Laboratory power supply 0...20 volts. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Power Supplies
Comments on the article
Under this heading, in Radio, 1998, No. 5, a description of a simple power supply based on KR142 series microcircuits was published. A feature of the new version of the block is the ability to smoothly set the threshold for limiting the output current from a few milliamps to the maximum value.
The main difference of the modified power supply (Fig. 1) is the introduction of the DA2 operational amplifier and the installation of a negative voltage stabilizer chip of -6 V instead of -1.25 V. While the output current is small and the voltage drop across the current-measuring resistor R2 is less than that set by the resistor R3, there are 6 op-amps at the output and at the input of the DA1 microcircuit (pin 2) the voltage values are approximately equal, the diode VD4 is closed and the op-amp does not participate in the operation of the device. If the voltage drop across the resistor R2 becomes greater than that across the resistor R3, the voltage at the output of the DA2 chip will decrease, the VD4 diode will open and the output voltage of the unit will decrease to a value corresponding to the set current limit. The transition of the unit to the current stabilization mode is indicated by the HL1 LED turning on.
Since in the short circuit mode, the output voltage of the op-amp should be less than -1.25 V by about 2.4 V (voltage drop across the VD4 diode and HL1 LED), the voltage of the negative power supply of the op-amp was chosen to be -6 V. This value is necessary for all positions of the SA2 switch, therefore I had to switch the input of the rectifier VD2, VD3.
The KR1168EN6B microcircuit can be replaced with a similar one with index A, with MC79L06 with indices BP, CP and ACP, as well as with KR1162EN6A (B) (see article: Nefedov A., Valyavsky A. "Microcircuit stabilizers of the KR1162 series" in "Radio", 1995, No. 4), KR1179EN06, AN7906, µA7906, but they have larger dimensions and distance between the terminals (like KR142EN12A). The pinout matches. The K140UD6 microcircuit is interchangeable with KR140UD608, K140UD7, KR140UD708. The LED can be any type of red glow. Resistor R2 - four C2-29B 2 ohm, 0.125 W connected in parallel. There are no requirements for the accuracy of its resistance, so the resistor can be made independently from a piece of high-resistance wire. Resistor R12 - SP3-19a. The remaining elements are the same as in the main version of the block, the design is similar. A drawing of the printed circuit board is shown in Fig.2.
The resistances of resistors R3 and R4 may differ from those indicated in the diagram by a factor of two, it is only important that their ratio is 1:10. Resistor R3 can also be replaced by two connected in series, and the resistance of the second should be 5 ... 10% of the first, this will facilitate the precise setting of the limiting current.
When setting up the unit, by selecting the resistor R7, the output voltage is set to 20 V and by adjusting R12 - 0 V. Since these operations are interdependent, they must be repeated several times.
In the current stabilizer mode, switch SA2 should be set to the position corresponding to the minimum voltage at which the required load current is provided. The unit will stabilize the current even at a higher voltage, but the power allocated to the DA1 chip will exceed the maximum allowable (10 ... 12 W), and the thermal protection built into the DA1 chip may work.
Publication: N. Bolshakov, rf.atnn.ru
See other articles Section Power Supplies.
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 Noise Buds VS104 Max TWS Silent Headphones
26.07.2023
The revolutionary Noise Buds VS104 Max TWS wireless headphones have hit the market with up to 25 dB of ambient noise cancellation for amazing sound. With 13mm drivers, these headphones deliver an incredible audio experience.
Bluetooth 5.3 with Hyper Sync technology instantly pairs the headphones with your smartphone as soon as you open the charging case cover.
The Noise Buds VS104 Max also provide Active Noise Cancellation that reduces external noise by up to 25 dB, creating a unique atmosphere for enjoying music. In addition, the presence of a transparency mode allows you to hear the world around you without removing your headphones.
Four built-in microphones and Environmental Noise Control (ENC) technology ensure high-quality communication during calls and online meetings. Low latency, supported in game and video mode, provides near-instantaneous audio synchronization down to 50ms.
With an impressive battery life of up to 45 hours (including the charging case) and innovative Instacharge technology that allows you to quickly charge your headphones in just three hours of use with just a 10-minute charge, the Noise Buds VS104 Max will be a reliable companion in any conditions. Additionally, they are IPX5 water resistant, making them a great choice even during intense workouts.
|
Other interesting news:
▪ Completely invisible ink
▪ Microcontrollers Microchip PIC18F-Q41
▪ Headphones Logitech G Fits
▪ The danger of e-waste
▪ Micron phone camera sensor
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ site section Power regulators, thermometers, heat stabilizers. Article selection
▪ article In the middle of nowhere. Popular expression
▪ article How far is the nearest star from us? Detailed answer
▪ article Head of the railway station. Job description
▪ article Flasher on an incandescent lamp. Encyclopedia of radio electronics and electrical engineering
▪ article Rings connect and separate. Focus Secret
Leave your comment on this article:
All languages of this page
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua
2000-2024
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese