Improvement of the USB hub. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Computer devices

 Comments on the article

To increase the number of USB ports of a personal computer, laptop, tablet computer or modern TV, external USB hubs (they are also called USB hubs) are used. For this purpose, and also to reduce the likelihood of damage to expensive equipment due to a malfunction of the connected device, two unnamed hubs (Fig. 1) were purchased, designed to connect four devices. In addition to USB sockets, they have a built-in power switch, a power-on LED, and a socket for connecting an external power supply with an output voltage of 5 VDC (not included).

Fig. 1

During the operation of the devices, some of their shortcomings were revealed. It turned out that both middle USB ports work worse than the outer ones; Connecting an external power source to the hub does not turn off power from the USB port of a computer or other device because a non-isolating power jack is installed; Finally, the LED shines too brightly.

To eliminate these shortcomings, the hub was disassembled (for this, it is enough to unscrew two self-tapping screws). The device is assembled on an integrated circuit, designated as LG347086212C. When examining the printed circuit board, it turned out that the blocking capacitors EC1-EC3 (positional designations are indicated on the board), for which there is no place on it. The capacitance of the ceramic blocking capacitor installed in the power circuit turned out to be only about 4,3 microfarads, which is obviously small for such devices.

Fig. 2

A fragment of the scheme of the modified concentrator is shown in fig. 2. The positional designations of the newly introduced elements begin with the prefix 1, the rest correspond to the inscriptions on the board. Oxide capacitors EC1-EC3 with a capacity of 22 uF were installed in the places provided by the manufacturer. To reduce the likelihood of damage to the hub at an increased voltage of the external power source or its "reversal", a protective zener diode 1VD1 was introduced, and in order to reduce the brightness of the LED, the resistor R6 (330 Ohm) was replaced by a 1,2 kOhm resistor.

Blocking capacitors EC1 - EC3 - small-sized oxide aluminum or tantalum with a capacity of 22-47 microfarads in a case with a height of not more than 8 mm. Instead of the KS156A zener diode, you can use KS156G, 2S156A, KS456A, 1N4734A, 1N5339. If an emergency occurs, for example, due to a short circuit, resettable fuses installed on the computer's system board may operate. Since such fuses are usually rated for a current of 1,6 ... 3,6 A, which is a lot, damage to the USB connecting wire is also possible.

In older computers, to protect the USB ports and the power supply from overload, the system boards may not have polymer resettable fuses, but disposable fuses. Due to the lack of a socket with a built-in switch, the power supply scheme had to be changed. Now, when the hub is operating from an external source, power from the computer's USB port can be turned off using the SA1 switch. A 1L1 choke (any small one with an inductance of 22.100 μH and a DC resistance of not more than 0,04 Ohm) is soldered to the printed contacts for connecting the wires coming from the switch, which, together with blocking capacitors, forms an LC filter for the supply voltage.

In conclusion, after a careful examination of the board, the defects of several solderings of the USB socket leads to the printed conductors were eliminated. A view of the installation of the modified device is shown in fig. 3.

Fig. 3

Another drawback of the concentrator came to light. The fact is that to connect it to the computer, an unshielded four-wire cable about 550 mm long was used, on which, when connected to a load concentrator that consumes a current of 0,5 A, about 0,5 V drops. To eliminate this shortcoming, the cable should be replaced , for example, by purchasing a USB 2.0 extension cable for this purpose, in which the power wires (usually in red and black insulation) have a larger diameter and, therefore, less resistance. If it is not possible to purchase such a cable, then the existing one should be shortened to 100.150 mm.

To power devices connected to a universal USB hub, any source with an output constant voltage of 4,9.5,25 V, designed for a maximum load current of 1.1,5 A, for example, the TESA5-0035015dV-B AC adapter included in the kit, is suitable for powering devices connected to a universal USB hub mobile devices (tablet computers, e-books) from Texet with a large LCD screen.

Additional external power may be required if devices with high USB power consumption are connected to the hub, such as an external hard drive, LED flatbed scanner, external USB optical CD reader/writer.

Author: A. Butov

See other articles Section Computer devices.

<< Back

Latest news of science and technology, new electronics:

Artificial leather for touch emulation 15.04.2024

In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>

Petgugu Global cat litter 15.04.2024

Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>

The attractiveness of caring men 14.04.2024

The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>

Random news from the Archive Video on e-books with color ink 28.11.2020 E-readers with E Ink displays have led to a new and extremely convenient class of reading devices in any environment, day or night. The only thing they were unable to do was video playback. The E Ink screen refreshes too slowly. With color, too, it does not add up yet, but video is clearly not the strong point of this technology. The Chinese promise to fix this, and the old Philips research helps them in this. South China Normal University (SCNU) announced the progress in the development of color reflective displays with the ability to show video. Back in 2012, a group for the development of "paper" displays was created as part of the university, led by former Philips engineers. Later, the team began working with a local company, Shenzhen Guohua Optoelectronics Ltd, which is likely to commercialize the development. To date, the efforts of E Ink and other companies that have tried to create an alternative technology for reflective displays in terms of color reproduction and video playback have not led to anything sensible, and two of the most promising technologies - Mirasol and Liquavista - have completely sunk into oblivion. Or not? The most striking thing about the new development of the Chinese is that it is the electrowetting technology brought to mind, which the Dutch Liquavista tried to exploit. However, there is nothing to be surprised here. Liquavista and new Chinese achievements are based on the same developments of Philips researchers. Liquavista went out of business in 2013. China picked up the banner that fell from its hands and now promises to release a commercial product in 2021. These can be portable devices for reading and watching videos that can work for weeks on autonomous power, like regular e-readers on E Ink. But unlike book readers, video on them is played at a high frame rate. At the moment, the developers show two color reflective displays and two monochrome ones, in particular, a 5,8-inch color screen. It is reported to show bright colors in sunlight with good levels of contrast and reflection. The display uses three standard printing colors - cyan, magenta and yellow - to generate color, therefore, as stated, the image quality approaches print. Of the other declared characteristics, you can voice the contrast level - 10:1 (about the same as black and white E Inks) and 40% reflectivity, which is also close to the performance of conventional E Inks.

Other interesting news:

▪ Realistic flight simulator

▪ Traces of Icelandic eruptions

▪ Electronic tongue recognizes food taste

▪ GE Haliade-X Offshore Wind Turbine

▪ Volkswagen Golf new generation

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Firmware. Article selection

▪ article Bakunin Mikhail Alexandrovich. Famous aphorisms

▪ article What prompted Michelangelo to carve his name on one of his sculptures? Detailed answer

▪ Decon article. Legends, cultivation, methods of application

▪ article Hidden wiring indicator. Encyclopedia of radio electronics and electrical engineering

▪ article Protection of stabilizers. 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