Power supply: with and without regulation, laboratory, pulsed, device, repair. List of circuit elements for an adjustable power supply on LM317 Powerful power supply on KT819GM

Making a power supply with your own hands makes sense not only for enthusiastic radio amateurs. A homemade power supply unit (PSU) will create convenience and save a considerable amount in the following cases:

• To power low-voltage power tools, to save expensive resources battery(battery);
• For electrification of premises that are particularly dangerous in terms of the degree of electric shock: basements, garages, sheds, etc. When powered by alternating current, a large amount of it in low-voltage wiring can create interference with household appliances and electronics;
• In design and creativity for precise, safe and waste-free cutting of foam plastic, foam rubber, low-melting plastics with heated nichrome;
• In lighting design - the use of special power supplies will extend life LED strip and get stable lighting effects. Powering underwater illuminators, etc. from a household electrical network is generally unacceptable;
• For charging phones, smartphones, tablets, laptops away from stable power sources;
• For electroacupuncture;
• And many other purposes not directly related to electronics.

Acceptable simplifications

Professional power supplies are designed to power any kind of load, incl. reactive. Possible consumers include precision equipment. The pro-BP must maintain the specified voltage with the highest accuracy for an indefinitely long time, and its design, protection and automation must allow operation by unqualified personnel in difficult conditions, for example. biologists to power their instruments in a greenhouse or on an expedition.

An amateur laboratory power supply is free from these limitations and therefore can be significantly simplified while maintaining quality indicators sufficient for personal use. Further, through also simple improvements, it is possible to obtain a special-purpose power supply from it. What are we going to do now?

Abbreviations

1. KZ – short circuit.
2. XX – idle speed, i.e. sudden disconnection of the load (consumer) or a break in its circuit.
3. VS – voltage stabilization coefficient. It is equal to the ratio of the change in input voltage (in % or times) to the same output voltage at a constant current consumption. Eg. The network voltage dropped completely, from 245 to 185V. Relative to the norm of 220V, this will be 27%. If the VS of the power supply is 100, the output voltage will change by 0.27%, which, with its value of 12V, will give a drift of 0.033V. More than acceptable for amateur practice.
4. IPN is a source of unstabilized primary voltage. This can be an iron transformer with a rectifier or a pulsed network voltage inverter (VIN).
5. IIN - operate at a higher (8-100 kHz) frequency, which allows the use of lightweight compact ferrite transformers with windings of several to several dozen turns, but they are not without drawbacks, see below.
6. RE – regulating element of the voltage stabilizer (SV). Maintains the output at its specified value.
7. ION – reference voltage source. Sets its reference value, according to which, together with the signals feedback The OS control device of the control unit acts on the RE.
8. SNN – continuous voltage stabilizer; simply “analog”.
9. ISN – pulse stabilizer voltage.
10. UPS – pulse block nutrition.

Note: both SNN and ISN can operate both from an industrial frequency power supply with a transformer on iron, and from an electrical power supply.

About computer power supplies

UPSs are compact and economical. And in the pantry many people have a power supply from an old computer lying around, obsolete, but quite serviceable. So is it possible to adapt a switching power supply from a computer for amateur/working purposes? Unfortunately, a computer UPS is a rather highly specialized device and the possibilities of its use at home/at work are very limited:

It is perhaps advisable for the average amateur to use a UPS converted from a computer one only to power power tools; about this see below. The second case is if an amateur is engaged in PC repair and/or creation logic circuits. But then he already knows how to adapt a power supply from a computer for this:

1. Load the main channels +5V and +12V (red and yellow wires) with nichrome spirals at 10-15% of the rated load;
2. The green soft start wire (low-voltage button on the front panel of the system unit) pc on is shorted to common, i.e. on any of the black wires;
3. On/off is performed mechanically, using a toggle switch on the rear panel of the power supply unit;
4. With mechanical (iron) I/O “on duty”, i.e. independent USB power+5V ports will also turn off.

Get to work!

Due to the shortcomings of UPSs, plus their fundamental and circuitry complexity, we will only look at a couple of them at the end, but simple and useful, and talk about the method of repairing the IPS. The main part of the material is devoted to SNN and IPN with industrial frequency transformers. They allow a person who has just picked up a soldering iron to build a power supply very High Quality. And having it on the farm, it will be easier to master “fine” techniques.

IPN

First, let's look at the IPN. We’ll leave pulse ones in more detail until the section on repairs, but they have something in common with “iron” ones: a power transformer, a rectifier and a ripple suppression filter. Together, they can be implemented in various ways depending on the purpose of the power supply.

Pos. 1 in Fig. 1 – half-wave (1P) rectifier. The voltage drop across the diode is the smallest, approx. 2B. But the pulsation of the rectified voltage is with a frequency of 50 Hz and is “ragged”, i.e. with intervals between pulses, so the pulsation filter capacitor Sf should be 4-6 times larger in capacity than in other circuits. The use of power transformer Tr for power is 50%, because Only 1 half-wave is rectified. For the same reason, a magnetic flux imbalance occurs in the Tr magnetic circuit and the network “sees” it not as an active load, but as inductance. Therefore, 1P rectifiers are used only for low power and where there is no other way, for example. in IIN on blocking generators and with a damper diode, see below.

Note: why 2V, and not 0.7V, at which the p-n junction in silicon opens? The reason is through current, which is discussed below.

Pos. 2 – 2-half-wave with midpoint (2PS). The diode losses are the same as before. case. The ripple is 100 Hz continuous, so the smallest possible Sf is needed. Use of Tr - 100% Disadvantage - double copper consumption on the secondary winding. At the time when rectifiers were made using kenotron lamps, this did not matter, but now it is decisive. Therefore, 2PS are used in low-voltage rectifiers, mainly at higher frequencies with Schottky diodes in UPSs, but 2PS have no fundamental limitations on power.

Pos. 3 – 2-half-wave bridge, 2RM. Losses on diodes are doubled compared to pos. 1 and 2. The rest is the same as 2PS, but the secondary copper is needed almost half as much. Almost - because several turns have to be wound to compensate for the losses on a pair of “extra” diodes. The most commonly used circuit is for voltages from 12V.

Pos. 3 – bipolar. The “bridge” is depicted conventionally, as is customary in circuit diagrams (get used to it!), and is rotated 90 degrees counterclockwise, but in fact it is a pair of 2PS connected in opposite polarities, as can be clearly seen further in Fig. 6. Copper consumption is the same as 2PS, diode losses are the same as 2PM, the rest is the same as both. It is built mainly to power analog devices that require voltage symmetry: Hi-Fi UMZCH, DAC/ADC, etc.

