Quartz chaotic oscillator. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Measuring technology

 Comments on the article

The construction of self-oscillators with "chaotic behavior" is based on the interaction of interconnected linear and nonlinear oscillators.

The scheme of a "chaotic" oscillator usually contains three main elements:

• linear oscillatory circuit;
• a non-linear oscillatory circuit interconnected with a linear one, containing a pn-junction (most often it is a varactor diode);
• an amplifier with a limiting characteristic that provides self-excitation of the system (any amplifier circuit used in conventional self-oscillators).

The nature of the processes in the nonlinear circuit of a chaotic self-oscillator is determined by both the frequency and the amplitude of the impact on it. Complex signals at the output of a non-linear circuit after passing through the self-oscillator feedback circuit become a source of perturbation of the same non-linear circuit. With repeated circulation of the signal, the dynamics of such an oscillator becomes chaotic.

A diagram of a quartz chaotic oscillator, where quartz is used as linear circuits, is shown in Fig. 1. Here, the linear oscillatory circuit is formed by quartz, and the non-linear circuit is formed by elements L1-VD1. Depending on the polarity and level of the RF voltage applied to the varactor diode VD1, its capacitance changes, therefore, the natural (resonant) frequency of the L1-VD1 circuit also changes.

Fig.1. Schematic diagram of a quartz chaotic oscillator

With certain parameters of the system (values ​​of radio components), the oscillations in it become chaotic, and the spectrum of oscillations, discrete up to this point (Fig. 2), becomes continuous (Fig. 3).

Fig.2. Discrete spectrum of vibrations

Fig.3. Continuous spectrum of vibrations

To build a chaotic self-oscillator, the well-known classical scheme of a capacitive "three-point" was used. Transistor VT2 forms a buffer stage, which is necessary for decoupling the oscillator on VT1 and its load (for example, measuring instruments with 50-ohm inputs).

The circuit in Fig. 1 uses two quartz. This is caused by the following. As shown by preliminary experiments, chaotic oscillations are realized in the presence of the L1-VD1 circuit and only one quartz, however, this mode of operation of the oscillator turns out to be extremely unstable.

When the power is turned off and then turned on, the oscillator stops working in a chaotic mode and becomes a "normal" crystal oscillator. A return to the chaotic mode is possible in this case by briefly connecting the second quartz to the one already working in the oscillator.

With the parallel inclusion of several quartzes and the absence of a nonlinear circuit L1-VD1, complex (multi-frequency), but deterministic oscillations occur in the circuit. By connecting a spectrum analyzer to the output of the oscillator, in this case one can see only a certain number of peaks of different heights (Fig. 2). In the presence of two quartz with different frequencies, the oscillations of one quartz modulate the oscillations of the other due to the non-linearity of the amplifier on VT1. The result is an AM signal and a series of harmonics. The more complex the shape of the oscillations affecting the linear circuit L1-VD1, the more likely the chaotic mode. It should be noted that the type of case and the execution of quartz must be identical, and they must differ only in frequency - this is one of the conditions for the oscillator to generate immediately at the frequencies of the quartz installed in it.

The frequencies of quartz should differ by about 1,3 ... 1,5 times. In this case, it is necessary to use quartz with a frequency ratio close to an irrational number. In other words, it is desirable to use quartz with incommensurable frequencies.

To obtain chaotic oscillations, if necessary, it is necessary to select the inductance L1 (as L1, the author used an industrial-made drop-shaped choke with two leads). If chaotic oscillations still do not work, you should try to select capacitors C2 and C3, or change the DC mode of the transistor VT1 using R1.

Having installed a multi-band receiver with AM bands near the oscillator under study and connecting a piece of wire 10 ... The presence of strong noise in a wide frequency band with "inserts" of very powerful carriers indicates that it is the chaotic mode of operation that is implemented.

Instead of a receiver, you can use a special device that allows you to control even the moment of transition from deterministic to chaotic oscillations. The circuit of such a device - an indicator of chaotic oscillations (Fig. 4) - is a detector receiver of AM signals with a 50-ohm RF input and a highly sensitive ultrasonic frequency loaded on headphones.

Fig.4. Scheme of the device-indicator of chaotic oscillations

The indicator is adjusted by selecting the value of the resistor R5 until a voltage of +4 ... 8 V is obtained at the VT2 collector. The indicator input is connected to the generator output. In the presence of chaotic oscillations in the oscillator under study, a very loud noise is heard in the headphones, resembling the "super noise" of a super-generative receiver.

As experiments have shown, in the frequency band 1 ... 25 MHz, the noise power of a quartz chaotic oscillator is 10⁴... 10⁶ times more noise power than the classical zener diode noise generator circuit! This makes it possible to use the quartz chaotic self-oscillator as a heavy-duty noise generator for various measurements.

