Schemes of amateur radio developments for power supplies. Radio amateur power supply - Power supplies (laboratory) - Power supplies. Power supply diagram

Simple and reliable block With your own hands, at the current level of development of the element base of radio-electronic components, you can do it very quickly and easily. In this case, knowledge of electronics and electrical engineering is not required. high level. You will soon see this.

Making your first power source is quite an interesting and memorable event. Therefore, an important criterion here is the simplicity of the circuit, so that after assembly it immediately works without any additional settings or adjustments.

It should be noted that almost every electronic, electrical device or the device needs power. The difference lies only in the basic parameters - the magnitude of voltage and current, the product of which gives power.

Making a power supply with your own hands is a very good first experience for novice electronics engineers, since it allows you to feel (not on yourself) the different magnitudes of currents flowing in devices.

The modern power supply market is divided into two categories: transformer-based and transformerless. The first ones are quite easy to manufacture for beginner radio amateurs. The second undeniable advantage is the relatively low level electromagnetic radiation, and accordingly interference. A significant drawback by modern standards is the significant weight and dimensions caused by the presence of a transformer - the heaviest and most bulky element in the circuit.

Transformerless power supplies do not have the last drawback due to the absence of a transformer. Or rather, it is there, but not in the classical presentation, but works with high-frequency voltage, which makes it possible to reduce the number of turns and the size of the magnetic circuit. As a result, the overall dimensions of the transformer are reduced. High frequency is formed by semiconductor switches, in the process of switching on and off according to a given algorithm. As a result, strong electromagnetic interference occurs, so such sources must be shielded.

We will be assembling a transformer power supply that will never lose its relevance, since it is still used in audio equipment high class, due to the minimal level of noise generated, which is very important for obtaining high-quality sound.

Design and principle of operation of the power supply

The desire to obtain a finished device as compact as possible led to the emergence of various microcircuits, inside of which there are hundreds, thousands and millions of individual electronic elements. Therefore, almost any electronic device contains a microcircuit whose standard power supply is 3.3 V or 5 V. Auxiliary elements Can be powered from 9V to 12V DC. However, we know well that the outlet AC voltage 220 V frequency 50 Hz. If it is applied directly to a microcircuit or any other low-voltage element, they will instantly fail.

From here it becomes clear that the main task of the mains power supply (PSU) is to reduce the voltage to an acceptable level, as well as convert (rectify) it from AC to DC. In addition, its level must remain constant regardless of fluctuations in the input (in the socket). Otherwise, the device will be unstable. Therefore, one more most important function BP is voltage level stabilization.

In general, the structure of the power supply consists of a transformer, rectifier, filter and stabilizer.

In addition to the main components, a number of auxiliary components are also used, for example, indicator LEDs that signal the presence of supplied voltage. And if the power supply provides for its adjustment, then naturally there will be a voltmeter, and possibly also an ammeter.

Transformer

In this circuit, a transformer is used to reduce the voltage in a 220 V outlet to the required level, most often 5 V, 9 V, 12 V or 15 V. At the same time, galvanic isolation of high-voltage and low-voltage circuits is also carried out. Therefore, in any emergency situations, the voltage on the electronic device will not exceed the value of the secondary winding. Galvanic isolation also increases the safety of operating personnel. In case of touching the device, a person will not fall under the high potential of 220 V.

The design of the transformer is quite simple. It consists of a core that performs the function of a magnetic circuit, which is made of thin plates that conduct magnetic flux well, separated by a dielectric, which is a non-conductive varnish.

At least two windings are wound on the core rod. One is primary (also called network) - 220 V is supplied to it, and the second is secondary - reduced voltage is removed from it.

The operating principle of the transformer is as follows. If voltage is applied to the mains winding, then, since it is closed, alternating current will begin to flow through it. An alternating magnetic field arises around this current, which collects in the core and flows through it in the form magnetic flux. Since there is another winding on the core - the secondary one, under the influence of an alternating magnetic flux it appears electromotive force(EMF). When this winding is shorted to a load, alternating current will flow through it.

Radio amateurs in their practice most often use two types of transformers, which mainly differ in the type of core - armored and toroidal. The latter is more convenient to use because you can easily wind it up required quantity turns, thereby obtaining the required secondary voltage, which is directly proportional to the number of turns.

The main parameters for us are two parameters of the transformer - voltage and current of the secondary winding. We will take the current value to be 1 A, since we will use zener diodes for the same value. About that a little further.

We continue to assemble the power supply with our own hands. And the next order element in the circuit is a diode bridge, also known as a semiconductor or diode rectifier. It is designed to convert the alternating voltage of the secondary winding of the transformer into direct voltage, or more precisely, into rectified pulsating voltage. This is where the name “rectifier” comes from.