Pos. 4 – bipolar according to the parallel doubling scheme. Provides increased voltage symmetry without additional measures, because asymmetry of the secondary winding is excluded. Using Tr 100%, ripples 100 Hz, but torn, so Sf needs double capacity. Losses on the diodes are approximately 2.7V due to the mutual exchange of through currents, see below, and at a power of more than 15-20 W they increase sharply. They are built mainly as low-power auxiliary ones for independent power supply of operational amplifiers (op-amps) and other low-power, but demanding analog components in terms of power supply quality.

How to choose a transformer?

In a UPS, the entire circuit is most often clearly tied to the standard size (more precisely, to the volume and cross-sectional area Sc) of the transformer/transformers, because the use of fine processes in ferrite makes it possible to simplify the circuit while making it more reliable. Here, “somehow in your own way” comes down to strict adherence to the developer’s recommendations.

The iron-based transformer is selected taking into account the characteristics of the SNN, or is taken into account when calculating it. The voltage drop across the RE Ure should not be taken less than 3V, otherwise the VS will drop sharply. As Ure increases, the VS increases slightly, but the dissipated RE power grows much faster. Therefore, Ure is taken at 4-6 V. To it we add 2(4) V of losses on the diodes and the voltage drop on the secondary winding Tr U2; for a power range of 30-100 W and voltages of 12-60 V, we take it to 2.5 V. U2 arises primarily not from the ohmic resistance of the winding (it is generally negligible in powerful transformers), but due to losses due to magnetization reversal of the core and the creation of a stray field. Simply, part of the network energy, “pumped” by the primary winding into the magnetic circuit, evaporates into outer space, which is what the value of U2 takes into account.

So, we calculated, for example, for a bridge rectifier, 4 + 4 + 2.5 = 10.5 V extra. We add it to the required output voltage of the power supply unit; let it be 12V, and divide by 1.414, we get 22.5/1.414 = 15.9 or 16V, this will be the lowest permissible voltage of the secondary winding. If TP is factory-made, we take 18V from the standard range.

Now the secondary current comes into play, which, naturally, is equal to the maximum load current. Let us say we need 3A; multiply by 18V, it will be 54W. We have obtained the overall power Tr, Pg, and we will find the rated power P by dividing Pg by the efficiency Tr η, which depends on Pg:

• up to 10W, η = 0.6.
• 10-20 W, η = 0.7.
• 20-40 W, η = 0.75.
• 40-60 W, η = 0.8.
• 60-80 W, η = 0.85.
• 80-120 W, η = 0.9.
• from 120 W, η = 0.95.

In our case, there will be P = 54/0.8 = 67.5 W, but there is no such standard value, so you will have to take 80 W. In order to get 12Vx3A = 36W at the output. A steam locomotive, and that's all. It’s time to learn how to calculate and wind the “trances” yourself. Moreover, in the USSR, methods for calculating transformers on iron were developed that make it possible, without loss of reliability, to squeeze 600 W out of a core, which, when calculated according to amateur radio reference books, is capable of producing only 250 W. "Iron Trance" is not as stupid as it seems.

SNN

The rectified voltage needs to be stabilized and, most often, regulated. If the load is more powerful than 30-40 W, short-circuit protection is also necessary, otherwise a malfunction of the power supply may cause a network failure. SNN does all this together.

Simple reference

It is better for a beginner not to get involved right away. high power, and make a simple, highly stable 12V ELV for the sample according to the diagram in Fig. 2. It can then be used as a source of reference voltage (its exact value is set by R5), for checking devices, or as a high-quality ELV ION. The maximum load current of this circuit is only 40mA, but the VSC on the antediluvian GT403 and the equally ancient K140UD1 is more than 1000, and when replacing VT1 with a medium-power silicon one and DA1 on any of the modern op-amps it will exceed 2000 and even 2500. The load current will also increase to 150 -200 mA, which is already useful.

0-30

The next stage is a power supply with voltage regulation. The previous one was done according to the so-called. compensation comparison circuit, but it is difficult to convert one to a high current. We will make a new SNN based on an emitter follower (EF), in which the RE and CU are combined in just one transistor. The KSN will be somewhere around 80-150, but this will be enough for an amateur. But the SNN on the ED allows, without any special tricks, to obtain an output current of up to 10A or more, as much as the Tr will give and the RE will withstand.

The circuit of a simple 0-30V power supply is shown in pos. 1 Fig. 3. IPN for it is a ready-made transformer such as TPP or TS for 40-60 W with a secondary winding for 2x24V. Rectifier type 2PS with diodes rated at 3-5A or more (KD202, KD213, D242, etc.). VT1 is installed on a radiator with an area of ​​50 square meters or more. cm; An old PC processor will work very well. Under such conditions, this ELV is not afraid of a short circuit, only VT1 and Tr will heat up, so a 0.5A fuse in the primary winding circuit of Tr is enough for protection.

Pos. Figure 2 shows how convenient a power supply on an electric power supply is for an amateur: there is a 5A power supply circuit with adjustment from 12 to 36 V. This power supply can supply 10A to the load if there is a 400W 36V power supply. Its first feature is the integrated SNN K142EN8 (preferably with index B) acts in an unusual role as a control unit: to its own 12V output is added, partially or completely, all 24V, the voltage from the ION to R1, R2, VD5, VD6. Capacitors C2 and C3 prevent excitation on HF DA1 operating in an unusual mode.

The next point is the short circuit protection device (PD) on R3, VT2, R4. If the voltage drop across R4 exceeds approximately 0.7V, VT2 will open, close the base circuit of VT1 to the common wire, it will close and disconnect the load from the voltage. R3 is needed so that the extra current does not damage DA1 when the ultrasound is triggered. There is no need to increase its denomination, because when the ultrasound is triggered, you need to securely lock VT1.

And the last thing is the seemingly excessive capacitance of the output filter capacitor C4. In this case it is safe, because The maximum collector current of VT1 of 25A ensures its charge when turned on. But this ELV can supply a current of up to 30A to the load within 50-70 ms, so this simple power supply is suitable for powering low-voltage power tools: its starting current does not exceed this value. You just need to make (at least from plexiglass) a contact block-shoe with a cable, put on the heel of the handle, and let the “Akumych” rest and save resources before leaving.

About cooling

Let's say in this circuit the output is 12V with a maximum of 5A. This is just the average power of a jigsaw, but, unlike a drill or screwdriver, it takes it all the time. At C1 it stays at about 45V, i.e. on RE VT1 it remains somewhere around 33V at a current of 5A. Power dissipation is more than 150 W, even more than 160, if you consider that VD1-VD4 also needs to be cooled. It is clear from this that any powerful adjustable power supply must be equipped with a very effective cooling system.

A finned/needle radiator using natural convection does not solve the problem: calculations show that a dissipating surface of 2000 sq. m. is needed. see and the thickness of the radiator body (the plate from which the fins or needles extend) is from 16 mm. To own this much aluminum in a shaped product was and remains a dream in a crystal castle for an amateur. A CPU cooler with airflow is also not suitable; it is designed for less power.

