Charger(ZU) for the battery is necessary for every motorist, but it costs a lot, and regular preventive trips to a car service are not an option. Servicing a battery in a workshop takes time and money. In addition, on a discharged battery, you still need to get to the service. Assemble a workable charger with your own hands for car battery anyone who knows how to use a soldering iron can do it with their own hands.

Some battery theory

Any battery (battery) is a store of electrical energy. When voltage is applied to it, energy accumulates due to chemical changes inside the battery. When the consumer is connected, the opposite process occurs: the reverse chemical change creates voltage at the terminals of the device, current flows through the load. Thus, in order to receive voltage from the battery, it must first be “put”, i.e., charge the battery.

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

How to check battery status

To decide on the need for charging, you need to determine the state of the battery. The simplest option - "twists / does not twist" - at the same time is unsuccessful. If the battery "does not turn", for example, in the morning in the garage, then you will not go anywhere at all. The “not spinning” condition is critical, and the consequences for the battery can be sad.

The best and most 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 the voltage on the terminals of the battery disconnected from the load (!) The following:

• 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, then the "car battery" (especially maintenance-free) will fail.

Proper 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 real and not very difficult. To do this, you need to have basic knowledge of electrical engineering and be able to hold a soldering iron in your hands.

A simple device for 6 and 12 V

Such a scheme is the most elementary and budgetary. With this charger, you can charge any lead-acid battery with an operating voltage of 12 or 6 V and an electric capacity of 10 to 120 A/h.

The device consists of a step-down transformer T1 and a powerful rectifier assembled on 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 supply circuit of the primary winding of the transformer. Due to the multiple "weight" of each switch, various combinations allow you to stepwise adjust the charging current within 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 needed, 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. A voltmeter PU1 is used to control the voltage on the battery, the charging current is monitored using an ammeter PA1.

In the design, you can use any power transformer with a power of about 300 W, including a home-made one. It should produce a voltage of 22–24 V at a current of up to 10–15 A on the secondary winding. 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 will do. D214 or D242 will do. They should be installed through insulating gaskets on a radiator with a scattering area of ​​​​at least 300 cm2.

Capacitors C2-C5 must be non-polar paper with an operating voltage of at least 300 V. For example, MBCHG, KBG-MN, MBGO, MBGP, MBM, MBGCH are suitable. Similar cube-shaped capacitors were widely used as phase-shifters for electric motors. household appliances. A voltmeter is used as PU1 direct current type M5−2 with a measurement limit of 30 V. 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 to be adjusted. 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 in the charging currents by the ammeter.

Continuously adjustable current

According to 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 permissible to charge 12-volt batteries with a capacity of up to 120 A / h, the charge current is smoothly adjustable.

The battery is charged by a pulsed current, a thyristor is used as a regulating element. In addition to the smooth current adjustment knob, this design also has a mode switch, when turned on, the charging current is doubled.

The charging mode is controlled visually by the pointer device RA1. 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 - indicator. 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 through the secondary winding of 18–24 V at a current of up to 15 A. If there was no suitable device at hand, then you can make it yourself from any network transformer with a power of 250–300 W. To do this, all windings are wound from the transformer, except for the mains winding, and one secondary winding is wound 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 letters V-N. It is installed on a radiator with a dispersion area of ​​​​at least 200 cm2. The power installation of the device is made with wires of minimum 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 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, controlling 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 on the other hand, the characteristics of the device will turn out to be decent. With its help, batteries are charged with a current of up to 10 A, adjusting the current and voltage of the charge. The only condition is that the PSU is desirable on the TL494 controller.

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

Step-by-step operations necessary for finalization will look like this:

1. Bite off all the wires of the power buses, except for the yellow and black ones.
2. Connect the yellow and black wires separately - these will be the “+” and “-” memory, 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 casing of the power supply unit - these are the voltage and current adjustment bodies, respectively.
5. Hinged mounting to assemble the circuit shown in the figure above.

If the installation is done correctly, then the revision is completed. It remains to equip the new charger with a voltmeter, ammeter and wires with "crocodiles" for connecting to the battery.

It is possible to use any variable and fixed resistors in the design, except for the current one (the lower one according to the circuit with a nominal value of 0.1 Ohm). Its power dissipation is at least 10 watts. You can make such a resistor yourself from nichrome or copper wire of the appropriate length, but it’s also possible to find a ready-made one, for example, a shunt from a Chinese digital tester for 10 A or a C5-16MV resistor. Another option is two 5WR2J resistors connected in parallel. Such resistors are 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 prolong battery life and keep your health:

The question of creating a simple do-it-yourself battery charger has been clarified. Everything is quite simple, it remains to stock up on the necessary tools and you can safely get to work.

