Voltage and current regulator for kt825g. Electrical diagrams are free. Kt825 voltage regulator. For the scheme "Universal low voltage power supply"

The figure shows a diagram of a voltage doubler capable of providing a load current of up to 2 A. The converter is based on a pulse generator on a logic element QD1.1, covered by a circuit feedback R1C1R2, which sets the generation frequency. The pulse signals generated by it in antiphase are fed to the inputs of the logic elements DD1.3 and DD1.4. controlling powerful key transistors VT1 and VT2. To exclude the possibility of a short circuit of the power supply during the hour of their switching to the second inputs of elements DD1.3 (through the inverter DD1.2) and DD1.4 pulses are received, which are delayed by about a quarter of the period and are integrated by the R3C2 circuit. Due to this, the opening pulses: (negative with respect to the emitters polarity) on the bases of the transistors are spaced in time, and the through current through both transistors is excluded. If the transistor VT2 is open, the capacitor C3 is charged through the diode VD1 to stresses power supply. T160 current regulator circuit After half a period, the transistor VT1 opens, the capacitor C3 turns out to be connected in series with the source, and the capacitor C4 through the diode VD2 is charged almost to double stresses There is no domestic analogue of the CD4093- IC, however, in the described converter, you can use the K561TL1 IC, series transistors and diodes of the KD202 series. To reduce the level of ripple at maximum load currents, it is advisable to increase the capacitance of the capacitors C3 and C4 to 10 μF and, in addition, parallel to the capacitor C4, include a film or ceramic with a capacity of 0.1 ... 1 μF. Stephenson P. Cheap voltage doubler.- Wireless World ... 1983, Vol. 89. N 1573, p. 59. (Radio 2-85, p. 61) ...

For the diagram "Charger for 3-6-volt batteries"

The proposed charger is designed for charging with a stable current, first of all, miner's batteries, popularly referred to as "horse race". The self-discharge of these batteries is very high. And this means that after a month, moreover, without load, the same battery must be charged. The device is easy to modify for charging 12-volt batteries; it is also suitable (without modification) for charging 6-volt batteries. Scheme charger very simple (see figure). The rectifier and transformer are not shown in the diagram. The secondary winding provides a load current of more than 3 A at a voltage of 12 V. A bridge-type rectifier on D242A diodes, a filtering capacitor - 2000 μFx50 V (K50-6). Field-effect transistor KP302B (2P302B, KP302BM) with an initial drain current of 20-30 mA. Zener diode VD1 type D818 (D809). Transistor type with any letter. It can be replaced by a Darlington circuit, for example, KT818A and KT814A, etc. Phase-pulse power regulator for kmop Resistor R1, type MLT-0.25; resistor R2 of the PPZ-14 type, but it is completely suitable with a graphite coating; R3 - wire (nichrome - 0.056 Ohm / cm). Transistor VT2 is placed on a finned heat sink with a cooling surface of approximately 700 cm. Electrolytic capacitor C1 of any type. Structurally, the circuit is made on a printed circuit board located near the transistor VT2. To charge 12-volt batteries as well, the potential for a 6-volt AC increase should be considered. stresses on the secondary winding of the network transistor of the charger. This circuit was used in the same way as an attachment to the power supply (not a stabilized voltage source is also suitable). The advantage of this circuit is that it is not afraid of output short circuits, since it is actually a stable current generator. The magnitude of this current depends primarily on the offset that is set ...

For the "Transistor voltage regulator" circuit

In several issues of the magazine "Radioamator", circuits of network regulators on thyristors were printed, but such devices have a number of significant disadvantages limiting their capabilities. Firstly, they introduce quite noticeable interference into the electrical network, which often negatively affects the operation of televisions, radios, and tape recorders. Secondly, they can only be used to manage a load with an active resistance (light bulb, heating element) and cannot be used simultaneously with an inductive load (electric motor, transformer). Meanwhile, all these problems can be easily solved by assembling an electronic device in which the role of a regulating element would be played not by a thyristor, but by a powerful transistor. I propose this design, and it can be repeated by any, moreover, inexperienced radio amateur, spending a minimum of time and money. Transistor regulator stresses contains few radioelements, does not interfere with the electrical network and operates on a load with both active and inductive resistance. It can be used to adjust the brightness of the chandelier or table lamp, the heating temperature of the soldering iron or electric stove, electric fireplace, the speed of rotation of the electric motor, fan, electric drill or stresses on the transformer winding. ...