One of the options for the home craftsman is an aluminum plate with a thickness of 6 mm and dimensions of 150x250 mm with holes of increasing diameter drilled along the radii from the installation site of the cooled element in a checkerboard pattern. It will also serve as the rear wall of the power supply housing, as in Fig. 4.

An indispensable condition for the effectiveness of such a cooler is a weak, but continuous flow of air through the perforations from the outside to the inside. To do this, install a low-power exhaust fan in the housing (preferably at the top). A computer with a diameter of 76 mm or more is suitable, for example. add. HDD cooler or video card. It is connected to pins 2 and 8 of DA1, there is always 12V.

Note: In fact, a radical way to overcome this problem is a secondary winding Tr with taps for 18, 27 and 36V. The primary voltage is switched depending on which tool is being used.

And yet the UPS

The described power supply for the workshop is good and very reliable, but it’s hard to carry it with you on trips. This is where a computer power supply will fit in: the power tool is insensitive to most of its shortcomings. Some modification most often comes down to installing an output (closest to the load) electrolytic capacitor of large capacity for the purpose described above. There are a lot of recipes for converting computer power supplies for power tools (mainly screwdrivers, which are not very powerful, but very useful) in RuNet; one of the methods is shown in the video below, for a 12V tool.

Video: 12V power supply from a computer

It’s even easier with 18V tools: they consume less current for the same power. A much more affordable ignition device (ballast) from a 40 W or more energy saving lamp may be useful here; it can be completely placed in the case of a bad battery, and only the cable with the power plug will remain outside. How to make a power supply for an 18V screwdriver from ballast from a burnt housekeeper, see the following video.

Video: 18V power supply for a screwdriver

High class

But let’s return to SNN on ES; their capabilities are far from being exhausted. In Fig. 5 – bipolar powerful power supply with 0-30 V regulation, suitable for Hi-Fi audio equipment and other fastidious consumers. The output voltage is set using one knob (R8), and the symmetry of the channels is maintained automatically at any voltage value and any load current. A pedant-formalist may turn gray before his eyes at the sight of this circuit, but the author has had such a power supply working properly for about 30 years.

The main stumbling block during its creation was δr = δu/δi, where δu and δi are small instantaneous increments of voltage and current, respectively. To develop and set up high-quality equipment, it is necessary that δr does not exceed 0.05-0.07 Ohm. Simply, δr determines the ability of the power supply to instantly respond to surges in current consumption.

For the SNN on the EP, δr is equal to that of the ION, i.e. zener diode divided by the current transfer coefficient β RE. But for powerful transistors, β drops significantly at a large collector current, and δr of a zener diode ranges from a few to tens of ohms. Here, in order to compensate for the voltage drop across the RE and reduce the temperature drift of the output voltage, we had to assemble a whole chain of them in half with diodes: VD8-VD10. Therefore, the reference voltage from the ION is removed through an additional ED on VT1, its β is multiplied by β RE.

The next feature of this design is short circuit protection. The simplest one, described above, does not fit into a bipolar circuit in any way, so the protection problem is solved according to the principle “there is no trick against scrap”: there is no protective module as such, but there is redundancy in the parameters of powerful elements - KT825 and KT827 at 25A and KD2997A at 30A. T2 is not capable of providing such a current, and while it warms up, FU1 and/or FU2 will have time to burn out.

Note: It is not necessary to indicate blown fuses on miniature incandescent lamps. It’s just that at that time LEDs were still quite scarce, and there were several handfuls of SMOKs in the stash.

It remains to protect the RE from the extra discharge currents of the pulsation filter C3, C4 during a short circuit. To do this, they are connected through low-resistance limiting resistors. In this case, pulsations may appear in the circuit with a period equal to the time constant R(3,4)C(3,4). They are prevented by C5, C6 of smaller capacity. Their extra currents are no longer dangerous for RE: the charge drains faster than the crystals of the powerful KT825/827 heat up.

Output symmetry is ensured by op-amp DA1. The RE of the negative channel VT2 is opened by current through R6. As soon as the minus of the output exceeds the plus in modulus, it will slightly open VT3, which will close VT2 and the absolute values ​​of the output voltages will be equal. Operational control over the symmetry of the output is carried out using a dial gauge with a zero in the middle of the P1 scale (in the inset - its appearance), and adjustment if necessary - R11.

The last highlight is the output filter C9-C12, L1, L2. This design is necessary to absorb possible HF interference from the load, so as not to rack your brain: the prototype is buggy or the power supply is “wobbly”. With electrolytic capacitors alone, shunted with ceramics, there is no complete certainty here; the large self-inductance of the “electrolytes” interferes. And chokes L1, L2 divide the “return” of the load across the spectrum, and to each their own.

This power supply unit, unlike the previous ones, requires some adjustment:

1. Connect a load of 1-2 A at 30V;
2. R8 is set to maximum, in the highest position according to the diagram;
3. Using a reference voltmeter (any digital multimeter will do now) and R11, the channel voltages are set to be equal in absolute value. Maybe, if the op-amp does not have the ability to balance, you will have to select R10 or R12;
4. Use the R14 trimmer to set P1 exactly to zero.

About power supply repair

PSUs fail more often than others electronic devices: they take the first blow of the network throws, they get a lot from the load. Even if you do not intend to make your own power supply, a UPS can be found, in addition to a computer, in a microwave oven, washing machine, and other household appliances. The ability to diagnose a power supply and knowledge of the basics of electrical safety will make it possible, if not to fix the fault yourself, then to competently bargain on the price with repairmen. Therefore, let's look at how a power supply is diagnosed and repaired, especially with an IIN, because over 80% of failures are their share.

Saturation and draft

First of all, about some effects, without understanding which it is impossible to work with a UPS. The first of them is the saturation of ferromagnets. They are not capable of absorbing energies of more than a certain value, depending on the properties of the material. Hobbyists rarely encounter saturation on iron; it can be magnetized to several Tesla (Tesla, a unit of measurement of magnetic induction). When calculating iron transformers, the induction is taken to be 0.7-1.7 Tesla. Ferrites can withstand only 0.15-0.35 T, their hysteresis loop is “more rectangular”, and operate at higher frequencies, so their probability of “jumping into saturation” is orders of magnitude higher.

If the magnetic circuit is saturated, the induction in it no longer grows and the EMF of the secondary windings disappears, even if the primary has already melted (remember school physics?). Now turn off the primary current. The magnetic field in soft magnetic materials (hard magnetic materials are permanent magnets) cannot exist stationary, as electric charge or water in the tank. It will begin to dissipate, the induction will drop, and an EMF of the opposite polarity relative to the original polarity will be induced in all windings. This effect is quite widely used in IIN.

Unlike saturation, through current in semiconductor devices (simply draft) is an absolutely harmful phenomenon. It arises due to the formation/resorption of space charges in the p and n regions; for bipolar transistors - mainly in the base. Field-effect transistors and Schottky diodes are practically free from drafts.

