Homemade amplifier on the TDA7294 chip (part 3). Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Transistor power amplifiers

 Comments on the article

Part I

Part II

Part III

This last part will tell you what I came up with while driving with the results of part two.

The brain of the advanced power supply is still on the SG 3525A. This microcircuit is smarter than its grandmother, no offense to the old woman will be said. SG 3524A has a built-in "slow start" (the time is selected by the capacitance), power down shutdown, etc. The SG 3525A operates at 70 kHz and outputs 35 kHz in turn.

"Brains" of the power supply

"Muscles" of the power supply

(click to enlarge)

The field effect transistor control circuit is made on two transistors (BD 140, BD 139), T8-T11, they beautifully open and close the field effect transistor. C20 and R49 (three Rs of 150 ohms in parallel) will remove unnecessary surges, and almost rectangular pulses will fall on the transformer. The transformer was made on two rings (40 x 24 x 11 - 6000 NM), the primary winding contains 3 turns (3 - 4 mm), I took a double acoustic wire (which is pulled in the car from the amp to the speakers), the secondary winding contains 14 turns ( 4 wires 1 mm each), which is wound first. I tighten the two rings very tightly with electrical tape and wind 4 slightly twisted wires evenly around the circumference of the ring. The ends on one side are ringed on the other side, two wires are selected on one side and on the other, which are not ringed and connected together. In each arm of the reinforced version of the power supply, I put five field-effect transistors IRFZ44 (T12-T21). You can replace them with BUZ11, but they are weaker. I made the bridge on D1-D4 BYW 29/200 diodes, but I also tried it on KD2997A, which, in my opinion, is even better - they do not need radiators.

The PWM is made with decoupling on the TLP504A optocoupler, with such a circuit there is less interference on the TDA 7294. I privatized this circuit either from a French or from an English magazine in the Polish version. The original optocoupler ILD55, but I did not get such a thing.

"Cerebellum", in the sense - SHI modulator

Inductors from the interference of the transformer Tr1, Dr1 and Dr2 wound on 2000NM, with a diameter of 37 mm, 20 - 25 turns (2 mm). Dr3 wound on an even smaller diameter (30 turns 1 mm) - this choke is mainly from interference from the fan that cools the TDA 7294 heatsink, and it should be big and cold, like an iceberg in the ocean.

By technology, if anyone is not scared enough yet. First of all, they assemble the generator on the SG 3525A, always on the socket, you never know, then it will be easier to live. We connect the oscilloscope to the 11th and 14th legs and, making sure that the SG 3525A works and produces rectangular pulses, on the 4th leg we measure F with a frequency meter, on the 11th and 14th legs - too (there is F / 2). Now you can write in the diary that the SG 3525A is working. We solder T8 - T11, and on R33-R34, R35-R36 we watch with an oscilloscope how the control circuit works - of course, there are rectangular pulses at the outputs R33-R34, R35-R36.

Then we solder T12-T21 (preferably also on a pretty radiator - you can't spoil the porridge with oil), solder Tr1. Then we cross ourselves, solder the fuse thinner and turn it on, if the ammeter did not bend the arrow on the right stop, the fuse did not emit, blushing, the last breath and on the secondary winding Tr1 beautiful slightly trapezoidal pulses, then you can shake your own hand. Having charged, C18,18` calm down, and the ammeter needle (for me - at 30 A) returns to the zero position in the x.x mode. (for adjustment, first solder 100 microfarads - so that the ammeter needle does not scare when turned on). Check now if nothing is heating up, the SG 3525A is a little warm, everything else is cold. I do not advise you to touch the secondary winding - there, without a PWM circuit, it can knock, or hit, or even that, as you like. We solder the diode bridge and the PWM circuit on the TLP504A, into the load we solder a 2 W resistor 30 kΩ after C22, C27 into each arm (in the negative arm between "-" and ground, in the other, positive - between "+" and ground).

We set +35 V by adjusting R9, R10, P1. Well, it seems that's all, if I didn't mess up anything in the description, then everything seems to work like that. Or maybe not, it's up to you. It works for me, here is a photo.

"Samopal" in the first edition.

Improved "homemade" in all its glory

Publication: cxem.net

See other articles Section Transistor power amplifiers.

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 HGST Ultrastar SN200 NVMe and SS200 SAS SSDs 13.12.2016 Western Digital introduced solid-state drives for the corporate segment under the HGST brand. The Ultrastar SN200 NVMe series includes 2,5" drives and PCIe expansion cards, while the Ultrastar SS200 SAS series includes only 2,5" drives. The Ultrastar SN200 NVMe series includes the highest capacity drives of its kind in its portfolio. In addition, these drives are characterized by the highest performance. They comply with the PCIe Gen 3 and NVMe 1.2 specifications. Drives are available in capacities from 800 GB to 7,68 TB. In mixed workloads with a 70/30 read/write ratio, they reach 560 IOPS. The Ultrastar SS200 SAS is also the fastest and highest capacity SSD of its kind Western Digital has ever released. It features a 12Gb/s SAS interface that is backwards compatible with 6Gb/s SAS. Drives are available from 400 GB to 7,68 TB in two varieties that differ in resource. The former are designed for one full overwrite daily, the latter can withstand three overwrites per day. Up to 1800MB/s sequential read and 1000MB/s sequential write. The maximum performance on read and write operations with random access is declared equal to 250 and 000 IOPS, respectively. Instant wipe and full encryption options are available. Samples of Ultrastar SN200 NVMe and Ultrastar SS200 SAS drives are already shipping to customers. These products should become widely available in the first quarter of 2017.

Other interesting news:

▪ MAX16831 LED Driver

▪ Mechanism that turns smells into memories discovered

▪ Lynx in the water

▪ Artificial tree purifies water and squeezes it out of the air

▪ Tablet Chuwi HiPad Max

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Life of remarkable physicists. Article selection

▪ Parnassus article. Popular expression

▪ article What information can bees extract from the electric field of flowers? Detailed answer

▪ article New fence. Legends, cultivation, methods of application

▪ article IR remote control turns on electrical appliances. Encyclopedia of radio electronics and electrical engineering

▪ article Capacitors with an organic dielectric. 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