Diagrams of laboratory radio amateur power supplies. Diy power supply circuits

In most modern electronic devices, analog (transformer) power supplies are practically not used; they were replaced by pulse converters voltage. To understand why this happened, it is necessary to consider the design features, as well as the strengths and weaknesses of these devices. We will also talk about the purpose of the main components of impulse sources, we will give a simple example of implementation, which can be assembled by hand.

Design features and principle of operation

Of several ways to convert voltage to power electronic components, there are two that are most widespread:

1. Analog, the main element of which is a step-down transformer, in addition to the main function, it also provides galvanic isolation.
2. Impulse principle.

Let's see how these two options differ.

PSU based on power transformer

Let's consider a simplified block diagram of this device. As can be seen from the figure, a step-down transformer is installed at the input, with its help, the amplitude of the supply voltage is converted, for example, from 220 V we get 15 V. The next block is a rectifier, its task is to convert the sinusoidal current into a pulsed one (the harmonic is shown above the conventional image). For this purpose, rectifier semiconductor elements (diodes) are used, connected in a bridge circuit. Their operating principle can be found on our website.

The next block performs two functions: it smooths the voltage (for this purpose, a capacitor of the appropriate capacity is used) and stabilizes it. The latter is necessary so that the voltage "does not drop" with increasing load.

The given block diagram is greatly simplified, as a rule, a source of this type has an input filter and protective circuits, but this is not essential to explain the operation of the device.

All the disadvantages of the above option are directly or indirectly related to the main structural element - the transformer. First of all, its weight and dimensions limit miniaturization. In order not to be unfounded, we will give as an example a 220/12 V step-down transformer with a rated power of 250 W. The weight of such a unit is about 4 kilograms, dimensions are 125x124x89 mm. You can imagine how much a laptop charger based on it would weigh.

Secondly, the price of such devices is sometimes many times higher than the total cost of other components.

Pulse devices

As can be seen from the block diagram shown in Figure 3, the principle of operation of these devices differs significantly from analog converters, first of all, in the absence of an input step-down transformer.

Figure 3. Block diagram pulse unit nutrition

Consider the algorithm for the operation of such a source:

• Power is supplied to the surge protector, its task is to minimize network interference, both incoming and outgoing, arising from work.
• Further, the unit for converting the sinusoidal voltage into a pulsed constant and a smoothing filter comes into operation.
• At the next stage, an inverter is connected to the process, its task is related to the formation of rectangular high-frequency signals. Feedback to the inverter is carried out through the control unit.
• The next block is IT, it is necessary for automatic generator mode, voltage supply to circuits, protection, controller control, as well as load. In addition, IT is tasked with providing galvanic isolation between high and low voltage circuits.

Unlike a step-down transformer, the core of this device is made of ferrimagnetic materials, which contributes to the reliable transmission of RF signals, which can be in the range of 20-100 kHz. Characteristic feature IT lies in the fact that when it is connected, the inclusion of the beginning and end of the windings is critical. The small size of this device allows the manufacture of miniature devices, as an example, the electronic strapping (ballast) of an LED or energy-saving lamp.

• Then the output rectifier comes into operation, since it operates with a high-frequency voltage, the process requires high-speed semiconductor elements, therefore, Schottky diodes are used for this purpose.
• At the final phase, smoothing is performed on an advantageous filter, after which the voltage is applied to the load.

Now, as promised, we will consider the principle of operation of the main element of this device - the inverter.

How does an inverter work?

RF modulation can be done in three ways:

• frequency-pulse;
• phase-pulse;
• pulse-width.

In practice, the latter option is used. This is due to both the simplicity of execution and the fact that the PWM has a constant communication frequency, in contrast to the other two modulation methods. The block diagram describing the operation of the controller is shown below.

The device operation algorithm is as follows:

The master frequency generator generates a series of rectangular signals, the frequency of which corresponds to the reference. Based on this signal, a U P sawtooth shape is formed, which is fed to the input of the comparator K PWM. To the second input of this device, the signal U US is supplied, coming from the regulating amplifier. The signal generated by this amplifier corresponds to the proportional difference U P (reference voltage) and U RS (control signal from the feedback circuit). That is, the control signal U US, in fact, is the voltage of the mismatch with the level that depends both on the current at the load and on the voltage across it (U OUT).

