Linear transformer tvs. Singing arc (ionophone)

Table 5.15 shows the maximum possible during the campaign values ​​of the coefficients of non-uniformity of energy release and power of fuel assemblies for typical cells of the reactor core. The values ​​of the coefficients of non-uniformity of energy releases are taken according to the data of Section 5.3.6, obtained by simulating successive loads in each of these cells of fresh fuel assemblies on the physical model of the reactor with an average burnup over the core of about 20%.

Table No. 5.15

Maximum possible power characteristics of fuel assemblies in typical core cells during the campaign

Figures in brackets of the first line of table. 5.15 correspond to the number of full-scale fuel assemblies (per 188 fuel elements), rounded to the nearest integer, located in the energy-releasing space of the core at the time of its state, corresponding to the maximum values ​​of the coefficients of non-uniformity of energy releases for a typical cell. This number is determined by the position of the KO (the fraction of the fuel suspension introduced into the zone) and the number of fuel assemblies 184.05 (160 fuel elements) located in the core (for the data given in Table 5.15, it is assumed to be 6).

Calculations of the maximum values ​​of the temperature parameters of fuel elements, which can be realized during the campaign in typical cells of the core, for a stationary mode of operation of the reactor at a nominal power level of 100 MW were carried out using the KANAL-K program. In each fuel assembly according to table. No. 5.15, a fragment of 8 neighboring most stressed fuel elements was calculated, including the fuel element with the maximum energy release. The initial data and calculation results are summarized in table. No. 5.16.

Table No. 5.16

Design parameters of fuel assemblies and fuel rods at a reactor power of 100 MW

Parameter	Meaning
Reactor power, MW
Coolant temperature at the core inlet, о С
Coolant pressure at the reactor inlet, MPa
Coolant temperature in the lower mixing chamber, о С	88,5
Typical cell number
Coolant flow through fuel assemblies, m 3 / h	40,2	49,9	37,8	65,7	121,8
Average speed of the coolant, m / s	3,9	4,9	3,7	6,6	12,0
Coolant temperature at the outlet of the computational cell with the maximum energy release, о С
Maximum temperature of the fuel element cladding in the valley of the cross, о С	300,1	301,1	298,1	304,7	313,5
Maximum temperature of the fuel composition in the center of the cross, о С	416,2	428,1	398,3	463,6	575,0
7,0	8,4	6,3	10,8	17,6
Maximum design safety factor for critical thermal loads, Ккр	1,51	1,51	1,51	1,51	1,51

As a consequence of the partial overload mode used at the SM-3 reactor, the distribution of energy release over the core changes both from campaign to campaign and in the course of each individual campaign. During overloads, fresh fuel assemblies are installed, as a rule, by two in the inner and outer layers of the zone and no more than two fuel assemblies in a quadrant. In the course of the campaign, the distribution of energy release depends on the movement of the control rotor control system, changes in the volume of the zone due to the introduction of additional fuel loads of the control system, which are uneven over the burnout and poisoning zone. With this in mind, the implementation of those given in table. No. 5.16 of cooling modes of fuel elements in a particular set of fuel cells will also depend on a specific campaign and its course.

A feature of the operation of fuel elements in the SM-3 reactor, as well as in SM-2, is the use of forced cooling of the most energetically stressed fuel elements due to the assumption of surface boiling of the coolant in all typical cells of the zone in modes with maximum energy release in the fuel assemblies of these cells (hydroprofiling with the provision of the same reserve up to crisis). On the part of the fuel elements with the maximum energy release, the temperature of the outer surface of the cladding of the fuel elements is higher than the saturation temperature, which causes the formation of bubbles in the microdepressions of its surface. In turn, the subcooling of the coolant to the saturation temperature leads to rapid condensation of vapor bubbles, and, thus, the volumetric vapor content in the flow is absent. The boiling of the coolant increases the heat transfer coefficient, which leads to the preservation of the temperature of the cladding of the fuel elements at a relatively low level. During the entire operation period of the SM-2 and SM-3 reactors, no hydraulic and neutron instabilities were observed in the operation of the core and CPS.

Attention! The multiplier gives a very large CONSTANT voltage! This is really dangerous, so if you decide to repeat it, be extremely careful and follow safety precautions. After the experiments, the output of the multiplier must be discharged! The installation can easily kill equipment, take digital pictures only from afar, and carry out experiments far from the computer and other household appliances.

This device is the logical conclusion of the topic on the use of the TVS-110LA line transformer, and a generalization of the article and forum topic.

The resulting device has found application in various experiments where high voltage is required. The final diagram of the device is shown in Fig. 1.

The circuit is very simple, and it is a common blocking generator. Without a high-voltage coil and a multiplier, it can be used where an alternating high voltage with a frequency of tens of Hz is needed, for example, it can be used to power an LDS or to test similar lamps. A higher AC voltage is obtained using a high voltage winding. To obtain a high constant voltage, a UN9-27 multiplier was used.

Fig. 1 Schematic diagram.

Photo 1. External view of the power source on TVS-110

Photo 2. External view of the power source on TVS-110

Photo 3. External view of the power source on TVS-110

Photo 4. External view of the power source on TVS-110

Now very often you can find outdated CRT TVs in the garbage, with the development of technology they are not relevant, so now they are basically getting rid of. Perhaps everyone has seen an inscription in the spirit of “High voltage. Don `t open". And it hangs there for a reason, because in every TV set with a picture tube there is a very amusing thing called TDKS. The abbreviation stands for "diode-stage lowercase transformer", in the TV it serves, first of all, to generate a high voltage to power the kinescope. At the output of such a transformer, a constant voltage of as much as 15-20 kV can be obtained. The alternating voltage from the high-voltage coil in such a transformer is increased and rectified using a built-in diode-capacitor multiplier.
TDKS transformers look like this:

The thick red wire extending from the top of the transformer, as you might guess, is designed to remove high voltage from it. In order to start such a transformer, you need to wind your primary winding on it and assemble a simple circuit called the ZVS driver.

