Scheme of the power supply circuit s 120 12. Switching power supply: repair and modification

Power supply IMPROVEMENT OF POWER Commercially available Chinese-made power supplies for several voltages when connected to a player or receiver give a high background alternating current, since in the filter after the diode bridge there is only an electrolytic capacitor of 470 μF. I propose a simple modification to the block, which significantly reduces the level of pulsation. Additional parts are placed in the body of the block itself. advanced does not require any special explanation. It is advisable to install the transistor on a small radiator made of a piece of tin. Voltage switch SB1, after modifying the circuit, gives levels “shifted” by 1.5V. If desired, you can resolder the conductors suitable for SB1 and recreate the correspondence between those indicated on the switch and the output voltages, but then there will be no upper limit (12 V). O. KLEVTSOV, 320129, Dnepropetrovsk, Sholokhov street, 19 - 242. (RL-7/96)...

For the circuit "MOVEFUL FREQUENCY ADJUSTMENT GENERATOR FOR P134"

Amateur radio equipment components SMOOTH FREQUENCY ADJUSTMENT GENERATOR FOR P134 Discrete frequency setting in 1 kHz steps in the P134 radio station makes it difficult to use for amateur radio purposes. It is quite simple to obtain the probability of smooth frequency tuning up to ±4 kHz relative to the tuning frequency on the digital scale of the radio station. To do this, it is enough to change the signal with a frequency of 10 MHz supplied from the radio frequency synthesizer (block 2-1) through the multiplier block 3-3 per mixer block 3-1, by a signal of a quartz oscillator with a frequency of 10 MHz tunable up to ±500 Hz according to the circuit shown in Fig. 1.Puc.1 Since in a mixer block 3-1 the eighth harmonic of the generator is used, the operating frequency of the radio station will vary within ±4 kHz, which is completely sufficient. Resistor R7 in the circuit is selected within 0.5...2 kOhm, depending on the activity of the quartz used, until the nominal signal level is obtained at the output of the radio station when the key is pressed in AT-T mode. Zu for horse racing circuit Coil L is made on a ring magnetic circuit of brand 50VCh2 of standard size K7x4x2 with PELSHO wire 0.1 mm and contains 15 turns. Using a well-calibrated receiver, it is advisable to select the number of coil turns with an accuracy of one to obtain a generator frequency of 10 MHz ± 50 Hz in the middle position of the R4 regulator, while the operating frequency of the radio station will correspond to the frequency on the digital scale. Quartz resonator It is advisable to use it in a vacuum version. The generator can be powered with a voltage of +12.6 V from capacitors C2...C6 of the decoupling filter in the power circuit block 2, which can be accessed by removing the top block N9 radio station. The printed circuit board of the device is shown in Fig. 2, the location of the parts on it is shown in Fig. 3. The board is conveniently placed in a shielded cassette unit with dimensions of 140x70x30 mm, mounted on the radio body to the left of the operator. On the face...

For the diagram "Power supply for the player"

Nowadays, many people have players from various companies. All of them are powered by finger-type batteries. These batteries have a small capacity and run out quickly when using the player. Therefore, in stationary conditions, it is better to power players from the mains via a power supply, since the price of batteries these days is “biting”. In the radio engineering literature there are descriptions of various power supplies for radio devices, including for players with 3-volt power supply. The block described below provides output voltage 3 V at a load current of up to 400 mA, which is completely sufficient to power any player or radio. For this block power supply uses a transformer and a housing from block power supply for a microcalculator type MK-62 (“Electronics D2-10m”). The primary (network) winding is left at the transformer, and the secondary winding is rewound. Now it contains 270 turns of PEL or PEV 0.23 wire. ...

For the "Eternal Power Supply" circuit

To operate a TV, computer, or radio, a stabilized power supply is required. Devices connected to the network around the clock, as well as circuits assembled by a novice radio amateur, require absolutely reliable power supply (BP) so that there is no damage to the circuit or fire of the power supply. And now a few “horror” stories: one of my friends, when a control transistor broke down, lost many microcircuits in a homemade computer; in another, after shorting the wires going to an imported radiotelephone with a chair leg, the power supply melted; the third has the same thing with the power supply of a “Soviet” industrial TA with caller ID; for a novice radio amateur, after a short circuit, the power supply began to deliver high voltage to the output; at the production line KZ measuring instruments almost certainly leads to a stoppage of operation and the need for urgent repairs. We will not touch upon the circuits of pulse blocks due to their complexity and low reliability, but will consider the circuit of a compensatory serial power regulator (Fig. 1). ...