When using acid batteries in a vehicle or systems uninterruptible power supply, they need to be charged, preferably in automatic mode. Of course, charging should be provided by the device manufacturer. Fully provide the necessary modes for continuous operation and good condition of the battery installed in it. However, there are situations when there is a need for additional charge and battery maintenance:
1. Such situations arise in the cold season, when the car is in the garage for a long time and the battery loses its charge. It happens that the driver did not turn off the consumers and the next day the car does not start.
2. In UPS systems, the situation is much better. The device constantly monitors the battery charge, charges it correctly and does not allow it to be discharged more than necessary. Until an inquisitive mind gets into it, to improve performance.
My case went according to the second scenario.

Once, in winter, the situation with energy supply deteriorated sharply. It soon became clear that this was for a long time, and I took out an uninterruptible power supply. It had a 7 A / H battery, which was hardly enough for a ten-watt lighting LED. The light was turned off for 2-4 hours, sometimes there was no electricity even for 6 hours. The electricity was turned on several times during the day for two hours, but he did not have time to charge. Yes, and I wanted to watch TV, because the 220 V. output was idle.
Later, I bought a 75 A / H used battery, and took care of charging it. It was necessary to charge it quickly and without supervision by people. Moreover, the charger should be cheap and good.
I canceled the transformer immediately, since the mains voltage varied widely, sometimes dropping to 140 V. I had an inexpensive Chinese switching power supply 12 V., 60 W, called "S 60-12". However, it will not be difficult to purchase one in an online store or in a local lighting store.
The block has excellent main features:

Input voltage	85 - 264 V. (AC)
Output voltage	10.8 - 13.2 V. (DC)
Output current	0 - 5A

After connecting to the battery, troubles began to arise:
1. 13.2V voltage is not enough to charge
2. very large current when the battery voltage is low
3. Discharging the battery in the power supply

Consider the output circuits of our block, and determine what can be done to solve problems:
1. You can increase the output voltage by shunting the resistor from the TL431 control output to the common wire (R15, SVR1)
2. The current can be reduced by installing a large current-limiting resistor at the output, or by reducing the output voltage
3. Discharge of the battery is eliminated by a series diode

I had a weak 7 Ah battery, for which the discharge to the power supply (~ 50 mA) was significant, and I installed a bunch of diodes in series with the UPS output. Later, he abandoned diodes when he switched to a large battery.
First you need to increase the output voltage by installing a 12 kΩ resistor in parallel with R15 (see the first figure). After that, the maximum voltage at the output of the UPS will be 16 V., without taking into account the drop on the diodes. The current limiting resistor is made of thick nichrome wire. In the absence of such, you can buy a ready-made resistor. The voltage should be set at the output terminals after the diode, loaded on the lighting lamp, to take into account the drop on the diode assembly. The table shows the nominal resistance (R) and the maximum power dissipation (Pmax) of the resistor, for a charge voltage of 13.8 V. (Umax), a minimum battery voltage of 11 V. (Umin) and a maximum charge current of 20% of the capacity (s) . This safe mode, since the current will fall linearly as it charges. You can independently calculate the resistance of the resistor:

R=(Umax-Umin)/0.2*s,

and the maximum power on it:

Pmax=(Umax-Umin) 2 /R

In general, the system turned out to be reliable, not requiring maintenance, but also with disadvantages. Of course, a resistor that shamelessly heats up at high currents. Long charging and the impossibility of a full charge.
After acquiring a 75 A/H battery and operating it in constant TV viewing mode (plus a 2 * 5W sound amplifier, T2 tuner, modem with a router, phone / tablet charging, lighting), the resistive circuit no longer had time to restore the wasted charge.

A switching power supply (UPS) stabilizes the output voltage using a controlled Zener diode SHR1 TL431, part of the output circuit diagram is shown in the first figure. The opening of this zener diode occurs when the voltage at the control output exceeds 2.5V. We can say that in normal mode, the voltage at this point is always 2.5 V. Our circuit will act on this pin to change the output voltage. Please note that the output voltage range of this UPS is limited. It is not desirable to increase the output voltage more than 16 V., and when it drops below 10 V., it turns off and attempts to start. It means that A battery discharged below 10V will not be able to charge with this charger. Just as this charger cannot be used as a laboratory PSU, due to the impossibility of adjusting the output voltage over a wide range and stabilizing the current in the event of a short circuit.