Scheme

The diagram is presented below:

The same diagram in a different graphical representation:

A few words about the scheme. Its key link is the IRF250 field-effect transistors; IRF260 is also well suited here. Instead of them, you can put other similar field-effect transistors, but these are the ones that have proven themselves best in this circuit. Zener diodes for a voltage of 12-18 volts are installed between the gate of each of the transistors and the minus of the circuit, I put the zener diodes BZV85-C15, for 15 volts. Also, ultrafast diodes, for example, UF4007 or HER108, are connected to each of the gates. A 0.68 μF capacitor is connected between the drains of the transistors for a voltage of at least 250 volts. Its capacity is not so critical, you can safely put capacitors in the range of 0.5-1 μF. Quite significant currents flow through this capacitor, so it can be heated. It is advisable to put several capacitors in parallel, or take a capacitor for a higher voltage, 400-600 volts. There is a choke on the diagram, the rating of which is also not very critical and can be in the range of 47 - 200 μH. You can wind 30-40 turns of wire on a ferrite ring, it will work anyway.

Manufacturing

If the choke gets very hot, then you should reduce the number of turns, or take a wire with a thicker section. The main advantage of the circuit is its high efficiency, because the transistors in it almost do not heat up, but, nevertheless, they should be installed on a small radiator, for reliability. When installing both transistors on a common radiator, it is imperative to use a heat-conducting insulating gasket, because the metal back of the transistor is connected to its drain. The supply voltage of the circuit lies in the range of 12 - 36 volts, at a voltage of 12 volts at idle, the circuit consumes about 300 mA, with a burning arc the current rises to 3-4 amperes. The higher the supply voltage, the higher the voltage will be at the output of the transformer.
If you look closely at the transformer, you can see the gap between its case and the ferrite core of about 2-5 mm. On the core itself, you need to wind 10-12 turns of wire, preferably copper. You can wind the wire in any direction. The larger the cross-section of the wire, the better, however, a wire of too large a cross-section may not fit into the gap. You can also use enamelled copper wire, it will crawl through even the tightest gap. Then you need to tap from the middle of this winding, exposing the wires in the right place, as shown in the photo:

You can wind two windings of 5-6 turns in one direction and connect them, in this case, a branch from the middle is also obtained.
When the circuit is turned on, an electric arc will occur between the high-voltage terminal of the transformer (thick red wire at the top) and its minus. Minus is one of the legs. Determining the required minus leg can be quite simple if you bring "+" to each leg in turn. Air breaks through at a distance of 1 - 2.5 cm, so a plasma arc will immediately appear between the desired leg and the plus.
You can use such a high-voltage transformer to create another interesting device - Jacob's ladder. It is enough to place two straight electrodes with the letter "V", connect a plus to one, and a minus to the other. The discharge will appear at the bottom, begin to creep upward, break at the top, and the cycle will repeat itself.
You can download the board here:

(Downloads: 581)

Due to the high power consumption, the horizontal output stage operates in a severe temperature regime, and therefore most of the failures of TVs are associated with it.

Usually, the biggest problems arise when a split transformer fails. An example is a malfunction in the LOEWE CLASSIC TV on the C8001 STEREO / 85 chassis.

In the process of troubleshooting, it was found that the output transistor T539 of the BU508A type (split transformer 2761419) was broken.

Unfortunately, it was not possible to find the original transformer, so I had to solve the problem in a different way.

A fragment of the line scan output stage of this TV is shown in Fig. 1. The voltage of the secondary windings of the split transformer, as well as their polarity, most European firms indicate on the printed circuit board, directly at the output. In the absence of this information, you can proceed as follows. As a rule, the overwhelming number of transformer failures is recorded in their high-voltage part, while the secondary windings are in working order. Therefore, having found among them the filament winding of the kinescope (6.3 V), you can apply the filament voltage to it from a working TV (for example, with pin 7-8 of TVS110-PC15 of the 3USCT TV), having previously disconnected it from the contacts of the kinescope panel. The polarity of the pulses of the secondary windings is determined based on the polarity of the rectifier diode connected to this winding.

In our case, the winding 9-10 of the transformer is the power winding of the video amplifiers. But this method of determining the polarity and voltage of the secondary windings is extremely rare, since the reference literature contains almost all split-transformer circuits indicating the voltages of the primary and secondary windings, as well as their polarity.

In our particular case, it was found that the voltages of the secondary windings of the transformer are designed to power the following functional units:

9-1 - 60 V - to form the tuner tuning voltage;

9-10 - 200 V - for power supply of video amplifiers;

9-5 - 6.3 - to power the heating of the kinescope;

9-8 - 12 V - for powering the radio channel and color channel microcircuits;

9-6 - 27 V - to power the vertical scan.

It should be noted that voltages of 12 and 27 V are obtained by rectifying not the negative part of the horizontal pulse, but its positive component, which should be paid special attention to in the absence of documentation for the transformer. The reference point here can be the video amplifier power winding (9-10), the voltage of which (usually 180 ... 220 V) is obtained by rectifying horizontal pulses of positive polarity.

