Scheme of rectangular pulses. Pulse generator on TL494. FET generators

The generator is a self-oscillating system that generates electric current pulses, in which the transistor plays the role of a switching element. Initially, since the invention, the transistor was positioned as an amplifying element. The presentation of the first transistor took place in 1947. The presentation of the field-effect transistor took place a little later - in 1953. In pulse generators, it plays the role of a switch and only in generators alternating current it implements its amplifying properties while simultaneously participating in the creation of positive feedback to support the oscillatory process.

A visual illustration of the division of the frequency range

Classification

Transistor generators have several classifications:

by the frequency range of the output signal;
by type of output signal;
according to the principle of action.

The frequency range is a subjective value, but for standardization the following division of the frequency range is accepted:

30 Hz to 300 kHz – low frequency(LF);
from 300 kHz to 3 MHz - middle frequency (MF);
3 MHz to 300 MHz - high frequency (HF);
above 300 MHz - ultra high frequency (SHF).

This is the division of the frequency range in the field of radio waves. There is an audio frequency range (AF) - from 16 Hz to 22 kHz. Thus, wanting to emphasize the frequency range of the generator, it is called, for example, a high-frequency or low-frequency generator. The frequencies of the sound range, in turn, are also divided into HF, MF and LF.

According to the type of output signal, generators can be:

sinusoidal - for generating sinusoidal signals;
functional - for self-oscillation of signals of a special form. A special case is a rectangular pulse generator;
noise generators - generators of a wide frequency spectrum, in which, in a given frequency range, the signal spectrum is uniform from the lower to the upper part of the frequency response.

According to the principle of operation of generators:

RC generators;
LC generators;
Blocking generators - short pulse shaper.

Due to fundamental limitations, RC oscillators are usually used in the low and audio ranges, and LC oscillators in the HF frequency range.

Generator circuitry

RC and LC sine wave generators

The generator on a transistor is most simply implemented in a capacitive three-point circuit - the Kolpitz generator (Fig. below).

Transistor oscillator circuit (Colpitz generator)

In the Kolpitz circuit, elements (C1), (C2), (L) are frequency-setting. The remaining elements are a standard transistor piping to provide the necessary DC operation. The same simple circuitry has a generator assembled according to the inductive three-point circuit - the Hartley generator (Fig. below).

Diagram of a three-point generator with inductive coupling (Hartley generator)

In this circuit, the oscillator frequency is determined by a parallel circuit, which includes elements (C), (La), (Lb). Capacitor (C) is needed to form a positive feedback on the alternating current.

The practical implementation of such a generator is more difficult, since it requires an inductor with a tap.

Both self-oscillation generators are mainly used in the MF and HF ranges as carrier frequency generators, in frequency-setting local oscillator circuits, and so on. Radio regenerators are also based on oscillators. This application requires high frequency stability, so the circuit is almost always supplemented with a quartz oscillation resonator.

The master current generator based on a quartz resonator has self-oscillations with a very high accuracy in setting the frequency value of the RF generator. Billionths of a percent is far from the limit. Radio regenerators use only quartz frequency stabilization.

The operation of generators in the region of low-frequency current and audio frequency is associated with difficulties in realizing high values of inductance. To be more precise, in the dimensions of the required inductor.

The Pierce oscillator circuit is a modification of the Kolpitz circuit, implemented without the use of inductance (Fig. below).

Pierce generator circuit without the use of inductance

In Pierce's circuit, the inductance is replaced by a quartz resonator, which made it possible to get rid of the laborious and bulky inductor and, at the same time, limited the upper oscillation range.

Capacitor (C3) does not pass the DC component of the base bias of the transistor to the quartz resonator. Such a generator can generate oscillations up to 25 MHz, including audio frequency.

The work of all the above generators is based on the resonant properties oscillatory system made up of capacitance and inductance. Accordingly, the oscillation frequency is determined by the values of these elements.

RC current generators use the principle of phase shift in an RC circuit. The most commonly used circuit with a phase-shifting chain (Fig. below).

Schematic of an RC oscillator with a phase-shifting chain

Elements (R1), (R2), (C1), (C2), (C3) perform a phase shift to obtain the positive feedback necessary for the occurrence of self-oscillations. Generation occurs at frequencies for which the phase shift is optimal (180 deg). The phase-shifting circuit introduces a strong attenuation of the signal, therefore, such a circuit has increased requirements for the gain of the transistor. The Wien bridge circuit is less demanding on the parameters of the transistor (Fig. below).

