier is assembled from three cases of dual Schottky diodes mounted on a radiator - SBL2040CT, SBL1040CT:

SBL 2040 C.T.- max. average rectified current 20 A, max. peak reverse voltage 40 V, max. effective reverse voltage 28 V
connected in parallel:
SBL 1040 C.T.- max. average rectified current 10 A, max. peak reverse voltage 40 V, max. effective reverse voltage 28 V
SBL 1640 - max. average rectified current 16 A, max. peak reverse voltage 40 V, max. effective reverse voltage 28 V

The pulsating voltage at the rectifier output is smoothed out by filter capacitors: electrolytic CapXon C1, C2 with a capacity of 10,000 µF at a voltage of 50 V and ceramic C3 with a capacity of 150 nF. Then a constant voltage (20.5 V) is supplied to the key and to a voltage stabilizer, the output of which is a voltage of 10 V, which serves to power the pulse generator.

Voltage stabilizer assembled on a microcircuit IL317:

Throttle L and capacitor C serve to smooth out voltage ripples.
Light-emitting diode VD3 connected through a ballast resistor R4, serves to indicate the presence of voltage at the output.
Variable resistor R2 serves to adjust the output voltage level (10 V).

Pulse generator

The generator is assembled on a timer NE555 and produces rectangular pulses. A special feature of this generator is the ability to change the duty cycle of pulses using variable resistor R3, without changing their frequencies. From the duty cycle of the pulses, i.e. The voltage level on the secondary winding of the transformer depends on the ratio between the duration of the switch on and off states.

Ra = R1+ top part R3
Rb= bottom part R3 + R2
duration "1" $T1 = 0.67 \cdot Ra \cdot C$
duration "0" $T2 = 0.67 \cdot Rb \cdot C$
period $T = T1 + T2$
frequency $f = (1.49 \over ((Ra + Rb)) \cdot C)$

When moving the variable resistor slider R3 total resistance Ra + Rb = R1 + R2 + R3 does not change, therefore the pulse repetition rate does not change, but only the ratio between Ra And Rb, and, consequently, the duty cycle of the pulses changes.

Key and
Pulses from the generator are controlled through the driver by a key on two connected in parallel -ah ( - metal-oxide-semiconductor field effect transistor, MOS transistor ("metal-oxide-semiconductor"), MOS transistor ("metal-insulator-semiconductor"), field-effect transistor with insulated gate) IRF540N in the case TO-220, mounted on a massive radiator:

G- shutter
D- stock
S- source
For transistor IRF540N The maximum drain-to-source voltage is VDS = 100 volts, and the maximum drain current I D = 33/110 amps. This transistor has low on-resistance RDS(on) = 44 milliohms. The transistor opening voltage is V GS(th) = 4 volts. Operating temperature - up to 175° C .
Transistors can also be used IRFP250N in the case TO-247.

The driver is needed for more reliable control -transistors. In the simplest case, it can be assembled from two transistors ( n-p-n And p-n-p):

Resistor R1 limits gate current when turned on -ah, and a diode VD1 creates a path for the gate capacitance to discharge when turned off.

Closes/opens the circuit of the primary winding of a high-voltage transformer, which is used as a horizontal scan transformer (“linear scan”, flyback transformer (FBT)) from an old monitor Samsung SyncMaster 3Ne:

The circuit diagram of the monitor shows the high voltage output H.V. line transformer T402 (FCO-14AG-42), connected to the anode of the kinescope CRT1:

From the transformer, I only used the core, since the line transformer has built-in diodes that are filled with resin and cannot be removed.
The core of such a transformer is made of ferrite and consists of two halves:

To prevent saturation in the core using a plastic spacer ( spacer) an air gap is created.
I wound the secondary winding with a large number (~ 500) turns of thin wire (resistance ~ 34 Ohms), and the primary winding with a thick wire with a small number of turns.

Sudden changes in current in the primary winding of the transformer when turned off -a induce high-voltage pulses in the secondary winding. This consumes the magnetic field energy accumulated as the current in the primary winding increases. The secondary winding leads can either be connected to electrodes to produce an electric arc, for example, or connected to a rectifier to produce a high DC voltage.

Diode VD1 and resistor R(snubber (snubber) chain) limit the self-induction voltage pulse on the primary winding of the transformer when the switch is opened.

High Voltage Generator Simulation
Results of modeling processes in a high voltage generator in the program LTspice are presented below:

The first graph shows how the current in the primary winding increases according to the exponential law (1-2), then abruptly stops at the moment the switch opens (2).
The voltage on the secondary winding reacts slightly to the smooth increase in current in the primary winding (1), but increases sharply when the current is interrupted (2). During the interval (2-3), there is no current in the primary winding (the key is turned off), and then it begins to increase again (3).