For example, when voltage is applied/removed to a diode, it conducts current in both directions until the charges are collected/dissolved. That is why the voltage loss on the diodes in rectifiers is more than 0.7V: at the moment of switching, part of the charge of the filter capacitor has time to flow through the winding. In a parallel doubling rectifier, the draft flows through both diodes at once.

A draft of transistors causes a voltage surge on the collector, which can damage the device or, if a load is connected, damage it through extra current. But even without that, a transistor draft increases dynamic energy losses, like a diode draft, and reduces the efficiency of the device. Powerful field effect transistors they are almost not susceptible to it, because do not accumulate charge in the base due to its absence, and therefore switch very quickly and smoothly. “Almost”, because their source-gate circuits are protected from reverse voltage by Schottky diodes, which are slightly, but through.

TIN types

UPS trace their origins to the blocking generator, pos. 1 in Fig. 6. When turned on, Uin VT1 is slightly opened by current through Rb, current flows through winding Wk. It cannot instantly grow to the limit (remember school physics again); an emf is induced in the base Wb and load winding Wn. From Wb, through Sb, it forces the unlocking of VT1. No current flows through Wn yet and VD1 does not start up.

When the magnetic circuit is saturated, the currents in Wb and Wn stop. Then, due to the dissipation (resorption) of energy, the induction drops, an EMF of the opposite polarity is induced in the windings, and the reverse voltage Wb instantly locks (blocks) VT1, saving it from overheating and thermal breakdown. Therefore, such a scheme is called a blocking generator, or simply blocking. Rk and Sk cut off HF interference, of which blocking produces more than enough. Now some useful power can be removed from Wn, but only through the 1P rectifier. This phase continues until the Sat is completely recharged or until the stored magnetic energy is exhausted.

This power, however, is small, up to 10W. If you try to take more, VT1 will burn out from a strong draft before it locks. Since Tp is saturated, the blocking efficiency is no good: more than half of the energy stored in the magnetic circuit flies away to warm other worlds. True, due to the same saturation, blocking to some extent stabilizes the duration and amplitude of its pulses, and its circuit is very simple. Therefore, blocking-based TINs are often used in cheap phone chargers.

Note: the value of Sb largely, but not completely, as they write in amateur reference books, determines the pulse repetition period. The value of its capacitance must be linked to the properties and dimensions of the magnetic circuit and the speed of the transistor.

Blocking at one time gave rise to line scan TVs with cathode ray tubes (CRT), and it gave birth to an INN with a damper diode, pos. 2. Here the control unit, based on signals from Wb and the DSP feedback circuit, forcibly opens/locks VT1 before Tr is saturated. When VT1 is locked, the reverse current Wk is closed through the same damper diode VD1. This is the working phase: already greater than in blocking, part of the energy is removed into the load. It’s big because when it’s completely saturated, all the extra energy flies away, but here there’s not enough of that extra. In this way it is possible to remove power up to several tens of watts. However, since the control unit cannot operate until Tr has approached saturation, the transistor still shows through strongly, the dynamic losses are large and the efficiency of the circuit leaves much more to be desired.

The IIN with a damper is still alive in televisions and CRT displays, since in them the IIN and the horizontal scan output are combined: the power transistor and TP are common. This greatly reduces production costs. But, frankly speaking, an IIN with a damper is fundamentally stunted: the transistor and transformer are forced to work all the time on the verge of failure. The engineers who managed to bring this circuit to acceptable reliability deserve the deepest respect, but it is strongly not recommended to stick a soldering iron in there except for professionals who have undergone professional training and have the appropriate experience.

The push-pull INN with a separate feedback transformer is most widely used, because has the best quality indicators and reliability. However, in terms of RF interference, it also sins terribly in comparison with “analog” power supplies (with transformers on hardware and SNN). Currently, this scheme exists in many modifications; powerful bipolar transistors in it are almost completely replaced by field-effect ones controlled by special devices. IC, but the principle of operation remains unchanged. It is illustrated by the original diagram, pos. 3.

The limiting device (LD) limits the charging current of the capacitors of the input filter Sfvkh1(2). Their large size is an indispensable condition for the operation of the device, because During one operating cycle, a small fraction of the stored energy is taken from them. Roughly speaking, they play the role of a water tank or air receiver. When charging “short”, the extra charge current can exceed 100A for a time of up to 100 ms. Rc1 and Rc2 with a resistance of the order of MOhm are needed to balance the filter voltage, because the slightest imbalance of his shoulders is unacceptable.

When Sfvkh1(2) are charged, the ultrasonic trigger device generates a trigger pulse that opens one of the arms (which one does not matter) of the inverter VT1 VT2. A current flows through the winding Wk of a large power transformer Tr2 and the magnetic energy from its core through the winding Wn is almost completely spent on rectification and on the load.

A small part of the energy Tr2, determined by the value of Rogr, is removed from the winding Woc1 and supplied to the winding Woc2 of a small basic feedback transformer Tr1. It quickly saturates, the open arm closes and, due to dissipation in Tr2, the previously closed one opens, as described for blocking, and the cycle repeats.

In essence, a push-pull IIN is 2 blockers “pushing” each other. Since the powerful Tr2 is not saturated, the draft VT1 VT2 is small, completely “sinks” into the magnetic circuit Tr2 and ultimately goes into the load. Therefore, a two-stroke IPP can be built with a power of up to several kW.

It's worse if he ends up in XX mode. Then, during the half cycle, Tr2 will have time to saturate itself and a strong draft will burn both VT1 and VT2 at once. However, now there are power ferrites on sale for induction up to 0.6 Tesla, but they are expensive and degrade from accidental magnetization reversal. Ferrites with a capacity of more than 1 Tesla are being developed, but in order for IINs to achieve “iron” reliability, at least 2.5 Tesla is needed.

Diagnostic technique

When troubleshooting an “analog” power supply, if it is “stupidly silent,” first check the fuses, then the protection, RE and ION, if it has transistors. They ring normally - we move on element by element, as described below.

In the IIN, if it “starts up” and immediately “stalls out”, they first check the control unit. The current in it is limited by a powerful low-resistance resistor, then shunted by an optothyristor. If the “resistor” is apparently burnt, replace it and the optocoupler. Other elements of the control device fail extremely rarely.

If the IIN is “silent, like a fish on ice,” the diagnosis also begins with the OU (maybe the “rezik” has completely burned out). Then - ultrasound. Cheap models use transistors in avalanche breakdown mode, which is far from being very reliable.

The next stage in any power supply is electrolytes. Fracture of the housing and leakage of electrolyte are not nearly as common as they write on the RuNet, but loss of capacity occurs much more often than failure of active elements. Electrolytic capacitors are checked with a multimeter capable of measuring capacitance. Below the nominal value by 20% or more - we put the “dead guy” in the sludge and install a new, good one.

