Switching power supply based on ne555 chip. Detailed description, application and circuit diagrams for switching on the NE555 timer. For the "Small-sized simple 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 an absolutely reliable power supply 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 unit began to produce high voltage at the output; In production, a short circuit in a line of measuring instruments almost certainly leads to a stoppage of work 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 a compensatory series stabilizer (Fig. 1). Very powerful charger circuit...

For the scheme "IMPROVEMENT OF THE POWER SUPPLY"

Power supply UPGRADES Commercially available units nutrition made in China for several voltages, when connected to a player or receiver, they give a large background of alternating current, since in the filter after the diode bridge there is only a 470 µF electrolytic capacitor. 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. The improved scheme 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 "Switching power supply" circuit

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 quickly run out 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 blocks nutrition for radio devices, including players with 3-volt power supply. The block described below provides an output voltage of 3 V at a load current of up to 400 mA, which is completely sufficient for nutrition any player or radio. For this block nutrition use a transformer and a housing from block nutrition 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 circuit "Power supply for an imported push-button telephone with Soviet logic (A"

In the vastness of the CIS, push-button telephones with Caller ID logic based on the 155 series of microcircuits also “live.” This “wild” combination of a low-current imported circuit with powerful (in terms of watts!) logic also requires appropriate power supply, especially since the “native” power supply easily burns out! ...

For the "Small-sized simple power supply" circuit

For the diagram "Repairing the power supply of a microwave oven"

About a year ago I had to repair a Bork microwave oven model MB IIEI 2623 S1, which had failed due to a significant overvoltage in the electrical network. The malfunction was completely ordinary - the management transformer failed. Replace - half an hour, at most - an hour of work. But the main problem was that the transformer I needed to repair it was not available for sale. I had to slightly redo the diagram. The work was made easier by the fact that the transformer had a diagram of its windings indicating the value of their alternating voltage. True, their output current was not specified. Figure 1 shows this transformer with power rectifiers. It completely retains the factory numbering of parts. As can be seen from the diagram, it is very simple and does not contain voltage stabilizers. Drozdov transceiver circuits Apparently, the load voltage of the upper rectifier according to the circuit is approximately 5 V, and the lower one is about 20...22 V. Judging by the diameter of the secondary windings of the transformer wires, the output current of the five-volt rectifier is unlikely to exceed 0.5... 0.6 A, and the second - 0.1 A. In the course of further work, all these assumptions were completely confirmed. The circuit of the new block nutrition shown in Fig. 2. It is based on the rather “ancient” frame scanning output transformer TVK-110-LM, which is still widely used by many radio amateurs in their work. Pin 5 of this transformer is not used. Due to the different number of windings compared to the burnt one, it was necessary to change diagram rectifiers and introduce a voltage stabilizer...

For the circuit "STARTING PULSE POWER SUPPLIES"

Power supply STARTING PULSE SOURCES Switching power supplies operating in a non-self-oscillating mode have certain advantages over self-oscillating ones: - more stringent load characteristics; - possibility of managing discrete digital signals: - improved maintainability. Launching such sources nutrition carried out by a master oscillator (MG), usually in a microcircuit design. For the MG itself to operate, it is necessary to provide its initial power supply from some external source. Sometimes, for these purposes, mains power is used with a series-connected separating capacitor, then a rectifier, a smoothing capacitor and a zener diode (Fig. 1). Fig. 1 However, with significant power consumed by the master oscillator, this option is unacceptable, since the circuit seems to “freeze” , increasing the voltage drop across capacitor C1 and not reaching the voltage nutrition ZG, determined by zener diode VD5. Power regulator on ts122 25 Increasing capacity C1 is not effective. Powering the mains generator from an additional network transformer reduces the advantages of the circuit design pulse source. For the initial start-up, we suggest using a transformerless one with a storage capacitor and a diode-thyristor optocoupler (Fig. 2). In this version, compared to the diagram in Fig. 1, there is no “freezing” of the circuit with significant current consumption of the DC. The storage capacitor is capacitance C2. It is charged through C1 and the rectifier VD1...VD4 to a value determined by the...

