Load switch for sound card. Scheme, description

Free technical library

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

Load switch for sound card. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Audio equipment

Comments on the article

At present, it has become fashionable to connect "home theater" speaker systems to a computer, however, they are distinguished from standard desktop computer speakers not only by an increased number of speakers and a stereo processor, but also by the absence (in most cases) of a headphone jack, which entails inconvenience when changing phones to speakers and vice versa. Connecting them to one jack at the same time, as well as constantly switching plugs in a sound card, is not always convenient for various reasons. To facilitate the manipulation of speakers and headphones, this load switch was assembled.

Sound card load switch
Fig. 1

The appearance of the device is shown in the photo fig. 1. It is a relay switch that connects the selected load to the output of the sound card. The device is located in the system unit and controlled via the COM port.

Sound card load switch
Fig. 2

The scheme of the device is shown in fig. 2. The signal is switched using two electromagnetic relays K1 and K2. The signal arrives at connector XS2 "Input" and, depending on the states of the relay, goes to connector XS1 "Output 1", designed to connect headphones, or XS3 "Output 2" - for speakers. In this design, it is of fundamental importance to which output the speakers are connected, since in the absence of a signal, it is better to connect the input of their amplifier to a common wire in order to avoid noise, this is provided for output 2. The voltage is supplied to the relay through the transistor VT1. The outputs of the COM port have the following voltage levels: log. 1 corresponds to a voltage of -5 ... -15 V, and the log. O - voltage +5 ... 15 V. An electronic key assembled on a transistor VT1 and resistors R1 and R2 must be controlled by a voltage of 0 / + 5 V; to eliminate the voltage of negative polarity, the diode VD1 is included. Diode VD2 protects the transistor VT1 from self-induction EMF when the relay is turned off. I used diodes 1 N4007, but more popular ones, for example KD522B, are also suitable.

The switch uses imported NHG type P-12 relays with two groups of switching contacts. During installation, two unused outer terminals are shortened. Instead of these relays, small-sized 12 V electromagnetic relays with two groups of switching contacts are suitable.

From the diagram in Fig. 2 shows that the device is suitable for sound cards with STEREO output, and most modern sound cards have four or more channels. Therefore, it was decided to supplement the design with two more channels for rear speakers and a subwoofer.

Sound card load switch
Ris.3

The diagram of the additional node is shown in fig. 3, and printed circuit boards of the device - in fig. 4, 5, respectively. The windings of the KZ and K4 relays must be connected in parallel to K1 and K2 (this connection can be made detachable), but it should be noted that the current limit through the KT315A transistor is 100 mA. If the total relay supply current exceeds 80 mA, a more powerful transistor should be used, for example, KT972B, but at the same time changing the resistance of the resistor R1 to 3,9 kOhm and R2 to 1,5 kOhm.

Sound card load switch
Fig. 4

Sound card load switch
Fig. 5

If the device is assembled correctly, then adjustment is not required. However, you will need to install the program required to manage the device. Such a program consists of two files: the directly executable AUDIO_Switch.EXE and the information file Konfig.bak; they both need to be in the same folder. If you open the last file with Notepad, you can find two lines in it; we will be interested in the second. By default, it contains text like ".COM1"; this means that the device is connected to the COM1 port. To use a different port, you need to change the contents of the string, for example, for COM2 it will look like this: ".COM2". The program was written under Windows XR and was not tested under other operating systems. After launch, it immediately minimizes to tray, which saves shortcut space on the desktop, and when it is activated with the right mouse button, you can select the listening method - through headphones or speakers.

Sound card load switch
Fig. 6

A screenshot of the information panel is shown in fig. 6.

Switch management software.

Author: N. Nistratov, Rostov-on-Don; Publication: radioradar.net

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

High performance semiconductor laser from Sharp 03.01.2013

Sharp has announced the release of a semiconductor laser GH0641FA2C with a wavelength of 642 nm and an efficiency of 33% - according to the manufacturer, a record for such devices. The laser is intended for use as a light source in compact projectors and car displays with image projection on the windshield.

The threshold current of the laser LED is 55 mA. With a typical operating voltage of 2,5 V and a current of 182 mA, the optical power is 150 mW. The horizontal and vertical divergence angles are 9° and 17°, respectively.

The manufacturer expects to start deliveries of trial samples of new lasers on January 31, 2013 at a price of about $58 per piece, and from March 29, 2013, serial production of GH0641FA2C in the amount of 10000 pieces per month should begin.

Other interesting news:

▪ LG TVs will stop tracking users

▪ The use of sodium bismuthate will accelerate the development of electronics

▪ Music server on ARM processor

▪ Autopilot of the Chinese search engine Baidu

▪ NXP technology helps save up to 80% on electricity

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Intercoms. Article selection

▪ article Victory has a thousand fathers, but defeat is always an orphan. Popular expression

▪ article What is blood pressure? Detailed answer

▪ article Kopechnik Sakhalin. Legends, cultivation, methods of application