Then there are the active elements. You probably know how to dial diodes and transistors. But there are 2 tricks here. The first is that if a Schottky diode or zener diode is called by a tester with a 12V battery, then the device may show a breakdown, although the diode is quite good. It is better to call these components using a pointer device with a 1.5-3 V battery.

The second is powerful field workers. Above (did you notice?) it is said that their I-Z are protected by diodes. Therefore, powerful field-effect transistors seem to sound like serviceable bipolar transistors, even if they are unusable if the channel is “burnt out” (degraded) not completely.

Here, the only way available at home is to replace them with known good ones, both at once. If there is a burnt one left in the circuit, it will immediately pull a new working one with it. Electronics engineers joke that powerful field workers cannot live without each other. Another prof. joke – “replacement gay couple.” This means that the transistors of the IIN arms must be strictly of the same type.

Finally, film and ceramic capacitors. They are characterized by internal breaks (found by the same tester that checks the “air conditioners”) and leakage or breakdown under voltage. To “catch” them, you need to assemble a simple circuit according to Fig. 7. Step-by-step testing of electrical capacitors for breakdown and leakage is carried out as follows:

• We set on the tester, without connecting it anywhere, the smallest limit for measuring direct voltage (most often 0.2V or 200mV), detect and record the device’s own error;
• We turn on the measurement limit of 20V;
• We connect the suspicious capacitor to points 3-4, the tester to 5-6, and to 1-2 we apply a constant voltage of 24-48 V;
• Switch the multimeter voltage limits down to the lowest;
• If on any tester it shows anything other than 0000.00 (at the very least - something other than its own error), the capacitor being tested is not suitable.

This is where the methodological part of the diagnosis ends and the creative part begins, where all the instructions are based on your own knowledge, experience and considerations.

A couple of impulses

UPSs are a special article due to their complexity and circuit diversity. Here, to begin with, we will consider a couple of samples using pulse width modulation (PWM), which allows us to obtain best quality UPS. There are a lot of PWM circuits in RuNet, but PWM is not as scary as it is made out to be...

For lighting design

You can simply light the LED strip from any power supply described above, except for the one in Fig. 1, setting the required voltage. SNN with pos. 1 Fig. 3, it’s easy to make 3 of these, for channels R, G and B. But the durability and stability of the LEDs’ glow does not depend on the voltage applied to them, but on the current flowing through them. Therefore, a good power supply for LED strip should include a load current stabilizer; in technical terms - a stable current source (IST).

One of the schemes for stabilizing the light strip current, which can be repeated by amateurs, is shown in Fig. 8. It is assembled on an integrated timer 555 ( domestic analogue– K1006VI1). Provides a stable tape current from a power supply voltage of 9-15 V. The amount of stable current is determined by the formula I = 1/(2R6); in this case - 0.7A. Powerful transistor VT3 is necessarily a field one; from a draft, due to the charge of the base, a bipolar PWM simply will not form. Inductor L1 is wound on a ferrite ring 2000NM K20x4x6 with a 5xPE 0.2 mm harness. Number of turns – 50. Diodes VD1, VD2 – any silicon RF (KD104, KD106); VT1 and VT2 – KT3107 or analogues. With KT361, etc. The input voltage and brightness control ranges will decrease.

The circuit works like this: first, the time-setting capacitance C1 is charged through the R1VD1 circuit and discharged through VD2R3VT2, open, i.e. in saturation mode, through R1R5. The timer generates a sequence of pulses with the maximum frequency; more precisely - with a minimum duty cycle. The VT3 inertia-free switch generates powerful impulses, and its VD3C4C3L1 harness smooths them out to direct current.

Note: The duty cycle of a series of pulses is the ratio of their repetition period to the pulse duration. If, for example, the pulse duration is 10 μs, and the interval between them is 100 μs, then the duty cycle will be 11.

The current in the load increases, and the voltage drop across R6 opens VT1, i.e. transfers it from the cut-off (locking) mode to the active (reinforcing) mode. This creates a leakage circuit for the base of VT2 R2VT1+Upit and VT2 also goes into active mode. The discharge current C1 decreases, the discharge time increases, the duty cycle of the series increases and the average current value drops to the norm specified by R6. This is the essence of PWM. At minimum current, i.e. at maximum duty cycle, C1 is discharged through the VD2-R4-internal timer switch circuit.

In the original design, the ability to quickly adjust the current and, accordingly, the brightness of the glow is not provided; There are no 0.68 ohm potentiometers. The easiest way to adjust the brightness is by connecting, after adjustment, a 3.3-10 kOhm potentiometer R* into the gap between R3 and the VT2 emitter, highlighted in brown. By moving its engine down the circuit, we will increase the discharge time of C4, the duty cycle and reduce the current. Another way is to bypass the base junction of VT2 by turning on a potentiometer of approximately 1 MOhm at points a and b (highlighted in red), less preferable, because the adjustment will be deeper, but rougher and sharper.

Unfortunately, to set up this useful not only for IST light tapes, you need an oscilloscope:

1. The minimum +Upit is supplied to the circuit.
2. By selecting R1 (impulse) and R3 (pause) we achieve a duty cycle of 2, i.e. The pulse duration must be equal to the pause duration. You cannot give a duty cycle less than 2!
3. Serve maximum +Upit.
4. By selecting R4, the rated value of a stable current is achieved.

For charging

In Fig. 9 – diagram of the simplest ISN with PWM, suitable for charging a phone, smartphone, tablet (a laptop, unfortunately, will not work) from a homemade solar battery, wind generator, motorcycle or car battery, magneto flashlight “bug” and other low-power unstable random sources power supply See the diagram for the input voltage range, there is no error there. This ISN is indeed capable of producing an output voltage greater than the input. As in the previous one, here there is the effect of changing the polarity of the output relative to the input; this is generally a proprietary feature of PWM circuits. Let's hope that after reading the previous one carefully, you will understand the work of this tiny little thing yourself.

Incidentally, about charging and charging

Charging batteries is a very complex and delicate physical and chemical process, the violation of which reduces their service life several times or tens of times, i.e. number of charge-discharge cycles. The charger must, based on very small changes in battery voltage, calculate how much energy has been received and regulate the charging current accordingly according to a certain law. That's why Charger is by no means a power supply and only batteries in devices with a built-in charge controller can be charged from ordinary power supplies: phones, smartphones, tablets, certain models of digital cameras. And charging, which is a charger, is a subject for a separate discussion.