For the scheme "UMZCH FOR PLAYER"

AUDIO equipmentUMZCH FOR PLAYER Sometimes you want to listen to music in the yard with friends. But it’s inconvenient to carry a large tape recorder, and the player is designed for one. I suggest a simple diagram amplifier with an output power of approximately 3 W (Fig. 1). The main advantage of the circuit is low voltage nutrition(same as the player - 3...6 V). This diagram can be used in a minicassette recorder to increase its power. Any speakers can be used, but with a power of at least 3 W and a resistance of 4 ohms. Instead of KA2206, you can use the TA8227R IC. The pinout of the microcircuit is shown in Fig. 2. N. KHATSKEVICH, Belov, Kemerovo region...

How to connect a rheostat to a charger If the voltage drop across resistor R2 becomes greater than that across resistor R3, the voltage at the output of the DA2 chip will decrease, diode VD4 will open and the output voltage will decrease to a value corresponding to the set current limit. The transition to current stabilization mode is indicated by the HL1 LED turning on. Since in short-circuit mode the op-amp output voltage must be less than -1.25 V by approximately 2.4 V (voltage drop across diode VD4 and LED HL1), the negative source voltage nutrition The op amp was chosen to be -6 V. This role is needed for all positions of switch SA2, so we had to switch the rectifier input VD2, VD3....

When choosing a power source to power LEDs, the right solution would be a PWM voltage regulator - for example, on the NE555 chip. The principle of operation of such a device is to pulse the supply of a given constant voltage to an LED with different duty cycles. So, for example, if a voltage pulse lasting only 0.1 second is applied to an LED per unit of time (for example, one second), then the brightness of the LED will be 10% of its power, and if a pulse lasting 0.9 seconds is applied - 90%. This process is shown in graph 1.

The PWM circuit of the LED brightness controller is shown in Figure 1. The circuit is assembled on the NE555 chip and is a pulse generator with an adjustable duty cycle. The duty cycle of the pulses of this device depends on the rate of charge and discharge of capacitor C1. The charge of capacitor C1 is carried out through the circuit R2, D1, R1, C1, and the discharge is carried out by C1, R1, D2, pin 7 of the microcircuit. Thus, by changing the resistance of resistor R1, we change the charging and discharging time of capacitor C1 - thereby adjusting the duty cycle of the pulses at the output of the microcircuit (pin 3). At pin 3 of the microcircuit, the logical value “0” is +0.25V, and the logical value “1” is +1.7V. Thus, a voltage of +0.25V will not open transistor T1 - and at the output of the device, during a given period of time, there will be no voltage, and a voltage of +1.7V will open transistor T1 completely. Transistor T1 is represented by a CMOS field-effect transistor IRFZ44N whose power reaches 150 W. However, if you use more powerful transistors as T1, you can achieve greater output power of the device. As diodes D1, D2, you can use diodes 1N4148 or any of the series diodes 1N4002 - 1N4007.

Fig.1. Circuit PWM LED brightness controller on NE555

This device is also widely used as a speed controller for DC motors. To do this, another diode is added to the circuit, installed at the output of the device (the cathode of the diode is connected to +Upit., the anode of the diode is connected to the drain of transistor T1. This diode protects the device from reverse voltage coming from the motor after turning off the power to the device.

I needed to make a speed controller for the propeller. To blow away the smoke from the soldering iron and ventilate the face. Well, for fun, pack everything into a minimum price. The easiest way to regulate a low-power DC motor, of course, is with a variable resistor, but to find a motor for such a small nominal value, and even the required power, it requires a lot of effort, and it will obviously not cost ten rubles. Therefore, our choice is PWM + MOSFET.

I took the key IRF630. Why this one MOSFET? Yes, I just got about ten of them from somewhere. So I use it, so I can install something smaller and low-power. Because the current here is unlikely to be more than an ampere, but IRF630 capable of pulling through itself under 9A. But it will be possible to make a whole cascade of fans by connecting them to one fan - enough power :)

Now it's time to think about what we will do PWM. The thought immediately suggests itself - a microcontroller. Take some Tiny12 and do it on it. I threw this thought aside instantly.