For the scheme "Universal low voltage power supply"

In practice, it is very common for food various devices required from 3 to 12 V. The described power supply unit allows you to obtain the following row: 3; 4.5 (5); nine; 12 V at load current up to 300 mA. There is a possibility of promptly changing the polarity of the output voltage. ...

For the "VOLTAGE CONVERTER" circuit

CONVERTER S. Sych225876, Brest region, Kobrin district, settlement Orekhovsky, Lenin st., 17 - 1. I offer a simple and reliable converter circuit stresses for the management of varicaps in various designs, which generates 20 V when supplied from 9 V. The variant of the converter with a voltage multiplier was chosen, since it is considered the most economical. In addition, it does not interfere with radio reception. A pulse generator close to rectangular is assembled on transistors VT1 and VT2. A voltage multiplier is assembled on diodes - VD1 ... VD4 and capacitors C2 ... C5. Resistor R5 and zener diodes VD5, VD6 form a parametric voltage regulator. The output capacitor C6 is an RF filter. The current consumption of the converter depends on stresses nutrition and the number of varicaps, as well as their type. It is desirable to enclose the device in a shield to reduce interference from the generator. Right assembled device works immediately and uncritically to the denominations of parts ...

For the diagram "Voltage converter 5 -> 230V"

Power supply Converter 5 -> 230 V Chips: DD1 - K155LA3 DD2 - K1554TM2 Transistors: VT1 - VT3 - KT698G, VT2 - VT4 - KT827B, VT5- KT863А Resistors: R1 - 910, R2 - 1k, R320 - 1k, R4t - 120 0.25 W, R6 - 500 0.25 W, R7 - R8 - 56 Ohm 2W, R9 - 1.5 kOm2W Diode VD5 - KC620A two in series Capacitors: C1 - 10H5 C2 - 22 μF x450V Transformer: T1 - two windings of 10 volts connected one 16A winding; for 220 volts current 1A, frequency 25kHz = Converter stresses 5 - 230V ...

For the diagram "Voltage regulator with indicator"

The device shown in Fig. 1 is designed for modulating control in low-power loads. With its help, it is possible to power the second additional radio engineering device from one power source, which has a supply of power. For example, a 15 ... 20 V power supply supplies the necessary circuit, and you need to additionally power a transistor receiver from it, which has a supply voltage lower (3 ... 9 V). The circuit is made on a field-effect epitaxial-planar transistor with a p-n-junction and an n-channel KP903. During the operation of the device, the property of the current-voltage characteristics of this transistor was used at different voltages between the gate and the source. The family of characteristics KP903A ... B is given in. Input supply voltage this device 15 ... 20 V. Resistor R2 of the PPB-ZA type with a nominal value of 150 Ohm. It can be used to set the required voltage in the load. The disadvantage of the regulator is the rise internal resistance devices when the operating voltage drops. Drozdov transceiver circuits Fig. 2 shows the indicator circuit stresses the above-described regulator, assembled on a field-effect transistor KP103. The device is designed to control stresses in load. The connection of this indicator to the regulator device is carried out according to the diagram below. Depending on the letter index KP103 of the indicator installed in the circuit (Fig. 2), we will fix (at the moment of ignition of the HL1 LED with an increase in the output voltage) the operating voltage in the load. The effect of fixing different voltages in the load is obtained as a result of the fact that KP103 channel transistors have different stresses cutoffs depending on the letter index, for example, for the KP103E transistor it is 0.4-1.5 V, for the KP103Zh - 0.5-2.2 V, for the KP103I - 0.8-3 V, etc. By installing a transistor with the required letter ...

For the diagram "Converter of DC voltage 12 V to AC 220 V"

DC 12V to AC 220V converter Anton Stoilov stresses 12V AC 220V, which when connected to car battery with a capacity of 44 Ah, it can power a 100-watt load for 2-3 hours. It consists of a master oscillator on symmetrical multivibrator VT1, VT2, loaded on powerful paraphase switches VT3-VT8, switching the current in the primary winding of the step-up transformer TV. VD3 and VD4 protect powerful transistors VT7 and VT8 from overvoltage during no-load operation. The transformer is made on a magnetic circuit Ш36х36, the windings W1 and W1 "have 28 turns of PEL 2.1, and W2 has 600 turns of PEL 0.59, and W2 is first wound, and on top of it with a double wire (with the task of achieving the symmetry of the semi-windings) W1. When adjusting with the RP1 trimmer, minimal distortion of the output shape is achieved. stresses"Radio Television Electronics" N6 / 98, p. 12.13 ....