This implementation method allows you to organize a closed circuit that allows you to control the output voltage, that is, in fact, we are talking about a linear-discrete functional unit. At its output, pulses are formed, with a duration depending on the difference between the reference and control signals. On its basis, a voltage is created to control the key transistor of the inverter.

The process of stabilizing the voltage at the output is carried out by monitoring its level; when it changes, the voltage of the control signal U RS changes proportionally, which leads to an increase or decrease in the duration between pulses.

As a result, the power of the secondary circuits changes, thereby stabilizing the output voltage.

To ensure safety, a galvanic isolation between the mains supply and the feedback... As a rule, optocouplers are used for this purpose.

Strengths and weaknesses of impulse sources

If we compare analog and pulse devices of the same power, then the latter will have the following advantages:

• Small size and weight, due to the absence of a low-frequency step-down transformer and control elements that require heat dissipation using large radiators. Through the use of high-frequency signal conversion technology, the capacitance of the capacitors used in the filters can be reduced, which allows the installation of smaller components.
• Higher efficiency, since only transients cause major losses, while in analog circuits, a lot of energy is constantly lost during electromagnetic conversion. The result speaks for itself, an increase in efficiency up to 95-98%.
• Lower cost due to the use of less powerful semiconductor elements.
• Wider input voltage range. This type of equipment is not picky about frequency and amplitude, therefore, it is allowed to connect to networks of different standards.
• Reliable protection against short-circuit, overload and other emergency situations.

The disadvantages of pulse technology include:

The presence of HF interference, this is a consequence of the operation of the high frequency converter. This factor requires the installation of a noise suppression filter. Unfortunately, its operation is not always efficient, which imposes some restrictions on the use of devices of this type in high-precision equipment.

Special requirements for the load, it should not be reduced or increased. As soon as the current level exceeds the upper or lower threshold, the output voltage characteristics begin to differ significantly from the standard ones. As a rule, manufacturers (recently even Chinese) provide for such situations and install appropriate protection in their products.

Scope of application

Almost all modern electronics are powered by blocks of this type, as an example:

We collect a pulse power supply unit with our own hands

Consider a simple power supply circuit using the above principle of operation.

Legend:

• Resistors: R1 - 100 Ohm, R2 - from 150 kOhm to 300 kOhm (selectable), R3 - 1 kOhm.
• Capacities: C1 and C2 - 0.01 μF x 630 V, C3 -22 μF x 450 V, C4 - 0.22 μF x 400 V, C5 - 6800 -15000 pF (selected), 012 μF, C6 - 10 μF x 50 V, C7 - 220 μF x 25 V, C8 - 22 μF x 25 V.
• Diodes: VD1-4 - КД258В, VD5 and VD7 - КД510А, VD6 - КС156А, VD8-11 - КД258А.
• Transistor VT1 - KT872A.
• Voltage stabilizer D1 - KR142 microcircuit with index ЕН5 - ЕН8 (depending on the required output voltage).
• Transformer T1 - a w-shaped ferrite core with dimensions of 5x5 is used. The primary winding is wound with 600 turns with a wire of Ø 0.1 mm, the secondary (terminals 3-4) contains 44 turns of Ø 0.25 mm, and the last one - 5 turns of Ø 0.1 mm.
• FU1 fuse - 0.25A.

The setting is reduced to the selection of R2 and C5 ratings, which provide excitation of the generator at an input voltage of 185-240 V.

The Vbus (+5 V) power bus of the USB port has very modest parameters in terms of the power consumed from it by an external device, and if you overdo it a little, you can burn the motherboard of a personal computer.

Using the proposed power supply circuit for the USB port, you can connect an external USB device that consumes more power to a computer or laptop.

The circuit is quite simple to make at home, with a minimum of scarce parts and settings. Stable in work.

A selection of circuits and designs of voltage converters made by hand.

Sooner or later, the radio amateur faces the problem of making a universal power supply that would be useful for all occasions. That is, it had sufficient power, reliability and adjustable over a wide range, moreover, it protected the load from excessive current consumption during tests and was not afraid of short circuits.