1. I feel bad about spending such a valuable and expensive part on some kind of fan. I'll find a more interesting task for the microcontroller
2. Writing more software for this is doubly frustrating.
3. The supply voltage there is 12 volts, lowering it to power the MK to 5 volts is generally lazy
4. IRF630 will not open from 5 volts, so you would also have to install a transistor here so that it supplies a high potential to the field gate. Fuck it.

What remains is the analog circuit. Well, that’s not bad either. It doesn’t require any adjustment, we’re not making a high-precision device. The details are also minimal. You just need to figure out what to do.

Op amps can be discarded outright. The fact is that for general-purpose op-amps, already after 8-10 kHz, as a rule, output voltage limit it begins to collapse sharply, and we need to jerk the fieldman. Moreover, at a supersonic frequency, so as not to squeak.

Op-amps without such a drawback cost so much that with this money you can buy a dozen of the coolest microcontrollers. Into the furnace!

What remains are comparators; they do not have the ability of an op-amp to smoothly change the output voltage; they can only compare two voltages and close the output transistor based on the results of the comparison, but they do it quickly and without blocking the characteristics. I rummaged through the bottom of the barrel and couldn’t find any comparators. Ambush! More precisely it was LM339, but it was in a large case, and religion does not allow me to solder a microcircuit for more than 8 legs for such a simple task. It was also a shame to drag myself to the storehouse. What to do?

And then I remembered such a wonderful thing as analog timer - NE555. It is a kind of generator where you can set the frequency, as well as the pulse and pause duration, using a combination of resistors and a capacitor. How much different crap has been done on this timer over its more than thirty-year history... Until now, this microcircuit, despite its venerable age, is printed in millions of copies and is available in almost every warehouse for a price of a few rubles. For example, in our country it costs about 5 rubles. I rummaged through the bottom of the barrel and found a couple of pieces. ABOUT! Let's stir things up right now.

How it works
If you don’t delve deeply into the structure of the 555 timer, it’s not difficult. Roughly speaking, the timer monitors the voltage on capacitor C1, which it removes from the output THR(THRESHOLD - threshold). As soon as it reaches the maximum (the capacitor is charged), the internal transistor opens. Which closes the output DIS(DISCHARGE - discharge) to ground. At the same time, at the exit OUT a logical zero appears. The capacitor begins to discharge through DIS and when the voltage on it becomes zero (full discharge), the system will switch to the opposite state - at output 1, the transistor is closed. The capacitor begins to charge again and everything repeats again.
The charge of capacitor C1 follows the path: “ R4->upper shoulder R1 ->D2", and the discharge along the way: D1 -> lower shoulder R1 -> DIS. When we turn the variable resistor R1, we change the ratio of the resistances of the upper and lower arms. Which, accordingly, changes the ratio of the pulse length to the pause.
The frequency is set mainly by capacitor C1 and also depends slightly on the value of resistance R1.
Resistor R3 ensures that the output is pulled to a high level - so there is an open-collector output. Which is not able to independently set a high level.

You can install any diodes, the conductors are approximately the same value, deviations within one order of magnitude do not particularly affect the quality of work. At 4.7 nanofarads set in C1, for example, the frequency drops to 18 kHz, but it is almost inaudible, apparently my hearing is no longer perfect :(

I dug into the bins, which itself calculates the operating parameters of the NE555 timer and assembled a circuit from there, for astable mode with a fill factor of less than 50%, and screwed in a variable resistor instead of R1 and R2, with which I changed the duty cycle of the output signal. You just need to pay attention to the fact that the DIS output (DISCHARGE) is via the internal timer key connected to ground, so it could not be connected directly to the potentiometer, because when twisting the regulator to its extreme position, this pin would land on Vcc. And when the transistor opens, there will be a natural short circuit and the timer with a beautiful zilch will emit magic smoke, on which, as you know, all electronics work. As soon as the smoke leaves the chip, it stops working. That's it. Therefore, we take and add another resistor for one kilo-ohm. It won’t make a difference in regulation, but it will protect against burnout.

No sooner said than done. I etched the board and soldered the components:

Everything is simple from below.
Here I am attaching a signet, in the native Sprint Layout -

And this is the voltage on the engine. A small transition process is visible. You need to put the conduit in parallel at half a microfarad and it will smooth it out.