Diagram of an RC generator with a Wien bridge

The Wien double T-bridge consists of elements (C1), (C2), (R3) and (R1), (R2), (C3) and is a narrow-band notch filter tuned to the generation frequency. For all other frequencies, the transistor is covered by a deep negative connection.

Functional current generators

Function generators are designed to generate a sequence of pulses of a certain shape (a form describes a certain function - hence the name). The most common generators are rectangular (if the ratio of the pulse duration to the oscillation period is ½, then such a sequence is called a “meander”), triangular and sawtooth pulses. The simplest rectangular pulse generator - a multivibrator, is served as the first circuit for beginner radio amateurs to assemble with their own hands (Fig. below).

Scheme of a multivibrator - a generator of rectangular pulses

A feature of the multivibrator is that almost any transistor can be used in it. The duration of the pulses and pauses between them is determined by the values of the capacitors and resistors in the base circuits of the transistors (Rb1), Cb1) and (Rb2), (Cb2).

The frequency of current self-oscillation can vary from units of hertz to tens of kilohertz. RF self-oscillations on a multivibrator cannot be realized.

Triangular (sawtooth) pulse generators are usually built on the basis of rectangular pulse generators (master oscillator) by adding a corrective chain (Fig. below).

Triangular pulse generator circuit

The shape of the pulses, close to triangular, is determined by the charge-discharge voltage on the plates of the capacitor C.

Blocking generator

The purpose of blocking generators is to generate powerful current pulses with steep fronts and low duty cycle. The duration of the pauses between pulses is much longer than the duration of the pulses themselves. Blocking oscillators are used in pulse shapers, comparators, but the main area of application is the line-scan master oscillator in cathode ray tube-based information display devices. Blocking generators are also successfully used in power conversion devices.

FET generators

A feature of field-effect transistors is a very high input resistance, the order of which is commensurate with the resistance of electronic tubes. The circuit solutions listed above are universal, they are simply adapted to the use of various types of active elements. Colpitz, Hartley and other generators made on a field-effect transistor differ only in the ratings of the elements.

Frequency-setting circuits have the same ratios. To generate high-frequency oscillations, a simple generator made on a field-effect transistor according to an inductive three-point circuit is somewhat preferable. The fact is that the field-effect transistor, having a high input resistance, practically does not have a shunting effect on the inductance, and, therefore, the high-frequency generator will work more stable.

Noise generators

A feature of noise generators is the uniformity of the frequency response in a certain range, that is, the amplitude of oscillations of all frequencies within a given range is the same. Noise generators are used in measuring equipment to assess the frequency characteristics of the tested path. Audio band noise generators are often supplemented with a frequency response equalizer to adapt to subjective loudness to human hearing. Such noise is called "gray".

Video

Until now, there are several areas in which the use of transistors is difficult. These are powerful microwave range generators in radar, and where it is required to receive especially powerful high-frequency pulses. So far, powerful microwave transistors have not been developed. In all other areas, the vast majority of generators are made exclusively on transistors. There are several reasons for this. First, the dimensions. Secondly, power consumption. Thirdly, reliability. On top of that, transistors, due to the peculiarities of their structure, are very easy to miniaturize.

This device will find application in various automation devices for periodic current interruption in load circuits or to generate pulses with widely variable repetition period and duration. Pulse duty cycle can reach several thousand, the period of their repetition and duration - tens of seconds.

When the power supply is turned on (see diagram), all transistors generator closed, the charging of the capacitor C1 begins through the circuit VD1, R3, R H. When the voltage at the emitter of transistor VT1 becomes less than at the base, it will open. Following it, transistors VT2 and VT3 will also open. Now the capacitor C1 will be discharged through the circuit VT2, R4, VT1. After the capacitor is discharged, the transistors will close again and the process will repeat.

In addition to the indicated one, another circuit for discharging this capacitor is introduced into the generator - VT3, R5, VD2. The use of a composite transistor VT2VT3 allows you to increase the resistance of the resistor R4, thereby reducing the influence of the circuit VT2, R4, VT1 on the duration of the discharge of the capacitor C1. At the same time, the generator received a number of advantages compared to the original one; it became possible to regulate the duration of the pulses in a wide range; the dependence of the pulse duration on the period of their repetition has been eliminated; improved shape of output pulses; voltage practically ceased to influence the parameters of the pulse sequence.