A selection of amateur radio circuits and designs of self-assembled voltage stabilizers.

The basis of the analog part is a differential amplifier assembled on an operational amplifier DA1. Its design is arbitrary. It all depends on the taste and abilities of the radio amateur

They can be connected to any radio amateur design with a voltage from 1 to 35 V and which is not afraid of high load currents, since current protection is introduced

I present to the attention of radio amateurs options for circuits and designs of simple and not very convenient and reliable laboratory power supplies for a home workshop. In the vastness of the Internet, you can find many schemes of laboratory power supplies, so these schemes do not pretend to be a masterpiece in any way, but are only designed to help radio amateurs, to equip their workshop or workplace a little. Also considered are options for converting computer ATX power supplies into laboratory

In terms of structure, the development offered to the attention of readers is not a remake: rectifier, - capacitor filter - half-bridge DC-to-AC converter (with a step-down transformer) - rectifiers - filters - stabilizers

It couldn't be easier, the circuit consists of a step-down transformer, a rectifier bridge on the D242, a voltage stabilizer and three KT827 transistors

The following radio amateur power supply protection schemes or chargers can work together with almost any source - mains, impulse and rechargeable batteries... The circuit implementation of these designs is relatively simple and can be repeated even by a novice radio amateur.

Several options for protection circuits against polarity reversal were considered, including a high-speed protection circuit on a field-effect transistor, which was tested in operation in the design of an automobile memory assembled by one's own hands from a computer power supply unit, and most importantly, it does not require almost any adjustment and adjustment.

This circuit of the current regulator is extremely simple and is made on an accessible element base and is easy to control.

I have implemented this idea. Rewind the highest power transformer (you have) so as to make eight secondary windings

You can use this power supply circuit to power digital devices. The circuit is supplemented with a voltmeter for monitoring and adjusting parameters

Voltage multiplier circuits can significantly reduce the weight and dimensions of the final device. To understand the operation of any voltage multiplier, consider the principles of building such devices. They can be roughly divided into symmetrical and asymmetrical.

With an output power of up to 220 watts, they took a battery from a car as a battery

It can be used to power a photomultiplier tube, but it can power a Geiger counter and other high voltage devices.

The role of the regulating element in the circuit is performed by powerful transistor, and the design is so simple that it can be repeated by any, even an inexperienced radio amateur, spending a minimum of time and money

This amateur radio design instantly reduces the power to zero on both arms, and thus has a trigger effect.

It can be used for any radio engineering with a voltage of 4.5-6 V, 9 V and a consumption current up to 500 mA

This PSU has a parametric current stabilizer and a compensation voltage regulator. Therefore, it is not afraid of a short circuit in the output, and the output transistor of the stabilizer practically cannot fail.

At the moment the power supply is switched on to the network, the AC voltage of the mains is rectified by a diode bridge, the ripple from which is smoothed out by a capacitive filter on capacitors. To reduce the amount of charge current passing through these capacitors, a resistor is added to the circuit. Then the rectified voltage is fed to a half-bridge inverter built on transistors.

Brief theoretical information about the construction and operation of uninterruptible power supplies, as well as the design of a homemade UPS

The electronic design discharges a powerful capacitor bank to the inductor at regular intervals, then to the next one, and so on along the chain

The mains voltage is fed through a fuse to the primary winding of the power transformer. From its secondary winding, we remove the already reduced voltage by 20 volts at a current of up to 25A. If desired, this transformer can be made with your own hands based on a power transformer from an old tube TV.

In the Russian hinterland, there are still frequent power outages, which seriously changes the settled way of life for the worse. It is very easy to solve the problem.

Sooner or later, any radio amateur will have a need for a powerful power supply unit both for checking various electronic components and blocks, and for connecting powerful amateur radio homemade products.

You can adjust the supply voltage level values \u200b\u200busing the regulators with pulse-width modulation. The advantage of this setting is that the output transistor operates in key mode and can only be in two states - open or closed, which eliminates overheating, which means the use of a large radiator and, as a consequence, reduces energy costs.

The rechargeable battery of any mobile computer needs to be charged periodically, but how can this be done while on vacation or fishing. It's very simple, you just need to assemble and use a regular car adapter for the car's on-board network, which is very easy and simple to assemble.