For the circuit "Laboratory power supply 0...20 V"

Power supply Laboratory block supply 0...20 V Under this heading in "Radio", 1998, #5 a description of a simple block power supply on KR142 series microcircuits. Feature of the new version block is the probability of smoothly setting the threshold for limiting the output current from units of milliamps to the maximum value. The main difference between the modified nutrition (Fig. 1) is contained in the introduction operational amplifier DA2 and installing a negative voltage stabilizer microcircuit -6 V instead of -1.25 V. As long as the output current is small and the voltage drop across the current-measuring resistor R2 is less than that installed by resistor R3, at the output of 6 op-amps and at the input of the DA1 microcircuit (pin 2) the voltage values ​​are approximately equal, the diode VD4 is closed and the op-amp does not participate in the operation of the device. If the voltage drop across resistor R2 becomes greater than across resistor R3, the voltage at the output of microcircuit DA2 will decrease, diode VD4 will open and the output voltage will decrease to the value corresponding to the set current limit. Horse racing circuit diagram The transition to current stabilization mode is indicated by turning on the HL1 LED. Because in mode short circuit The output voltage of the op amp should be less than -1.25 V by approximately 2.4 V (voltage drop across the diode VD4 and the LED HL1), the voltage of the negative power supply of the op amp is selected equal to -6 V. This role is necessary for all positions of the switch SA2, so we also had to switch the input of the rectifier VD2, VD3. The KR1168EN6B microcircuit can be replaced with a similar one with index A, with MC79L06 with indices BP, CP and ACP, as well as with KR1162EN6...

For the scheme "Digital scale + frequency meter DS018 (radio dial)"

Digital technology Digital scale/Frequency meter DS018 Device characteristics: Measured frequency range 1 kHz...35 MHz. Frequency reading resolution 100 Hz. Reading update rate constant, 5 times/sec. Input signal voltage not less than 0.5 V. eff.Device supply voltage: 7...24V.Consumption current no more than 100mA** Total current consumption of DS018 and DLED1_6 no more than 70mA.Measuring Features Blok DS018 Possibility of use in frequency meter mode. Separate version of the Measuring block DS018 and Indicator. Minimum number of connecting wires (GND; Data). Reading update rate 5 times/sec. Data transfer rate from Measuring Blok DS018 to the Indicator was chosen as minimal as possible, which made it possible to get rid of interference on the sensitive receiving path of the transceiver without any additional shielding. Separate power supply of the Measuring Blok DS018 and Indicator. The length of the communication line between the Measuring unit and the indicator is up to 5 meters (I). Digital hysteresis of the least significant digit minimizes its “jitter”. Possibility of parallel connection of an unlimited number of indicators to one DS018 Measuring Unit (duplication of readings). Operable in transceivers using local oscillator frequency doubling (*2). Supports up to 12 operating ranges. Short-term transition to frequency meter mode when pressing a button located on the Measuring Unit board. Possibility of repeated (at least 100,000 times) reprogramming by the User of the IF value or the “stand” frequency for each range separately as well as the sign (addition or subtraction ).Easy to understand and convenient for the User to change settings.Non-volatile EEPROM memory for storing User settings.Safety of User settings for more than 10 years without supply voltage.User-disabled EEPROM memory armor from accidental erasure during power failures.Possibility of electronic cal...