There are various rectification circuits, but the bridge circuit is the most widely used. The principle of its operation is as follows. In the first half-cycle of the alternating voltage, current flows along the path through the diode VD1, resistor R1 and LED VD5. Next, the current returns to the winding through open VD2.

At this moment, applied to diodes VD3 and VD4 reverse voltage, therefore they are locked and no current flows through them (in fact, it flows only at the moment of switching, but this can be neglected).

In the next half-cycle, when the current in the secondary winding changes its direction, the opposite will happen: VD1 and VD2 will close, and VD3 and VD4 will open. In this case, the direction of current flow through resistor R1 and LED VD5 will remain the same.

A diode bridge can be soldered from four diodes connected according to the diagram above. Or you can buy it ready-made. They come in horizontal and vertical versions in different housings. But in any case, they have four conclusions. The two terminals are supplied with alternating voltage, they are designated by the sign “~”, both are the same length and are the shortest.

The rectified voltage is removed from the other two terminals. They are designated “+” and “-”. The “+” pin has the longest length among the others. And on some buildings there is a bevel near it.

Capacitor filter

After the diode bridge, the voltage has a pulsating nature and is still unsuitable for powering microcircuits, and especially microcontrollers, which are very sensitive to various kinds of voltage drops. Therefore it needs to be smoothed out. To do this, you can use a choke or a capacitor. In the circuit under consideration, it is enough to use a capacitor. However, it must have a large capacity, so it should be used electrolytic capacitor. Such capacitors often have polarity, so it must be observed when connecting to the circuit.

The negative terminal is shorter than the positive one and a “-” sign is applied to the body near the first one.

Voltage regulator L.M. 7805, L.M. 7809, L.M. 7812

You probably noticed that the voltage in the outlet is not equal to 220 V, but varies within certain limits. This is especially noticeable when connecting a powerful load. If not used special measures, then it will change in a proportional range at the output of the power supply. However, such vibrations are extremely undesirable and sometimes unacceptable for many electronic elements. Therefore, the voltage after the capacitor filter must be stabilized. Depending on the parameters of the powered device, two stabilization options are used. In the first case, a zener diode is used, and in the second, an integrated voltage stabilizer is used. Let's consider the application of the latter.

In amateur radio practice, voltage stabilizers of the LM78xx and LM79xx series are widely used. Two letters indicate the manufacturer. Therefore, instead of LM there may be other letters, for example CM. The marking consists of four numbers. The first two - 78 or 79 - mean positive or negative voltage, respectively. The last two digits, in this case instead of two X's: xx, indicate the value of the output U. For example, if the position of two X's is 12, then this stabilizer produces 12 V; 08 – 8 V, etc.

For example, let's decipher the following markings:

LM7805 → 5V positive voltage

LM7912 → 12 V negative U

Integrated stabilizers have three outputs: input, common and output; designed for current 1A.

If the output U significantly exceeds the input and the maximum current consumption is 1 A, then the stabilizer gets very hot, so it should be installed on a radiator. The design of the case provides for this possibility.

If the load current is much lower than the limit, then you don’t have to install a radiator.

The classic design of the power supply circuit includes: a network transformer, a diode bridge, a capacitor filter, a stabilizer and an LED. The latter acts as an indicator and is connected through a current-limiting resistor.

Since in this circuit the current-limiting element is the LM7805 stabilizer (allowable value 1 A), all other components must be rated for a current of at least 1 A. Therefore, the secondary winding of the transformer is selected for a current of one ampere. Its voltage should not be lower than the stabilized value. And for good reason, it should be chosen from such considerations that after rectification and smoothing, U should be 2 - 3 V higher than the stabilized one, i.e. A couple of volts more than its output value should be supplied to the input of the stabilizer. Otherwise it will not work correctly. For example, for LM7805 input U = 7 - 8 V; for LM7805 → 15 V. However, it should be taken into account that if the value of U is too high, the microcircuit will heat up very much, since the “excess” voltage is extinguished at its internal resistance.

The diode bridge can be made from 1N4007 type diodes, or take a ready-made one for a current of at least 1 A.

Smoothing capacitor C1 should have a large capacity of 100 - 1000 µF and U = 16 V.

Capacitors C2 and C3 are designed to smooth out high-frequency ripple that occurs when the LM7805 operates. They are installed for greater reliability and are recommendations from manufacturers of stabilizers of similar types. The circuit also works normally without such capacitors, but since they cost practically nothing, it is better to install them.