On the hastily a current stabilization circuit was assembled and the diode was excluded. The design and scheme are presented below:

The presented scheme has several shortcomings.
1. The inability to quickly adjust the current
2. Poor accuracy of current stabilization, depending on its level and output voltage
3. Lack of indication of the end of the process, for quick charge car batteries

The circuit worked for 4 months without malfunctions. The only maintenance is constantly rotting wires on the battery terminals (did not connect securely)

Now that the need for battery power has disappeared and free time has appeared, I decided to improve the device. Current regulation by an external variable resistor was introduced. Added an error amplifier to improve accuracy. Introduced LED indication of the operating mode.

ATTENTION - additional soldering of the resistor that increases the output voltage of the UPS, in this version of the control circuit is not required. Its function is performed by R10

As a result, the circuit diagram has become slightly more complicated. The second op amp, IC1B, operates as an integrator/error amplifier, comparing the voltage at the output of IC1A, which is proportional to the output current, with the reference voltage at RES.2 set by the regulator. At its output (pin 7 of IC1B), the voltage can be in two states. Near zero, when the current cannot reach the value set by the resistor. And, about 3.5 V., when the output current is captured and stabilized, that is, there is a charge. The "Charge" LED connected to the LED point indicates the state of the device. A VR1 TL431 zener parallel regulator provides a reference voltage for the current regulator resistor. At its cathode, the voltage should be 2.5 V. Two resistors R7, R8 instead of one are installed to reduce the power dissipation on them.
The value of the shunt resistance (Rsh), together with the gain IC1A (k) and the voltage at the point RES.1 (Vref), determine the maximum value of the charging current (Imax) of the regulator:

Imax=Vref/(k*Rsh).

Where is the gain of the differential amplifier:

k=R5/R1, with R1=R2, R5=R3.

In our case:

Rsh=0.1 ohm/3=0.0333 ohm,
k=1500 ohm/100 ohm=15,
Imax \u003d 2.5 V / (15 * 0.0333 Ohm) \u003d 5 A.

After checking the correct installation of the control board, you need to correctly connect it to the UPS. I tried to depict clearly, so that there would be no problems in connection. The control wire should be connected to the disassembled unit, having previously disconnected it from the 220 V network.!! Before turning on, it is necessary to install the PSU casing in its regular place and set the resistor R10 to the maximum high resistance. Turn on. set the output voltage of the UPS to work as part of an uninterruptible power supply, with open contacts of the "Mode" button, resistor SVR1 (see first figure) at the level of 13-13.8 V. When you press the "Mode" button, you should set the output voltage to 14 .4 V. resistor R10, for a single battery charge. We check the voltage at the extreme terminals of the adjustment resistor, it should be 2.5 V. By connecting a working battery, we will check the adjustment of the output current. The maximum current must not exceed 5A for this UPS. If the current is not sufficient, you need to change the gain of the amplifier to IC1A. However, after this amplifier, you can put a tuning resistor on a common wire and connect the engine of this resistor to 5 pins. IC1. to adjust the maximum. The minimum will be about zero amperes and does not need to be adjusted. A powerful resistor or hot plate coil can be used to test the output current, but the current will only stabilize over a small voltage range of approximately 10 V to 13 or 14.4 V, depending on the switch settings.

The charger has features:
- When charging up to 14.4 V., it is necessary to observe the state of the "Charge" LED. At the end of the charge, it will go out, and the charger should be disconnected from the battery.
- In the event of a battery failure and the voltage on it is less than 10 V., the LED will flash, but there will be no charge.
- If the output terminals are short-circuited, there will be no LED indication, but the internal protection of the UPS will work.
- This charger has no protection against polarity reversal of the battery terminals and it is advisable to install a 5 A fuse at the output.

The design of the control unit is made on a breadboard printed circuit board output components. The scheme uses widely used elements. Instead of the zener diode VR1, you can use an ordinary zener diode for a voltage of 3.3-5.1 V. (Vref) by changing the coefficient. gain diff. amplifier according to the above formula. An ultra-bright red LED in a transparent case, such LEDs shine well at low current. Variable regulator resistor of any convenient type with a nominal value of 1-10 kOhm.
As a current shunt, I used 0.1 ohm 1 W resistors, they are quite common and not in short supply. The connection to the shunt was made as shown in the figure and photograph. You can use a ready-made shunt or low resistance resistors 0.03-0.01 Ohm with a power of 3 or more watts, for example MPR-5W, BPR56. In extreme cases, you can use a coil of low-section copper wire, but the parameters will change with warming up.