For the scheme "EXPANDING THE FREQUENCY RANGE OF THE UHF STB"

TelevisionEXPANSION OF THE FREQUENCY RANGE UHF STANDBONESUntil recently, many types of UHF set-top box selectors were produced, designed to receive television signals on any of the 21 UHF channels (from 21 to 41) and convert them into meter range signals (1st and 2 th channel). Absence block UHF in televisions of previous generations forced many to purchase UHF set-top boxes. In Vitebsk, a transmitter on channel 48 was recently turned on. To expand the received range to the 59th channel, I propose the simplest modification of the Uman selector set-top box and similar ones with a range of 21 ... 41 channels. The improvement consists of increasing the tuning voltage (UH) of the vari-caps to 26 V (instead of 18 V). To do this, you need to break the connection between stabilization resistors R2 and R3 and apply pin 3 of resistor R2 to point R1 (Fig. 1). You can do this by switching through a toggle switch (Fig. 2) - then the range of 21...41 channels is preserved. Puc.2After this, tune to the 48th channel (or another of this order) as usual. This modification is done in a similar way on other types of UHF selector set-top boxes, designed to receive 21...41 channels. Their schemes are practically unified. V. REZKOV, 210032, Vitebsk, Chkalova st., 30/1 - 58. ...

For the "Small-sized simple power supply" circuit

The power supply described below can be used for portable and small-sized radio devices (radios, radios, tape recorders, etc.). Technical data: Output voltage - 6 or 9 V Maximum load current - 250 mA The power supply has a parametric current stabilizer and a compensation voltage stabilizer. Therefore, it is not afraid of a short circuit at the output, and the output transistor of the stabilizer practically cannot fail. Scheme block power supply is shown in the figure. The parametric current stabilizer includes the R1C1 chain and the primary winding of the T1 transformer. The compensation voltage stabilizer is assembled on elements R2, VT1, VD2, VD3, VD4. The operation of the circuits has been repeatedly described in the literature and is not presented here. LED VD5 (red) with ballast resistor R3 serves to indicate operability block nutrition. Details: C1 - any small-sized paper with a rating of 0.25 µF x 680 V; C2, SZ - 1000 µF x 16 V; VD1 - KTs407A; VD2 - D18; VD3 - KS139A; VD4 - KS156A; VD5 - AL307A, B; VT1 - KT805AM; T1 - magnetic circuit Ш12 x 18, primary winding 2300 turns with PEV-0.1 wire, secondary - 155 turns with PEV-0.35 wire. The power supply fits into a plug housing from an imported adapter. O.G. Rashitov, Kiev...

For the "Switching power supply" circuit

I propose a simple scheme switching power supply. It differs from previously published diagrams in its simplicity, minimal number of parts and does not contain scarce elements. A correctly assembled unit does not require adjustment or configuration. The unit is also not afraid of short circuits and load breakage at the output. The disadvantages include small output power- 1 W load and high output ripple. Scheme block presented in the figure. As you can see from the diagram, this is a regular blocking generator. During forward motion, energy accumulates in the core of the transformer "And, during reverse motion, the output voltage is applied to the open diode VD3 and accumulates on capacitor C4 and then goes to the load. Unlike conventional circuits, the blocking generator is powered by a pulsating half-wave voltage. In view small capacitance C1, and also thanks to the current-limiting resistors R1 and R2, the voltage on the capacitor does not exceed 120 V in operating mode. Intercom electronics pu-02 In this case, it turned out to be possible to use a relatively low-voltage transistor in the unit. The purpose of the elements VD4, VD5 is to limit the reverse voltage on the collector junction of transistor VT1, at a safe level.In addition, the chain VD4, VD5 stabilizes the output voltage within 16 V without load, i.e. serves as a load for block in the absence of external load. Therefore, the presence of this chain is mandatory. The T1 transformer is made on the B-22 M2000NN armored core. Winding Ia contains 150 turns, winding Ib contains 120 turns. The windings are made with PELSHO wire 0 0.1 mm. Winding II contains 40 turns of PEL wire 0 0.27 mm, winding III contains 11 turns of PELSHO wire 0 0.1 mm. First, winding Ia is wound, followed by winding II. After this winding 16 and finally winding III. Instead of transistor VT1 could...