Having dealt with the secondary windings, let's start manufacturing a unit designed to replace a faulty split transformer. The design is based on the unit of the line scan output stage of the 3USCT TV, the diagram of which is shown in Fig. 2. The winding data of the transformer windings are given in the table.

Winding	Power, W	Wire type	Number of turns

The purpose of the secondary windings of the transformer is as follows:

7-8 - power winding of the tube heating;

4-5, 4-3, 4-6, 4-2 - power windings of the raster correction submodule and the information block;

14-15 - high voltage winding.

Based on the foregoing, it is obvious that the secondary windings 4-5, 4-6 of TVS 110-PTs16 can be used instead of windings 9-1, 9-10 of a split transformer, winding 4-2 - instead of winding 9-6, winding 7-8 - instead of winding 9-5. As for obtaining a voltage of negative polarity of 150 V, then here you will have to wind the winding 4-3 to a power of 10 W. When using the TVS 110-PC15 transformer, you will have to additionally wind the windings 3-2, 5-6 that are missing in it. It is convenient to wind additional windings on the free side of the fuel assembly core with MGTF-0.3-0.5 or PEV-2-0.4 wire. In the latter case, insulating spacers are required between the core and the winding.

When winding, it is necessary to pay attention to the inphase of the additional windings. The high-voltage unit in the basic circuit solutions repeats a similar unit of the 3USCT TV. The difference lies only in the methods of supplying the accelerating voltage and signal to the kinescope for devices for stabilizing the image size in lines and limiting the beam current.

The resistors for adjusting the focusing and accelerating voltages are used from a broken split transformer and glued with heat-resistant glue to the housing of the UN9 / 27-1.3 A multiplier.

If these resistors cannot be removed without damaging them from the case of the split transformer, then the circuit for supplying these voltages to the kinescope should be implemented in the same way as that used in 3USTST TVs.

The redesigned line scan output stage of the aforementioned LOEWE TV is shown in Fig. 3.

TVS 110-PC16 is installed in place of the soldered split transformer at a distance of 1 cm from the surface of the printed circuit board, and its leads are unsoldered according to the above diagram. If there are no installation errors, the output stage, as a rule, starts working immediately, a raster appears on the screen. Having fed the signal of the color stripes to the TV input, the focusing and accelerating voltages are adjusted, then the horizontal and vertical dimensions of the raster are estimated.

Due to the fact that the parameters of the winding 9-12 of TVS 110-PC16 are not completely identical to the parameters of the winding 2-4 of the split transformer, there may be an increased or decreased horizontal raster size. If the variable resistor R586 (horizontal size) cannot be set to a normal size raster, then you will need to select the capacitance of the capacitor C540, having previously set R586 to the middle position. The vertical size adjustment is usually within the value of the variable resistor R564.

Then it is necessary to check the secondary voltages of the windings of the TVS 110-PC16 transformer. In this TV, the voltage value after the rectifiers on the filter capacitors is indicated on the printed circuit board, therefore measurements are made with a DC voltmeter. If there is only the amplitude of the pulses on the secondary windings, it is measured with an oscilloscope. As practice has shown, the amplitude of the pulses of the secondary windings can differ from the nominal within ± 10%, which does not adversely affect the operation of the TV. If the amplitude differs by more than 10%, it is necessary to carefully examine the shape of the horizontal pulse for the absence of surges and excitation at a high frequency. To do this, the oscilloscope is connected to any secondary winding of the TVS 110-PC16, and the adjustment is made by selecting the capacitances of the capacitors C547, C546, C583, C540. In the event that the amplitude of the pulses of the secondary windings exceeds the rating by more than 10%, it is necessary to reduce the number of turns L add. to match the rating, and as for the windings 4-5, 4-6, 4-2, then there is a ballast resistor in the circuit of these windings (for example, R506 in the +200 V circuit). By increasing the value of this resistor, the rectified voltage approaches the nominal value.

The next step is to adjust the heating voltage of the kinescope. Due to the high identity of the parameters of the split transformers and the filaments of the kinescopes, this TV does not have a system for regulating the filament voltage, and an unregulated choke L541 is connected in series with the filament winding. The voltage value is controlled by the oscilloscope directly on the contacts of the kinescope panel. To carry out the adjustment, in series with the choke L541, a resistor R d of type C5-37 is installed, the selection of the resistance of which (within 1 ... 3 ohms) sets the nominal voltage. Good results are obtained by installing an adjustable choke L5 instead of L541 (for example, from the KR-401 module of the Gorizont plant). If the filament voltage is less than the nominal, 1-2 turns are additionally wound in series with the winding 7-8 TVS110-PC16 and the re-adjustment is made. The UN9 / 27-1.3 A multiplier is installed in any convenient place on the TV case and connected to the pin. 15 fuel assemblies with a high-voltage wire.

As practice has shown, the power of the TVS 110-PC16 transformer is quite sufficient for the operation of the output stages of televisions with a screen size of 67 ... 70 cm. split transformer. In a similar way, several television sets produced in the mid-80s were repaired, after which they showed high reliability and stability in operation.

Low-power high-voltage generators are widely used in flaw detection, to power portable charged particle accelerators, X-ray and cathode-ray tubes, photomultiplier tubes, and ionizing radiation detectors. In addition, they are also used for electric pulse destruction of solids, obtaining ultradispersed powders, synthesis of new materials, as spark leak detectors, for starting gas-discharge light sources, for electric-discharge diagnostics of materials and products, for obtaining gas-discharge photographs by the method of S.D. Kirlian testing the quality of high-voltage insulation. In everyday life, such devices are used as power sources for electronic traps of ultrafine and radioactive dust, electronic ignition systems, for electro-effluvial chandeliers (A.L. ), gas lighters, electric fences, stun guns, etc.