The load R H (incandescent lamp, LED, relay winding, etc.) can be connected to both the negative and positive power wires. Transistor VT3 is selected in accordance with the current consumed by the load. There are no special requirements for other elements of the generator.

With the values of the timing elements indicated on the diagram - C1, R3, R4, R5 - the pulse repetition period can be adjusted from 20 to 1500 ms, and their duration - from 0.5 to 12 ms.

A. DRYKOV

Pulse generators are devices that are capable of creating waves of a certain shape. Clock frequency in this case depends on many factors. The main purpose of generators is considered to be the synchronization of processes in electrical appliances. Thus, the user has the opportunity to configure various digital equipment.

Examples include clocks and timers. The main element of devices of this type is considered to be an adapter. Additionally, capacitors and resistors are installed in the generators along with diodes. The main parameters of the devices include the indicator of excitation of oscillations and negative resistance.

Generators with inverters

You can make a pulse generator with your own hands with inverters at home. This adapter will require a capacitorless type. Resistors are best used precisely field. Their momentum transfer parameter is quite high level. Capacitors to the device must be selected based on the power of the adapter. If it output voltage is 2 V, then the minimum should be at the level of 4 pF. Additionally, it is important to monitor the negative resistance parameter. On average, it must fluctuate around 8 ohms.

Rectangular pulse model with regulator

To date, a square-wave generator with regulators is quite common. In order for the user to be able to adjust the limiting frequency of the device, it is necessary to use a modulator. On the market, they are presented by manufacturers of a rotary and push-button type. In this case, it is best to stop at the first option. All this will allow you to more finely tune and not be afraid of a failure in the system.

The modulator is installed in the rectangular pulse generator directly on the adapter. In this case, soldering must be done very carefully. First of all, you should thoroughly clean all contacts. If we consider capacitorless adapters, then they have outputs on the upper side. Additionally, there are analog adapters, which are often available with a protective cover. In this situation, it must be removed.

In order for the device to have a high bandwidth, it is necessary to install resistors in pairs. The oscillation excitation parameter in this case must be at the level. As the main problem, the rectangular pulse generator (the circuit is shown below) has a sharp increase in operating temperature. In this case, you should check the negative resistance of the capacitorless adapter.

Overlapping pulse generator

To make a pulse generator with your own hands, it is best to use an analog adapter. Regulators in this case are not required. This is due to the fact that the level of negative resistance can exceed 5 ohms. As a result, a rather large load is placed on the resistors. Capacitors to the device are selected with a capacity of at least 4 ohms. In turn, the adapter is connected to them only by output contacts. As a main problem, the pulse generator has an asymmetric oscillation, which occurs due to overloading of the resistors.

Device with symmetrical pulses

A simple pulse generator of this type can only be made using inverters. In such a situation, it is best to select an adapter of the analog type. It costs much less on the market than the capacitorless modification. Additionally, it is important to pay attention to the type of resistors. Many experts for the generator are advised to select quartz models. However, their throughput is quite low. As a result, the oscillation excitation parameter will never exceed 4 ms. Plus, the risk of overheating of the adapter is added to this.

Given all of the above, it is more appropriate to use field resistors. in this case will depend on their location on the board. If you choose the option when they are installed in front of the adapter, in this case the vibration excitation index can reach up to 5 ms. In the opposite situation, good results may not be counted. You can check the pulse generator for operability simply by connecting a 20 V power supply. As a result, the level of negative resistance must be in the region of 3 ohms.

To minimize the risk of overheating, it is additionally important to use only capacitive capacitors. The regulator can be installed in such a device. If we consider rotary modifications, then the modulator of the PPR2 series is suitable as an option. According to its characteristics, today it is quite reliable.

triggered generator

A trigger is a device that is responsible for transmitting a signal. Today they are sold unidirectional or bidirectional. Only the first option is suitable for the generator. The above element is installed near the adapter. In this case, soldering must be done only after a thorough cleaning of all contacts.

Directly adapter can be selected even analog type. The load in this case will be small, and the level of negative resistance with a successful assembly will not exceed 5 ohms. The oscillation excitation parameter with a trigger is on average 5 ms. The main problem of the pulse generator is this: increased sensitivity. As a result, these devices are not able to work with a power supply above 20 V.

increased load?

