Zu from the power supply of a 3rd generation TV. Schematic diagram of a switching power supply for a TV set

Sometimes it happens that the battery in the car runs out and it is no longer possible to start it, since the starter does not have enough voltage and, accordingly, current to crank the engine shaft. In this case, you can “light it” from another car owner so that the engine starts and the battery starts charging from the generator, but this requires special wires and a person willing to help you. You can also charge the battery yourself using a specialized charger, but they are quite expensive and you don’t have to use them very often. Therefore, in this article we will take a detailed look at the homemade device, as well as instructions on how to make a charger for a car battery with your own hands.

Homemade device

Normal battery voltage when disconnected from the vehicle is between 12.5 V and 15 V. Therefore, the charger must output the same voltage. The charge current should be approximately 0.1 of the capacity, it can be less, but this will increase the charging time. For a standard battery with a capacity of 70-80 Ah, the current should be 5-10 amperes, depending on the specific battery. Our homemade battery charger must meet these parameters. To assemble a charger for a car battery, we need the following elements:

Transformer. Any old electrical appliance or one purchased on the market with an overall power of about 150 watts is suitable for us, more is possible, but not less, otherwise it will get very hot and may fail. It’s great if the voltage of its output windings is 12.5-15 V and the current is about 5-10 amperes. You can view these parameters in the documentation for your part. If the required secondary winding is not available, then it will be necessary to rewind the transformer to a different output voltage. For this:

Thus, we found or assembled the ideal transformer to make our own battery charger.

We will also need:

Having prepared all the materials, you can proceed to the process of assembling the car charger itself.

Assembly technology

To make a charger for a car battery with your own hands, you need to follow the step-by-step instructions:

1. We create a homemade battery charging circuit. In our case it will look like this:
   
2. We use transformer TS-180-2. It has several primary and secondary windings. To work with it, you need to connect two primary and two secondary windings in series to obtain the desired voltage and current at the output.
   
   
3. Using a copper wire, we connect pins 9 and 9’ to each other.
   
4. On a fiberglass plate we assemble a diode bridge from diodes and radiators (as shown in the photo).
   
5. We connect pins 10 and 10’ to the diode bridge.
6. We install a jumper between pins 1 and 1’.
   
7. Using a soldering iron, attach a power cord with a plug to pins 2 and 2’.
8. We connect a 0.5 A fuse to the primary circuit, and a 10-amp fuse to the secondary circuit, respectively.
9. We connect an ammeter and a piece of nichrome wire into the gap between the diode bridge and the battery. One end of which is fixed, and the other must provide a moving contact, thus the resistance will change and the current supplied to the battery will be limited.
10. We insulate all connections with heat shrink or electrical tape and place the device in the housing. This is necessary to avoid electric shock.
11. We install a moving contact at the end of the wire so that its length and, accordingly, the resistance are maximum. And connect the battery. By decreasing or increasing the length of the wire, you need to set the desired current value for your battery (0.1 of its capacity).
12. During the charging process, the current supplied to the battery will itself decrease and when it reaches 1 ampere, we can say that the battery is charged. It is also advisable to directly monitor the voltage on the battery, but to do this it must be disconnected from the charger, since when charging it will be slightly higher than the actual values.

The first start-up of the assembled circuit of any power source or charger is always carried out through an incandescent lamp if it lights up at full intensity - either there is an error somewhere, or the primary winding is short-circuited! An incandescent lamp is installed in the gap of the phase or neutral wire feeding the primary winding.

This circuit of a homemade battery charger has one big drawback - it does not know how to independently disconnect the battery from charging after reaching the required voltage. Therefore, you will have to constantly monitor the readings of the voltmeter and ammeter. There is a design that does not have this drawback, but its assembly will require additional parts and more effort.

A visual example of the finished product

Operating rules

The disadvantage of a homemade charger for a 12V battery is that after the battery is fully charged, the device does not automatically turn off. That is why you will have to periodically glance at the scoreboard in order to turn it off in time. Another important nuance is that checking the charger for spark is strictly prohibited.