Powerful high voltage generator (Kirlian apparatus), 220/40000 volts

The generator produces voltages up to 40,000 V and even higher, which can be applied to the electrodes described in previous projects.

It may be necessary to use a thicker glass or plastic plate in the electrode to avoid serious electrical shock. Although the circuit is powerful, its output current is low, reducing the risk of fatal shock if it comes into contact with any parts of the device.

However, you should be extremely careful when handling it, as the possibility of electric shock cannot be ruled out.

Attention! High voltages are dangerous. Be extremely careful when working with this circuit. It is advisable to have experience with such devices.

You can use the generator in experiments with Kirlian photography (electrophotography) and other paranormal experiments, such as those involving plasma or ionization.

The circuit uses conventional components and has an output power of about 20 W.

Below are some characteristics of the device:

power supply voltage - 117 V or 220/240 V (AC mains);
output voltage - up to 40 kV (depending on the high-voltage transformer);
output power - from 5 to 25 W (depending on the components used);
number of transistors - 1;
operating frequency - from 2 to 15 kHz.

Principle of operation

The diagram shown in Fig. 2.63, consists of a single-transistor generator, the operating frequency of which is determined by capacitors C3 and C4 and the inductance of the primary winding of the high-voltage transformer.

Rice. 2.63 Kirlian apparatus

The project uses a high-power silicon npn transistor. To remove heat, it should be mounted on a sufficiently large radiator.

Resistors R1 and R2 determine output power, setting the transistor current. Its operating point is set by resistor R3. Depending on the characteristics of the transistor, it is necessary to experimentally select the value of resistor R3 (it should be in the range of 270...470 Ohms).

The horizontal output transformer of the TV (horizontal transformer) with a ferrite core is used as a high-voltage transformer, which also determines the operating frequency. The primary winding consists of 20...40 turns of ordinary insulated wire. A very high voltage is generated on the secondary winding, which you will use in experiments.

The power supply is very simple; it is a full-wave rectifier with a step-down transformer. It is recommended to use a transformer with secondary windings providing voltages of 20...25 V and currents of 3...5 A.

Assembly

The list of elements is given in table. 2.13. Since the assembly requirements are not very strict, in Fig. Figure 2.64 shows the installation method using a mounting block. It contains small parts, such as resistors and capacitors, interconnected by hinged mounting.

Table 2.13. List of elements

Large parts, such as a transformer, are screwed directly to the housing.

It is better to make the body plastic or wooden.

Rice. 2.64. Device installation

The high-voltage transformer can be removed from a non-working black-and-white or color TV. If possible, use a TV with a diagonal of 21 inches or larger: the larger the kinescope, the greater the voltage the TV’s line transformer should generate.

Resistors R1 and R2 - wirewound C1 - any capacitor with a nominal value of 1500...4700 µF.

HV blocking generator (high voltage power supply) for experiments - you can buy it on the Internet or make it yourself. To do this, we need not very many parts and the ability to work with a soldering iron.

In order to assemble it you need:

1. Line scan transformer TVS-110L, TVS-110PTs15 from tube b/w and color TVs (any line scanner)

2. 1 or 2 capacitors 16-50V - 2000-2200pF

3. 2 resistors 27 Ohm and 270-240 Ohm

4. 1-Transistor 2T808A KT808 KT808A or similar characteristics. + good radiator for cooling

5. Wires

6. Soldering iron

7. Straight arms

And so we take the liner, disassemble it carefully, leave the secondary high-voltage winding, consisting of many turns of thin wire, a ferrite core. We wind our windings with enameled copper wire on the second free side of the ferite core, having previously made a tube around the ferite from thick cardboard.

First: 5 turns approximately 1.5-1.7 mm in diameter

Second: 3 turns approximately 1.1mm in diameter

In general, the thickness and number of turns can vary. I made what was at hand.

In the closet they found resistors and a pair of powerful bipolar n-p-n transistors- KT808a and 2t808a. He did not want to make a radiator - due to the large size of the transistor, although later experience showed that a large radiator is definitely needed.

To power all this, I chose a 12V transformer; it can also be powered from a regular 12 volt 7A battery. from a UPS (to increase the output voltage, you can supply not 12 volts but, for example, 40 volts, but here you already need to think about good cooling of the trance, and the turns of the primary winding can be made not 5-3 but 7-5 for example).

If you are going to use a transformer, you will need a diode bridge to rectify the current from AC to DC, the diode bridge can be found in the power supply from the computer, you can also find capacitors and resistors + wires there.

As a result, we get 9-10 kV output.

I placed the entire structure in the PSU housing. It turned out to be quite compact.

So, we have an HV Blocking generator which gives us the opportunity to carry out experiments and run the Tesla Transformer.