As you can see, the frequency floats - this is understandable, because in our case the operating frequency depends on the resistors and capacitor, and since they change, the frequency floats away, but this does not matter. Throughout the entire control range, it never enters the audible range. And the entire structure cost 35 rubles, not counting the body. So - Profit!

Adjusting the speed of electric motors in modern electronic technology is achieved not by changing the supply voltage, as was done before, but by supplying current pulses of different durations to the electric motor. PWM, which has recently become very popular, is used for these purposes ( pulse width modulated) regulators. The circuit is universal - it also controls the engine speed, the brightness of the lamps, and the current in the charger.

PWM regulator circuit

The above diagram works great, attached.

Without altering the circuit, the voltage can be raised to 16 volts. Place the transistor depending on the load power.

Can be assembled PWM regulator and according to this electrical circuit, with a conventional bipolar transistor:

And if necessary, instead of the composite transistor KT827, install a field-effect IRFZ44N, with resistor R1 - 47k. The polevik without a radiator does not heat up at a load of up to 7 amperes.

PWM controller operation

The timer on the NE555 chip monitors the voltage on capacitor C1, which is removed from the THR pin. As soon as it reaches the maximum, the internal transistor opens. Which shorts the DIS pin to ground. In this case, a logical zero appears at the OUT output. The capacitor begins to discharge through DIS and when the voltage on it becomes zero, the system will switch to the opposite state - at output 1, the transistor is closed. The capacitor begins to charge again and everything repeats again.

The charge of capacitor C1 follows the path: “R2->upper arm R1 ->D2”, and the discharge along the path: D1 -> lower arm R1 -> DIS. When we rotate the variable resistor R1, we change the ratio of the resistances of the upper and lower arms. Which, accordingly, changes the ratio of the pulse length to the pause. The frequency is set mainly by capacitor C1 and also depends slightly on the value of resistance R1. By changing the charge/discharge resistance ratio, we change the duty cycle. Resistor R3 ensures that the output is pulled to a high level - so there is an open-collector output. Which is not able to independently set a high level.

You can use any diodes, capacitors of approximately the same value as in the diagram. Deviations within one order of magnitude do not significantly affect the operation of the device. At 4.7 nanofarads set in C1, for example, the frequency drops to 18 kHz, but it is almost inaudible.

If after assembling the circuit the key control transistor gets hot, then most likely it does not open completely. That is, there is a large voltage drop across the transistor (it is partially open) and current flows through it. As a result, a lot of power is dissipated for heating. It is advisable to parallel the circuit at the output with large capacitors, otherwise it will sing and be poorly regulated. To avoid whistling, select C1, the whistling often comes from it. In general, the scope of application is very wide; its use as a brightness regulator for high-power LED lamps, LED strips and spotlights will be especially promising, but more on that next time. This article was written with the support of ear, ur5rnp, stalker68.

The 555 timer chip (domestic analogue of KR1006VI1) is so universal that it can be found in the most unexpected electronic components. This article discusses switching power supply circuits that use this microcircuit.
In a home laboratory, especially in the field, a low-power source of different constant voltages is needed, which can be powered from batteries or galvanic cells, lightweight and portable. Similar circuits of switching power supplies, which are commonly called DC/DC converters, can be created using a 555 timer. It so happens that we use the NE555 microcircuit in our designs, but any of its analogues can be used in the circuits under consideration.

Bipolar voltage switching power supply circuit

It is assembled on a single NE555 chip (Fig. 1), which serves as a master generator of rectangular pulses. The generator is assembled according to the classical scheme. The generator output pulse repetition rate is 6.474…6.37 kHz. It varies depending on the supply voltage, which can be 3.6 V (3 batteries in a power cassette) and 4.8 V (with 4 batteries in a power cassette). In the switching power supply circuit, ENERGIZER AA batteries with a capacity of 2500 mAh were used.
Rectangular pulses from output 3 of MS 555 are fed through limiting resistor R5 to the base of transistor switch VT1, the load of which is inductor L1 with an inductance of 3 mH. When this transistor is abruptly closed, a large self-induction EMF is induced in inductor L1. The high-voltage pulses obtained in this way are supplied to two parallel rectifiers with voltage doubling, the outputs of which will have two opposite-polar voltages ±4.5...15 V.