Conventionally, high-voltage generators are devices that generate voltages above 1 kV.

The generator of high-voltage pulses using a resonant transformer (Fig. 11.1) is made according to the classical scheme on the RB-3 gas spark gap.

Capacitor C2 is charged with a pulsating voltage through the diode VD1 and resistor R1 to the breakdown voltage of the gas spark gap. As a result of the breakdown of the gas gap of the spark gap, the capacitor is discharged to the primary winding of the transformer, after which the process is repeated. As a result, decaying high-voltage pulses with an amplitude of up to 3 ... 20 kV are formed at the output of the transformer T1.

To protect the output winding of the transformer from overvoltage, an arrester is connected in parallel to it, made in the form of electrodes with an adjustable air gap.

Rice. 11.1. High-voltage pulse generator circuit using a gas spark gap.

Rice. 11.2. High voltage pulse generator circuit with voltage doubling.

The transformer T1 of the pulse generator (Fig. 11.1) is made on an open ferrite core M400NN-3 with a diameter of 8 and a length of 100 mm. The primary (low-voltage) winding of the transformer contains 20 turns of MGSHV 0.75 mm wire with a winding pitch of 5 ... 6 mm. The secondary winding contains 2400 turns of an ordinary winding of a PEV-2 wire of 0.04 mm. The primary winding is wound over the secondary through a polytetrafluoroethylene (fluoroplastic) gasket 2x0.05 mm. The secondary winding of the transformer must be reliably isolated from the primary.

An embodiment of a high-voltage pulse generator using a resonant transformer is shown in Fig. 11.2. This generator circuit is galvanically isolated from the mains supply. The mains voltage is supplied to the intermediate (step-up) transformer T1. The voltage removed from the secondary winding of the mains transformer is fed to the rectifier operating according to the voltage doubling circuit.

As a result of the operation of such a rectifier, a positive voltage appears on the upper plate of the capacitor C2 relative to the neutral wire, equal to the square root of 2Uii, where Uii is the voltage on the secondary winding of the power transformer.

The corresponding voltage of the opposite sign is formed on the capacitor C1. As a result, the voltage across the plates of the capacitor C3 will be equal to 2 square roots of 2Uii.

The charging rate of capacitors C1 and C2 (C1 = C2) is determined by the value of the resistance R1.

When the voltage on the plates of the capacitor СЗ equals the breakdown voltage of the gas spark gap FV1, a breakdown of its gas gap will occur, the capacitor СЗ and, accordingly, the capacitors C1 and C2 will be discharged, and periodic damped oscillations will occur in the secondary winding of the transformer T2. After the capacitors are discharged and the spark gap is turned off, the process of charging and subsequent discharge of the capacitors to the primary winding of the transformer 12 will be repeated again.

The high-voltage generator used to take photographs in a gas discharge, as well as to collect ultradispersed and radioactive dust (Fig.11.3), consists of a voltage doubler, a relaxation pulse generator and a step-up resonant transformer.

The voltage doubler is made on diodes VD1, VD2 and capacitors C1, C2. The charging circuit is formed by the capacitors C1 - C3 and the resistor R1. Parallel to capacitors C1 - C3, a 350 V gas spark gap is connected with a series-connected primary winding of the step-up transformer T1.

As soon as the level of the constant voltage across the capacitors C1 - C3 exceeds the breakdown voltage of the spark gap, the capacitors are discharged through the winding of the step-up transformer and, as a result, a high-voltage pulse is generated. The circuit elements are selected so that the pulse shaping frequency is about 1 Hz. Capacitor C4 is designed to protect the output terminal of the device from mains voltage input.

Rice. 11.3. High voltage pulse generator circuit using a gas spark gap or dinistors.

The output voltage of the device is entirely determined by the properties of the used transformer and can reach 15 kV. A high-voltage transformer for an output voltage of about 10 kV is made on a dielectric tube with an outer diameter of 8 and a length of 150 mm; a copper electrode with a diameter of 1.5 mm is located inside. The secondary winding contains 3 ... 4 thousand turns of PELSHO 0.12 wire, wound by turn to turn in 10 ... 13 layers (winding width 70 mm) and impregnated with BF-2 glue with interlayer insulation made of polytetrafluoroethylene. The primary winding contains 20 turns of PEV 0.75 wire, passed through a polyvinyl chloride cambric.,

As such a transformer, you can also use a modified line-scan output transformer of a TV; transformers for electronic lighters, flash lamps, ignition coils, etc.

The R-350 gas discharger can be replaced by a switchable chain of KN102 type dinistors (Fig. 11.3, right), which will make it possible to stepwise change the output voltage. To evenly distribute the voltage across the dynistors, resistors of the same rating with a resistance of 300 ... 510 kOhm are connected in parallel to each of them.

A variant of the high-voltage generator circuit using a gas-filled device - a thyratron as a threshold-switching element - is shown in Fig. 11.4.

Rice. 11.4. High voltage pulse generator circuit using a thyratron.

The mains voltage is rectified by the VD1 diode. The rectified voltage is smoothed by the capacitor C1 and fed to the charging circuit R1, C2. As soon as the voltage across the capacitor C2 reaches the ignition voltage of the thyratron VL1, it flashes. Capacitor C2 is discharged through the primary winding of transformer T1, the thyratron goes out, the capacitor starts charging again, etc.

