Bridge transistor rectifier. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Voltage converters, rectifiers, inverters

 Comments on the article

Many radio amateurs accumulate a large number of radio components over time, usually obtained by disassembling old radio equipment. Since the parameters of modern components are much better than their counterparts developed in the 60s ... 70s of the last century, many of these parts have been dead weight for many years. One of these unclaimed parts often turn out to be powerful germanium pnp transistors P213 ... P217. Previously, they were used in the output stages of audio frequency power amplifiers, voltage converters and stabilizers, in the output stages of vertical scanning modules, etc.

At present, these transistors are not suitable even for low-class UMZCH, and it is more reliable to use silicon field-effect and bipolar transistors for stabilizers and voltage converters. When it is still a pity to throw away such transistors, they can be adapted as rectifier diodes. If the base and emitter terminals of such a transistor are connected together, it will become a germanium rectifier diode.

The collector terminal will be the anode and the base terminal will be the cathode. The advantage of germanium diodes over silicon ones is a lower saturation voltage (Unac). The table shows the values ​​of Unas For different values ​​of forward current (Ipr) through the germanium transistor P216G, diodes KD213A, D246A, KD202K, imported low-power Schottky V81 diode and a common imported diode 1N4001 (1N4002 ... 1N4007). As can be seen from the table, the voltage and power losses on the germanium transistor diode are the smallest. The popular diode 1N4001 turned out to be the worst in terms of efficiency, but, in fairness, it should be noted that it is also the lowest-powered diode from those given in the table.

The figure shows a diagram of a simple power supply with a bridge rectifier based on P216G transistors. It is most expedient to use such rectifiers in power supplies for rectifying alternating voltage 3 ... 12 V. For example, in network adapters for powering children's self-propelled toys. Replacing a silicon rectifier with a germanium one allows you to increase the voltage across the filter capacitor by 1 ... 1,5 V or by several watts (at a current of more than 1 A) to reduce power losses in the rectifier, so that a step-down transformer can be taken with less power. If a low-voltage rectifier is required for a load current of up to 50 ... 100 mA, then low-power germanium transistors MP25, MP26 can be used in diode switching.

Unfortunately, high-power transistors are larger than Schottky diodes and allow less heating of the case. This is compensated for where the size of the parts is not critical, because. the actual cost of transistors tends to zero. The case temperature of the germanium transistor should not exceed 50...55°C. With a load current of more than 2,5 A, it is better to install the transistors on a heat sink, and provide the power supply with good ventilation.

Fuse FU2 - self-resetting, for example, MF-R300 11]. Transformer T1 can be taken industrially, for example, TP-114-1 or the TAN series [2. 3] with an open circuit voltage on the secondary winding of 7.8 V, and at a load current of 2.1 A - about 6,3 V.

Among the powerful germanium transistors recovered from old radio equipment, there are often faulty ones. If the base-emitter junction is broken, such a transistor can still be used as a rectifier diode. But when "only the case" remains from the transistor, it will also serve. The leads are cut off from the case, a hole with a diameter of 3 ... 3.5 mm is drilled in it (for the M3 screw), and it turns ... into a small heat sink for transistors of the KT815 series. KT961 and similar.

Literature

1. modern fuses. - Radioworld. 2008. Nos. 3-4.
2. Power transformers. - Radioamator. 2005, No. 3. P.31.
3. Power transformers type TAN. - Radiomir, 2003. No. 1-2.

Author: A. Butov, village of Kurba, Yaroslavl region

See other articles Section Voltage converters, rectifiers, inverters.

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 Keeping milk fresh without pasteurization 11.05.2019 An Australian company has developed the world's first milk processing technology that preserves its 60% naturalness and keeps it fresh for more than XNUMX days. This milk is safe for human consumption. Naturo's technology has been approved by the Australian Food Safety Authority, Dairy Food Safety Victoria (DFSV), "as an alternative way to pasteurize raw milk". The technology has also been independently tested and approved by Australia's leading organization for scientific and applied research. The technology itself aims to kill the bacterium Bacillus cereus, a common but unwanted spore that produces bacteria in milk. These bacteria produce toxins that cause vomiting or diarrhea. Recent studies show that the milk remained fresh and fit for human consumption after the completion of the 91-day testing period, compared to only 14 days for standard fresh pasteurized milk. Naturo's patented technology allows milk to be transported by ship, rather than by air, to markets around the world, including Japan, China, Malaysia, Singapore and Indonesia. So far, the technology has only been tested on cow's milk. However, there is a prospect of application to other types of milk, including camel, goat, sheep and others. Today, Naruto is seeking investment for a pilot plant in Australia capable of processing 10 million liters of milk per year. The plant will allow the company to create industrial facilities that will produce products under its own brand, focused on the domestic and Asian markets. Naturo recently received $250 from the Queensland government to support technology development.

Other interesting news:

▪ Contact lenses that project information into the eyes

▪ ADE7758 and ADE7753 Energy Metering Chips

▪ Intel Haswell processors with DirectX 11.1 support

▪ Children constructor

▪ Quantum teleportation 44 km

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the website Audiotechnics. Article selection

▪ article If they don't have bread, let them eat cake! Popular expression

▪ article Where did the coconut originate? Detailed answer

▪ article Decorator of finished products. Standard instruction on labor protection

▪ article Balance modulator on varicaps. Encyclopedia of radio electronics and electrical engineering

▪ article Charger. 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