List of radio elements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
IC1	Operational amplifier	LM358	1			To notepad
D1	rectifier diode	1N4148	1	KD521, KD522		To notepad
VR1	Reference IC	TL431	1			To notepad
R10	Trimmer resistor	50 kOhm	1	multi-turn		To notepad
R1, R2	Resistor	100 ohm	2	MLT-0.125		To notepad
R3, R5	Resistor	1.5 kOhm	2	MLT-0.125		To notepad
R4	Resistor	22 kOhm	1	MLT-0.125		To notepad
R6	Resistor	4d3	1	MLT-0.125		To notepad
R7-R9	resistor

Sometimes it happens that the battery in the car sits down and it is no longer possible to start it, because the starter does not have enough voltage and, accordingly, current to turn the engine shaft. In this case, you can “light it up” 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 who wants 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 closer look at a homemade device, as well as instructions on how to make a charger for a car battery with your own hands.

Homemade device

Normal voltage on a battery disconnected from the vehicle is between 12.5V and 15V. Therefore, the charger must provide the same voltage. The charge current should be approximately 0.1 of the capacity, it may 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 amps, depending on the particular battery. Our homemade battery charger must meet these parameters. To assemble a charger for a car battery, we need the following items:

Transformer. We can use any of the old electrical appliances or those bought on the market with an overall power of about 150 watts, more, but not less, otherwise it will get very hot and may fail. Well, if the voltage of its output windings is 12.5-15 V, and the current is about 5-10 amperes. You can see these parameters in the documentation for your part. If there is no required secondary winding, then it will be necessary to rewind the transformer to a different output voltage. For this:

Thus, we have found or assembled the perfect transformer to make a DIY battery charger.

We will also need:

Having prepared all the materials, you can proceed to the very process of assembling a car memory.

Assembly technology

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

1. We create a homemade charging scheme for the battery. In our case, it will look like this:
   
2. We use the 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 get the desired voltage and current at the output.
   
   
3. With the help of 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. Conclusions 10 and 10 'we connect to the diode bridge.
6. Install a jumper between pins 1 and 1'.
   
7. Using a soldering iron, we attach a power cord with a plug to terminals 2 and 2 '.
8. We connect a 0.5 A fuse to the primary circuit, a 10-amp fuse, respectively, to the secondary circuit.
9. In the gap between the diode bridge and the battery, we connect an ammeter and a piece of nichrome wire. We fix one end of which, and the second should provide a movable contact, thus the resistance will change and the current supplied to the battery will be limited.
10. We isolate all connections with heat shrink or electrical tape and place the device in the case. 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 and increasing the length of the wire, you need to set the desired current value for your battery (0.1 of its capacity).
12. In the process of charging, the current supplied to the battery will decrease by itself and when it reaches 1 ampere, we can say that the battery is charged. It is also desirable to directly control the voltage on the battery, but for this it must be disconnected from the charger, since when charging it will be slightly higher than the actual values.

The first start of the assembled circuit of any power source or memory is always carried out through an incandescent lamp, if it lights up at full incandescence - either there is an error somewhere, or the primary winding is closed! An incandescent lamp is installed in the break of the phase or neutral wire that feeds the primary winding.

This scheme of a home-made battery charger has one big drawback - it does not know how to independently disconnect the battery from charging after reaching the desired 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 good example of a finished product

Operating rules

The disadvantage of a homemade 12V battery charger is that after the battery is fully charged automatic shutdown device does not occur. 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 it is strictly forbidden to check the memory “for a spark”.

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

In Soviet-made TVs, 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 wiring diagram and differ only in the type of pulse transformer and the voltage rating of the capacitor C27 at the output of the rectifier filter (see circuit diagram).

Functional diagram and principle of operation of the switching power supply of the ZUSST TV

Rice. one. Functional diagram switching power supply of the ZUSCT TV:

1 - network rectifier; 2 - start pulse shaper; 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 the 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 terminals 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 time of the open state of the pulse generator transistor. The secondary winding (terminals 6, 12) of the pulse transformer is wound and connected in such a way that during the accumulation of magnetic energy, a negative potential is applied to the anode of the VD diode and it is closed. After some time, the control stage 4 closes the transistor of the pulse generator. Since the current in the winding of the transformer 7 cannot change instantly due to the accumulated magnetic energy, an EMF of self-induction of the opposite sign occurs. Diode VD opens, and the current of the secondary winding (terminals 6, 12) increases sharply. Thus, if in the initial period of time the magnetic field was associated with the current that flowed through the winding 1, 19, now it is created by the current of the winding 6, 12. When all the energy accumulated during the closed state of the key 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, it is possible to control the amount of energy that enters the load. Such adjustment is carried out using the control stage 4 according to the feedback signal - the voltage at the terminals of the winding 7, 13 of the pulse transformer. The feedback signal at the terminals of this winding is proportional to the voltage at the load 9.