Let's take a look at microchips. Pulse generators of this type imply the use of a powerful inductor. Additionally, only an analog adapter should be selected. In this case, it is necessary to achieve a high throughput of the system. For this, capacitors are used only capacitive type. They must be able to withstand at least 5 ohms of negative resistance.

Resistors for the device are suitable for a wide variety. If you choose them of a closed type, then it is necessary to provide for them a separate contact. If you still stop at field resistors, then the phase change in this case will take quite a long time. Thyristors for such devices are practically useless.

Models with quartz stabilization

The pulse generator circuit of this type provides for the use of only a capacitorless adapter. All this is necessary so that the oscillation excitation index is at least at the level of 4 ms. All this will also reduce thermal losses. Capacitors for the device are selected based on the level of negative resistance. Additionally, the type of power supply must be taken into account. If we consider impulse models, then their output current level is on average at around 30 V. All this can ultimately lead to overheating of the capacitors.

To avoid such problems, many experts advise installing zener diodes. They are soldered directly to the adapter. To do this, clean all contacts and check the cathode voltage. Auxiliary adapters for such generators are also used. In this situation, they play the role of a switched transceiver. As a result, the oscillation excitation parameter is increased to 6 ms.

Generators with PP2 capacitors

The generator of high-voltage pulses with capacitors of this type is formed quite simply. Finding elements for such devices on the market is not a problem. However, it is important to choose a quality chip. Many for this purpose acquire multi-channel modifications. However, they are quite expensive in the store compared to the usual types.

Transistors for generators are most suitable single-junction. In this case, the negative resistance parameter should not exceed 7 ohms. In such a situation, one can hope for the stability of the system. To increase the sensitivity of the device, many advise using zener diodes. However, triggers are rarely used. This is due to the fact that the throughput of the model is significantly reduced. The main problem of capacitors is considered to be the amplification of the limiting frequency.

As a result, the phase change occurs with a large margin. To set up the process properly, you must first configure the adapter. If the negative resistance level is at around 5 ohms, then the limiting frequency of the device should be approximately 40 Hz. As a result, the load from the resistors is removed.

Models with PP5 capacitors

A high-voltage pulse generator with the indicated capacitors can be found quite often. At the same time, it can be used even with 15 V power supplies. Its throughput depends on the type of adapter. In this case, it is important to decide on the resistors. If you select field models, then it is more expedient to install the adapter of the non-condenser type. In that case, the negative resistance parameter will be in the region of 3 ohms.

Zener diodes in this case are used quite often. This is due to a sharp decrease in the level of the limiting frequency. In order to align it, zener diodes are ideal. They are installed, as a rule, near the output port. In turn, resistors are best soldered near the adapter. The oscillatory excitation index depends on the capacitance of the capacitors. Considering 3 pF models, we note that the above parameter will never exceed 6 ms.

Main problems of the generator

The main problem of devices with PP5 capacitors is considered to be increased sensitivity. At the same time, thermal indicators are also at a low level. Due to this, there is often a need to use a trigger. However, in this case, it is still necessary to measure the output voltage indicator. If it exceeds 15 V with a block of 20 V, then the trigger can significantly improve the performance of the system.

Devices on regulators MKM25

The pulse generator circuit with this regulator includes only closed-type resistors. At the same time, even the PPR1 series of microcircuits can be used. In this case, only two capacitors are required. The level of negative resistance directly depends on the conductivity of the elements. If the capacitance of the capacitors is less than 4 pF, then the negative resistance can rise even up to 5 ohms.

To solve this problem, it is necessary to use zener diodes. The regulator in this case is installed on the pulse generator near the analog adapter. The output contacts must be carefully cleaned. You should also check the threshold voltage of the cathode itself. If it exceeds 5 V, then an adjustable pulse generator can be connected to two contacts.

A simple pulse generator on a blinking LED in some cases allows you to assemble a compact device for embedding and controlling powerful LEDs or sound sources.

Pulse generator

Your attention is invited to the simplest electronic circuit with a master oscillator on a flashing LED. First, a little theory about the blinking LED. A blinking LED is a symbiosis of an integrated circuit and the LED itself. In terms of functionality, the microcircuit replaces a timer with high-capacity electrolytic capacitors and is a high-frequency generator and a divider on logic elements at the output of which the frequency decreases depending on the type of flashing LED from units to fractions of Hertz.