For the diagram "HOW TO INCREASE THE SERVICE LIFE OF A CINESCOPE"

TelevisionHOW TO INCREASE THE SERVICE LIFE OF A CINESCOPE Assembling a circuit for delaying the switching on of a picture tube according to the article by A. Ilyin (RL 4-95), option for block MZZ, I found that this device needs some improvements. 1. Zener diode VD1 in the circuit is used as a key element that opens with voltage, and its operating current here is much less than 3 mA - the minimum permissible according to technical conditions. In this mode, the opening threshold of the KS 156 zener diode turned out to be only approximately 2 V (at a current of 30 μA). Therefore, to increase the delay time and more efficient use of capacitance C1, it is better to install a second zener diode VD1.1 in series with VD1. Also, to increase their operating current, it is advisable to reduce R3 to 30 kOhm. 2. With a capacitance of C1 of 220 μF, the device is ready to be turned on again no earlier than after 30 s, since the discharge occurs through R4 with high resistance. Do-it-yourself charger for a miner's flashlight To speed up this process, R4 should be bypassed with a diode VD2. When charging, it is closed by the voltage from the +12 V source, and after turning off the TV, it opens with potential from C1, and the discharge quickly occurs through the direct resistance of the diode. 3. Instead of C1 at 6.3 V, it is better to take a 25 V capacitor. Capacitors at a higher voltage are more stable, and most importantly, they “dry out” less over time. All of the above applies to the option for MC2, because they have the same delay interval generation unit. A. SKORLUPKIN, 410028, Saratov, Radishcheva St. 23 "b" - 2. (RL 3/98)...

Have you ever wanted to turn on the TV, stereo or other equipment when you are in the car or relaxing in nature? An inverter should solve this problem. It converts 12 V DC to 120 V AC. Depending on the power of the Q1 and Q2 transistors used, as well as how “big” transformer T1 is, the inverter can have an output power from 1 W to 1000 W.

Schematic diagram

List of elements

Notes

1. Transistors Q1 and Q2, as well as transformer T1, determine the output power of the inverter. With Q1, Q2 = 2N3055 and T1=15A, the inverter has an output power of 300 Watts. To increase power, the transistors and transformer must be replaced with more powerful ones.
2. The easiest and cheapest way to get a large transformer is to rewind a transformer from a microwave oven. These transformers have an output power of up to 1000 watts and good quality. Go to a repair shop or look at a junkyard and pick out the largest microwave. The larger the oven, the larger the transformer. Remove the transformer. Do this carefully, do not touch the terminal of the high voltage capacitor, which may still be charged. You can check the transformer, but they are usually fine. Careful not to damage the primary winding, remove the secondary (2000V) winding. Leave the primary one in place. Now wind 24 turns of enameled wire over the primary winding with a tap from the middle of the winding. The diameter of the wire will depend on the current you require. Insulate the winding with electrical tape. The transformer is ready. Choose more powerful transistors Q1 and Q2. The listed 2N3055 parts are rated at only 15A.
3. Remember that when eating powerful load, the circuit consumes huge current. Don't let your battery die.
4. Since the output voltage of the converter is 120V, it must be placed in a housing.
5. Only tantalum capacitors must be used as C1 and C2. Conventional electrolytic capacitors overheat and explode due to constant overcharging. The capacitor capacity can only be 68 µF - no change.
6. There may be some difficulties in running this scheme. If there is an error in the installation of the circuit, the design of the transformer, or if the components are incorrectly replaced, the converter may not work.
7. If you want to get a voltage of 220/240 V at the output of the converter, you need to use a transformer with a primary winding of 220/240 V (according to the circuit, it is secondary). The rest of the circuit remains unchanged. The current that the inverter will draw from a 12 V source at an output voltage of 240 V will be twice as much as at a voltage of 120 V.

In the past about power supplies, I mentioned that I ordered two units for review, today I will talk about the second test subject.
In its own way it is interesting and well made, but not without its shortcomings.
All more detailed information, as always, is under the cut.

I already had a power supply with the same power and the same voltage, but in this case these power supplies are radically different, which prompted me to take it for the test.
The review will be in the same format as always, but the comments and conclusions will be completely different.

I’ll start today in an unusual way, with packaging :)))
The power supply, like last time, had its own cardboard “house”. But this time there was a marking on the package - Led power supply, although it has nothing to do with powering the LEDs specifically since it works as a source of voltage, not current, but in this case of great importance it doesn't have.
There is also a power marking on the side, and I immediately noticed that at first it was highlighted - 150 Watts, then crossed out and marked - 180 Watts, but we will return to this later.