This converter with a bipolar power supply is perfect for powering an ULF of average power up to 150 watts, but if you change the keys to more powerful ones, you can get higher values.

To check and adjust powerful power supplies, a low-resistance regulated load with an allowable dissipation power of up to hundreds of watts is required. The use of variable resistances is not always realistic, mainly due to the power dissipation allowed.

If you have only one powerful transistor, then this is quite enough to assemble a simple power supply with an output voltage of 9V and with acceptable characteristics, in addition, we will consider constructions and more interesting ones within the framework of this article.

In rural areas, for the safe use of household appliances, a 220V single-phase voltage stabilizer is required, which, with a strong voltage drop in the network, maintains the rated output voltage of 220 volts at the output.

Car radio power supply

Then you can't do without an adjustable power supply. When assembling and debugging any device assembled by a radio amateur, the question always arises from what to power it. Here the choice is small, either a power supply unit or batteries (batteries). At one time, for these purposes, I purchased a Chinese adapter with an output voltage switch from 1.5 to 12 volts, but it turned out to be not entirely convenient in amateur radio practice. I began to look for a device circuit in which it would be possible to smoothly regulate the output voltage, and on one of the sites I found the following power supply circuit:

Adjustable power supply - electrical circuit

Part numbers in the diagram:

T1 Transformer with a voltage on the secondary winding of 12-14 volts.
VD1 KC405B
C1 2000 μFx25 volts
R1 470 Ohm
R2 10 kΩ
R3 1 kΩ
D1 D814D
VT1 KT315
VT2 KT817

I took some other parts in my power supply, specifically, I replaced the transistor kt817 on the kt805, simply because I already had it and, moreover, came right away with a radiator. It was possible to conveniently solder it to the terminals in order to connect it subsequently to the board by surface mounting. If there is a need to assemble such a power supply unit for high power, you need to take a transformer for 12-14 volts and, accordingly, a diode bridge also for high power. In this case, you will need to increase the area of \u200b\u200bthe radiator. I took, as indicated in the diagram, KC405B... If you want the voltage to be regulated not from 11.5 volts to zero, but higher, you need to select a zener diode for the desired voltage and transistors with a higher operating voltage. The transformer, of course, must also deliver a higher voltage on the secondary winding by at least 3-5 volts. Parts will have to be selected experimentally. I laid out a printed circuit board for this power supply:

In this device, the output voltage is regulated by rotating the knob of the variable resistor. The rheostat itself did not solder it into the board, but attached it to the top cover of the device and connected it to the board by hanging installation. On the board, the connected terminals of the variable resistor are designated as R2.1, R2.2, R2.3. If the voltage is regulated by turning the knob from left (minimum) to right (maximum), you need to swap the extreme terminals of the variable resistor. On the board, + and - indicate the plus and minus of the output. For accurate measurement with the tester, when setting the desired voltage, you need to add a 1 kOhm resistor between the plus and minus of the output. It is not indicated on the diagram, it is provided on my PCB. For those who still have stocks of old transistors, I can offer this option for a regulated power supply:

Regulated power supply on old parts - diagram

My power supply has a fuse, a rocker switch, and a power-on indicator on a neon lamp, all of which are hinged. To supply power to the assembled device, it is convenient to use insulated crocodile clips. They are connected to the power supply using laboratory clips, into which you can also plug the tester probes from above. This is convenient when you need to briefly supply power to the circuit, and "crocodiles" to connect nowhere, for example, during repairs, by touching the contacts on the board with the tips of the probes. Photo of the finished device in the figure below:

To the attention of radio amateurs is the development home laboratory power supply... The advantage of this PSU is that no additional windings are needed on the power transformer. The DA1 microcircuit operates with a unipolar supply. The output voltage is continuously adjustable from 0 to 30V. The power supply has a continuously adjustable current limitation.

The circuit design is simple and this power supply can be made by a novice radio amateur.