In the practice of a radio amateur, a situation often arises when it is necessary to track the readings of one or another parameter. I propose a diagram of an indicator LED "ruler". Depending on the input, more or less LEDs are lit, arranged in a line (one after the other). stresses- 4 ... 12V, i.e. with an input voltage of 4 V, only one (first) LED will be lit, and with an input voltage of 4 V, the entire line will be lit. The possibilities of the circuit can be easily expanded. To monitor the alternating voltage, it is enough to install a diode bridge of low-power diodes before resistor R1. The supply voltage can be varied from 5 to 15 V by selecting the resistors R2 ... R8, respectively. The brightness of the LEDs mainly depends on the power supply of the circuit, while the input characteristics of the circuit remain practically unchanged. Wiring diagram of the Azovets pump In order for the brightness of the LEDs to be the same, the resistors should be selected as follows: where Ik max is the collector current VT1, mA; R3 = 2R2; R4 = 3R2; R5 = 4R2; R6 = 5R2; R7 = 6R2; R8 = 7R2. Thus, when using the KT312A transistor (lK max = 30 mA) R2 = 33 Ohm. Resistor R1 enters the divider stresses and regulates the operating mode of the transistor VT1. Diodes VD1 ... VD7 can be changed to KD103A, KD105, D220, LEDs HL1 ... HL8 - to AL102. Resistor R9 limits the base current of the transistor VT1 and prevents the latter from failing when a high voltage enters the input of the circuit. A. KASHKAROV, St. Petersburg ....

Hello dear readers. There are many circuits where the wonderful powerful composite transistors KT827 are used with great success and, naturally, sometimes it becomes necessary to replace them. The code at hand for these transistors is not found, then we begin to think about their possible analogues.

I did not find complete analogues among foreign-made products, although there are many proposals and statements on the Internet about replacing these transistors with TIP142. But these transistors have a maximum collector current of 10A, for 827 it is 20A, although their powers are the same and equal to 125W. The 827 has a maximum collector-emitter saturation voltage of two volts, and the TIP142 has 3V, which means that in a pulsed mode, when the transistor is in saturation, at a collector current of 10A, our transistor will produce 20W, and in the bourgeois - 30W , so you will have to increase the size of the radiator.

A good replacement can be the KT8105A transistor, see the data in the plate. With a collector current of 10A, the saturation voltage of this transistor is not more than 2V. It's good.

In the absence of all these replacements, I always collect an approximate analogue on discrete elements. The transistor circuits and their appearance are shown in photo 1.

I usually collect by hanging installation, one of possible options shown in photo 2.

Depending on the required parameters of the composite transistor, you can select transistors for replacement. The diagram shows D223A diodes, I usually use KD521 or KD522.

In photo 3, the assembled composite transistor operates at a load at a temperature of 90 degrees. The current through the transistor is this case is equal to 4A, and the voltage drop across it is 5 volts, which corresponds to the allocated thermal power of 20W. Usually I arrange this procedure for semiconductors for two or three hours. For silicon, this is not at all scary. Of course, for such a transistor to work on a given radiator inside the device case, additional airflow will be required.

To select transistors, I give a table with parameters.

Due to their high efficiency, switching voltage stabilizers are obtained in recent times more and more widespread, although they are usually more complex than traditional ones and contain a greater number of elements. So, for example, a simple pulse stabilizer (Fig.5.6) with an output voltage lower than the input voltage can be assembled on only three transistors, two of which (VT1, VT2) form a key regulating element, and the third (VT3) is an error amplifier.

The device operates in a self-oscillating mode. The voltage of positive feedback from the collector of the transistor VT2 (it is composite) through the capacitor C2 enters the base circuit of the transistor VT1. Transistor VT2 periodically opens until saturation with current flowing through resistor R2. Since the base current transfer ratio of this transistor is very high, it saturates at a relatively low base current. This makes it possible to choose the resistance of the resistor R2 rather large and, therefore, to increase the transfer coefficient of the regulating element.

The voltage between the collector and the saturated emitter) of the transistor VT1 is less than the opening voltage of the transistor VT2 (in a composite transistor, as you know, between the terminals of the base and the emitter, two pn junction), therefore, when the transistor VT1 is open, VT2 is reliably closed.