The material in this article is intended not only for owners of already rare televisions who want to restore their functionality, but also for those who want to understand the circuitry, structure and operating principle of switching power supplies. If you master the material in this article, you can easily understand any circuit and operating principle of switching power supplies for household appliances, be it a TV, laptop or office equipment. And so let's get started...

Soviet-made televisions, the third generation ZUSTST, used switching power supplies - MP (power module).

Switching power supplies, depending on the TV model where they were used, were divided into three modifications - MP-1, MP-2 and MP-3-3. The power modules are assembled according to the same electrical circuit and differ only in the type of pulse transformer and the voltage rating of capacitor C27 at the output of the rectifier filter (see circuit diagram).

Functional diagram and principle of operation of the switching power supply for the TV ZUSTST

Rice. 1. Functional diagram of the switching power supply for the ZUSTST TV:

1 - network rectifier; 2 - trigger pulse generator; 3 - pulse generator transistor, 4 - control cascade; 5 - stabilization device; 6 - protection device; 7 - pulse transformer of the TV power supply 3ust; 8 - rectifier; 9 - load

Let at the initial moment of time a pulse be generated in device 2, which will open the transistor of the pulse generator 3. At the same time, a linearly increasing sawtooth current will begin to flow through the winding of the pulse transformer with pins 19, 1. At the same time, energy will accumulate in the magnetic field of the transformer core, the value of which is determined by the open time of the pulse generator transistor. The secondary winding (pins 6, 12) of the pulse transformer is wound and connected in such a way that during the period of magnetic energy accumulation, a negative potential is applied to the anode of the VD diode and it is closed. After some time, control cascade 4 closes the pulse generator transistor. Since the current in the winding of transformer 7 cannot change instantly due to the accumulated magnetic energy, a self-induction emf of the opposite sign occurs. The VD diode opens, and the secondary winding current (pins 6, 12) increases sharply. Thus, if in the initial period of time the magnetic field was associated with the current that flowed through winding 1, 19, now it is created by the current of winding 6, 12. When all the energy accumulated during the closed state of switch 3 goes into the load, then in the secondary winding will reach zero.

From the above example we can conclude that by adjusting the duration of the open state of the transistor in a pulse generator, you can control the amount of energy that goes to the load. This adjustment is carried out using control cascade 4 using a feedback signal - the voltage at the terminals of winding 7, 13 of the pulse transformer. The feedback signal at the terminals of this winding is proportional to the voltage across the load 9.

If the voltage across the load decreases for some reason, the voltage supplied to the stabilization device 5 will also decrease. In turn, the stabilization device, through the control cascade, will begin to close the pulse generator transistor later. This will increase the time during which current will flow through winding 1, 19, and the amount of energy transferred to the load will accordingly increase.

The moment of the next opening of transistor 3 is determined by the stabilization device, where the signal coming from winding 13, 7 is analyzed, which allows you to automatically maintain the average value of the output DC voltage.

The use of a pulse transformer makes it possible to obtain voltages of different amplitudes in the windings and eliminates the galvanic connection between the circuits of secondary rectified voltages and the supply electrical network. Control stage 4 determines the range of pulses created by the generator and, if necessary, turns it off. The generator is switched off when the mains voltage drops below 150 V and the power consumption drops to 20 W, when the stabilization cascade stops functioning. When the stabilization cascade is not working, the pulse generator becomes uncontrollable, which can lead to the appearance of large current pulses in it and to the failure of the pulse generator transistor.

Schematic diagram of a switching power supply for a ZUSTST TV

Let's look at the circuit diagram of the MP-3-3 power module and the principle of its operation.

Rice. 2 Schematic diagram of a switching power supply for a ZUSTST TV, module MP-3-3

It includes a low-voltage rectifier (diodes VD4 - VD7), a trigger pulse shaper (VT3), a pulse generator (VT4), a stabilization device (VT1), a protection device (VT2), a pulse transformer T1 of the 3ustst power supply and rectifiers using diodes VD12 - VD15 with voltage stabilizer (VT5 - VT7).