These voltages can be adjusted by changing the duty cycle of the output pulses using potentiometer R1. The constant voltage from the R1 engine reaches pin 5 of the MC555 and changes the duty cycle, and therefore the output voltage of both rectifiers. The output voltages of this source will be ideally equal only when the duty cycle of the generator pulses is equal to 2 (the duration of the pulses is equal to the pause between them). With a different duty cycle of the pulses, the output voltages of the source at points A and B will differ slightly (up to 1...2 V). Such a small difference is ensured by the use of doubling rectifiers in the switching power supply circuit, the capacitors of which are charged by both positive and negative pulses. This disadvantage is compensated by the simplicity and low cost of the scheme.

In this switching power supply circuit, you can use chokes from electronic ballasts of unusable energy-efficient fluorescent lamps. When disassembling these lamps, be careful not to damage the spiral or U-shaped glass tubes, as they contain mercury. It is better to do this outdoors.
On some chokes, especially imported ones, the inductance value in mH is marked (2.8, 2.2, 3.0, 3.6, etc.).
Input and output voltages, current consumption and pulse repetition rates for the circuit in Fig. 1 are given in Table 1.

Switching power supply circuit for two NE555

Figure 2 shows a switching power supply circuit with two NE555 timers. The first of these microcircuits (DD1) is connected according to a multivibrator circuit, the output of which appears short rectangular pulses taken from pin 3. The repetition rate of these pulses is changed using potentiometer R3.
These pulses are sent to the differentiating circuit C3R5 and the diode VD1 connected in parallel to resistor R5. Since the cathode of the diode is connected to the power bus, short positive bursts of differentiated pulses (edges) are shunted by the small forward resistance of the diode and have an insignificant value, and negative bursts (falls), falling on the locked diode VD1, freely pass to the input of the waiting multivibrator MS DD2 (leg 2 ) and launch it. Although VD1 is indicated in the diagram as D9I, in this position it is advisable to use a low-power Schottky diode, and, in extreme cases, you can use a silicon diode KD 522.

Resistor R6 and capacitor C6 determine the duration of the output pulse of the standby multivibrator (one-shot) DD2, which controls switch VT1.
As in the previous circuit of a switching power supply, the current through transistor VT1 is regulated by resistor R7, and the load is a choke made from the ballast of economical 3 mH fluorescent lamps.
Since the MS generation frequency is lower than in the first circuit, the voltage doubling rectifier capacitor C7 has a capacity of 10 μF, and to reduce the size, a ceramic SMD capacitor is used in this position, but other types of capacitors can be used: K73, KBGI, MBGCh, MBM or electrolytic at a suitable voltage.
Input and output voltages, current consumption and pulse repetition rates for the circuit in Fig. 2 are given in Table 2.

Switching power supply circuit based on NE555 timer and operational amplifier

The switching power supply circuit shown in Fig. 3 is similar, but an operational amplifier (OA) type K140 UD12 or KR140 UD 1208 is used as the master oscillator of rectangular pulses. This op amp is very economical, can operate from a unipolar supply voltage from 3 to 30 V or from bipolar ±1.5... 15 V.
The generation frequency is adjusted with potentiometer R3. To increase broadband, pins 1,4,5 are combined and grounded to a common wire. Resistor R6, which regulates current control, is reduced to the minimum possible value of 100 kOhm. The current consumption of the op-amp is within 1.5…2 mA. Between the output of the op-amp and the differentiating circuit C3R10VD1, from which the one-shot DD1 is launched, a buffer amplifier is connected on a transistor VT1 of type BC237, which serves to increase the steepness of the front and fall of the output pulse MS DA1.


The load of the VT2 switch uses inductor L1 from the same ballasts from energy-efficient lamps. This inductor is protected from overvoltage by the R13VD2 chain. Its inductance is 1.65 mH, but it is wound with a thicker wire, therefore, its active resistance is lower and its quality factor is higher. This allows you to get a voltage of approximately 24...25 V at the output of the rectifier with doubling VD3VD4.
It should also be noted that the switching power supply circuit in Fig. 3 can operate from a unipolar supply voltage of 3.3 V.
Input and output voltages, current consumption and pulse repetition rates for the circuit in Fig. 3 are given in Table 3.