An automobile ignition coil is used as a transformer T1.

Instead of the VL1 MTX-90 thyratron, one or more dinistors of the KN102 type can be switched on. The high voltage amplitude can be adjusted by the number of included dynistors.

The design of a high-voltage converter using a thyratron switch is described in the work. Note that other types of gas-filled devices can also be used to discharge the capacitor.

The use of semiconductor switching devices in modern high voltage generators is more promising. Their advantages are clearly expressed: high repeatability of parameters, lower cost and dimensions, high reliability.

Below we will consider generators of high-voltage pulses using semiconductor switching devices (dinistors, thyristors, bipolar and field-effect transistors).

Dinistors are quite equivalent, but low-current analogue of gas spark gaps.

In fig. 11.5 shows the electrical diagram of a generator made on dynistors. In its structure, the generator is completely similar to those described earlier (Fig. 11.1, 11.4). The main difference lies in replacing the gas spark gap with a chain of serially connected dinistors.

Rice. 11.5. Diagram of a high-voltage pulse generator based on dynistors.

Rice. 11.6. High-voltage pulse generator circuit with a bridge rectifier.

It should be noted that the efficiency of such an analogue and the switched currents are noticeably lower than that of the prototype, but dinistors are more accessible and more durable.

A somewhat complicated version of the high-voltage pulse generator is shown in Fig. 11.6. The mains voltage is supplied to the bridge rectifier on diodes VD1 - VD4. The rectified voltage is smoothed by the capacitor C1. This capacitor generates a constant voltage of about 300 V, which is used to power the relaxation generator, composed of elements R3, C2, VD5 and VD6. Its load is the primary winding of the transformer T1. Pulses with an amplitude of about 5 kV and a repetition rate of up to 800 Hz are removed from the secondary winding.

The chain of dinistors should be designed for a turn-on voltage of about 200 V. Here you can use dinistors such as KN102 or D228. It should be borne in mind that the switching voltage of the KN102A, D228A type dinistors is 20 V; KN102B, D228B - 28 V; KN102V, D228V - 40 V; KN102G, D228G - 56 V; KN102D, D228D - 80 V; KN102E - 75 V; KN102ZH, D228ZH - 120 V; KN102I, D228I - 150 V.

As a transformer T1 in the above devices, a modified line transformer from a black and white TV can be used. Its high-voltage winding is left, the rest are removed and instead of them a low-voltage (primary) winding is wound - 15 ... 30 turns of PEV wire with a diameter of 0.5 ... 0.8 mm.

When choosing the number of turns of the primary winding, the number of turns of the secondary winding should be taken into account. It should also be borne in mind that the value of the output voltage of the high-voltage pulse generator depends to a greater extent on the tuning of the transformer circuits to resonance, rather than on the ratio of the number of winding turns.

The characteristics of some types of line scan television transformers are shown in table 11.1.

Table 11.1. Parameters of high-voltage windings of unified line scan television transformers.

Transformer type	Number of turns		R winding, Ohm
TVS-A, TVS-B
TVS-110, TVS-110M

Transformer type	Number of turns		R winding, Ohm
TVS-90LTs2, TVS-90LTs2-1
TVS-110PTs15
TVS-110PTs16, TVS-110PTs18

Rice. 11.7. Electrical circuit of the high-voltage pulse generator.

In fig. 11.7 shows a diagram of a two-stage high-voltage pulse generator published on one of the sites, in which a thyristor is used as a switching element. In turn, a gas-discharge device - a neon lamp (chain HL1, HL2) - was chosen as a threshold element that determines the repetition rate of high-voltage pulses and triggers the thyristor.

When the supply voltage is applied, a pulse generator based on a VT1 transistor (2N2219A - KT630G) produces a voltage of about 150 V. This voltage is rectified by the diode VD1 and charges the capacitor C2.

After the voltage on the capacitor C2 exceeds the ignition voltage of the neon lamps HL1, HL2, the capacitor will discharge to the control electrode of the thyristor VS1 through the current-limiting resistor R2, the thyristor will be heated. The discharge current of the capacitor C2 will create electrical oscillations in the primary winding of the transformer T2.

The switching voltage of the thyristor can be adjusted by selecting neon lamps with different ignition voltages. You can stepwise change the value of the thyristor turn-on voltage by switching the number of neon lamps connected in series (or dinistors replacing them).

Rice. 11.8. Diagram of electrical processes on the electrodes of semiconductor devices (to Fig. 11.7).

The voltage diagram at the base of the transistor VT1 and at the thyristor anode is shown in Fig. 11.8. As follows from the presented diagrams, the pulses of the blocking generator have a duration of about 8 ms. The charge of the capacitor C2 occurs stepwise-exponentially in accordance with the action of the pulses taken from the secondary winding of the transformer T1.

At the output of the generator, pulses with a voltage of approximately 4.5 kV are formed. An output transformer for low frequency amplifiers is used as transformer T1. As

high-voltage transformer T2 used a transformer from a photo flash or a reworked (see above) television line scan transformer.

A diagram of another version of the generator using a neon lamp as a threshold element is shown in Fig. 11.9.

Rice. 11.9. Electrical circuit of a generator with a threshold element on a neon lamp.