The pulse generator is assembled according to a blocking generator circuit with collector-base connections on a VT4 transistor. When you turn on the TV, the constant voltage from the output of the low-voltage rectifier filter (capacitors C16, C19 and C20) through winding 19, 1 of transformer T1 is supplied to the collector of transistor VT4. At the same time, the mains voltage from diode VD7 through capacitors C11, C10 and resistor R11 charges capacitor C7, and also goes to the base of transistor VT2, where it is used in the device for protecting the power module from low voltage. When the voltage on capacitor C7 applied between the emitter and base 1 of unijunction transistor VT3 reaches 3 V, transistor VT3 will open. Capacitor C7 is discharged through the circuit: emitter-base junction 1 of transistor VT3, emitter junction of transistor VT4, parallel connected, resistors R14 and R16, capacitor C7.

The discharge current of capacitor C7 opens transistor VT4 for a time of 10 - 15 μs, sufficient for the current in its collector circuit to increase to 3...4 A. The flow of collector current of transistor VT4 through the magnetization winding 19, 1 is accompanied by the accumulation of energy in the magnetic field of the core. After capacitor C7 has finished discharging, transistor VT4 closes. The cessation of the collector current causes the appearance of a self-induction EMF in the coils of transformer T1, which creates positive voltages at terminals 6, 8, 10, 5 and 7 of transformer T1. In this case, current flows through the diodes of half-wave rectifiers in the secondary circuits (VD12 - VD15).

With a positive voltage at terminals 5, 7 of transformer T1, capacitors C14 and C6 are charged, respectively, in the anode and control electrode circuits of thyristor VS1 and C2 in the emitter-base circuit of transistor VT1.

Capacitor C6 is charged through the circuit: pin 5 of transformer T1, diode VD11, resistor R19, capacitor C6, diode VD9, pin 3 of the transformer. Capacitor C14 is charged through the circuit: pin 5 of transformer T1, diode VD8, capacitor C14, pin 3 of transformer. Capacitor C2 is charged through the circuit: pin 7 of transformer T1, resistor R13, diode VD2, capacitor C2, pin 13 of the transformer.

The subsequent switching on and off of the blocking generator transistor VT4 is carried out similarly. Moreover, several such forced oscillations are sufficient to charge the capacitors in the secondary circuits. With the completion of charging of these capacitors, positive feedback begins to operate between the windings of the blocking generator connected to the collector (pins 1, 19) and the base (pins 3, 5) of the VT4 transistor. In this case, the blocking generator goes into self-oscillation mode, in which transistor VT4 will automatically open and close at a certain frequency.

During the open state of transistor VT4, its collector current flows from the plus of electrolytic capacitor C16 through the winding of transformer T1 with terminals 19, 1, the collector and emitter junctions of transistor VT4, parallel connected resistors R14, R16 to the minus of capacitor C16. Due to the presence of inductance in the circuit, the collector current increases according to a sawtooth law.

To eliminate the possibility of failure of transistor VT4 from overload, the resistance of resistors R14 and R16 is selected in such a way that when the collector current reaches 3.5 A, a voltage drop is created across them sufficient to open thyristor VS1. When the thyristor opens, capacitor C14 is discharged through the emitter junction of transistor VT4, resistors R14 and R16 connected in parallel, and open thyristor VS1. The discharge current of capacitor C14 is subtracted from the base current of transistor VT4, which leads to its premature closing.

Further processes in the operation of the blocking generator are determined by the state of the thyristor VS1, the earlier or later opening of which allows you to regulate the rise time of the sawtooth current and thereby the amount of energy stored in the transformer core.

The power module can operate in stabilization and short circuit mode.

The stabilization mode is determined by the operation of the DC amplifier (DC amplifier) ​​assembled on transistor VT1 and thyristor VS1.