Question-remont.ru said:

There will be some sparking from the rectifier, but it's probably not a big deal. The point is the so-called. differential output impedance of the power supply. For alkaline batteries it is about mOhm (milliohms), for acid batteries it is even less. A trance with a bridge without smoothing has tenths and hundredths of an ohm, i.e. approx. 100 – 10 times more. And the starting current of a brushed DC motor can be 6-7 or even 20 times greater than the operating current. Yours is most likely closer to the latter - fast-accelerating motors are more compact and more economical, and the huge overload capacity of the batteries allows you to give the engine as much current as it can handle. for acceleration. A trans with a rectifier will not provide as much instantaneous current, and the engine accelerates more slowly than it was designed for, and with a large slip of the armature. From this, from the large slip, a spark arises, and then remains in operation due to self-induction in the windings.

What can I recommend here? First: take a closer look - how does it spark? You need to watch it in operation, under load, i.e. during sawing.

If sparks dance in certain places under the brushes, it’s okay. My powerful Konakovo drill sparkles so much from birth, and for goodness sake. In 24 years, I changed the brushes once, washed them with alcohol and polished the commutator - that’s all. If you connected an 18V instrument to a 24V output, then a little sparking is normal. Unwind the winding or extinguish the excess voltage with something like a welding rheostat (a resistor of approximately 0.2 Ohm for a dissipation power of 200 W or more), so that the motor operates at the rated voltage and, most likely, the spark will go away. If you connected it to 12 V, hoping that after rectification it would be 18, then in vain - the rectified voltage drops significantly under load. And the commutator electric motor, by the way, doesn’t care whether it is powered by direct current or alternating current.

Specifically: take 3-5 m of steel wire with a diameter of 2.5-3 mm. Roll into a spiral with a diameter of 100-200 mm so that the turns do not touch each other. Place on a fireproof dielectric pad. Clean the ends of the wire until shiny and fold them into “ears”. It is best to immediately lubricate with graphite lubricant to prevent oxidation. This rheostat is connected to the break in one of the wires leading to the instrument. It goes without saying that the contacts should be screws, tightened tightly, with washers. Connect the entire circuit to the 24V output without rectification. The spark is gone, but the power on the shaft has also dropped - the rheostat needs to be reduced, one of the contacts needs to be switched 1-2 turns closer to the other. It still sparks, but less - the rheostat is too small, you need to add more turns. It is better to immediately make the rheostat obviously large so as not to screw on additional sections. It’s worse if the fire is along the entire line of contact between the brushes and the commutator or spark tails trail behind them. Then the rectifier needs an anti-aliasing filter somewhere, according to your data, from 100,000 µF. Not a cheap pleasure. The “filter” in this case will be an energy storage device for accelerating the motor. But it may not help if the overall power of the transformer is not enough. Efficiency of brushed DC motors is approx. 0.55-0.65, i.e. trans is needed from 800-900 W. That is, if the filter is installed, but still sparks with fire under the entire brush (under both, of course), then the transformer is not up to the task. Yes, if you install a filter, then the diodes of the bridge must be rated for triple the operating current, otherwise they may fly out from the surge of charging current when connected to the network. And then the tool can be launched 5-10 seconds after being connected to the network, so that the “banks” have time to “pump up”.

And the worst thing is if the tails of sparks from the brushes reach or almost reach the opposite brush. This is called all-round fire. It very quickly burns out the collector to the point of complete disrepair. There can be several reasons for a circular fire. In your case, the most probable is that the motor was turned on at 12 V with rectification. Then, at a current of 30 A, the electrical power in the circuit is 360 W. The anchor slides more than 30 degrees per revolution, and this is necessarily a continuous all-round fire. It is also possible that the motor armature is wound with a simple (not double) wave. Such electric motors are better at overcoming instantaneous overloads, but they have a starting current - mother, don’t worry. I can’t say more precisely in absentia, and there’s no point in it – there’s hardly anything we can fix here with our own hands. Then it will probably be cheaper and easier to find and purchase new batteries. But first, try turning on the engine at a slightly higher voltage through the rheostat (see above). Almost always, in this way it is possible to shoot down a continuous all-round fire at the cost of a small (up to 10-15%) reduction in power on the shaft.

Beginner Radio Amateur Competition
“My amateur radio design”

Simple design laboratory block power supply on transistors from “0” to “12” volts, and detailed description the entire device manufacturing process

Competition design for a beginner radio amateur:
“Adjustable power supply 0-12 V transistorized”

Hello dear friends and site guests!
I present to your consideration the fourth competition entry.
Author of the design - Folkin Dmitry, Zaporozhye, Ukraine.

Adjustable 0-12 V transistor power supply

I needed a power supply that was adjustable from 0 to ... B (the more, the better). I reviewed several books and settled on the design proposed in Borisov’s book “ Young radio amateur" Everything is laid out very well there, just for a beginner radio amateur. In the process of creating such a complex device for me, I made some mistakes, the analysis of which I made in this material. My device consists of two parts: the electrical part and the wooden body.

Part 1. Electrical part of the power supply.

Picture 1 - Fundamental electrical diagram power supply from the book

I started by selecting the necessary parts. I found some of them at home, and bought others on the radio market.

Figure 2 – Electrical parts

In Fig. 2 the following details are presented:

1 – voltmeter, showing the output voltage of the power supply unit (I bought an unnamed voltmeter with three scales, to which a shunt resistor must be selected for correct readings);
2 – fork mains power BP(I took a charger from Motorola, took out the board, and left the plug);
3 – light bulb with socket, which will serve as an indicator that the power supply is connected to the network (12.5 V 0.068 A light bulb, I found two of these in some old radio);
4 – switch from the power extension cord for a computer (there is a light bulb inside, unfortunately, mine was burnt out);
5 – 10 kOhm variable adjustment resistor of group A, i.e. with linear functional characteristic and a handle for it; needed to smoothly change the output voltage of the power supply (I took SP3-4am, and the knob from the radio);
6 – red “+” and black “-” terminals, used to connect the load to the power supply;
7 – fuse 0.5 A, installed in clamps on the legs (I found a glass fuse 6T500 with four legs in an old radio);
8 – step-down transformer 220 V/12 V also on four legs (TVK-70 is possible; I had one without markings, but the seller wrote “12 V” on it);
9 – four diodes with a maximum rectified current of 0.3 A for a rectifier diode bridge (you can use D226, D7 series with any letter or rectifier block KTs402; I took D226B);
10 – medium or high power transistor with a radiator and a fixing flange (you can use P213B or P214 - P217; I took the P214 immediately with a radiator so that it does not get hot);
11 – two 500 µF electrolytic capacitors or more, one 15 V or more, the second 25 V or more (K50-6 is possible; I took K50-35 both at 1000 uF, one 16 V, the second 25 V);
12 – zener diode with stabilization voltage 12 V(you can use D813, D811 or D814G; I took D813);
13 – low-power low-frequency transistor(you can MP39, MP40 - MP42; I have MP41A);
14 – constant resistor 510 Ohm, 0.25 W(you can use MLT; I took the SP4-1 trimmer for 1 kOhm, because its resistance will need to be selected);
15 – constant resistor 1 kOhm, 0.25 W(I came across a highly accurate one ±1%);
16 – constant resistor 510 Ohm, 0.25 W(I have MLT)
Also for the electrical part I needed:
– one-sided foil textolite(Fig. 3);
– homemade mini drill with drills with a diameter of 1, 1.5, 2, 2.5 mm;
– wires, bolts, nuts and other materials and tools.