The rectified voltage + 38V, after the capacitor C1, is fed to the regulating transistor VT2 and the transistor VT1. A stabilizer is assembled on the transistor VT1, diode VD2, capacitor C2 and resistors R1, R2, R3, which is used to power the DA1 microcircuit. Diode VD2 is a three-pin, adjustable, parallel voltage regulator. At the output of the stabilizer, the resistor R2 sets a voltage of +6.5 volts, since the maximum supply voltage of the DA1 microcircuit is VDD \u003d 8 volts. On the operational amplifier DA1.1 TLC2272, the regulating part of the power supply voltage is assembled. Resistor R14 regulates the output voltage of the power supply. A reference voltage of 2.5 volts is applied to one of the contacts of the resistor R14. The accuracy of this voltage, within small limits, is set by selecting the resistor R9.

Through resistor R15, regulated by resistor R14, voltage is applied to input 3 of the operational amplifier DA1.1. Through this operational amplifier, the output voltage of the power supply is processed. Resistor R11 regulates the upper limit of the output voltage. As already mentioned, the DA1 microcircuit is powered by a unipolar voltage of 6.5V. And, nevertheless, at the output of the power supply, it was possible to obtain an output voltage equal to 0 V.

On the DA1.2 microcircuit, a power supply unit for current and short-circuit protection is built. Many such circuitry solutions for protection nodes have been described in various RL literature and therefore are not considered in detail.

The schematic diagram of the power supply is shown in Fig. 1.

The establishment of the power supply unit begins with the supply of voltage + 37 ... 38 V. On the capacitor C1. With the help of the resistor R2, a voltage of + 6.5V is set on the VT1 collector. The DA1 microcircuit is not inserted into the socket. After the output voltage on the leg 8 of the DA1 socket is set to + 6.5V, turn off the power and insert the microcircuit into the socket. Then they turn on the power and, if the voltage on the leg 8 DA1 differs from + 6.5V, adjust it. Resistor R14 must be brought to 0, i.e. in the lower position according to the scheme. After the power supply voltage of the microcircuit is set, a reference voltage of + 2.5V is set at the upper terminal of the variable resistor R14. If it differs from that indicated in the diagram, select the resistor R9. After that, the resistor R14 is transferred to the upper position and the upper limit of the output voltage of + 30V is set with the trimming resistor R11. The output lower voltage without resistor R16 is 3.3 mV, which does not affect the digital indicator reading and the readings are 0V. If a 1.3MΩ resistor is connected between legs 1 and 2 of the DA1.1 microcircuit, then the lower limit of the output voltage will decrease to 0.3 mV. Contact pads for resistor R16 are provided in the printed circuit board. Then a rheostatic resistance is connected to the load and the parameters of the protection unit are checked. If necessary, select resistors R6 and R8.
The following components can be used in this design.

VD2, VD3 - KPU2EH19, instead of the VT2 TIP147 transistor, you can use the domestic transistor KT825, VT3 - BD139, BD140, VT1 - any silicon low or medium power transistor with a voltage Uk of at least 50V. Trimmer resistors R2 and R11 from the SP5 series. The power transformer can be used for a power of 100 ... 160W. Resistor R16 with a TK characteristic of at least 30 ppm / Co and must be either wire or metal-foil type. The power supply is assembled on an 85 x 65 mm printed circuit board.

The reference voltage node on VD3 can be replaced with a node on the TLE2425 - 2.5v microcircuit. The input voltage of this microcircuit can vary from 4 to 40V. The output voltage is stable - 2.5V.

During setup, instead of the TLC2272 chip, the TLC2262 chip was experimentally used. All parameters remained the same, no deviations of the modes were observed.
When testing this design, the power supply of the microcircuit was not 6.5 V, but 5 V. In this case, the resistor R9 \u003d 1.6k. The power supply unit of the microcircuit was replaced by the unit shown in Fig. 5.

If the TLC2272 chip is not in a DIP-8 package, but in a SOIC-8 package, then you can proceed as follows without redoing the printed circuit board. A substrate is prepared from the insulated material - a rectangle measuring 20 x 5 mm. On this rectangle, with the "MOMENT" glue, it is glued with "paws to the top", i.e. upside down, microcircuit. The location of the microcircuit on the substrate is shown in Fig. 6.