Literature

1. Moon F. Chaotic oscillations. Introductory course for scientists and engineers. - M.: Mir, 1990.
2. Chaika Yu.D. Deterministic chaos - in the arsenal of a radio amateur. - Radioamatar, 1998, N9, S.12, 13.
3. Maksimov N.A., Kislov V.Ya. Chaotic and regular dynamics of autonomous self-oscillatory systems containing p-n-junction. - Radio engineering and electronics, 1997, N12, S.1487-1492.
4. Artemenko V. SSB minitransceiver with EMF for 160 m - KB magazine, 1997, N6, P.13-21.
5. Chaika Yu.D. A family of self-oscillators of noise oscillations. - Radioamatar, 2002, N8, S.53-55.
6. Davidovich M.V. Bistable stochastic resonance amplifier for low input signal-to-noise ratios. - Radio engineering and electronics, 1996, N11, S.1332-1339.

Author: V.Artemenko, UT5UDJ, Kiev; Publication: radioradar.net

See other articles Section Measuring technology.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The world's tallest astronomical observatory opened 04.05.2024

Exploring space and its mysteries is a task that attracts the attention of astronomers from all over the world. In the fresh air of the high mountains, far from city light pollution, the stars and planets reveal their secrets with greater clarity. A new page is opening in the history of astronomy with the opening of the world's highest astronomical observatory - the Atacama Observatory of the University of Tokyo. The Atacama Observatory, located at an altitude of 5640 meters above sea level, opens up new opportunities for astronomers in the study of space. This site has become the highest location for a ground-based telescope, providing researchers with a unique tool for studying infrared waves in the Universe. Although the high altitude location provides clearer skies and less interference from the atmosphere, building an observatory on a high mountain poses enormous difficulties and challenges. However, despite the difficulties, the new observatory opens up broad research prospects for astronomers. ... >>

Controlling objects using air currents 04.05.2024

The development of robotics continues to open up new prospects for us in the field of automation and control of various objects. Recently, Finnish scientists presented an innovative approach to controlling humanoid robots using air currents. This method promises to revolutionize the way objects are manipulated and open new horizons in the field of robotics. The idea of ​​controlling objects using air currents is not new, but until recently, implementing such concepts remained a challenge. Finnish researchers have developed an innovative method that allows robots to manipulate objects using special air jets as "air fingers". The air flow control algorithm, developed by a team of specialists, is based on a thorough study of the movement of objects in the air flow. The air jet control system, carried out using special motors, allows you to direct objects without resorting to physical ... >>

Purebred dogs get sick no more often than purebred dogs 03.05.2024

Caring for the health of our pets is an important aspect of the life of every dog ​​owner. However, there is a common assumption that purebred dogs are more susceptible to diseases compared to mixed dogs. New research led by researchers at the Texas School of Veterinary Medicine and Biomedical Sciences brings new perspective to this question. A study conducted by the Dog Aging Project (DAP) of more than 27 companion dogs found that purebred and mixed dogs were generally equally likely to experience various diseases. Although some breeds may be more susceptible to certain diseases, the overall diagnosis rate is virtually the same between both groups. The Dog Aging Project's chief veterinarian, Dr. Keith Creevy, notes that there are several well-known diseases that are more common in certain breeds of dogs, which supports the notion that purebred dogs are more susceptible to disease. ... >>

Random news from the Archive There are more microbes in a man's beard than in dog hair 19.04.2019 A man's beard is a receptacle for a huge number of microbes, including potentially dangerous ones. There are more of them in it than in the coat of dogs that are taken out for a walk on the street. It all started when researchers at the Hirslanden Medical Center in Switzerland decided to find out how clean MRI scanners are in regular hospitals. This interest was not accidental. PMRI equipment is periodically used to examine animals, since veterinary clinics do not have their own scanners for various reasons. It turned out that the devices that were sometimes used to examine dogs were cleaner than those used only for procedures with people. After that, experts took swabs from the face of 18 men and from the neck of 30 dogs of different breeds, then comparing the microbial composition of the samples. As a result, they stated: in humans, bacterial "pollution" is more significant than in animals. According to the lead author of the project, Professor Andreas Guzeit, out of 30 domestic dogs that are regularly taken outside, microbes were found in 23 in small quantities. In turn, among the bearded men aged 18 to 76 participating in the study, a high the level of microbes in the hairline was recorded in absolutely everyone. As for potentially dangerous microorganisms, they were found in 7 out of 18 men (38%) and in 4 out of 30 dogs (13%).

Other interesting news:

▪ Moving sidewalks for cities

▪ ultrasonic frog

▪ A new method of observing the Sun

▪ Groats with mushrooms replace polystyrene

▪ By evening the brain shrinks

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Lightning protection. Article selection

▪ article by Ludovico Ariosto. Famous aphorisms

▪ article Why European navigators before 1473 were afraid to approach the equator? Detailed answer

▪ article Operator of a stationary gas filling station. Standard instruction on labor protection

▪ article Tips for users of portable radios. Encyclopedia of radio electronics and electrical engineering

▪ article Laboratory power supply 5 ... 100 volts, 200 milliamps. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024