Encyclopedia of radio electronics and electrical engineering / Civil radio communications

 Comments on the article

One of the problems that arise when operating portable radios is charging batteries. The proposed revision of the standard charger allows you to optimize this process.

Most often, a portable radio battery consists of AA batteries. Their capacity can range from 0,45 Ah (inexpensive domestic) to 1,2 Ah or more (expensive imported). Each of them has its own charging mode, at the same time, one charger (charger) "for all occasions" is included in the radio set. It is usually recommended to charge batteries for 14-16 hours with a current that is one tenth of their capacity. Therefore, it is obvious that such a charger cannot be effective for charging the entire possible range of batteries.

Consider the refinement of the charger on the example of a typical charger. supplied with the Dragon SY-101+ radio. It contains a step-down transformer, a single-diode half-wave rectifier and a smoothing capacitor. The battery compartment of the radio station (Fig. 1) includes an indicator LED601, a current-limiting resistor R602, decoupling diodes D601 and D602, a current-setting resistor R601 and a socket for connecting a memory plug. The value of the charging current is determined not only by the charger itself, but also by the elements of the battery compartment, in particular by the resistor R601.

At the beginning of the charging process (with discharged batteries), the charging current does not exceed 80 ... 90 mA, and at the end - 50 ... 60 mA. Therefore, such a charger can charge batteries with a capacity of 14 ... 0,6 Ah for about 0,65 hours. For batteries with a capacity of 0,5 Ah, the time must be proportionally reduced, and for 0,75 Ah - increased. For batteries with a capacity of 0,9 Ah and even more so 1,2 Ah, the charging time in this case will have to be significantly increased, which is extremely inconvenient and, as a rule, unacceptable.

Therefore, if batteries with a capacity of 0,9 Ah are used

and more, the charging current must be increased. This can be done by installing a lower resistance resistor R601 and modifying the memory. Refinement of the memory is reduced to the installation instead of a half-wave rectifier on one diode of a bridge rectifier on four diodes. In the author's version, this was not difficult, since the modified memory contained a printed circuit board for placing a diode bridge and a capacitor, and only one diode and a capacitor (!) were installed on it. It remained to add three diodes and change one connection point of the capacitor.

This refinement made it possible to increase the maximum charging current by about 15%.

To obtain an average charging current of 120 mA, the resistance of the resistor R601 of the battery compartment must be halved. However, after such refinement, problems arise with charging batteries with a capacity of 0,5. .0,65 Ah - for them this current is large, and you will have to proportionally reduce the charging time. In addition, both before and after such refinement, there is no protection against overcharging, which can lead to a reduction in battery life or even failure.

The way out of this situation can be such a refinement that would allow charging any batteries with a capacity of 0,45 to 1,2 Ah. To do this, a current stabilizer with a switchable stabilization current value must be installed in the memory. The refinement scheme is shown in fig. 2. Chip DA1 is included here according to the current stabilizer circuit, and its value can be changed by switch SA1. The input of the stabilizer is connected to the output of the bridge rectifier. Diode VD1 protects the microcircuit from reverse voltage, and capacitors C1 and C2 ensure its stable operation.

Such a charger can be used to charge batteries without modifying the battery compartment, for this it must be connected to the contacts located below. However, without a special glass, this is inconvenient. Therefore, in the battery compartment, it is necessary to use a resistor R601 with a resistance 3-4 times less or completely close it. In the latter case, the resistor will not interfere with the operation of the charger, but then the LED601 will not light up, signaling charging. However, if the radio station is in a case, then it is still not visible.

To protect the batteries from overcharging, you can install a VD2 zener diode with a stabilization voltage in the range of 13,8 ... 14 V at the output. If you leave the resistor R601, then such overcharge protection will be useless.

The device uses MLT, S2-33, S1-4 resistors, capacitors - K10-17, KLS, KM or similar imported ones. Switch SA1 - any small-sized switch for one direction and several positions (depending on the range of charging current values). The DA1 chip must be equipped with a small heat sink, this will increase the reliability of the device.

There is a lot of free space in the memory case, since the step-down transformer has small dimensions. Installation can be carried out by the hinged method, placing the parts on the terminals of the microcircuit and the switch. Usually, both halves of the memory case are glued together, so first you need to carefully cut a groove 2 ... 3 mm deep along the seam with a sharp scalpel and then separate the case. After installing the parts and checking the performance of the memory, the case is glued again.

Author: I.Nechaev (UA3WIA)

See other articles Section Civil radio communications.

Read and write useful comments on this article.

<< Back

<< 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 Fujitsu's new architecture will speed up PCs by 10 times 24.10.2016 Fujitsu Laboratories has teamed up with the University of Toronto to develop a new computing architecture. This architecture will be aimed at solving combinatorial optimization problems, which includes finding the best combinations of elements among a huge number of combinations. The development uses traditional semiconductor technology in combination with flexible configuration schemes and, according to the creators, is able to solve a wider range of problems compared to quantum computing. Fujitsu has already implemented a prototype system on FPGA elements. According to experimental tests, the new architecture is 10 times faster than traditional computer systems in terms of computing speed. Most likely, what is meant here is performance in solving specific combinatorial problems. The new architecture will make it possible to quickly solve such problems as the rational allocation of resources, improved planning for disaster recovery, the formation of economic policy, and the optimization of the investment portfolio. It will also find application in a variety of decision-making systems. Fujitsu hopes to present a prototype computing system capable of solving real-world problems by 2018.

Other interesting news:

▪ The Ultimate Weapon Against Insects

▪ Ball with a secret

▪ Doctor in your pocket

▪ 7nm 64-core Huawei server CPU and AI SSD controller

▪ Using rain to reduce air pollution

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Children's scientific laboratory. Article selection

▪ article Microphones. Directory

▪ article Who ranks second after the US in agricultural export earnings? Detailed answer

▪ Tornado article. Tourist tips

▪ article Opaque pyroxylin varnish. Simple recipes and tips

▪ article Auto electrician tester. 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