Non-contact capacitive relay. Scheme, description

Free technical library

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

Contactless capacitive relay. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Radio amateur designer

Comments on the article

The basis of a capacitive relay is a low-power high-frequency generator, similar to the local oscillator of a radio receiver. A metal plate - a sensor - is connected to circuit L1C4 (see diagram). The palm of the hand brought to it represents the second plate of the capacitor CD. The larger the area of its plates and the smaller the distance between them, the greater the capacity of such a capacitor.

Schematic diagram (click to enlarge)

Wind the contour coil L1 on a frame Ø 8-9 mm glued together from paper. The coil contains 22-25 turns of PEV-1 0,3-0,4 wire, wound in one layer turn to turn. Make a branch from the 5-7th turn, counting from the beginning (indicated by a dot in the diagram).

The device operates from a stabilized power supply or from two or three 3666L batteries connected in series.

Connect a milliammeter for a current of 1-5 mA to the collector circuit of transistor V10. And so that the high-frequency component of the collector current does not pass through the device, connect a capacitor with a capacity of 1-2 μF between the connection point of the milliammeter with the coil L0,01 and the emitter V0,5 (shown in the diagram with dashed lines). Temporarily disconnect the sensor from the generator and check its functionality. While watching the milliammeter needle, briefly close circuit L1C4. The collector current V1 should decrease sharply: from 2,5-3 to 0,5-0,8 mA. The highest readings correspond to generation, the smallest to its absence. If the generator is excited, attach a sensor plate to it and slowly move your palm towards it. The collector current will decrease to 0,5-0,8 mA.

Weak current changes are amplified by a two-stage amplifier using transistors V2, V3. And in order to control the load in a non-contact way, the final stage of the capacitive relay is made on the V5 thyristor.

The variable resistor R4 motor is set to its lowest (according to the diagram) position. And then it is slowly moved up until the warning lamp H1 turns on. Now place your palm on the remote plate and check the operation of the capacitive relay as a whole.

Diode V4 in the control electrode circuit of thyristor V5 eliminates the appearance of a reverse voltage pulse. And diode V6 and resistor R7 protect the thyristor from breakdown due to reverse voltage. For a trinistor with an acceptable value of Uо6р. = 400 V elements V6 and R7 can be excluded.

With trinistor KU201K or KU201L, the load current should not exceed 2A.

It is desirable that the load current be slightly lower than the maximum permissible forward current through the thyristor, since its use under extreme conditions reduces operational reliability.

If you use symmetrical triode thyristors (triacs) KU208V or KU208G, the load current can be increased to 4-5 A. And with thyristors KU202ZH, K, L, M, N, you can control the current up to 10 A. At the same time, diode V6 has the maximum permissible value direct current must correspond to the current of the controlled load.

Transistor V1 can be replaced with P401-P403, P416-P416B, P422-P423; V2, V3 - on MP40-MP42, and V8 - on MP37A, MP37B, MP38, MP38A.

Resistors R5-R7 - MLT-2, the rest - of any type.

Capacitors C1-C3 - MBM, C5, C6 - K53-1.

Instead of the V4 diode, D219A, D220, D220A, D220B, or in extreme cases D226 are suitable.

V9-V12 are interchangeable with D7, D226, KD105 with any letter index.

Zener diode V7 can be replaced with D811.

Author: N. Mustafaev

See other articles Section Radio amateur designer.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Primium Seneca keyboard 05.05.2024

Keyboards are an integral part of our daily computer work. However, one of the main problems that users face is noise, especially in the case of premium models. But with the new Seneca keyboard from Norbauer & Co, that may change. Seneca is not just a keyboard, it is the result of five years of development work to create the ideal device. Every aspect of this keyboard, from acoustic properties to mechanical characteristics, has been carefully considered and balanced. One of the key features of Seneca is its silent stabilizers, which solve the noise problem common to many keyboards. In addition, the keyboard supports various key widths, making it convenient for any user. Although Seneca is not yet available for purchase, it is scheduled for release in late summer. Norbauer & Co's Seneca represents new standards in keyboard design. Her ... >>

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. ... >>

Random news from the Archive

Children gain weight in elementary school 08.09.2016

Employees of the Cancer Research Center in the UK conducted a study of the health of younger schoolchildren. They found that after the first grade, many of the children put on a lot of weight. This is worrisome, as obesity leads to many diseases. Scientists urge the UK government to pay attention to the circumstances and take serious measures to preserve the health of schoolchildren.

According to scientists, the weight of schoolchildren is growing every year. Many children do not fit clothes sewn on the average figure of a younger student. This indicates a negative trend. First of all, uncontrolled weight gain leads to cancer. More than 18 British people suffer from cancer every year because of obesity. Also, a lot of weight leads to some genetic diseases. In the end, the general level of health worsens, which is transmitted to descendants.

The researchers suggest that the state take responsibility for schoolchildren. First of all, in the lower grades, it is necessary to increase physical education classes, as well as change the nutrition system. Food should be low in calories. This will help students not to go beyond the average normal weight.

Other interesting news:

▪ PT8 Neo - motherboard based on VIA FSB800 chipset from MSI

▪ Sony Xperia Tablet Z Kitchen Edition

▪ Diagnosing a cold before symptoms appear

▪ Greenhouse vodka

▪ The brightest fluorescent material

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Videotechnique. Article selection

▪ Velcro article. History of invention and production

▪ article Where and when did coughing lead to charges and sentences? Detailed answer

▪ article Siberian bloater. Legends, cultivation, methods of application

▪ article Electric heating boiler control. Encyclopedia of radio electronics and electrical engineering

▪ article Overview of charge recovery schemes for batteries. 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