The first distinguishing feature of this power supply is its form factor. The power supply is made on the basis of a U-shaped aluminum chassis that acts as a radiator; usually power supplies are made in the form of an L-shaped chassis with a perforated casing.
This design should improve cooling of power elements and reduce the size of the block, but the heating test will come later.

The dimensions of the power supply are very modest, length 200mm, width 59mm, height 36mm.

At the ends of the block there are connectors for connecting 220 Volt power + grounding and 12 Volt output.
The output terminals are made double, with two contacts for each polarity.
This is caused by a rather large output current, up to 15 Amps; in this option it is more convenient to connect the load.

Each terminal block has a protective cover. In a previous review of the 180 Watt power supply, I was asked if the lid opened all the way, as a person had problems with it.
The lid, although it has rather tight latches, opens at 90 degrees.

The manufacturer claims the following characteristics:
Input voltage - 110/220 Volts ± 15% (which is strange since the power supply does not have a voltage switch)
Output voltage - 12 Volts
Output current - 15 Amperes.

Since there was nothing else interesting outside, I climbed inside.
The unit is extremely easy to disassemble; there are four screws on the sides, unscrewing which you can easily remove the top cover.
The first thing that caught my eye was that the power supply was assembled using single-cycle circuitry.
In my personal opinion, a power supply with a power of 180 Watts assembled according to this scheme is already on the border of good and evil.
The fact is that at low powers such a circuit works perfectly, but at high powers push-pull, bridge or half-bridge ones already “rule the roost” (this circuitry is used in most computer power supplies).
This BP is located approximately on the border of the division of “spheres of influence”.

The power supply survived the first power-up quite normally, which in itself is pleasant :)
Initially it was set to 12.21 Volts (only later did I understand why).
The adjustment range is not very large, minimum 11.75, maximum 12.63.
After checking the adjustment range, I set the power supply to the stated 12 Volts.

Several photos of the main components of the power supply.
1. Surge filter, this time there is a thermistor that protects against current surge when the power supply is turned on, there is a place for a protective varistor, but they “forgot” to solder it.
2. The input capacitor has a capacity of 150 μF, looks more like a proprietary one, and is designed for a maximum temperature of 105 degrees. If it weren’t for the reduced capacity, then I would say that it’s excellent, but otherwise it’s just good.
3. High voltage transistor pressed using an L-shaped plate. there is a paste, and it looks like silicone.
4. Two diode assemblies are installed at the output, also pressed with a metal plate through the paste, but to the other wall of the housing.

Let's look further. The board is screwed onto one mounting screw, inserted into the slots of the housing itself, and can only be inserted and removed together with a dielectric insert.
You can see that the board is almost empty; only large elements are installed on top of it.
This is how branded power supplies are usually made (at least that’s what I remember).

Printed circuit board.

A couple of more detailed photos of the printed circuit board.
Secondary side, precision resistors are used, this is good, the circuit layout is also interesting feedback, it’s clear that they still thought about the tracing. By the way, the power supply is made by the same manufacturer as the previous one for 24 Volts.

Primary side.

An unknown to me was used as a PWM controller.
But I noticed that the manufacturer placed a ceramic capacitor parallel to the electrolyte in the power circuit of this microcircuit. This happens quite rarely, but in vain.
The current measuring shunt is made in the form of six resistors connected in parallel.

The circuit diagram is slightly different from the previous power supply.
In the diagram, some positions have a designation of the form - 22 (11) and a serial number of the element consisting of several numbers. This means that several parallel elements are installed; the total value is given in brackets.

Selected photographs of the main components of the power supply.
1. Input power filter elements, noise suppression capacitor and inductor.
2. Thermistor to limit starting current and diode bridge, this time the diode bridge is 4 Ampere 600 Volt.
3. Additional noise suppression capacitors, correct Y type.
4. High voltage transistor. The transistor is in an insulated housing, designed for current up to 12 Amperes and voltage up to 650 Volts. In my opinion, it could have been installed more powerfully, but the test showed that everything was in order with it.