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

The moment of the next opening of the transistor 3 is determined by the stabilization device, which analyzes the signal coming from the windings 13, 7, 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 power supply network. Control stage 4 determines the range of pulses generated 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 stage ceases to function. When the stabilization stage is not working, the pulse generator turns out to be uncontrollable, which can lead to the occurrence of large current pulses in it and to the failure of the pulse generator transistor.

Schematic diagram of the switching power supply of the ZUSST TV

Consider the schematic diagram of the MP-3-3 power supply module and the principle of its operation.

Rice. 2 circuit diagram switching power supply unit for ZUSCT TV, MP-3-3 module

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 T1 pulse transformer of the 3ust power supply and VD12 diode rectifiers - VD15 with voltage regulator (VT5 - VT7).

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

The discharge current of the capacitor C7 opens the 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 the collector current of the transistor VT4 through the magnetization winding 19, 1 is accompanied by the accumulation of energy in the magnetic field of the core. After the end of the discharge of the capacitor C7, the transistor VT4 closes. The cessation of the collector current causes the appearance of an EMF of self-induction in the coils of the transformer T1, which creates positive voltages at terminals 6, 8, 10, 5 and 7 of the transformer T1. In this case, current flows through the diodes of one-half-wave rectifiers in the secondary circuits (VD12 - VD15).

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

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

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

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

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

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

At a mains voltage of 220 Volts, when the output voltages of the secondary power sources reach the nominal values, the voltage on the winding of the transformer T1 (terminals 7, 13) increases to a value at which the constant voltage at the base of the transistor VT1, where it enters through the divider Rl - R3, becomes more negative than at the emitter, where it is completely transmitted. Transistor VT1 opens in the circuit: terminal 7 of the transformer, R13, VD2, VD1, emitter and collector junctions of the transistor VT1, R6, control electrode of the thyristor VS1, R14, R16, terminal 13 of the transformer. This current, summing up 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 rise of the collector current.

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

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

When the mains voltage decreases, the voltage on the winding of the transformer T1 and the potential of the base of the transistor VT1 with respect to the emitter become correspondingly smaller. Now, due to a decrease in the voltage created by the collector current of the transistor VT1 on the resistor R10, the thyristor VS1 opens at a later time and the amount of energy transferred to the secondary circuits increases. An important role in the protection of the transistor VT4 is played by the cascade on the transistor VT2. When the mains voltage drops below 150 V, the voltage on the winding of the transformer T1 with terminals 7, 13 is insufficient to open the transistor VT1. In this case, the stabilization and protection device does not work, the VT4 transistor becomes uncontrollable and it creates the possibility of its failure due to exceeding the maximum permissible values ​​​​of voltage, temperature, current of the transistor. To prevent the failure of the transistor VT4, it is necessary to block the operation of the blocking generator. The transistor VT2 intended for this purpose is switched on 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 applied to the emitter, the amplitude of which is stabilized by the zener diode VD3. When the mains voltage decreases, the voltage at the base of the transistor VT2 decreases. Since the voltage at the emitter is stabilized, a decrease in the voltage at the base leads to the opening of the transistor. Through the open transistor VT2, trapezoidal pulses from the VD7 diode arrive at the control electrode of the thyristor, opening it for a time determined by the duration of the trapezoidal pulse. This leads to the termination of the blocking generator.

The 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 starter assembled on the VT3 transistor, and turned off using the VS1 thyristor according to the maximum collector current of the VT4 transistor. After the end of the trigger pulse, the device is not excited, since all the energy is consumed in a short-circuited circuit.

After removing the short circuit, the module enters stabilization mode.

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

The rectifier on the VD12 diode creates a voltage of 130 V to power the horizontal scanning circuit. The smoothing of the ripples of this voltage is produced by an electrolytic capacitor C27. Resistor R22 eliminates the possibility of a significant increase in voltage at the rectifier output when the load is disconnected.

A 28 V voltage rectifier is assembled on the VD13 diode, designed to power personnel scan TV. Voltage filtering is provided by capacitor C28 and inductor L2.

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

The voltage of 12 V used in the color module (MC), the radio channel module (RTO) and the vertical scanning module (MK) is created by a rectifier on the VD14 diode and capacitor C29. At the output of this rectifier, a compensating 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 the 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 fed 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 the resistor R23, voltage is supplied to the base of the transistor VT7, which is necessary to open it when turned on and recover after a short circuit. Inductor L3 and capacitor C32 - an additional filter at the output of the stabilizer.

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

Surge protector of the power supply ZUSTST

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

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

The purpose of the barrier filter is .

On the power filter board there are elements of the surge filter (C1, C2, NW, inductor L1) (see schematic diagram).

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