The relaxation generator in it is made on the elements R1, VD1, C1, HL1, VS1. It works with positive loop-periods of the mains voltage, when the capacitor C1 is charged to the turn-on voltage of the threshold element on the HL1 neon lamp and VS1 thyristor. The VD2 diode dampens the self-induction pulses of the primary winding of the step-up transformer T1 and allows you to increase the output voltage of the generator. The output voltage reaches 9 kV. The neon lamp is also a signaling device when the device is connected to the network.

The high-voltage transformer is wound on a piece of a rod with a diameter of 8 and a length of 60 mm from M400NN ferrite. First, the primary winding is placed - 30 turns of PELSHO 0.38 wire, and then the secondary - 5500 turns of PELSHO 0.05 or larger diameter. Between the windings and every 800 ... 1000 turns of the secondary winding, a layer of insulation of polyvinyl chloride insulating tape is laid.

In the generator, it is possible to introduce discrete multistage adjustment of the output voltage by switching neon lamps or dinistors in a serial circuit (Fig. 11.10). In the first version, two stages of regulation are provided, in the second - up to ten or more (when using KN102A dinistors with a turn-on voltage of 20 V).

Rice. 11.10. Electric circuit of the threshold element.

Rice. 11.11. Electrical circuit of a high voltage generator with a threshold element on a diode.

A simple high voltage generator (Fig. 11.11) allows you to get pulses at the output with an amplitude of up to 10 kV.

The switching of the control element of the device occurs at a frequency of 50 Hz (on one half-wave of the mains voltage). The diode VD1 D219A (D220, D223) was used as a threshold element, operating at reverse bias in the avalanche breakdown mode.

When the avalanche breakdown voltage at the semiconductor junction of the diode is exceeded, the diode transitions to the conducting state. The voltage from the charged capacitor C2 is supplied to the control electrode of the thyristor VS1. After turning on the thyristor, the capacitor C2 is discharged to the winding of the transformer T1.

Transformer T1 has no core. It is made on a spool with a diameter of 8 mm made of polymethyl methacrylate or polytetrachlorethylene and contains three spaced sections with a width of

9 mm. The step-up winding contains 3x1000 turns wound with PET wire, PEV-2 0.12 mm. After winding, the winding should be saturated with paraffin. On top of the paraffin, 2 - 3 layers of insulation are applied, after which the primary winding is wound - 3x10 turns of the PEV-2 0.45 mm wire.

Thyristor VS1 can be replaced with another one for a voltage higher than 150 V. The avalanche diode can be replaced with a chain of dinistors (Fig. 11.10, 11.11 below).

The circuit of a low-power portable high-voltage pulse source with autonomous power supply from one galvanic cell (Fig. 11.12) consists of two generators. The first is built on two low-power transistors, the second on a thyristor and a dinistor.

Rice. 11.12. Voltage generator circuit with low-voltage power supply and thyristor-dinistor key element.

A cascade based on transistors of different conductivity converts a low-voltage direct voltage into a high-voltage pulse. The timing chain in this generator is C1 and R1. When the power is turned on, the transistor T1 opens, and the voltage drop across its collector opens the transistor T2. The capacitor C1, charging through the resistor R1, reduces the base current of the transistor Т2 so much that the transistor Т1 goes out of saturation, and this leads to closing and ѴТ2. The transistors will be closed until the capacitor C1 is discharged through the primary winding of the transformer T1.

The increased pulse voltage taken from the secondary winding of the transformer T1 is rectified by the diode VD1 and fed to the capacitor C2 of the second generator with the thyristor VS1 and the dinistor VD2. In every positive half-cycle

the storage capacitor C2 is charged to the amplitude value of the voltage equal to the switching voltage of the dinistor VD2, i.e. up to 56 V (rated impulse unlocking voltage for dinistor type KN102G).

The transition of the dynistor to the open state affects the control circuit of the thyristor VS1, which in turn also opens. Capacitor C2 is discharged through the thyristor and the primary winding of the transformer T2, after which the dinistor and thyristor are closed again and the next charge of the capacitor begins - the switching cycle is repeated.

Pulses with an amplitude of several kilovolts are removed from the secondary winding of the transformer T2. The spark discharge frequency is approximately 20 Hz, but it is much less than the frequency of the pulses taken from the secondary winding of the transformer T1. This happens because the capacitor C2 is charged to the switching voltage of the dinistor not in one, but in several positive half-periods. The value of the capacitance of this capacitor determines the power and duration of the output discharge pulses. The average value of the discharge current, which is safe for the dynistor and the control electrode of the SCR, is selected based on the capacitance of this capacitor and the magnitude of the pulse voltage supplying the stage. For this, the capacitance of the capacitor C2 should be approximately 1 μF.

Transformer T1 is made on a ring ferrite magnetic core of the K10x6x5 type. It has 540 turns of PEV-2 0.1 wire with a grounded tap after the 20th turn. The beginning of its winding is connected to the transistor VT2, the end to the diode VD1. Transformer T2 is wound on a coil with a ferrite or permalloy core with a diameter of 10 mm and a length of 30 mm. A coil with an outer diameter of 30 mm and a width of 10 mm is wound with a PEV-2 wire of 0.1 mm until the frame is completely filled. Before the end of the winding, a grounded tap is made, and the last row of wire of 30 ... 40 turns is wound a turn to a turn over an insulating layer of varnished cloth.

In the course of winding, transformer T2 must be impregnated with insulating varnish or BF-2 glue, then dried thoroughly.

Instead of VT1 and VT2, you can use any low-power transistors that can operate in a pulsed mode. Thyristor KU101E can be replaced with KU101G. Power source - galvanic cells with a voltage of no more than 1.5 V, for example, 312, 314, 316, 326, 336, 343, 373, or disk nickel-cad-mium batteries of the D-0.26D, D-0.55S type etc.