Figure 3 – At the radio market I came across a very old Soviet textolite

Next, measuring the geometric dimensions of the existing elements, I drew the future board in a program that does not require installation. Then I started making printed circuit board LUT method. I did this for the first time, so I used this video tutorial _http://habrahabr.ru/post/45322/.

Stages of manufacturing a printed circuit board:

1 . Printed at the printing house laser printer I drew a board on glossy paper 160 g/m2 and cut it out (Fig. 4).

Figure 4 – Image of tracks and arrangement of elements on glossy paper

2 . I cut a piece of PCB measuring 190x90 mm. In the absence of metal scissors, I used ordinary office scissors, which took a long time and was difficult to cut. Using zero grade sandpaper and 96% ethyl alcohol, I prepared the textolite for toner transfer (Fig. 5).

Figure 5 – Prepared foil textolite

3 . First, using an iron, I transferred the toner from the paper to the metallized part of the PCB and heated it for a long time, about 10 minutes (Fig. 6). Then I remembered that I also wanted to do silk-screen printing, i.e. drawing a picture on the board from the parts side. I applied the paper with the image of the parts to the non-metalized part of the PCB, heated it for a short time, about 1 minute, it turned out rather poorly. Still, first it was necessary to silk-screen, and then transfer the tracks.

Figure 6 – Paper on PCB after heating with an iron

4 . Next, you need to remove this paper from the surface of the PCB. I used warm water and a shoe brush with metallic bristles in the middle (Figure 7). I scrubbed the paper very diligently. Perhaps it was a mistake.

Figure 7 – Brush for footwear

5 . After washing off the glossy paper, in Figure 8 you can see that the toner has dried out, but some of the tracks are torn. This is probably due to the hard work with the brush. Therefore, I had to buy a marker for CD\DVD discs and use it to draw almost all the tracks and contacts manually (Fig. 9).

Figure 8 – Textolite after transferring toner and removing paper

Figure 9 – Paths completed with marker

6 . Next, you need to etch out the unnecessary metal from the PCB, leaving the drawn tracks. I did it this way: I poured 1 liter of warm water into a plastic bowl, poured half a jar of ferric chloride into it and stirred it with a plastic teaspoon. Then I put foil PCB with marked tracks there (Fig. 10). On a jar of ferric chloride, the promised etching time is 40-50 minutes (Fig. 11). After waiting for the specified time, I did not find any changes on the future board. Therefore, I poured all the ferric chloride that was in the jar into water and stirred it. During the etching process, I stirred the solution with a plastic spoon to speed up the process. It took a long time, about 4 hours. To speed up the etching, it would be possible to heat the water, but I did not have such an opportunity. The ferric chloride solution can be reconstituted using iron nails. I didn't have any, so I used thick bolts. Copper settled on the bolts, and a precipitate appeared in the solution. I poured the solution into a three-liter plastic bottle with a thick neck and placed it in the pantry.

Figure 10 – A printed circuit board blank floats in a ferric chloride solution

Figure 11 – Jar of ferric chloride (weight not indicated)

7 . After etching (Fig. 12), I carefully washed the board with warm water and soap and removed the toner from the tracks with ethyl alcohol (Fig. 13).

Figure 12 – Textolite with etched tracks and toner

Figure 13 – Textolite with etched tracks without toner

8 . Next I started drilling the holes. For this I have a homemade mini drill (Fig. 14). To make it we had to disassemble the old broken one. Canon printer i250. From there I took a 24 V, 0.8 A motor, a power supply for it and a button. Then, at the radio market, I purchased a collet chuck for a 2 mm shaft and 2 sets of drills with a diameter of 1, 1.5, 2, 2.5 mm (Fig. 15). The chuck is put on the motor shaft, a drill with a holder is inserted and clamped. On top of the motor I glued and soldered a button that powers the mini-drill. The drills are not particularly easy to center, so they “drift” a little to the sides when working, but they can be used for amateur purposes.

Figure 14 –

Figure 15 –

Figure 16 – Board with drilled holes

9 . Then I cover the board with flux, lubricating it with a thick layer of pharmaceutical glycerin using a brush. After this, you can tin the tracks, i.e. cover them with a layer of tin. Starting with wide traces, I moved a large drop of solder on the soldering iron along the traces until I completely tinned the board (Fig. 17).

Figure 17 – Tinned board

10. At the end, I installed the parts on the board. I started with the most massive transformer and radiator, and finished with transistors (I read somewhere that transistors are always soldered at the end) and connecting wires. Also at the end of installation, the zener diode circuit break, marked in Fig. 1 with a cross, I turned on the multimeter and selected the resistance of the tuning resistor SP4-1 so that a current of 11 mA is established in this circuit. This setup is described in Borisov’s book “Young Radio Amateur”.

Figure 18 – Board with parts: bottom view

Figure 19 – Board with parts: top view

In Figure 18 you can see that I was slightly wrong with the location of the holes for mounting the transformer and radiator, so I had to drill more. Also, almost all the holes for radio components turned out to be slightly smaller in diameter, because the legs of the radio components did not fit. Perhaps the holes became smaller after tinning with solder, so they should be drilled after tinning. Separately, it should be said about the holes for the transistors - their location also turned out to be incorrect. Here I had to draw the diagram more carefully and carefully in the Sprint-Layout program. When arranging the base, emitter and collector of the P214 transistor, I should have taken into account that the radiator is installed on the board with its lower side (Fig. 20). To solder the terminals of the P214 transistor to the required tracks, I had to use copper pieces of wire. And for the MP41A transistor it was necessary to bend the base terminal in the other direction (Fig. 21).

Figure 20 – Holes for the terminals of the transistor P214

Figure 21 – Holes for the terminals of the MP41A transistor

Part 2. Manufacturing of a wooden power supply case.

For the case I needed:
- 4 plywood boards 220x120 mm;
– 2 plywood boards 110x110 mm;
– 4 plywood pieces 10x10x110 mm;
– 4 plywood pieces 10x10x15 mm;
– nails, 4 tubes of superglue.

Stages of manufacturing the case:

1 . First, I sawed a large piece of plywood into boards and pieces of the required size (Fig. 22).

Figure 22 – Sawn plywood boards for the body

2 . Then I used a mini drill to drill a hole for the wires to the power supply plug.
3 . Then I connected the bottom and side walls of the case using nails and superglue.
4 . Next I glued the internal wooden parts of the structure. Long racks (10x10x110 mm) are glued to the bottom and sides, holding the side walls together. I glued small square pieces to the bottom; the printed circuit board will be installed and secured on them (Fig. 23). I also secured wire holders inside the plug and at the back of the case (Fig. 24).