DIY power supply for 78 L 05, 78 L 12, 79 L 05, 79 L 08

Often it is necessary to power only one or a pair of microcircuits or low-power transistors. In this case, it is not rational to use a powerful power supply. That's why the best option stabilizers of the 78L05, 78L12, 79L05, 79L08 series, etc. will be used. They are designed for a maximum current of 100 mA = 0.1 A, but are very compact and no larger in size than a regular transistor, and also do not require installation on a radiator.

The markings and connection diagram are similar to the LM series discussed above, only the location of the pins differs.

For example, the connection diagram for the 78L05 stabilizer is shown. It is also suitable for LM7805.

The connection diagram for negative voltage stabilizers is shown below. The input is -8 V, and the output is -5 V.

As you can see, making a power supply with your own hands is very simple. Any voltage can be obtained by installing an appropriate stabilizer. You should also remember the transformer parameters. Next we will look at how to make a power supply with voltage regulation.

Power part assembled using a bridge circuit using powerful IGBT transistors B1-B4 (there is no EMI filter on the diagram). D1-D4 - diode bridge. R6 and RS1 - diagram smooth start, provides a gradual charge of filter capacitor C3, eliminating current surge. C5, R7, R8 - PWM controller startup circuit. C2, R10 - damping chain. LR1-LR2, D5-D8, R9, WR - output current adjustment.

List of radio components of the power unit:

Circuit breakers
F1-5A

IGBT transistors
B1, B2, B3, B4 - G20N60

Diodes
D1, D2, D3, D6 - 6A10 (6A 1000V)
D7, D8, D9, D10 - 4148

Capacitors
C1 - 2.2uF 630V
C2 - 332 630V (3300pF, 3.3nF, 0.0033 uF)
C3 - 600uF 400V, electrolytic
C4 - 220uF 400V, electrolytic
C5 - 22uF 400V, electrolytic
C6 - 104 (100nF, 0.1uF)

Resistors
RB1, RB2, RB3, RB4 - 3.3K
R5 - 10K
R6 -100/10W
R7 - 10K/2W
R8 - 120K/2W
R9 - 150
R10 - 51/10W
RW - 510, trimmer

Relay
RS1- 12V 10A

LR1, LR2 - current transformer
ferrite ring 20*12*6 2000NM, secondary winding LR2 - 100 turns of wire 0.12-0.15 mm2, primary winding LR1—a jumper passed through the ring.

PM1 PWM controller block assembled on microcircuits TL494 and IR2181, capable of controlling powerful IGBT or MOSFET transistors with a current of up to 60A. Using this block, it is possible to build a powerful bridge power supply from 1 to 3 kW.

List of radio components of the PWM controller:

Microcircuits
TL494
IR2181 - 2 pcs.

Diodes
UF 407 - 2 pcs.
Zener 18V

Capacitors
224 (200n, 0.22uF) - 3pcs
103 (10n, 0.01uF) - 2 pcs.
102 (1000pF, 1n) - 1 pc.
100uF*35V - 1 pc.
100uF*16V - 1 pc.

Resistors
10 - 4pcs.
51 - 1 piece.
1K - 4 pcs.
2K - 5 pcs.
10K - 1 piece
15K - 1 piece.
82K - 2 pcs.

Secondary circuits with unipolar power supply and power transformer

The power transformer is made on an EE55 core, material N87. Primary winding N1 - 0.35*6=35 turns, N2,N3 - 0.55*10=6+6 turns, N4-0.55=3 turns, N5 - 0.55=2 turns.

Choke L1 is made on an EE55 core, material N87 0.55 * 20 = 9 vics

Stabilizer V1 - 12V, power supply for fan and relay Rs1. Stabilizer V2 - 18V, power supply PWM controller. WR1 - output voltage adjustment.

Secondary circuits with bipolar power supply and power transformer

The power transformer is made on an EE55 core, material N87 (when calculated by the Lite-CalcIT program, core size: E 42/21/20 N87). Primary winding N1 - 0.35*6=35 turns, N2,N3 - 0.55*4=9+9 turns, N4-0.55=3 turns, N5 - 0.55=2 turns.

Choke L1a L1b is made on an EE55 core, material N87 0.55*10=9+9 vics (opposite winding direction).

Stabilizer V1 - 12V, power supply for fan and relay Rs1. Stabilizer V2 - 18V, power supply PWM controller. WR1 - output voltage adjustment.