The element of comparison and the amplifier of the error signal is a cascade on the VT3 transistor. Its emitter is connected to the reference voltage source - the Zener diode VD2, and the base is connected to the output voltage divider R5 ... R7.

In pulse stabilizers, the regulating element operates in a key mode, therefore the output voltage is regulated by changing the duty cycle of the key. In the device under consideration, the transistor VT1 controls the opening and closing of the transistor VT2 according to the signal of the transistor VT3. At the moments when the transistor VT2 is open, in the choke L1, due to the flow of the load current, it is stored electromagnetic energy... After the transistor turns off, the stored energy is transferred to the load through the VD1 diode.

Despite its simplicity, the stabilizer has a fairly high efficiency. So, with an input voltage of 24 V, an output voltage of 15 V and a load current of 1 A, the measured efficiency was 84%.

Choke L1 is wound on a K26x16x12' ferrite ring with a magnetic permeability of 100 with a wire with a diameter of 0.63 mm and contains 100 turns. The inductance of the choke at a bias current of 1 A is about 1 mH. The characteristics of the stabilizer are largely determined by the parameters of the transistor VT2 and the diode VD1, the speed of which should be as possible as possible. In the stabilizer, you can use transistors KT825G (VT2), KT313B, KT3107B (VT1), KT315B, (VT3), diode KD213 (VD1) and Zener diode KS168A (VD2).

The source is convenient for powering the electronic devices and charging rechargeable batteries... The stabilizer is built according to a compensation circuit, which is characterized by a low level of output voltage ripple and, despite the low compared to pulse stabilizers The efficiency fully complies with the requirements for a laboratory power supply.

The schematic 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 SZ-C6, a voltage stabilizer DA1 with an external powerful regulating transistor VT1, a current stabilizer assembled on an OS DA2 and an auxiliary bipolar power supply for it, an output voltage / current meter load PA1 with switch SA2 "Voltage / Current".

In the voltage stabilization mode at the output of the op-amp DA2 high level, LED HL1 and diode VD9 are closed. Stabilizer DA1 and transistor VT1 work 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 a linear mode, turning on and unloading the stabilizer DA1. The output voltage is set by 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 rises above the value set by the variable resistor R8, the voltage at the op-amp output 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.

The auxiliary low-power bipolar power supply of the op-amp DA2 is assembled on two half-wave rectifiers on VD1, VD2 with parametric stabilizers VD7R1, VD8R2. Their common point connected to the output of an adjustable stabilizer DA1. Such a scheme was chosen to minimize the number of turns of the auxiliary winding III, which must be additionally wound on the mains transformer T1.

Most of the unit's parts are placed on a printed circuit board made of 1 mm thick glass fiber foil on one side. A drawing of the printed circuit board is shown in Fig. 2. Resistor R9 is composed of two resistors of 1.5 0m with a power of 1 W. Transistor VT1 is fixed on a pin heatsink with external dimensions 130x80x20 mm, which is the back wall of the source casing. Transformer T1 must have an overall power of 40 ... 50 W. The voltage (under load) of winding II should be about 25 V, and winding III - 12 V.

With the element ratings 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 by a selection of R6R10 divider resistors. The upper current limit can also be raised by reducing the resistance of the shunt R9, but at the same time it is necessary 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 op-amp DA2 are mounted and tested, then everything else, except DA2. After making sure that the adjustable voltage stabilizer is working, the DA2 op-amp is soldered and the adjustable current stabilizer is checked 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 available microammeter. In my source, an M42305 microammeter with a full deflection current of the arrow of 50 μA is used.

Capacitor C13 in accordance with the recommendations of the manufacturer of the stabilizer K142EN12A, it is desirable to use tantalum, for example, K52-2 (ETO-1). The KT837E transistor can be replaced with 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 are suitable (correction of the printed circuit board conductor pattern may be required). The K142EN12A stabilizer can be replaced with the imported LM317T.

If it is necessary that the output voltage can be adjusted from zero, you need to add a galvanically isolated additional voltage stabilizer of 1.25 V to the source (it can also be assembled on K142EN12A) and connect it with a plus to the common wire, and a minus to the right terminal connected together and the slider of the variable resistor R10, previously disconnected from the common wire.

Radio No. 10, 2006

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