Adjustable voltage / current stabilizer 220 volts / 1,25 ... 25 volts 15 ... 1200 milliamps. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Surge Protectors

 Comments on the article

The source is convenient for powering electronic devices being adjusted and charging batteries. The stabilizer is built according to a compensation scheme, which is characterized by a low level of output voltage ripple and, despite the low efficiency compared to pulse stabilizers, it fully meets the requirements for a laboratory power supply. The circuit diagram of the power supply is shown in fig. 1.

The source consists of a network transformer T1, a diode rectifier VD3-VD6, a smoothing filter C3-C6, a voltage regulator DA1 with an external powerful regulating transistor VT1, a current regulator assembled on the op-amp DA2 and its auxiliary bipolar power supply, an output voltage / load current meter RA1 with switch SA2 "Voltage/'Current".

In the voltage stabilization mode, the output of the op-amp DA2 is high, the HL1 LED and the VD9 diode are closed. Stabilizer DA1 and transistor VT1 operate in standard mode. With a relatively small load current, the transistor VT1 is closed, and all the current flows through the stabilizer DA1. With an increase in the load current, the voltage drop across the resistor R3 increases, the transistor VT1 opens and enters the linear mode, turning on and unloading the stabilizer DA1. The output voltage sets the resistive divider R6R10. By rotating the knob of the variable resistor R10, the required output voltage of the source is set. The current feedback signal is removed from the resistor R9 and fed through the resistor R8 to the inverting input of the op-amp DA2. When the current increases in excess of the value set by the variable resistor R8, the voltage at the output of the op-amp decreases, the VD9 diode opens, the HL1 LED turns on and the stabilizer switches to the load current stabilization mode, indicated by the HL1 LED.

Auxiliary low-power bipolar power supply op-amp DA2 is assembled on two half-wave rectifiers on VD1, VD2 with parametric stabilizers VD7R1, VD8R2. Their common point is connected to the output of the adjustable stabilizer DA1. Such a scheme was chosen for reasons of minimizing the number of turns of the auxiliary winding III, which must be additionally wound on the network transformer T1. Most of the block parts are placed on a printed circuit board made of fiberglass laminated on one side with a thickness of 1 mm. The printed circuit board drawing is shown in fig. 2. Resistor R9 is made up of two 1,5 ohm resistors with a power of 1 watt. Transistor VT1 is mounted on a pin heat sink with external dimensions 130x80x20 mm, which is the rear wall of the source casing. Transformer T1 must have an overall power of 40 ... 50 watts. The voltage (under load) of winding II should be about 25 V, and winding III - 12 V.

With the ratings of the elements indicated in the diagram, the unit provides an output voltage of 1,25 ... 25 V, a load current of 15 ... 1200 mA. The upper voltage limit, if necessary, can be extended to 30 V with a selection of divider resistors R6R10. The upper current limit can also be raised by reducing the shunt resistance R9, but in this case, you will have to install rectifier diodes on the heat sink, use a more powerful transistor VT1 (for example, KT825A-KT825G), and possibly a more powerful transformer. First, a rectifier with a filter and a bipolar power supply for the op-amp DA2 are mounted and checked, then everything else except DA2. After making sure that the adjustable voltage regulator is working, solder the DA2 op-amp and check the adjustable current regulator under load.

The shunt R11 is made independently (its resistance is hundredths or thousandths of an ohm), and the additional resistor R12 is selected for a specific microammeter. My source uses an M42305 microammeter with a full deflection current of 50 µA. Capacitor C13, in accordance with the recommendations of the manufacturer of the stabilizer K142EN12A, it is desirable to use tantalum, for example, K52-2 (IT-1). The KT837E transistor can be replaced by KT818A-KT818G or KT825A-KT825G. Instead of KR140UD1408A, KR140UD6B, K140UD14A, LF411, LM301A or another op amp with a low input current and a suitable supply voltage will do (may require correction of the printed circuit board conductor pattern). The K142EN12A stabilizer can be replaced with an imported LM317T. If it is necessary that the output voltage can be adjusted from zero, you need to add a galvanically isolated additional voltage regulator of 1,25 V to the source (it can also be assembled on K142EN12A) and connect it with a plus to a common wire, and a minus to the right output connected together and the engine of the variable resistor R10, previously disconnected from the common wire.

Author: S. Kolinko, Sumy, Ukraine; Publication: cxem.net

See other articles Section Surge Protectors.

Read and write useful comments on this article.

<< 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 Washing with almost no water 05.12.2008 Many birds are known to enjoy bathing in dust, cleaning their feathers by absorbing dirt into fine mineral particles. A similar effect is used in a washing machine invented at the University of Leeds (UK). The university has created a special company that will start producing such a machine in 2009. Just a glass of water is poured into the machine, in which the washing powder dissolves. Washing is carried out with a mass of thousands of plastic granules with a special surface structure (its details are kept secret) that absorbs dirt from fabrics. A charge of plastic "dust" is enough for a hundred washes, after which it must be changed. The laundry comes out of the machine almost dry, so not only water is saved, but also the electricity needed for drying.

Other interesting news:

▪ Samsung 3,2TB NVMe SSDs with 3D V-NAND Technology

▪ Electronic wine taster

▪ Broadband Internet is an inalienable human right

▪ plastic gold

▪ The blackest color for a BMW car

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Reference materials. Article selection

▪ article To the village, to the wilderness, to Saratov! Popular expression

▪ article Which seafood can cause suffocation when eaten? Detailed answer

▪ article Oxyfuel cutting. Standard instruction on labor protection

▪ article Refinement of the logical probe. Encyclopedia of radio electronics and electrical engineering

▪ article Coin and coin box for manipulation. Focus Secret

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