After that, the resulting "sandwich" is glued, with the same glue, on the reverse side of the printed circuit board, after removing the DIP-8 socket (if it was soldered). The substrate with the microcircuit is glued, placing it evenly between the contact pads of the microcircuit on the printed circuit board. Leg 1 of the microcircuit should be opposite the contact pad belonging to leg 1 of the DA1 chip, or shifted slightly lower. After this operation, using flexible conductors and a soldering iron, we connect the legs of the microcircuit and the contact pads on the printed circuit board.

Several copies of these power supplies were collected by radio amateurs. They all started working immediately and showed the desired results.

When developing the design, an inexpensive base of parts was taken into account, a minimum of parts, ease of adjustment and handling, as well as output parameters that are most acceptable among radio amateurs.

List of radioelements

Designation	A type	Denomination	amount	Note	Score	My notebook
DA1	Operational amplifier	TLC2272	1			Into notepad
VT1	Bipolar transistor	2N2222A	1			Into notepad
VT2	Bipolar transistor	TIP147	1			Into notepad
VT3	Bipolar transistor	KT815G	1			Into notepad
VD1	Diode bridge	RS602	1			Into notepad
VD2, VD3	Voltage reference IC	TL431	2			Into notepad
VD4	Light-emitting diode	AL307B	1			Into notepad
VD5	Rectifier diode	1N4148	1			Into notepad
C1	Electrolytic capacitor	10000 uF 50 V	1			Into notepad
C2	Capacitor	510 pF	1			Into notepad
C3	Capacitor	3.3 nF	1			Into notepad
C4	Capacitor	100 nF	1			Into notepad
C5	Capacitor	150 nF	1			Into notepad
C6	Capacitor	470 nF	1			Into notepad
R1, R8	Resistor	3 kΩ	2			Into notepad
R2	Trimmer resistor	10 kΩ	1			Into notepad
R3	Resistor	4.53 k Ohm	1	1%		Into notepad
R4, R6	Resistor	4.7 k Ohm	2			Into notepad
R5, R17	Resistor	2 kΩ	2			Into notepad
R7	Variable resistor	4.7 k Ohm	1			Into notepad
R9	Resistor	2 kΩ	1	selection		Into notepad
R10	Resistor	510 Ohm	1			Into notepad
R11	Trimmer resistor	1.5 k Ohm	1			Into notepad
R12	Resistor	1 kΩ	1			Into notepad
R13, R15	Resistor	10 kΩ	2			Into notepad
R14	Variable resistor	2.2 k Ohm	1			Into notepad
R16	Resistor	1.3 MOhm	1			Into notepad
R18	Resistor	68 Ohm	1	0.5W		Into notepad
R19	Resistor	300 Ohm	1	0.5W		Into notepad
R20	Resistor	47 Ohm	1	0.5W		Into notepad
Rn	Resistor	0.2 ohm	1	wire		Into notepad
TP1	Transformer	100 - 160W	1			Into notepad
FU1	Fuse	2 A	1			Into notepad
SA1	Switch		1			Into notepad
	Scheme fig. 4
DA2	Stabilizer	TLE2425	1			Into notepad
VD5	Rectifier diode

This power supply has digital voltmeter, to monitor the output voltage and an ammeter, to monitor the load current. Before writing this article, the power supply was repeated by several radio amateurs and, there were no complaints about the work. The output voltage is continuously adjustable from 0 to 30V. The power supply has a continuously adjustable current limitation. The maximum output current was rated at 3A. The circuit design is simple and this power supply can be made by a novice radio amateur. In the presence of serviceable components, the construction starts immediately.

The power supply circuit is shown in the figure (high quality circuit is attached - see the list of files at the end of the article).