How to make a pulse generator with your own hands

The scheme is shown in the figure and is as simple as possible. The supply voltage is 3 volts from two AA batteries, but the circuit will also work from a lithium cell. It is even possible to be powered by a solar battery, similar solutions have already been used in the construction, and garden lights. The load of the LED will be a resistor with a nominal value of 1-3 kOhm, if the value of the resistor changes over a wide range, you can slightly change the blinking frequency. When a flash occurs, a current pulse appears, which can be amplified, the role of the key is played by npn transistor. A load in the form of powerful LEDs, a relay, a motor, or a sound source can be connected to the transistor collector. Absence electrolytic capacitors in the interrupter allowed me to assemble a compact circuit on a small breadboard with my own hands and build it into a robot toy. The lithium round cell just fit into one of the caps. When testing the LED from batteries, be sure to include a current limiting resistor in the circuit. The pinout for turning on the LED is shown in the photo. Watch the video of the circuit.

Generator circuit Pulse generator board

Schematic diagram of the generator of rectangular pulses is shown in the figure. Using the KA7500B PWM controller (TL494 is slightly worse, since there is no 100% PWM control), you can make a good square-wave generator (20 Hz ... 200 kHz) with a duty cycle of 0 ... 100%. In this case, two independent switching circuits can be used using a circuit with a common emitter or a common collector (up to 250 mA and 32 V), or parallel connection (up to 500 mA). If pin 13 is switched from ground to pin 14 (stabilized 5 V), then the outputs will turn on alternately.

According to the documentation, KA7500V should operate at voltage from 7 to 42 V and current at each output up to 250 mA. However, the author's microcircuits "fired" at voltages above 35 V. The microcircuits at the upper limits were not checked for current because of the fear of burning them. The available copies of microcircuits also worked in the frequency range from fractions of a hertz to 500 ... 1000 kHz (in the upper PWM range, naturally, it is worse due to an increase in the total share of time for switching comparators and output switches).

The resistance of the resistor at the input of the generator should be in the range from 1 kΩ to 100 MΩ, but the change in frequency is non-linear. But the change in frequency from the capacitance at the input is linear, at least up to 10 uF big values the author did not try). Setting accuracy or a larger range (from fractions of a hertz to 500...1000 kHz) can be extended by applying more ranges.

