Economic stabilizer with protection system. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Economic stabilizer with protection system. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Surge Protectors

Comments on the article

Voltage stabilizers with a falling characteristic of the protection system have the ability to automatically return to the voltage stabilization mode after the overload cause has been eliminated; relatively little power is dissipated on the regulating element in the load closing mode.

Such a stabilizer usually contains a reference voltage source, a differential amplifier, a protection system, and a control element on a composite transistor. The protection system includes a load current limiter and a circuit with a zener diode connected in parallel to the regulating element. This circuit forms the falling section of the load characteristic. The load current limiter is built on a current-measuring resistor connected between the base and the emitter of the transistor, shunting the emitter junctions of the regulating element.

The disadvantage of these stabilizers is a significant difference between the input and output voltages, which is necessary for the normal operation of the device. It consists of a voltage drop across the current source in the collector circuit of the differential amplifier and the emitter junctions of the compound transistor of the regulating element and is approximately 3 V. Such a large value does not allow achieving a high efficiency of the device, especially at low output voltage. For example, a 5-volt regulator made according to a similar scheme will have an efficiency of about 60%.

The voltage drop across the stabilizer can be reduced to 1 ... 1,5 V if a germanium transistor is used in the current source in the collector circuit of the differential amplifier, and a composite transistor with additional symmetry is used in the control element.

Even more increase the efficiency of the stabilizer allows its construction according to the scheme "with low loss voltage". The composite control transistor must be connected here according to the circuit with a common emitter with respect to the load, therefore, the inverting output of the differential amplifier is used to control the control element. In this case, there is no need for a current source, since the collector current from this output of the differential amplifier directly serves as the base current of the composite transistor of the regulating element. The minimum difference between the input and output voltages, sufficient for the normal operation of the stabilizer, is equal to the voltage drop across the current-measuring resistor plus the saturation voltage of the output transistor and does not exceed 1 V.

There is only one way to further reduce the loss voltage on the stabilizer - by reducing the voltage drop across the current-measuring resistor. This possibility is implemented in the stabilizer, the scheme of which is shown in Fig.1.

(click to enlarge)

Resistor R2 of the protection device is included in the current source circuit, made on a field-effect transistor VT2. The maximum output current Imax of the stabilizer is determined by the expression Imax ~ (0,6-UR2) / R1, where UR2 is the voltage drop across the resistor R2.

By selecting resistor R3, the current through resistor R2 is set to 1 mA. Thus, the maximum voltage drop across the resistor R1 is approximately 0,2 V.

The main technical characteristics of the stabilizer:

Stabilization factor......500
Output impedance, Ohm.......0,5
Maximum load current, mA.......100
Input voltage, V.......9,3...15
Output voltage, V ....... 9
Ripple suppression coefficient, dB.......55
Efficiency at an input voltage of 9,3 V,%.......93

Temperature coefficient of the output voltage, %/° С ~ -0,35 The type of load characteristics of the stabilizer at different values of the input voltage is shown in Fig. 2.

Economic stabilizer with protection system
Ris.2

The limits for changing the input voltage can be expanded upwards by using a VD2 zener diode with a higher stabilization voltage. In this case, however, the load characteristic will change somewhat.

The stabilizer has a certain versatility. The output voltage can be changed by selecting the resistor R6 in the range from Uo6p + (2 ... 3) V to the maximum allowable voltage Uke of the transistors used (Uobr - reference voltage). These 2 ... 3 V are necessary for the operation of the current source collected on the transistor VT2. The required form of the load characteristic is achieved by a selection of elements VD2 and R7. The maximum load current is set by selecting the resistor R1. Without any changes, the stabilizer can operate at a load current of up to 1 A. With an even higher current, the composite regulating transistor should no longer be double, but triple - an even more powerful transistor will have to be added.

The stabilizer can also use other low-power silicon transistors of the appropriate structure, suitable for voltage. The KT814A transistor can also be replaced by another, pnn structure, designed for the corresponding power dissipation. Use transistors with low saturation voltage.

The described stabilizer can be recommended for use in devices where the requirements for the stability of the output voltage are moderate, and the main factors are high efficiency and the presence of protection against overloads and short circuits in the load with automatic return to operating mode after the overload is eliminated.

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

The sun desalinates the water 02.01.2010

On the scale of our planet, the Sun works as a natural desalinator, evaporating water from the oceans. German engineers from the company "Heliotech" forced our luminary to work in the same position, but on a smaller scale.

Sea water is poured into a system of glass tubes exposed to the sun. Air pressure is reduced in the tubes so that the water boils at a low temperature. Here it evaporates, and in another compartment of the system, located in the shade, it condenses. From time to time it is necessary to clean the pipes from the accumulated sea salt.

The module, measuring 220x200x190 centimeters and weighing 200 kilograms, produces up to 50 liters of fresh water on a sunny day. In the emirate of Dubai, a desalination plant of 400 such modules is already being built.

Other interesting news:

▪ Eye instead of display

▪ Dust and water resistant smartphone LG Optimus GJ

▪ Hydrogen moped

▪ Adata Industrial Grade Solid State Drives ISSS332

▪ The Ultimate Weapon Against Insects

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the website Basics of First Medical Aid (BFA). Selection of articles

▪ article Augean stables. Popular expression

▪ article Which plant can copy the leaves of many other plants on the same shoot? Detailed answer

▪ article Bicycle computer. Travel Tips

▪ article Homemade wind generator. Encyclopedia of radio electronics and electrical engineering

▪ article Programmer Sim Card Reader SOLO GWR. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews