Audio-video signal distributor. Scheme, description

Free technical library

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

Audio-video signal distributor. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Телевидение

Comments on the article

When re-recording video cassettes, it is often necessary to send an audio-video signal (AV) to several VCRs at once. A similar problem arises if an AV signal from one source (VCR, camcorder) needs to be fed to several monitors.

You can solve such problems with the help of an audio-video signal distributor. One of the options for such a device with four AV outputs was described in the article by I. Nechaev "Splitter of video and audio signals" ("Radio" 1999, No. 1 p. 13). It uses the AD812AN chip from Analog Devices, which is a powerful two-channel high-speed op amp. If there are problems with the acquisition of this microcircuit, then the AV signal distributor can also be assembled on transistors.

A diagram of a simple similar device is shown in the figure. It allows you to connect up to four VCRs or monitors (TVs) to one AV signal source.

AV Distributor

The AV signal is fed to the distributor through the X1 connector (in this case, the SCART type). Since the input impedance of the audio inputs of VCRs and TVs is relatively high, the problem of distributing the audio signal (removed from pins 6 and 2 of connector XI) is solved by simply introducing an appropriate number of conventional emitter followers on low power transistors. They are made on transistors VT7-VT10 and to simplify the device by bias circuits are combined into two groups. The maximum input voltage for the audio path is about 2 V.

Since the video input of a VCR is a low-resistance load (usually 75 ohms), solving the problem using a single-transistor emitter follower is impractical. In order to ensure a transmission coefficient close to unity, in this case it must be performed on a relatively powerful high-frequency transistor. The author of the described AV signal distributor took a different path. He made repeaters on conventional low power transistors (VT3-VT6). which, due to the presence of terminating resistors R16-R19, provided a transfer coefficient slightly less than 0,5. and the loss of the video signal level was compensated by a common broadband preamplifier for all four channels based on transistors VT1 and VT2 with a gain of about three.

The output signals from the repeaters are fed to four groups of three-pin AV output connectors (BB1-BAI - common wire. BB2-VA2 - common wire, etc.). They can be of the same type, but if a radio amateur uses equipment with different types of connectors, then such a distributor can also be used as a kind of "adapter". In this case, connectors of different types (BNC, DIN, RCA, etc.) are connected to each of the channels.

Transistors VT1. VT3 - VT10 can be replaced with any low-power high-frequency n-p-n transistors, for example, KTZ102B. Transistor VT2 - any high-frequency silicon pn-p transistor of low power, for example KT3107B. Diodes VD1 and VD2 - any high-frequency low power, for example KD503A. When working with stereo sound sources, it is necessary to install decoupling resistors with a resistance of 2 kOhm each in series in the circuit of outputs 6 and 1 of connector X1.

Author: Jural Vajdullak

See other articles Section Телевидение.

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

Bathers in the middle of the desert 13.01.2007

For most of its history, the Sahara has been a desert. Approximately every one hundred thousand years, due to the peculiarities of the Earth's orbit and the change in its axial tilt, this part of Africa experiences a wet period lasting about 5000 years.

German geologists and archaeologists working in the east of the Sahara discovered that only 5500 years ago there was a savannah with rich vegetation and lakes on the site of the desert. Then the rains became rare, and the population had to migrate east to the Nile Valley, where, thanks to this change in climate, the great civilization of Egypt was born.

Archaeologists have found rock paintings depicting people swimming in the lake. Two of them have something like flippers on their legs.

Other interesting news:

▪ Eco-friendly replacement for plastic bottles

▪ solar phone

▪ DC/DC Converters L598x

▪ Ultra-thin flexible safety glasses

▪ Device against decompression sickness

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Firmware. Article selection

▪ article No rules without exceptions. Popular expression

▪ article Can a car break the sound barrier? Detailed answer

▪ article Roofer of rolled roofs and roofs made of artificial materials. Job description

▪ article Coaxial dummy load. Encyclopedia of radio electronics and electrical engineering

▪ article Antenna amplifier Kus = 38...41 dB. 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