UMZCH supply voltage stabilizer. Modified scheme by V. Oreshkin (subscription to boards completed)

The bipolar power supply proposed by V. Oreshkin largely meets the mutually exclusive requirements for the UMZCH supply voltage stabilizer [1, 2]. This note describes a modified circuit that allows, by simple means, to increase the stabilization coefficient and reduce the output resistance while maintaining a small time constant of the aperiodic process. The modification came down to replacing ballast resistors in compensation stabilizers with current sources and taking into account the recommendations of Texas Instruments for constructing power supplies for UMZCH.

↑ Schematic diagram of the upgraded UMZCH power supply

The diagram of a bipolar power supply is shown in Fig. 1.

Fig.1. Bipolar power supply UMZCH

It consists of two galvanically unconnected rectifiers VD1, C1, C2, C5, C6, C9, C11, C13 and VD2, C3, C4, C7, C8, C10, C12, C14, two parametric stabilizers made on zener diodes VD3, VD4 and current sources on transistors VT5, VT6, and emitter followers on transistors VT1, VT3 and VT2, VT4. The stabilization coefficient is increased due to the supply of the reference voltage source of one stabilizer from the output voltage of the other and the use of current sources instead of resistors.

The rectifiers are assembled on diode bridges VD1, VD2, consisting of double Schottky diodes with a common cathode 16CTQ100. The diodes are connected in parallel.

Capacitors C1...C8; C9, C10 and RC - chains R9, C23 and R10, C24 are installed in accordance with the recommendations of Texas Instruments for the construction of power supplies for UMZCH [3].

To reduce noise, each zener diode VD3, VD4 is shunted by a pair of capacitors - oxide and film (C15, C17 and C16, C18, respectively).

Current sources on transistors VT5, VT6 contain parametric stabilizers HL1, C19, C21, R8 and HL2, C20, C22 in the bases of the transistors.

The current of each source is equal to: IVD4=(UHL1-UbeVT5)/R4=(1.76-0.56)/0.13=9.2 mA, IVD3=(UHL2-UbeVT6)/R7=9.2 mA.

Resistors R5, R6 reduce the power dissipated on the collectors of the current source transistors.

The collectors (cases) of powerful transistors VT1, VT2 are connected to the common wire of the power supply, which makes it possible to do without heat-conducting gaskets, thereby improving heat dissipation at high load currents.

To reduce the dynamic resistance of the power supply, its outputs are shunted with pairs of oxide-film capacitors (C25, C27 and C26, C28, respectively). Ballast resistors with green LEDs serve for indication (HL3, R11 and HL4, R12).

Resistor R2 is designed to trigger the bipolar stabilizer when the power is turned on.

The stabilizer has protection against short circuits in the load. If there is a short circuit in any arm, both stabilizers are switched off.

Main technical characteristics:

Stabilizer output voltage, V…. ±15 Maximum load current, A…. 20 Stabilization coefficient, not less than…. 1500 Output impedance, no more, Ohm.... 0.01 Voltage on the step-down windings of the power transformer, V.... 2×20

Connection diagram based on LM2940CT-12.0

The stabilizer body can be made of almost any material except wood. When using more than ten LEDs, it is recommended to attach an aluminum radiator to the stabilizer.

Maybe someone has tried it and will say that you can easily do without unnecessary troubles by directly connecting the LEDs. But in this case, the latter will be in unfavorable conditions most of the time, and therefore will not last long or will burn out altogether. But tuning expensive cars results in a fairly large sum.

As for the described schemes, their main advantage is simplicity. Manufacturing does not require any special skills or abilities. However, if the circuit is too complex, then assembling it with your own hands becomes unreasonable.

↑ Parts and analogues

The parts list (BOM) is below.
Details:

VD1, VD2 Schottky diode 16CTQ100 IR (100V, 16A) - 8 pcs., VD3, VD4 Zener diode BZX55C16 (16V, 0.4W), glass - 2 pcs., HL1, HL2 LED FYL-3014HD red d= 3 mm - 2 pcs., HL3, HL4 LED BL-B2141Q G green.d=3 - 2 pcs., VT1 Transistor KT827A (20A; 100V), housing TO-3 - 1 pc., VT2 Transistor KT825A (20A; 100V), case TO-3 - 1 pc., VT3 Transistor BD140, case TO-126 - 1 pc., VT4 Transistor BD139, case TO-126 - 1 pc., VT5 Transistor 2SA1013, case TO-92mod - 1 pc., VT6 Transistor 2SC2383, TO-92mod housing - 1 pc., R1, R3 Resistor -0.25-3.3 kOhm - 2 pcs., R2 Resistor -2-470 Ohm - 1 pc., R4, R7 Resistor -0.25- 130 Ohm - 2 pcs., R5, R6 Resistor -0.25-220 Ohm - 2 pcs., R8 Resistor -0.25-9.1 kOhm - 1 pc., R9, R10 CHIP resistor F2512-1 Ohm, 1W 1% - 2 pcs., R11, R12 Resistor -0.5-2.7 kOhm - 2 pcs., C1...C8 Capacitor 0.1/250V K73-17 - 8 pcs., C9, C10, C23, C24 Capacitor CHIP 1812 0.1µF/100V X7R 10% - 4 pcs., C11...C14 Capacitor 10000/50V 3035+85°C - 4 pcs., C15, C16 Capacitor 47/63V 0611+105°C - 2 pcs., C17 …C20 Capacitor 0.1/63V K73-17 - 4 pcs., C21, C22 Capacitor 47/16V 0511+105°C - 2 pcs., C25, C26 Capacitor 470/35V 0820+105°C - 2 pcs. C27, C28 Capacitor 1/63V K73-17 - 2 pcs., Radiator for VT1, VT2 Printed circuit board 150×70×2 mm - 1 pc.