At a network voltage of 220 Volts, when the output voltages of the secondary power supplies reach rated values, the voltage on the winding of transformer T1 (pins 7, 13) increases to a value at which the constant voltage at the base of the transistor VT1, where it is supplied through the divider Rl - R3, becomes more negative than at the emitter, where it is completely transmitted. Transistor VT1 opens along the circuit: pin 7 of the transformer, R13, VD2, VD1, emitter and collector junctions of transistor VT1, R6, control electrode of the thyristor VS1, R14, R16, pin 13 of the transformer. This current, summed with the initial current of the control electrode of the thyristor VS1, opens it at the moment when the output voltage of the module reaches the nominal values, stopping the increase in the collector current.

By changing the voltage at the base of transistor VT1 with trimming resistor R2, you can adjust the voltage across resistor R10 and, therefore, change the opening moment of thyristor VS1 and the duration of the open state of transistor VT4, thereby setting the output voltage of the power supply.

When the load decreases (or the network voltage increases), the voltage at terminals 7, 13 of transformer T1 increases. At the same time, the negative voltage at the base increases in relation to the emitter of transistor VT1, causing an increase in the collector current and a voltage drop across resistor R10. This leads to earlier opening of thyristor VS1 and closing of transistor VT4. This reduces the power supplied to the load.

When the network voltage decreases, the voltage on the winding of transformer T1 and the base potential of transistor VT1 relative to the emitter become correspondingly lower. Now, due to a decrease in the voltage created by the collector current of transistor VT1 on resistor R10, thyristor VS1 opens at a later time and the amount of energy transferred to the secondary circuits increases. An important role in protecting transistor VT4 is played by the cascade on transistor VT2. When the network voltage decreases below 150 V, the voltage on the winding of transformer T1 with terminals 7, 13 is insufficient to open transistor VT1. In this case, the stabilization and protection device does not work, transistor VT4 becomes uncontrollable and the possibility of its failure is created due to exceeding the maximum permissible values ​​of voltage, temperature, and current of the transistor. To prevent the failure of transistor VT4, it is necessary to block the operation of the blocking generator. The transistor VT2 intended for this purpose is connected in such a way that a constant voltage is supplied to its base from the divider R18, R4, and a pulsating voltage with a frequency of 50 Hz is supplied to the emitter, the amplitude of which is stabilized by the zener diode VD3. When the network voltage decreases, the voltage at the base of transistor VT2 decreases. Since the voltage at the emitter is stabilized, a decrease in the voltage at the base causes the transistor to open. Through the open transistor VT2, trapezoidal-shaped pulses from the diode VD7 arrive at the control electrode of the thyristor, opening it for a time determined by the duration of the trapezoidal pulse. This causes the blocking generator to stop working.

Short circuit mode occurs when there is a short circuit in the load of secondary power supplies. In this case, the power supply is started by triggering pulses from the trigger device assembled on transistor VT3, and turned off using thyristor VS1 according to the maximum collector current of transistor VT4. After the end of the triggering pulse, the device is not excited, since all the energy is spent in the short-circuited circuit.

After the short circuit is removed, the module enters stabilization mode.

Pulse voltage rectifiers connected to the secondary winding of transformer T1 are assembled using a half-wave circuit.

The VD12 diode rectifier creates a voltage of 130 V to power the horizontal scanning circuit. The ripples of this voltage are smoothed out by the electrolytic capacitor C27. Resistor R22 eliminates the possibility of a significant increase in voltage at the rectifier output when the load is turned off.

A 28 V rectifier is assembled on the VD13 diode, designed to power the vertical scanning of a TV. Voltage filtering is provided by capacitor C28 and inductor L2.

A 15 V voltage rectifier for powering an audio amplifier is assembled using a VD15 diode and a SZO capacitor.