Before we move on to the description of the high voltage source proposed for assembly, let us remind you of the need to observe general safety precautions when working with high voltages. Although this device produces an extremely low current output, it can be dangerous and will cause a rather unpleasant and painful shock if accidentally touched in the wrong place. From a safety point of view, this is one of the safest high-voltage sources, since the output current is comparable to that of conventional stun guns. High voltage at output terminals - direct current about 10-20 kilovolts, and if you connect a spark gap, you can get an arc of 15 mm.

High voltage source circuit

The voltage can be adjusted by changing the number of stages in the multiplier, for example if you want it to light neon lights you can use one, if you want spark plugs to work you can use two or three, and if you want a higher voltage you can use 4. 5 or more. Fewer stages means less voltage but more current, which can make the device more dangerous. Paradoxically, the higher the voltage, the less difficult it will be to cause power-related damage as the current drops to negligible levels.

How it works

After pressing the button, the IR diode turns on and the light beam hits the optocoupler sensor, this sensor has an output resistance of about 50 ohms, which is enough to turn on the 2n2222 transistor. This transistor supplies battery energy to power the 555 timer. The frequency and duty cycle of the pulses can be adjusted by changing the ratings of the trim components. In this case, the frequency can be adjusted using a potentiometer. These oscillations, through the BD679 transistor, which amplifies the current pulses, enter the primary coil. An alternating voltage increased by 1000 times is removed from the secondary and rectified by an explosive multiplier.

Parts for assembling the circuit

The microcircuit is any timer of the KR1006VI1 series. For the coil - a transformer with a winding resistance ratio of 8 Ohm: 1 kOhm. The first thing to consider when choosing a transformer is size, as the amount of power they can handle is proportional to their size. For example, the size of a large coin will give us more energy than a small transformer.

The first thing you need to do to rewind it is to remove the ferrite core to access the coil itself. In most transformers, the two parts are glued together, just hold the transformer with pliers over a lighter, just be careful not to melt the plastic. After a minute, the glue should melt and you need to break it into two parts of the core.

Keep in mind that ferrite is very brittle and cracks quite easily. To wind the secondary coil, 0.15 mm enameled copper wire was used. Winding until almost full, so that later there is enough for another layer of thicker wire 0.3 mm - this will be the primary. It should have several dozen turns, about 100.

Why is an optocoupler installed here - it will provide complete galvanic isolation from the circuit; there will be no electrical contact with it between the power supply button, the microcircuit and the high-voltage part. If a high power supply voltage accidentally breaks through, you will be safe.

It is very easy to make an optocoupler; insert any IR LED and IR sensor into a heat-shrinkable tube, as shown in the picture. As a last resort, if you don’t want to complicate matters, remove all these elements and supply power by closing K-E transistor 2N2222.

Note the two switches in the circuit, this is done because each hand must be used to activate the generator - this will be safe and reduces the risk of accidental activation. Also, when operating the device, you should not touch anything other than the buttons.

When assembling the voltage multiplier, be sure to leave enough clearance between the elements. Trim any protruding leads as they can cause corona discharges which greatly reduce efficiency.

We recommend insulating all exposed contacts of the multiplier with hot melt adhesive or other similar insulating material and then wrapping them in heat shrink tubing or electrical tape. This will not only reduce the risk of accidental impacts, but will also improve the efficiency of the circuit by reducing losses through air. Also, for insurance, they added a piece of foam between the multiplier and the generator.

The current consumption should be approximately 0.5-1 ampere. If more, it means the circuit is poorly configured.

HV generator testing

Two different transformers were tested - both with excellent results. The first had a smaller ferrite core and therefore less inductance, operated at a frequency of 2 kHz, and the other about 1 kHz.

When starting for the first time, first check the NE555 generator to see if it is working. Connect a small speaker to leg 3 - you should hear sound coming from it as the frequency changes. If everything gets very hot, you can increase the resistance of the primary winding by winding it with a thinner wire. And a small heatsink for the transistor is recommended. And the correct tuning frequency is important to avoid this problem.

Everyone knows that in the original the Tesla resonant transformer was made on a lamp, but with the development of electronics it became possible to significantly reduce and simplify the dimensions of this device, if instead of a lamp you use a conventional bipolar transistor of the KT819 type or another similar in current and power. Of course with field effect transistor the results will be even better, but this circuit is designed for those who are taking their first steps in assembling high-voltage generators. Schematic diagram device is shown in the figure:

The communication and collector coils are wound with 0.5-0.8 mm wire. For a high-voltage coil we take any wire with a thickness of 0.15-0.3 mm and approximately 1000 turns. At the “hot” end of the high-voltage winding we place such a spiral - everything is like in a real Tesla. In my version, I took power from a 10V 1A transformer.

Of course, with a power supply of 24V and higher, the length of the corona discharge will increase significantly. After the secondary winding there is a rectifier and a 1000uF 25V capacitor. The transistor for the generator was used KT805IM. for the diagram in the archive.