The power supply uses MLT or foreign MF output resistors with the power indicated on the circuit diagram (Fig. 1).

Capacitors C1 - C8, C17 - C20, C27, C28 type K73-17, imported oxide capacitors. Capacitors C17 - C20 can be replaced with better results with CBB21/MPP made of metallized polypropylene (for example, 0.15 µF, 100 V from the Datagorsk fair). For C27, C28, 1 µF, 100 V (Suntan, polyester) is suitable.

Transistors KT825A and KT827A can be replaced with composite ones (KT819G + KT815G and KT818G + KT814G), while the emitter junctions of powerful transistors KT819G and KT818G must be shunted with resistors with a resistance of 100 - 150 Ohms. It is possible to replace high-power composite transistors with MJ11032 and MJ11033. With a maximum load current of 5 - 7 A, transistors TIP142 and TIP147, as well as BDW42G BDW47G, are suitable.

Transistors VT1, VT2 are mounted on a heat sink with a cooling surface area of 900 sq. cm without heat-insulating gaskets using heat-conducting paste ALSIL-3.

Instead of transistors BD139 and BD140, 2SC3502 and 2SA1380 or BF471 and BF472 are suitable. When replacing, be sure to check the pinout of the transistors.

Transistors VT5, VT6 type 2SA1013, 2SC2383 can be replaced with domestic KT502E, KT503E; KT6116, KT6117 or imported 2N5401, 2N5551; 2SA1145, 2SC2705 and others.

Schottky diodes in bridges VD1, VD2 are replaceable with MBR20200CTG (200 V, 10 A) with a common cathode, or with SR10100 (10 A, 100 V, TO-220-2). In the latter case, the printed circuit board will need to be adjusted.

For consumption currents of more than 2 A, it is necessary to equip the diodes with small radiators and (or) provide them with fan cooling.

With relatively low current consumption (up to 2 A) in diode bridges, you can use high-performance diodes HER505 (5 A, 1000 V), ultra-fast diodes SF56 (5 A, 400 V) or ultrafast STTH5R06FP (5 A, 600 V, TO-220- 2).

The maximum voltage stabilizer current is determined by the power transformer. For example, in the one shown in Fig. In diagram 1, transformer T1 type TPP321 provides a maximum current of no more than 4 A.

Do you need a voltage stabilizer for audio equipment?

A device intended for integration into a household electrical network to obtain specified parameters at the output is called a voltage stabilizer.

Reference. Since 2015, the Russian Federation has adopted a new power grid quality standard that corresponds to the European one. The normal voltage of the household network should now be 230 V (for industrial - 400 V). Frequency – 50 Hz. A deviation from the nominal value is allowed within 10%, that is, in the range of values 207-253 V.

Note: GOST 29322-2014 allows voltage to be supplied to consumers according to old standards - 220 V.

In fact, outdated equipment in many regions of the country and poor-quality wiring lead to significantly greater drawdowns, which could potentially result in breakdown or reduction in the service life of electrical appliances. How even a slight deterioration of the contacts in the distribution panel affects the voltage in the apartment is clearly shown in this video:

Currently, the energy company providing electricity supply services bears responsibility for damage to personal electrical equipment of citizens as a result of over- or under-voltage. However, you will have to seek compensation in court, and you will also have to prove that the actual voltage parameters are significantly higher/lower than normal. And this is a very complex process and not all victims are ready for litigation, which can last several months or even years.

Ultimately, people have to protect their equipment with the help of auxiliary devices - voltage stabilizers.

It is necessary to purchase a stabilizer that is 3-5 times greater than the total power of the electricity consumers connected to it. For example, a voltage regulator for a 150 W amplifier must be rated at least 450 W.