The 12 V voltage used in the color module (MC), radio channel module (MRK) and vertical scanning module (MS) is created by a rectifier based on diode VD14 and capacitor C29. At the output of this rectifier, a compensation voltage regulator assembled on transistors is included. It consists of a regulating transistor VT5, a current amplifier VT6 and a control transistor VT7. The voltage from the output of the stabilizer through the divider R26, R27 is supplied to the base of the transistor VT7. Variable resistor R27 is designed to set the output voltage. In the emitter circuit of transistor VT7, the voltage at the output of the stabilizer is compared with the reference voltage at the zener diode VD16. The voltage from the collector VT7 through the amplifier on the transistor VT6 is supplied to the base of the transistor VT5, connected in series to the rectified current circuit. This leads to a change in its internal resistance, which, depending on whether the output voltage has increased or decreased, either increases or decreases. Capacitor C31 protects the stabilizer from excitation. Through resistor R23, voltage is supplied to the base of transistor VT7, which is necessary to open it when turned on and restore it after a short circuit. Choke L3 and capacitor C32 are an additional filter at the output of the stabilizer.

Capacitors C22 - C26 bypass rectifier diodes to reduce interference emitted by pulsed rectifiers into the electrical network.

Surge filter for power supply unit ZUSTST

The PFP power filter board is connected to the electrical network via connector X17 (A12), switch S1 in the TV control unit and mains fuses FU1 and FU2.

VPT-19 type fuses are used as mains fuses, the characteristics of which make it possible to provide significantly more reliable protection of television receivers in the event of malfunctions than PM type fuses.

The purpose of the barrier filter is .

On the power filter board there are barrier filter elements (C1, C2, SZ, inductor L1) (see circuit diagram).

Resistor R3 is designed to limit the current of the rectifier diodes when the TV is turned on. The posistor R1 and resistor R2 are elements of the kinescope mask demagnetization device.

The article discusses several options for assembling a power supply and charger with your own hands.

Power supply + 12V charger made from scrap materials

The simplest power supply should simply convert 220V alternating current to 12V direct current. The first task (lowering the voltage) is performed using a step-down transformer of any origin, the second (replacing alternating current with direct current) using a diode bridge and a capacitor.

Accordingly, the circuit diagram of the simplest power supply looks like this:

Let's look at the necessary details one by one. Any step-down transformer with sufficient power can be used as a transformer. The latter depends on the tasks that you assign to the planned power supply; 10-20 W is enough to charge car batteries. Since partial loss of voltage is almost inevitable, to ensure stable operation of the device, the secondary winding must provide a voltage of 14-20 volts (optimally 16-18V).

The easiest way to find a suitable transformer is in a radio parts store or at the nearest radio flea market. It might be a good idea to look in the attic - this type of converter is used in audio recorders, game consoles, and office computer equipment. If you have a transformer with an inappropriate voltage (for example, 24V), you can change the parameters of the secondary winding or use resistors.

The simplest diode bridge is assembled from four identical diodes, which as a result will serve as a full-wave rectifier.

A capacitor is necessary to avoid dips and one thing can be said with confidence: the larger the capacitance, the better. You can use a 16-volt one with 1000 uF or more.

The assembly order is as follows:

— assembling the diode bridge;

— connect a transformer to it;

— connect the capacitor to the free outputs of the diode bridge, observing the polarity;

— remove the power connector from the capacitor.

You can pack it all in a beautiful box and tie it with a beautiful ribbon.

The proposed circuit is primitive and has many disadvantages, so there are many more complex options, for example, with the ability to adjust the output voltage and current, using a variety of protective systems (from overheating, from voltage surges, current), volt-ampere meters and other things.

Let's look at these schemes in more detail using specific examples of building a battery charger.

Example 1 Assembling a charger based on a power supply from a Kenon printer.

For this we need:

— the power supply itself;

- volt-amperemeter;

— variable resistors (3 pcs);

— cooler of any origin;

- power button;

- voltage regulators on the chip (LM 2596 or equivalent);

— output connectors;

- bolts, nuts and other fasteners.

The printer power supply is well suited because it has sufficient power and reliability, and, importantly, has a built-in voltage regulation board. Therefore, if you need a power source of a strictly specified voltage, you just need to find the right microcircuit (in this case, TL431) and select the right resistor to replace the original one.

We will try to assemble a unit with the ability to change the operating voltage in the range 0-30V, the circuit diagram of which is shown in the figure:

Procedure:

Since the ceiling of the required operating voltage is higher than the inherent voltage of the printer unit, you need to “raise the bar.” To do this, we replace the resistor on the board mentioned above.