1. The interwinding capacitor is also of the correct Y type, which is rare these days.
Next to it there is an empty space for installing the same capacitor, connecting the minus of the output circuit to the power supply housing, but it was also “forgotten”. I won’t say that it is very important, but it would not be superfluous.
2. Output diode assemblies, no questions, the parameters correspond to the output current and voltage of the power supply.
A few words about the transformer. Made correctly, it is clear that the primary winding is made of two wires and is divided into two parts (this is desirable to improve the connection between the windings). The output winding is made of four wires, although at such currents a Litz winding looks better.

The output capacitors are made up of five pieces. Before the choke, three pieces of 1000 μF for 25 Volts are installed, after which there are two pieces of 1000 μF for 16 Volts. I think it was worth installing all capacitors at 25 Volts at least. And ideally, before the choke, 35 Volts, after - 25 Volts, but this is rarely found even in branded power supplies.
The output choke has been detuned; the location allows you to install a choke with a higher inductance and designed for a higher current. I would recommend replacing it with a more suitable one.
A small measurement of the capacitance of the capacitors showed that the indicated and actual capacitance corresponded.

Well, actually, we’re done with the review of the design and elemental base, now we can safely move on to testing.
For this purpose, the same “stand” was assembled as in the previous review. It included:
Experimental power supply.
Electronic load
Oscilloscope
Multimeter
Non-contact thermometer

The testing methodology is almost standard.
Switch on, load, warm up for 20 minutes, increase load current, warm up for 20 minutes, etc. until we hit the maximum current, or until the power supply makes its last squeak.
The oscilloscope probe divider was in the 1:1 position, the oscilloscope division price was set to 0.1 Volt.
1. First check at idle, output voltage is 11.98 Volts.
2. Increasing the load current to 3 Amperes, the voltage dropped sharply to 11.65 Volts.

After I saw that the output voltage dropped sharply under a relatively light load, I immediately remembered that it was originally set to 12.21 Volts.
Apparently the load resistors located at the output of the block do not quite cope with their function and the output voltage rises at idle.
I had to adjust the output voltage to 11.99 Volts at a current of 3 Amps.
I didn't touch the regulator anymore.

1. Load current 6 Amperes, voltage 12 Volts, ripples occur with a voltage of about 0.4 Volts
2. Load current 9 Amperes, voltage 11.92 Volts, the range of ripples has hardly changed, but they have become more frequent.

1. Load current 12 Amperes, voltage 11.84 Volts, ripple voltage about 0.5 Volts
2. The load current is about 14 amperes (the load no longer provides), the voltage dropped to 11.8 Volts, but the ripples have already increased quite significantly and amounted to 0.65 Volts.

As I wrote above, data on the temperature of the components was taken every 20 minutes.
The first value is idling after about 20-30 seconds of running at a current of 10 Amps (this happened), the next ones were removed before the next increase in current.
The last value is an additional 20-minute warm-up to assess the dynamics of temperature growth. The total test time was 2 hours.
Temperatures measured:
High voltage transistor, transformer, output diodes, output capacitors.
The temperature of the output diode was taken to be the value with higher temperature(one assembly had a temperature several degrees higher).


At almost maximum current load, the power supply noticeably overheats, so during operation you should not count on a current of more than 12 Amps.

At the end of the experiment, I took a picture of the heating of the entire power supply as a whole; unfortunately, I don’t have a thermal imager yet, so that’s the only way.

Summary.
pros
Nice and well thought out design.
Having a power filter with the correct types of capacitors.
Most of the components are selected correctly and according to the power of the power supply.

Minuses
High ripple level can be improved by replacing the output choke.
Large heating at maximum current, unfortunately, cannot be corrected by simple modifications.

My opinion. At the very beginning, I wrote that I would return to talk about the power of the power supply, which was originally indicated on the packaging. I believe that the initially indicated 150 Watt is the power at which this power supply can operate quite safely.
I was pleased with the good design, the presence of a full-fledged power filter, and the correct capacitors (affects safety). But I was upset heat, and if it is familiar for semiconductors, then it is dangerous for the transformer and output capacitors.
The capacitor capacity, in my opinion, is somewhat underestimated and is also more suitable for a power of 150 watts rather than 180.
The total result is a completely normal, well-made power supply with a power of 144 Watts, or, in other words, 12 Volts 12 Amps.

I hope that the review was useful and will allow you to make the right choice.

The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.