It is worth noting that a surge protector will not save devices from voltage sags; it can only slightly smooth out impulse noise present in the electrical network. But the stabilizer also performs the same function. This means that using a surge protector only makes sense when the user is confident that the electrical current parameters in his apartment or house comply with the standards.

You can read more about when a stabilizer can be replaced with a regular surge protector in this article.

↑ Printed circuit board

The parts of the device, except for the power transformer T1 and powerful transistors VT1, VT2, are mounted on a printed circuit board measuring 150x70 mm (see Fig. 2), made of foil fiberglass laminate.

Rice. 2. Placement of parts on the printed circuit board. The tracks are shown “in the light”, smd elements C9, C10, C23, C24, R9, R10 are installed on the side of the printed tracks

It is advisable to additionally solder the “power” tracks on the printed circuit board on top with tinned mounting wire with a diameter of 0.5 - 0.7 mm.

Device selection

When choosing a stabilizer, take into account the following characteristics:

Dimensions. The selected stabilizer must be compactly placed in its planned installation location with normal access.
View. Of the commercially available devices, the most reliable, compact and inexpensive are stabilizers based on small microcircuits.
Possibility of self-repair. Since even the most reliable devices fail, it is necessary to give preference to repairable stabilizers, radio components for which are commercially available in sufficient quantities and at an affordable price.
Reliability. The selected stabilizer must provide a constant voltage value without significant deviations from the range declared by their manufacturer.
Price. For the electrical system of a car, it is enough to purchase a device costing up to 200 rubles.

Also, when choosing a stabilizer, it is necessary to take into account customer reviews, which can be found on specialized forums and websites.

↑ Conclusions

The use of two separate rectifier bridges in the device, in my opinion, is a disadvantage, since compared to one diode bridge we have a twice as high voltage drop across the rectifier diodes, therefore, a lower maximum power.
In addition, the design with two diode bridges has large dimensions. The presence of two independently operating secondary windings of the transformer puts forward the additional requirement that their output voltages be equal.

The only advantage of a circuit with two rectifier bridges is that the maximum voltage on the bridge diode is two times lower, which can play a positive role when choosing Schottky rectifier diodes that have a low reverse voltage, no more than 45 - 200 V.

The described device can be used not only as a power source for UMZCH, but also as a powerful power source for automation devices.

Stabilizer for LEDs on the L7812 chip in cars

The current stabilizer for LEDs can be assembled on the basis of a 3-pin DC voltage regulator (L7812 series). The mounted device is perfect for powering both LED strips and individual light bulbs in a car.

Required components to assemble such a circuit:

chip L7812;
capacitor 330 uF 16 V;
capacitor 100 uF 16 V;
1 ampere rectifier diode (1N4001, for example, or a similar Schottky diode);
wires;
heat shrink 3 mm.

There can actually be many options.

↑ Sources mentioned

1. Oreshkin V. Power stabilizer UMZCH // Radio, 1987, No. 8, p.
31. 2. A modified version of a low-noise bipolar power supply (see comments 32-36 to the article.) 3. Recommendations from Texas Instruments for constructing power supplies for UMZCH. Thank you for your attention!

Linear stabilizer for LED lamps on cars

So, why do marker bulbs, LED bulbs or other LED bulbs that are in the car burn out so quickly, because they use a regular current-limiting resistor as a driver.

As a rule, LED lighting devices with a power of 10 W and above already use a high-quality pulse stabilizer - the driver does not suffer from such a disease, unlike large, cheap LED lamps.

First, these light bulbs begin to flicker, that is, these are already the first signs of crystal degradation, and then they simply burn out. On average, a simple LED light bulb has a lifespan of one year, sometimes less, sometimes a little more.

Why is this happening?

And this happens because this current-limiting resistor is calculated using a specialized formula (there are many such calculators online on the Internet) and is connected to the appropriate voltage.

Classic model

Classic stabilizers are a large class of devices assembled based on semiconductor parts such as bipolar transistors and zener diodes. Among them, the main function of maintaining the voltage at 12 V is performed by zener diodes - a type of diodes connected in reverse polarity (the plus of the power supply is connected to the cathode of such a semiconductor device, and the minus to the anode), operating in breakdown mode. The essence of how these semiconductor parts work is as follows:

When the voltage of the power source connected to the zener diode is less than 12 V, it is in the closed position and does not participate in adjusting this characteristic of the electric current.
When the threshold of 12 Volts is exceeded, the zener diode “opens” and maintains this value in the range specified by its characteristics.

If the voltage supplied to the zener diode exceeds that stated as the maximum by the manufacturer, the device very quickly fails due to the effect of thermal runaway.

In order for any model of zener diode to serve as long as possible, it is recommended to specify, according to its specification, the voltage range and current strength in which it should be operated.

Depending on the connection, there are two versions of the classic stabilizer: linear - the adjusting elements are connected in series with the load; parallel – voltage stabilizing devices are located parallel to the powered devices.