A thyristor high-voltage pulse generator with mains supply is shown in Fig. 11.13.

Rice. 11.13. Electrical circuit of a high-voltage pulse generator with a capacitive energy storage and a thyristor-based switch.

During the positive half-cycle of the mains voltage, the capacitor C1 is charged through the resistor R1, the diode VD1 and the primary winding of the transformer T1. In this case, the thyristor VS1 is closed, since there is no current through its control electrode (the voltage drop across the diode VD2 in the forward direction is small compared to the voltage required to open the thyristor).

With a negative half-cycle, the diodes VD1 and VD2 are closed. A voltage drop occurs at the thyristor cathode relative to the control electrode (minus - at the cathode, plus - at the control electrode), a current appears in the control electrode circuit, and the thyristor opens. At this moment, the capacitor C1 is discharged through the primary winding of the transformer. A high voltage pulse appears in the secondary winding. And so - every period of the mains voltage.

At the output of the device, bipolar high voltage pulses are formed (since damped oscillations occur in the primary winding circuit during the discharge of the capacitor).

Resistor R1 can be composed of three MLT-2 resistors connected in parallel with a resistance of 3 kOhm.

Diodes VD1 and VD2 must be rated for a current of at least 300 mA and a reverse voltage of at least 400 V (VD1) and 100 B (VD2). Capacitor C1 of the MBM type for a voltage of at least 400 V. Its capacity - a fraction of a unit of μF - is selected experimentally. Thyristor VS1 of type KU201K, KU201L, KU202K - KU202N. Transformer - B2B ignition coil (6 V) from a motorcycle or car.

The device can use a TV line scan transformer TVS-110L6, TVS-1 YULA, TVS-110AM.

A fairly typical circuit of a high-voltage pulse generator with a capacitive energy storage is shown in Fig. 11.14.

Rice. 11.14. Schematic of a thyristor high-voltage pulse generator with a capacitive energy storage.

The generator contains a quenching capacitor C1, a diode rectifier bridge VD1 - VD4, a thyristor switch VS1 and a control circuit. When the device is turned on, capacitors C2 and C3 are charged, the thyristor VS1 is still closed and does not conduct current. The limiting voltage on the capacitor C2 is limited by a VD5 Zener diode of 9V. In the process of charging the capacitor C2 through the resistor R2, the voltage at the potentiometer R3 and, accordingly, at the control junction of the thyristor VS1 increases to a certain value, after which the thyristor switches to the conducting state, and the capacitor C3 through the thyristor VS1 is discharged through the primary (low-voltage) winding of the transformer T1, generating a high voltage pulse. After that, the thyristor closes and the process starts over. Potentiometer R3 sets the threshold for thyristor VS1.

The pulse repetition rate is 100 Hz. An automobile ignition coil can be used as a high voltage transformer. In this case, the output voltage of the device will reach 30 ... 35 kV. A thyristor high-voltage pulse generator (Fig. 11.15) is controlled by voltage pulses taken from a relaxation generator, made on a VD1 dinistor. The operating frequency of the control pulse generator (15 ... 25 Hz) is determined by the value of the resistance R2 and the capacitance of the capacitor C1.

Rice. 11.15. Electrical circuit of a thyristor high-voltage pulse generator with pulse control.

The relaxation generator is connected to a thyristor switch through a T1 pulse transformer of the MIT-4 type. A high-frequency transformer from the Iskra-2 darsonvalization apparatus is used as the output transformer T2. The voltage at the output of the device can reach up to 20 ... 25 kV.

In fig. 11.16 shows a variant of supplying control pulses to the thyristor VS1.

The voltage converter (Fig. 11.17), developed in Bulgaria, contains two stages. In the first of them, the load of the key element, made on the transistor ѴT1, is the winding of the transformer T1. Control pulses of a rectangular shape periodically turn on / off the switch on the transistor ѴT1, thereby connecting / disconnecting the primary winding of the transformer.

Rice. 11.16. Thyristor switch control option.

Rice. 11.17. Electrical circuit of a two-stage high-voltage pulse generator.

An increased voltage is induced in the secondary winding, proportional to the transformation ratio. This voltage is rectified by the diode VD1 and charges the capacitor C2, which is connected to the primary (low-voltage) winding of the high-voltage transformer T2 and the thyristor VS1. The thyristor is controlled by voltage pulses taken from the additional winding of the transformer T1 through a chain of elements that correct the pulse shape.

As a result, the thyristor periodically turns on / off. Capacitor C2 is discharged to the primary winding of the high-voltage transformer.

High-voltage pulse generator, Fig. 11.18, contains a generator based on a single-junction transistor as a control element.

Rice. 11.18. Circuit of a high-voltage pulse generator with a control element based on a single-junction transistor.

The mains voltage is rectified by a diode bridge VD1 - VD4. The ripple of the rectified voltage is smoothed by the capacitor C1, the charge current of the capacitor at the moment the device is switched on to the network is limited by the resistor R1. The capacitor C3 is charged through the resistor R4. At the same time, a pulse generator on a single-junction transistor ѴT1 comes into operation. Its "release" capacitor C2 is charged through resistors R3 and R6 from a parametric stabilizer (ballast resistor R2 and zener diodes VD5, VD6). As soon as the voltage across the capacitor C2 reaches a certain value, the transistor ѴT1 switches, and an opening pulse is sent to the control transition of the thyristor VS1.