[B]LEAS Thank you! Already figured it out. I had 7805 on hand, I made an adjustable 5-13v stabilizer. Everything works, everything is regulated, the amplitude too :))). By the way, at 5 volts it seems to work fine, although according to the datasheet 7v. And 32 v was chosen because, according to the author, "at a voltage above 35 V, the microcircuits" shot "". I just doubt about the 250mA account, although according to the datasheet it is. I made outputs in parallel. In theory, it should be 500mA, but it turns out that I hook a couple of LEDs (load) at the output, they have a consumption of 20mA at a supply voltage of the entire circuit of 12v, the signal amplitude immediately drops to 6v. Is there any other way to increase the current? And how to do it correctly?
Your output stage is an open collector. The output current is determined by a 1k resistor according to the circuit going to 8.11 legs. Accordingly, the maximum current flowing through the circuit + Pit-> 1000 ohm-> chip transistor-> ground will be 12 milliamps at 12V supply. Where do you get 6 volts in the circuit and with what device did you measure this value? AND general nutrition doesn't fail? The timer KR1006VI1 can be used as a buffer. Output up to 200 milliamps.
General nutrition does not fail, it is stable. Here's what I get (in attack) In this version, what is on one, what is on the other figure is the power supply of the 13v circuit. On one, without load, and the signal amplitude is somewhere around 11.5-12v (1v / div on the probe 1:10) on the other, respectively, with a load of 15ma, the amplitude after connecting the load dropped to 6-7v. As a load, I used a simple LED connected through a 1k resistor. I tried to select the cutters, if you set it to less than 300 ohms, then the microcircuit and the cutter start to heat up (it's understandable), and if it's higher, the current is small. In principle, while I got out, I stuck the first transistor that came to hand at the output, the current became larger, 150mA, I haven’t checked it yet. A little later, I'll be freer, I'll try to put a buffer. Well, in principle, I figured out my questions. Once again, many thanks to all who replied! And a HUGE THANK YOU!!! [B]LEAS-y. Without his help, I would have been tinkering with this scheme for a long time.
You probably realized that instead of a toggle switch in the pictures, a signal is supplied from your generator. And with the load, draw how everything is connected. So I'm not really going to put something together. Good luck in creativity.
[B]LEAS Yes, I understand at the expense of 555. I draw :)))) (in attack) in the first figure, an LED is hooked up as a load. And accordingly, when it is connected, we get such a signal amplitude, as I laid out above. In another figure, I put a tranzyuk on the output (I just don’t know if I did it right or wrong, but it seems to work) I checked at a current of 150 mA, nothing gets warm, everything works. It only turns out that at the output of the protection there is no short on the body and all hello to the transit. Unlike the KA7500, it turned out to be tenacious, as soon as I didn’t experiment on it :)))))) I tried without a transistor, using only a microcircuit, reduced the cutters (which are powered by the output of the mikruha, up to 150 ohms) the current of course rose, but also the cutter and the microcircuit is very hot. on this stuck a transistor. Just for now, 150mA is enough for me. But ideally, I need 500mA, and I also want output protection, how can this be achieved?
If you measured relative to the ground on the LED according to your switching circuit, there will be about 6-7 volts, depending on the instance of the LED. I wrote to you, but you apparently did not pay attention. The internal transistors of the microcircuit only connect the connection point R7, R8, HL1 to ground and that's it. And there is no transistor that connects power to this point. Its role is played by R7, R8 connected to the power supply. When the internal transistor is closed, you get just a resistive divider. Mentally remove the LED - at this point it will be this divider. You can still like this, the upper terminals of the resistors, respectively, power.
Thank you! I understand about the divider. You just asked what and where I connected, so I answered. Yes, there, by the way, in my drawing with a transic, in my opinion, when I drew the emitter with the collector, I mixed it up in places. And I also installed a cutter to limit the output current, it's just not in the picture. LEAS, but in this version, why is the diode used?
Well, why, a reverse conductance bipolar transistor will open (call-emitter junction) if the base potential is higher than the emitter potential. A low emitter potential will provide a load, and a high base potential will provide a voltage from the resistor. If the diode is thrown out, then the base and emitter potentials will be the same (this is what the diode prevents) and the whole circuit will again be reduced to a resistive divider - the transistor will not work.
It is necessary to leave the 16th leg in the air, and solder the 15th and 7th to the power minus.
Hello everyone. Guys, I will advise a link for TL494: skif_biz article "TEG experiment to extract energy from the field of a permanent magnet." Good luck
Can someone throw out the layout in lay format for the generator? Otherwise, damn it, it’s a shame to say of course, but I can’t do anything (((Still, someone else can tell me to chime simple, I need to generate a frequency from 60 to 140 hertz and a duty cycle ... I don’t need the rest of the range, moreover, it will be inconvenient to adjust the device ... thanks in advance.
There was an error in the laid out circuit - 7 output should be on the minus .... http://i031.radikal.ru/0805/b8/93dfefe80a28.jpg _http://forum.cxem.net/index.php?showtopic=13268&st=0 ============== =========================================== Universal generator on TL494 (rectangle and saw) - an improved version from "Datagor" ... . :) _http://forum.cxem.net/index.php?showtopic=13268&st=320
Tell me, what formulas were used to calculate the nominal values of the circuit? Interesting
By datasheet.
I've looked at the datasheet, but somehow I don't quite catch the connections. maybe someone can show with an example how to calculate the scheme with a datik (they didn’t teach this at the university), or tell me where you can look at such an example, I would be very grateful. http://archive.espec.ws/files/TL494.PDF
What sensor are you talking about?
STRV meant probably a datasheet, yes, they don’t teach them to read at the university, they used to teach to think there ... I don’t know how it is now.
Well, as if everything in general terms. but as it comes to specific tasks, the question "so what?" gets up. I’m not a C student, but still a lot is incomprehensible. We didn’t have any practice of calculations as such.
The datasheet contains ALL the calculated and time parameters! Read\look CAREFULLY! Good luck.
on almost any microcontroller with PWM, you can make a similar generator that will work stably. An example of such a generator is, for example, in the journal "Electronics and Programming Laboratory" No. 1-2. http://journal.electroniclab.ru/journal_content_001.htm http://journal.electroniclab.ru/journal_content_002.htm