Figure 23 – Housing: front view (glue stains visible)

Figure 24 – Case: side view (and here the glue makes itself felt)

5 . On the front panel of the case there were: a voltmeter, a light bulb, a switch, a variable resistor, and two terminals. I needed to drill five round and one rectangular holes. This took a long time, since there were no necessary tools and we had to use what was at hand: a mini drill, a rectangular file, scissors, sandpaper. In Fig. 25 you can see a voltmeter, to one of the contacts of which a 100 kOhm shunt trimming resistor is connected. Experimentally, using a 9 V battery and a multimeter, it was found that the voltmeter gives correct readings with a shunt resistance of 60 kOhm. The light bulb socket was glued perfectly with superglue, and the switch was firmly fixed in the rectangular hole even without glue. The variable resistor screwed well into the wood, and the terminals were secured with nuts and bolts. I removed the backlight bulb from the switch, so instead of three there were two contacts left on the switch.

Figure 25 – PSU internals

Having secured the board in the case, installed the necessary elements on the front panel, connected the components using wires and attached the front wall with superglue, I received a ready-made functional device (Fig. 26).

Figure 26 – Ready power supply

In Fig. 26 you can see from the color that the light bulb is different from the one that was originally selected. Indeed, when connecting a 12.5 V light bulb rated for a current of 0.068 A to the secondary winding of the transformer (as indicated in the book), it burned out after a few seconds of operation. Probably due to the high current in the secondary winding. It was necessary to find a new location for connecting the light bulb. I replaced the light bulb with a whole one of the same parameters, but painted dark blue (so that it wouldn’t dazzle my eyes) and using wires I soldered it in parallel after capacitor C1. Now it works for a long time, but the book indicates the voltage in that circuit is 17 V and I'm afraid I'll have to look for a new place for the light bulb again. Also in Fig. 26 you can see that a spring is inserted into the switch from above. It is necessary for reliable operation of the button, which was loose. The handle on the variable resistor, which changes the output voltage of the power supply unit, has been shortened for better ergonomics.
When turning on the power supply, I check the readings of the voltmeter and multimeter (Fig. 27 and 28). The maximum output voltage is 11 V (1 V disappeared somewhere). Next, I decided to measure the maximum output current and when I set the maximum limit of 500 mA on the multimeter, the needle went off scale. This means that the maximum output current is slightly greater than 500 mA. When turning the handle smoothly variable resistor The output voltage of the power supply unit also changes smoothly. But the change in voltage from zero does not start immediately, but after about 1/5 of a turn of the knob.

So, after spending a significant amount of time, effort and finances, I finally assembled a power supply with an adjustable output voltage of 0 - 11 V and an output current of more than 0.5 A. If I could do it, then so can anyone else. Good luck to all!

Figure 27 – Checking the power supply

Figure 28 – Checking the correct voltmeter readings

Figure 29 – Setting the output voltage to 5V and checking with a test light

Dear friends and site guests!

Don’t forget to express your opinion on the competition entries and take part in discussions on the site’s forum. Thank you.

Applications to the design:

(15.0 KiB, 1,658 hits)

(38.2 KiB, 1,537 hits)

(21.0 KiB, 1,045 hits)

Power supply 1-30V on LM317 + 3 x TIP41C
or 3 x 2SC5200.

The article discusses the circuit of a simple regulated power supply, implemented on the LM317 stabilizer chip, which controls powerful three NPN transistors connected in parallel. The output voltage adjustment limits are 1.2...30 Volts with a load current of up to 10 Amps. TIP41C transistors in a TO220 package are used as powerful outputs; their collector current is 6 Amperes, power dissipation is 65 Watts. The circuit diagram of the power supply is shown below:

As outputs, you can also use TIP132C, TO220 housing, the collector current of these transistors is 8 Amps, power dissipation is 70 Watts according to the datasheet.

The pin locations for transistors TIP132C, TIP41C are as follows:

Pin layout of the adjustable stabilizer LM317:

Transistors in the TO220 package are soldered directly into the printed circuit board and attached to one common heatsink using mica, thermal paste and insulating bushings. But you can also use transistors in the TO-3 package; imported ones are suitable, for example, 2N3055, whose collector current is up to 15 Amps, power dissipation is 115 Watts, or domestically produced KT819GM ​​transistors, they are 15 Amperes with a power dissipation of 100 Watts. In this case, the terminals of the transistors are connected to the board by wires.

As an option, you can consider using imported 15-amp TOSHIBA 2SC5200 transistors with a power dissipation of 150 Watts. It was this transistor that I used when remaking the KIT kit of a power supply purchased on Aliexpress.

On schematic diagram terminals PAD1 and PAD2 are intended for connecting an ammeter, terminals X1-1 (+) and X1-2 (-) supply input voltage from the rectifier (diode bridge), X2-1 (-) and X2-2 (+) are output terminals power supply, a voltmeter is connected to terminal block JP1.

The first version of the printed circuit board is designed for installing power transistors in a TO220 package, the LAY6 format is as follows:

Photo view of the LAY6 format board:

The second version of the printed circuit board for installing transistors of type 2SC5200, type LAY6 format below:

Photo view of the second version of the power supply circuit board:

The third version of the printed circuit board is the same, but without the diode assembly, you will find it in the archive with the rest of the materials.

List of elements of the regulated power supply circuit on LM317:

Resistors:

R1 – potentiometer 5K – 1 pc.
R2 – 240R 0.25W – 1 pc.
R3, R4, R5 – ceramic resistors 5W 0R1 – 3 pcs.
R6 – 2K2 0.25W – 1 pc.

Capacitors:

C1, C2 – 4700...6800mF/50V – 2 pcs.
C3 – 1000...2200mF/50V – 1 pc.
C4 – 150...220mF/50V – 1 pc.
C5, C6, C7 – 0.1mF = 100n – 3 pcs.

Diodes:

D1 – 1N5400 – 1 pc.
D1 – 1N4004 – 1 pc.
LED1 – LED – 1 pc.
Diode assembly - I did not have assemblies for a slightly lower current, so the board was designed to use KBPC5010 (50 Amperes) - 1 pc.

Transistors, microcircuits:

IC1 – LM317MB – 1 pc.
Q1, Q2, Q3 – TIP132C, TIP41C, KT819GM, 2N3055, 2SC5200 – 3 pcs.

Rest:

2 Pin connectors with bolt clamp (input, output, ammeter) – 3 pcs.
Connector 2 Pin 2.54mm (LED, control variable) – 2 pcs.
In principle, you don’t have to install connectors.
Impressive radiator for weekenders – 1 pc.
Transformer, secondary at 22...24 Volts alternating, capable of carrying a current of about 10...12 Amps.

The archive file size with materials on the power supply for LM317 10A is 0.6 Mb.