Printed circuit board of the control unit....>>>

Good day, forum users and site guests. Radio circuits! Wanting to put together a decent, but not too expensive and cool power supply, so that it has everything and it doesn’t cost anything. In the end, I chose the best, in my opinion, circuit with current and voltage regulation, which consists of only five transistors, not counting a couple of dozen resistors and capacitors. Nevertheless, it works reliably and is highly repeatable. This scheme has already been reviewed on the site, but with the help of colleagues we managed to improve it somewhat.

I assembled this circuit in its original form and encountered one unpleasant problem. When adjusting the current, I can’t set it to 0.1 A - at least 1.5 A at R6 0.22 Ohm. When I increased the resistance of R6 to 1.2 Ohms, the current during a short circuit turned out to be at least 0.5 A. But now R6 began to heat up quickly and strongly. Then I used a small modification and got a much wider current regulation. Approximately 16 mA to maximum. You can also make it from 120 mA if you transfer the end of the resistor R8 to the T4 base. The bottom line is that before the resistor voltage drops, a drop is added B-E transition and this additional voltage allows you to open T5 earlier, and as a result, limit the current earlier.

Based on this proposal, I conducted successful tests and eventually received a simple laboratory power supply. I am posting a photo of my laboratory power supply with three outputs, where:

• 1-output 0-22v
• 2-output 0-22v
• 3-output +/- 16V

Also, in addition to the output voltage regulation board, the device was supplemented with a power filter board with a fuse block. What happened in the end - see below.

Sooner or later, a radio amateur faces the problem of making a universal power supply unit (PSU) that would be useful for “all occasions.” That is, it had sufficient power, reliability, and a widely adjustable output voltage; moreover, it protected the load from “excessive consumption” of current during testing and was not afraid short circuits.

It is proposed, in the author's opinion, that the power supply that best satisfies these conditions is simple enough to repeat, providing a stabilized voltage of 1.5-24 V with an output current of up to ZA. In addition, it can operate in current source mode with the ability to smoothly adjust the stabilization current within 10-100 mA or with fixed current values ​​of 0.1 A, 1 A, 3 A.

Let's look at the diagram power supply(see figure). Its basis is a traditional voltage stabilizer circuit, the “heart” is the KR142EN12 microcircuit, which is currently available to a wide range of radio amateurs. A fairly powerful unified incandescent transformer TN-56 was chosen as the power transformer, which has four secondary windings with a permissible current of 3.4 A and a voltage of each 6.3 V. Depending on the required output voltage, switch SA2 connects two, three or four series-connected windings This is necessary to reduce the power dissipated on the control element, and, consequently, increase Device efficiency and relief temperature regime. Indeed, in the most unfavorable mode, with the maximum difference between the input and output voltages (of course, if the output voltage corresponds to the range specified by switch SA2) and the maximum current FOR, the power dissipated on the control element will be: Ppacc.max = (Uвx.max-2Uvd- Uout.min)*Imax (1) Rdis.max = (12.6-2*0.7-1.5)*3 = 29.1 W, where Uin.max is the maximum input effective voltage of this range; Uout.min - minimum output voltage of this range; Uvd is the voltage drop across the rectifier bridge diode. It is easy to check that without dividing the output voltage into ranges, the power dissipated by the control element reaches 70 W.

The alternating voltage is rectified by the diode bridge VD1-VD4 and smoothed by capacitor C5. Fuse FU2 protects the transformer when the rectifier diodes fail. Transistors VT1, VT2 serve to increase the output current of the power supply unit and facilitate the operation of the integrated stabilizer DA1. Resistor R1 sets the current through DA1, opening VT2:
IDA1 = Ubevt2/R1 = 0.7/51 = 0.014 A, (2)
where Ubevt2 is the opening voltage of the emitter-base of transistor VT2. At a current of 14 mA, the DA1 chip can operate without a heatsink. To increase the stability of the output voltage, the control voltage is removed from the line of resistors R2-R4 connected to the output of the microcircuit and supplied to the “control” pin 01 DA1 through the decoupling diode VD6. The output voltage is adjusted by resistors: R4 - “COARSE” and R3 - “FINE”. The current stabilizer is made of DA1, current-setting resistors R5-R9 and decoupling diode VD7. The selection of the required discrete stabilization current is carried out by switch SA3. In addition, at the “10-100 mA” limit, it is possible to smoothly regulate the current using resistor R9. If necessary, you can change the stabilization current by changing the values ​​of the setting resistors using the formula:
R = 1.35/Istab, (3)
where R is the resistance of the current-setting resistor, Ohm; Istab - stabilization current, A. The power of current-setting resistors is determined by the formula:
Р = I*I*R, (4)
where I is the range stabilization current; R is the resistance of the resistor. In reality, the power of the current-setting resistors has been deliberately increased for reasons of reliability. So resistor R8 type C5-16V is selected with a power of 10 W. In current stabilization mode (switch SA3 in the “FOR” position), the power dissipated by the resistor is 3.8 W. And even if you install a five-watt resistor, its power load will be 72% of the maximum permissible. Similarly, R7 type C5-16V has a power of 5 W, but MLT-2 can also be used. Resistor R6 is type MLT-2, but you can use MLT-1. R9 is a wire-wound variable resistor of type PPZ-43 with a power of 3 W. R5 type MLT-1. These resistors must be positioned so that they are cooled in the best possible way and do not, if possible, heat other elements of the circuit, as well as each other. To make the adjustment (set current) clearer, mark 10, 20, 50, 75 and 100 mA on the resistor R9 dial using an external milliammeter (tester) and connecting it directly to the power supply sockets.