We take the body of the future charger and make holes in the front part for three resistors, a volt-ampere meter and a power button

We mount everything listed on the panel

Similarly, we make holes in the back cover for the cooler, output connectors and power plug (we transfer it from the printer unit body)

Mounting the back panel

We mount the internals - the main board of the printer power supply, voltage regulators

We assemble an electrical circuit. We connect one converter to the cooler and a voltmeter, it should be adjusted to 12V. The second makes it possible to adjust the current strength. We connect two resistors (10 and 1 kOhm, respectively) in series, as a result we get the ability to accurately regulate the voltage, the third limits the current in the range from 0 to 3A.

We assemble the case, do a test run, and use it.

Example 2. Assembling a thyristor charger

This type of charging is based on a network transformer with an adjusted output voltage (18-20V) and a current pulse generator on a thyristor. In this case, the driving pulses are generated by transistors, and the thyristor only passes the generated pulse to the battery.

Schematic diagram in the figure

It is best to use diodes at 10 amperes, a capacitor of at least 1000 microfarads at 40V. Using lower voltage and capacitance capacitors is risky as it may result in unstable and short-lived service. The cooler is extremely important, since charging the battery takes a fair amount of time and the transformer can heat up, so it is better to use a good performance fan (from an old computer, laptop, electric welder) and place it in the front part (this will provide maximum airflow to the inside of the case). The housing can be selected or made from sheet metal/plastic.

Example 3 Another charger for particularly sophisticated radio amateurs.

The proposed design ensures automatic cutting off of the current supplied to the battery when it reaches full charge.

Schematic diagram in the figure:

Features of this device:

- despite its simplicity, it requires the use of a special printed circuit board;

— the thyristor is used not only as a switch, but also as a rectifier;

Every car owner needs a battery charger, but it costs a lot, and regular preventive trips to a car service center are not an option. Battery service at a service station takes time and money. In addition, with a discharged battery, you still need to drive to the service station. Anyone who knows how to use a soldering iron can assemble a working charger for a car battery with their own hands.

A little theory about batteries

Any battery is a storage device for electrical energy. When voltage is applied to it, energy is stored due to chemical changes inside the battery. When a consumer is connected, the opposite process occurs: a reverse chemical change creates voltage at the terminals of the device, and current flows through the load. Thus, in order to get voltage from the battery, you first need to “put it down,” that is, charge the battery.

Almost any car has its own generator, which, when the engine is running, provides power to the on-board equipment and charges the battery, replenishing the energy spent on starting the engine. But in some cases (frequent or difficult engine starts, short trips, etc.) the battery energy does not have time to be restored, and the battery is gradually discharged. There is only one way out of this situation - charging with an external charger.

How to find out the battery status

To decide whether charging is necessary, you need to determine the state of the battery. The simplest option - “turns/does not turn” - is at the same time unsuccessful. If the battery “doesn’t turn”, for example, in the garage in the morning, then you won’t go anywhere at all. The “does not turn” condition is critical, and the consequences for the battery can be dire.

The optimal and reliable method for checking the condition of a battery is to measure the voltage on it with a conventional tester. At an air temperature of about 20 degrees dependence of the degree of charge on voltage on the terminals of the battery disconnected from the load (!) is as follows:

• 12.6…12.7 V - fully charged;
• 12.3…12.4 V - 75%;
• 12.0…12.1 V - 50%;
• 11.8…11.9 V - 25%;
• 11.6…11.7 V - discharged;
• below 11.6 V - deep discharge.

It should be noted that the voltage of 10.6 volts is critical. If it drops below, the “car battery” (especially a maintenance-free one) will fail.

Correct charging

There are two methods of charging a car battery - constant voltage and constant current. Everyone has their own features and disadvantages:

Homemade battery chargers

Assembling a charger for a car battery with your own hands is realistic and not particularly difficult. To do this, you need to have basic knowledge of electrical engineering and be able to hold a soldering iron in your hands.