The capacitor SZ is discharged through the thyristor VS1 to the primary winding of the transformer T1. A high voltage pulse is formed on its secondary winding. The repetition rate of these pulses is determined by the frequency of the generator, which, in turn, depends on the parameters of the chain R3, R6 and C2. The tuning resistor R6 can change the output voltage of the generator by about 1.5 times. In this case, the pulse frequency is adjustable in the range of 250 ... 1000 Hz. In addition, the output voltage changes when the resistor R4 is selected (in the range from 5 to 30 kOhm).

It is advisable to use paper capacitors (C1 and SZ - for a rated voltage of at least 400 V); the diode bridge must be designed for the same voltage. Instead of what is indicated in the diagram, you can use a T10-50 thyristor or, in extreme cases, KU202N. Zener diodes VD5, VD6 must provide a total stabilization voltage of about 18 V.

The transformer is made on the basis of TVS-110P2 from black-and-white TVs. All primary windings are removed and 70 turns of PEL or PEV wire with a diameter of 0.5 ... 0.8 mm are wound on the vacant space.

Electrical circuit of the high voltage pulse generator, Fig. 11.19, consists of a diode-capacitor voltage multiplier (diodes VD1, VD2, capacitors C1 - C4). Its output produces a constant voltage of about 600 V.

Rice. 11.19. Schematic of a high-voltage pulse generator with a mains voltage doubler and a trigger pulse generator on a single-junction transistor.

A single-junction transistor VT1 of the KT117A type was used as a threshold element of the device. The voltage at one of its bases is stabilized by a parametric stabilizer based on a VD3 Zener diode of the KS515A type (stabilization voltage is 15 B). Through the resistor R4, the capacitor C5 is charged, and when the voltage at the control electrode of the transistor VT1 exceeds the voltage at its base, VT1 will switch to a conducting state, and the capacitor C5 is discharged to the control electrode of the thyristor VS1.

When the thyristor is turned on, the chain of capacitors C1 - C4, charged to a voltage of about 600 ... 620 V, is discharged to the low-voltage winding of the step-up transformer T1. After that, the thyristor turns off, the charging and discharging processes are repeated with a frequency determined by the constant R4C5. Resistor R2 limits the short-circuit current when the thyristor is turned on and at the same time is an element of the charging circuit of capacitors C1 - C4.

The converter circuit (Fig. 11.20) and its simplified version (Fig. 11.21) is subdivided into the following units: mains suppression filter (noise filter); electronic regulator; high voltage transformer.

Rice. 11.20. Electrical diagram of a high voltage generator with a line filter.

Rice. 11.21. Electrical diagram of a high voltage generator with a line filter.

The diagram in Fig. 11.20 works as follows. The capacitor SZ is charged through the diode rectifier VD1 and resistor R2 to the peak value of the mains voltage (310 V). This voltage goes through the primary winding of the transformer T1 to the anode of the thyristor VS1. On the other branch (R1, VD2 and C2), the capacitor C2 is slowly charging. When in the process of its charging the breakdown voltage of the VD4 dinistor is reached (within 25 ... 35 V), the capacitor C2 is discharged through the control electrode of the thyristor VS1 and opens it.

The capacitor SZ is almost instantly discharged through the open thyristor VS1 and the primary winding of the transformer T1. The pulsed varying current induces a high voltage in the secondary winding T1, the value of which can exceed 10 kV. After the discharge of the capacitor SZ, the thyristor VS1 closes, and the process repeats.

A television transformer is used as a high-voltage transformer, from which the primary winding is removed. For the new primary winding, a winding wire with a diameter of 0.8 mm is used. The number of turns is 25.

High-frequency ferrite cores, for example, 600HN with a diameter of 8 mm and a length of 20 mm, having approximately 20 turns of a winding wire with a diameter of 0.6 ... 0.8 mm, are best suited for the manufacture of the inductance coils of the barrier filter L1, L2.

Rice. 11.22. Electrical circuit of a two-stage high voltage generator with a field-effect transistor control element.

A two-stage high voltage generator (by Andres Estaban de la Plaza) contains a transformer pulse generator, a rectifier, an RC timing chain, a thyristor (triac) key element, a high-voltage resonant transformer and a thyristor control circuit (Fig.11.22).

An analogue of the TIP41 transistor - KT819A.

Low-voltage transformer voltage converter with cross-feedback, assembled on transistors VT1 and VT2, produces pulses with a repetition rate of 850 Hz. Transistors VT1 and VT2 are installed on heatsinks made of copper or aluminum to facilitate operation when high currents are flowing.

The output voltage taken from the secondary winding of the transformer T1 of the low-voltage converter is rectified by the diode bridge VD1 - VD4 and through the resistor R5 charges the capacitors C3 and C4.

The thyristor switch-on threshold is controlled by a voltage regulator, which includes a KTZ field-effect transistor.

Further, the operation of the converter does not significantly differ from the previously described processes: there is a periodic charge / discharge of capacitors to the low-voltage winding of the transformer, damped electrical oscillations are generated. The output voltage of the converter, when used at the output as a step-up transformer of the ignition coil from a car, reaches 40 ... 60 kV at a resonant frequency of about 5 kHz.

Transformer T1 (line scan output transformer), contains 2x50 turns of wire with a diameter of 1.0 mm, wound bifilarly. The secondary winding contains 1000 turns with a diameter of 0.20 ... 0.32 mm.

Note that modern bipolar and field-effect transistors can be used as controllable key elements.