Additional convenience when working with a power supply is provided by a pV voltmeter, which is an M95 microammeter with a total deviation current of 0.15 mA.
The resistance of resistor R11 is selected so that the final scale value corresponds to a voltage of 30 V. You can also use any other measuring head with a total deviation current of up to 1.5 mA by selecting a current-limiting resistor R11.
As switches SA2, SA3, biscuits are used - type 11P3NMP. To increase the permissible switching current, the equivalent terminals of the three biscuits are paralleled. The lock is installed depending on the number of positions.
Capacitor C5 is prefabricated and consists of five parallel-connected capacitors of type K50-12 with a capacity of 2000 μF x 50 V.

Transistor VT1 is installed externally on a radiator with an area of ​​400 cm2. It can be replaced with KT803A, KT808A, VT2 can be replaced with KT816G. A pair of transistors VT1, VT2 can be replaced with one KT827A, B, V or D. Any diodes VD6, VD7, preferably germanium with a lower forward voltage drop and a reverse voltage drop of at least 30 V. Diodes VD1 -VD4 type KD206A, KD202A, B, V or similar installed on radiators.

At self-production transformer TV1 can be guided by the methodology described in. The overall power of the transformer must be at least 100 W, preferably 120 W. In this case, it will be possible to wind up another winding with a voltage of 6.3 V. In this case, another range of 24 - 30 V will be added, which will provide an output voltage regulation range of 1.5-30 V at a load current of 3 A.

Setting up the power supply It is carried out according to a well-known method and has no special features. A correctly assembled power supply starts working immediately. When working with a power supply, first select the required output voltage range using the SA2 switch, and use the “RUB” and “FINE” resistors to set the required output voltage, based on the readings of the built-in voltmeter. Switch SA3 selects the current limit limit and connects the load. It should be noted that despite the simplicity of the circuit, this power supply combines two devices: a voltage stabilizer plus a current stabilizer. The power supply is not afraid of short circuits and can even protect the elements of an electronic device connected to it, which is very important when conducting various tests in amateur radio practice.

LITERATURE
1. Nefedov A.V., Aksenov A.I., Circuit elements of household radio equipment, microcircuits: Reference book.-M: Radio communication, 1993.
2. Akimov N.N., Resistors, capacitors, transformers, chokes, switching devices REA: Directory. - Minsk: Belarus, 1994.
3. Semiconductor receiving and amplifying devices: Amateur Radio Handbook / R.M. Tereshchuk, K.M. Tereshchuk. - Kyiv: Naukova Dumka, 1988.

Radiohobby 05-1999

List of radioelements

For two voltages (+5 and +12 V) is shown in Fig. 1:

The stabilizer provides two output voltages: 5 V, at a current of 0.75 A; 12 V at a current of about 200 mA. The main voltage generated pulse stabilizer, is the voltage +5 volts. The second voltage is obtained due to the autotransformer winding II of transformer T1.

Article " Laboratory block power supply", was published in the magazine No. 11 in 1980. According to the original source, in the 80s a functioning power supply was manufactured, which is still working today.

Main advantages laboratory nutrition are:

Wide range of output voltages (0... ±40 V);

Possibility of smooth adjustment of tension in the arms, both separately and symmetrically;

The boost circuit can be implemented on the MC33063A/MC34063A pulse converter controller, or their Russian analogue KR1156EU5R/KF1156EU5T. MC33063A/MC34063A microcircuits differ from each other only in the type of housing, i.e. DIP-8 or SO8 respectively. Input voltage from 3 to 40 volts.

In this circuit, the output of the converter produces 28 volts, with an input voltage of 12 volts, the load current will be 175 milliamps.

Another voltage value at the boost output can be obtained by changing the ratio R1/R2 according to the formula:

V out=1.25 x(1+R2/R1).

For implementation except