Simple 6 and 12 V device

This scheme is the most basic and budget-friendly. Using this charger, you can efficiently charge any lead-acid battery with an operating voltage of 12 or 6 V and an electrical capacity of 10 to 120 A/h.

The device consists of a step-down transformer T1 and a powerful rectifier assembled using diodes VD2-VD5. The charging current is set by switches S2-S5, with the help of which quenching capacitors C1-C4 are connected to the power circuit of the primary winding of the transformer. Thanks to the multiple “weight” of each switch, various combinations allow you to stepwise adjust the charging current in the range of 1–15 A in 1 A increments. This is enough to select the optimal charging current.

For example, if a current of 5 A is required, then you will need to turn on the toggle switches S4 and S2. Closed S5, S3 and S2 will give a total of 11 A. To monitor the voltage on the battery, use a voltmeter PU1, the charging current is monitored using an ammeter PA1.

The design can use any power transformer with a power of about 300 W, including homemade ones. It should produce a voltage of 22–24 V on the secondary winding at a current of up to 10–15 A. In place of VD2-VD5, any rectifier diodes that can withstand a forward current of at least 10 A and a reverse voltage of at least 40 V are suitable. D214 or D242 are suitable. They should be installed through insulating gaskets on a radiator with a dissipation area of ​​at least 300 cm2.

Capacitors C2-C5 must be non-polar paper with an operating voltage of at least 300 V. Suitable, for example, are MBChG, KBG-MN, MBGO, MBGP, MBM, MBGCh. Similar cube-shaped capacitors were widely used as phase-shifting capacitors for electric motors in household appliances. A DC voltmeter of type M5−2 with a measurement limit of 30 V was used as PU1. PA1 is an ammeter of the same type with a measurement limit of 30 A.

The circuit is simple, if you assemble it from serviceable parts, then it does not need adjustment. This device is also suitable for charging six-volt batteries, but the “weight” of each of the switches S2-S5 will be different. Therefore, you will have to navigate the charging currents using an ammeter.

With continuously adjustable current

Using this scheme, it is more difficult to assemble a charger for a car battery with your own hands, but it can be repeated and also does not contain scarce parts. With its help, it is possible to charge 12-volt batteries with a capacity of up to 120 A/h, the charge current is smoothly regulated.

The battery is charged using a pulsed current; a thyristor is used as a regulating element. In addition to the knob for smoothly adjusting the current, this design also has a mode switch, when turned on, the charging current doubles.

The charging mode is controlled visually using the RA1 dial gauge. Resistor R1 is homemade, made of nichrome or copper wire with a diameter of at least 0.8 mm. It serves as a current limiter. Lamp EL1 is an indicator lamp. In its place, any small-sized indicator lamp with a voltage of 24–36 V will do.

A step-down transformer can be used ready-made with an output voltage on the secondary winding of 18–24 V at a current of up to 15 A. If you don’t have a suitable device at hand, you can make it yourself from any network transformer with a power of 250–300 W. To do this, wind all windings from the transformer except the mains winding, and wind one secondary winding with any insulated wire with a cross-section of 6 mm. sq. The number of turns in the winding is 42.

Thyristor VD2 can be any of the KU202 series with the letters V-N. It is installed on a radiator with a dispersion area of ​​at least 200 sq. cm. The power installation of the device is done with wires of minimal length and with a cross-section of at least 4 mm. sq. In place of VD1, any rectifier diode with a reverse voltage of at least 20 V and withstanding a current of at least 200 mA will work.

Setting up the device comes down to calibrating the RA1 ammeter. This can be done by connecting several 12-volt lamps with a total power of up to 250 W instead of a battery, monitoring the current using a known-good reference ammeter.

From a computer power supply

To assemble this simple charger with your own hands, you will need a regular power supply from an old ATX computer and knowledge of radio engineering. But the characteristics of the device will be decent. With its help, batteries are charged with a current of up to 10 A, adjusting the current and charge voltage. The only condition is that the power supply is desirable on the TL494 controller.

