Dynamic filter - noise suppressor. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Dynamic filter - noise suppressor. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Audio equipment

Comments on the article

Dynamic filter - noise suppressor is designed to work in the path of a tape recorder, player, AF amplifier, etc.

(click to enlarge)

The main parameters:

Rated input voltage, mV.......250
Input resistance, MΩ.......1
Suppression of high-frequency noise (with an input signal level of -40 dB at a frequency of 20 kHz), dB not less than.......20
Adjustment range of the threshold level of the input signal, dB.......-40...- 30
Cutoff frequency of the frequency response (with an input signal level of -40 dB), kHz.......1
The steepness of the slope of the frequency response in the suppression band (per octave), dB ....... 6
The slope of the frequency response of the HPF of the control channel (per octave), dB.......20
Harmonic coefficient, %, no more.......0,5
Transmission ratio......0,7

The noise suppressor consists of an input source follower (V1), a controlled low-pass filter (V2, R8, C6), an output emitter follower (V4), an active fourth-order high-pass filter (V5, V6) with an emitter follower at the output (V7) and a rectifier (V8, V9 ) of the filtered signal.

Switch S1 can turn off the device, in this case the signal to the output of the device will come from the load of the source follower (V1).

Instead of KT315B transistors, any transistors of the KT312, KT315 series can be used in the device; it is only important that the specimens intended for operation in the high-pass filter (V5, V6) have a coefficient h2le\u80e 103. The KP103Zh transistor can be replaced with KP103I, KP103K, KP2L by choosing an instance with a cut-off voltage of no more than 521 V. Instead of KD220G diodes, you can use diodes D223, DXNUMX, etc.

Before adjusting, the sliders of all variable resistors and switch S1 are set to the lower (according to the diagram) position. By connecting an oscilloscope or an AC millivoltmeter to the output, an alternating voltage of 2,5 mV with a frequency of 20 kHz is applied to the input. By moving the slider of the resistor R24 up (according to the diagram), the initial bias voltage is set at the gate of the transistor V2, at which it is closed, but is at the threshold of opening (at this moment, the voltage at the output of the device stops decreasing). The correctness of the initial mode setting is checked by increasing the signal voltage to the maximum, for which the slider of the resistor R4 is moved to the upper position. In this case, the output voltage level should increase slightly.

Leaving the slider of the resistor R4 in the upper position, connect a non-linear distortion meter to the output and increase the input signal to 250 mV. The minimum of non-linear distortion is achieved first with a trimming resistor R6, then by selecting a resistor R2 *.

The operating threshold of the device during operation is set by a variable resistor R4.

See other articles Section Audio equipment.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive

Fatty food damages memory 23.01.2016

Fatty food has a bad effect not only on the figure, but also on mental abilities: the experiments of Erica Underwood (Erica Underwood) and Lucien Thompson (Lucien T. Thompson) from the University of Texas at Dallas showed that in mice fed with fat, memory and ability to to learning. The experiment itself was set up as follows: the animals were kept on feed enriched with fats for three months, and then they checked what changes had occurred in the neurophysiology and behavior of the experimental subjects.

In mice on a fatty diet, the excitability of hippocampal neurons decreased - and the hippocampus, as we know, is one of the main memory centers, in particular, memory is consolidated in it, its transformation from short-term to long-term.

Based on the state of neurons that began to work worse, one would expect mice to have worse cognitive abilities. To test this, rodents were placed in a complex toy box, and after the mice got used to the arrangement of objects, one of the toys was placed in a new place. Those of the animals that ate normally quickly learned the new location of objects, but those that were kept on fatty food had difficulty remembering where the familiar thing was now. In other words, memory - at least that part of it that is responsible for orientation in space - having received an excess of fat, really failed. A year later, the learning ability returned to normal, although changes in neurons persisted (probably, some compensatory mechanisms worked).

Of course, other characteristic physiological abnormalities were also observed: for example, in male mice - but not in females - there were symptoms of type XNUMX diabetes, when tissues become less sensitive to insulin and they stop taking glucose from the blood. Since the activity of hippocampal neurons depends, among other things, on insulin, a decrease in the sensitivity of nerve cells to the hormone can affect the work of the neurons themselves and cognitive abilities. Diabetic symptoms in males persisted a year after switching back to normal food.

However, the question remains about females: their memory also deteriorated, and neurons worked worse, but they reacted to insulin in the same way as usual, and even more, sensitivity to the hormone in female neurons increased, and the amount of insulin synthesized decreased (which does not correspond to usual diabetic picture). Why the females here turned out to be different from the males, the researchers have yet to find out - as well as whether something similar happens in humans.

Other interesting news:

▪ Nanoparticles will stop old age

▪ Health record

▪ Microplastics end up in food

▪ New Intel Pentium 4 processor

▪ SN65HVD82 - RS-485 interface with enhanced anti-interference and ESD protection

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Security and safety. Article selection

▪ article Indicators of comfort and human activity. Basics of safe life

▪ article What is a fruit fly? Detailed answer

▪ Kozlik article. Legends, cultivation, methods of application

▪ article Humidity meter with capacitive sensor. Encyclopedia of radio electronics and electrical engineering

▪ article Radio amateur communication technologies based on VoIP. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

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