(ads2) Rectified voltage + 38V, after capacitor C1, fed to the regulating transistor VT2 and transistor VT1... On the transistor VT1, zener diode VD3, condenser C2 and resistors R1 assembled a stabilizer that is used to power the microcircuit DA1... At the output of the stabilizer, the voltage is + 33V. The power supply uses a microcircuit KIA324P, the power supply of which is + 36V. with a unipolar source. On a chip DA2.3, resistors R9, R10, R13, DA1 assembled a reference voltage source + 5V. This voltage is applied to the output voltage regulator (resistor R25) and resistor R7, the maximum protection current of the power supply. In this case, for a maximum protection current of 3A, it is 1.66V. On a chip DA2.4 assembled device protection unit for current, the sensor of which is a resistor R3... Resistor R4 the protection operation threshold is regulated. A two-color diode (red and green) from the company is used to indicate the protection operation threshold. Kingbright L-59SRSGC-CC with a common cathode lens diameter 5mm. If the device is working normally, the LED is green, with overcurrent or short circuit in the load, the LED is red. If there is no such model or similar, then instead of one LED, you can use two red and green LEDs, or with a color at the user's request.

Resistor R23 the upper limit of the output voltage of the power supply is set.

On a chip DA2.4, resistors R2-R4, R7, R14 assembly of protection and current limitation is assembled. Out (8) DA2.3 per resistor R7 a reference voltage of + 5V is supplied. Resistor R7 set the threshold for the maximum load current. As soon as there was an overload voltage from the output (14) DA2.4 through diode VD5 supplied to the non-inverting input of the microcircuit DA2.2 leg (3) transistor VT2 begins to lock and the voltage at the output of the power supply begins to decrease.

Establishing a power supply is reduced to the following operations.

When powering on the microcircuit DA2 should not be in the socket. Transistor VT1 should not heat up. Instead of a resistor R1 solder the trimmer resistor. A trimmer on the positive terminal C2 set the voltage to +33 volts. After that, the value of the variable resistor is measured with an ohmmeter and a constant resistor with the obtained value is soldered into the circuit (with the power off). We bring resistors R23 and R25 to the middle position, resistor R7 to the maximum level, and the resistor R4 to the minimum. We insert the microcircuit into the socket and turn on the power supply. Footed (4) DA2 there must be a voltage set at the output VT1... Outlet (8) DA2.3 there should be a voltage of + 5 volts. Then we measure the voltage at the output of the power supply and resistors R23 and R25 making sure it is regulated. Next stage. Displaying the resistor engine R25 to the maximum, and the trimming resistor R23 set the output voltage to +30 volts. Then we smoothly translate the resistor engine R25 to the minimum position and make sure that the voltage gradually decreases to 0 volts.

The voltage and current indicator is assembled on the controller ATtiny26L , the diagram of which is shown in the figure.

Terminals X1, X2, X4, X5, X6, X7 are connected to the same terminals of the power supply.

Setting up the display unit is reduced to installation with resistors R28 and R31 values \u200b\u200bof the output voltage and load current. Sum of resistors R28 and R29 should be 10kΩ, and the sum of the resistors R30 and R31 should be 22 com. The display unit initially shows the output voltage. By pressing the button SA1 the current is displayed, with the decimal point transferred to the first digit. For example: voltage indication is 22.7 V., and current indication is 2.58 A. The indication unit is connected to the power supply unit as follows:

The following figures show the printed circuit boards of the power supply and display unit.

The printed circuit boards of the power supply unit and the display unit are assembled on foil-coated one-sided fiberglass. The size of the power supply board is 120 x 60 mm, the display unit is 57 x 58 mm. Resistors MLT-0,125, electrolytic capacitors of the LP jamicon series and capacitors of the K-73 series are used in the design.

Indicators and an indication block of any glow color with a common anode.

Winding III and IV of the transformer T1 was originally designed to power the display unit on a microcircuit KR572PV2... I think connecting it to power the indication on the controller will not present any difficulty for a radio amateur.

Good luck in repeating the design.

P.S. Below I quote the words of one of the first, or more precisely, one of the first women to repeat this design:

“I happened to repeat many schemes of such devices, but I consider a new development by A.N. Patrina is quite successful, easily repeatable, and therefore, such a PSU will be useful to many radio amateurs. I myself have been using it for more than a year and a half - it works flawlessly. As for the indication of the output voltage and current, it is possible to apply both the digital version - the author's, and the arrow devices. It all depends on the desire and capabilities of radio amateurs. I wish you all success in repetition. "

Guseva Svetlana Mikhailovna, instrumentation and automation specialist

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File	Description	File size:
	Power supply PCB (high quality)	536 Kb
	Display unit printed circuit board (high quality)	318 Kb