For creating DIY car charging from a computer power supply you will have to assemble the circuit shown in the figure.

Step by step steps required to finalize the operation will look like this:

1. Bite off all the power bus wires, with the exception of the yellow and black ones.
2. Connect the yellow and separately black wires together - these will be the “+” and “-” chargers, respectively (see diagram).
3. Cut all traces leading to pins 1, 14, 15 and 16 of the TL494 controller.
4. Install variable resistors with a nominal value of 10 and 4.4 kOhm on the power supply casing - these are the controls for regulating the voltage and charging current, respectively.
5. Using a suspended installation, assemble the circuit shown in the figure above.

If the installation is done correctly, then the modification is complete. All that remains is to equip the new charger with a voltmeter, an ammeter and wires with alligator clips for connecting to the battery.

In the design it is possible to use any variable and fixed resistors, except for the current resistor (the lower one in the circuit with a nominal value of 0.1 Ohm). Its power dissipation is at least 10 W. You can make such a resistor yourself from a nichrome or copper wire of the appropriate length, but you can actually find a ready-made one, for example, a 10 A shunt from a Chinese digital tester or a C5-16MV resistor. Another option is two 5WR2J resistors connected in parallel. Such resistors are found in switching power supplies for PCs or TVs.

What you need to know when charging a battery

When charging a car battery, it is important to follow a number of rules. This will help you Extend battery life and maintain your health:

The question of creating a simple battery charger with your own hands has been clarified. Everything is quite simple, all you have to do is stock up on the necessary tools and you can safely get to work.

It is often necessary to “power” an amateur radio structure with 12 volts in domestic conditions. Switching power supplies from old third-generation TVs (see Fig. 3.14) of the Slavutich-Ts202, Raduga-Ts257, Chaika-Ts280D and similar models come to the rescue.

Their circuit design is, as a rule, universal; such a power supply will provide an output voltage of 12 V with a useful current of up to 0.8 A.

The output voltage is removed from the contacts:

2 - 135 V (for horizontal scanning);

Contacts 1, 3, 6 of connector X2 (AZ) - as it is designated on the board and in the electrical diagram - are combined and connected to the “common wire”. In Fig. Figure 3.15 shows a schematic diagram of the MP-3-3 power module (similar to the MP-3-1 module used in some models of color TVs of the ZUSTST-61-1 type series).

Rice. 3.14. Type of TV power module

Fig, 3.15. Electrical circuit of the MP-3-3 module

The power cord to the 220 V network is connected to connector XI.

The main difference between these “related” units is in the indicators: the more “fresh” MP-3-3 has an AL307BM LED indicator, and the older version has an INS-1 gas-discharge lamp - through a 135 V power supply limiting resistor. If these indicators after supplying power to a known-good MP-3, they do not light up (which often happens without a connected load), which means that the power module needs to be started artificially. To do this, it is often enough to connect between contacts 1 and 2 (135 V output) an equivalent load - a constant resistor of the MLT-1 type with a resistance of 6.8 kOhm ±30%. After such modification, the pulse generator “starts up”, transformer T1 begins to “sing” quietly, and the power module is ready to operate across the entire spectrum of output voltages. With resistor R27 (designation on the diagram and on the board), you can adjust the voltage at the 12 V output within small limits. There is no need to install additional filtering oxide capacitors (at the output), the shape of the output voltage on the oscilloscope screen has a clear straight line, not burdened by interference.

The most likely cause of failures of these power modules “lies” in a malfunction of the KT838 (VT4) blocking generator transistor. The electrical diagram (Fig. 3.15) shows the values ​​of the control voltages at various points, so it will not be difficult for any radio amateur to repair such a power supply. And the elements for repair can be found in the “bins”, without spending material resources on the purchase of new radio components, as would inevitably have to be done when repairing more compact, but often more “capricious” pulse adapters for modern radio equipment. In this, undoubtedly, “morally obsolete” power modules of the MP-3 type (various modifications) outperform more modern ones, so it is too early to write off the former.

Literature: Kashkarov A.P. Electronic devices for coziness and comfort.